Analysis of handling stability for electric-driven articulated truck

Articulated steering trucks have two separate parts that are connected by an articulation joint. The articulated joint will decrease the lateral stability of truck while it drives at higher speeds. The electric-driven articulated truck discussed in this paper is composed of a diesel engine, generator, rectifier, inverter, and in-wheel-motor, among other components. It is driven by a diesel engine and in-wheel-motor with an AC-DC-AC driving mode. Each wheel of the truck is mounted with one in-wheel-motor, which can be driven independently. All-wheel independent drive systems of articulated trucks have some advantages, such as being space-saving, having a fast driving response time, and having accurate control of the driving forces on each wheel. This paper proposes a direct yaw-moment control (DYC) method to enhance the stability behaviors of articulated vehicles for the each wheel to be controlled independently. The modified 3 DOF vehicle dynamics model is built based on the structural features of the articulated steering truck. The feedforward and feedback controller is designed with the mass center slip angle and yaw angular velocity of the front body and the mass center slip angle and yaw angular velocity of rear body set as separate variables. This approach combines the feedforward compensation for the mass center slip angle and yaw angular velocity, and the feedback compensation based on the deflection of real transient output and ideal output of vehicle to control the vehicle movement. The factors of feedforward and feedback compensation are determined by the optimal control strategy based on a linear quadratic regulator (LQR). The two optimal DYC controllers for the yaw stability of articulated vehicles are designed based on the different control variables. The 35 ton electric-driven articulated dump truck was simulated to verify the effectiveness of DYC control strategy for improving the yaw stability of vehicle. The vehicle dynamics simulation model generated by MATLAB/Simulink software is used to perform a transient step response analysis of articulated trucks. The performance of vehicle stability is compared and analyzed from the aspects of response time and accuracy under the two proposed DYC control methods. The values of yaw angular velocity, mass center side slip angle, and lateral acceleration are used to evaluate the lateral dynamics performance of articulated truck. The computer simulation results show that the two control strategies are feasible and correct. Both of them can realize the control target on enhancing articulated truck stability. The controlling effects of these two DYC methods on the articulated truck are compared from the aspects of yaw rate and mass center slip angle simultaneously. The simulation results suggest that the dynamic stability behavior of articulated trucks with the optimal DYC control acting on the front body is better than that of the optimal DYC control on the rear body.