Walking assistance using artificial primitives

Abstract

Bio-inspiration in robotics deals with applying biological principles to the design of better performing devices. In this work, we propose a novel bio-inspired framework using motor primitives for locomotion assistance through a wearable cooperative exoskeleton. In particular, the use of motor primitives for assisting different locomotion modes (i.e., ground-level walking at several cadences and ascending and descending stairs) is explored by means of two different strategies. In the first strategy, identified motor primitives are combined through weights to directly produce the desired assistive torque profiles. In the second strategy, identified motor primitives are combined to serve as neural stimulations to a virtual model of the musculoskeletal system, which in turn produces the desired assistive torque profiles. The paper further reports the results of an experiment conducted with healthy participants where the proposed strategies were tested for the first time with a wearable robotic exoskeleton for hip assistance. Several volunteers performed the task of ground-level walking in different conditions. These experimental activities highlighted the capacity of volunteers to naturally interact with the device and benefit from the assistance in terms of physical effort.