Nonlinear disturbance observer based flexible-boundary prescribed performance control for a lower limb exoskeleton

Yu Wang, Haoping Wang and Yang Tian

International Journal of Systems Science, 2021, vol. 52, issue 15, 3176-3189

Abstract: In this article, a nonlinear disturbance observer based flexible-boundary prescribed performance controller (NDOPPC) is proposed to achieve outstanding transient and steady-state tracking performance for a lower limb exoskeleton. To estimate and compensate the lumped disturbance consisting of unmodelled dynamics and interaction torques applied by the wearer, a nonlinear disturbance observer (NDO) is utilised. The prescribed performance of the trajectory tracking of the exoskeleton is guaranteed by constraining the tracking error between the preset upper and lower boundaries. The boundaries of the proposed NDOPPC can be asymmetric functions in various forms, which increases the flexibility of the prescribed performance. The proposed NDOPPC is designed based on backstepping and the stability is analysed with Lyapunov theorem. Comparative simulations have been conducted with MATLAB/Simulink. Compared to computed torque controller (CTC) and nonlinear disturbance observer based computed torque controller (NDOCTC), the obtained results of comparative simulations demonstrate the effectiveness and superiority of NDOPPC. Finally, different types of boundaries are considered to demonstrate the flexibility of the proposed NDOPPC.

Date: 2021
References: Add references at CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
http://hdl.handle.net/10.1080/00207721.2021.1922952 (text/html)
Access to full text is restricted to subscribers.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:taf:tsysxx:v:52:y:2021:i:15:p:3176-3189

Ordering information: This journal article can be ordered from
http://www.tandfonline.com/pricing/journal/TSYS20

DOI: 10.1080/00207721.2021.1922952

Access Statistics for this article

International Journal of Systems Science is currently edited by Visakan Kadirkamanathan

More articles in International Journal of Systems Science from Taylor & Francis Journals
Bibliographic data for series maintained by Chris Longhurst ().