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Energy regenerative damping in variable impedance actuators for long-term robotic deployment

Research output: Contribution to journalArticle

Original languageEnglish
Number of pages13
Early online date12 Jun 2020
Publication statusE-pub ahead of print - 12 Jun 2020

Bibliographical note

Conditionally accepted in Dec 2019. A preprint version is on


  • WU-t-ro2020_v2

    WU_t_ro2020_v2.pdf, 1.21 MB, application/pdf


    Accepted author manuscript

    CC BY

King's Authors


Energy efficiency is a crucial issue towards longterm
deployment of compliant robots in the real world. In
the context of variable impedance actuators (VIAs), one of the
main focuses has been on improving energy efficiency through
reduction of energy consumption. However, the harvesting of
dissipated energy in such systems remains under-explored. This
study proposes a variable damping module design enabling
energy regeneration in VIAs by exploiting the regenerative
braking effect of DC motors. The proposed damping module
uses four switches to combine regenerative and dynamic braking,
in a hybrid approach that enables energy regeneration without
a reduction in the range of damping achievable. A physical
implementation on a simple VIA mechanism is presented in
which the regenerative properties of the proposed module are
characterised and compared against theoretical predictions. To investigate the role of variable regenerative damping in terms of energy efficiency of long-term operation, experiments are reported in which the VIA, equipped with the proposed damping module, performs sequential reaching to a series of stochastic targets. The results indicate that the combination of variable stiffness and variable regenerative damping results in a 25% performance improvement on metrics incorporating reaching accuracy, settling time, energy consumption and regeneration over comparable schemes where either stiffness or damping are fixed.

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