~Introduction

For those such as stroke survivors, physical therapy is key to retrain and strengthen muscles and regain motor skills that may have been lost. One such exercise is the movement between the two positions shown in Figure 1, used to work the intrinsic muscles of the hand. The goal for our project is to build a hand exerciser for the four fingers, excluding the thumb, to facilitate that movement to be used for physical therapy. While the ideal machine would be able to do both fully passive and partially passive (to allow for some movement from the patient), our focus was to create a fully passive machine, as making it partially passive after accomplishing that would mostly be a matter of controls.

In order to do this using one motor, we decided to drive the motion from the proximal phalanx. We also assumed a generally linear trajectory for the fingertips, with a slight incline up towards the palm. With these in mind, we set out to design a fully passive hand exerciser.

Figure 1: Hand Positions