Olin Library Seat Tracker

Sophie Jacobson and Brooke Johnson

Department of Electrical and Systems Engineering


The objective is to develop a system that indicates to students the status of seats in the library, occupied or unoccupied. A pressure sensor is attached to the cushion of a chair. The pressure sensor is connected to a blue-tooth enabled microprocessor, which communicates with a main station computer. Using Processing programming language and web interface, a connected seat will either appear as green, indicating that it is unoccupied, or red, indicating that it is occupied. This system will ultimately be expanded to include each chair of each seat in the Olin Library.


Every day, students spend time and energy searching for a seat in their University library. Not only do they have to take the time to walk over to the library from their dorm rooms only to find out that all the seats are full, but they must also traverse the floors looking for a seat. The idea for a solution to this problem was generated based on techniques used in parking garages.


Students would benefit from a system which:
  • Tracks the status of library seats
  • Posts seat statuses online in real-time
  • Is compatible with an already constructed library
  • Uses wireless technology without interfering with the pre-existing Wi-Fi in the library


A pressure sensor is utilized to indicate whether or not a person is currently sitting in the seat. A Bluno, which is a development board made from an Arduino Uno, with an Atmega 328 microprocessor and a Bluetooth enabled Texas-Instrument (TI) microprocessor, reads the output from the pressure sensor. The status of pressure sensor attached to the Bluno is reported using Bluetooth to a central Bluno, the base station. This status is displayed on an interface as either a green, available, or red, unavailable, seat. In the ultimate design, only the Bluetooth enabled TI microprocessor would be used, instead of the entire Bluno system, to cut power consumption with unnecessary elements on the board. Additionally, solar cells would be used to power the system.


Diagram of Test System Implementation

This image displays how the system is implemented at each chair. In the final design, the Bluno development boards with be replaced with Bluetooth enabled TI microprocessors.

Bluno 1

Central and Peripheral Bluno Setup

The peripheral Bluno, connected to the pressure sensor, communicates wirelessly to the central Bluno, connected the computer.


Peripheral Bluno system with pressure sensor attachment

IV curve

Characterization of Solar Panel

This chart displays the characteristics of the solar cells used to power the system. The solar panel is made of 8 solar cells. Maximum power is achieved at about 4.25 volts. The maximum current from these solar cells is about 100μA. One solar panel provides enough power to operate each peripheral unit.

Processing Display

Occurred versus Unoccupied Seat

This image displays the current visual interface of Olin Library Seat Tracker. This interface was created using Processing code.

Cost Analysis

Cost Analysis

This analysis considers 1,000 seat units and 3 base units. The 3 base units will be placed on each of the main floors of the Library.



This image shows the future of the visual interface for the seat tracker. Ultimately, the tracker will know the status of every seat, on every floor of the library and display the statuses in a map.

Future plans for the Olin Library Seat Tracker include:
  • Creating a dynamic web-page that continuously updates the status of seats
  • Implementing the technology in Olin Library
  • Marketing the product to other university libraries