Backward Path Tracking for Tractor-Semitrailer System Based on Sliding Model Control

A backward path tracking control of a tractor-semitrailer system was presented.The kinematic nonlinear model of a tractor-semitrailer system was developed in polar coordinate system.To simplify process of solving，reference path's arc length of semitrailer was taken as argument.Since tractor-semitrailer system was a nonlinear multi-input and multi-output model with strong couplings，accurate linearization algorithm was employed to overcome unknown nonlinearities and uncertain parameters.Sliding mode variable structure control was employed for linearized tractor-semitrailer system.In order to ensure that semitrailer approached desired path quickly and reduce chattering，exponential approach law and the quasi-sliding mode control were adopted.To determine poles to obtain transition performances preserving system stability，pole placement algorithm was used to design control law.Finally，backward path tracking algorithm controlled the system to follow a circle path in real time.The results suggested that simulated tractor-semitrailer system's tracking path was smooth and almost identical to reference path.