Nonlinear Position Control of a Scissor-like Kinematics with Elastic Bodies

摘要

Parallel kinematics such as the described machine tools with scissor-like kinematics present as nonlinear mechanical and strongly coupled systems with flexible bodies new challenges in the design and control of machine tools. Linear and independently controlled drives become infeasible due to the parallel setup, machine vibrations become important because lightweight designs are used. Advanced nonlinear and multi-variable control methods show the potential to significantly increase the system performance. Furthermore, flexible multibody system models are a powerful tool for the controller design and evaluation in simulations. In this paper, a rigid as well as a flexible multibody system model of a test machine with scissorlike kinematics is developed. Experimental results with the machine prove that the developed nonlinear flatness-based position controller is able to reduce the trajectory error significantly and that is is possible to achieve an adequate system performance with a nonlinear algorithm in a standard control setup for machine tools. Simulation results with the flexible multibody system further accentuate the need for additional measures such as active vibration damping if flexibilities and process forces are present in the system. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)