Haptic linear paths for arm rehabilitation in MS patients

Force feedback in the context of a rehabilitation program may have its benefits. The generated forces can be used to assist, support or oppose the patients according to their personal needs and abilities. Using the Phantom haptic device, we conducted a pilot study focussing on the rehabilitation of the upper limbs in MS patients. Apart from the promising clinical results, we found that only a few haptic effects are commonly necessary. Among them is a `linear path', a haptic effect that generates the necessary forces to follow a path defined by two or more points in space. In this paper we motivate why the current implementations in existing haptic APIs (such as H3D) are not completely suitable. We propose two possible alternative implementations based on our requirements: one using rounded polygons, another using cardinal splines. It will turn out that both solutions are equivalent, but depending on the application one of both will be more suitable.