Motion Control: Generating Intelligent Comands for Mechatronic Devices

1. Motion Control: Generating Intelligent Comands for Mechatronic Devices Kelvin Peng Feburary 7th 2012

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

3. How to Control? 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

5. Before we go on… A General Control System

6. Bridge Crane Vibration Problem

7. Bridge Crane Vibration Problem (and solution)

8. Why is Vibration Cancelled?

9. Normalization Positive Impulses Time Optimality Derivation for a Simple Case Constraints Vibration Amplitude (At the end of n impulses)

10. Simple Derivation (V=0, 2 impulses) 3 equations, 3 unknowns

11. Input Shaping Arbitrary Commands From previous example: Zero-Vibration (ZV) shaper • Slight increase in rise time • ΣAi = 1 so that shaped and initial commands have same steady state

12. Bridge Crane Vibration Problem

13. Typical Responses

14. Implementing a Digital Input Shaper Unshaped Command Shaped Command

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

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

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

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

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

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

21. Multi-Mode Specified Insensitivity (SI) Shaper

22. Shaping for Double-Pendulum Payloads

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

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

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

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

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

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

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

30. RF Hand-Motion Crane Control

31. Human Operator Studies

32. Human Operator Learning

33. Human Operator Learning Unshaped Shaped

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

35. Screen Interface Tower Crane: System Overview

36. ME6404 Class Contest

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

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

39. Part Surface Experimental Results Stage Tracking Error

40. Coordinate Measuring Machines

41. Coordinate Measuring Machine (CMM) Deflection

42. Disk Drive Head Tester

43. Painting Robot

44. GRYPHON Mine Detecting Robot

45. GRYPHON Mine Detecting Robot

46. 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 • Can dramatically reduce system vibration • Is easy to implement

47. Thank you