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建立了考虑车辆横摆、侧向以及侧倾运动的3自由度非线性整车模型;运用Lyapunov指数方法对所建立的非线性整车模型进行了混沌的数值仿真分析.通过最大Lyapunov指数图和分岔图发现,车辆的横向运动非常复杂,包含了倍周期、拟周期以及混沌运动,对于车辆极限工况时的横向运动稳定性是不利的.利用滑模变结构控制(sliding mode variable structure control,SMVSC)方法,设计了SMVSC控制器,对车辆横向运动中的混沌进行了控制.为了减少SMVSC控制系统的抖振,进一步提高车辆在极限工况下行驶的横向运动稳定性,采用了幂次趋近律,利用模糊控制的方法实现了趋近律的自适应策略.最后将所设计的自适应趋近律的SMVSC系统在Matlab中进行了仿真,并将未加控制,SMVSC控制以及自适应趋近SMVSC控制三种仿真结果进行了对比分析,发现采用了自适应趋近的SMVSC控制对混沌的控制效果比其他的都要好,有效抑制了车辆横向运动中的混沌,显著提高了车辆在极限工况下行驶的横向稳定性,充分证明了该控制策略是有效的.
A three-degree-of-freedom nonlinear vehicle model considering vehicle yaw, lateral and roll motions is established and the chaotic numerical simulation of the nonlinear vehicle model is conducted by using the Lyapunov exponent method.According to the maximum Lyapunov exponent map and The bifurcation diagram shows that the lateral motion of the vehicle is very complicated, including the period, the quasi-period and the chaotic motions, which are unfavorable to the stability of the lateral motion of the vehicle in the extreme conditions. By using sliding mode variable structure control , SMVSC) method, the SMVSC controller is designed to control the chaos in the vehicle lateral motion.In order to reduce the chattering of the SMVSC control system and further improve the lateral motion stability of the vehicle under the extreme conditions, the power Approaching the law and using fuzzy control method to achieve the adaptive law of the approach law.Finally, the designed SMVSC system of the adaptive approach law is simulated in Matlab, and the uncontrolled, SMVSC control and adaptive Approaching SMVSC control three kinds of simulation results were compared and analyzed, and found that using adaptive SMVSC approach to control the effect of chaos control more than other Better, effectively inhibits lateral motion of the vehicle in a chaotic, significantly improved lateral stability of the vehicle is traveling in extreme working conditions, the control strategy proved to be effective.