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. 2012:2012:344-7.
doi: 10.1109/EMBC.2012.6345939.

Enhancing stance phase propulsion during level walking by combining FES with a powered exoskeleton for persons with paraplegia

Kevin H Ha  1 , Hugo A Quintero, Ryan J Farris, Michael Goldfarb
Affiliations

Enhancing stance phase propulsion during level walking by combining FES with a powered exoskeleton for persons with paraplegia

Kevin H Ha et al. Annu Int Conf IEEE Eng Med Biol Soc. 2012.

Abstract

This paper describes the design and implementation of a cooperative controller that combines functional electrical stimulation (FES) with a powered lower limb exoskeleton to provide enhanced hip extension during the stance phase of walking in persons with paraplegia. The controller utilizes two sources of actuation: the electric motors of the powered exoskeleton and the user's machine (FSM), a set of FES. It consists of a finite-state machine (FSM), a set of proportional-derivative (PD) controllers for the exoskeleton and a cycle-to-cycle adaptive controller for muscle stimulation. Level ground walking is conducted on a single subject with complete T10 paraplegia. Results show a 34% reduction in electrical power requirements at the hip joints during the stance phase of the gait cycle with the cooperative controller compared to using electric motors alone.

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Figures

Figure 1
Figure 1
Vanderbilt exoskeleton
Figure 2
Figure 2
State-flow diagram showing the states involved in walking and when hamstring stimulation occurs. Left hamstrings are stimulated in left forward (standing with left foot forward) and left stance (taking a right step). Right hamstrings are stimulated in right forward (standing with right foot forward) and right stance (taking a left step).
Figure 3
Figure 3
Cooperative controller for the Vanderbilt exoskeleton with cycle-to-cycle adaptive FES timing. Hamstrings are stimulated in double support and stance states. The controller adapts the timing of stimulation within each state based on hip torque data from previous steps.
Figure 4
Figure 4
Experimental setup. a) Surface electrodes placed over the posterior thigh. b) Subject walking with the exoskeleton.
Figure 5
Figure 5
Exoskeleton hip joint torque during extension without FES (dashed blue) and with FES (solid red). Thick lines are joint torques averaged over all steps taken. Thin lines indicate one standard deviation.
Figure 6
Figure 6
Exoskeleton hip joint power during extension without FES (dashed blue) and with FES (solid red). Thick lines are joint power averaged over all steps taken. Thin lines indicate one standard deviation.
See this image and copyright information in PMC

References

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