Automatic Parallel Parking of Car-Like Mobile Robots Using Saturation Control and Bang-Bang Control

In this paper, we consider the parallel parking problem of car-like mobile robots. First, a kinematic model of the robot suitable for control applications has been derived. The problem of stabilizing the robot is seen as an extension of the tracking problem. Two types of steering controllers for straight-line tracking: bangbang (optimal) control and saturated control have been proposed. Due to the discontinuity of the control law, the performance of the system when a bang-bang control is used may be highly oscillatory. We demonstrate that the saturated control which is continuous, achieves also a quick steering of the system near to the origin, and this type of control can be successfully used in solving automatic parking problems. An approach of using saturated control with two different levels of saturation is proposed, in order to obtain a larger area of the staring configurations of the mobile robot for the first reverse manuever of the parallel parking. The robot can be automatically parked by using one or multiple maneuvers, depending on the size of the parking space. Simulation results confirm the effectiveness of the proposed control schemes. Key-Words: Car-like mobile robot, parallel parking maneuver, bang-bang control, saturated control