Research On Motion Analysis And Control Of Underwater Manipulator Combined With Screw Theory

With the continuous development of robot technology,the use of robots is becoming more and more extensive.Among them,underwater robots,as a branch of robots,have important significance in studying the motion and control problems in water environment.In this paper,an underwater manipulator designed independently according to the requirements of the subject is studied,and detailed motion and control research is carried out.The first is kinematic analysis.A spin theory is used for kinematic analysis.Since the spin theory only requires the inertial coordinate system and the tool coordinate system,the motion of the rigid body can be described from the whole,so it has a complete and obvious geometric description.In this paper,the positive kinematics and inverse kinematics of 5-DOF underwater manipulators are solved by the theory of spin,and verified by D-H method.Then the Monte Carlo method is used to solve the working space of the underwater manipulator.The robot is then subjected to a kinetic analysis.In this paper,the advantages and disadvantages of the commonly used classical dynamics method are analyzed.The Kane method combined with the spin theory is selected.The dynamic equation of the underwater manipulator is established,and then the dynamics modeling of the underwater manipulator is carried out.Then,based on the dynamics modeling,taking into account the hydrodynamic conditions of the manipulator when it is placed in the water,the Morison formula is used to model and simulate the hydrodynamics,and the manipulator joint torque in the water environment and the air environment The joint torque is compared to analyze the influence of water environment factors on the manipulator.Finally,the trajectory tracking is performed on the underwater manipulator.This paper uses sliding mode control.Firstly,the sliding mode control based on the calculated torque method is used to track the trajectory,and the chattering phenomenon of the algorithm is found to be serious.In order to weaken the chattering phenomenon,the fuzzy gain adaptive sliding mode control is adopted in this paper.This algorithm can not only improve the accuracy of trajectory tracking,but also weaken the chattering phenomenon in sliding mode control.However,there will be an excessive initial impact torque.In order to improve the problem,this paper uses the approaching law fuzzy adaptive adjustment sliding mode control.The algorithm obtains better trajectory tracking effect and improves the problem of excessive initial impact torque.