Obsticle avoidance is quite easy, A rotating mirror, an infra red laser projects a beam, the mirror creats a horozontal line at a specific distance in front of the vehicle, a camera mounded above the laser looks at the terrain ahead useing edge detection the laser line will stand out from the rest of the image and obsticles will apear as breaks in the line.
Everything is available to the homebrewer, scanning mirror from old photocopier or printer, Gameboy cameras have built in edge detection and are easy to use
Google LIDAR