Traffic light control with Javelin Stamp

Claud

Hi,

I need some advice and ideas. For my school project, we intend to make an intelligent traffic light system which cordinates traffic from a dual carriage on to a single lane which has a lot of traffic on it· using· a sensor to determine if there is enough distance ahead to let the GREEN light show. We plan on using the Javelin stamp as the microcontroller which will be connected to the Traffic lights and the Sensor. My first problem is how to connect the Javelin stamp to the traffic lights because of the different voltage ranges.... Would I need a relay to do that? and what kind? is the Stamp PLC a good choice considering we would have it out doors And I was thinking an Ultra Sonic Sensor to sense vehicles ahead would be a better choice? and which type should I get?. My main problem is how to connect them to the javelin stamp. . Help and suggestions are welcome.

Thanks

Claud

allanlane5

I highly recommend looking at the Parallax documentation on BS2 interfacing. These are in the Analog and Digital class, as well as in the Nuts&Volts article area. Interfacing BS2 hardware is identical to interfacing the Javelin hardware (except for the code, of course).

For the lights, you'll need a transistor driving a relay (unless you get really low-current relays). Another option is an optical-isolator chip of some kind.

In 'real' traffic situations, they use loop-detectors embedded in the roadway. These sense the effect a car's mass of metal has on the magnetic field generated by a loop of wire. You could use IR LED + Sensor, Ultra-Sonic sensors, weight sensors, etc. I believe the range of an ultra-sonic sensor will be a problem -- it sounds like you need a radar-detector (RF) type of range.

In railroad applications they simply use 'occupancy detectors'.