Transcript Slide 1

E- 579
Mechatronics Modeling and Simulation
Term Project - “ Steer By Wire”
Instructor
Dr. Shuvra Das
Divesh Mittal
Contents
• Introduction
•
•
•
•
•
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System level modeling
Bond graph model
SBW control
Results and Discussion
Limitations and Future work
References
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Introduction and Significance
• By wire system is getting popular because of its
efficient and accurate operations.
• There are still few concerns and issues.
• Idea here is to model simple steer by wire system and
see if we can replicate the results from existing
hydraulic steering system.
• This is simple model to understand, idea needs to be
extended in order to get more close to real world.
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Problem Definition
• Understand and prepare system level model of Steer
By Wire (SBW) system.
• Making the suitable assumptions to break down
whole system into simple energy storage or
dissipating elements.
• Convert above information into bond graph model
and simulate it on 20-SimTM.
• Plot wheel angle and validate it with similar results
from other references.
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Steer By Wire System
[“Embedded Steer-by-Wire System Development”, Embedded World, 17-19 February 2004,
Nuremberg, Germany]
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Steer by Wire
Reference: http://www.Howstuffworks.com
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• Introduction
• System level modeling
•
•
•
•
•
Bond graph model
SBW control
Results and Discussion
Limitations and Future work
References
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System Level Model
SBW
Steering Wheel
Subsystem
Steering Wheel
Motor
Torque Sensor
Steering Angle
Sensor
Controller
Subsystem
Control Unit
•Reactive torque
•Control Path
Steering
Actuator (Motor)
Rack / Pinion
Gear
Tie rod
Steering Column
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Front Wheel
Subsystem
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Tire-Wheel
subsystem
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Modeling of SBW
• SBW system is composed of steering subsystem, controller
and tire subsystem.
• Model subsystems with the help of major components.
• Each component is a combination of capacitive/inertia/resistor
elements and is connected to other components with either a
transformer / gyrator elements or series / parallel junction.
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Block Diagram
Torque
Input
Control
Unit
DC
Motor
Rack /pinion
gear
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Tire/wheel
assembly
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• Introduction
• System level modeling
• Bond graph model
•
•
•
•
SBW control
Results and Discussion
Limitations and Future work
References
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Manual Rack and pinion steering
system
I
I
SteeringWheelInertia
MSe
Constant3
MSe2
1
OneJunction1
I
MassofRack
0
ZeroJunction1
1
OneJunction2
TF
TireInertia
1
0
TF
1
MSe
RackPinionGearratio OneJunction3 ZeroJunction2 SteeringArmRatio OneJunction5SelfAligningTorque Constant1
R
1
TieRodResistance OneJunction4
R
C

Steeringwheelresistance
SteeringColumnStiffness
Integrate1
C
TieRodStiffness
Steering
wheel/
column
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Constant4
Rack and pinion / tire
assembly
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Without feedback/No control
I
I
R
Front wheel
actuator motor
R
MotorShaftInertia
ArmatureInductanceArmatureResistance
C
MotorShaftResistance
MotorShaftStiffness
Constant2
MSe
1
FrontWheelMotorVoltage
GY
1
OneJunction6 MotorConstant OneJunction7
I
OneJunction1
I
GearMotorShaft
1
Se1
ZeroJunction3
TF
SteeringWheelInertia
Se
Rack/Pinion, tie rod
and tire asembly
0
0
1
ZeroJunction1
OneJunction2
I
MassofRack
TF
1
TireInertia
0
TF
1
MSe
RackPinionGearratio OneJunction3 ZeroJunction2 SteeringArmRatio OneJunction5SelfAligningTorque Constant1
R
1
TieRodResistance OneJunction4
R
C
Steeringwheelresistance
SteeringColumnStiffness
C
Steering wheel
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TieRodStiffness
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Data[3]
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Front wheel angle
Front Wheel Angle ( Without Feedback)
70
steeringwheelangle
frontwheelangle
60
50
40
30
20
10
0
-10
-20
-30
0
1
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2
3
4
5
6
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Wire system
