Dynamic Traction Control

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Dynamic Traction Control

• By Thiago Avila, Mike Sinclair Jeffrey McLarty

2
Motivation

• Drastically improve vehicle performance and
  safety by maintaining optimal wheel traction in
  all road conditions

3
Motivation
4
Needs Assessment

• FSAE car is currently traction limited and would
  benefit from the use of a traction control system
• System must follow FSAE guidelines
• Minimal cost solution should be pursued

5
Design Criteria and Constraints

• Meet FSAE Guidelines
• Predict slip with enough time to adjust engine
  output
• Reduced FSAE 75m acceleration times
• Improve FSAE skid pad testing results

6
Problem Formulation

• The traction control system is required to
  prevent driver error from overloading any of the
  four wheels and causing slip, through either
  throttle or brake application

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Abstraction

• Physics model sensors
• 3-axis Accelerometer
• Linear Potentiometer Cost Complexity
• Engine Power Control
• Cutting Spark Difficult to Predict Power
• Limiting Fuel Improper Fuel Ratio
• Drive by wire throttle Infringes FSAE rules
• Electronic Air Restrictor

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Proposed Solution Breakdown

• Slip Model
• Vehicle Dynamics and Sensing
• Vehicle Control
• Electronic Restrictor

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Proposed Solution

• Slip Model
• Dynamic Physics Model
• Dynamic Coefficient of Friction
• Understeer Detection

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Design Layout
Slip Angle Radius
External Sensors
X/Y/Z Acceleration
-
CBR 600 F4i Engine
Physics Model (Saturator)
Driver Pedal

Wheels

RPM Throttle Pos.
µs/µk
Wheel Slip Detector
ECU
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Physics Model
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Torque Map
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Interpolation
Engine Speed

• Interpolate Between Four Points on Torque Map
• Interpolate between Engine Speeds at Throttle 1

Throttle
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Interpolation
Engine Speed

• Interpolate Between Four Points on Torque Map
• Interpolate between Engine Speeds at Throttle 1
• Interpolate between Engine Speeds at Throttle 2

Throttle
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Interpolation
Engine Speed

• Interpolate Between Four Points on the Torque Map
• Interpolate between Engine Speeds at Throttle 1
• Interpolate between Engine Speeds at Throttle 2
• Interpolate between results at different
  Throttles

Throttle
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Interpolation
Engine Speed

• Interpolate Between Four Points on the Torque Map
• Interpolate between Engine Speeds at Throttle 1
• Interpolate between Engine Speeds at Throttle 2
• Interpolate between results at different
  Throttles

Throttle
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Interpolation
Engine Speed

• Interpolate Between Four Points on the Torque Map
• Interpolate between Engine Speeds at Throttle 1
• Interpolate between Engine Speeds at Throttle 2
• Interpolate between results at different
  Throttles
• Engine Power from 4 point Interpolation Done

Throttle
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Physics Model
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Data Acquisition

• Installed Sensors
• Steering Wheel Angle
• 2-D Acceleration
• Suspension Deflection
• Wheel Velocity
• Brake Pressure
• Engine RPM
• Throttle Position
• Air Mass Flow Rate

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Physics Model Simulation
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Model Validation FL Tire
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Slip Condition
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Dynamic Coefficient of Friction Calculator
Slip Detected
Calculate Engine Torque _at_ T(0)
Calculate Vertical Force _at_ T(0)
Calculate Coefficient of Friction and Update
Model µs
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Optimize Performance
No Slip Detected Is µs at the limit?
Maintain current µs
Increase µs
Yes
No
Initial Value
New Limit
Calculated Values
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Understeer Detection

• Turning Radius
• Desired vs. Actual
• Major Factor
• Wheel Slip Angle

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Slip Angle
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Proposed Solution

• Vehicle Control
• Electronic Restrictor
• Brake Pressure Controller

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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
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Electronic Restrictor
Rotary Potentiometer
Servo
Gears
Butter -Fly- Valve
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Electronic Restrictor
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Patents
Slip Angle Radius
External Sensors
X/Y/Z Acceleration
-
CBR 600 F4i Engine
Physics Model (Saturator)
Driver Pedal

Wheels

RPM Throttle Pos.
µs/µk
Wheel Slip Detector
ECU
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Patents
Slip Angle Radius
External Sensors
X/Y/Z Acceleration
-
CBR 600 F4i Engine
Physics Model (Saturator)
Driver Pedal

Wheels

RPM Throttle Pos.
µs/µk
Wheel Slip Detector
ECU
Possibly patentable Continuously Improving
Predictive Traction Control
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Commissioning
Start
Order Parts Materials
Program PSoC with Physics Model Interpolation
1 day
3.5 weeks
Finish
Install Restrictor
Build Restrictor
2 weeks
1 week
Test Optimize
Create Controller based on Design Criterion
4 weeks
2.5 weeks
Critical Path 10 weeks

• The Plan

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Questions?

• Comments?

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The End

• Thank you!