Design and Dynamic Analysis of an Arm Exoskeleton with Cable Tendon for Shoulder Joint Motion

In this study, a portable upperlimb exoskeleton is designed for the purpose of rehabilitation and helping the disabled people to do their daily activities. This exoskeleton has two active and one passive degrees of freedom for the shoulder joint. In this system, the idea of cable transmossiom mechanism and guidance pulley with the ability to change the force direction is used. The two active DOFs of the shoulder joint is achived only by pulling one cable for each axis based on the novel design of this mechanism. Each axis of the shoulder is driven independently which implies that a single axis can be installed on the arm. This exoskeleton does not impose any limitation on the vertical motion of the scapula. In addition, it is inexpensive, lightweight and can easily be used. In this paper, after introducing the exoskeleton system, the required motor torques for generating a prescribed task are obtained. In the next step, the kinematic and dynamic equations of this system are derived. By simulating the exoskeleton in CATIA and MATLAB softwares, and presenting the results, the performance of the exoskeleton is evaluated. The results show that this novel exoskeleton system posses an excellent capacity to perform the rehabilitation excersises for shoulder joint.