Assistive Walker with Passive Sit-to-Stand Mechanism for Toileting Independence

This paper proposes a novel walker with a passive sit-to-stand assistive mechanism for elderly people with weak lower limb muscles. The aim of the proposed device is to facilitate independent toilet usage by supporting the sit-to-stand posture transition and walking of the user. The mechanism design is based on utilizing the center of mass transition through the upper body motion of the user. A passive mechanism powered by gas springs realizes the posture transition using the center of mass transition. The supporting torque produced by the device can be adjusted depending on the user's remaining function by changing the fixing position of the gas springs. The design also aims to allow the user to use a toilet without a transition between the toilet seat and device. Furthermore, the mechanism is integrated with a walker, which provides locomotion capability for preventing deterioration in activities of daily living. In this paper, we describe the detailed design process of the mechanism and two preliminary experiments with three healthy participants to investigate its effectiveness.