Abstract: Based on the proportional flow valve as hydraulic motor flow control element and the multiturn rotary encoder as motor speed feedback link, the closed-loop control system of electro-hydraulic proportional valve controlled motor speed was constituted.For the realization of stability control for the speed of pulling hose, PID control strategy is proposed to optimize the design for control system.Focus on the problems of speed stability, a proportional valve controlled motor hydraulic system mathematical model was established and the software package SIMULINK in the MATLAB software was used to simulated the system dynamic.The results show that the system using control strategy has faster response, less overshoot than the original system, and it has overcome the speed instability during the charge process, which can meet the control requirements.

Key words: Underground middle-deep blasting hole, Explosive loading truck, Closed-loop control, PID Control, Simulation