Active Suspension System Test Platform

1
Active Suspension System Test Platform Controls
Senior Presentation
Project Member Jerry L. Campbell
Advisor Mr. Steven Gutschlag
Presented 29 April 2004
2
Outline

1. Project Overview
2. Functional Description
3. System Block Diagram
4. System Identification
5. Plant Model
6. System Performance
7. Problems Encountered
8. Future Work
9. Questions

3
Overview
Reliable Test Platform Digital Controller for DC
Actuator Used by Future Bradley University
Projects
4
System
Inputs Outputs
Desired Platform Motion (R) Actual Platform Motion (C)
Note Desired system response is
CR, or C/R 1.0 EMAC Micropac 535
micro-controller based development board
(Controller)
Inputs Outputs
Keypad (Desired Platform Motion) Actuator Drive Signal
Max. Platform Motion Amplitude LCD Display
Actuator (plant)
Inputs Outputs
Error Signal from Controller Platform Movement
Position Signal
Disturbance Force (Load)
5
Modes of Operation

• Sinusoidal
• Step
• Triangular

Note Step and Triangle functions can be single
or continuous
6
Software Initialization Flow Chart
7
Basic System Block Diagram Shown in a General
Configuration
Input
Digital Controller
Actuator
Platform Motion
Plant
EMAC MicroPac 535 Development System
Input Voltage Signal Representing the Desired
Platform Motion ( Provided by the
Micro-Controller )
8
System Identification
Detailed Spec Sheet Not Available Need Accurate
Mathematical Model Obtained Via Frequency
Response and Load vs. Speed Measurements
9
Block Diagram of a Simple DC Machine ( Open Loop)
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Sample Frequency Response Data Sample
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Frequency Response
17
16
15
Red gt Slope from pencil Line
Bluegt Slope from Cursors
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Actuator Velocity dB
13
12
11
10
0
1
2
10
10
10
Applied Frequency w
12
Frequency Response
20
18
-3dB point at 42 rad/sec
16
14
12
Actuator Velocity dB
10
Red gt Slope from pencil Line
Bluegt Slope from Cursors
8
6
4
2
0
0
1
2
3
10
10
10
10
Applied Frequency w
13
Phase (peak to inflection) VS. Frequency
0
-10
-20
-30
-40
Phase (degrees)
-50
-60
-70
-80
-90
-100
0
1
2
28
10
10
10
Applied Frequency (rad/sec)
14
Preliminary Simulink Model for the Warner Linear
Actuator Including Non-Linear Effects
15
Backlash Effects
Position
Input
16
Simplified Model Assumptions
System is Linear Backlash Not Present Dead Band
Not Present
17
Force (load)
Position
System Model
Va
Simplified System Model
18
Simplified System Simulink Model
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PM Determination
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Phase Margin Determination
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System Performance
Position With Controller
Position Without Controller
Lower Actuator Position Limit
22
Simplified System Simulink Model
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System Performance
Input
K 10
K 20
K 40
K 80
Note Backlash Effects Minimized as Gain
Increases
24
System Step Response
Input
K 40
Position
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Other Controller Options and Obstacles

• Integrator
• PI Controller

26
Problems Encountered
Current Limiting Caused Inadequate Data Time
Required for System Identification Insufficient
Time Left to Implement Digital Control
27
Future Work
Select Practical Hardware Micro-Controller
Code Implement Digital Controller W/
EMAC Construct Test Platform
28
Questions
29
Questions
30
Questions
31
Lumped Parameter Model
32
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