An optimal torque allocation strategy for improving handling stability of hub motor electric vehicle

Abstract

The performance of the hub motor electric vehicle (HMEV) under poor road conditions is closely linked to occupant safety. To address this issue, this paper presents a hierarchical optimization-based torque strategy designed to enhance handling stability. The formulation of the optimization problem and constraints into a new objective function is incorporated to ensure that the vehicle can gain the ability to maintain a steady state even under stringent constraints. The active set method (ASM) is employed as the optimization algorithm. The results of the double lane change (DLC) simulation on a simulated wet road surface indicate that the optimization-based strategy more effectively tracks the reference values of the vehicle sideslip angle and yaw rate, with the mean tire load rate and the standard deviation of trajectory deviation reduced by 38.14% and 20.12%, respectively, compared to the average allocation strategy. The results of the road experiments show that the mean tire load rate of the optimization-based strategy decreases by 29.39%, with smaller fluctuations in the vehicle sideslip angle and yaw rate compared to the average allocation strategy. These results indicate that the optimization-based strategy provides a greater lateral safety margin for the tires, thereby enhancing vehicle handling stability on low road adhesion coefficient surfaces.