Instrumented crutches with audio feedback to alter assisted gait

The recruitment of Spinal Cord Injury (SCI) users to test exoskeletons for assisting gait must face the limited number of available subjects. Healthy subjects are often involved to ensure a larger sample in the validation and usability tests in preliminary phases, but the reliability of the results is limited. In this paper we propose a method based on audio feedback, driven by instrumented crutches for force measurements, to train healthy subjects to behave as exoskeletons' SCI users, to decrease the discrepancy with real case results. We analyzed 22 able-bodied subjects an exoskeleton in passive mode during a straight walk, in the presence or absence of the audio feedback controlled by the dominant-side crutch. A force threshold to activate the audio feedback before taking each step induces alterations in both the spatio-temporal parameters and the load on the crutches. Learning effects are observed in trials without feedback after brief training with it. Even if the subjects are asked to push symmetrically on the crutches, they pay more attention to the feedback than to the given instructions, causing a load unbalance.