Active component and control design for torsional mode vibration reduction for a parallel kinematic machine tool structure

The paper reports the holistic development of an active piezo-based component concerning the mechanical design and the control. The active component is used for the reduction of torsional vibrations in a strut of a tripod parallel kinematic machine. By means of this new component the main drawback of the x, y, z-tripod structure can be eliminated. A calculation shows the compliance of the connection between actuators and the adjacent mechanical parts as the most sensitive point of the design. The characteristic values of the piezo actuator were transformed into the active component with the help of design factors. For reducing the structural vibrations a control laws is presented that changes the properties of the electro-mechanical structure, like damping or stiffness. This is possible by a feedback of motion signals, e.g. velocity. The described electro-mechanical model was used for the control design. Experiment results, which are finally presented, show a reduction of structural vibrations.