A basic study for a robotic transfer aid system based on human motion analysis

A metal hydride (MH) actuator uses the reversible reaction between heat ene rgy and mechanical energy of a hydrogen-absorbing alloy and moves smoothly without any noise. Moreover, the actuator is compact, light and has adequat e compliance. In this paper, some experiments concerning human motion patte rns were carried out in order to adopt the MH actuator to the transfer aid system. The results were evaluated from a biomedical engineering viewpoint in order to obtain the optimal parameters for transferring the disabled fro m a bed to a wheelchair and vice versa (transfer aid). Sagittal plane kinem atics, surface electromyographic signals (EMG) obtained from lower limbs, g round reaction forces and foot pressure distribution were measured using a three-dimensional motion analyzer. From the experimental results, it was fo und that the motion of the transfer aid was smooth when the initial angle o f the ankle was 70 degrees, The best initial angle of the trunk was also fo und to be about 45 degrees while standing from a bed, However the initial a ngle of the trunk was best at 60 degrees when a person was in the process o f sitting down on a wheelchair. Furthermore, a knee pad which supports the lower limbs requires flexibility in the range of 0.1-0.2 kgf/mm.