Iterative Learning Control of a Direct Driven Spatial Parallel Manipulator

Iterative learning control (ILC) is proposed in this paper for the enhancement of tracking accuracy of a parallel direct driven manipulator. It is shown by means of a simulation study and by experimental results, that linear ILC is appropriate for application to the considered high nonlinear and coupled system. For this purpose, it is necessary to map the dynamics of the closed-loop feedback controlled system. This is achieved in a first approach by the frequency response and in a second one by the difference equation of a linear time invariant plant. The results of both algorithms are discussed