Development of an active cable-driven, force-controlled robotic system for walking rehabilitation

Fang, Juan; Haldimann, Michael; Marchal-Crespo, Laura; Hunt, Kenneth James (2021). Development of an active cable-driven, force-controlled robotic system for walking rehabilitation Frontiers in Neurorobotics, 15 Frontiers Media SA 10.3389/fnbot.2021.651177

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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.

Item Type:

Journal Article (Original Article)


School of Engineering and Computer Science > Institut für Rehabilitation und Leistungstechnologie IRPT
BFH Centres > BFH centre for Health technologies


Fang, Juan;
Haldimann, Michael;
Marchal-Crespo, Laura and
Hunt, Kenneth James


T Technology > T Technology (General)




Frontiers Media SA




Juan Fang

Date Deposited:

20 Dec 2021 15:29

Last Modified:

20 Dec 2021 15:29

Publisher DOI:





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