A data acquisition system that uses signal scavenging to detect activity on floor pads

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] We designed a data acquisition system to scan data from four sensors on a pad using the smart carpet technology. We constructed and tested four data acquisition systems to read the data, process it, and store it. The data acquisition systems sends the data of active sensors either by plugging directly into a computer through the serial UART port, or wirelessly using a Wi-Fi chip, Spark Core, to the cloud. If we use the Wi-Fi implementation, our system sends notifications either by email, phone call or message text to caregivers when steps on the pad occur. We used microcontroller PIC18F4455 to read the signals from the four sensors on the pad, and process the data. This chip is small, less power consuming, and easy to set up and use. To test the design entirely, we started our work with a breadboard, and then we built our design in printed circuit board. We did several experiments to make our system able to work accurately. We measured the noise value in the pad's sensors to find the threshold value, which helps us to distinguish between the noisy sensors and active sensors. We did another experiment to show its accuracy in counting steps. A major rationale for this effort is to help caregivers track people in critical locations including buildings, bathrooms, exit doors, and around hospital beds. Also, for security purposes the system can detect unauthorized entry through windows.