How to Transform an Upper Limb Prosthetic Arm in a Wheelchair Arm

A myoelectric upper limp prosthetic arm is an aid with several degrees of freedom, designed to allow a patient to perform several movements (typically opening-closing the hand, rotating the wrist clockwise and counter clockwise, flexing-extending the elbow). The new version of the INAIL (Istituto Nazionale Assicurazioni Infortuni sul Lavoro, i.e. Italian National Assurance Institute for work accidents) prosthetic arm includes also a shoulder unit, able to perform two movements (abduction/rotation). Seeing this aid from another point of view, overturning the idea of prosthetic arm, it can be obtained a robotic arm that can be installed on a wheelchair, using the same motors, the same structure, the same electronic and mechanical components. This device is already able to perform task such as reaching/manipulating objects, and can be used to assist the tasks of eating and interacting with the environment. Of course the device must be a little bit adapted (a grip with a real hand shape is not appropriate!), and its purposes, when mounted on a wheelchair, are different from the ones related to an amputee patient. Anyway, even if it cannot have the same performance of a Manus (R) arm, the INAIL prosthetic arm is cheaper and overall is already funded by the Italian National Health Service, which is a very good start point for this project. The aim of the paper is then to investigate the possibility of this transformation and to illustrate the capability of the first prototype in term of range of movement, usability and versatility.