Flatness-based control of parallel kinematics using multibody systems - simulation and experimental results

The development of new machine tools such as parallel and hybrid kinematics leads to new challenges in the design and control of such machines in comparison to conventional ones. Parallel kinematics exhibit inherently nonlinear dynamics over the whole workspace, machine vibrations become important as a lightweight design is used and independently controlled drives become infeasible due to the parallel setup. Advanced nonlinear position control methods such as the presented flatness-based design show the potential to significantly increase the machine tool performance. In this paper simulation results are presented for a high performance machine tool and nonlinear flatness-based position control. Experimental measurements and simulation results for a test machine proof that with the nonlinear controller the trajectory error can be reduced considerably compared to the standard linear controller.