H-Man: Characterization of a novel, portable, inexpensive planar robot for arm rehabilitation

In the past decades there has been an increasing interest in the design of robotic platforms suitable to assist the conventional motor therapy and/or to study human motor control. Most of the proposed solutions, however, come with intrinsic limitations that in turn limit the final use of the device itself. For instance, encumbrance, sophisticated control architectures and high costs translate into cumbersome and expensive devices whose diffusion is still limited to laboratories and specialized clinical settings. This paper presents a novel, two degrees-of-freedom planar device conceived according to three main principles: portablility, cost-effectiveness and ease of control. The key ingredient of the device is a planar H-shaped cable differential mechanism which ensures a constant Jacobian and a homogeneous perceived inertia over the entire workspace. The paper presents the mechanical design as well as the performance evaluation in terms of bandwidth, Z-width and perceived impedance.