Multi-objective torque distribution strategy for hub motor electric vehicles under emergency steering conditions

doi:10.3969/j.issn.1674-8484.2025.02.004

Abstract

Abstract:

A multi-objective optimization strategy based on the non-dominated sorting genetic algorithmⅡ (NSGA-Ⅱ) was developed to improve steering stability and occupant comfort in hub-motor electric vehicles under emergency steering conditions. The strategy adopted a direct yaw moment control method to design the optimized objective function for handling stability and occupant comfort, taking into account generalized force equation constraints such as longitudinal desired torque and additional yaw moment. The optimal torque solution was selected in the pareto front calculated by NSGA-Ⅱ according to the dynamic conditions of the vehicle. The results show that compared to the axle load ratio (ALR) and weighted least squares (WLS) strategies, for high-speed steering, the root-mean-square errors of the vehicle sideslip angle and the yaw rate of the optimization strategy with respect to the reference values are reduced by 37.45%, 52.08%, and 41.98%, 56.95%, respectively, and the amplitudes of its lateral acceleration and torque are also smaller. The effectiveness of the proposed strategy for torque distribution during emergency steering of hub-motor electric vehicles is demonstrated to improve the vehicle steering stability and occupant comfort.

Key words: hub-motor electric vehicles, non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ), torque distribution, handling stability, occupant comfort

CLC Number:

U461.6

FAN Xiaobin, PENG Jiaxing. Multi-objective torque distribution strategy for hub motor electric vehicles under emergency steering conditions[J]. Journal of Automotive Safety and Energy, 2025, 16(2): 217-225.

Figures/Tables 14

References 19

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总质量，m	1 298 kg
质心到前轴距离，l_f	1.015 m
质心到后轴距离，lr	1.895 m
前轴轮距，B_f	1.675 m
后轴轮距，B_r	1.675 m
轮胎滚动半径，R_w	0.325 m
质心高度，h_g	0.54 m
车辆绕Z轴的转动惯量，I_z	1 536.7 kg · m²
电机最大转矩，T_max	200 Nm

总质量，m	1 298 kg
质心到前轴距离，l_f	1.015 m
质心到后轴距离，lr	1.895 m
前轴轮距，B_f	1.675 m
后轴轮距，B_r	1.675 m
轮胎滚动半径，R_w	0.325 m
质心高度，h_g	0.54 m
车辆绕Z轴的转动惯量，I_z	1 536.7 kg · m²
电机最大转矩，T_max	200 Nm

转矩分配策略	RMSE
转矩分配策略	β_d / rad	γ_d / (rad·s^-1)
ALR	0.024 3	0.033 6
WLS	0.026 2	0.037 4
NSGA-Ⅱ最优转矩分配策略	0.015 2	0.016 1

转矩分配策略	RMSE
转矩分配策略	β_d / rad	γ_d / (rad·s^-1)
ALR	0.024 3	0.033 6
WLS	0.026 2	0.037 4
NSGA-Ⅱ最优转矩分配策略	0.015 2	0.016 1