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E597 Steering System Input Servo Modeling

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Take steering response data from steering servo disconnected from ... Ix armature = 452mkg-m^2 (calculated) Coil R = 0.4 ohm (measured) Coil I = 70uH (measured) ... – PowerPoint PPT presentation

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Title: E597 Steering System Input Servo Modeling


1
E597 Steering System Input Servo Modeling
Vehicle Validation
  • by Jerome Ivan

2
Summary
  • Project goals
  • Vehicle Data
  • Servo description
  • Steering servo model
  • Potential reasons for inaccurate emulation
  • Things gone wrong
  • Things that could have been done better
  • Will I continue?
  • Schedule shortfalls
  • Analysis Tools

3
Project Goals
  • Take steering response data from steering servo
    disconnected from vehicle
  • Take steering response data from vehicle as a
    function of speed steering servo connected
  • Develop and validate steering servo model using
    test data bond graph model
  • Use data from the vehicle to derive lump sum
    steering system C, I and R using the bond graph
    model

4
Steering Freewheeling Kd 1000 /- 10deg.
5
Steering Freewheeling Kd 0 /- 10deg.
6
Steering Freewheeling / No Steering Wheel Kd
1000 /- 90deg.
7
Steering Freewheeling / No Steering Wheel Kd 0
/- 90deg.
8
Steering Vehicle 0 MPH Kd 1000 /- 90deg.
9
Steering Vehicle 10 MPH Kd 1000 /- 90deg.
10
Servo System Description
  • Steering Servo System

11
Servo System Description
  • Motor Chain Drive

12
Servo System Measurements (no motor data)
  • Ix armature 452mkg-m2 (calculated)
  • Coil R 0.4 ohm (measured)
  • Coil I 70uH (measured)
  • Steering Shaft K 100Nm/rad (measured)
  • Bearing R 0.05Nms/rad (estimated)
  • Motor produces 2.5N _at_ 54amps
  • Motor K .0463Nm/A (calculated)

13
Servo System Measurements (no motor
data)Homemade Motor Curve
14
Steering Servo Model
  • Simulink Controller

15
Steering Servo Model Bond Graph
16
20-Sim Servo SimulationFails to emulate ringing.
17
Possible Reasons for Inaccurate Emulations
  • 20-Sim PD Controller was an invalid
    representation of the Simulink controller.
  • Inaccurate bond graph parameters
  • Bandwidth limitations of actual controller not
    found in simulation.
  • Bond graph model has infinite current source /
    vehicle had a 30 duty cycle limit or about a
    20Amp limit.

18
Possible Reasons for Inaccurate Emulations
  • Bandwidth of actual controller

19
Possible Reasons for Inaccurate Emulations
  • Bandwidth of simulation controller

20
Things Gone Wrong
  • I was never able to accurately emulate steering
    controller.
  • I Could not complete the task of deriving
    lump-sum I, C R for the steering system.
  • Not enough time to run the HP Signal Analyzer in
    vehicle (bode plots.)
  • No motor data

21
Things That Could Have Been Better
  • I Could have shut off Simulink steering
    controller and taken open-loop data in vehicle.
  • Used open-loop data to validate bond graph model
    without PD controller.
  • I Could have attempted to build a more
    representative discrete controller in 20-Sim

22
Will I continue to use the Bond Graph Method?
  • Yes, the bond graph method works well for driving
    the state space equations.
  • Everyone in the department uses Simulink and is
    at the mercy of SAE documentation for developing
    models.

23
Schedule Short Falls
  • Week 1- (Mar 27-31) run test stand build servo
    bond graph
  • Week 2- Validate servo model take data in
    vehicle (could not validate servo model)
  • Week 3- Validate lump sum vehicle model finish
    PPT (without accurate servo model, there was no
    sense in trying to infer lump sum steering system
    I, C R.

24
Analysis Tools
  • 20-sim
  • MathWorks Simulink
  • MatLab
  • HP Full Bridge Tester
  • Norton, R. L, Machine Design An Integrated
    Approach, Prentice-Hall Inc.,1998

25
FIN
  • Ford F-250 Roaming Robot NQE
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