An actuating device for orthosis including a housing, a motor, a transmission disposed in the housing, and an actuating arm. The transmission is operatively connected to the motor such that the motor provides power to the transmission. The transmission includes a first stage, a second stage, and a third stage. The first stage has a first sprocket, a second sprocket, and a first drive belt tensioned between the first sprocket and the second sprocket. The first sprocket is attached to a shaft of the motor. The second stage has a third sprocket, a fourth sprocket, and a second drive belt tensioned by the third sprocket and the fourth sprocket. The third sprocket is attached to the second sprocket of the first stage. The third stage has a fifth sprocket, a sixth sprocket, and a third drive belt tensioned by the fifth sprocket and the sixth sprocket. The fifth sprocket is attached to the fourth sprocket of the second stage. The transmission additionally includes a first shaft and a second shaft. The second sprocket, the third sprocket, and the sixth sprocket are attached to the first shaft, and the fourth sprocket and the fifth sprocket are attached to the second shaft. The actuating arm is operatively connected to the sixth sprocket of the third stage of the transmission such that the power provided to the transmission by the motor causes the actuating arm to provide an output torque.
