S.K.P. Engineering College, Tiruvannamalai

Transcription

1 SKP Engineering College Tiruvannamalai A Course Material on By Mr.N.Karunagaran, Mr.G.Delhibabu, Mr.N.Sarankumar,Mr.E.Karthikeyan Assistant Professor 1

2 Quality Certificate This is to Certify that the Electronic Study Material Subject Code: ME 6702 Subject Name: Year/Sem: IV / VII Being prepared by Mr.N.Karunagaran, Mr.G.Delhibabu, Mr.N.Sarankumar, Mr.E.Karthikeyan and it meets the knowledge requirement of the University curriculum. Signature of the Author Name: Mr.N.Karunagaran Mr.G.Delhibabu Mr.N.Sarankumar Mr. E.Karthikeyan Designation: Assistant Professor This is to certify that the course material being prepared by Mr.N.Karunagaran, Mr.G.Delhibabu, Mr.N.Sarankumar, Mr.E.Karthikeyan is of the adequate quality. He has referred more than five books and one among them is from abroad author. Signature of HD Signature of the Principal Name: Dr.J.Kuberan Name: Dr.V.Subramania Bharathi 2

3 ME6702 MECHATRONICS LTPC 3003 OBJECTIVES: To impart knowledge about the elements and techniques involved in systems which are very much essential to understand the emerging field of automation. UNIT I INTRODUCTION 12 Introduction to Systems Concepts of approach Need for Emerging areas of Classification of. Sensors and Transducers: Static and dynamic Characteristics of Sensor, Potentiometers LVDT Capacitance sensors Strain gauges Eddy current sensor Hall effect sensor Temperature sensors Light sensors UNIT II 8085 MICROPROCESSOR AND 8051 MICROCONTROLLER 10 Introduction Architecture of 8085 Pin Configuration Addressing Modes Instruction set, Timing diagram of 8085 Concepts of 8051 microcontroller Block diagram.. UNIT III PROGRAMMABLE PERIPHERAL INTERFACE 8 Introduction Architecture of 8255, Keyboard interfacing, LED display interfacing, ADC and DAC interface, Temperature Control Stepper Motor Control Traffic Control interface. UNIT IV PROGRAMMABLE LOGIC CONTROLLER 7 Introduction Basic structure Input and output processing Programming Mnemonics Timers, counters and internal relays Data handling Selection of PLC. UNIT V ACTUATORS AND MECHATRONIC SYSTEM DESIGN 8 Types of Stepper and Servo motors Construction Working Principle Advantages and Disadvantages. Design process-stages of design process Traditional and design concepts Case studies of systems Pick and place Robot Engine Management system Automatic car park barrier TOTAL : 45 PERIODS TEXT BOOKS: 1. Bolton,, Printice Hall, Ramesh S Gaonkar, Microprocessor Architecture, Programming, and Applications with the 8085, 5th Edition, Prentice Hall, REFERENCES: 3

4 1. Michael B.Histand and Davis G.Alciatore, Introduction to and Measurement systems, McGraw Hill International edition, Bradley D.A, Dawson D, Buru N.C and Loader A.J,, Chapman and Hall, Smaili.A and Mrad.F, Integrated Technologies for Intelligent Machines, Oxford University Press, Devadas Shetty and Richard A. Kolk, Systems Design, PWS publishing company, Krishna Kant, Microprocessors & Microcontrollers, Prentice Hall of India, Clarence W, de Silva, "" CRC Press, First Indian Re-print,

5 CONTENTS S.No Particulars Page 1 Unit I 6 2 Unit II 45 3 Unit III 68 4 Unit IV 93 5 Unit V 111 5

6 Unit I Part A 1.Define mechatronics and sketch the graphical representation of mechatronics system? [Odd-2004, Even-2006] is the synergistic integration of mechanics and mechanical engineering, electronics, computer technology and IT to produce are enhancing products and systems. 2. What are the elements in typical mechatronics system? *Actuators and sensors *signal and conditioning *Digital logic systems *Software and data acquisition system 6

7 *Computer and display devices. 3. What are the types of mechatronics systems? *Class 1: primarily mechanical product with electronics incorporated to enhance functionality. *Class 2: Traditional mechanical systems with significantly updated internal devices incorporation electronics. The external user interfaces are unaltered. *Class 3: System that retains the functionality of the traditional mechanical system, but the internal mechanism are replaced by electronics. *Class 4: Products designed with mechanical and electronic technologies through synergistic integration. 4. What are the main applications of mechatronics? *NC and CNC machine tools, rapid prototyping robots *Computer disc drives and VCR/DVD drives *Automatic washing machines, dish washer, rice cooker and automatic ovens. *Automatic teller machine (ATM) *Automatic/digital camera, digital watch. 5. What are the advantages and disadvantages of mechatronics system? Advantage: *Cost effective and good quality product *High degree of flexibility to modify or redesign *Very good performance characteristics 7

8 *Wide area of applications *Greater productivity in case manufacture organization *Greater extend of machine utilization. Disadvantage: *High initial cost *Multi disciplinary engineering background required to design *Need of high trained workers *Complexity in identification and correction of problems in the system 6. What is mean by system in mechatronics? The word system in mechatronics refer to group of physical component connected or related in such a manner as to form a entire unit for performing specific tasks, a system can be treated as block box having input and output as shown in fig. 7. What is mean by measurement system in mechatronics? A measurement system involves the precise measurement and display/recording of physical, chemical, mechanical, electrical or optical parameters. It provides a mean of describing natural phenomena in quantitative terms. 8. What are the basic elements of measurement system and sketch its block diagram? A generalized measurement system comprises of sensors /transducer, signal processor and a display/recording device as shown in figure below. Sensor transducer Signal processor Display recording device 8

9 9. What is mean by control system in mechatronics? A control system in mechatronics refer to a group of physical component connected or related in such a manner as to command direct or regulate itself or another system. The physical components may be of electrical, mechanical, hydraulic, pneumatic, thermal or chemical in nature. 10. Give some applications of control systems? *Idle speed control system of an automobile *Print wheel control system of a printer *Temperature control of an electric furnace or oven. *Sun tracking control of solar collector. *Aircraft rudder control system. *Gun or missile director. *Missile guidance system *Laser-guidance projectiles. 11. How the control systems are classified? Control system are classified into two groups *Open loop control system *Closed loop or feedback control systems. 12. What are basic functions of control systems? 9

10 *To minimize the error b/w the actual and desired O/P. *To minimize the time response to load charges in the systems. 13. What is meant by open loop system? Give examples. Open loop systems are system in which the output of a system is not used as a variable to control the system. In other words, open loop systems are system in which I/P to the system is not controlled by the present O/P. Examples: Electric fire alarm system bread toaster, chemical addition pump. 14. What are the elements of open loop system? The basic elements of this system are an amplifier and a controller as shown in figure. The amplifier receives a low- level input signal and amplifier it enough to drive the controller to perform the desired job. Amplifier Controller 15. What are the advantages and disadvantages of open loop control system? Advantage: *Simple and cost effective construction *Easy maintenance because of no complex electronic circuits *Good stability *Good reliability *Quicker response *No calibration problem Disadvantage: 10

11 *Less accurate *Presence of non-linearity causes malfunctioning *Slow because of manual control *Optimization in control not possible 16. What is meant by closed loop control system? Give examples. Closed loop system uses on a feedback loop to control the operation of the system in closed loop or feedback control the controller notices what actually take place at the output end and drives the plant in such a way as to obtain the desired output. Examples: Automatic tank level control system, Automatic temperature control system, Automatic positioning system for a miscible launcher, Automatic shaft speed control system. 17. What are the advantages and disadvantages of close loop control system? Advantage *Closed loop control, with appropriate sensor provides much greater stability *Closed loop control will also give much better repeatability. *Closed loop control overcomes temperature and hysteresis effects. *Closed loop control can perform a task faster than open-loop *Good reliability. *Optimization in control is possible. Disadvantage: *Generally closed loop control systems are complicated in construction. 11

12 *Cost of system is higher. *sometimes closed control loop system may become uncomfortable. 18. Draw the basic feedback system and indicate the various terms associated with this block diagram? [Even-2006] The basic elements of closed loop system are shown in the figure *Reference input * Plant or process *Controlled variable *Comparison element *Error signal *Controller *correction element *Measuring element. 19. Distinguish between open loop and closed loop control systems. (Odd-2007) Open loop: *Open loop operation does not use on a feedback to control the operation of the system. 12

13 *Effects of known disturbances alone can be controlled. *Less accurate. *Simple in construction. *Presence of non-linearity s can cause malfunctioning. *Slow response because of manual control. *Optimization in control not possible. Closed loop: *Closed loop operation using negative feedback. *The effects of disturbances are countered by the virtue of negative feedback. *More accurate *complicated in constructions *Closed loop control can perform a task faster than open-loop. *Optimization in control is possible. 20. What is meant by sequential control systems? Give examples. A sequential control involves sequential execution of well defined operations that are performed in prescribed order. EXAMPLES: Automatic washing machine system, Automatic teller machine, CNC machines. 21. How the microcontrollers differ from the microprocessor? Microprocessors and microcontroller are similar, but the architecture of both differs in the application domains.microprocessors is employed for high speed applications such as desktop and laptop computers. Whereas the microcontrollers are 13

14 employed in automation and control application, such as microwave ovens, automatic washing machines, dish washers, engine management systems, etc. 22. What are the elements of microprocessor based controller or micro controllers? A microcontroller generally has the main CPU core, ROM/EPROM/RAM and some accessory functions (like timers, pulse with modulator, AID convertor and I/O controllers) all integrated into one chip. Microcontroller is a computer on a chip that is programmed to perform almost any control, sequencing, monitoring and display functions. 23. Sketch the basic structure of a PLC. 24. Identify the different mechatronics systems used in automobiles. [Even-2008] 14

15 Automobile application of mechatronics include electronic engine management system, collision detection system, global positioning system, antilock brake system, keyless entry system, cruise control, parking assistance system and many more. 25. How do you define the sensors? Sensors are devices which produce a proportional output signal (mechanical, electrical, magnetic, etc) when exposed to a physical phenomenon (pressure, temperature, displacement, force etc.). 26. What is transducer? How the transducers differ from sensor? Transducer is a device which convert an input of one form of energy in to an output of another form of energy he term transducer is often used synonymously with sensors. However ideally, the word `transducer is used for the sensing element itself whereas the term sensor is used for the sensing elements plus any associated signal conditioning circuitry. 27. How do you classify the sensors? Based on its power requirement sensor are generally classified into two ways: Passive sensor and Active sensors Based on the type of output signal sensors can also be classified as Analog sensor and Digital sensors Based on the relationship between input and output sensors are generally classified into 2 type 15

