Study On Design And Control Strategy Of An Electro-hydraulic Synchronous Motion System For Lifting Of A Floating Raft

Floating raft, as an effective vibration isolation and noise reduction device, is developing towards the direction of large-scale and integrated now. In installation process, the vertical height of raft frame needs to be adjusted within a certain range in order to install the elastic support between the shell and the raft frame. With the increasing size and weight of floating raft and diversity of equipment installed on raft shelves and equipment's layout ways, higher requirements are raised about accuracy and adaptability of synchronous lifting raft frame. In spite of a typical form for floating raft adjustment vertically, synchronous lifting cylinders with an advantage of fast response and high control accuracy, which is adapted to systems that need high performance for synchronization, four cylinders can't maintain the desired synchronous movement and it is a challenge for improving system's synchronous performance as a result of uneven distribution of raft weight and difference bearing of hydraulic cylinders between bow and stern. This paper focuses on the floating raft system for entrance, conducts a mathematical modeling study of valve-controlled cylinder position servo system and does simulation and experimental verification about synchronization control strategy.Firstly, the composition and principles of the floating raft system was introduced and the overall scheme of the hydraulic drive system was given. Selection and design were done to the key elements of hydraulic elements. A hydraulic system char was drew. Simultaneously, the selection of the controller was described and a display control system flow chart was developed.Secondly, a mathematical model of the valve controlled cylinder electro-hydraulic position servo system was presented and simplified with the actual model. By reviewing the actual engineering data, the system simulation parameters was determined and stability analyzed. Based on the model, various control algorithms were applied to the single system. By means of combining fuzzy inference with traditional PID control, the control precision of single cylinder was improved. On the basis of it, a simple synchronization control strategy named ‘cross-coupled fuzzy PID' was developed by employing the cross-coupling PI synchronization control structure with fuzzy inference engine. Compared with the controller based on the traditional ‘equivalent' synchronization control strategy, the control strategy proposed in this paper could reduce the synchronization error between the hydraulic cylinder significantly and improve the synchronization performance of system effectively.Finally, build physical platform based on the designed hydraulic control system, transplant control algorithm to the controller and do joint debugging on floating raft system for entrance. Experimental data shows that the designed control algorithm could reduce synchronization error caused by uneven loading during lifting hydraulic cylinders effectively and the control system has a good performance in fast tracking and synchronization control accuracy. The entire system meets the technical requirements of floating raft system for entrance.