Force sensing considering periodic disturbance suppression based on high order disturbance observer and Kalman-filter

Disturbance rejection has been one of foremost issues in control engineering for the past several decades. Disturbance observer is an effective technique to diminish the adverse effects of disturbances. However, in practical applications, there are cases in which the estimated disturbance is affected by vibration phenomenon or additional oscillatory disturbance which is not addressed by the conventional disturbance observer. This paper proposes a high order disturbance observer for force sensing operation and suppression of periodic disturbance in order to achieve an efficient force control. To be practical, the noisy problem of the measurement is taken into account. A Kalman-filter is used in combination with the high order disturbance observer to reduce the noise effect. The feasibility of the proposed method is demonstrated by numerical simulation results.