Human-robot coordination stability for fall detection and prevention using cane robot

A cane-type walking-aid robot with a ball joint is developed for assisting old people's walking. Considering both the overturn of robot and the stability of human user, this paper presents a new concept of Human-Robot Coordination Stability (HRCS) which can describe the stability of the integrated human-robot system during the user operating the cane robot. HRCS is characterized by a stability region generated from the user's stability measured by posture information and the robot stability obtained by Force-Angle (FA) measure method. If the human-robot system runs out of the stability region, the fall tendency is then detected. To guarantee the safety of both the user and robot, a fall prevention control strategy is also proposed. The fall prevention control is executed to ensure the system staying in the stability region when any fall tendency is detected. Finally, we conducted experiments in real cane robot and the results illustrate the validity of the fall detection and prevention method.