气动薄膜执行机构模型优化及参数辨识

Model optimization and parameter identification of pneumatic membrane actuators

摘要:

在气动调节阀中，针对智能电气阀门定位器控制算法的开发通常需以气动薄膜执行机构模型为基础；本研究对应用于气动薄膜执行机构的传统Karnopp摩擦模型进行了优化，对动静摩擦判断条件DV(临界速度)进行修改，修改后的模型解决了DV如何选取这一问题。同时对传统气动薄膜执行机构模型的参数辨识方法进行改进，将多元线性回归和最小二乘法应用于估算气动薄膜执行机构中移动部件质量，弹簧刚度系数，预紧力，库伦摩擦和粘滞摩擦系数，通过实际气室压力和估计气室压力的标准误差、相关系数与参数向量中每个参数对应的p-value三个指标来决定参数的选取结果。将摩擦模型整合进气动薄膜执行机构动力学模型中，通过仿真和实验验证了参数辨识方法有效性。在开环不同幅值的阶跃信号和随机信号激励下进行仿真和实验对比，结果表明，整合后的摩擦模型能准确模拟气动薄膜执行机构的动态过程，该模型和参数辨识方法同样适用于其它机械装备。

Abstract:

In pneumatic control valves, the development of control algorithms for intelligent electrical valve positioners usually needs to be based on the pneumatic membrane actuator model; In this study, the traditional Karnopp friction model applied to pneumatic membrane actuators is optimized, and the dynamic and static friction judgment condition DV (critical speed) is modified, and the modified model solves the problem of how DV is selected. The parameter identification method of the traditional pneumatic membrane actuator model is improved, and the multiple linear regression and least squares method are applied to estimate the mass of moving parts, spring rate coefficient, preload force, Coulomb friction and viscous friction coefficient in the pneumatic membrane actuator, and the parameter selection result is determined by the actual air chamber pressure and the standard error of the estimated air chamber pressure, the correlation coefficient and the p-value corresponding to each parameter in the parameter vector. The model is integrated into the dynamic model of pneumatic thin film actuator, and the effectiveness of the parameter identification method is verified by simulation and experiment. Simulation and experimental comparison are carried out under the stimulus of step signals and random signals of different amplitudes of open-loop, the results show that the integrated friction model can accurately simulate the dynamic process of pneumatic membrane actuator, the model and parameter identification method are also applicable to other mechanical equipment.