Development of an Active Cable-Driven, Force-Controlled Robotic System for Walking Rehabilitation
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BORIS DOI
Date of Publication
May 21, 2021
Publication Type
Article
Division/Institute
Author
Fang, Juan | |
Haldimann, Michael | |
Hunt, Kenneth J. |
Series
Frontiers in neurorobotics
ISSN or ISBN (if monograph)
1662-5218
Publisher
Frontiers
Language
English
Publisher DOI
PubMed ID
34093158
Description
In a parallel development to traditional rigid rehabilitation robotic systems, cable-driven systems are becoming popular. The robowalk expander product uses passive elastic bands in the training of the lower limbs. However, a well-controlled assistance or resistance is desirable for effective walking relearning and muscle training. To achieve well-controlled force during locomotion training with the robowalk expander, we replaced the elastic bands with actuator-driven cables and implemented force control algorithms for regulation of cable tensions. The aim of this work was to develop an active cable-driven robotic system, and to evaluate force control strategies for walking rehabilitation using frequency-domain analysis. The system parameters were determined through experiment-assisted simulation. Then force-feedback lead controllers were developed for static force tracking, and velocity-feedforward lead compensators were implemented to reduce velocity-related disturbances during walking. The technical evaluation of the active cable-driven robotic system showed that force-feedback lead controllers produced satisfactory force tracking in the static tests with a mean error of 5.5%, but in the dynamic tests, a mean error of 13.2% was observed. Further implementation of the velocity-feedforward lead compensators reduced the force tracking error to 9% in dynamic tests. With the combined control algorithms, the active cable-driven robotic system produced constant force within the four cables during walking on the treadmill, with a mean force-tracking error of 10.3%. This study demonstrates that the force control algorithms are technically feasible. The active cable-driven, force-controlled robotic system has the potential to produce user-defined assistance or resistance in rehabilitation and fitness training.
File(s)
File | File Type | Format | Size | License | Publisher/Copright statement | Content | |
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fnbot-15-651177.pdf | text | Adobe PDF | 3.51 MB | Attribution (CC BY 4.0) | published |