Structure Design And Research On Master-Slave Control Strategy Of Underwater Manipulator

Nowadays,nuclear energy has accounted for a growing share of energy in many countries,and the nuclear safety problem is also promoted to a new height. Some tasks in nuclear power plant such as device detection, pipeline maintenance, underwater welding are solved by using advanced robot technology,that has become a hot topic in the development of industrial robots. Especially, the environment, the highly radioactive’s nuclear reactors and spent fuel pool,the underwater equipment, increses the risk of staff to detect,leak and welding. Under the circumstances, underwater master-slave manipulator is the proper choice to deal with these issues.In this paper,according to the development status of master-slave robot and underwater manipulator, a master-slave underwater manipulator is designed with calls for underwater detection and welding for small and medium nuclear power plant reactor. And the kinematics,master-slave scale mapping relation, stiffness, the motion error of endpoint and the single joint control system is analyzed. The research on the simulation of two-joint master-slave manipulators is developed through the real-time simulation system dsPACE,which provides the basis for the master-slave manipulator’s control strategy.Based on the underwater working environment, the structure design which contains a six-degree-of -freedom master manipulator and a similar slave manipulator is carried out.And the master-slave manipulator is studied from the aspects of configuration, overall dimensions, joint angle, joint structure and key parts, as well as is created virtual modeling through 3D modeling software.The kinematics and dynamics of slave manipulator is established based on structural parameter. And the kinematics is solved by D-H method, using MATLAB toolbox for kinematic modeling and simulation research. The results indicate that the forward and inverse kinematics equation is correct and structural design is reasonable. Then, the simplified model for slave arm is built by Lagrange method so as to validate the feasibility of joint actuators.Calculating manipulator workspace and comparing the effect extend of different mapping approaches and coefficients, the master-slave scale mapping relation is worked out, which benefit the master-slave control.During the movements of the master-slave manipulators, the stress, deformation and modal using model analysis theory are obtained in ANSYS WORKBENCH. The simulation resolts show that performance of the master meets requirements,while the slave is relatively low, then the weaker joint arm is optimized. The repeat accuracy ability of the end-position is outlined by differentials, and calculated in MATLAB, so the datas from the error factors such as length, Angle, motion variable are worked out, and the total errors prove that the slave’s accuracy meet design requirements.This paper introduces motion control system,hardware platform, the working flow of underwater manipulator and so on. Because underwater operation task and environment are changeable, the fuzzy controller is applied to the position control of a single joint based on mathematical model and the simulation indicates that the fuzzy controller is better than the traditional PID control. Finally, the master-slave follow movement is executed experimentally in dSPACE test platform using the two-joint of master-slave manipulators, the results prove the validity of control algorithm as well as the rationality of structure designing.