What is Control? Getting the System to do What you Want
Slide 3
How to Control? Add a Feedback Loop Pros: Eliminates errors
Disturbance rejection Cons: Stability? Sensors
Slide 4
Lets go back to simple control Todays topic: How to design the
command generator Pros: Simple, no sensors Stable (if plant is
stable) Accurate model not needed Cons: No disturbance rejection
Increase rise time
Slide 5
Before we go on A General Control System
Slide 6
Bridge Crane Vibration Problem
Slide 7
(and solution)
Slide 8
Why is Vibration Cancelled?
Slide 9
Derivation for a Simple Case Constraints Vibration Amplitude
(At the end of n impulses) Normalization Positive Impulses Time
Optimality
Input Shaping Arbitrary Commands Slight increase in rise time A
i = 1 so that shaped and initial commands have same steady state
From previous example: Zero-Vibration (ZV) shaper
Slide 12
Bridge Crane Vibration Problem
Slide 13
Typical Responses
Slide 14
Implementing a Digital Input Shaper Unshaped Command Shaped
Command
Slide 15
Shaper Robustness Insensitivity the width of a sensitivity
curve where vibration remains under V tol, the tolerable level of
vibration
Slide 16
Increasing Shaper Robustness Insensitivity the width of a
sensitivity curve where vibration remains under V tol, the
tolerable level of vibration
Slide 17
Increasing Shaper Robustness Extra Insensitive (EI) Shaper
Insensitivity the width of a sensitivity curve where vibration
remains under V tol, the tolerable level of vibration
Slide 18
Increasing Shaper Robustness Like a Boss Tradeoff: More
impulses are needed, and therefore slower rise time.
Slide 19
Multi-Mode Input Shaping Design a shaper for each mode, then
convolve to get a shaper that eliminates both modes
Slide 20
ZV Shaper for 1 Hz ZV Shaper for 2 Hz X ZV Shaper for 1 Hz and
2 Hz
Slide 21
Multi-Mode Specified Insensitivity (SI) Shaper
Slide 22
Shaping for Double-Pendulum Payloads
Slide 23
Shapers with Negative Impulses Unity Magnitude UMZV shaper
Negative shapers: Faster But less robust May excite un- modeled
higher modes
Slide 24
Special Case: Negative Shapers for On-Off Actuators Not On/Off
UMZV Shaper: On-Off
Slide 25
On-Off Thrusters: Flexible Satellites (Tokyo Institute of
Technology)
Slide 26
On-Off Thrusters: Flexible Satellites (Tokyo Institute of
Technology)
Slide 27
Input Shaping With Feedback Control Input Shaper * Cascaded set
of 2 nd order systems Collapse the feedback loop
Slide 28
Input Shaping and Feedback Control: Experimental Data
Disturbance at EndDisturbance During Motion
Slide 29
Input Shaping Inside the Feedback Loop: Hand-Motion Crane
Control
Slide 30
RF Hand-Motion Crane Control
Slide 31
Human Operator Studies
Slide 32
Human Operator Learning
Slide 33
UnshapedShaped
Slide 34
Portable Tower Crane 2mx2mx340 o Interfaces: Pendent, GUI,
Internet GUI Overhead Camera Used by Researchers and Students in
Atlanta, Japan, Korea
Slide 35
Tower Crane: System Overview Screen Interface
Slide 36
ME6404 Class Contest
Slide 37
Other Applications Many types of cranes Milling machines
Coordinate measuring machines Disk drives Long reach robots
Spacecraft
Slide 38
Scale of Micro Meters (10 -6 m) High Spindle Speeds (120 kRPM)
Application of Command Shaping to Micro Mills
Slide 39
Experimental Results Stage Tracking Error Part Surface
Slide 40
Coordinate Measuring Machines
Slide 41
Coordinate Measuring Machine (CMM) Deflection
Slide 42
Disk Drive Head Tester
Slide 43
Painting Robot
Slide 44
GRYPHON Mine Detecting Robot
Slide 45
Slide 46
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
Conclusions
