Modelling and Active Safe Control of Heavy Tractor Semi-Trailer

The active safety and stability of tractor semi-trailer have becoming big concern among the road transportation industry. The paper sets up a six-axle plane dynamic model for simulating the yaw/roll stability of heavy tractor semi-trailer using Matlab/Simulink. LQR controller is chosen to produce the optimum compensate yaw moment to correct the vehicle path based on the bias of yaw rate and lateral acceleration respective. The allocation strategy of braking moment can allocate the braking moment to unique wheel at particular moment, which is the differential braking. At the same time, PD controller can regulate the longitudinal slip ratio of tires to make it work at optimum slip ratio nearby to obtain maximum brake force. The simulation results show that yaw-roll stability of tractor semi-trailer has improved effectively after applying the differential braking.