Nonholonomic equivalent disturbance based backward motion control of tractor-trailer with virtual steering

This paper describes a strategy of backward motion control in a tractor-trailer system. The backward motion of a tractor-trailer requires skilled control, because the position and orientation of the trailer can only be controlled by an input to the tractor. When a driver changes orientation while driving backward, the steering angle must be skillfully controlled. This operation is different in the case of a single vehicle moving backward. An uncontrollable situation of a tractor-trailer motion often happens, for example, the "jackknife phenomenon." Such a situation is often induced by the nonholonomic constraint of a wheeled system. In this research, virtual steering is introduced to a trailer. This virtual steering controls the orientation of the trailer and suppresses the nonholonomic equivalent disturbance. With this virtual steering, the tractor-trailer is able to track a straight trajectory in backward driving independently of the nonholonomic constraint. Several numerical and experimental results are shown to confirm the validity of the proposed approach.