Research On System Identification And Control Of 6-Dof Cable-suspended Parallel Robot

Cranes are important equipment for marine transportation operation.They are mainly used for the lifting of cargo between ships and the loading of fish missiles.However,under the action of ocean waves,the ship will produce a 6-dof swaying motion,which will bring about the safe operation of cranes huge influence.The cable-suspended parallel robots(CSPR)has the advantages of high load-to-mass ratio and multi-dof movement ability.Based on the background,combined with the advantages of the CSPR,this paper studies the CSPR used at sea.The purpose is to compensate for the swaying motion during the hoisting process and improve the safety of offshore hoisting.The paper first describes the structural characteristics of the CSPR.In the case of upper platform motion,the kinematics model under non-inertial and inertial coordinates was established using vector closure method.Based on the non-inertial model,the relationship between motor speed and platform motion is derived.Based on the modified classical Coulomb viscous friction model,the dynamic model of the motor drive system is established.The Newton Euler method was used to establish the single rigid body dynamic model of the CSPR under inertial system,and the correctness of the mathematical model was verified by Simulink/Adams co-simulation.Aiming at the problem of unknown load inertia parameters,a linearized model of the parameters to be identified for the motor drive system and the moving platform was established,and the least square solution of the linearized model was derived.Aiming at the problem of data acquisition in the process of parameter identification,the Fourier series is used as the excitation signal of the system,and it is proposed that the trajectory should ensure that the cable tension is positive and is inside the working space.Under the condition that the load inertia parameters are known,combined with the control target,the dynamic model of the system is re-derived,and a constrained dynamic control method with expected torque compensation is proposed.This method can achieve the desired control effect when the inertial parameters are known.Aiming at the factors of inertia parameter uncertainty and interference force,the dynamic model of interference separation is derived,and a sliding variable structure dynamic control method is proposed,which can achieve the desired effect when the interference is bounded.Simulink-Adams co-simulation was used to verify the effectiveness of the control method.In the Simulink-Adams co-simulation process,in view of the defect that theCable module in Adams failed to simulate the real cable winding drum,a modeling method was proposed in which the rope is wound on the motor drum and can move with the drum.Aiming at the error-prone problems of the co-simulation cable system,the reasons for the failure are summarized and several possible solutions are proposed.In order to further verify the correctness of the control method and parameter identification method,the CSPR physics experiment platform was built,and its mechanical structure,control system software and hardware were designed.The tracking performance of the system was tested by the control method based on the kinematics model,and the correctness and real-time performance of the kinematics forward and inverse solutions were further verified.