A Comparison of the Relative Benefits of Active Front Steering and Active Rear Steering When Coordinated With Direct Yaw Moment Control

Abstract

Abstract This paper studies the benefits of coordinating stability and steerability controllers to reduce vehicle deceleration during limit handling situations. The stability controller, DYC, uses the vehicle brakes to apply a restoring moment when the vehicle sideslip angle and sideslip velocity exceed fixed bounds. This use of the brakes interferes with the longitudinal dynamics of the vehicle in a way that drivers find undesirable. Active front steering (AFS) and active rear steering(ARS) can be used to tune the vehicle handling balance in the low to mid-range lateral-acceleration regime. Earlier work has shown that the use of AFS can reduce the interference observed using DYC alone. The levels of improvement achievable by coordinating AFS and ARS with DYC are quantified using open loop handling simulations tests by predicting the deceleration of the vehicle in an extreme manoeuvre. The results from these simulations are compared to assess the relative benefits of AFS and ARS when coordinated with DYC. The computer simulations are based on a four-degree of freedom vehicle model incorporating longitudinal, lateral, yaw, roll, and load transfer effects.