Preliminary design and testing of a servo-hydraulic actuation system for an autonomous ankle exoskeleton

Viennet, Emmanuel (School of Engineering and Architecture (HEIA-FR), HES-SO // University of Applied Sciences Western Switzerland) ; Bouchardy, Loïc (School of Engineering and Architecture (HEIA-FR), HES-SO // University of Applied Sciences Western Switzerland)

The work presented in this paper aims at developing a hydraulic actuation system for an ankle exoskeleton that is able to deliver a peak power of 250 W, with a maximum torque of 90 N.m and maximum speed of 320 deg/s. After justifying the choice of a servo hydraulic actuator (SHA) over an electro hydrostatic actuator (EHA) for the targeted application, some test results of a first functional prototype are presented. The closed-loop unloaded displacement frequency response of the prototype shows a bandwidth ranging from 5 Hz to 8 Hz for displacement amplitudes between +/-5mm and +/- 20mm, thus demonstrating adequate dynamic performance for normal walking speed. Then, a detailed design is proposed as a combination of commercially available components (in particular a miniature servo valve and a membrane accumulator) and a custom aluminium manifold that incorporates the hydraulic cylinder. The actuator design achieves a total weight of 1.0 kg worn at the ankle.

Note: Due to the COVID-19 outbreak, 12th International Fluid Power Conference venue in Dresden was cancelled. The proceedings of the online conference are however published according to the original schedule.

Conference Type:
published full paper
Ingénierie et Architecture
SeSi - Institut de Systèmes d'ingénierie durables
Dresden, Germany, 12-14 October 2020
Dresden, Germany
12-14 October 2020
7 p.
Published in:
Proceedings of the 12th International Fluid Power Conference, 12-14 October 2020, Dresden, Germany
Numeration (vol. no.):
2020, vol. 3, article no. 10-1, pp. 165-171
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 Record created 2021-01-19, last modified 2021-01-20

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