Flexible multibody dynamics and control of a novel hydraulically driven hybrid redundant robot machine

This paper studies the dynamics and control of a hybrid parallel-serial mobile robot designed for the assembly and maintenance of International Thermonuclear Experimental Reactor (ITER) under the effect of machining forces using floating frame of reference method FFRF. The finite element (FE) models of flexible rods are obtained by a Lagrangian formulation, and the Craig-Bampton modal vectors are extracted from these FE models. The assembling of component models using the constrained Lagrange´s equations and the Lagrange multiplier method for the six closed loop mechanisms leads to a system dynamic model. Subsequently, the reaction forces between the parallel part and the serial part were used to study the dynamics of the serial robot. A hydraulic control system of a linearized PID is implemented independently to control each hydraulic cylinder of the robot based on position predictions. Finally, simulated results that demonstrate the robot behavior are presented.