Real time posture control for stability improvement of intelligent cane robot

For aiding the elderly who have muscle weakness on lower limbs, an intelligent cane robot system was proposed and constructed. An omni-directional mobile robot with three omni-directional wheels was used as the base. An aluminum stick was fixed on the mobile base of cane robot. We proposed a Concept called “intentional direction (ITD)” for estimating the user´s walking intention by analyzing the signal of a 6-axis force/torque sensor which is fixed to the handle of stick. As a care-nursing device, the cane robot was designed to assist the elderly in both indoor and outdoor environments. Therefore the size and weight of cane robot should be minimized. But in that case, there is high risk that the cane robot would be pushed over by the user. Therefore, A universal joint driven by two DC motors was designed to improve the stability of cane robot by controlling the posture of the stick. In this paper a constrained nonlinear multivariable algorithm was designed to optimize the stable posture of cane robot. By controlling the posture of stick, the maximums sufferable torque moment which lead to cane robot falling over can be increased. The experimental results show that the stability of cane robot can be enhanced effectively.