Research On Stability Control Of Parallel Three-degrees-of-freedom Ship-borne Stabilization Platform

The ship produces six-degrees-of-freedom motions of heave,sway;surge,roll,yaw,pitch under the influence of the marine environment,and these undesired motions seriously affect the safe operation of various ship-borne equipment.Generally,the three degrees of freedom motions of the ship's sway,surge and yaw can be compensated by dynamic positioning system,the heave,roll,and pitch motions can be compensated by the parallel three-degree-of-free(3-DOF)ship-borne stabilization platform,so that the support surface on the parallel 3-DOF ship-borne stabilization platform remains stable relative to the inertial space,thereby isolates the effects of ship motions on the ship-borne equipment,and ensuring the ship-borne equipment on the platform is working normally and smoothly.However,there are problems such as dynamic uncertainties and unknown time-varying external disturbances on the ship-borne stabilization platforms,making it difficult to stabilize,therefore,carrying out the research on the stability control of ship-borne stabilization platform has important theoretical significance and application value.In this paper,the 3-UPS parallel 3-DOF ship-borne stabilization platform is designed first,and its degrees of freedom and kinematics are analyzed.Then,aiming at the stabilization control problem of parallel 3-DOF ship-borne stabilization platform under dynamic uncertainties and unknown time-varying external disturbances,the principle of active disturbance rejection control(ADRC)is used to construct an extended state observer(ESO)to online estimate the total disturbances resulted from system dynamic uncertainties and unknown external disturbances.The estimates of the total disturbances is fed forward to the control inputs to compensate the total disturbances,and the ship-borne stabilization platform ADRC stability control law is designed so as to achieve stability control of the platform.The results of MATLAB simulation experiments verify the effectiveness of the designed stability control law of the ship-borne stabilization platform,and superior to the PID control law.Further,an adaptive extended state observer(AESO)is designed by combining adaptive technology with auto disturbance rejection control,to improve the estimation accuracy for the state and total disturbance of ship-borne stabilization platform,and the ship-borne stabilization platform ADRC based on AESO stability control law is designed to improve the stability control accuracy of ship-borne stabilization platform.The results of MATLAB simulation experiments verify the effectiveness of the designed stability control law based on AESO of the ship-borne stabilization platform,and robustness to total disturbance.At last,the Adams software and the MATLAB software are used to build a 3-DOF ship-borne stabilization platform stability control co-simulation experiment system,to carry out co-simulation experiment on the designed ship-borne stabilization platform stability control law.The simulation results intuitively show that the designed ship-borne stabilization platform stability control law can effectively realize the stability control of the 3-UPS parallel 3-DOF ship-borne stabilization platform.