Instrumented crutches with audio feedback to alter assisted gait

Abstract

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.

Validation of Estimators for Weight-Bearing and Shoulder Joint Loads Using Instrumented Crutches

“…These devices also require a postprocessing stage sometimes and cannot provide real-time feedback. While our instrumented crutches may provide gait phase detection, the process still needs to improve the reliability and elaborate data in real-time [25,30].…”

“…The instrumented crutches, shown in Figure 2, measure the force exerted along their principal axis and the crutch's orientation during assisted walking. They are a new version of the previously developed instrumented crutches [23,24,26] in which the control unit is changed, and they also measure the gait phases using depth cameras mounted on the lower part of the crutches [25,30]. A Raspberry PI 3 B+ controls the data acquisition from the strain gauge bridges fixed close to the tip, and the crutch's orientation is obtained by an inertial measurement unit.…”

“…Several research groups have created instrumented crutches because they allow the estimation of the patient's performance during walking and to provide feedback to improve the rehabilitation. The systems developed in [20][21][22][23][24][25][26] measured the force applied to the crutches and their orientation and send the acquired data via wireless communication. For the force measurement, the systems in [21,22] used load cells mounted at the lower end or inside the crutch, while the instrumented crutches in [23,26] used strain gauges to reduce the cost of the device.…”