Steering Control Strategy for Vehicle-based Autonomous Cooperative Transportation Systems

This paper presents a steering control strategy for the establishment of vehicle-based autonomous cooperative transportation systems (CTSs). The concept of a CTS for vehicle-based platforms using the Ackermann steering mechanism remains to be fully understood. The main function of the vehicle-based CTS considered herein is to transport large cargo while keeping multiple vehicles spaced apart from each other. Such synchronized driving requires appropriate control of the steering and acceleration of the vehicles, and this study focuses on the steering aspect. In a synchronized vehicle cluster, one vehicle is arbitrarily designated as the master vehicle while the other vehicles represent slave vehicles; based on master–slave relationships, the slave vehicles follow the master vehicle at constant gaps. As an example, two vehicles are assumed to be driving parallelly with a fixed lateral offset. A virtual vehicle trajectory with a constant lateral offset from the master vehicle is generated. The steering control system corrects the steering angle of the slave vehicle to reduce the position and yaw errors with respect to the virtual vehicle trajectory. An error vector comprising the position and yaw errors between the slave vehicle and the virtual vehicle is defined. The second derivative of this error vector is obtained kinematically, and the error dynamic equation based on vehicle dynamics is described using a bilinear control system. A steering control system based on error-state feedback is designed to allow the errors to converge to zero. The control performance is verified via computer simulations.