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Energy efficiency of mobile soft robots


The performance of mobile soft robots were usually characterized by their locomotion/velocity efficiency, whereas the energy efficiency is a more intrinsic and fundamental criterion for the performance evaluation of independent or integrated soft robots. In this work, a general framework is established to evaluate the energy efficiency of mobile soft robots by considering the efficiency of energy source, actuator and locomotion, and some insights for improving efficiency of soft robotic systems are presented. Proposed as the ratio of the desired locomotion kinetic energy to the input mechanical energy, the energy efficiency of locomotion is found to play a critical role in determining the overall energy efficiency of soft robots. Four key factors related to the locomotion energy efficiency are identified, that is, the locomotion modes, material properties, geometric sizes, and actuation states. It is found that the energy efficiency of most mobile soft robots reported in the literatures is surprisingly low (mostly below 0.1%), due to the inefficient mechanical energy that does not contribute to the desired locomotion essentially. The comparison of locomotion energy efficiency for several representative locomotion modes in literatures is presented, showing a descending ranking as: jumping >> fish like swimming > snake like slithering > rolling > rising/turning over > inchworm like inching > quadruped gait > earthworm like squirming. Besides, considering the same locomotion mode, the soft robots with lower stiffness, higher density and larger size tend to have higher locomotion energy efficiency. Moreover, a periodic pulse actuation instead of the continuous actuation mode may significantly reduce the input mechanical energy, thus improving the locomotion energy efficiency, especially when the pulse actuation matches the resonant states of the soft robots. The results presented herein indicates a large and necessary room for improving the locomotion energy efficiency, which is of practical significance for future development and application of soft robots.

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Publication details

The article was received on 11 Aug 2017, accepted on 12 Oct 2017 and first published on 13 Oct 2017

Article type: Paper
DOI: 10.1039/C7SM01617D
Citation: Soft Matter, 2017, Accepted Manuscript
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    Energy efficiency of mobile soft robots

    L. Shui, L. Zhu, Z. Yang, Y. Liu and X. Chen, Soft Matter, 2017, Accepted Manuscript , DOI: 10.1039/C7SM01617D

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