含间隙非线性的电液数字控制系统失控采样频率的确定

Determination of Uncontrolled Sampling Frequency of the Electro-hydraulic Digital Control System with Clearance Nonlinear

针对一个液压缸活塞杆与负载处存在传动链间隙的电液数字控制系统,考虑了系统活塞杆运动越过间隙时所受力的突变过程、负载转动惯量较大及支点处摩擦力较大等因素,建立了含间隙非线性和零阶保持器的电液数字控制系统数学模型,利用Matlab/Simulink软件,分析了间隙为固定值时不同采样频率下系统的响应特性。一个具体实例仿真结果表明:在含间隙非线性的电液数字控制系统中,当间隙值一定时,存在一个导致系统失控采样频率区,当系统采样频率进入该区时,系统超调量增加,震荡和冲击加剧,调节时间变长,甚至出现极限环振荡而失控,系统采样频率的选择必须避免进入该失控区内。

Based on an electro-hydraulic sampled-data control system with transmission chain clearance between the load and the piston rod, the factors that the mutation process of force when piston rod movement across the gap in the system when the mutation process of force, the bigger moment of inertia of the load and the bigger friction in the fulcrum are considered, and the model of the electro-hydraulic sam- pled-data control system with clearance nonlinear and zero order retainer is established. Using Matlab software, the response characteristics of the system under different sampling period are analyzed when the clearance is a certain value. The simulation results of a specific exam- ple show that, when the clearance is a certain value, a sampling frequency region that makes the system uncontrolled is existed; when the sampling frequency of the system goes into this region, the system overshoot volume increase, shock and impact intensify, and adjust time is longer, and even appear limit cycle oscillation and out of control, so the choice of sample frequency must avoid entering uncontrolled zone of the system.