Fluid Power Systems & Control

Transcription

1 Fluid Power Systems & Control K. Craig 1

2 Fluid Power Fluid Properties Fluid Mechanics Fundamentals Systems Dynamic System Modeling & Analysis Fundamentals Hydraulic Components: Valves, Pumps, Actuators Hydraulic Systems: Valve-Controlled & Pump- Controlled Integration, Modeling, & Analysis Control System Control: Feedback, Feedforward, & Observers Fluid Power Systems & Control K. Craig 2

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6 Design News June 2012 Fluid Power Systems & Control K. Craig 6

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26 References Academic: Fluid Power Fundamentals of Fluid Power and Control, J. Watton, Cambridge, Hydraulic Control Systems, H. Merritt, Wiley, Hydraulic Control Systems, N. Manring, Wiley, Modeling, Monitoring, and Diagnostic Techniques for Fluid Power Systems, J. Watton, Springer, Control of Fluid Power: Analysis and Design, D. McCloy and H.R. Martin, 2 nd Edition, Ellis Horwood, Fluid Power Systems & Control K. Craig 26

27 Industry: Fluid Power Industrial Hydraulics Manual, Eaton Corp., Electrohydraulic Proportional and Control Systems, Bosch Automation, Electrohydraulic Proportional Valves and Closed Loop Control Valves, Bosch Automation, Closed Loop Electrohydraulic Systems Manual, Vickers, Inc., Basic Electronics for Hydraulic Engineers, Eaton Corp., Hydraulics, Festo Didactic, Electrohydraulics, Festo Didactic, Fluid Power Systems & Control K. Craig 27

28 Academic: System Dynamics and Control to System Dynamics, J. Shearer, A. Murphy, and H. Richardson, Addison-Wesley, Dynamic Modeling and Control of Engineering Systems, J. Shearer, B, Kulakowski, and J. Gardner, 2 nd Edition, Prentice Hall, Modeling, Analysis, and Control of Dynamic Systems, W.J. Palm, 2 nd Edition, Wiley, Mechatronics, S. Cetinkunt, Wiley, to Fluid Mechanics, R. Fox and A. McDonald, 3 rd Edition, Wiley, Sensors and Actuators, Clarence de Silva, CRC Press, Fluid Power Systems & Control K. Craig 28

29 Advantages / Disadvantages / Challenges Fluid Power is the transmission of forces and motions using a confined, pressurized fluid. In hydraulic fluid power systems the fluid is oil, or, less commonly, water. In pneumatic fluid power systems the fluid is air. Fluid Power System Advantages High Power Density Fluid power is ideal for high speed, high force, high power applications. Compared to all other actuation technologies, including electric motors which are limited by magnetic saturation, fluid power is unsurpassed for force and power density. Fluid Power Systems & Control K. Craig 29

30 Responsiveness and Bandwidth of Operation Fluid power systems have a higher bandwidth than electric motors and can be used in applications that require fast starts, stops, and reversals, or that require high-frequency oscillations. High Accuracy and Precision Oil has a high bulk modulus; hydraulic systems can be accurately and precisely controlled. Advances in pneumatic components and control theory have opened up new opportunities for pneumatic control applications. Heat Dissipation and Lubrication Ensures Reliability Fluid circulating to and from an actuator removes heat generated by the actuator doing work, and also lubricates moving parts of the components. Fluid Power Systems & Control K. Craig 30

31 Heat is the predominant damaging mechanism in electric and electronic systems and electromechanical actuators and motors have limited ability to dissipate heat generated. Compactness, Light Weight, and Flexibility Fluid power cylinders and motors are relatively small and light weight. Flexible hoses allow compact packaging. Stiffness Hydraulic drives are stiff with respect to load disturbances; stiffness is the slope of the speed torque (force) curve. Control gains required in a high-power hydraulic control system would be significantly less than the gains required in a comparable electromagnetic control system. Fluid Power Systems & Control K. Craig 31

32 Fluid Power System Disadvantages Electric power is more readily available, cleaner and quieter, and easier to transmit. Hydraulic systems require pumps. Oil leakage, flammability, and fluid contamination Fluid cavitation and entrained air Challenging physics leads to more difficult modeling and control Fluid Power System Challenges Increase Efficiency Compact Energy Storage and Compact Power Sources Noise, Vibration, Leakage, Safety, and Ease of Use Create Portable, Untethered, Human-Scale Applications Fluid Power Systems & Control K. Craig 32