Rest-to-rest motion of a two-link robot with a flexible forearm

We consider the problem of finding the torque commands that provide rest-to-rest motion in a given time for the FLEXARM, a two-link planar manipulator with a flexible forearm and nonlinear dynamics. The basic idea is to design a set of two outputs with respect to which the system has no zero dynamics. Planning smooth interpolating trajectories for these outputs imposes a unique rest-to-rest motion to the whole robot, with bounded link deformations. The nominal rest-to-rest torque is obtained by standard inverse dynamics computation. In the multi-input nonlinear case, this approach requires in general the use of a dynamic linearizing extension. Numerical results are presented and possible extensions discussed.