A novel fall prevention scheme for intelligent cane robot by using a motor driven universal joint

In this study, we propose a novel fall prevention scheme for an omni-direction type cane robot by using a DC motor driven universal joint. The cane robot which is driven by three omni-wheels is called Intelligent Cane Robot (iCane). It is designed for aiding the elderly and handicapped people walking as shown in Fig.1. The motion of cane robot is controlled for both normal and abnormal walking conditions. The user's normal walking aided by the cane robot, a concept called “Intentional Direction (ITD)” is proposed. Guided by the online estimated ITD, we apply the admittance control method in the motion control of cane robot. For the abnormal walking, we mainly studied the case of user's fall down. The center of gravity (COG) of user can be estimated from the angle of an inverted pendulum which represents human dynamic model. Fall prevention algorithm based on the relationship between user's COG and the cane is proposed. Because the size of the cane robot is small, when the robot is preventing the user falling down, firstly, the stability of the cane robot should be ensured. A universal joint which is driven by two DC motors is used to reduce the moment causing the cane robot falling over. The proposed method is verified through experiments.