Abstract

Pneumatic artificial muscles (PAMs) are high power-toweight ratio actuators with considerable potential in biomimetic robotics and orthotics due to their similarities with human skeletal muscle. However, precise position control is difficult to achieve due to the highly nonlinear nature of the actuators and the pneumatic systems driving them. A wide range of nonlinear controllers have been proposed to-date, but none have been shown to be entirely satisfactory, and are often optimised for only one region of the PAM's travel. In this paper, a gain-scheduled position controller is designed that aims to achieve equal tracking performance across the entire travel of the PAM. Selected scheduling variables include actuator displacement and error direction, with controller gains defined by 'normalisation curves'determined by data from open-loop characterisation tests. The experimental system consists of a Festo PAM, a pair of on-off valves driven by pulse-width modulated signals, and sensors for PAM displacement and pressure. Controller performance is tested using several dynamic position tracking tests, and the results are compared to an equivalent linear controller. The gain-scheduled approach successfully counteracts the differing inflation / deflation dynamics of the system, showing improved tracking performance over the linear controller with considerably less variability due to operating region.

Original languageEnglish
Title of host publicationProceedings of ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021
Place of PublicationU. S. A.
PublisherThe American Society of Mechanical Engineers(ASME)
Number of pages6
ISBN (Electronic)9780791885239
DOIs
Publication statusE-pub ahead of print - 13 Dec 2021
EventASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 - Virtual, Online
Duration: 19 Oct 202121 Oct 2021

Publication series

NameFluid Power Systems and Technology
PublisherASME
ISSN (Print)1096-6455

Conference

ConferenceASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021
CityVirtual, Online
Period19/10/2121/10/21

Keywords

  • Gain-scheduling
  • Non-linear control
  • Pneumatic artificial muscle
  • Pneumatic muscle actuator

ASJC Scopus subject areas

  • Fluid Flow and Transfer Processes

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