Conceptual design of an in-vessel inspection robotic system for Tokamak environment

An in-vessel inspection robotic system has been conceptualized for operation inside a tokamak vessel. The robotic system is envisaged to comprise of a robotic arm, end-effector, microcontroller and wireless communication system. The end-effector is envisaged to be a special purpose camera for in-situ inspection between plasma shots. The three-link robotic arm, designed for ITER-like environment, has 4 revolute joints- 3 providing manipulation in poloidal plane and the fourth one providing limited movement in adjacent toroidal planes. This paper provides the conceptual design of the system along with kinematic analysis of robotic arm. Solutions have been derived for forward and inverse kinematic models and the Jacobian matrix for the robotic arm linkage. In forward kinematic model, given a set of joint-link parameters, the position and orientation of end-effector are determined with respect to a reference frame. In inverse kinematic model, given the specified position and orientation of end-effector with respect to a reference frame, a set of joint variables are derived that would bring the end-effector into the required posture. Using Jacobian matrix, the relation between the end-effector velocity and the joint velocity of a manipulator is obtained i.e. given the individual joint velocity; the end-effector velocity is obtained. A CAD model has been generated using CATIA to simulate the kinematic model and carry out computational stress analysis. (author)