Control design and experimental validation of an adaptive spindle support for enhanced cutting processes

In this paper we present an adaptive spindle support that can be used for additional fine positioning movements during machining operations. This is achieved by an overlaid piezo-based hexapod-kinematic structure that is mounted between the machine structure and the motor spindle. Here we present the analysis of the spindle support regarding control aspects. The basis is a finite-element-model that was used to determine a state space model of the component. The model was validated by an experimental modal analysis of the structure. Knowing the modal characteristics allows an analysis of the mechanical couplings between the different axes of the spindle support which accordingly enables the design of a controller considering mechanical couplings. For experimental validation the controller was implemented into a rapid prototyping system. The presented results show that during cutting operations the spindle can be moved with high precision within a wide range of frequencies.