16 Primary sensor Secondary sensors. Based on quality to be measured sensors are classified as: Displacement sensors Proximity sensors Force, torque and pressure sensors Velocity and acceleration sensors Flow sensors Level sensors Temperature sensor and Light sensors. 28. State the difference between primary and secondary transducers. [Odd-2003] Primary sensor produces the output which is the direct measure of the input phenomenon. Secondary sensors on the other hand produced output which is the direct representation of the physical phenomenon. Mostly active sensors are referred as primary sensors, where as the passive sensors are referred to as secondary sensors. 29. What do you understand by term static and dynamic characteristics of transducers? Static characteristic of an instrument are the parameters which are more or less constant or varying very slowly with time. Dynamic characteristics of an instrument are the parameters which are varying with time. 30. Define error? 16

17 Error is the difference between a measured value and the true input value. ERROR=Measured value-true input value. 31. Distinguish between accuracy and sensitivity of the transducer. [Even-2006] ACCURACY: *Accuracy may be defined as the ability of an instrument to respond to a true value of a measured variable under the reference conditions. *It refers to how closely the measured value agrees with the true value. *It is the relationship indicating how much variation a measured value has with the true value. *It has no unit. *Accuracy of an instrument is depending on the components and observer. *The accuracy of the instrument should be as high as possible. SENSITIVITY: *Sensitivity of an instrument is defined as the ratio of the magnitude of the output signal to the magnitude of the input signal. *It denotes the smallest change in the measured variable to which the instrument responds. *It is the relationship indicating how much output may be obtained per unit input. *Some of the inputs of sensitivity are millimeter per micro-ampere, millimeter per ohm, counts per volt, ohms per degree Celsius etc. 17

18 *Sensitivity of an instrument is only depending on the components. 32. A quartz piezoelectric crystal having a thickness of 2mm and a voltage sensitivity 0.005vm/N subjected to a pressure of 1.38*10^6N/m^2.calculate the voltage output. [Odd-2004] Given data: Thickness=2mm=0.002m Voltage sensitivity, vs =0.055vm/N Pressure=1.38*10^6N/m^2 Solution: Output voltage =vs.*t*p =0.055*0.002*1.68*10^6 =151.8v 33. A thermometer is calibrated from 200degre celecius to 300 deg c, the accuracy is specified within +or 0.25% what is the maximum static error? SOLUTION: Span of thermometer= =100 deg.c Maximum static error=+ or_0.25*100/100 =+ or -0.25deg.c 34. What is hysteresis? Hysteresis is defined as the maximum differences in the output for a given input when the value is approached from the opposite direction. It is a phenomenon which shows different output when loading and unloading. 18

19 35. Define the terms Repeatability and reproductability. Repeatability may be defined as the ability of the sensor to give same output reading when the same input value is applied repeatedly under same operating conditions. Reproducibility may be defined as the degree of closeness among the repeated measurements of the output for the same value of input under the same operating condition at different times. 36. What is meant by steady state and transient state? An output whose magnitude has a definite repeating time cycle is called steady state periodic. An output whose magnitude does not repeat with time is known as transient. 37. State the dynamic characteristics of simplified measuring system. [Apr-04] *Response time. *Time constant *Rise time *setting time. 38. What are displacement sensors? Give various displacement sensors commonly used in mechatronics systems. Displacement sensors are those sensors which measures the variation of position of a body. Displacement sensors are designed to give quantitative measurement of the displacement being measured, the various displacement sensors commonly used in the mechatronics systems are: (a)potentiometer displacement sensors (b)strain gauge displacement sensors (c)capacitive displacement sensors 19

20 (d)inductive displacement sensors (LVDT). 39. State the purpose using potentiometer in displacement sensors. Potentiometer is a primary sensor which converts the linear motion or the angular motion of a shaft into changes in resistance. 40. What are the factors to be considered while selecting the potentiometer? *Operating temperature *Shock and vibration *Humidity *Contamination and seals 41. List the advantages and disadvantages of potentiometers. Advantage: *Easy to use *Low cost *High-amplitude output signal *Proven technology *Rugged construction *Very high electrical efficiency *Availability in different forms ranges and sizes. Disadvantage: *Limited bandwidth *Frictional loading 20

21 *Inertial loading *Limited life due to wear. 42. How the strain gauge is used to measure displacement? The strain gauge displacement sensor consists of a structure attached with a strain gauge that elastically deforms when subjected to a displacement. This causes an increase in resistivity of the gauge which provides the electrical signal proportional to the deformation. 43. How the output of the strain gauge is measured? The change of resistance of strain gauge is very small and is usually measured using a Wheatstone bridge circuit where the strain gauge is connected into the circuit with a combination of four active gauges for full bridge two gauges for half bridge or a single gauge or quarter bridge. 44. Define gauge factor. what will be the change resistance of an electrical resistance strain gauge with a gauge factor of 2.1 and resistance 50ohm its subject to a strain of 0.001[Even-2006] Gauge factor is the ratio of change of the resistance per unit resistance to the strain changes of the resistance /unit resistances Delta R/R=G*E Change of the resistance, delta R=G*E*R =2.1*0.001*50 =0.105ohm. 45. How the gauges are classified based on its construction? Bonded foil types-they consist of a pattern of resistive foil which is mounted on a backing material. 21

22 Wire wound gauges are made of round wire of copper nickel, chrome nickel or nickel iron alloys, about in diameter. 46. Illustrate the different form of capacitive sensor based on the principle of operation (a)illustrate the distance variation of parallel plates for displacement sensing (b)illustrate the transverse displacement principle where the transverse displacement is easily detected by overlap or under lap area of the parallel plates. The dielectric object is kept between the plates as shown in figure. (c)as the dielectric object moves between the plates, the capacitance changes linearly with motion. 47. What are the applications, advantages and disadvantages of capacitive displacement sensor? APPLICATION: This sensor can be employed for measuring position, displacement, and gauging or any other similar parameter in a machine tool. Advantage: *Excellent linearity over entire dynamic range, when area is changed. 22

23 *High sensitivity *The system responds to average displacement of a large of a moving electrode. *capacitors are noiseless *High accuracy and resolution. Disadvantage: *The performance of this sensor is likely affected due to the environmental conditions, such as dust, moisture, vibration etc. *The metallic parts of the capacitor must be insulated from each other. 48. Write short notes on LVDT LVDT is a variable-inductance displacement transducer. It is an electro mechanical device designed to produce an AC voltage output proportional to the relative displacement of the transformer and the ferromagnetic core.lvdt consist of a removable core of magnetic material and three coils comprising static transformer. One of the three coils is pick-up coils. When AC current is passed through the primary coil, an AC voltage is induced in the secondary coils. The magnetic core inside the coil winding assembly provides the magnetic flux path linking the primary and secondary coils. When the magnetic core is displaced from the null position, a certain number of coil winding are affected by the proximity of the sliding core and thus an electromagnetic imbalance occurs. This imbalance generates a differential AC output voltage across the secondary coil which is linearly proportional to the direction and magnitude of the displacement. 49. What is meant by RVDT? Rotational variable differential transfer is used to measure rotational angles and operates under the same principles as the LVDT sensor. Whereas the LVDT uses a cylindrical iron core, the RVDT uses rotary ferromagnetic core. 23

24 50. What are the applications, advantages and disadvantages of LVDT? APPLICATIONS: LVDT can be used to measure the displacement, deflection, position and profile of work piece. Advantage: *Relative low cost due to its popularity. *Solid and robust, capable of working in a wide variety of environments. *High signal to noise ratio and low output impedance. *High sensitivity up to 40V/mm. Disadvantage: *The performance of these sensors is likely affected by vibration etc. *Relatively large outputs are required for the appreciable output. *Not suitable for fast dynamic measurement. *Internally low in power output. 24

25 UNIT-I PART-B 1. Describe the building blocks of a mechatronics system indicating various Modules involved in it. [Odd-2004] Various elements in typical mechatronics system are shown in figure. And are described here under *actuators and sensors *signals and conditioning *digital logic system *software and data acquisition system *computers and display devices 1) Sensors and actuators: Sensors and actuators mostly come under mechanical system.the actuators produce motion or cause some action. The sensor detects the state of the system parameters, inputs and outputs. The various Actuators used in mechatronics system are pneumatic and hydraulic actuators, electromechanical actuators, electric motors such as D.C motors, A.C motors, stepper motors, servo motor and piezo electric actuators. The various type of sensor used in mechatronics system are linear and rotational sensors. Acceleration sensors, force, torque and pressure sensors, proximity sensors, light sensors. 25

26 2) Signals and conditioning: The mechatronics system and with two types of signal and conditioning, input and output. the input devices receives the input signal from the mechatronics system via interfacing devices and sensors and then sent to control system for conditioning and processing.the various input signal conditioning devices used in mechatronics System are discrete system, amplifiers, analog-to digital converter (A/D),digital to digital (D/D) converter. The output from the system are sent to the output/ display devices through inter facing devices.the various output signal condition devices used in mechatronics system are digital to analog (D/A) converters, display decoders (DD) converters, amplifiers, power transistors, power op-amps. 3) Digital logic system: Digital logic system control overall system operation. The various digital logic system used in mechatronics system are logic circuits, micrometers, programmed logic controllers, sequencing and timing controls, control algorithms. 4) Software data acquisition system: Data acquisition system acquires the output signal from sensors in the form of voltage, frequency, resistance etc. and inputting into the microprocessor computer software is used to control the acquisition of data through DAC board. The data acquisition system control amplifier registers and control circuitry DAC board. The various data acquisition system used in mechatronics system is data loggers, computer with plug in boards etc. 5) Computer and display devices: Computers are used to store large number of data and process further through software. Display devices are used to give visual feedback to the user.the various display devices used in mechatronics system are LEDs, CST, LCD, digital display etc. 2.Explain the open and closed loop control system with neat sketch. [Even-2005] 26

27 OPEN LOOP SYSTEMS: Open loop system in which the output of a system is not used as a variable to control the system, in other word, open loop system are system in which input to the system is not controlled by the present output. In a open loop system the output of this system is not feed back into the input to the system for control or operation. An open system is essentially a feedback system the system is an open system because it does not have a feedback loop in its control as shown in figure. There are many reasons to use loop control such as simplifying the control, the quicker response of the system to reduce the possibility. Of oscillations and sometimes lower cost. System CLOSED LOOP CONTROL SYSTEM: Closed loop system used as a feedback loop to control the operation of the system. In closed loop or feedback control the controller notices what actually takes place at the output and drives to the plant in such a way as to obtain the described output. Closed-loop control system are the type most commonly used, because they respond and move the loads they are controlling quicker and with greater accuracy is that on automatic feedback system informs the input that the direct movement has taken place. 3.What are the basic elements of closed loop system? [Odd-2007] In this system the actual output is fed back and compared with the desired response, the resulting error is the basic for the application of a control signal to the plant the controller generate the control signal on the basis of the error. If a mechanical has to be applied to the plant it is generated by an actuator from the output of the controller. In this arrangement the control signal takes the actual controlled variable into account including disturbance if any the plant is driven until the error is reduced. This is the principle of feedback control in which the control is negative. 27

