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An autonomous lanekeeping system for vehicle path tracking and stability at the limits of handling

September, 2014

This paper describes a feedforward-feedback steering controller designed to simultaneously achieve vehicle stability and accurate path tracking at the limits of handling. Steering feedback through a lookahead control scheme exhibits desirable stability properties at the limits of handling, but at the expense of significant path tracking errors. Results from a linear analysis show that lateral tracking error is minimized when the steering controller constrains vehicle sideslip to be tangent to the desired path. While incorporating this desired behavior into the steering feedback results in accurate lateral path tracking, the resulting closed loop system exhibits poor stability margins. However, applying the sideslip tracking behavior as a steady-state feedforward control law creates a robust steering controller capable of accurate path tracking and oversteer correction at the physical limits of tire friction. Experimental data collected from an Audi TTS test vehicle on a 1.3 km stretch of race track demonstrates the performance of the controller design.

Publication Location: 
12th International Symposium on Advanced Vehicle Control