Research On Kinematics Control Of Underwater Rope-driven Manipulator With High Decree Of Redundancy

With the advancement of human science and technology,the demand for the exploration of the ocean environment is growing.However,due to the harsh prerequisite such as frosty and high pressure in the ocean environment,the underwater robotic arms are generally used to assist or replace humans in underwater sampling,connection,deployment,detection,maintenance,salvage and other tasks.Though the traditional underwater manipulator has high working efficiency,maintenance of control accuracy and stability,it is often impossible to achieve the simultaneous body control with flexibility and position control of end-effecter due to the limitation on the numbers of degrees of freedom.With a large number of degrees of freedom,the cable-driven hyper-redundancy manipulator has the superiority in the obstacle avoidance and strong load capacity.Though domestic and foreign scientific research institutions have carried out some researches on the cable-driven hyper-redundancy manipulator,it is still in the exploration stage in the lab,and few are studies for the underwater environments.Therefore,a cable-driven hyper-redundancy manipulator for the underwater environments is designed in this thesis,where the kinematics are derived in detail,the complex mapping relationship among driving space,joint space and working space are established,and a motion controller is designed based on the kinematics model.The real platform experiment with 5-joint manipulator prototype is carried out and verifies the rationality of the structural design,the correctness of the forward and inverse kinematics solution and the effectiveness of the controller.This thesis is divided into five chapters,which are briefly described as follows:Chapter 1 expounds the research background and significance of the cable-driven hyper-redundancy manipulator,and introduces the research status.Based on the operational requirements of underwater space-constrained environment and the characteristics of flexible obstacle avoidance and strong load capacity of this kind of manipulation,the concept of using this kind of manipulator for underwater environments is proposed,and the difficulty of motion control in complex underwater environments is summarized.Finally,the main research contents of this thesis are described.Chapter 2 considers the mechanical load capacity,lightweight design,sealing,material selection and other issues,and conducts the structural design of the cable-driven hyper-redundancy manipulator,where the joint unit parts,joint structure and compression resistance are applied,the structure and other parts were optimized,and the layout of the drive cable,the selection of the number,and the location of the drive unit modules are analyzed.Finally,with regard to the control requirements,the appropriate motor and its reducer,motor driver,data acquisition system,magnetic grid displacement sensor and other devices are selected.Chapter 3 derives the kinematics model of the driving space-joint space-operation space for the cable-driven hyper-redundancy manipulator.The forward and inverse kinematic relations between the driving space and the joint space are solved by the geometric relationship between the joints and the coordinate transformation equation,and the forward kinematics model of joint space-operating space is established by the coordinate transformation equation.For the complex inverse kinematics,the motion process is decomposed according to the general application scene and motion mode of the manipulator,and the geometric relationship and space vector coordinate transformation matrix is used to solve the inverse kinematics of different motion stages.Chapter 4 develops the precise motion controller of the cable-driven hyper-redundancy manipulator,where a PI controller is designed based on the kinematics model,and its effectiveness is verified by experiments.By means of the forward kinematics control of the 5-joint manipulator prototype,the end trajectory control based on inverse kinematics,the end trajectory control with obstacle avoidance,and the underwater grabbing experiment,the rationality of the structure,the correctness of the kinematics solution and the effectiveness of the motion controller are verified.Chapter 5 summarizes the main work and research conclusions of this thesis,and prospects the future research on the cable-driven hyper-redundancy manipulator.