Optimal Autonumous Steering Control Design and Trajectory Planning for Towbarless Aircraft Taxiing System

Efficient and safe aircraft scheduling scheme is of great significance to the construction of smart airport. The towbarless aircraft taxiing system is a common dispatching method, which is composed of the towbarless towing vehicle and the aircraft. In order to increase the steering accuracy and the efficiency and safety of dispatching, the autonomous steering control and trajectory planning of the system are studied. In this paper, the towbarless aircraft taxiing system is transformed into tractor-trailer system, and the kinematic model of the aircraft tractor is established. A force sensor is installed at the joint of the tractor and the aircraft wheel to obtain the force acting on the tractor. Taking the tractor as a virtual subsystem of towbarless aircraft taxiing system, and it is regarded as the controlled object of path tracking. An improved reference trajectory generation method based on two-layer optimal control is developed to generate reference trajectories. In the first layer, calculate the steering Angle of the tractor, a reed-shepp curve with artifical expertise in selecting intermediate nodes is introduced to provide an initial guess, generating the initial trajectory of the virtual subsystem. Then, the results obtained from the first layer are used as part of the state control variables of the trajectory planning of the original intact towbarless aircraft taxiing system of the second layer. A tracking controller based on model predictive control (MPC) is designed to compensate the pulling/pushing forces of the tractor in real time and drive the system into the desired trajectory. Finally, simulation experiments are carried out to verify the two-layer optimization control method. The experiments show that the optimization method has good performance of steering path tracking, and achieves high precision tracking of standard trajectory in the presence of interference variables in the environment.