A five-fingered hand exoskeleton driven by pneumatic artificial muscles with novel polypyrrole sensors

Purpose - The purpose of this paper is to review the challenges present in the development of hand exoskeletons powered by pneumatic artificial muscles. This paper also presents the development of a novel strain sensor and its application in a five-fingered hand exoskeleton. Design/methodology/approach - The issues of current hand exoskeletons powered by pneumatic artificial muscles are examined by studying the artificial muscles and the human hand anatomy. Traditional sensors are no longer suitable for applications in hand exoskeletons. A novel strain sensor was developed by depositing a conducting polymer called polypyrrole onto a natural rubber substrate through vapor phase polymerization and is used in the authors' five-fingered hand exoskeleton. Findings - The error of measurements from the polypyrrole strain sensor in controlling the actuation of pneumatic artificial muscles is within 1.5 mm. The small physical size and weight of the novel polypyrrole strain sensor also helped to keep the exoskeleton's profile (less than 20 mm) and total weight low (<1 kg). Originality/value - The novel strain sensor allows the realization of hand exoskeletons that are lightweight, portable and low profile. This improves the comfort and practicality of hand exoskeletons to allow their usage outside the research environment.