Theoretical And Experimental Research Of Parallel Compound Driving Ship-based Stable Platform

With the rapid development of ocean operation technology,some precision ship-based equipment require more severe requirements for the working environments,which require a stable device to isolate the disturbance caused by wind,wave and current from the ship and external environments,so as to ensure the stable working environment of the precision ship-based equipment.Compared with the series stabilization mechanism,the parallel stabilization mechanism has the advantages of the stronger carrying capacity and the better rigidity.Compared with the general parallel stabilization mechanism,parallel stabilization mechanism with the compound driving unit can divide the disturbances into the high frequency and low frequency,which can effectively improve the precision of stability control.In this paper,a series of parallel compound driving platform is synthesized,and the theoretical analysis and related experimental research of the mechanism are carried out under the condition of non-inertial system.The specific research contents are shown as follows:The analysis of ship motion characteristics and prediction algorithm.Through the mathematical model of wave,the motion law of wave is analyzed,and the motion law of ship is analyzed based on the motion law of wave,and a method of mixing the empirical mode decomposition method(EMD)and support vector regression(SVR)is designed to predict the motion law of ship.Type synthesis of parallel compound drive platform is analyzed.Based on the application requirements,a series of high and low frequency compound driving units are synthesized and their displacement subgroups and equivalent motion pairs are obtained respectively.Based on the displacement manifold theory,a series of parallel compound driving platforms corresponding to the main motion forms of ship are synthesized,and the 3-(RRPRP)RS configuration with the unique equivalent motion forms are selected.Based on the screw theory,the motion forms of the selected compound driving unit and the Dof of the parallel compound driving mechanism are analyzed and verified.The kinematics and dynamics analysis of the 3-(RRPRP)RS parallel compound driving platform under the non-inertial system.Using the screw algebra as the mathematical tool,the position solution,velocity solution and acceleration solution between the upper platform and each link of the mechanism under the linear drive and the rotation drive are analyzed under the condition of non-inertial system,and a step iteration method is proposed to solve the problem of the position solution.and the driving strategy of the mechanism is given,and the driving force(torque)of the linear drive and the rotation drive are analyzed respectively.A numerical example is applied to verify the kinematics and dynamics analysis results of the non-inertial system by using the modeling and simulation of the Adams.The multi-objective size optimization of 3-(RRPRP)RS parallel compound driving platform is analyzed.Under the condition of meeting the requirements of work,the optimization range of the structure size of the mechanism is given,and the speed transmission performance index,the force transmission performance index and the stiffness performance index of the parallel compound drive platform are given respectively.Based on the weighted sum method,a mean weighted sum method is obtained,and the genetic algorithm is combined to achieve this optimization,so the multi-objective optimized structure parameter are obtained.The stability control strategies of 3-(RRPRP)RS parallel compound driving platform are researched.The mechanism structure is imported into the Simulink through the plug-in unit of the SimMechanics Link to carry out the study of the control algorithm,and the RBFFNN-PID controller,the sliding variable structure controller and the ESO based sliding controller are set up.Based on the established controller,and the simulation parameters are given,the simulation model of stable control based on each controller is set up respectively in the Simulink environment,and the simulation results of each control strategy are compared,then the most suitable stable control strategy is selected.The experimental studies of 3-(RRPRP)RS parallel compound driving platform are established.Based on the structural parameters obtained by the multi-objective performance optimization,a prototype of 3-(RRPRP)RS parallel compound driving platform is built.The integrated control cabinet is set up,the man-machine interactive compound drive control interface is designed,and a parallel hybrid drive stable system can be established by combining the existing 6-Dof motion simulator.The motion simulation experiment and the stability control experiment are carried out respectively,so as to provide the technical support for the stability of ship-based equipment.This paper will carry out the theoretical analysis and the experimental research on the the parallel compound driving platform under the non-inertial system.The theoretical content is the stretch of the the traditional screw theory,and it is practical for the experimental research includes the stability control of the parallel compound driving platform,which has the practical significance to provide technical support for the stability of ship-based equipment.