an imageParking meters can be a source of inconvenience for police officers in that oftentimes, the LCD display is foggy or difficult to read. Parking meters often have a default setting that display a red background even when cars are not present. Our project, the Ultrasonic Sensometer, seeks to address these issues by detecting when a car is present at the parking meter and displaying an LED that visible from 10 meters away when lit.

The Ultrasonic Sensometer implements an alert system that detects the presence of a parked automobile within 2 meters. The parking meter sensor is able to determine whether the car is legally parked, overdue, or soon to expire. The Ultrasonic Sensometer receives two input signals from the parking meter: if the parking meter has been paid and if five minutes or less are remaining on the meter. In our demo, these signals are simulated by two external switches. The device will signal the state of the parking meter, overdue or within five minutes, with a light-emitting diode (LED). The project integrates a Parallax PING))) sensor; an Arduino Uno with an ATmega328 processor; and circuit elements including an LED, resistors, and switches.

To conserve energy, the device has a sleep mode which wakes itself up approximately every fifteen minutes. The Ultrasonic Sensometer will run on the parking meter's battery. Future directions involve making a wireless module to alert the parker as well as the police as to the state of the parking event.


Ruth Nan, Sydney Saito, and Kaichen Zhang

ESE 498: Senior Design

Washington University