28 From the above description it is cleared that s closed loop control system must be capable of following. (1)Accepting an order that defines the desired result. (2)Determine the present condition by some method of feedback. (3)Comparing the desired result with the present conditions and obtaining a difference or an error signal. (4)Issuing a correcting order that will properly change the existing conditions to the desired result. (5)Obeying the correcting order. 4.Identify the various elements of closed loop system in automatic water level controller and describe their functions. [Odd-2007] 28

29 In this system, the various elements are: Plant or processor: The water storage tank Controller variable: The storage tank level Manipulated variable: The flow rate of water supplied to the tank Reference input: The desired tank level Comparison elements: the level controller Error signal: The difference between the current and required water level Controller: The level controller Correction element: The level control valve Measuring element: The level transducer. 5.Explain the function of closed loop system with a neat sketch for controlling speed of shaft. [Even-2006] 29

30 Figure shows the schematic of an automatic shaft speed control system. The potentiometer is used to set the voltage to be supplied to the differential amplifier. The differential amplifier is used to compare elements which amplifies the feedback signal and compares the feedback value and reference value The amplifier error signal is fed to dc motor to adjust the speed of the rotating shaft. The digital tachometer is used as transduction to measure the speed of the rotating shaft and is feed back to the amplifier. Figure illustrated the working signal flow of this system in block diagram. 6. Explain sequential control system. [Even-2005] In many situations, various operations of plant or process take place in particular order. A sequential control involves sequential execution of well defined operation that is performed in a prescribed order. Each activity or operation is called step. Each step may be open or closed loop continuous process or a even a sequential sub-process for examples while using automatic camera that various basic steps in sequence are switch on /off,taking the image, saving the image and then switching off the camera. 30

31 Each step of the prescribed sequence usually requires a switching of equipment configuration and may be triggered by time or an event. The sequential controller may be classified into 2 types *Event based and *Time based. In event based controllers, the next event or step cannot be performed until the previous step or event is completed. In time based controller, the series of operation are sequenced with respect to time even based controller are more reliable than the time based controllers. Traditional such as control could be obtained by an electrical circuit which sets of cam operate switches or relays which are wired up in such a way as to give a desired sequence now a days, microprocessor or computer controlled system are used instead of hard-wired circuits with the sequencing being controlled by software programs. Industrial sequential control may employ relay or semi conductor logic; more complicated operations are controlled by programmable logic controllers (PLCS). 7. What is sequential controller? Explain how a microprocessor based controller operates a washing machine. [Even-2006] In modern automatic washing machine,the cam operated switches are replaced with microprocessor based controller whereas are fed to perform various sequential operations.in addition to the microprocessor controller, various sensors,and drivers are used to effectively and automatically carry out these operations, the timer installed in the system determines the time for which the cycles to be activated. The various sensors such as level sensor, position sensor temperature sensor, speed sensor provide input signal to the microprocessor, The working of modern automatic washing machines is explained under with the help of block diagram shown in figure. 31

32 Pre Wash Cycle: Pre-wash cycle may involve the following sequence of operations. Opening of valve to fill the drum when a current is supplied Microprocessor is used to operate the switch for opening closing the valve. Closing the valve after receiving the signal from a sensor when the required level of water is filled in the washing drum. Stopping the flow of water after the current is switched off by the microprocessor. Switch on the motor to rotate for stipulated time. Initiates the operation of pump to empty the water from the drum. Pre-wash cycle involves washing the clothes in the d m by cold water. Main Wash Cycle: 32

33 Main wash cycle involves washing the clothes in the drum by hot water and the sequence of operations in main wash is as follows: Cold water is supplied after the Pre-wash cycle is completed. Current is supplied in large amount to switch on the heater for heating the cold water. Temperature sensor switches off the current after the water is heated to required temperature. Microprocessor or cam switch ON the motor to rotate the drum Microprocessor or cam switches on the current to a discharge pump to empty the drum. Rinse Cycle: Rinse cycle involves washing out the clothes with cold water a number of times and the sequence of operations in a Rinse cycle are as follows: Opening of valve to allow cold water into the drum when the microprocessor are given signals to supply current after the main wash cycle is completed. Switches off the supply current by the signals from microprocessor Operation of motor to rotate the drum Operation of pump to empty the drum and respect this sequence a number of times. Spinning Cycle Spinning cycle involves removing of water from the clothes and the sequence of operations Switching on the drum motor to rotate it at a higher speed than a rinsing cycle. 8. Explain the static performance characteristics of a sensor. [Even-2005, Even-2005] 1. STATIC SENSOR: Static characteristics of an instrument are the parameters which are more or less constant or varying very slowly with time. 33

34 2. RANGE: Every sensor is designed to work over a specified range i.e. maximum and minimum values. Certain 3. SPAN: It represents the highest possible input value which can be applied to the sensor without causing unacceptably large inaccuracy. SPAN=Maximum value of the input-minimum value of the input. 4. ERROR: Error is the difference between the measured value and the true input value. ERROR=Measured value-true input value. 5. ACCURACY: A very important characteristics of a sensor is accuracy which really means inaccuracy. 6. SENSITIVITY: Sensor sensitivity is defined as the change in output per change in input.the factor may be constant over the range of the sensor or it may vary. SENSITIVITY=change in output/change in input 7. HYSTERESIS: Hysteresis is defined as maximum differences in output for a given input when this value is approached from the opposite directions. 34

35 8. LINEARITY: * Linearity of a sensor refers to the output that is directly proportional to input over its entire range, so that the slope of a graph of output versus input describes a straight line. NON_LINEARITY: * Non-linearity of a sensor refers to the output that is not proportional to the input over its entire range, so that the slope a graph of output versus input describes curves. 35

36 9. REPEATABILITY: * It may be defined as the ability of the sensor to give same output reading when the same input value is applied repeated by under the same operation condition. 10. REPRODUCIBILITY: *It may be defined as the degree of closeness among the repeated measurements of the output for the same value of input under the same operating conditions at different times. 11. STABILITY: *Stability means the ability of the sensor to indicate the same output over a period of time for a constant input. 12. DEAD BAND/TIME: *Dead band of a sensor is the range of input values for which the instrument does not respond. 36

37 *Dead time is the time taken by the sensor from the application of input to begin its response and change. 13. RESOLUTION: *It is defined as the smallest change that can be detected by a sensor. 14. ZERO DRIFT: *Drift is the variation of change in output for a given input over period of time. 15. OUTPUT IMPEDANCE: *Impedance is the ratio of voltage and current flow for a sensor; two types of impedance are important in sensor application input impedance and output impedance. 9. Describe the dynamic characteristics of a sensor. [Apr-08] Sensors and actuators respond to input that change with time. Any system that changes with time is considered a dynamic system; dynamic characteristics of an instrument are parameters which are varying with time. The following characteristics are dynamic characteristics. *RESPONSE TIME: The time taken by sensor to approach its true output when subjected to a step input is sometimes referred to as its response time.it is more usual however to quote a sensor having a flat response between specified limits of frequency,this is known as frequency response and it indicates that if the sensor is subjected to sinusoidal oscillations input to constant amplitude the output will faithfully reproduce a signal proportional to the input. *TIME CONSTANT: It is the time taken by the system to reach 63.2% of its final output signal amplitude (i.e.) 62.3% of response time.a system having smaller time constant reached its final output faster than the one with larger time constant.therefore process higher speed of response. 37

38 *RISE TIME: It is the time taken by the system to reach 63.2% of its final output signal. *SETTING TIME: It is a time taken by a sensor to be within a close range of its steady state value. 10. Explain an incremental (optical) encoder what are their application? [Nov-04] Incremental rotary encodes are preferred when low cost is important or when only relative position is needed. The incremental encoder sometimes called a relative encoder, consists of two tracks and two sensors whose output are called channel A and B as the shaft rotates pulse trains occurs on these channels at a frequency proportional to the shaft speed, and the phase relationship between the signal yields the direction of rotation incremental encoder often have a third channel called index channel with a signal segment slot or reference fields one pulse per revolution which is useful in counting full revolutions.it is also useful as a reference to define a home base or zero position. The code disc pattern and output signal AB the index by counting the number of pulse and knowing the number of radial lines in the disc rotation of the shaft can be measured.the direction rotation is determined by the phase relationship of A and B pulse trains (i.e.) which signal loads the others. For example a rising edge of A and B is 1 may indicate clockwise rotation while a rising edge of A while B=0 indicate the clockwise rotation. The signals from the two channels are a 1/4 cycle phase which each other and are known as quadrature signal. 38

39 A drawback of the incremental encoder is that there is no way to know the absolute position of the shaft at power up without rotating it until the index pulse is received. Also if pulse is momentarily garble due to electrical noise the estimation of the shaft rotation is lost until the index pulse is received a solution to their problems is the absolute encoder. 11. How taco generator is used to measure angular velocity? [Even-2006] Taco generator or tachometer is used to measure the angular velocity of a rotating shaft or object. An electrochemical energy is a device capable of producing electric power from mechanical energy, usually the turning of a shaft. A generator specially designed and constructed for shaft speed measurement is called a tachometer or taco generator. Tachometer operated on the principle that a driven motor produces a voltage that is proportional to the angular velocity of the motor shaft.the proportionality constant, k that is used to translate mechanical motion into RPM. One form of taco generator is variable reluctance taco generator. It consist of a ferromagnetic footed rotor mounted on the shaft whose speed is to measured us a magnetic pick up consist of a small permanent magnet with a coil wound around it 39

40 magnetic pick up arrangement is placed near the footed rotor changes the rise in emf is induced in the pickup coil. The output is in the form of pulsed and wave shapes.by counting the number of pulse in a particular time interval the angular velocity can be calculated by using the following equation The speed of rotor, N=pulsed per minute/number of teeth in rpm. Tachogenerator can also indicate the direction of rotation by the polarity of the output voltage when a permanent magnet, style DC generator rotational direction is reversed the polarity of its output voltage will switch.in measurement and control system where directional indicates an easy way to determine that. Tachogenerator are frequently used to measure the speed of electric motors, engines and the equipments they power. Conveyor belts, machine tools, mixers, fans, etc. 12. Explain the principle and application of proximity and light sensor.[even-2005] PROXIMITY SENSOR: Proximity sensors are used to determine the presence of nearby objects.they are essentially non contact two state devices which give n-off outputs. A proximity sensor often emits electromagnetic field or beam and look for changes in field 40

