: New technologies in feedback devices - Reduce costs and improve performance, maintenance, and efficiency

Transcription

1 : New technologies in feedback devices - Reduce costs and improve performance, maintenance, and efficiency Joanna Suresh, Product Manager, SICK, Inc.

2 Agenda : Introduction : Selection of encoders - The basics Mechanical fit Electrical configuration : Motor feedback encoders - Background - Evolution of motor feedback systems - Common interfaces used in the past - Digital interfaces comparison : Key market drivers : Industry trends Cost reduction Machine safety Changing technology Energy efficient systems

3 Selection of feedback devices : Basic parameters - Mechanical dimensions Housing size Shaft options Tapered Solid shaft - Operating speed

4 Selection of feedback devices : Electrical options (speed, position) Absolute (single and multi turn) Incremental Interface TTL/HTL SSI or fieldbus Drive communication (Hiperface, Endat, BiSS) Resolution Accuracy Speed stability Error limits

5 Factory floor 5

6 General areas of application High What precision and performance is required in motion control? Usually servos Medium Motor feedback encoders Functional differentiation Performance Low Is auxiliary axis control compatible with existing drive a requirement? Stepper motors DC motors AC motors Yes Absolute encoders Incremental encoders Safety Stand-alone motor feedback encoders

7 Evolution of Motor Feedback systems Past Present Position control Position control Analog Analog drive drive power power Digital Digital drive drive power power motor motor motor motor

8 Interfaces Past and present Digital + Analog EnDat 2.1 Pure Digital EnDat 2.2 BiSS B 8

9 HIPERFACE DSL vs. EnDat 2.2 EnDat 2.2 Technical specification of EnDat 2.2 9

10 HIPERFACE DSL vs. EnDat 2.2 EnDat 2.2 Interface circuit specification Interface circuit specification 2 Wire 4 Wire 10

11 HIPERFACE DSL vs. EnDat 2.2 vs. BiSS Hiperface DSL EnDat2.2 BiSS B supply voltage 10-30V 3,6V 5,25V bzw. 14V Max. cable length 100m 100m (only with 8MHz clock rate) 1200m necessary wires 2 wires 6 wires 6-8 wires clock rate 9,2 MHz 16 MHz 80kHz.. 10MHz (RS422) *) Registermode.. 250kHz Min. drive cycle 12,5µs 25µs 12,5.. 40µs delay of position calculation (jitter) 20ns <5 µs < 40µs **) down time 9µs 3,75 µs sensor and bitrate dependant signal propagation delay determination automatically manual (min. 3 times) manual safety concept up to SIL3 up to SIL2 - synchronicity Synch to drive cycle - - support of external sensors No protocol limit max. 16 max. 7 lifetime prediction yes yes No standard, mostly recommendations *) Requirement: small runtime in relation to clock rate **) manufacturer-/ device dependent 11

12 Key market drivers

13 General Market Trends : Cost Reduction - All costs not limited to design and development, parts, installation, maintenance, etc. : Machine Safety Standards - With more emphasis on safety in the US, and changing standards in Europe, safety in drive systems is gaining importance : Changing Technology\Mechanics - There are many different mechanical and technological variations, it is in the best interest of the OEM to standardize on a solution that offers maximum flexibility. By standardizing on motor design, there are savings in design time, time to market and production costs : Customizations/Value Add - Modifications to standard off-the-shelf products are required for specialized applications : Environment - There is an advantage for feedback devices to function in rugged environments, without compromising precision and durability : Presentation Title 13

14 Cost savings Part reduction : Elimination of a cable connector (e.g., using Hiperface DSL) - The elimination of the motor feedback connector plug in the new design results in significant cost savings Source: Beckhoff : Consolidation of motor related sensory information - Ability to connect other motor sensors to a hub within the motor feedback system - No additional connection wires to drive

15 Reducing design and development time and costs : Simplification of development - Quick and simple implementation - the IP core for the leading FPGAs (Xilinx Spartan-3, Xilinx Spartan-6, Altera Cyclone-III ) is now made available by feedback device manufacturers - No royalties DSL Master: FPGA IP-core : Easy-to-use testing and implementation tools - Diagnostic tool - Link capability - Evaluation encoders

16 Cost reduction and higher productivity : Maintenance costs - Improved diagnostics and condition monitoring for scheduled maintenance increases productivity - Encoder usage history for root cause analysis - Lifetime prediction Amount < >120 : Installation - Easy to mount onto motors on the production line - Visual aids Temperature

17 Safety standards for drive-related functions Soft stop and soft axis controls will become more important Manufacturers will be looking for safety ratings from suppliers 17

18 Advantages of using a safety-rated feedback device : Benefits of integration safety encoders into drive systems: - Cost saving due to assembled functional groups - Easy certification of entire system due to use of certified components - Less downtime Selective ON /OFF switching - Cost savings due to the use of external monitoring and protection equipment 18

19 Safety functions of servo drives Safe stop and brake functions STO Safe torque off SS1 Safe stop 1 SOS Safe operating stop SS2 Safe stop 2 SBC Safe brake control Safe motion functions SLA Safely-limited acceleration SAR Safe acceleration range SLS Safely-limited speed SSR Safe speed range SLT Safely-limited torque STR Safe torque range SLP Safely-limited position SLI Safely-limited increment SDI Safe direction SCA Safe cam SSM Safe speed monitor

20 Safety failure modes : Considered failure modes - Mechanical failures of encoder Shaft attachment Housing attachment Loss of code disc - Electronical m2 failures of encoder Signal shape Static signals Shortcuts, open circuits - Transmission failures Loss, insertion, repetition of frames Data corruption - Electronical failures of drive interface Static signals Shortcuts, open circuits 20

21 Slide 20 m2 Should this just be Electronic? manortr, 2/14/2012

22 Changing technology : Feedback encoders are best when they are designed to be simple, yet versatile : For example, a technology platform that offers one mechanical interface with different electrical interfaces : The different series based on a single powerful technology are - Incremental encoders (HTL, TTL, Sin Cos), - Absolute encoders (SSI) - HIPERFACE interface : This benefits the customer by standardizing motor design, saving design time, time to market and production costs

23 Energy efficient systems : There is significant emphasis on creating lean and green systems in today s world. A direct drive system saves energy costs as transmission losses are almost nonexistent : A direct drive is a system whereby the motor (actuator) is mounted directly to the part to be moved (such as an endeffector), thereby eliminating transmission loses - Due to such a configuration, the speed of the motor and the machine are identical and no torque will be lost due to a gear box, lead screw, or any coupling element : New challenge - Finding an encoder to match the mounting configuration

24 Other trends : Customizations/Value Add - Modifications to standard off-the-shelf products are required for specialized applications - Value added services are very effective in differentiating from competition : Environment - There is an advantage for feedback devices to function in rugged environments, without compromising precision and durability Inductive technology Capacitive technology No bearings in the encoder, enable longer life

25 To summarize : Motor feedback encoders are an integral part of a closed loop control system and the reliability and performance of the feedback device is vital to successful motion control : Cost savings affecting parts, development, validation, testing and diagnostics are vital aspects to be considering when designing a motor feedback system : Safety, versatility, performance and easy maintenance are the desired attributes of any motion control system

26 : Thank you for your attention