Research on Shimmy Characteristics and Control Strategy of Double-Axle Steering Mechanism with Multiple Limit Cycles Considering Vehicle-Road Coupling

The vehicle and the road are a coupled system, the road surface characteristics have a great influence on the vehicle's handling stability and driving safety. So in this study, A 9-DOF mathematical model of dual-axle steering mechanism considering the vehicle-road coupling is established. Taking one multi-axle vehicle with dual-axle steering mechanism for example, the numerical calculation method is used to reproduce the multiple limit-cycles shimmy, and the effects of the road adhesion coefficient on the multiple limit-cycles shimmy characteristics is analyzed. The results show that the maximum swing angles of first and second axle and the speed ranges of multiple limit-cycles shimmy occurring decrease with the road adhesion coefficient decreasing, and as the road adhesion coefficient decreases, the speed range of multiple limit-cycles occurring tend to shrink to the middle speed range(40-50km/h) which is multi-axle vehicles often travelling. In addition, we also found that the multiple limit-cycles shimmy characteristic of the dual-axle steering mechanism is more sensitive to the change of the road adhesion coefficient of second axle than the change of the road adhesion coefficient of first axle. This finding can provide theoretical guidance for suppressing multiple limit-cycles shimmy of multi-axle vehicle with dual-axle steering mechanism. Finally, we propose a control strategy for the multiple limit cycle shimmy phenomenon, which reduces the amplitude of the shimmy and the interval of multiple limit cycles.