Research On Nuclear Underwater Mobile Robot Control System

Control rod guide tube split pin is an important component of upper internals in nuclear station reactor.Due to the complex work environment of high temperature,high pressure,strong neutron irradiation,thermal load and vibration load,experience feedback showed primary water stress corrosion cracking may occur in split pins with the nuclear unit operation hours growing.During a overhaul,upper internals are stored in a water pool as a whole,and control rod guide tube split pins can be inspected by plugging ultrasonic probes into split pins below the upper internal assembly.This paper developed a underwater mobile robot control system based on vision positioning on the project of "Control rod guide tube in-service inspection technology research" undertaken by CGN Inspection Technology Co,.Ltd.,The main research contents are as follows:Firstly,this paper completed the mechanical structure design of the underwater mobile robot composed of a mobile chassis and a high accuracy positioning platform,fulfilled the hardware design of the control system based on CAN bus,and proposed a unique radiation reinforcement strategy and underwater sealing scheme;Secondly,this paper established and analyzed the kinematics model of the motion chassis and the positioning platform,which showed the several motion modes and turning radius of the mobile robot.Kinematics experiment was also performed,which agreed with the theoretical analysis.Finally,this paper studied underwater mobile robot control based on vision positioning,designed the software and motor servo system.The whole system was tested on mockup both onshore and underwater,and all functions of robot were passed.The sub-millimeter positioning of ultrasonic probe was achieved and ultrasonic probe's plug into control rod guide tube split pin was successful,which verified the effectiveness of the software and hardware of the control system.