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Motion Control: Generating Intelligent Commands for Mechatronic Devices

Motion Control: Generating Intelligent Commands for Mechatronic Devices. Kelvin Peng January 31 st 2013. What is Control?. Getting the System to do What you Want. How to Control ?. Controls 101: Add a Feedback Loop!. Pros: Eliminates errors Disturbance rejection. Cons: Stability?

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Motion Control: Generating Intelligent Commands for Mechatronic Devices

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  1. Motion Control: Generating Intelligent Commands for Mechatronic Devices Kelvin Peng January 31st 2013

  2. What is Control? Getting the System to do What you Want

  3. How to Control? Controls 101: Add a Feedback Loop! • Pros: • Eliminates errors • Disturbance rejection • Cons: • Stability? • Sensors

  4. Let’s go back to simple control • Pros: • Simple, no sensors • Stable (if plant is stable) • Accurate model not needed • Cons: • No disturbance rejection • Increase rise time Today’s topic: How to design the command generator for oscillatory plants

  5. Bridge Crane Vibration Problem

  6. Bridge Crane Vibration Problem (and solution)

  7. Why is Vibration Cancelled? t1 t2

  8. Normalization Positive Impulses Time Optimality Solving for the two impulses Vibration Amplitude (after n impulses) We want this to be zero, i.e. V=0 t1 t2

  9. Solving for the two Impulses 3 equations, 3 unknowns Zero-Vibration (ZV) input shaper

  10. Input Shaping Arbitrary Commands • Slight increase in rise time • ΣAi = 1 so that shaped and initial commands have same steady state

  11. Bridge Crane Vibration Problem

  12. Typical Responses

  13. Implementing a Digital Input Shaper Unshaped Command Shaped Command

  14. Shaper Robustness Insensitivity – the width of a sensitivity curve where vibration remains under Vtol , the tolerable level of vibration

  15. Increasing Shaper Robustness Insensitivity – the width of a sensitivity curve where vibration remains under Vtol , the tolerable level of vibration

  16. Increasing Shaper Robustness Extra Insensitive (EI) Shaper Insensitivity – the width of a sensitivity curve where vibration remains under Vtol , the tolerable level of vibration

  17. Increasing Shaper Robustness Like a Boss Tradeoff: More impulses are needed, and therefore slower rise time.

  18. Multi-Mode Input Shaping Design a shaper for each mode, then convolve to get a shaper that eliminates both modes

  19. ZV Shaper for 1 Hz and 2 Hz ZV Shaper for 1 Hz X ZV Shaper for 2 Hz

  20. Multi-Mode Specified Insensitivity (SI) Shaper

  21. Shaping for Double-Pendulum Payloads

  22. Shapers with Negative Impulses • Negative shapers: • Faster • But less robust • May excite un-modeled higher modes Unity Magnitude UMZV shaper

  23. Special Case: Negative Shapers for On-Off Actuators UMZV Shaper: On-Off Not On/Off

  24. On-Off Thrusters: Flexible Satellites (Tokyo Institute of Technology)

  25. On-Off Thrusters: Flexible Satellites (Tokyo Institute of Technology)

  26. Input Shaping With Feedback Control Collapse the feedback loop Input Shaper * Cascaded set of 2nd order systems

  27. Disturbance During Motion Input Shaping and Feedback Control: Experimental Data Disturbance at End

  28. Input Shaping Inside the Feedback Loop: Hand-Motion Crane Control

  29. RF Hand-Motion Crane Control

  30. Human Operator Studies

  31. Human Operator Learning

  32. Human Operator Learning Unshaped Shaped

  33. Portable Tower Crane • 2mx2mx340o • Interfaces: Pendent, GUI, Internet GUI • Overhead Camera • Used by Researchers and Students in Atlanta, Japan, Korea

  34. Screen Interface Tower Crane: System Overview

  35. ME6404 Class Contest

  36. Other Applications • Many types of cranes • Milling machines • Coordinate measuring machines • Disk drives • Long reach robots • Spacecraft

  37. Multi-Hoist Cranes

  38. Multi-Axis Input Shaping

  39. Application of Command Shaping to Micro Mills • Scale of Micro Meters (10-6m) • High Spindle Speeds (120 kRPM)

  40. Part Surface Experimental Results Stage Tracking Error

  41. Coordinate Measuring Machines

  42. Coordinate Measuring Machine (CMM) Deflection

  43. Disk Drive Head Tester

  44. Painting Robot

  45. GRYPHON Mine Detecting Robot

  46. GRYPHON Mine Detecting Robot

  47. Conclusions • Every control method has strengths and weaknesses (Feedback is not a magic cure-all) • The command issued to a system has a significant influence on its response • Input shaping • Is excellent for applications with problematic vibrations • Is easy to implement

  48. Thank you

  49. Before we go on… A General Control System

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