Spatial feedforward for over-actuated flexible motion systems

In high-performance motion systems, e.g. waferstages or pick-and-place machines, there is an increasing demand for higher throughput and accuracy. The current design paradigm aims at rigid-body behaviour and leads in an evolutionary way to increasingly heavier systems that require more and more power. This paradigm is rapidly approaching the boundary of its scalability. A new paradigm is to design a lightweight machine and to deal with the resulting flexibilities by over-actuation and over-sensing. Such systems offer freedom to explore new control strategies that exploit the over-actuation and -sensing. This paper presents a spatial feedforward method for over-actuated flexible motions systems, which aims at reducing the vibrations over the complete flexible structure during motion. The proposed method is experimentally validated and compared to the standard input shaping technique.