Cyclic disturbance suppression control for harmonic magnetic gear

This paper proposes a control method that attenuates adverse effects due to cogging torque on the vibratory system. A conventional controller utilizes a disturbance observer to estimate the cogging torque; however, the observer usesa filter that causes an estimation delay. If the cut off frequency is high enough, the delay may be negligible, but the estimated disturbance (cogging torque) will be contaminated with vibration. Instead, the proposed method uses a filter with a low cut off frequency; the estimation delay is compensated for by the leading angle, then it is used to attenuate the disturbance in the next rotational duration. The experimental results showed that the proposed method was clearly superior: the RMS magnitudes of the velocity control error were drastically reduced.