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Active Front Wheel Steering System (AFS). Chapter 2. Conventional Steering System. Rack and pinion system Constant steering ratio Fully mechanical system. AFS. Wheel steer angle = superposition of steering wheel angle and AFS actuator Variable steering ratio
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Active Front Wheel Steering System (AFS) Chapter 2
Conventional Steering System • Rack and pinion system • Constant steering ratio • Fully mechanical system
AFS • Wheel steer angle = superposition of steering wheel • angle and AFS actuator • Variable steering ratio • Combination of mechanical and electrical systems
Assumptions in modeling and control AFS • S Fx = 0 (No braking or throttle inputs) • Fyf = Cf af • Fyr = Cr ar Where Cf = cornering stiffness of front tires Cr = cornering stiffness of rear tires a = wheel side slip angle
Yaw Rate AFS Non-AFS
Simulation Data • m=3950 • Iz=6172 • Lf=1.1 • Lr=1.36 • Cf=71600 • Cr=77130 • Vx=20 • Lw=0.4