Library Book Bin Detection System

Engineering 101 Project

Duke Librarians have no system for monitoring the capacity of their book drops: they waste time and energy in over-monitoring the system or lugging back an overflowing book drop bin.

To fix this, I worked with a team of 4 to create an ESP32 bluetooth system to monitor book drop capacity. The book drop bin features a compression spring loaded floor that lowers when more weight is added. Because of this unique geometry, I designed an extended limit switch system for the inside of the bin. These 3 switches remain pressed as the bin lowers, so that the system will be automatically reset when the weight is removed.

This system connects via Bluetooth to an LCD screen on the librarian’s desk that reads capacities: 50% full, 75% full, and 90% full. To determine the proper distances for the limit switches, several tests were conducted to find how average weight of books corresponded to volume, and how this affected the height of the spring-loaded floor.