Theoretical and Experimental Study on Hydraulic Servo Position Control System with Generalization Pulse Code Modulation Control

In this paper, the hydraulic servo position control system with generalization pulse code modulation (GPCM) control is studied. The flow rate of the GPCM control system is controlled by a series of N solenoid on-off valves which are calibrated having different flow, and are activated by N bits binary pulse codes. In traditional PCM control, the flow rates of valves are arranged increasing accord with binary, so the minimal and maximum flow rates are limited, then precision of the system are limited. The flow rates of valves are set according to special modulation code in GPCM (generalized pulse code modulation), and response speed and precision of the system are improved. The method how to determine minimum-opening area of valves is worked out by analyzing stability of the GPCM system by nonlinear theory. The experiment results show that the GPCM control system can satisfy requirements of response speed and precision of hydraulic system.