中文摘要：

半挂汽车列车载运工况变化较大,横向失稳机制复杂,给整车及稳定性控制系统的开发设计带来困难。应用非线性动力学的相关理论,研究半挂汽车列车在极限操纵工况下的平衡点分岔、相轨迹和Hopf分岔特性以及与载运工况的关系;在此基础上,结合不足转向梯度和系统阻尼特性对不同横向失稳形式的发生机制进行探讨。结果表明,载运工况的变化可能导致系统出现鞍结分岔、Hopf分岔和同宿轨道等非线性动力学现象;牵引车后轴侧滑而导致折叠是半挂汽车列车主要的横向失稳形式,挂车甩尾与折叠密切相关,挂车甩尾会同时加剧牵引车侧滑而加剧折叠,横向摆振与Hopf分岔密切相关,一般仅在载重较大且半挂车质心显著靠后才可能发生,且横向摆振失稳一般都会进一步发展到折叠而完全失控,选择牵引车横摆角速度和挂车侧偏角为控制变量设计稳定性控制系统有望取得较好的效果。

英文摘要：

Since the lateral dynamics of a tractor semi-trailer vehicle is rather complex resulting from the large variations of the load and the centre of mass（CM） of the trailer,it becomes difficult to design the stability control system.The nonlinear dynamics and the lateral stability of the tractor semi-trailer vehicle is investigated.The relations of the lateral stability,equilibrium bifurcation and Hopf bifurcation with the load scenarios are analyzed in detail.Combining the means of understeer gradient and damping ratio,the lateral instability and mechanisms are discussed.The results reveal that nonlinear dynamical phenomena such as saddle-node bifurcation,Hopf bifurcation and homoclinic orbit are identified in critical cornering situations.For a typical tractor semi-trailer vehicle,jackknife caused by the sideslip of the rear axle of the tractor is the primary way to lead the vehicle to lateral instability.Trailer oscillation which is much related to Hopf bifurcation generally occurs when the load weight is considerably large and the trailer CM is much near to the rear axle of the trailer.Further,trailer oscillation is prone to further develop to jackknife and trailer swing often causes the whole vehicle including the tractor to sideslip with jackknife occurring simultaneously.Rather satisfying control performance is expected to be obtained by selecting the tractor yaw rate and trailer slip angle as the control variables to design vehicle stability control system.