Research On Optimization Design?Calibration And Predictive Control Of Stewart Shipborne Stabilized Platform

Under the influence of sea waves and other marine environment,a ship traveling at sea will have a six-dimensional motion,which will seriously affect the launching accuracy of shipborne weapons,the work and life of shipborne personnel.The ship stabilized platform can actively compensate the disturbance of the ship,so as to ensure the stability relative to the inertial coordinate system,improve the working accuracy of the shipborne equipment safety.The Stewart hydraulic shipborne stabilized platform is taken as the research object in this paper,the motion analysis and prediction of the ship,Stewart kinematic solution,mechanism parameters optimization design,kinematic calibration and control method of the shipborne stabilized platform are studied respectively.The specific research contents are as follows:The ship motion analysis and very short-term motion prediction.The frequency domain method is adopted to simulate the ship motion.ITTC double parameters of wave spectrum is used to calculate the wave motion.The amplitude response operator RAO(Response Rmplitude Operator)of the ship is simulated by ANSYS AQWA,Then,the six-dimensional motion of different ships under different sea conditions are got through wave motion and RAO.The AR model is used to predict the ship motion,and the accuracy of the prediction algorithm is verified by numerical examples.The Stewart platform kinematics analysis.The forward and inverse kinematics of Stewart platform are analyzed,the method of step-adjusting Newton is applyed to forward kinematics of Stewart platform.Then,the initial values of step-matrix and geometric parameter are taken as variables,the iterative steps of forward kinematics is used as objective,by genetic algorithm,to get the optimal values.Numerical example is given to verify the convergence and rapidity analysis of the method,and the total orientation workspace of Stewart stable platform is solved to compensate the six-dimensional disturbance of the ship.The multi-objective optimization design of Stewart.According to the six-dimensional motion of the ship,the total orientation workspace of Stewart platform is set up.Aiming at the problem that the numerical method is low accuracy and low efficiency.The algebraic method cannot get extreme value when solving the maximal leg lengths of Stewart platform with desired total orientation workspace.A hybrid method where the numerical method is used for orientation variables and the algebraic method is used for translation variables is proposed,which improves the precision and efficiency.Taking the total orientation workspace as the constraint and taking the physical size and kinematic performance indexes as the optimization objectives,NSGAII algorithm is used to optimize the mechanism parameter.The kinematic calibration of Stewart mechanism.The kinematic error model of Stewart platform is established.The identification Jacobian matrix containing both displacement and attitude is dimensionless,the measurement configurations are selected according to the observability index.Calibration simulation is carried out by selecting the measurement configurations and identification parameters and error compensation.The calibration experiment of Stewart platform is carried out based on the measurement configurations obtained by the normalized identification Jacobian matrix.Model predictive control of stabilized platform.The AR prediction of ship motion,one part is used to compensate the time delay of HDU(Hydraulic Drive Unit),and the other part is used as the reference trajectory of the rolling optimization of MPC(Prediction Model Predictive),a model predictive control based on ship motion prediction(MPMPC)is proposed.The mathematical model of hydraulic drive unit is established,the model parameters and system delay parameters are identified through experiment.The simulation and experiment of HDU based on MPMPC proves that MPMPC control has higher tracking precision.Based on Stewart platform and 2DOF motion simulation platform,a ship stabilization compensation system is built.The simulation and experiment of Stewart platform based on MPMPC are carried out,and it is verified that the control effect based on MPMPC has smaller residual motion than traditional MPC.