A Fundamental Study of Obstacle Avoidance in Partly Interrupted Sight

Abstract

Tripping over, which is one of the causes of falling, is caused by lack of recognizing obstacles. The purpose of this study is to investigate obstacle avoidance under the condition of partly interrupted sight. Six young adults stepped over an obstacle of 4.8 cm high under four conditions: (1) without interrupted sight; (2) under partly interrupted sight with 35% of subject's stride; (3) under that with 100% of subject's stride; (4) under that with 200% of subject's stride. The 3D motion of stepping over an obstacle was recorded together with ground reaction force. Step length during approaching and stepping over an obstacle, clearance, toe-obstacle distance, heel-obstacle distance and hip, knee and ankle joint moments were estimated with Vicon system. Additionally, the sensory tests about fear for partly interrupted sight after each trial were made. The results showed that clearance and toe-obstacle distance were extended during stepping over an obstacle with larger partly interrupted sight. It is suggested that the motion changes are caused by fear for partly interrupted sight and the conscious to decrease falling risks.