精密实验平台的非线性摩擦建模与补偿

Nonlinear friction modeling and compensation of high-precision experimental platforms

非线性摩擦是影响高精度机械伺服系统动静态性能的主要因素之一。针对精密实验平台随行程位置不同表现出不同的摩擦特性,提出了一种基于LuGre模型的改进型摩擦建模方法,以速度和行程位置信号作为模型的输入变量,并用遗传算法对该模型的动静态参数进行辨识。基于改进型摩擦模型,分别通过精密实验运动平台及其相应的伺服仿真平台进行了摩擦现象和摩擦前馈补偿的实验和仿真。实验结果表明,摩擦补偿后的跟踪误差值约为补偿前的1/3,系统的静差也由原来1.4μm减小到0.4μm,与仿真平台摩擦补偿前后的现象基本一致。该改进型LuGre摩擦模型能直观、精确地描述实验平台的摩擦特性,基于该摩擦模型的前馈补偿减小了系统的跟踪误差,提高了系统的定位精度。

Nonlinear friction is one of the main factors that effect both static and dynamic properties of high-precision mechanical servo systems.Considering the different friction characteristics of high-precision experimental platforms at different positions,a modified friction model based on the LuGre model is presented.By taking velocity and position signals as input variables,both static and dynamic parameters of the model are identified using the genetic algorithm.Based on the modified friction model,the experiments and simulations of the friction phenomenon and the friction feed-forward compensation are performed by a high-precision experimental platform and a corresponding simulation servo platform,respectively.Experiments show that the following error after compensation is 1/3 that of original one and the static error of system decreases from 1.4 μm to 0.4 μm with compensation,which is basically consistent with the simulation results without and with compensations.This modified friction model can describe accurately the friction characteristics of the experimental platform,and can be used in the feed-forward compensation to decrease following errors and improve the positioning accuracy for the system.