| At present, domestic wheel loader working device basically achieved electro-hydraulicproportional control. However, it is restricted by the actual work environment and complexoperation objects, the work of shoveling material is still manipulated by manipulator controllingthe handle of the shaking arms or the bucket at present. In order to improve the loader operationstability and achieve the loader automatic control, in this article, an improvement was made inthe loader hydraulic system: the high-speed switch valve was used as pilot valve to control themultiple-unit valve, which makes up of a new type digital electro-hydraulic proportional control.Some models and simulations were made for the wheel loader working device hydraulic systemare as follows:The model of the working device hydraulic system was built by the software AMESim. Bythe simulation of the actual working condition, pressure curve of the arm and bucket cylinderand displacement curve of the piston rod can be got. According to the pressure oscillation and thepressure continues to rise at the end of the work cycle phenomena, analysis and put forward theimprovement scheme, then once again simulate the result of the method, verify the feasibility ofthe improvement.To realize the position automatic control of the working device, based on the hydraulicsystem set up the mathematical model of the plural channel valve-piston position controllingsystem, derivation the open-loop and closed-loop transfer function, judge the system’s stability.Though the ordinary PID algorithm and Fuzzy self-adaptation PID parameters method design theposition controller. Lastly, under the Matlab/Simulation environment, by simulation the differentmethod of the control system mathematical model. The results show that the Fuzzyself-adaptation PID parameters method can significantly improve the system controleffectiveness, the system steady-state improved, and has a better adaptive ability. |
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