A Method for Evaluating Gait Disturbance of Evacuees in Disasters Using Singular Value Decomposition

On-site emergency care is critical in rescue operations in times of disasters or calamities. In order to identify the injured effectively and thus to provide quick rescue, a precise and convenient method is being developed to automatically analyze the sufferers' movements. In this paper, we propose a method for evaluating gait disturbance of evacuees in disasters. Singular value decomposition is used to acquire feature patterns from the time-series acceleration data. In an experiment, in order to verify the usefulness of the proposed method, three levels of walking difficulty in the lower limbs are simulated by constraining the knee joint and ankle joint of the right leg, and the accelerations of the middle of shanks and the back of the waist are measured and analyzed. The results showed that the first singular values inferred from the acceleration data of the shanks decreased with increase of the constraint to the joints. The first singular values of the acceleration data of the shanks were suggested to be reliable criteria to evaluate walking difficulty. A rescue plane, which can provide quantitative visual information of gait disturbance level, is defined by the singular values. The rescue plane can be used by the doctors and nurses as a useful tool for quick and precise diagnosis.