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RESEARCH PRODUCT

Design and Characterization of a Miniature Hydraulic Power Supply for High-Bandwidth Control of Soft Robotics

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Soft robotics holds enormous promise for a wide class of applications. However, system controllability, bandwidth, portability, and energy efficiency of soft robot power supplies are often inadequate. Soft robotics desperately needs improved solutions to drive soft actuators either pneumatically or hydraulically. This research paper offers a contribution to bridge this gap. It deals with small-scale power supplies for hydraulically-driven soft robots based on fluidic elastomer actuators in the power range 5-400 W. A design procedure for such power supplies is developed with an emphasis on high-bandwidth control. The performance requirements are established based on a literature survey, and design alternatives are discussed. Then, a prototype consisting of a $0.102 c^{3}$/rev positive-displacement, external gear pump directly driven by a 70 W brushless dc motor is built and experimentally characterized. Control of the targeted soft robots results possible because the proposed power supply has high-bandwidth varying between about 12 and 30 Hz (i.e., well above the actuators’ mechanical frequency). The power supply’s energy efficiency is also measured, and areas for its improvement are identified. The proposed solution is feasible, applicable to autonomous soft robots, scalable to the power levels of interest, and possibly useful for both tethered soft robots and rigid/semi-rigid robots.