Path Tracking Control for Urban Autonomous Driving

A path tracking controller for autonomous vehicles in urban environments is presented. Based on system inversion, the steering angle causing the vehicle to follow the path in absence of disturbances is calculated. Then, the lateral distance and the orientation error w.r.t. the path are compensated by a state feedback controller. Further, a decoupling of the velocity is considered in the system-inversion and the feedback controller. Therefore, ideally, the velocity does not influence path tracking and, hence, the requirements on velocity control are relaxed. To reduce the effort for parameter identification, the controller is intentionally based on a kinematic vehicle model requiring less parameters compared to an elaborated dynamic model. It is assumed that the effects of unconsidered system components, e.g., tire slip, are then compensated by the state-feedback controller. The approach is validated on a closed proving-ground in a simulated urban scenario. Herein, for driving velocities up to 14 m/s and curve radii of down to 10 m, an RMS tracking error for the lateral distance to the path of 7.2 cm was achieved. The control system will be used in TomTom's autonomous car 'Trillian' that serves as a validation and research platform to evaluate high definition maps of road networks. Copyright (C) 2020 The Authors.