Abstract
Measurement of the ground reaction forces (GRF) during walking is typically limited to laboratory settings, and only short observations using wearable pressure insoles have been reported so far. In this study, a new proxy measurement method is proposed to estimate the vertical component of the GRF (vGRF) from wearable accelerometer signals. The accelerations are used as the proxy variable. An orthogonal forward regression algorithm (OFR) is employed to identify the dynamic relationships between the proxy variables and the measured vGRF using pressure-sensing insoles. The obtained model, which represents the connection between the proxy variable and the vGRF, is then used to predict the latter. The results have been validated using pressure insoles data collected from nine healthy individuals under two outdoor walking tasks in non-laboratory settings. The results show that the vGRFs can be reconstructed with high accuracy (with an average prediction error of less than 5.0%) using only one wearable sensor mounted at the waist (L5, fifth lumbar vertebra). Proxy measures with different sensor positions are also discussed. Results show that the waist acceleration-based proxy measurement is more stable with less inter-task and inter-subject variability than the proxy measures based on forehead level accelerations. The proposed proxy measure provides a promising low-cost method for monitoring ground reaction forces in real-life settings and introduces a novel generic approach for replacing the direct determination of difficult to measure variables in many applications.
Highlights
The analysis of ground reaction force (GRF) is central in many scientific and engineering fields, including biomechanics, medical science, sports science, and robotics [1,2,3,4]
Standard measuring techniques for ground reaction forces (GRF) are restricted to laboratory settings, where GRFs can be accurately measured using calibrated force platform systems, but this limits the applicability of the relevant results, which are obtained for one step only
The data from outdoor controlled walking (OCW) and outdoor free walking (OFW) were split into a training set and a test set
Summary
The analysis of ground reaction force (GRF) (i.e., the force of interaction between the body, usually the foot, and the ground) is central in many scientific and engineering fields, including biomechanics, medical science, sports science, and robotics [1,2,3,4]. In human biomechanics and humanoid robotics, for example, postural control is critical for understanding balance and locomotion, where the control. In healthcare, estimating the GRF and joint moments of patients in daily life activities could have substantial clinical impact by providing assessments of pathological gait, fall detection in the elderly, and biofeedback data for home interventions [5,6]. Standard measuring techniques for GRFs are restricted to laboratory settings, where GRFs can be accurately measured using calibrated force platform systems, but this limits the applicability of the relevant results, which are obtained for one step only. Whereas instrumented treadmills with embedded force platforms allow for accurate multi-step GRF measures, they are still limited to the laboratory setting. Some clinical gait features are often triggered by free-living environmental challenges and cannot be replicated in a controlled laboratory environment
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