How can my robot measure a distance away?

[Tranq97]

I designing a bipedal robot, but I want it the be able to walk off and onto a kerbside properly. So my idea is to put something on the bottom of it's feet of which will measure it's distance to the floor. That way, my robot will know if the ground level has inclined or declined and adjust accordingly. But please can I have a real description of how I could do it. Obviously I've looked up sonar, but I'm not really sure how I would build such system. I'm open to any idea as long as it would work. Thank you!

[jwatte]

I would put a distance sensor on the belly, pointed diagonally down. A "ping" style ultrasonic sensor, or a "sharp" style IR distance sensor would both probably work -- I think I'd prefer the Sharp for this application.

[Tranq97]

Thanks, Ill search them up on Google to find out some more information.

[knossos]

I agree that Sharp sensors would probably best for you.  To augment the sharp sensors, you could also attach a switch to the bottom of the foot so it can detect when the foot actually contacts the ground.

[Joxman2k]

Personally I would use Photocells in the toe and heel regions. They can be covered with clear acrylic to protect them. This would solve for an incline as well. I don't think distance is essential. If the light level has not decreased sufficiently after so much movement, then there is likely a problem, like a CLIFF! The algorithm is move your foot until you sense ground, then stop, determine if it is solid, then continue to move the other foot as you walk.

Pseudo code:
Move FootDown until
ToeCell AND HeelCell equals no light
THEN stop FootDown

Do you plan on using Inverse Kinematics in your programming?