Design and fabrication of a modularized humanoid arm with pneumatic artificial muscles

Panford, Ronny Paa Kwesi
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With increase investment in the development of humanoids, there offers a window of opportunity to leverage the rapidly growing market of soft robotics in our strides towards more accurate biomimetic motion and study of humanoids and their applicatory areas. This project encompasses the systematic design, implementation and testing of a lightweight low-cost humanoid arm that utilizes Pneumatic Artificial Muscles (PAM). These muscles do not only exhibit twistable and bendable human-like muscle contractions but modularized in design to stand as a complete controllable unit which may be dissociated and mountable on a support frame on its own. This project achieves the design of a mobile arm unit with total weight of less than 2kg of which is distributed with one-third the weight being borne on the arm. The realized powerto- weight ratio of near 5W per kilogram, under an approximate 13.5 litre per minute rate of pressurization is of desired muscle force, and flex speeds. The McKibben tubing choice of PAM is experimentally validated under a linear fit for its force-contraction performance. This design makes considerable strides in cutting down weight, leveraging power, and being much cheaper than existing solutions. Comparable lightweight arm designs of which some are commercially available have weights of 38kg (Mitsubishi PA10arm), 14kg (KUKA lightweight arm), etc., with power-to-weight ratios of near 1W/kg. However, this project designs cuts down these weights drastically to about 2kg (without any sensory unit yet) and more than doubles the power to weight ratios mentioned.
Capstone Project submitted to the Department of Engineering, Ashesi University in partial fulfillment of the requirements for the award of Bachelor of Science degree in Mechanical Engineering, May 2021
soft robotics, humanoid arm