Wideband motion control by acceleration disturbance observer

Motion control has been widely used in industry applications. One of the key technologies of motion control is a disturbance observer, which quarries a disturbance torque of a motion system and realizes a robust acceleration control. The disturbance observer can observe and suppress the disturbance torque within its bandwidth. Recent motion systems begin to spread in the society and they are required to have ability to contact with unknown environment. Such a haptic motion requires much wider bandwidth. However, since the conventional disturbance observer attains the acceleration response by the second order derivative of position response, the bandwidth is limited due to the derivative noise. This paper proposes a novel multi-sensor based acceleration disturbance observer (MADO). The proposed MADO uses an acceleration sensor for enlargement of bandwidth. Generally, the bandwidth of an acceleration sensor is from 1 Hz to more than 1kHz. To cover DC range, the second order derivative of position is integrated. The integrated acceleration value realizes lower observation noise and higher bandwidth than a conventional estimated acceleration. Thus, the proposed MADO can get at wide frequency response than conventional one. And, it made dramatically more responsive a position control and a force control. Results are verified by simulation.