The Differential Braking Steering Control of Special Purpose Flat-bed electric Vehicle 2019-01-0440
Special purpose flat-bed vehicle is commonly utilized to move heavily items such as containers in warehouse, port and other freight handling scene. In recent years, with the increasing popularity of electronic system in vehicle, the hydraulic steering system have be gradually replaced by electric ones. However, as for flat-bed electric vehicle in load-carrying situation, the cost of electric steering system is high for commercial activities. Thus, for some corporates, the differential braking steering strategy becomes an ideal alternative, which only needs the independently braking function of each wheel. The purpose of this paper is to present a steering control method for flat-bed electric vehicle based on differential braking system. Unlike traditional steering system, the differential braking steering system required more complicated control to keep the motion trail. And since the load range of special purpose flat-bed vehicle is quite wide, the control rule needs to adjust accordingly as the load changing. There are two main components of the control method, steering while moving forward and pivot steering, and each of them was composed by upper layer and executive layer. Based on the specific reference models presented in this paper, the upper layer controller was designed adopting LQR control. To evaluate the practicability of the control methods, a 7-DOF flat-bed vehicle model was established in Simulink. According to the simulation results at different load, velocity and steering target, the control method proposed in this paper showed quite well performance and meet the basic demand of handling quality while response rapidly to the control target.
Keywords—Special purpose flat-bed vehicle; Differential braking; Steering control; Pivot steering; LQR control; Simulation