Motion control is widely used in industry applications. One of its key components is the disturbance observer, which estimates a disturbance torque of a motion system and realizes a robust acceleration control. A disturbance observer observes and suppresses the disturbance torque within its bandwidth. Motion systems have started to spread in society and they are required to have the ability to interact with unknown environments. Such a haptic motion requires much wider bandwidth. However, since the conventional disturbance observer attains the acceleration information by the second-order derivative of a position response, the bandwidth is limited due to the derivative noise. To enlarge the bandwidth of a disturbance observer, this paper proposes a position-acceleration integrated disturbance observer (PAIDO). Since an acceleration sensor is implemented in it, the control performance of the PAIDO is superior to the conventional one. In this paper, the PAIDO is applied to force control and the viability of the proposed method is confirmed by fast Fourier transformation analyses. The experimental results show the viability of the proposed method.
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