Dynamic compensation of torsional oscillation in paper machine sections

Torsional oscillations bound the speed loop bandwidth (BW) of industrial drives and servo systems, deteriorating the transient response to commands and to disturbances. This is especially harmful in multi-drive systems, like paper machines, that need to run synchronized. This paper presents two methods to dynamically compensate the torsional oscillations produced by the compliant components between the motor and the load: either a notch filter or acceleration feedback based on the rigid-body Luenberger observer. The evaluation includes the effect of the reducer backlash, whereby both time and frequency domain responses are used to compare the benefits of each technique in a typical paper machine section. Results show that both methods, if properly tuned, are effective techniques to reduce torsional oscillations, and are robust to parameter variations