A novel flat modular pneumatic artificial muscle

Abstract

This paper presents a novel flat modular pneumatic artificial muscle (FMPAM) consisting of thin-film cylinder modules, which have no expansion in the thickness direction when pressurized to generate transverse force, and transverse-to-longitudinal deformation translation structures around modules, which accumulate the distributional deformation and ultimately obtain large cumulative deformation and output force. The FMPAM is designed for contractile assistance in soft wearable robots to achieve no squeezing on users’ skin and better wearing comfort. This design combines the advantage of fast time response of positive-pressure pneumatic artificial muscles (PAMs) and the features of good flexibility of negative-pressure ones. Additionally, the design avoids the disadvantages of relatively large thickness or radical expansion of positive-pressure PAMs. In this paper, the design and processing methods of the FMPAM are introduced in detail. It is worth mentioning that the whole FMPAM is printed utilizing the same type of material at one time. Identification of the module model is carried out. Module net output force and restoring force test benches are built to acquire experimental data for assisting the modeling. The shape of the film and modular output force can be predicted during actuation. Experimental results show that low predictive error can be obtained. Finally, an output force test bench, various radius arches and an arm-like structure are built to verify the output characteristics of the FMPAM: good compliance to surfaces with different radiuses, long-lasting endurance (more than 10 000 reciprocating cycles), and high response speed (100 Hz), indicating that the proposed design can provide theoretical guidance and a good alternative for soft wearable robot actuators.