Research On Dynamic Model And Optimization Of Electro-hydraulic 3-UPS/S Parallel Stabilized Platform

In the process of navigation, ship’s attitude is constantly changing because of the influences of storms or other environmental conditions, which is a threat for the safety of the equipments and staffs. The development and use of the stabilized platform, whose main task is isolating ship’s disturbance, greatly improves the safety factor of equipments and staffs. This thesis mainly focuses on the electro-hydraulic 3-UPS/S parallel stabilized platform which adjusts the horizontal attitude. Then the stabilized tracking experiment system of the electro-hydraulic parallel stabilized platform is built, and some tests about the orientation-workspace, model and stable tracking performance are carried out. The main research contents are as follows.The kinematics of the parallel stabilized platform is analyzed and the size is optimized. According to the design requirement of the platform for the orientation-workspace, the effective attitude workspace(EAWS) is proposed and the volume of EAWS is used as the index for measuring platform’s ability to circumvent the singularities. In order to make sure that the transmission performances of velocities and forces of each driving branch are relatively better, kinematics distribution index is put forward. The size of parallel stabilized platform is optimized based on maximum the volume of EAWS and optimal kinematics distribution index.The multi-energy domain global dynamic model of the electro-hydraulic 3-UPS/S parallel stabilized platform system is established. Based on the bond graph, the screw bond graph is introduced and studied for the spatial parallel mechanism. It has the characteristic of screw theory which is simple and intuitive to describe the spatial mechanism and bond graph which is unified and standard to build the multi-energy domain model. Dynamic models of the mechanism and hydraulic drive subsystem are built by screw bond graph and traditional bond graph, respectively. And then the global dynamic model of the system is obtained. Based on this global model, the dynamics is solved and verified.Based on the global dynamic model, the inertia and friction parameters of the system are identified via the experiments. The identification model for the inertia parameters is obtained by screw equivalence principle and virtual work principle, and the exciting trajectory is designed by Fourier series which is modified by the quintic polynomial and optimized. The intrinsic friction parameters are separated form the friction model, the identification model for the friction parameters is built, and the exciting trajectories are planned. The identification results are obtained by the experiments, and verified through an arbitrary trajectory.The global simulation model of the parallel stabilized platform is built by 20-sim based on the bond graph. Two stability control strategies which are position closed-loop and double closed-loop with speed feedforward are simulated to get the better one which makes the platform have higher tracking accuracy. The attitude workspace and stable tracking performance of platform are verified and tested by the experimental system. Furthermore, the real-time tracking performance of the platform is tested based on the wireless communication building the connection between the mobile device and the platform.