41 the object being sensed is often referred to us the proximity sensors target. Different proximity sensor target demand different sensor for example, a capacitive or photoelectric sensor might be suitable for a plastic target an inductive proximity sensor requires a metal target. Such proximity sensors are classified into several type in accordance with the specific properties used to initiate a switching action. (1) Optical encoder (2) Hall effect sensor (3) Capacitive sensors (4) Eddy current proximity sensor (5) Inductive proximity sensor (6) Pneumatic proximity sensors (7) Proximity sensors The first three are already discussed under displacement and positive sensors. The other types are discussed. LIGHT SENSOR: A light sensor or detector converts the radiant power it absorbs into a change of a device parameter such as resistance, surface charge, current or voltage some signal conditioning electronics may also be needed to convert the basic output from the detector into a more useful voltage signal for example,for digitization by an analog to analog(adc)they may be integrated into the detector or required external components. there are several types of light sensors is use common use the principle of operation and characteristics of the most commonly used including photo resistor, photodiode and phototransistor are summarized in the section. These light sensors depend on the generator causes change in device resistance in the case of photo resistors or an output current or output voltage in the case of photodiode and transistor. 13. With a neat sketch explain the working of proximity pneumatic sensor. [Even2008] Pneumatic proximity sensor, as shown in figure used the principle of a gas nozzle to detect the presence of an object without any mechanical contact. Low pressure air is supplied through annular converging nozzle surrounding a sensing hole called output port.nozzle may also be of converging diverging type. If desired sensing 41

42 hole communicates through hole with switch chamber which contains an elastic diaphragm switch or other type of pressure sensitive switch. Nozzle converts some of the energy of the supply air into kinetic energy as the air steam from nozzle impinges upon an object to be sensed a turbulence and bulk pressure at output port and activates switches. 14. Explain the principle and operation s of the following with neat sketches. (a)fluid pressure sensor (b) Temperature sensor. [Even-2005] (a)fluid PRESSURE SENSOR: The differential pressure detector method of liquid level measurement uses a differential pressure cell connected to the bottom of the tank being monitored.the higher pressure caused by the fluid in the tank compared to a lower reference pressure this comparison takes place in the differential pressure cell. A typical differential pressure detector attached to an open tank. The tank is open to the atmosphere therefore it is necessary to use only the high pressure connection on the differential pressure cell. The pressure side is vented to the atmosphere.therefore the pressure differential is the hydrostatic level or weight of the liquid in tank. 42

43 TEMPERATURE SENSOR: Temperature measurement is most widely monitored parameter in science and industry.temperature is defined as the average kinetic energy of the individual molecules that comprise the system the system. As the temperature increases the molecular simple mercury thermometer is needs the fluid or process temperature.this uses the principle of expansion or Contraction of liquid, gases, or solids. There are also often technique such as change in electrical resistance of conductors and semiconductors and thermoelectric emf used to measured the temperature. The following are common method used to measure the temperature which is described in details. (1) Bimetallic strips (2) Resistance temperature detector(rtd) (3) Termites (4) Thermocouples (5) Thermo diodes and transistors 15. Describe the function of a bourdon tube pressure gauge in detail. [Odd-2003] The bourdon tube pressure instrument is one of the oldest pressure sensing instrument in use today, it is widely used in application where inexpensive 43

44 static pressure measurement are needed. The bourdon tube consist of a thin walled c-shaped tube that is flattened diametric an opposite side to produce a cross sectional area elliptical shape having two long flat sides and two short round sides. The tube is open to external pressure input on one end and is coupled mechanically to an indicating needle on the pressure applied to the inside of the tube causes distinctions of the flat section and tent to restore its original round-section. Within limits the movement of the at the tube can be used to position a pointer or to develop an equivalent electrical signal to indicate the value of the applied internal pressure. 44

45 UNIT-2 Part A 1. A pneumatic system is operated at a pressure of 1000kpa.what diameter cylinder will be required to move a load requiring a force of 12kn? Given data: Force F=12kn; Pressure=1000kpa Solution: Force= pressure X area Area =force/pressure =12/1000 =0.012m2 Area of the piston A=/4 X D2 0.12=3.14/4 XD2 D= m =123.6mm =>ANS 2. Write down the applications of fluid system. Fluid power technology over the years has continuous development involved to the applications of pneumatic and hydraulic system in several areas like i. manufacturing ii. process industries iii. transportation system and iv. utilities 3. What is called hydraulic accumulator? 45

46 A hydraulic accumulator is an energy storage reservoir in which a fluid is held under pressure by compressed gas or a spring or araised weight. 4. What are the uses of pilot-operated values? Pilot operated values are essential to control large values as the solenoid required as compared to the actual value would be bigger sometimes solenoid or manual operated values. The force required to move the spool or poppet may be too high. 5. What is meant by actuators? Actuator is a device used as an output device to do useful work. Work produced by both hydraulic and pneumatic system is in the form of moving gripping and applying force to an object. 6. Explaion the working principle of pneumatic diaphragm actuator. Figure shows a simple construction of typical control value using a pneumatic diaphragm actuator attached to drive the system which is used to control the flow. The operation of pneumatic diaphragm actuator is explained in the previous section. The operation diaphragm actuator moves the inner valve plug and varies when the steam 46

47 and the plugs moves up and down. The shape of the plug determines the amount of actual opening the value. 7. Differentiate between Vane actuator and Rack and pinion actuator. Vane actuator Rack and pinion actuator 1. The vane swings and rotates in a normal and reverse direction when the fluid/air pressure act on it and hence the torque is transmitted to the output shaft attached with the vane. 2. Vane actuator are limited in rotation and most do not exceed Less expensive than the rack and pinion actuators 4. Less maintenance is required 5. High torque-to-two size 6. Zero backlash is possible 7. Less accuracy 8. High loads are not possible to apply 9. The rack most back and forth when fluid /air pressure act on the piston in a cylinder and hence the torque is transmitted to the output shaft via pinion 10. This type of actuators are capable of providing one revolution or more 11. More expensive 12. More maintenance is required 13. Less torque-to-two size 14. Zero back clash is not possible 15. More accuracy 16. High loads are possible to apply 8. What are the various types of gear trains? i. simple gear train ii. compound gear train iii. reverted gear train iv. planetary gear train 9. Classify belts. i. flat belt ii. v- belt iii. round belt 47

48 iv. timing belt 10. What is bearing? A bearing is a device allows constrained relative motion between two or more parts, typically rotations or linear movements. The bearings are used in variety of machine elements to guide and allow the relative motion between the parts with minimum friction and maximum accuracy. 11. What are types of radial ball bearings? i. deep groove ball bearing ii. self aligning ball bearing iii. angular contact ball bearing iv. filling notch bearing v. counter bore bearing vi. double row bearing 12. Define holding torque? Therminmum torque that can be applied to a powdered motor without moving it from its rest and causing spindle motion. 13. at what conditions SPDT, DPST, and DPDT switches are used? a. SPDT (single pole double throw); when we required ON and OFF operation as the circuit is activated DPST is used. b. DPST switches; when we need to turn two separate circuits ON and OFF simultaneously with a single switch, DPST is used. c. DPDT switches; when a switch is turned ON and OFF between N and O with double pole switches, DPDT is used. 14. What are the types of field effect transistor? 48

49 i. junction field effect transistor (JFET) ii. metal oxide semiconductor field effect transistor(mosfet) 15. Classify electrical motors. i. AC MOTORS ii.dc MOTORS 16. What is stepper motor? A stepper motor is a rotating machine which converts DC voltage pulse into a series of discrete rotational steps. Each step position is equilibrium without further excitation, this make it ideally suitable for use with a digital control. 17. What are the two types of MOSFETS? 1. n-channel MOSFETS 2. p-channel MOSFETS 18. Draw the symbol of SCR. A K G 49

50 UNIT-2 PART-B 1. Explain various types of CAM followers. [Even-2008] Types of cam followers (1) Knife edge follower This is the simplest type is not often used due to rapid rate of water. When it is adopted it is usually for reciprocating motion, running in slides and there is considerable side thrust from the cam. Figure shows the knife edge follower. (2)Flat foot (or) mushroom follower; This type of follower has a flat surface to connect with the cam. the problem of wear is not as great as with the knife edge follower. Since the point of contact between the cam and follower will move across the face of the follower according to the change of shape of the cam. This type of follower is used in IC engines. Figure shows this type of follower. 50

51 (3)Roller follower; This type of follower has roller attachment with it which is in contact with the cam and a roll over it.it eliminates the problem of rapid wear since the sliding effect is largely replaced by a roller action. Figure shows this type of follower. (4)Offset follower; 51

52 If the line of movement of the roller follower or flat faced follower is offset from the center of the rotation of the cam. The follower is known as offset follower. Figure shows this type of follower. (5)Oscillating follower; Oscillating follower is pivoted at a suitable point on the frame and oscillates as the cam makes the rotary motion as shown in the figure. There are four type of oscillating follower depending upon the shape of the end of the followers. a. spherical faced oscillating follower b. flat faced oscillating follower c. roller faced oscillating follower d. edge faced oscillating follower 2. Explain the various types of ball and roller bearings [Even-2008] Types of ball bearing; Deep grove ball bearing This is most common type of bearing and widely used. A deep groove radial is one in which the more dimensional are closes to the dimensions of the balls 52

53 that mesh in it. Deep-groove bearing have good radial load carrying and moderate axial load capacity. Filling-notch or filling-slot ball bearing A filling-notch radial bearing is one in which the inner and other outer races are notched show that when they are aligned balls are be slipped in the slot in order to fall the bearing. It has higher radial carrying capacity than deep grove bearings and has poor axial load capacity. Angular contact ball bearing; An angular contact ball bearing uses axially asymmetric race. An axial load passes in a straight line through the bearing. Whereas radial load takes an oblique path that tends to want to separate the races axially. So the angle of contact on the inner race is the same as the on the outer race angular contact bearing better support both the radial and axial load. 53

54 Double row ball bearing Double row ball bearings have two rows of balls and are made with either radial or angular contact between the balls and race. These bearing are able to with stand higher radial load and thrust load either direction compared to single row bearing. Self aligning ball bearing; Self aligning ball bearings are constructed with the inner ring and assembly contained within an outer ring that has a spherical race way. This construction allows the bearing to tolerate a small angular misalignment resulting from deflection or improper mounting. These bearing are able to withstand moderate radial loads and fairly poor axial loads. 54

