Integrated Chassis Control and Control Allocation for All Wheel Drive Electric Cars with Rear Wheel Steering

Abstract

This study investigates a control strategy for torque vectoring (TV) and active rear wheel steering (RWS) using feedforward and feedback control schemes for different circumstances. A comprehensive vehicle and combined slip tire model are used to determine the secondary effect and to generate desired yaw acceleration and side slip angle rate. A model-based feedforward controller is designed to improve handling but not to track an ideal response. A feedback controller based on close loop observation is used to ensure its cornering stability. The fusion of two controllers is used to stabilize a vehicle’s lateral motion. To increase lateral performance, an optimization-based control allocation distributes the wheel torques according to the remaining tire force potential. The simulation results show that a vehicle with the proposed controller exhibits more responsive lateral dynamic behavior and greater maximum lateral acceleration. The cornering safety is also demonstrated using a standard stability test. The driving performance and stability are improved simultaneously by the proposed control strategy and the optimal control allocation scheme.

Review of Integrated Chassis Control Techniques for Automated Ground Vehicles

“…Bias can occur during the integration procedure shown in (5); therefore, to eliminate the bias, an additional term, based on measured and modelled acceleration, is added to the formula. Modelled acceleration can be achieved from tyre forces, as described in [ 69 ]: where and are lateral forces at the front and rear axles of the vehicle, which depend on tyre slip, yaw rate, velocity, and friction, and is the vehicle mass. There is external wheel force measurement equipment from Kistler and other manufacturers, which can be placed on vehicle demonstrators.…”

“…Designing ICC for EVs requires careful consideration of the fact that the energy consumption of active subsystems may affect the overall energy efficiency, potentially reducing the vehicle’s mileage per charge [ 68 ]. Transitioning from high-level feedback controllers, which are common in many ICC variants [ 69 ], to feedforward solutions can mitigate the issue of increased energy consumption [ 70 ].…”

“…Bias can occur during the integration procedure shown in (5); therefore, to eliminate the bias, an additional term, based on measured and modelled acceleration, is added to the formula. Modelled acceleration can be achieved from tyre forces, as described in [69]:…”

Research on Yaw Moment Control System for Race Cars Using Drive and Brake Torques

“…A typical example of the former is active rear-wheel steering. As the name suggests, this controls yaw moment by dynamically changing the rear tire slip angle, thereby changing the lateral force on the rear tires [1][2][3]. Since many vehicles have a longer wheelbase than track, it is expected that the yaw moment can be varied efficiently.…”