divesh mittal
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E- 579Mechatronics Modeling and Simulation
Term Project - “ Steer By Wire”
InstructorDr. Shuvra Das
Divesh Mittal
April 17, 2006 E-579 - Steer By Wire system 2
Contents
• Introduction• System level modeling
• Bond graph model
• SBW control
• Results and Discussion
• Limitations and Future work
• References
April 17, 2006 E-579 - Steer By Wire system 3
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.
April 17, 2006 E-579 - Steer By Wire system 4
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.
April 17, 2006 E-579 - Steer By Wire system 5
Steer By Wire System
[“Embedded Steer-by-Wire System Development”, Embedded World, 17-19 February 2004, Nuremberg, Germany]
April 17, 2006 E-579 - Steer By Wire system 6
Steer by Wire
Reference: http://www.Howstuffworks.com
April 17, 2006 E-579 - Steer By Wire system 7
• Introduction
• System level modeling• Bond graph model
• SBW control
• Results and Discussion
• Limitations and Future work
• References
April 17, 2006 E-579 - Steer By Wire system 8
System Level Model
SBW
Steering Wheel Subsystem
Controller Subsystem
Front Wheel Subsystem
Steering Wheel Motor
Torque Sensor
Steering Angle Sensor
Steering Actuator (Motor)
Rack / Pinion Gear
Tire-Wheel subsystem
Steering Column
Tie rod
Control Unit
•Reactive torque
•Control Path
April 17, 2006 E-579 - Steer By Wire system 9
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.
April 17, 2006 E-579 - Steer By Wire system 10
Block Diagram
Torque Input
Control Unit
DC Motor
Rack /pinion gear
Tire/wheel assembly
April 17, 2006 E-579 - Steer By Wire system 11
• Introduction
• System level modeling
• Bond graph model• SBW control
• Results and Discussion
• Limitations and Future work
• References
April 17, 2006 E-579 - Steer By Wire system 12
Manual Rack and pinion steering system
ISteeringWheelInertia
RSteeringwheelresistance
0ZeroJunction1
CSteeringColumnStiffness
1OneJunction2
TFRackPinionGearratio
1OneJunction3
IMassofRack
0ZeroJunction2
1OneJunction4
CTieRodStiffness
RTieRodResistance
TFSteeringArmRatio
1OneJunction5
ITireInertia
MSeSelfAligningTorque Constant1
Integrate1
Constant4
Constant3
MSeMSe2
1OneJunction1
Steering wheel/ column Rack and pinion / tire
assembly
April 17, 2006 E-579 - Steer By Wire system 13
Without feedback/No control
1OneJunction1
ISteeringWheelInertia
RSteeringwheelresistance
0ZeroJunction1
CSteeringColumnStiffness
1OneJunction2
TFRackPinionGearratio
1OneJunction3
IMassofRack
0ZeroJunction2
1OneJunction4
CTieRodStiffness
RTieRodResistance
TFSteeringArmRatio
1OneJunction5
ITireInertia
MSeSelfAligningTorque
MSeFrontWheelMotorVoltage
1OneJunction6
IArmatureInductance
RArmatureResistance
GYMotorConstant
1OneJunction7
IMotorShaftInertia
RMotorShaftResistance
0ZeroJunction3
CMotorShaftStiffness
TFGearMotorShaft
Constant1
Constant2
SeSe1
Front wheel actuator motor
Steering wheel
Rack/Pinion, tie rod and tire asembly
April 17, 2006 E-579 - Steer By Wire system 14
Data[3]
April 17, 2006 E-579 - Steer By Wire system 15
Front wheel angle
Front Wheel Angle ( Without Feedback)
0 1 2 3 4 5 6 7 8 9 10time {s}
-30
-20
-10
0
10
20
30
40
50
60
70
steeringwheelanglefrontwheelangle
April 17, 2006 E-579 - Steer By Wire system 16
Validation
Result from reference [1]
April 17, 2006 E-579 - Steer By Wire system 17
Front wheel angle Vs steering wheel angle
Front Wheel Angle vs Steering angle( Without Feedback)
0 5 10 15 20 25 30 35 40 45steeringwheelangle
-1
0
1
2
3
frontwheelangle
1.70
400
April 17, 2006 E-579 - Steer By Wire system 18
Steering subsystem
1OneJunction1
ISteeringWheelInertia
RSteeringwheelresistance
0ZeroJunction1
CSteeringColumnStiffness
MSeSteeringwheelmotor
1OneJunction6
IArmatureInductance
RArmatureResistance
GYMotorConstant
1OneJunction7
IMotorShaftInertia
RMotorShaftResistance
0ZeroJunction3
TFGearMotorShaft
Constant2
SeSe1
CMotorshaftcomplaince
April 17, 2006 E-579 - Steer By Wire system 19
• Introduction
• System level modeling
• Bond graph model
• SBW control• Results and Discussion
• Limitations and Future work
• References
April 17, 2006 E-579 - Steer By Wire system 20
SBW Controller
• Steering wheel Motor Controller
• Front wheel actuator motor controller
April 17, 2006 E-579 - Steer By Wire system 21
Controller
SBW controller [3]
April 17, 2006 E-579 - Steer By Wire system 22
Steering Motor Controller
• Generates reactive torque.
• Easy to drive at low speed and vice versa.
• Reactive torque is function of velocity
April 17, 2006 E-579 - Steer By Wire system 23
Gain factor for Steering control
Gain for steering motor actuator [3]
April 17, 2006 E-579 - Steer By Wire system 24
Feed forward control
Bicycle model for steering behavior [3]
April 17, 2006 E-579 - Steer By Wire system 25
Steering Torque Controller
1OneJunction1
ISteeringWheelInertia
RSteeringwheelresistance
0ZeroJunction1
CSteeringColumnStiffness
MSeSteeringwheelmotor
1OneJunction6
IArmatureInductance
RArmatureResistance
GYMotorConstant
1OneJunction7
IMotorShaftInertia
RMotorShaftResistance
0ZeroJunction3
TFGearMotorShaft
Constant2
CMotorshaftcomplaince
drivertorqueinput
reactiontorque
velocity
drivertorqueMSeMSe2
April 17, 2006 E-579 - Steer By Wire system 26
Reaction Torque Control
Reaction Torque Control
0 1 2 3 4 5 6 7 8 9 10time {s}
-100
0
100
200
300
ExtratorqueVelocity {m/s}Driver Torque input {N.m}Reaction Torque
April 17, 2006 E-579 - Steer By Wire system 27
• Introduction
• System level modeling
• Bond graph model
• SBW control
• Results and Discussion• Limitations and Future work
• References
April 17, 2006 E-579 - Steer By Wire system 28
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.
April 17, 2006 E-579 - Steer By Wire system 29
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.
April 17, 2006 E-579 - Steer By Wire system 30
• Introduction
• System level modeling
• Bond graph model
• SBW control
• Results and Discussion
• Limitations and Future work• References
April 17, 2006 E-579 - Steer By Wire system 31
Limitations and Future Work
• Torque control mapping for steering motor.
• Front wheel motor voltage control.
• Importing Matlab file for lookup tables.
April 17, 2006 E-579 - Steer By Wire system 32
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
April 17, 2006 E-579 - Steer By Wire system 33
Questions ??
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