Control strategies for structural chatter suppression using a rack and pinion drive

Chatter vibrations are a major limitation for machining operations and lead to productivity reduction, low tool life and poor surface finish. Active damping with the machine tool’s own drives can be used to increase the stability limit related to structural modes of the machine. Various feedback strategies can be used measuring the vibrations with an external accelerometer and feeding back this signal to the position, velocity or current setpoint of the drive. The objective of this article is to build a model based on experimental data to predict the effect of the standard controlp arameters and additional acceleration feedback controller on the Frequency Response Function of the machine. Experimental tests are carried out on an electronically preloaded rack and pinion drive. The open loop Frequency Response Functions of the dynamical system are measured and the closed loop responses are calculated using Linear Fractional Transformations representing the control structure of the Multi Input Multi Output system.