Hybrid Vibration Control Adapting to State Variation of Suspension System

为了验证悬架刚度的变化规律，采用多体动力学理论对悬架进行了分析。仿真结果表明，其冲程末端附近的刚度比名义状态下的要高。此外，还估计了冲程结束时的冲击量，并研究了抑制冲击的方法。从额定阻尼值切换到更高的阻尼值可能会使加速度响应变差。分析了悬架接近行程末端前启动执行器的重要性，采用滑模控制方法设计了控制系统，以提高悬架的额定性能，并在行程末端刚度变化的情况下保持其正常工作状态。设计了变结构系统观测器来估计1/4车辆悬架系统的状态，并进行了实验。在实验装置中，采用直线电机作为执行机构，交流伺服电机作为激振器，产生路面扰动。VSS观测器利用了车辆的加速度，不需要随着行程接近终点而变化的刚度力。用直线电机模拟了悬架刚度的非线性作用力。通过仿真和实验，验证了实验结果与仿真结果的一致性，所设计的控制器对悬架系统的非线性状态变化具有较强的适应性。

In order to verify variation of suspension stiffness by considering its geometry, the suspension was analyzed using multi-body dynamics theory. It was verified from the simulation results that the stiffness at around its stroke end becomes higher than that in the nominal state. Also, the amount of shock at the stroke end was estimated and the method to suppress the shock was examined. The switching control from nominal damping to higher damping may make the acceleration response worse. It was found out that it is important to activate the actuator before the suspension approaches to its stroke end.By using sliding-mode control method, the control system was designed in order to improve the nominal performance and maintain it even when the stiffness changes in the stroke end. VSS (variable structural system) observer was designed to estimate the state of the quarter-car suspension system and the experiments are performed. A linear motor was used as the actuator in the experimental setup and the AC servo motor was used as the shaker to generate the road disturbance. VSS observer utilized the acceleration of the vehicle and did not need the stiffness force varying as the stroke approaches the end. The nonlinear force of the suspension stiffness was simulated by the linear motor. By carrying out simulations and experiments it was verified that the experimental results coincide with the simulation results and the controller designed was adaptable to the state varying according to the nonlinearity of the suspension system.