Ibis paper presents active vibration control of a hydrostatically supported, flexible beam. The objective is to show the capability of active hydrostatic bearings, where the flow rate is controlled with a fast dynamic servo valve. Consequently the damping as well as the stiffness behaviour of the supported structure should be improved. First the damping behaviour is increased by using acceleration feedback in combination with the modem, robust control concept -synthesis. It enables to overcome undesirable properties of the mechatronic system as, weakly damped, low frequency flexible modes, phase lag, slight nonlinearities or non-collocation. To increase the stiffness of the bearings the oil gap is used as control variable and controlled to constant with PI-control. Finally, the obtained results are compared with the state-of-the-art technology of hydrostatic bearings.
This paper presents the investigation results and an implementation example of robust µ-controllers for axes of milling machines. The challenge to transfer modern control methods from research to industrial application is tackled by showing necessary steps performed for the implementation. Constraints inherently given by a real machine control unit are considered and treated. Two test rigs, a two-massoscillator driven by a synchronous motor and a hydrostatically supported z-axis of a milling machine are presented. Robust µ-controllers are designed and the developed methods are applied. The µ-controller for the first test rig is implemented manually in C-Code on a real industrial control unit. Due to the higher order of the µ-controller for the z-axis, the implementation is realized on a dSPACE System. Experimental results are presented and compared with state of the art technologies.
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