Patent ID: 8733207

Claim:
A method of driving a joint device comprising a drive unit and a differential speed reducer provided between a first link and a second link, the joint device controlling drive of the first link and the second link as joints, wherein the differential speed reducer comprises an internal gear, an intermediate gear, and an external gear, and the drive unit comprises a first motor and a second motor, the method comprising: fixedly connecting the first motor and the second motor to the first link; coupling an output shaft of the first motor to one of the internal gear, the intermediate gear, and the external gear of the differential speed reducer; coupling an output shaft of the second motor to one of the internal gear, the intermediate gear, and the external gear of the differential speed reducer which is different from the gear coupled to the output shaft of the first motor; and coupling to the second link one of gears of the internal gear, the intermediate gear, and the external gear of the differential speed reducer which is different from the gear coupled to the output shaft of the first motor and the gear coupled to the output shaft of the second motor; and rotating both of the first motor and the second motor at a rotational speed larger than zero, and stopping the second link by differentiating the rotational speed of the first motor and that of the second motor when the first link and the second link are relatively stopped to keep a joint angle fixed.