Noncircular Cable-Pulley Mechanisms Used for Equilibrating the Wheelchair Backrest

Wheelchairs are the most common way to provide accessibility to people with disabilities but the transfer of patients in and out remains a challenge. With the development of technology, progress has been made in this direction through the development of mechanisms for reconfiguring wheelchairs and various solutions have been proposed, but these still do not solve the problem in a simple, easy, cheap, and efficient way. Consequently, to facilitate the patient’s transfer, the wheelchair reconfiguration mechanisms must be able to fulfil several functions, such as morph into chair, bed, raising to an orthostatic position, toilet, turning on one side and others. This paper proposes a force balacing mechanism to be used for the backrests and footrests with cables and human or servomotor actuation. The proposed mechanism is designed to minimize human/actuator contribution when backrest is vertical and needs to move to horizontal position or vice versa. It is to note that the proposed mechanism has substantial force contribution for the whole range of motion (horizontal to vertical) and not only at the ends of range of motion.