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As part of the investigation into device free localization of subjects, I developed a capacitive sensing floor. The underside of the floor has a grid of 10 cm by 10 cm (approx.) conductive squares, which are wired back to a microcontroller. The microcontroller constantly samples the capacitance of the squares, and from this can detect the presence of a human subject. The floor can position a subject’s foot to withing several cm and is able to estimate a subject’s trajectory from successive footprints. An HTC Vive VR tracker was used as a ground truth to check the estimated positioning of the subject from the floor.

The PCB (custom made using Altium) uses an STM32f103 microcontroller which was programmed using system Workbench for STM32. The PCBs can communicate over Wi-Fi (using an esp8266) or USB; and are powered over USB. A PC app was made using JavaScript and Electron. Several other low level NodeJS scripts are run in parallel to act as a bridge between the USB serial ports and the PC app which expects data to arrive via http.

More details can be seen in the conference paper [here] and the journal article [here].