55 Thrust, grooved race ball bearing; These ball bearing uses side by side race. An axial load is transmitted directly through the bearing. While a radial load poorly supported tends to separate the race and anything other than a small radial load is likely to damage the bearing. Types of roller bearing; *Straight roller bearing. Straight roller bearing use cylinder of slightly greater length than diameter. These bearing have higher radial load capacity then ball bearing of same size but a low axial capacity and higher friction under axial load. If the inner and outer race are misaligned the bearing capacity often drops quickly when compare to ball bearing 55

56 Tapper roller bearing. Tapper roller bearing are use conical roller that run on conical race. Most roller bearing only takes radial loads but tapered roller bearing supported both radial and axial loads and generally can carry higher load than ball bearing due to greater contact area. for example the wheel bearing of most cars, truck busses, and so on. Needle roller bearing; Needle roller bearing use very long and thin cylinders. Often the end of the roller tapper to pointer and these are used to keep the roller captive or they may be hemispherical are not capture but held by the shaft itself or a similar arrangement. Since the roller are thin. The outside diameter of the bearing is slightly larger than the hole in the riddle. 3. Explain the working principle of brushless permanent magnet DC motor. 56

57 Brushless permanent magnet DC motor. The commutators and the brushes suffer from wears and produce sparks often when they contact. Hence brushless permanent magnet DC motor is designed. In conventional DC motor, the magnet is fixed and the current carrying conductors are made to move. In the brushless permanent magnet DC motor, the current carrying conductors are fixed and the magnet moves. Therotqr is a ferrite or ceramic permanent magnet The basic form is shown in the figure, the current to the stator coil is switched electronically and it Controlled based on the position of the rotor is that there are forces always acting on the magnet causing it to rotate in the same direction. 57

58 To sense the position of rotor hall sensors are cued it initiator the switching by transistors. The sensors are placed around the stators. The figure shows the transistor switching circuits and the switching sequence is also shown Go for position Advantages; Sensor signal Transistors A b c A+ A+ B+ B+ C+ C+ BCCAAB- Entire the circuit is available in Ic form. Low maintenance is sufficient. Reliability is good. High speed. 4. Explain the specification of a stepper motor in detail. [Odd-2007] 58

59 Two phase motor have four connecting for signals to generate the switching sequence. The following circuit contains Q1 to Q8, totally & transistors. The following table explains the switching sequence needed to carry out four steps. For Bipolar stopper: Table1: switching sequence for full stapping. Step No Transistor Q1&Q4 Q4&Q3 Q5&Q6 Q6&Q7 ON ON OFF OFF OFF OFF ON ON ON OFF OFF ON OFF ON ON OFF Table one gives the sequence needed for transistors to carry out the 4 steps (step No1, step No4). The same sequence needed for the transistors to carry out the 4 steps. The same sequence is repeated for forth steps. This sequence is used for clockwise rotation. This sequence is reversed for anticlockwise rotation. 59

60 Finer resolution can be obtained using half step rotation. Compared with full step rotation. The switching sequence needed for half step rotation, is given below For bipolar stepper motor; Table2: switching sequence for half stepping Step No Q1&Q4 ON ON ON OFF OFF OFF OFF OFF Transistor Q2&Q3 Q5&Q8 OFF ON OFF OFF OFF OFF OFF OFF ON OFF ON OFF ON ON OFF ON Q6&Q7 OFF OFF ON ON ON OFF OFF OFF Uniform stepper motor: Two phase motor as known as unipolar f they have side connecting wires for the switching sequence generating. Each coil has two centre tap. It is shown in following figure. 60

61 Table3: switching sequence for full stepping unipolar stepper motor. Step No Transistor Q1 Q2 Q3 Q4 1 ON OFF ON OFF 2 ON OFF OFF ON 3 OFF ON OFF ON 4 OFF ON ON OFF Following table 4 shows the switching sequence for half stepping unipolar stepper motor. Table 4: the switching sequence for half stepping unipolar stepper motor. STEP No Transistor Q1 ON ON OFF OFF OFF OFF OFF Q2 OFF OFF OFF OFF ON ON ON Q3 ON OFF OFF OFF OFF OFF ON 61 Q4 OFF OFF ON ON ON OFF OFF

62 8 OFF OFF ON OFF The above sequence is cured for clockwise rotation. The above sequence for reversed for anticlockwise rotation. Stepper motor Claire circuit is available in the IC formats SAA Diode across the coil is used to prevent current in the reverse direction and to provide the protection. Internal block diagram of IC SAA 1027 is shown below 5. Explain thyristors and traces in detail. [Even-2006] Thyristors: The Thyristors or silicon controlled rectifier (SCR) is a three terminal four layer Thyristors. In addition to anode and cathode, the SCR has a gates terminate. The gate terminal is used to fire but not open, on SCR, SCR are open by reducing current flow below holding current. 62

63 SCR can work as an ON-OFF switch. A short LHS pulse of control current applied to the gate will switch the SCR in to conduction. Dropping cathode to anode current below the holding current turns the SCR off. Voltage control by Thyristors: When the sine wave AC input is applied across the Thyristors the effect is show below. Forward breakdown across when the breakdown voltage is reached. Then the voltage across the device remains low. Thyristors D.C control: The circuit shows the D.C control by Thyristors. Here the Thyristors is operated by as a switch by using the gate to switch the devise ON or OFF. An alternating signal is applied to the gate. By using this, the supply voltage is chopped and an inter mitten voltage is produced. 63

64 The average value of the D.C output voltage is varied and controlled by an alternating signal to the gate. Phase control circuit using thyristor: 64

65 Figure shows a half wave, variable resistance phase control circuit. The alternating current is applied across the load. R is a potentiometer. R2 is known as current limiting resistor. R1 is used to set the level at which the thyristors is trigged the diode is used to prevent the negative cycle of AC voltage begin applied to the gate. R1 is adjusted to trigger at any point between 0 to 90. When the thyristors is trigged at 0. It conducts for the entire positive half cycle and maximum power is delivered to the load. If the trigging is delayed, then the power delivered to the load is reduced. Application of SCR: 65

66 1. Motor speed control. 2. Light diming control. 3. Phase control. 4. Heater control. 5. Battery charger. 6. Inverter. 7. Rectifier power supply. 8. Relay control Are some of the applications of SCR. Triac: It is the three terminal devices, which can conducted in either direction when trigged either positive or negative pulse irrespective of the polarity of the voltage across its main terminals. Trice the behaves like two SCR s connected in parallel but is opposite directions with common terminal. The traces are available with current rating up to 25A and voltage rating up to 500 volt. It symbol is shown below. MT 2 G MT 1 MT 1: Main terminal 1 MT 2: Main terminal 2 G: Gate terminal VI characteristics of a triac: It gives relationship between the triac current and voltage applied across, the two main terminals. Triac is operated in two ways. Case1: M.T.2 and gate both are positive with respect to M.T.1 Case2: M.T.2 and gate both are negative with respect to M.T.1 In case 1, trice current flows from the M.T.2 to the M.T.1 66

67 In case 2, the trice current flows from M.T.1 to M.T.2 A VI characteristic of a triac is shown below; The following points are noted from the graph. The cure obac and odef are symmetric and identical to the forward characteristics of SCR. The trice is OFF until the applied voltage of the either polarity exceeds the breakdown voltage. As the applied voltage of either polarity exceeds the breakdown voltage the triac turns ON and the voltage drop across the trice decreases to a low value. The trice current increases to a value which is determine by the supply voltage and load resistance. As the value of gate current is increased above zero, the break voltage is covered. When the gate current of a suitable value is applied, the triac turns ON at much lower breakdown voltage. 67

68 UNIT-III PART-A 1) What are the characteristics of negative feedback? (Odd-2007) * Reduce the noise distortion etc * 180 phase shift to be provided 2) Write the analogous electrical element in force voltage analogy for the element of mechanical translation system. (Odd-2007) It represents the types of force experienced when the object is moved against frictional force or when the object is pushed through a fluid. It shown below Fluid resistance F Dash pot F [Input] X [Output] Dash pot; Figure represents the damping force which slows down moving object which convicts of a piston needs the fluid moving in closed cylinder Movement of the piston needs the fluid on one side of the piston to flow through or past the+ position. Resistive force is produced due to this flow. Ideally the damping force f is directly proportional to the velocity v of the piston, so Fαv F=c.v Where, c-constant V=c. dx/dt 3) Explain the terms hydraulic resistance and hydraulic capacitance. [Even-2006] Hydraulic resistance; 68

69 P1 P2 Hydraulic resistance to flow which occurs an a result of liquid flowing through valves or changer in diameter of the pipe RhQ=P1-P2 P1-P2=Pl difference Rh-hydraulic resistance Q-volume rate of flow of liquid Hydraulic linear resistance can be measured with orderly flow through capillary tucks. Non-linear resistance can be measured with flow through sharp edged orifices HYDRAULIC CAPACITANCE: Q1 Q1-Q2=Ch.dp/dt P=1/Ch (Q1-Q2) dt 4) Why derivative controllers are never used alone? (Even-2008) Derivative controllers operators on rate of change of euro (de/dt).it is always used completely with p or p1 controller 5) Give an example for two step mode control unit. [Odd-2008] Room heating system is an example for two step mode control unit. 6) Derive the equation for a translation mechanical system model with spring and mass. 69

70 Spring: It represents the stiffness of a system.the stiffens is given by the relationship between the force (f) used to extend or compress a spring and the extension or compression. Fαx F=kx F F Input X Spring Output Mass: F Mass Acceleration The relationship between the force f & the acceleration A is given as, F=ma Where; M-mass=const of proportionality between F and a A -dv/vt=the rate of change of velocity here v=dx/dt So, a=d/dt (dx/dt) =d2x/dt2 So, f=m.d2x/dt2 7) Write the analogous symbol in force voltage analog for the element of mechanical translation system. It represents the types of force experienced when the object is moved against friction force or when the object through a fluids. 8) What are the characteristics of negative feedback? [Odd-2009] 70

71 *Reduce the noise, distortion etc *180` phase shift to be provided 9) Convert the spring mass damper system into an equivalent electrical system. Write down the system equation. F(t)=mdu/dt+Bu+1/k u dt v(t)=ldi/dt+ri+1/c i dt 10) What is the various control modes used in mechatronics control system. [Even-2010] # Two step mode #Proportional control mode #Integral control mode #Derivative control mode #PI control mode #PD control mode #PID control mode. 11) Draw the torsional spring mass system. Write down the system equation. [Even-2010] 71

72 Here a torque is used to rotate a mass at the end of a shaft its differential equation is given as T=I d2θ /dt2+c.dθ/dt+kθ 12) What is meant by digital logic circuit? [Odd-2010] Digital logic control is the process of digital logic components to perform a specified function and data manipulation and communication function and the interconnection b/w them. Device such as and gates or gates and x-or gates are basic blokes, which are together with device like flip-flop, shift resistors etc are used in all digital logic circuits. 13) Write the differential equation for the system. [Odd-2011] 72

