Abstract:

In this paper， the parking path following method based on the differential flatness theory decouples the error between the vehicle and the path reference point horizontally and longitudinally， and uses the controller corresponding to the horizontal and longitudinal error to control， so that the vehicle can follow the reference point moving with the path more accurately and finally realize more accurate following of the whole parking path. For longitudinal control， integration of effective distance is proposed and the longitudinal error correction rules are set， so as to ensure that the error between the reference point of the vehicle is the transverse error that can be controlled laterally to the largest extent. For lateral control， linear quadratic regulator （LQR） is used. And the relationship between curvature changing rate and decay factor α， which can accelerate the damping of lateral error， is established to make the vehicle follow the reference point accurately when the curvature of the path changes or not. Simulations and real-vehicle tests show that the improved transverse and longitudinal path following control strategy can make the whole process follow the reference point more accurately and realize more accurate path following.

Key words: automatic parking, path following, lateral and longitudinal decoupling, differential flatness