Human-exoskeleton interaction portrait.
Mohammad Shushtari, Julia Foellmer, Arash Arami
PMID 39232812WHAT IT FOUND
A new 'interaction portrait' metric shows how users adapt to exoskeletons.
In able-bodied walkers, an adaptive controller reduced effort and disagreement, encouraging active movement. This suggests it suits rehabilitation, while a hybrid controller led users to yield control, suiting power augmentation.
Key findings
01The adaptive model-based torque controller (AMTC) significantly reduced metabolic cost and human-exoskeleton interaction torque compared to a time-based controller, indicating less physical disagreement and effort.
02The interaction portrait analysis revealed that users yielded control to the exoskeleton with the hybrid torque controller (HTC), whereas they actively contributed to motion with the AMTC.
03Adaptation strategies varied by body mass, with lighter participants tending to lead motion and heavier participants tending to passively follow the exoskeleton.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was conducted only on nine able-bodied participants, so the findings may not apply to patients with motor impairments such as stroke or spinal cord injury. The exoskeleton weight (approx. 17 kg) added significant load, which may have influenced muscle effort and adaptation strategies differently than in a lighter clinical device. The controllers were not calibrated to individual body mass, which the authors note may have affected the interaction strategies observed. The study used a novel, unvalidated metric (Interaction Portrait) that requires further testing in clinical populations.
Declared interests
Funded by New Frontiers in Research Fund, Canadian Foundation for Innovation, Ontario Research Foundation, and Natural Sciences and Engineering Research Council of Canada. No commercial conflicts of interest were reported.
The easy way to misread this
Do not assume these controllers are ready for clinical use or that the 'adaptive' controller will work the same way for patients with neurological impairments. The study was done on able-bodied people, and the new metric has not yet been validated in patient groups.