Overview
Issues with Control Systems Courses Fear of too much math Lack of accessible hands on learning Teaching techniques antiquated
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Proposed Class Real World Design
Required task Required performance Budget
Real World (Pre-existing) Tools CAD Control/Simulation Software Hardware
Control System Low Cost Small Modifiable
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Quanser Control Solutions The Good
Accurate Well Designed Compatible with Matlab, Simulink and LabVIEW
The Bad Large Expensive Black Box Un-Modifiable
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Modifiable Control System(Lego NXT)
The Good Inexpensive (Commercial Product) Powerful Arm7 Processor Compatible with Matlab, Simulink and
LabVIEW Small Reconfigurable Open Source
The Bad Not as accurate as Quanser
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• Hardware design (MLCAD)
• Software tutorial• Sensor integration• Virtual Reality model
Design
• Dynamic model• Control theory• MATLAB• Simulink
Simulation• Construction• Programming• LEGO
MINDSTORMS NXT
Experimentation
Class Outline
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• Hardware design (Lego CAD)
• Itemized parts list• Virtual Reality Model
Design
• Dynamic model• Control theory• MATLAB• Simulink
Simulation• Construction• Programming (Simulink
– ECRobot) [1]• LEGO MINDSTORMS
NXT
Prototype and Experimentation
Class WILL Work If:
Pre-Existing Tools Exist Lego CAD ECRobot MATLAB/Simulink
Reconfigurable Platform Exits Lego NXT Kit
IF ANY DOES NOT EXIST WILL NOT WORK
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Case Study
Objective Make a two (2) wheeled balancing robot Minimum forward speed 0.1m/s Minimum turning speed π/4 rad/sec Minimum floor angle ±15o
10Segway [7]
Case Study: Simulation and Test
PID Balance Control Minimizes angular
pitch rate Gains manually tuned to
balance, peak between ±15º & 2 sec. settling time
Difficult to tune Moving average to
smooth calculation
120 2 4 6 8 10 12 14 16 18 20
-20
-15
-10
-5
0
5
10
15
20
Time [sec]
Pitc
h A
ngle
, θp [d
eg]
SimulationExperimental
Case Study: Simulation and Test
State Variable Feedback State feedback control using
linear quadratic regulator Weight matrices Q & R are
manually tuned Emphasis on wheel angle
and pitch angle
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0 2 4 6 8 10 12 14 16 18 20
-10
-5
0
5
10
Time [sec]
Pitc
h A
ngle
, θp [d
eg]
SimulationExperimental
Recap Class Designed to be
Fun Interactive Educational
Uses Pre-Existing Tools Lego NXT Lego CAD MATLAB/Simulink
Use Reconfigurable Small Low Cost Used for Multiple Design Problems
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References1. Yamamoto, Yorihisa: NXTway-GS Model-Based Design – Control of self-
balancing two-wheeled robot built with LEGO Mindstorm NXT. First Edition, 29 February 2008.
2. Nise, Norman S.: Control Systems Engineering Fourth Edition. John Wiley and Sons INC, 2004
3. Lofaro, Daniel M.: Control Design to Reduce the Effects of Torsional Resonance in Coupled Systems. Master’s Thesis, Drexel University Department of Electrical and Computer Engineering, May 2008.
4. Kwatny, Harry G. Blankenship Gilmer L. Nonlinear Control and Analytical Mechanics A Computational Approach. Birkhauser, Boston 2000.
5. Erkkinen, Tom: Embedded Coder Robot NXT Demo. Updated 18 December 2008 http://www.mathworks.com/matlabcentral/fileexchange/13399
6. Yamamoto, Yorihisa: NXTway-GS Model-Based Design – Control of self-balancing two-wheeled robot built with LEGO Mindstorm NXT. First Edition, 29 February 2008.
7. Le, Tony: NXT-WhIP: NXT Wheeled Inverted Pendulum. Master’s Thesis, Drexel University Department of Electrical and Computer Engineering, May 2008.
8. Greenwood, Donald T.: Principles Of Dynamics Second Edition. Prentice Hall, Upper Saddle River, New Jersey 1988.
9. Le Tony, Oh Paul: IDETC Presentation: System Integration Case Study: NXT-WhIP NXT Wheeled Inverted Pendulum. New York City, NY, 2008-04-08.
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Motor Controller Motor Controller
Friction Compensator Rotation, kδ’
Wheel sync, ksync
Motor velocity, kϕ’
Worked to balance, rotate, and keep wheels synchronized
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Motor Model Motors represented as rigid body Electrical & mechanical constants determined by
Hurbain & Watanabe trusted and validated
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