Motion planning with inverse kinematics and statics of a breeding blanket transporter for robotic remote maintenance of the EU DEMO tokamak

The future demonstration fusion power plant EU DEMO must be maintained remotely in reasonable time to achieve safety as well as economic viability. The largest in-vessel components which will need to be replaced are the breeding blankets (BB’s). Each vacuum vessel sector contains 5 BB segments: two inboard weighing 125 t each and three outboard weighing 180 t each. The BB vertical transporter (BBVT) is a crane-like robotic arm which has been previously designed at a conceptual level to remove and replace the BB segments through the upper port. It has an actuated gripper and 7 joints, which are required for grasping and manipulating the BB segments in 3D space. The BBVT was modeled as a redundant manipulator, and the inverse kinematic problem was solved analytically for cases when one joint position is known. This was applied to generate collision-free waypoints for BB segment handling in the limited confines of the vacuum vessel and upper port while minimizing static loads on the tilting joints.