Pulling your strings

Our key motivation is the rehabilitation of individuals recovering from stroke or other neurological insult. The torque exerted by a cable-driven joint is the cross product of the line of action of the cable, known as the moment arm, and its tension. The subject of this article delves into this latter, less-studied quantity associated with torque. The concept of moment arm manipulation of a cable-driven joint is introduced, developed, formalized, and then examined with experiments on a physical, single-joint device. This method of moment arm manipulation, referred to as the moment arm manipulation for remote induction of net effective torque (MARIONET), is found to have distinct advantages that make it feasible for home rehabilitation as well as potential outside of the field.