Research On Hydraulic System Of The Multi-DOF Hydraulic Arm

Pneumatic ship unloader is one of the main ship unloading equipment on thebulk terminal, the multiple degree of freedom（multi-DOF）hydraulic arm is thesupporting device for nozzle of the pneumatic ship unloader, the performance of themulti-DOF hydraulic arm have a significant influence on the efficiency of thepneumatic ship unloader. The hydraulic system of multi-DOF hydraulic arm isstudied; this thesis conducts the research on the following issues:Firstly, due to the defects of hydraulic system of the multi-DOF hydraulic arm,the movement of the arm is instable, and the energy loss is serious. The workingprinciple and the performance requirements of the hydraulic system of thehydraulic arm are analyzed.Secondly, based on the working condition of the hydraulic arm, the loadsensing system was applied to the hydraulic system of the hydraulic arm; a newhydraulic system of the multi-DOF hydraulic arm is designed.Finally, the Bond graph model of the load sensing system is established. Thestability and time-domain analysis are studied by using the control theory and theMATLAB software. And the effect of structural parameter of components on thedynamic feature of the hydraulic system is studied by using AMESim software.The simulation results show that, by selecting the appropriate gain factor, thehydraulic system with load sensing system may obtain good stability and highcontrol accuracy as well as other time-domain performance. By selecting theappropriate load feedback tubing and the spring stiffness of the sensitive valve, thedynamic performance of the hydraulic system could be improved. The results willbe useful for understanding, using and designing the hydraulic system ofmulti-DOF hydraulic arm.