Design and control of spherical shoulder exoskeletons for assistive applications

The shoulder complex is the most complex joint in human's four limbs and this poses a big challenge in the exoskeleton design to achieve a mechanism able to generate the desired motion while structurally complying with human anatomy. This chapter presents a novel design of an exoskeleton shoulder mechanism and its control. The new design is a hybrid mechanism that consists of two revolute joints connected together via a double parallelogram linkage (DPL). By virtue of a DPL, a remote center of rotation can be established for a spherical mechanism with three-degree-of-rotations. In the chapter, the working principle of the shoulder mechanism is described. The kinematics of the mechanism is analyzed. Mechanism design and exoskeleton control are also presented.