This paper proposes N-degree-of-freedom (N-DoF) control for single-input and single-output based systems. This method relaxes the water-bed effect, which limits the capacity to suppress disturbances and noise using multiple sensors. The system's design procedure for the control system and nominal stability conditions are introduced. N-DoF control is then compared with classical two-DoF control and with Kalman filter using simulations and experiments of motor systems with an encoder and an accelerometer. The results indicate that N-DoF control achieves an enhanced disturbance and an oscillation suppressing performance simultaneously. Moreover, N-DoF control is applied to two-mass systems and verified by using numerical simulation. The characteristics are introduced and compared with several conventional approaches. The results suggest that N-DoF control incorporates all the characteristics of the other methods, and its disturbance and vibration suppression capability is demonstrated.
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