73 Ans F(t)=1/K1 y1dt+1/k2 Y2dt+M dy/dt F(t)=1/k1 u(t)dt+1/k2 u dt +M du(t)/dt 14) What are the steps involved in the equation of a digital controller? The up is initiate the control mode to process the ever.it is decided by the up program. The clock signal is used to synchronize the operation in the ADC, DAC & microprocessor. 73

74 UNIT-III PART-B 1) Derive a mathematical model for a machines mounted on the ground to study the effects of ground distillation on the machine bed displacement. [Odd-2007] The following figure shows a mathematical model for a machine mounted on the ground and could be used as a basis for studying the effect of ground disturbance on the displacement of a machine bed. The procedure for the analysis of this model is just the same as the analysis for the simple spring dash pot man model. Ground Input force A free body diagram can be drawn for each mass in the system. In this diagram each mass is shown independently and just the forces acting on it are also shown. Then for each mass the resultant of the forces acting on it is equated to the product of the mass and the acceleration of the mass. 2) Compare the control system performance for a system with proportional control and a system with a integral control. [Odd-2007] In the mode the relationship b/w input & output of the controller is linear. The output of the directly proportional to the error. Here, y α e output proportional to the error Y=kp.e Where, y=output e=error signal kp =proportional sensitivity It is used to adjust the gain of the controller Kp=100/proportional band 74

75 Proportional band =100/Kp Y= [100/proportional band] e+f PROPORTIONAL BAND SHOWN BELOW; Here, F-bias output It there is no error then, the o/p of the controller is equal to f DRAW BACK; It will not maintain the controlled variable at desired set point. INTEGRAL CONROL MODE; The offset error in the proportional controller is eliminated by the integral control mode. It is also called as reset mode the reason is after a load change, it returns the controller variable to the set point and removes offset There, y=1/t T=time setting of the controller y=o/p e=error f=bias o/p If a device where o/p is time integral of the derivation Error Output Time Time At time=0 APPLICATION 75

76 *Flow control system *Valve position control system 3) Derive the differential equation governing the mechanical system of an electric motor. [Odd-2007] *In dc motor used to conduct an electrical signal into mechanical output. *Due to the current through the armature coil the shaft is rotated so load is also rotated. *Armature coil is fuse to rotate. It is located in the magnetic field which is provided by the current through the field coil. *when the current Ia flour through the armature coil, same face will be acting on the coil,so it is located F-force Ia-current flows through the armature coil L-armature coil length B-flux density F- B. Ia.L N=no of turns 76

77 T=torque due to the force on the armature coil F=B.Ia.L T=Fx (breath of coil) T=B.Ia.LN*(breath of coil) TαBIa T-k1 BIa=k3Ia When the armature coil is rotated in a magnetic field, a voltage is induced in it due to electromagnetic induction. It is in the direction to oppose the change producing it. This called as back emf. It is proportional to Bw VbαBω Vb=KbBω Ω=shaft angular velocity Kb=constant In armature controlled motor the field current it is constant and the motor is controlled by adjusting Va Vb α ω Vb=k2ω Va-Vb=La.dia/dt + Ra.Ia Put Vb in 1 Va-K2w=La dia/dt + RaIa Put T=K3Ia Dω/dt=angular acceleration I dω/dt=k3ia-ktω IN FIELD CONTROLLED MOTOR; 77

78 Here the armature current is constant and the field voltage is varied to control motor. Vf=Rf If +Lf dif/dt T If T=kFIf Net torque= kfif-ktω Idw/dt=kf If KTω 4) Explain the characteristics of p10 controller. [Odd-2007] It is the combination of proportional integral and derivative control action. Generally it is output is given as Y=kp [e + 1/T +f -v0=(rf/r1)ve+(rf/r1) 1/R1C1 Rf/R1==Kp=proportional gain constant 1/R1C1= integral gain constant RD CD= derivative gain constant. In block diagram op amp (1) is in proportional control mode op amp(3) is in integral control mode op-amp (4) is in derivative control mode op amp (5) is in adder circuit. T BIa T=K1BIa=K3Ia When, the armature coil is rotated in a magnetic field, a voltage is induced in it due to electromagnetic induction. It is in the direction to oppose the change producing it. This is called as back emf. It is proportional to Bw. Vb α Bw 78

79 Vb = KbBw W-shaft angular velocity. Kb-constant In armature controlled motor the field current If is constant and the motor is controlled by adjusting Va Vb α w Vb = K2w [ K2- constant] Va Vb = La.dIa/dt+Ra.Ia..1 Put Vb in 1 Va K2w = La dia / dt+ Ra Ia [Net torque = T-ktw] Put T=K3Ia dw/dt=angular acceleration I dw/dt = K3Ia-Ktw [ Kt- constant] In extance (flow rate change is slow so it can be neglected) Q1-Q2=Ch dp/dt P1-P2=Ph.Q2 P1-P2= Ps due to the Kt of the liquid P1-P2=hρg Q= hρg/rh Sub in 1 Q1- hρg/rh=ch. d(hρg)/dt CA=A/ρg Q1=A.dh/dt + hρg/rh 79

80 So the liquid height in the container depends on the rate of input of liquid into container. PNEUMATIC SYSTEM; It consists of 1).capacitor-( capacitance is provided by the bellows itself) 2) Resistor- (resistance is provided by a construction which can restrict the rate of flow of gas into the bellows) 3) Inertance0-(neglected because the flow rate changes slowly) The output of these 3 op amps are combined in the inverting (-) terminal of the adder circuit. So the output is given as V0 Advantage: It is a fast controller Disadvantage: It is design is a complex one. 5) Explain fluid system building blocks. [Even-08] HYDRAULIC SYSTEM 80

81 Where liquids entering and leaving the container.it consists of 1) Capacitor 2) Resistor P1-pl prior to the constriction P2-ps after constriction The gas entered into cylinder bellow will remain in it Mass flow rate R m p1-p2 m1-m2=(cp1-cp2) dp2/dt P1-P2/R=(CP1-CP2) dp2/dt P1=R(CP1+CP2) dp2/dt+p2 Bellows are like a spring so F=Kx P2=F/A A=area of cross section Put 2 in 1 P1=R(Cp1+CP2) K/A dx/dt +Kx/A Generally Cp1=ρ. dv/dp Here CP1=ρ dv/dp2 V=Ax P2=Kx/A Cp1=ρ. Adx/d(Kx/A) =ρa/(k/a).dx/dx 81

82 Cp1=Ρa2/k Cp2=v/RT=Ax/RT Cp2=Ax/RT 6) Explain the electronic professional derivative (PD) controller with necessary circuit diagram. (Even-2008) It combines proportional and derivative control action generally the equation of PD Controller is Y=kp[e+Tp de/dt]+f Vo= [R1/R2+R3]Ve + [R1/R2+R3]CR3de/dt+voω Kp =R1/R2+R3=proportional gain constant Kr=CR3=derivative gain constant Sometimes it fails to remove the offset. In is also known as late control action. In controller the o/p is valid with respect to rate of change of actuating ever signal. 82 this

83 It shows the how o/p valid due to change in even. 7) Explain the building blocks for thermal system. [Even-2008] *Resistance capacitance is the two building blocks of thermal system. Thermal Resistance:- (R) If Q= rate of flow of heat T1-T2= Temperature difference Q= T1-T2/R R value depends, mode of heat transfer. If construction through a solid, for Unidirectional conduction Q= AK (T1-T2/L) A-Area of consecution of the material K-Thermal conductivity Here, R=>L/AK If the mode of heat Transfer is convection, then Q=AK(T1-T2) A-area h-ht.tr co-efficient R=>1/Ah Thermal capacitance: If, Q1-rate of flow of ht into a system Q2-rate of flow of ht out from a system 83

84 Rate of change of Internal Energy=Q1-Q2 Rate of change of Internal energy =(mc) rate of change of temperature Q1-Q2=mc dt/dt Q1-Q2=c. dt/dt C-Thermal capacitance. Building Up a model for a Thermal system:- T-Temp TL-Temperature of liquid Q-The net rate of flow of heat Q1-Q2= c.dt/dt If, Q1=Q; Q2=0 then Q= c.dt/dt Q=TL-T/R

85 1=2 so, cdt/dt=tl-t/r TL= Rc dt/dt+t This is the first order differential Equation. 8. Explain PI controller with necessary circuit diagrams.[ Odd-2008] Block diagram:- Generally, Its equation is given as, Y=KP[e+1/T e.dt]+f 85

86 Here, It can be written as, V0= (R/R1)Ve+1/R1c(R/R1) Ve dt+v0(0) V0=> (R/R1) [Ve+1/R1c ve dt]+v0(0) A hot object with capacitance C and Temperature T1 cods in a large Room at Temperature Ta, If the Thermal system has a Resistance R, desire an equation desailing how the Temperature of the hot object changes with time and give an electrical analogue of the system 9. Propose a model for a stepped shaft used to rotate a man and derive an equation relating the Input Torque and the angular rotation neglect damping Effect.. [Odd-2008] Its Building Block model is shown below Torsion Resistance Here, a Torque is used to rotate a means at the end of a shaft Its differential Equation is given as, T=I d2θ/dt2 + Cdθ/dt + Kθ 86

87 10. Desire a mathematical model for a resistor inductor capacitor system Using Kerch off s law. This is an Example for resistor inductor- capacitor system. Applying KVL, V=VR+VL+VC VR=IR VL=L.dI/dt But, I=c.dvc/dt.. 1 di/dt= c. d (dvc/dt) / dt di/dt= c.d²vc/dt².. 2 V= IR+L.dI/dt+Vc Replacing I and di/dy by 1+2 Now; V= RC dvc/dt+i. c d²vc/dt²+vc The given relationship between Input & output Vc. This is second order differential equation 11. Proposea model for a stepped shaft used to rotate a mans and desire an equation relating the I/P torque and angular rotation Neglect damping. [Even2010] 87

88 Same as 3rd Qtn 12) Explain in detail adaptive control system. [Even-2010] * The control system which can adapt changes and it can changes its parameter depends the situation. It is known as adaptive control system. * In normal control system P,O,I Constance are fixed. But in, adaptive control system, proportional, derivative, integral Constance can be changed. * Microprocessor is the heart of this control system. By using program, it can change the control parameter based on the situation. Some of the following adaptive control systems are given below Gain scheduled control:it is also known as pre-programmed adaptive control. This type of control system is shown below. The control system is used to control the positioning of the load. Here, system parameter for various load values is determined previously and there are stored in the memory. So this system measures the loaf value and it can select the corresponding system parameters. By using this system for example proportional constant values can be adjusted. Advantage: *Parameters can be changed quickly based on the condition. Disadvantage: *The system parameters have to be determined for various operating conditions. Self turning control: It is used in PID controllers. This control is also known as auto turning control. Initially the response is compared with the desired value and controlling parameters are adjusted. This system can continuously tune its own parameters based on monitoring the controlling variables and the output. 88

