Screw-based dynamics of a serial/parallel flexible manipulator for DEMO blanket remote handling

Remote handling of heavy in-vessel components inside nuclear fusion reactors requires the use of large robotic mechanisms, whose numerical analysis is highly complex. As a matter of fact, these robots are subject to large deformations, either induced by the geometric configuration of their mechanical structure or by the heavy payloads they usually transport. This work was motivated by the need of deriving physical-based predictive models able to simulate the mechanical behavior of such large robotic mechanisms, while performing dynamic tasks. The method formulates the dynamics of robotic manipulators on a Lie group, and uses a finite element procedure to discretize the flexible bodies. The method is applied to a complex mechanism, the serial/parallel flexible manipulator which has been recently selected for DEMO blanket remote handling. The case studies investigated in this paper involve the simulations of this manipulator while handling the inboard and outboard blanket segments according to the sequence of maneuvers planned for their removal processes from the vessel. The results show that such dynamic simulations could give useful information for design, analysis and control of remote handling equipment. The generality of the method makes this approach prone to be easily used in simulating the dynamics of other flexible manipulators for remote handling of large in-vessel components inside nuclear fusion reactors.