Characterisation, Design and Experimentation of a Fabric Based Wearable Joint Sensing Device

Abstract

The use of conductive fabrics (CF) in the design of wearables for joint sensing has recently received much interest in a wide range of applications such as robotics, rehabilitation, personal wellness, sports, and entertainment. In this paper, we evaluate a new wearable device concept that comprises of a CF strain-voltage sensor embedded as part of an inverted slider-crank mechanism for joint extension sensing. This has the benefit of not requiring anthropometric information from the user to related the joint parameters to the fabric strain readings, as opposed to an existing design. Firstly, we characterize the electromechanical property of a commercially available CF. Secondly, we formulate the geometric synthesis procedure of the joint sensing device as a constrained revolute joint system, where the CF is designed and introduced as an RPR chain to obtain an inverted slider-crank linkage. Lastly, we develop and validate our wearable joint sensing device against an experimental setup that represents an elbow joint. Our concept shows that our proposed joint sensing device can track the elbow extension motion of 140° with a maximum error of 7.66%.