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Nowadays, feed axes are often equipped with multiple parallel-acting actuators in order to increase the dynamics of the machine tool. Also, additional actuators for active damping are widely used. Normally, the drives or actuators are controlled independently without consideration for the impact on each other. In contrast, by using the modal space control, the system can be decoupled and the modal control loops can be adjusted independently. This control approach is particularly suitable for motion systems, such as machine tools, which have more drives or actuators than degrees of freedom of movement. This paper deals with the pre-investigation of the modal-based vibration control for machine tools with additional actuators. The object of investigation is an elastic system with a movable saddle. The modal-based control is compared with a local control approach. The results obtained experimentally on the test rig are presented. The modal control is superior since, with the modal approach, each control loop corresponds to a specific vibration mode, and the control law for this loop is designed to provide the desired performance of the control system at the corresponding resonance frequency. The parameterisation of the control loops is simplified by modal control, since the modes can be controlled independently.

Gantry stages, which consist of two parallel acting servo drives, are commonly used in machine tools. One drawback of this concept is the crosstalk between both drives due to the structural coupling that can cause stability issues and therefore limits the bandwidth of the position control. This paper deals with the development of compliant joints to solve the coupling between the drives. When compared to solutions containing bearings, the advantages of such flexible elements are low friction and the absence of backlash. To adjust the properties of the joints, packages of spring-steel-sheets are used as compliant links. One design aspect of the flexible joints is a low stiffness relating to the rotation around one specific axis, but a high stiffness relating to the other degrees of freedom. With this method, the dynamic behaviour of the gantry stage is modified and the bandwidth of the controllers can be increased. Additionally, by releasing the mechanical coupling of the drives, the reaction forces the actuators have to provide can be reduced. Both systems with flexible and with rigid connecting elements, are analysed by measured frequency response functions.

Kurzfassung Mit zunehmender Flexibilisierung der Fertigung und kleineren Serien gewinnt das thermische Verhalten von Werkzeugmaschinen signifikanten Einfluss auf die erreichbare Werkstückqualität. Im SFB/Transregio 96 werden Lösungen zur Beherrschung des thermischen Maschinenverhaltens entwickelt. Das Teilprojekt C06 stellt mit der selektiven Thermografie ein Messverfahren zur Verfügung, mit dem die experimentelle Analyse des thermischen Maschinenverhaltens vereinfacht und verbessert wird.