Research On Modular Small Underwater Manipulator

Underwater robot is an indispensable and important device for exploring the ocean and developing ocean resources.Underwater manipulator is an important actuator of underwater robot,which can complete various complicated underwater tasks and improve the work efficiency of underwater robot.A modular small underwater manipulator is designed based on the "modular" theory in this thesis.The manipulator is composed of unified modular joints,which can form different configurations by increasing or decreasing the number of modular joints or changing the connection mode between modules.The manipulator can also adapt to different working conditions,which has practical significance in improving the applicability of the underwater robot to different working environments.An appropriate modular topology structure is selected and the connection mode between modules is analyzed according to the functional requirements of modular underwater manipulator.The coding rules were formulated to represent all the configurations of the manipulator that could be constituted by binary codes,and the invalid configurations were eliminated.The joint module that can realize modular function is designed,and the strength of the key parts and the whole manipulator is checked to ensure that the manipulator has enough strength.The effective configuration of the modular underwater manipulator is analyzed based on D-H parameter method,and its workspace is simulated by MATLAB.The applicable working conditions of different configurations of the manipulator were analyzed according to the results.Taking one of the configurations of the manipulator as an example,the trajectory planning is carried out to lay a foundation for the following dynamics analysis and control system construction.The dynamic equation of the manipulator is deduced based on the Lagrange method.Taking the manipulator of one configuration as an example,the influence of water resistance on the motion of the modular underwater manipulator was analyzed by Morrison equation.The dynamics simulation of the manipulator was carried out by ADAMS,and the influence of water resistance and the change of joint torque of the manipulator were analyzed.The robotic arm control system is established based on ROS,the physical prototype of modular underwater manipulator is made,the experimental platform is built to carry out the motion control experiment on the manipulator prototype of different configurations,and the working ability of the modular underwater manipulator of different configurations was analyzed.Through the analysis of simulation and experimental research results,it can be seen that modular underwater manipulator can form a variety of effective configurations,and all of them can complete the given underwater task,which can effectively solve the problem of poor universality of underwater manipulator,and improve the adaptability of underwater robot to different working conditions.