Research On Design And Kinematic Control Of Parallel Manipulator For Underwater Vehicle

With the continuous consumption of energy in the world,nuclear energy is playing an increasingly important role as a new generation of clean energy,and the safety of nuclear power plants has also attracted everyone’s attention.Therefore,relevant nuclear facilities,such as nuclear power plant pools,need to be inspected regularly,cleanup and repair operations.Due to the limited space of the nuclear power plant pool,the volume of the underwater robot is relatively large.Therefore,when the small underwater robot is used for operation,the center of mass,the center of buoyancy,and the changes in the hydrodynamic force caused by the movement of the robot arm It may cause greater disturbance to the dynamic stability of the robot body.In response to these problems,this paper designs a parallel manipulator arm that can be mounted on the body of a nuclear power plant underwater operation robot.It aims to improve the overall motion stability and operation accuracy of the underwater manipulator arm and the robot,and reduce the impact of the manipulator on the robot body.In order to meet the needs of underwater operation tasks,the configuration of the manipulator was determined and the kinematic model was derived,and the structural parameters were optimized according to the design requirements;combined with the theory of fluid-solid coupling,based on Fluent,the parallel manipulator components were in the working position The underwater adaptive drag reduction optimization design is carried out;in order to verify the stability of the mechanism underwater,the wet modal parameters of the parallel manipulator under water are simulated and calculated.In order to establish a comprehensive hydrodynamic model of the parallel arm,based on the principle of virtual displacement,the rigid body dynamic model of the parallel configuration manipulator was derived and the trajectory parameter relationship of each component was obtained.The three types of hydrodynamic interference were analyzed and deduced based on Adams performed a simulation analysis on the theoretical model.In order to realize the decoupling planning and stable operation of the parallel manipulator under water,the fifth-order polynomial planning rate and the fifth-order NURBS planning rate are introduced underwater,and the trajectory displacement,velocity and acceleration are tested by simulation and the latter is verified.Superiority in underwater applications;in order to compensate for the disturbances introduced by unknown models and environmental errors,a computational torque control strategy based on PID feedforward and a neural network robust control strategy based on PID feedforward are designed,and the controller is controlled through simulation experiments.The tracking effect and accuracy of the controller were simulated to verify the reliability of the controller.In order to verify the theoretical analysis results,a parallel underwater manipulator prototype was designed,the control system hardware architecture of the manipulator was built,and a software system for human-computer interaction was developed based on QT.The robot arm motion control experiment was carried out in the pool,and the ATI six-dimensional force sensor was used to collect data.The disturbance of the parallel robot arm to the base during the movement was analyzed,the accuracy tracking effect and stability of the robot arm under the action of the controller was verified.