Control and controllability of microswimmers by a shearing flow

Clément Moreau, Kenta Ishimoto, Eamonn A. Gaffney, Benjamin J. Walker

Research output: Contribution to journalArticlepeer-review

9 Citations (SciVal)

Abstract

With the continuing rapid development of artificial microrobots and active particles, questions of microswimmer guidance and control are becoming ever more relevant and prevalent. In both the applications and theoretical study of such microscale swimmers, control is often mediated by an engineered property of the swimmer, such as in the case of magnetically propelled microrobots. In this work, we will consider a modality of control that is applicable in more generality, effecting guidance via modulation of a background fluid flow. Here, considering a model swimmer in a commonplace flow and simple geometry, we analyse and subsequently establish the efficacy of flow-mediated microswimmer positional control, later touching upon a question of optimal control. Moving beyond idealized notions of controllability and towards considerations of practical utility, we then evaluate the robustness of this control modality to sources of variation that may be present in applications, examining in particular the effects of measurement inaccuracy and rotational noise. This exploration gives rise to a number of cautionary observations, which, overall, demonstrate the need for the careful assessment of both policy and behavioural robustness when designing control schemes for use in practice.

Original languageEnglish
Article number211141
JournalRoyal Society Open Science
Volume8
Issue number8
DOIs
Publication statusPublished - 11 Aug 2021

Bibliographical note

Funding Information:
Data accessibility. The data used and generated in this paper is freely available from the University of Oxford Research Archive (ORA) via the link http://dx.doi.org/10.5287/bodleian:wr6d1YEVP. Authors’ contributions. C.M. carried out the controllability analysis, drafted and critically revised the manuscript, and designed the study. K.I. and E.A.G. designed the study and critically revised the manuscript. B.J.W. carried out the robustness analysis, drafted and critically revised the manuscript, and designed the study. Competing interests. At the time of writing, Kenta Ishimoto is a Board Member of Royal Society Open Science, but had no involvement in the review or assessment of the paper. Funding. C.M. is a JSPS International Research Fellow (PE20021). K.I. acknowledges JSPS-KAKENHI for Young Researchers (grant no. 18K13456) and JST, PRESTO, Japan (grant no. JPMJPR1921). C.M. and K.I. were partially supported by the Research Institute for Mathematical Sciences, an International Joint Usage/Research Center located at Kyoto University. B.J.W. is supported by the UK Engineering and Physical Sciences Research Council (EPSRC), grant no. EP/N509711/1.

Funding Information:
C.M. is a JSPS International Research Fellow (PE20021). K.I. acknowledges JSPS-KAKENHI for Young Researchers (grant no. 18K13456) and JST, PRESTO, Japan (grant no. JPMJPR1921). C.M. and K.I. were partially supported by the Research Institute for Mathematical Sciences, an International Joint Usage/Research Center located at Kyoto University. B.J.W. is supported by the UK Engineering and Physical Sciences Research Council (EPSRC), grant no. EP/N509711/1.

Publisher Copyright:
© 2021 The Authors.

Keywords

  • controllability
  • flow control
  • microswimmer control
  • robustness

ASJC Scopus subject areas

  • General

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