Outdoor Obstacle Detection

[tbr75]

I'm looking for some help with a project. It's an autonomous lawnmower for a competition, and I need it to detect obstacles. The obstacles that are part of the competition are a dynamic obstacle (toy poodle on an RC car), and two static obstacles (flower bed with 6" high black plastic around the edges and a white picket fence). The project has been done in the past at my school, but the sonar sensors they used only worked in detecting the toy poodle.

Apparently the sonar gave false readings because of the grass when mounted to see the flower bed.

Looking for relatively inexpensive solutions (as in, the school won't pay for a $2300 laser rangefinder).

So, in your opinion, what is the best way to detect obstacles outdoors?

 

[dougy83]

So, in your opinion, what is the best way to detect obstacles outdoors?

Personally I'd just use a webcam and analyse the captured frames to tell me what's not grass and decide whether the 'not-grass' is worth avoiding or not.

Obviously the grass has given ranges for colour and texture, while black plastic and white pickets aren't similar to grass in those respects.

 

[Diver300]

Use the ultrasonic reversing sensors from a car. $20 per set from Ebay. They'll need some hacking.