“…In [29], human's moving direction is estimated using the Kalman filter and it is used for the position control of the robot. In [30], [31], human's motion intention is estimated by minimizing the interaction force and the robot's reference trajectory is adapted accordingly. The above research works [25], [26], [27], [28], [29], [30], [31] mainly focus on reference adaptation based on human's motion intention, and the control objective is to minimize the interaction force between human and robot and the desired reference trajectory is considered to be the same as human's intention.…”