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8
9
15
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Validation
Result from reference [1]
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Front wheel angle Vs steering wheel
angle
Front Wheel Angle vs Steering angle( Without Feedback)
frontwheelangle
3
1.70
2
1
0
400
-1
0
5
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15
20
25
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40
45
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Steering subsystem
I
I
R
R
MotorShaftInertia
ArmatureInductanceArmatureResistance
C
MotorShaftResistance
Motorshaftcomplaince
Constant2
MSe
1
Steeringwheelmotor
GY
1
OneJunction6MotorConstant
OneJunction7
0
ZeroJunction3
I
SteeringWheelInertia
Se
Se1
1
OneJunction1
R
0
ZeroJunction1
TF
GearMotorShaft
C
Steeringwheelresistance
SteeringColumnStiffness
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• Introduction
• System level modeling
• Bond graph model
• SBW control
• Results and Discussion
• Limitations and Future work
• References
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SBW Controller
• Steering wheel Motor Controller
• Front wheel actuator motor controller
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Controller
SBW controller [3]
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Steering Motor Controller
• Generates reactive torque.
• Easy to drive at low speed and vice versa.
• Reactive torque is function of velocity
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Gain factor for Steering control
Gain for steering motor actuator [3]
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Feed forward control
Bicycle model for steering behavior [3]
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Steering Torque Controller
I
I
R
R
MotorShaftInertia
ArmatureInductanceArmatureResistance
C
MotorShaftResistance
Motorshaftcomplaince
Constant2
MSe
1
Steeringwheelmotor
GY
1
OneJunction6MotorConstant
OneJunction7
0
ZeroJunction3
I
SteeringWheelInertia
drivertorque
MSe
MSe2
1
0
OneJunction1
ZeroJunction1
TF
GearMotorShaft
reactiontorque
R
C
velocity
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drivertorqueinput
Steeringwheelresistance
SteeringColumnStiffness
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Reaction Torque Control
Reaction Torque Control
Extratorque
Velocity {m/s}
Driver Torque input {N.m}
Reaction Torque
300
200
100
0
-100
0
1
2
3
4
5
6
7
8
9
10
time {s}
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•
•
•
•
Introduction
System level modeling
Bond graph model
SBW control
• Results and Discussion
• Limitations and Future work
• References
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Results
• Steer by wire was modeled using bond graph
technology.
• Controller for SBW improves maneuverability
and handling.
• Reactive torque can be controlled using torque
control mechanism.
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Proposed Time line VS Achievement Mapping
Proposed date
Task
Status
March 13
Topic search
Achieved at time
March 20
Background research
Achieved at time
March 27
Understanding the system
Achieved at time
March 29
Proposal Presentation
Achieved at time
April 02
Basic bond graph modeling
Achieved at time
April 04
Decide on modeling complexity of
sensors
Achieved at time
April 09
Modeling of controller
Started at time but
finished on April 15
April 11
Validation of results
Achieved at time
April 17
Final presentation
Achieved at time
April 21
Final report
Should be done in time.
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•
•
•
•
•
Introduction
System level modeling
Bond graph model
SBW control
Results and Discussion
• Limitations and Future work
• References
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Limitations and Future Work
• Torque control mapping for steering motor.
• Front wheel motor voltage control.
• Importing Matlab file for lookup tables.
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References
1. Srihari Vijaykumar ,”Analysis of an electric power
assisted steering system using bond graphs”, SAE
paper 2003-01-0586.
2. Srihari Vijaykumar ,” Application of bond graph
technique to the design of passenger car steering
system”, SAE paper 2002-01-0617.
3. Se-Wook Oh,” The development of an advanced
control method for the steer-by-wire system to
improve the vehicle maneuverability and stability”,
SAE paper 2003-01-0578
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Questions ??
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