89 Model reference adaptive system: Here the set value is used as input to practical system and the model system. The outputs are measured from these systems. The difference between these outputs is used to used to adjusted the controller parameters 13. Derive a mathematical model for a spring mass damper system. A mass a spring and dash pot are combined in many system. The net force applied to mass m=f-kx-cv The net force is the force applied to the mass to accelerate it So the net force applied to mass =ma, a= d2x/dt2 V=dx/dt We get F= d2x/dt2 + kx +c. dx/dt This system is called as differential equation. It gives the relationship between the input of force F to the system and the o/p of displacement x In this equation d2x/dt2 term is there. So it is known as second order differential equation. If only dx/dt term is there that is known as first order differential equation. 14. Compare the control system performance for a system with derived control and a system with proportional control.[odd-2010] Proportional control mode; In this mode the relationship between input and output of the controller is linear. The o/p is linear. The o/p f the controller is directly proportional to the surface. 89

90 Here y e output proportional to the Error. Y=Kᵖe Where y-o/p e-error signsal Kᵖ- proportional sensitive It is used to adjust the gain of the controller Kᵖ=100 / proportional band Proportional band =100 / kᵖ Y= [100 / proportional band] e+f Here f bias output If there is no error the the o/p of the controller is equal to f Derivative control mode: In this mode y= Td dc/dt Td- time derivative Y - Output e- Error Derivate econtroll mode is used to provide high sensitive. It i used always combinely with P or PI controller. It is operater on rate of change of error d/dt Fig shows the constant rate of change of error with time. If it is constant the controller is also constant 15. With a neat circuit diagram explain the working of PID controller. [Odd-2010] 90

91 PID controller algorithm involves three separate constant parameters and is accordingly sometimes called three mode controllers. The proportional the integral and derivative values denoted by P,I,D PID controller is the most commonly used a feedback controller A PID controller calculates an error value as the difference between a measured process variable and desired set point The controller attempts to minimize the error by adjusting the process control inputs. PID values can be interpreted in terms of time. P depends on the present error m, I on the accumulation of past errors and D is a prediction on future errors based on the current rate of change. The weighted sum of their three actions is used to adjust the process via a control element such as the position of a control value or the power supply of a heating element. 91

92 UNIT-IV PART-A 1. Define plc. A programmable logic controller is a microprocessor based controller that uses a programmable memory to store instruction and implement function and arithmetic in order to control machines and process 2. What are the components of a plc? i. Control processing unit ii. Input/output modules iii. Programmer/monitor 3. Draw the block diagram of plc. 4. What is the function of programming devices? The programming device is cureel to enter the required program using ladder logic into the memory of the processor 92

93 5. Define CPU. The CPU is the brain of the plc consist of microprocessor which interprets the input signal and carriers out the control action according to the program stored in the memory 6. List out the various programming device i. ii. iii. Key broad Lcd unit A personal computer with appropriate software 7. Define memory unit The area of the CPU is which data and information is stored and retrieved it holds the system software and user program 8. What is the type of memory? i. ii. Random access memory (RAM), Read only memory (ROM), a) Programmable read only memory (PROM), b) EPROM and EEPROM. 9. Compare plc with compute PLC 1. Plc is the very compact and not affected by the vibration and electrical affect etc. 2. Plc can be easily handled by unskilled persons. COMPUTER 1. Computer is very less compactable 2. Computers need the skilled persons with knowledge and software to handle 93

94 10. What are the input / output devices used? Input device i. ii. iii. Various sensors Switches like mechanical, proximity and photos electric Encoders Output device i. ii. iii. iv. Motor Control valves Lumps, light etc Alarm 11. List down input/output modules interface s/no Input interfaces Output interfaces 1 Dc input unit Relay output unit 2 Ac input unit Transistor output unit 3 Adc interface Dac interface 12. Define program scanning? The plc control the whole process by reading the data from the input and the output is energized and de energized according to the user program stored in the memory. This process is known as program scan. 13. Draw the ladder diagram and truth table of NAND gate? 94

95 14. List out the different types of timer? 1. ON delay (Ton), 2. OFF delay (T off), 3. Retentive timer (RTO). 15. What is mean by retentive timer? Retentive on delay timer (RTO) will hole its accumulated value when the timer runs goes factor and will continue timing where it left OFF when the timer runs goes true again. 16. What are counter? Counter allow a number of occurrences of input signals to count or record the number of times some event occurs.plc includes some form of counting elements and are set to some present number value. 17. Write down the various types of counters? 1. down counter 2. up counter. 18. What are the factors to be considered for selecting PLC? [Odd 2004 & 2007] 1. System definition. 2. Choosing the input and output hardware, 3. Analogue input output module, 95

96 4. Input and output timing consideration. 5. Conversion speed, 6. Analog closed control, 7. Communication and choose the correct processor. 19. List out the general applications of PLCs for control? 1. Control of process motor, vibrating machine 2. Control of two pneumatic piston, 3. Dection, sorting and packing unit. 20. Draw the ladder runs to represent two switches are normally open and both have to be closed for a motor to operate? [Even-2008&Odd-2008] IN 1 and IN 2-input switches M-motor 21. Draw the ladder runs to represent a latch circuit? [Even-2006] O l output IN 1-push button. 22. What is the need of counter? Show the basics counting program using a ladder diagram? [Even-2006] IN 1-input C 1-count O 1-output 23. How PLC differ from relay logic? i. Rewinding should be easily alone in PLC i. ii. no vertical connections are allowed In plc, there must always be one output on each line 24. Derive a timing circuit that will switch on output on for 1 sec then off for 20 sec and so on 96

97 I1-input T1-timer 1 for 1 sec T2-timer 2 for 20 sec m1, m2-memory coil O1- output (light) 25. What are the logic functions that can be obtained by using switches in series? AND logic: I1, I2- input O1-output PROBLEM:-1 There are three mixing devices on processing lines A, B, C after the process begins. Mixer A is to start, after7sec is elapsed, next mixer B is to start,3.6sec after A. mixer C is to start 5sec after B all remains ON until a master enable switch is turned OFF. Input IN001-main switch (start IS switch) Memory coil: m1 OUTPUT: H001-motor A H002-motor B H003-motor C 97

98 PROBLEM:-2 A work piece is loaded on a conveyor belt and operator between two limits of towel A and B when limits switch at station A is activated the conveyor moves forward. When limits switch at station B is activated the conveyor change directions. Pressing the start button causes the motor to run in the forward direction and pressing the stop button the motor. Create the ladder logic diagram and explain 98

99 Ls1-limit switch A Ls2-limit switch B O1- conveyor moves forward O2- conveyor moves reverse O3-motor run L1-start button L2-stop button PROBLEM NO:-3 Devise a system using a PLC that could be used with a conveyor belt which is used to move an item to work station.the presence of the item at the work station is detected by means of breaking a contact activated by a beam of light to a photo sensor. There it stops for 100sec for an operation to be carried out and then start moving. The motor for the belt is started by a normally open start switch and stopped by normally closed switch. L1-photo sensor output L2-start button for motor L3-stop button M1, M2-memory coil T1-timer for 100 sec PROBLEM: 4 Devise a circuit that could be used with a domestic washing machine to switch on pump to pump water for 100 sec into a machine. Then switch off the pump and switch on a heater for 50 sec to heat the water. The heater in then switched off and another pump is switched on for 100 sec to empty the water from the machine. L1-start 99

100 L2-stop O1-pump O2-heater O3-pump T1-timer 1(100 sec) T2-timer 2(50 sec) T3-timer 3(100 sec) M1, M2 M3- memory coil 100

101 101

102 UNIT-IV PART-B 1.Write a short note on timers. [Odd-2004] PLC Timer functions: Timer Non-retentive retentive A single input timer called a non retentive timer is used in some PLCs. An examples is shown in fig 4.15 Non retentive number: Energizing IN 1 causes the timer to run for 3 seconds. At the end of L1 seconds that goes ON. When the input is de energized the output goes OFF and the timer result to 0. If the input IN1 is turned OFF during the timer interval (for example after 1.5 seconds) the timer reset to 0.in this case the output will not turned ON There are operational disadvantages of the single input timer. The fig 4.16 shows the double input timer or retentive timer. Timing diagram for non-retentive timer Examples 1: Example 2: Retentive timer: Double input timer on retentive timer The fig includes enable reset line. Which allows the timer to run when energized.when energized the timer kept at 0 or reset to 0.the upper line causes the timer to run when timer is enable. When enabled, the timer runs as long as the run input is energized. If RUN is energized while the timer is running. The timing stops where it is and does not reset to 0 102

103 Timing diagram for retentive timer Example 1: Examples 2:- Two other timer function are included is some PLCs. TIME DELAY ON AND TIME DELAY OFF 103

104 The different from of timer that can be found with PLC in the figure. ON delay timer:an examples of an ON delay timer is show in the fig. the timer is energized when the input IN becomes energized. The timer running after some present time the timer closes the timer contact on rung 2 as shown in the timing diagram fig. The timer reset when the input Ln 1 goes off. OFF delay timer 104

105 An example of off delay timer is shown in figure. When the contact LN 1 is closed the contact will energized the timer T1 and helds the output lamp ON for specified set value of 10 sec. the action of an OFF delay timer is to delay setting the lamp OFF. Example: For a grinding operation in a metal part the coolent flow on the part must be ON for an interval before the grinding process starts when the process circuit is turned ON the coolant motor (CM) is turned ON. 18 seconds later the grinding process (GM) starts. The PLC program for this process is shown in the figure. 105

106 Input (1) IN 1 Output (1) coolant motor (CM) (2) Grinding processor (GM) The sequence for this example is as follows, (i) When the switch IN 1 is closed, CM goes ON (ii) At the same time of CM ON, timer starts running (iii) 18 sec later GM goes ON 106

107 (iv) Opening the switch IN 1 CM and GM and GM turns OFF. Example: A motor and its lubrication pump motor are both running lubrication for main motor bearing is required during motor coast down. After the main motor is shunt off the lubricating pumps remains ON for a timer corresponding to coast down time. In this example a lubricating pumps remains ON for 20 sec after the main system is shunt down. Input: (1) IN 1 Output: (1) O 1 Motor (2)O 2 Lubricating pumps. 2. What is mean by internal relays? Explain [Even-2008] Internal relays: Most PLCs are having an area of the memory allocated for internal storage that is used to hold data. Which behave like relays being able to be switched ON or OFF but for only internal purpose such internal relay does not exist as real control 107

