Dynamic Traction Control By Thiago Avila Mike Sinclair

Dynamic Traction Control By: Thiago Avila, Mike Sinclair & Jeffrey Mc. Larty

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

10. 000 Acceleration [m/s 2] 5. 000 0 1 2 3 4 5 6 7 8 of Gravity 9 Centre Front Tire Rear Right Tire -5. 000 Rear Left Tire -10. 000 -15. 000 Motivation Time [s]

�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 Needs Assessment

◦ Meet FSAE Guidelines ◦ Predict slip with enough time to adjust engine output ◦ Reduced FSAE 75 m acceleration times ◦ Improve FSAE skid pad testing results Design Criteria and Constraints

�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 Problem Formulation

�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 Abstraction

�Slip Model ◦ Vehicle Dynamics and Sensing �Vehicle Control ◦ Electronic Restrictor Proposed Solution Breakdown

�Slip Model ◦ Dynamic Physics Model ◦ Dynamic Coefficient of Friction ◦ Understeer Detection Proposed Solution

External Sensors Slip Angle Radius X/Y/Z Acceleration Driver Pedal + Physics Model (Saturator) RPM Throttle Pos. ECU μs/μk Wheel Slip Detector Design Layout CBR 600 F 4 i Engine Wheels

Physics Model

14 00 0 13 00 5 13 00 0 12 00 5 12 00 0 11 00 5 11 00 0 10 00 5 10 00 0 95 00 90 00 85 00 80 00 75 00 70 00 65 00 60 00 55 00 50 00 45 00 40 00 35 00 30 00 25 00 20 10 0 Torque (N-m) 60 50 40 30 Engine Speed (RPM) -10 Torque Map

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

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

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 Interpolation

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 Interpolation

Physics Model

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

800 700 Normal Force (N) 600 500 Rear Left 400 Rear Right FL Model Front Right 300 200 100 0 0 25 50 75 100 125 150 175 200 Time 225 250 275 300 325 Physics Model Simulation 350 375 400

600 Vertical Force (N) 500 400 300 Modeled Vertical Force Spring Force 200 100 0 0 25 50 75 100 125 150 175 200 Time 225 250 275 300 325 Model Validation – FL Tire 350 375 400

10. 000 Acceleration [m/s 2] 5. 000 0 1 2 3 4 5 6 7 Centre of Gravity 8 9 Front Tire Rear Right Tire -5. 000 Rear Left Tire -10. 000 Slip [True/False] -15. 000 Time [s] 1 Slip 0 0 -1 1 2 3 4 5 Time [s] Slip Condition 6 7 8 9

Calculate Engine Torque @ T(0) Slip Detected Calculate Vertical Force @ T(0) Calculate Coefficient of Friction and Update Model μs Dynamic Coefficient of Friction Calculator

Yes Maintain current μs No No Slip Detected Increase μs Is μs at the limit? 1. 4 Initial Value Coefficient of Friction 1. 3 1. 2 New Limit 1. 1 1 0. 9 0. 8 0. 7 Calculated Values 0. 6 0. 5 0 20 40 60 Time 80 100 Optimize Performance 120 140

�Turning Radius: ◦ Desired vs. Actual �Major Factor: ◦ Wheel Slip Angle Understeer Detection

1000 Lateral Force vs. Slip Angle 800 600 400 Lateral Force (lbf) 200 Goodyear 7, 12 psi, IA 0, load 50 Goodyear 7, 12 psi, IA 0, load 150 0 -15 -10 -5 0 -200 Goodyear 7, 12 psi, IA 0, load 250 10 15 Goodyear 7, 12 psi, IA 0, load 350 Goodyear 7, 12 psi, IA 0, load 450 -400 -600 -800 -1000 Slip Angle [degrees] Slip Angle 5

�Vehicle Control ◦ Electronic Restrictor ◦ Brake Pressure Controller Proposed Solution

Electronic Restrictor

Rotary Potentiometer Servo Gears Butter -Fly. Valve Electronic Restrictor

Electronic Restrictor

External Sensors Slip Angle Radius X/Y/Z Acceleration Driver Pedal Physics Model (Saturator) RPM Throttle Pos. ECU Patents μs/μk + Wheel Slip Detector CBR 600 F 4 i Engine Wheels

External Sensors Slip Angle Radius X/Y/Z Acceleration Driver Pedal Physics Model (Saturator) RPM Throttle Pos. ECU μs/μk + CBR 600 F 4 i Engine Wheels Wheel Slip Detector Possibly patentable: Patents Continuously Improving Predictive Traction Control

Start Order Parts & Materials 1 day Finish Test & Optimize 4 weeks Program PSo. C with Physics Model & Interpolation 3. 5 weeks Build Restrictor Install Restrictor 2 weeks 1 week Create Controller based on Design Criterion 2. 5 weeks Commissioning The Plan Critical Path ~10 weeks

Questions? Comments?

The End Thank you!