Motion control of passive intelligent walker using servo brakes

We propose a new intelligent walker based on passive robotics that assists the elderly, handicapped people, and the blind who have difficulty in walking. We developed a prototype of the Robot Technology Walker (RT Walker), a passive intelligent walker that uses servo brakes. The RT Walker consists of a support frame, two casters, two wheels equipped with servo brakes, and it has passive dynamics that change with respect to applied force/moment. This system is intrinsically safe for humans, as it cannot move unintentionally, i.e., it has no driving actuators. In addition, the RT Walker provides a number of navigational features, including good maneuverability, by appropriately controlling the torque of servo brakes based on RT. We propose a human adaptive motion control algorithm that changes the apparent dynamics to adapt to user difficulties, and an environmentally adaptive motion control algorithm, which incorporates environmental information to provide obstacle/step avoidance and gravity compensation functions. The proposed control algorithms are experimentally applied to the RT Walker to test their validity.