Design of Active Suspension Control Systems for a Flexible Vehicle Body

从节能的角度出发，高速地面车辆需要设计一种轻量化的车身。但也会出现一些问题，如柔性结构的弹性振动，导致平顺性不佳，运行稳定性差。在这种情况下，需要主动悬架来实现车辆在崎岖路面和轨道上行驶时的高稳定性和平顺性。首先，搭建了一套实验装置，通过气动弹簧和执行器来悬挂车身的比例模型，执行机构的压力由伺服阀控制。伺服阀由脉宽调制(PWM)驱动，并采用垂直加速度数字PID补偿和最优反馈控制律进行控制。这些反馈控制系统是由一台16位微型计算机实现的。实验结果表明，与被动系统相比，4.5HZ共振频率处的振动幅值得到了高达70%的抑制。其次，提出了采用集中控制和分散控制的多变量控制方法，设计具有前后悬架的柔性车身控制系统。这些控制系统的目的不仅是为了抑制刚体运动，而且是为了抑制结构振动。计算机仿真结果表明，主动控制悬架明显改善了柔性车辆的平顺性和稳定性。

From a viewpoint of energy saving, it is required to design a lightweight vehicle body for high speed ground vehicles. But some problems will occur such as an elastic vibration of the flexible structure which leads to an uncomfortable ride quality and bad running stability. In such cases, active suspensions are required to realize a high stability and ride quality of the vehicles running on rough surface of roads and tracks.At first, an experimental apparatus has been made up so that the scale model of the vehicle body is suspended by the pneumatic spring and the actuator, the pressure of which is controlled by servo-valves. The servo-valves are driven by PWM (Pulse Width Modulation) and controlled by both the digital PID compensation of the vertical acceleration and the optimal feed back control law. These feed back control systems are realized by a 16 bit micro-computer. According to the result of this experiment, the amplitude of the vibration at resonant frequency 4.5 Hz is sufficiently suppressed up to 70 % the passive system.Next, it is proposed to design the control systems of a flexible vehicle body with front and rear suspensions, by use of multi-variable control method of centralized and decentralized controls. These control systems are aimed to suppress not only rigid body motions but also structural vibrations. According to the computer simulation, it is found the ride quality and the stability of the flexible vehicles are clearly improved by the actively controlled suspensions.