关键词: 线控转向；模糊控制；转向输入频率；变角传动比

Abstract: In order to improve the maneuvering stability of a vehicle with steer-by-wire control, this paper firstly investigates the vehicle response in different speed domains to determine the change characteristics of the vehicle steady state gain. Secondly, the vehicle response of different steering wheel input frequencies is analyzed, and the steering input frequency is taken as the threshold condition for mode switching. Then, the relationship between the steering wheel center position and the "dead zone" is investigated to design the incremental law of the transmission ratio. Finally, a fuzzy controller with variable structure ratio is designed based on multi-factor analysis, and simulation is carried out under typical working conditions. The results show that the turning radius of the vehicle under low speed is obviously smaller than that of the mechanical steering system in the steady state slewing test condition, and the response of the swing angle speed decreases with the increase of the vehicle speed, but it is still higher than that of the mechanical steering system, which is in line with the design requirements of the ideal transmission ratio. Meanwhile, in the intermediate steering test condition, the lateral displacement of the vehicle under this strategy is smaller, which is in line with the expectation that a larger steering input is required in the intermediate steering position.

Key words: Steer-by-wire; Fuzzy control; Turn to input frequency; Variable angle transmission ratio