Analysis and Compensation for Friction in Valve-controlled Asymmetric Cylinder System

The research object was a valve-controlled asymmetric cylinder system which was widely used in electro-hydraulic servo systems.The friction of the system was measured,and an online friction observer was designed.According to the structure invariance principle,a dynamic friction compensation method was proposed to compensate the system friction.The experimental results show that compared with PID control strategy,the dynamic friction compensation method improves the positional accuracy of the valve-controlled hydraulic system.