The Research on the Position Control of the Hydraulic Cylinder Based on the Compound Algorithm of Fuzzy & Feedforward-feedback

This paper aims to research the position control of the hydraulic cylinder controlled by the high-speed on-off valve to realize the precise position control. The strategy combining the pulse width modulation with pulse frequency modulation is proposed to compensate the dead and saturated zones of the high-speed on-off valve, which is on the groundwork of the analysis of the flow characteristic of high-speed on-off valve. A compound algorithm of fuzzy & feedforward-feedback is put forward to realize the precise position control, which can be considered as the duty ratio is given ahead, and the fuzzy algorithm is designed and utilized to deal with the tracking error by adjusting to the frequency and duty ratio of the high-speed on-off valve. The mathematics modeling is analyzed and simulated with the proposed control algorithm using the finite chamber method. The hydraulic loop is established to verify the simulation result with experimental platform. The research finds that the proposed scheme is effective to make the flow linear of high-speed on-off valve and increase the position precision, and the position error can be limited within -0.6 mm  0.6 mm. The application of pulse frequency modulation control method for high-speed on-off valve and the compound algorithm of fuzzy & feedforward-feedback for tracking can significantly improve the position control precision. The design methodology and control algorithm can be applied to other hydraulic system with position control requirement. Copyright © 2014 IFSA Publishing, S. L.