Development of Active Rear Axles Steering Controller For 8X8 Combat Vehicle 2020-01-0174

Lateral dynamic control considered to be crucial to enhance the handling characteristics and stabilization of a vehicle as a safety demand. In this paper, active rear axles steering control system will be developed using an optimal quadratic regulator (LQR) control methodology. The controller aims to minimize the vehicle side slip and consequently increase its handling stability and transient state performance. The controller design has been utilized the independent steering of the vehicle’s 3^rd and 4^th axles as control inputs. Furthermore, the developed controller will be combined with a feedforward zero side slip (ZSS) controller based on the steady-state model of the vehicle and satisfying the Ackermann steering condition. In addition, the steady-state handling performance will be evaluated using the Skid Pad test. The transient state performance will be assessed at low Coefficient of Friction (CoF) surface using FMVSS 126 Electronic Stability Control (ESC) system test speed, while Open Loop Step Slalom Test will be used for assessing the controller at high CoF. The controllers will be implemented using MATLAB Simulink and will be simulated in a co-software simulation environment with Truck- Sim software. The results show a notable improvement in the steady and transient states handling performance in comparison with the Conventional, where the 3^rd and 4^th axles are fixed, and active 4th axle vehicle, where the 3^rd axle is fixed. In addition, the controller succeeded to prevent the vehicle rollover and maintain a stable trajectory.