基于简化模型的阀控液压缸活塞运动速度控制方法的研究

对阀控液压缸活塞运动速度的有效控制,有利于提高液压伺服系统的工作精度。设计一种与非线性摩擦力相关的简化模型,用以对液压缸活塞运动速度进行控制。分析比例方向阀控制的液压缸的结构,建立比例方向阀的闭环传输函数。通过液压缸两个腔室的压差,计算比例方向阀中液压介质的体积流量方程,并在此基础上求取液压缸压力值的连续方程,进而得到了液压缸活塞运动速度与非线性摩擦力之间的全阶模型。最后,在闭合的液压回路中,通过负载的压力值,简化了液压缸压力值的连续方程,从而求取了液压缸活塞运动速度与非线性摩擦力之间的简化模型。实验中,利用此方法对方波、正弦波以及随机激励信号产生的目标速度进行了追踪测试。测试结果显示:此方法相比滑模控制方法,在对方波、正弦波以及随机激励信号下产生的目标速度进行追踪时,追踪误差分别减少了9.2%、11.22%以及11.13%。说明此方法能够对液压缸活塞运动速度进行准确的控制。

Research on Piston Motion Velocity Control Method for Valve-controlled Hydraulic Cylinder Based on Simplified Model

Effective control on piston motion speed of valve controlled hydraulic cylinder is conducive to improving the working accuracy of hydraulic servo system. A simplified model related to the non linear friction force was designed to control the piston velocity of the hydraulic cylinder. The structure of the hydraulic cylinder controlled by a proportional directional valve was analyzed, and the closed loop transfer function of the proportional directional valve was established. Then, through the pressure difference between the two chambers of the hydraulic cylinder, the volume flow equation of the hydraulic medium in the proportional directional valve was calculated. On this basis, the continuous equation of the pressure value of the hydraulic cylinder was obtained, and the full order model between the piston velocity of the hydraulic cylinder and the non linear friction force was obtained. Finally, in the closed hydraulic circuit, the continuous equation of the hydraulic cylinder pressure value was simplified by the pressure value of the load, and the simplified model between the piston velocity of the hydraulic cylinder and the non linear friction force was obtained. In the experiment, the target velocities generated by square wave, sine wave and random excitation signal were tracked and tested. The test results show that the tracking error of this method is reduced by 9.2%, 11.22% and 11.13% respectively compared with sliding mode control method when tracking the target velocity under the conditions of square wave, sinusoidal wave and random excitation signal. It shows that this method can be used to accurately control the motion speed of piston in hydraulic cylinder