Research On Passive Loading Control For Multi-dimensional Force Loading System Of Electro-hydraulic Drive Parallel Mechanism

Through predictable semi-physical simulation experiments,the dynamic mechanical environment simulation test of key components under complex load environments can be used to test the mechanical properties and fatigue life of key components under loads close to actual working conditions.The dynamic platform of the electro-hydraulic parallel mechanism multi-dimensional force loading system has multiple degrees of freedom in space,it can simulate different forms of motion in the real working environment,and output generalized force loads in space,which is more comprehensive than the single-degree-of-freedom load simulator.However,the movement of the loaded component itself produces strong posture disturbances to the multi-dimensional force loading system,and excess force is generated in the parallel mechanism with complex dynamics and control characteristics.The interference of excess force severely restricts the dynamic loading performance of the multi-dimensional force loading system of the electro-hydraulic parallel mechanism.Therefore,how to eliminate the interference of excess force and achieve high-frequency response and high-precision dynamic load environment simulation has become the key to the research of passive loading control of the electro-hydraulic parallel mechanism multi-dimensional force loading system.In response to the above problems,this article intends to carry out research works as follow ings:(1)The inverse solution model of the pose,velocity and acceleration of the electro-hydraulic parallel mechanism multi-dimensional force loading system is established based on coordinate transformation and vector analysis methods,and the positive solution model is established based on the Newton-Raphson iterative algorithm.The system dynamics model is established based on Newton-Euler method and Lagrangian method,which lays the foundation for the research of system dynamic characteristics.(2)The hydraulic power element model is established based on the electro-hydraulic servo theory,combined with the dynamic model,the overall model of the electro-hydraulic parallel mechanism multi-dimensional force loading system is established.On this basis,the dynamic characteristics of the multi-dimensional force loading system are studied,the mechanism of excess force generation is analyzed,then the theoretical basis for the design of the passive loading controller of the multi-dimensional force loading system is provided.(3)Research the structure of the inverse model observer to suppress the pose disturbance,adopt the dominant pole configuration method to design the filter of the inverse model observer structure,and optimize the filter parameters in combination with robust stability conditions.Considering the load stiffness of the flexible load mapped to each joint space,the modal space is established using the theory of vibration mechanics,and the modal inverse model observer structure is constructed.(4)Develop an experimental plan for passive loading of the electro-hydraulic parallel mechanism multi-dimensional force loading system based on rapid prototyping control,conduct an experimental analysis on the characteristics of the passive loading of the multi-dimensional force loading system,then the proposed modal inverse model observer structure and the effectiveness of the improved passive loading performance of the multi-dimensional force loading system is verified through experiments.