Abstract:In researches of friction compensation in the servo system, aimed at some disadvantages of the friction models widely used at present, for example, the Dahl model could not describe the complete friction phenomenon, the LuGre model is too complex, there are so many parameters and application in practice is unstable, and etc., the causes of these problems were analyzed and discussed. Considered together with the actual motion characteristics of the servo system, a modified friction model was proposed, by introducing the stribeck function and overall friction term in the model. Besides, through the simulation experiment,the analysis results show that the modified model is effective, in three aspects of the stribeck effect, stickslip motion of servo system and limit cycle phenomenon.