Object Avoidance and Lane Departure using Cheap RC car

For our project we want to make an object avoidance and lane departure warning system. We are using an ultrasonic sensor (hcsr04) for the object avoidance system and managed to stop on the set distance. We have also slightly managed to accelerate and decelerate the RC car if it is getting away and nearer to an object. What we want to do next is to be able WARN(in our project to light an LED or create and audible alarm) whenever the RC car crosses a line (white or black line ).

From this page:
http://www.buildcircuit.com/test-your-sensors-for-line-following-robots/

What sensors are better to use for our proposed lane departure warning system ? We have seen many lane following robots but we just want to be able to detect a line and warn ( light an LED) for our system. If we would be able finish that, our next step would be to detect a line, and turn away ( avoid) the line.

I will update soon (i will post some pictures if requested ) and I am open to accept your suggestions and help. Thank you in advance and more power to all!

Either of the methods on that page (ldr or ir photodiode) will probably be ok. Some people say ldrs are slow but aparently that's not really the case for this type of use. The components are cheap enough, so buy a couple of each and try them on the lines you need to detect.

Paul

Thank you for you reply Sir Paul. The methods on the link proposes to follow the line when it detects one, we want our RC car to light an LED when a line is detected (for the mean time) and be able to go back to it's lane (what we really want ). Can you please educate me more if you have time to spare ? Thanks

hakunamatata:
Thank you for you reply Sir Paul.

“Sir Paul”? Wow, I’ve never been called that before! Not everyone from England is a Sir, you know. Paul will do.

I’m not an expert on line-following detectors, but I know that the tricky part is detecting the line. What your program then does, lighting a led, or steering a car, is up to your skill as a programmer. The line detection circuit is the same in either case.

The more information you can give, the better the quality of help you will receive on this forum. Links to information, such as data sheets, are especially useful.

Paul