Walking Assist Robot: A Novel Non-Contact Abnormal Gait Recognition Approach Based on Extended Set Membership Filter

This work develops intelligent walking assist robot and gait rehabilitation robot for people with walking disabilities, where distinguishing of abnormal gait is crucial during safe human-robot interaction. Although vision sensors and wearable inertial devices are widely used in fall detection system, shielding of robot mechanical structure brings instability for visual detection method, and utilizing a large number of wearable sensors brings discomfort and complexity for users. Meanwhile, the frequent drag-to-drop gait has never been considered, which is a kind of intermittent state between normal state and fall. It's a major challenge to achieve an abnormal gait recognition system with high stability and good comfort. In this paper, a novel non-contact gait recognition method is proposed, which can identify fall and drag-to-drop gait in a stable and comfortable way. Leg movement data is obtained by a built-in-robot camera, which accurately describes gait law through contrast test and error analysis. New-type ESMF algorithm is proposed to evaluate knee angle precisely and resolve the issue of marker point loss effectively. The comprehensive experiments have shown that this innovative approach calculates accurately knee angle in the walking process so as to recognize the phenomenon of drag-to-drop gait and fall. Additionally, this method having a sound theoretical basis and higher stability solves the issue of marker point loss, which could be applied to a walker with a similar structure for elderly and disabled in a comfortable way.