This project is a collaboration with Younjin Song, Sairanjith Thalanki, and Andrew Ge. It was supported by Robotics@Berkeley as part of their annual DXM Robotics Competition.

App

• Users name each platform in the app depending on the item it is tracking
• To setup an item, Re.Stock takes a calibration reading of the platform while empty. Users then place on the item and specify how full it is
• Users adjust the percent of the item left at which they receive a notification. Setting the level higher can account for the weight of the item's packaging
• The app compares each reading to the empty platform calibration reading so it can ignore data taken when the item is not on the platform

Hardware

• Box and platforms built from birch plywood, finished with spray lacquer
• Each platform is attached only to a load cell underneath
• Load cells secured to wood using tee nuts and machine screws

Electronics

• Each load cell is connected to a HX711 amplifier board, which reads the voltage signal from the cell and converts it to a digital signal read by an Arduino
• Amplifiers receive a 5V power supply, a shared ground, and a clock signal from the Arduino
• Arduino takes periodic readings from the amplifiers and passes on the data to the ESP8266 WiFi Module
• Entire system is powered off a 5V power supply connected to the Arduino

Programming

• Data sent to ESP is passed on to a database hosted online using PHP
• App uses HTML parser to pull data from the webpage