Principle of Operation
OnBoard Unit consists of a GPS which constantly determines the location and speed of the car in which the unit is located. This information is logged by a laptop and sent to the transceiver, which sends it to the Roadside Unit.
The Roadside Unit transceiver receives the speed and location information from the OnBoard Unit. It verifies if the light is turning red anytime soon, and if it is then it calculates whether the speeding car will run the red light. If it will run the red light, then a warning signal is sent to the transceivers of all OnBoard Units.
We are simulating the traffic light on a microcontroller. The microcontroller has an external clock which helps it keep track of the period of time the light should remain a certain color. It is directly connected to the Roadside Unit laptop, to which it sends a control signal defining the point after which the Roadside Unit needs to consider all messages from the OnBoard Unit as Event Messages.
If the speeding car will run the red light, then a warning message is sent from the Roadside Unit transceiver to the transceivers on the OnBoard Units of the speeding car as well as the waiting car.
There are two inputs to the Accident Warning System.
This input contains information on the speed and location of the car in which the GPS is located. It is constantly sent to the Roadside Unit.
2. Traffic Light
This input allows the Roadside Unit to judge when to regard the speed and location information from the OnBoard Unit as Event Messages.
There are two kinds of output from the Accident Warning System.
1. Warning Signal
A warning signal is sent from the Roadside Unit transceiver to the OnBoard Unit transceiver of the speeding and waiting cars in order to warn both cars that the speeding car is about to run the red light.
2. No Action
If the speeding car will not run the red light, then no action is taken by the Roadside Unit and hence no warning signals are received by the OnBoard Units.
The acceptability test is to ensure the successful execution of the real-life demonstration of an accident warning system involving a single speeding car. If the car is about to run the red light, then a warning should flash on the laptops of the speeding and waiting car. If it is not going to run the red light, then no action should be taken.
This page is maintained by Richa Prasad.
© 2007 University of Massachusetts Amherst • Amherst, MA 01003