基于摩擦补偿的电液作动器高精度控制

电液作动器因其集成度高、占用空间小,容易组成分布式集中控制系统,在航空航天与工程机械领域飞速发展,但是在低速运行工况下,由于摩擦力以及液压系统的非线性等因素,难以完成高精度轨迹跟踪工作甚至产生低速爬行。为此,从摩擦特性对电液作动器轨迹跟踪精度的影响出发,提出一种前馈补偿+ESO的控制策略,引入LuGre动态摩擦力中的鬃毛平均变形量,建立精确伺服系统状态空间方程,在Simulink平台上搭建摩擦力模型和泵控非对称缸模型,采用正弦位置指令对该解决方案的轨迹跟踪精度进行了仿真验证。结果表明:前馈补偿+ESO的控制策略跟踪误差仅为常规PID控制的1/4,跟踪精度达到0.2 mm。

High Precision Control of Electro Hydraulic Actuator Based on Friction Compensation

The electro-hydraulic actuator has high integration and small space occupation, and is easy to form a distributed centralized control system. It has developed rapidly in the field of aerospace and engineering machinery. However, under low-speed operating conditions, it is difficult to complete high-precision trajectory tracking and even occurs low-speed crawling due to friction and nonlinearity of hydraulic system. Therefore, starting from the influence of friction characteristics on the trajectory tracking accuracy of electro-hydraulic actuator, a control strategy of feedforward compensation+ESO(extended state observer)was proposed, the average deformation of mane in LuGre dynamic friction was introduced, the state space equation of accurate servo system was established, and the friction model and pump controlled asymmetric cylinder model were built on Simulink platform. The trajectory tracking accuracy of the solution was simulated and verified by sinusoidal position command. The results show that the tracking error of feedforward compensation+ESO control strategy is only 1/4 of that of conventional PID control, and the tracking accuracy reaches 0.2 mm.