Concept and design of a modular lower limb exoskeleton

Powered lower limb exoskeletons become more and more common and are used for different applications such as rehabilitation and human strength augmentation. However, many of the existing designs are limited to a very specific task. We present the concept and design of a modular, reconfigurable lower limb exoskeleton that can be adapted with respect to it's kinematics and actuation to a wide range of users and applications. The introduced modular design allows to compose lower limb exoskeletons with up to four degrees of freedom per leg: abduction/adduction of the hip and flexion/extension of the hip, knee, and ankle. Each passive joint can be extended by a module in terms of functionality, e.g. by actuation or spring stabilization. Three different modules are introduced: one actuator for active support and two spring modules that stabilize the joint around an equilibrium position. Using the presented components, three exemplary systems are composed and discussed: An active hip support exoskeleton, a fully articulated lower limb exoskeleton for gait support and a system for treadmill based gait rehabilitation. The three designs show that the concept of a modular exoskeleton is feasible and that it can be an alternative to a specialized system for environments with changing requirements, for example in rehabilitation or research.