A design method of observers for bilateral control using dc brushed motor

Abstract

This paper proposes a novel design method of disturbance observer (DOB) and reaction force observer (RFOB) for acceleration-based bilateral control (ABC) utilizing DC brushed motor (abbreviated as DC motor later). ABC is one of the control method to enable the transmission of haptic sensation between master and slave robots. In order to transmit highly precise haptic sensation, both DOB and RFOB are used for ABC. Conventionally, in case of utilizing these observers, a motor has been considered to be driven by an ideal current source by utilizing the motor driver which has a current minor loop. The gain of current minor loop must be set large value in order to improve current tracking performance. However, there is a limit to increase the gain since it is affected by the the time delay of current minor loop. Therefore, this paper proposes design methods for DOB and RFOB without using current minor loop. Proposed observers estimate disturbance force from acceleration reference, voltage reference, and acceleration response by utilizing novel nominal model for DC motor. Proposed method can improve disturbance estimation performance. Moreover, by utilizing proposed method, DC motor can be controlled without using current sensor. The validity of proposed methods are experimentally verified.