108 switching devices are nearly but in the storage memory. An internal relay output is represented using the symbols of an output device which an address to be indicated an internal relay. In many PLC, the symbols M or relay is used for indicating the internal relay and the internal relay output is represented as M or relay, etc... The internal relay is used in programmers for many purposes as follows. 1. Resetting a latch circuit 2. Push button used as the input and 3. Master controls 3. What are ladder logic programs in PLC? [Odd-2004] 1. NO vertical controls are allowed Improper PLC ladder diagram Proper PLC ladder is shown in fig. Proper PLC diagram (ii) A coil must be inserted at end of the runs (iii) All contacts must run horizontally 108

109 (iv) Only one output may be connected to a group of contacts (v) Flow must be from left to right. 4. Sketch and explain latch circuit in PLC? [Even-2005] A ladder latch circuit facilitates to hold an output energized, even the input causes the output coil. Maintain its status until a different conditions occurs which is used to reset to coil to OFF. The example given in the figure. Shows the output is set activated when the input IN 1 is set true. But the input IN 1 used here is push button. If the push button press then the contact energized then the output 1 is activated if we released the push button the output is deactivated to overcome that problem, when there is an output another contact associated with output is established through feedback contact an formulated an OR gate noe if IN, opens the circuit will still maintain the output through the feedback contact. 5. Briefly explain how arithmetic and code conversion operation executed in PLC? [Even-2005] Arithmetic instruction:conversion:plc provides conversion from BCD to binary to BCD the typical instruction for conversion is shown in the figure. Maths instruction:normally PLCs having features to carryout arithmetic operation of additions, subtraction, multiplication and division. It is important to have two source address input reading and destination address for output. The ladder runs for various arithmetic operations. Addition instructions:subtract instructions:multiply instruction:divide instruction: 109

110 UNIT-V PART-A 1.What are the changes in design or mechatronics system? (OR) Mention the stages in designing a mechatronics system. [Even-2006, Odd-2004] Need for design Analysis of problem Generation of possible solution Preparation of specification Selection of suitable solution Production of detailed design Production of working drawing Implementation of design 2. Mention any four statements about the problem definition. Mass and dimension of design Type and range of motion design Accuracy of the element Input and Output requirement of element 3. Distinguish between traditional design approach and mechatronics approach. Traditional design 1. It is based on a traditional system such as mechanical, hydraulic and pneumatic system. 2. Less flexible. 3. Less accurate. 4. More complicated mechanism in design. 5. It involves more components and moving parts. design It is based on mechanical, electronics, computer technology and control engineering. More flexible. More accurate. Less complicated mechanism in design. It involves fewer components and moving parts. 110

111 4. The design of mechatronics system different from that of traditional system. Justify. [Odd-2004] In traditional design the component are designed thoughts mechanical hydraulic or pneumatic component and principles but in mechatronics approach mechanical, electronics, computer technology and control engineering principles are included to design a system. 5. List the advantages of mechatronics design over traditional design. [Odd2008] system serves the purpose effectively with high dimensional accuracy requirement. It provides increased productivity in the industry. It provides higher flexibility by pre supplied program which facilitates small volume production cycle. It improves the life of the system by proper maintenance and timely diagnosis of the faults. It facilitates auto motion in the production assembly and quality control. 6.How a traditional design of temperature control of domestic central heating system is improve by mechatronics design? The traditional design of the temperature control for a central AC system involves a bimetallic thermostat in a closed loop control system. The basic principle behind this system is that the bending of the bimetallic stir changes as the temperature change and is used to operate an ON/OFF switch for the temperature control of the AC system. 7.What are the requirements satisfied before starting the timer? 111

112 Start the pulse applied. Check the timer whether it is PN or OFF condition. The timer should be OFF before triggering. 8.How can be delay be varied in a simple program? DELAY LOOP LDX DATA DEX BNE LOOP RTS 9.What are the advantages of PLC system in timed switch over traditional one? In PLC system the time duration can be easily adjusted by changing the time preset values in the program whereas the traditional system requires various size of the cams. 10.What is a wind screen wiper? Wind screen wiper is a device which is used to clear the front glass of car, buses, etc. during raining days. 11.What is the configuration in operating stepper motor? Full-step configuration Half step configuration 12.Write the basic steps of the program to run a stepper motor? Step 1: Advance a step by applying a data. Step 2: Call time delay routine to complete a step. Step 3: Repeat step 1 and step 2 until the required number of step completed in forward direction. 13. List out the various sensor used in engine management system. Throttle-position sensor Exhaust gas oxygen sensor Manifold absolute pressure sensor 112

113 Temperature sensor Speed / timing sensor Engine position sensor EGR value position sensor Mass air flow sensor Knock sensor 14. Compare and construct the traditional design of a watch with that of a mechatronics based digital watch. [ Odd-2007 ] Traditional approach 1. It is based on traditional mechanical elements such as gears, spring, leaves, etc. 2. It involves more complicate mechanism and moving components. 3. Input is through pre stressing of spring. 4. Timing is less accurate. approach 1. It is based on mechanical, electronics, computer technology and control engineering. 2. It involves less complicate mechanism and moving components. 3. Input is through the battery cell. 4. Timing is more accurate. 15. List down the various mechatronics elements in an automatic camera. Auto focusing mechanism control Aperture drive Shutter drive Mirror drive Lens position encoder Lens drive 113

114 Film advance mechanism control 16.What are the advantages of using a microprocessor in the phase of a mechanical controller for a car auto of an automobile? Microprocessor controller is more accurate in term of supplying proper mixture air fuel ratio based on the variation of load It also avoids detonation by getting feedback from the knock sensor placed in the engine block It involves fewer components and moving parts and hence less wear and long life 17.Identify the sensor, signal conditioner and display elements in the bourclon pressure gauge. Sensor - Bourclon tube is acting as sensor Signal conditioner - Pinion mechanism is act as signal conditioner Display element - Pointer is the display element 114

115 UNIT-V PART-B 1.What are the various stages in designing a mechatronics system? Explain. [Odd-2005 ] STAGES IN DESIGNING MECHATRONICS SYSTEM Stage 1: NEED FOR DESIGN The design process begins with a needs are usually arise from dissatisfaction with an existing situation. Needs may come from input of service personal or from a customer through sales or marketing representative. They may be reduce cost, increase reliability or performance or just change because of public has become bored with the product. Stage 2: ANALYSIS OF PROGRAM The most critical step in a design process is the analysis of the problem. The true probe is not always what it seems to be at the first glance. Its important is often overlooked because this stage requires such a small part of the total time to create the final design. It is advantageous to define the problem as broadly as possible. If the problem is not accurately defined, it will lead to a waste of time on design and will not fulfill the needs. Stage 3: PREPARATION OF SPECIFICATION The design must meet the required performance specifications. Therefore specification of the performance needs to be prepared first. This will states the problem definition of special technical terms any constrains placed on the solution and the criteria that will be used to evaluate the design. Problem statement includes all the function required of the design together with any desirable features. The following are some of the statement about the problem. 115

116 Mass and dimension of design Type and range of motion required Accuracy of the element Input and output requirement of element Inter faces Power requirements Operating requirements Relevant standards and code of practice etc. Stage 4: GENERATION OF POSSIBLE SOLUTION This stage is often known as conceptualization stage. The conceptualization step is to determine the elements, mechanism materials process of configuration that is some combination or other result in a design that satisfied the need. This is the key step for employing in ventivencess and creativity. A vital aspect of this step is synthesis in the process of taking elements of the concept and arranging them in the proper order, sized and dimension in the proper way. Outline solution are prepared for various possible models which are worked out in sufficient detail to indicate the mean of obtaining each of the required function. Stage 5: SELECTION OF SUITABLE SOLUTION (OR) EVALUATION This stage involves a thorough analysis of the design. The evaluation stage involves detailed calculations, often computer calculation of the performance of the design by using a analytical model. The various solution obtained in stage 4 are analyses and the most suitable one is selected. 116

117 Stage 6: PRODUCTION OF DETAILED DESIGN The detailed of selected design has to be worked out. It might have required the extension simulated service testing of an experiment model or a full size prototype in order to determine the optimum detail of design. Stage 7: PRODUCTION OF WORKING DRAWING The finalized drawing must be properly communicated to the person who is going to manufacture. The communication may be oral presentation or a design report. Detailed engineering drawing of each components and the assembly of the machine with complete specification for the manufacturing process are written in the design report. Stage 8: IMPLEMENTATION OF DESIGN The components as per the drawing are manufacturing and assembled as a whole system. The foresaid movement can be obtained by pneumatic cylinder which is operated by soluedid value with limits switches are used to indicate when a motion is complete. The clockwise rotation of the robot units on it base obtained from a during backward movement of the position forward and backward movement of the piston in cylinder. The upward movement of the arm can result from forward movement of the piston in a cylinder where downward movement from its retardation to forward movement of the piston and closed during backward movement of the piston in the cylinder. Figure shows a machine used of this purpose. 117

118 TRIAC OPTOSIOLATOR consist LED and TRIAC if the input of the LED is 1. It glous and activate the TRIAC to conduct the current to the soludi value. 2. Discuss mechatronics design of automobile car park system. [Even-2006] Consider an automobile car park system with barrier operated by coui insert. The system uses a PLC for its operation. There are two barrier used namely in barrier and out barrier. In barrier is used to open when the correct money is inserted while out barrier open when a car is duted in front fig shows a schematic arrangement of an automobile car park barrier. It consists of values A and B and piston cylinder arrangement. A connecting rod connects piston and barrier as shown in fig soluoid value used to movement of the piston soluoid. A is used to move the piston upward where B is used to move the piston downward limit switches are used to when current flow through A the piston cylinder moves upward and causes to barrier to rotate its pivot and rises to lot car through. 118

119 3. Discuss a mechatronics based engine management system. [Odd-2005] An electronic engine management is made up of sensor, accurate and relate. What is tied of central process called microprocessor or microcomputer. Electronic management monitors and gathers data from a number of sensors in the engine and continuously adjusts fuel supply and injection timing. This minimizes emission and maximum fuel efficiency and engine. This minizes the electronic engine management generally consist of the following basic component. An electronic control unit full delivery system shows the various components in the typical engine management system. 1. Electronic control unit [ ECU ]: The sensor feedback to the ECU to indicate how the engine running to that. The ECU makes the necessary adjustment to the operation of the fuel delivery and or ignition system. 2. Fuel delivery system: 119