Fabrication and Characterization of Small-scale Pneumatic Artificial Muscles for a Bio-Inspired Robotic Hand

摘要

As full-scale pneumatic artificial muscles (PAMs) are already known for their high workto-mass and force-to-volume ratios, research has been undertaken toward miniaturizing this actuator technology in order to develop small-scale PAMs that can be contained within the palm of a robotic hand to effect the desired movement of the robotic fingers. The first step in implementing these small-scale PAMs in a functional robotic manipulator was to design and characterize the miniature actuator. To that end, this paper presents the manufacturing process, experimental characterization, and analytical modeling of PAMs with millimeterscale diameters. First, a fabrication method was developed to consistently deliver low-cost, high-performance, miniature PAMs using commercially available materials. The quasi-static behavior of these PAMs was determined through experimentation on a single actuator with an active length of 39.16 mm (1.54 in) and a diameter of 4.13 mm (0.1625 in). Testing revealed the PAM’s full evolution of force with displacement over a broad spectrum of operating pressures, as well as the blocked force and free contraction capabilities at each pressure. This study also explores the nature of stress-softening in the PAM bladder, characterizing the change in actuator performance with increased use. Furthermore, this work compares the data from these experiments to two previously developed models for fullscale PAMs. With the inclusion of correction terms to account for physical phenomena encountered during testing, comparison between the models and the experimental results indicates that the improved models can accurately predict the behavior of these miniature PAMs below 4% contraction.