Pitch stability control of variable wheelbase 6WID unmanned ground vehicle considering tire slip energy loss and energy-saving suspension control

Abstract

Acceleration on a ramp and emergency braking are common driving conditions for special vehicles. Due to the complex coupling between the suspension and the chassis structure, the body attitude maintenance and stability control face huge challenges. Aiming at the control problem of pitch stability of the existing six-wheel independent drive unmanned vehicle (6WID UGV) with variable wheelbase during acceleration and deceleration, this paper designs an interconnected active hydro-pneumatic suspension (IAHPS) that can autonomously adapt to the change of wheelbase. Based on this system, a pitch stability control strategy considering the lowest energy consumption of the chassis is proposed. Firstly, a PID-type sliding mode controller (SMC) is used in the upper controller to calculate the desired anti-pitching torque. The disturbance caused by the nonlinearity and uncertainty of the model is estimated by the extended state observer (ESO). Secondly, with the goal of minimizing the energy consumption of the suspension system, the PSO algorithm is used in the middle controller to decide the pressure of the two accumulators in IAHPS. Thirdly, the lower controller again uses the PSO algorithm to achieve wheel torque distribution to minimize tire slip energy loss; Finally, simulation tests in multiple scenarios verify the effectiveness of the designed layered control strategy in terms of the pitching stability control. Under random road and horizontal road, the energy consumption for active adjustment of suspension is reduced by 28.35% and 29.41% respectively; The total energy loss of tire slip is reduced by 65.16% and 41.52%.