Development and characterization of a high-spatial-temporal-resolution foot-sole-pressure measurement system

Humans and biped robots generate unique pressure distributions under their feet while standing and walking. These foot pressure distributions are very vital information to analyze balance and walking in humans, and to analyze and control the gait cycles in robots. This research work involved development of a measurement system for measuring foot pressures using the Tekscan's F-Scan foot pressure sensor, characterization of the system and conducting some experiments to evaluate the system and introduce some statistical measures to characterize the pressure maps. The multiplexer and interface electronics were designed and the data acquisition system was built. Then the system characterization including the single sensor and whole sensor calibration was done. The spatial resolution of the F-Scan sensor is about 25 mm2, and the while scanning a single sensor element, the sampling time is about 0.3 ms, but sampling the complete sensor takes about 300 ms. So the issue is, there can be a trade-off between spatial and temporal resolution, reducing temporal resolution will increase spatial resolution and vice versa. The system was later evaluated using an in-house constructed simulation frame, which simulated the loading on an artificial leg, and generated unique pressure distributions for static and dynamic swaying of the leg. These pressure maps were analyzed using method of moments.

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