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Published byClementine Turner Modified over 9 years ago
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Dynamic Traction Control By: Thiago Avila, Mike Sinclair & Jeffrey McLarty
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Motivation Drastically improve vehicle performance and safety by maintaining optimal wheel traction in all road conditions
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Motivation
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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
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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
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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 Physics Model (Saturator) ECU RPM Throttle Pos. Driver Pedal Slip Angle Radius External Sensors X/Y/Z Acceleration + - CBR 600 F4i Engine Wheels Wheel Slip Detector μs/μkμs/μk
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Physics Model
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Torque Map
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Interpolation Interpolate Between Four Points on Torque Map Interpolate between Engine Speeds at Throttle 1
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Interpolation Interpolate Between Four Points on Torque Map Interpolate between Engine Speeds at Throttle 1 Interpolate between Engine Speeds at Throttle 2
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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
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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
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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
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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 @ T(0) Calculate Vertical Force @ T(0) Calculate Coefficient of Friction and Update Model μ s Calculate Coefficient of Friction and Update Model μ s
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Optimize Performance No Slip Detected Is μ s at the limit? No Slip Detected Is μ s at the limit? Maintain current μ s Increase μ s Yes No New Limit Initial Value 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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Servo Rotary Potentiometer Gears Butter -Fly- Valve
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Electronic Restrictor
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Patents Physics Model (Saturator) ECU RPM Throttle Pos. Driver Pedal Slip Angle Radius External Sensors X/Y/Z Acceleration + - CBR 600 F4i Engine Wheels Wheel Slip Detector μs/μkμs/μk
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Patents Physics Model (Saturator) ECU RPM Throttle Pos. Driver Pedal Slip Angle Radius External Sensors X/Y/Z Acceleration + - CBR 600 F4i Engine Wheels Wheel Slip Detector μs/μkμs/μk Possibly patentable: Continuously Improving Predictive Traction Control
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1 day 2 weeks 1 week 2.5 weeks 4 weeks Commissioning The Plan Start Create Controller based on Design Criterion Finish Install Restrictor Order Parts & Materials Build Restrictor Test & Optimize Critical Path ~10 weeks 3.5 weeks Program PSoC with Physics Model & Interpolation
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Questions? Comments?
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The End Thank you!
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