Observations on the F-Scan in-shoe pressure measuring system

Abstract

OBJECTIVE: To evaluate the physical characteristics (durability, calibration, creep and hysteresis) and the accuracy and repeatability of the F-Scan in-shoe sensor. DESIGN: Observations of the system in clinical use combined with material bench-test experiments. BACKGROUND: The F-Scan system is a commercially produced in-shoe force/pressure measurement system. Whilst useful clinical studies have been reported there is little information on the performance characteristics of the system. METHODS: Output mass error following calibration was directly measured from the F-Scan system. A jig-mounted force meter tested groups of individual sensing units (4 @ 1 cm(-2)) for within and between sensor accuracy in full size and adjusted sensors. An Instron servohydraulic materials testing unit was used to evaluate creep, hysteresis and the repeatability of output forces over repeated loading cycles for full size and cut sensors. RESULTS: The F-Scan system lacks durability and suffers significant calibration error. Creep (19%) and hysteresis (21%) properties were poor. Within and between sensor variability in output was demonstrated and overall repeatability was poor. Adjusting the sensor size adversely affects output. CONCLUSIONS: Our findings suggest the F-Scan system has a limited capability for absolute accuracy but could still be used for quantitative studies provided its limitations are noted. RELEVANCE: These findings may help F-Scan users evaluate the relevance of clinical data and refine measurement protocols in the context of their own field of work.

Ground reaction forces and plantar pressure distribution during occasional loaded gait

“…The Pk data were calculated to absolute (Abs) and normalized (Norm) values. Thus, the follow dependent variables were calculated: medial RF (PkRFMed_Abs, PkRFMed_Norm and PkRFMed_Time); central RF (PkRFCt_Abs, PkRFCt_Norm and PkRFCt_Time); lateral RF (PkRFLat_Abs, PkRFLat_Norm and PkRFLat_Time); medial MF (PkMFMed_Abs, PkMFMed_Norm and PkMFMed_Time); lateral MF (PkMFLat_Abs, PkMFLat_Norm and The in-shoe pressure system presents good information about relative distribution of plantar forces while their absolute values have been questioned (Nicolopoulos et al, 2000;Rosenbaum and Becker, 1997;Woodburn and Helliwell, 1996). The force plate is considered the most accurate dynamic measurements of force (Cobb and Claremont, 1995): thus, the force plate was used to calibrate (post-test) the plantar pressure data test by test.…”

A spectral density approach for modelling continuous vertical forces on pedestrian structures due to walking

“…Some improvement on this approach could be obtained using movies or video recordings of human motion (Winter 1990;Forner Cordero et al 2002). Devices for direct measurement of forces during walking have been developed, for example, in the form of in-sole pressure sensors (Woodburn and Helliwell 1996;Barnett et al 2001;Razian and Pepper 1998).…”

Validity and repeatability of three in-shoe pressure measurement systems

“…The loading characteristics of the Medilogic in-shoe system have not been considered in publications. The Tekscan system has been reported to have low durability and to demonstrate significant creep and hysteresis, high variability between and within sensors and low overall repeatability [8].…”