Hi Werner

You could use ultrasonic sensors. You can find interfaces for pics I think
in dontronics site, to allow the measurement of the distance: a tone burst
of 40kHz is generated with a 555 or with a pic and a tone decoder as the 567
detects the reflected wave front.The time delay is proportional to the
distance if the delay introduced by the tone decoder reaction could be
ignored.
Regards

Fernando

-----Original Message-----
From: Werner Soekoe <wsoekoe@GLOBAL.CO.ZA>
To: <PICLIST@MITVMA.MIT.EDU>
Date: Segunda-feira, 20 de Mar¨o de 2000 14:08
Subject: Wall Detector for Mobile Robot


>Hi
>
>Can anyone help: I'm looking for a circuit to be used to sense walls and
>solid objects with for a mobile robot. I though of using optics, but what
>will happen when you paint your
>walls black???
>
>Any help/circuit will be appreciated.
>
>Thanks
>Werner Soekoe
>wsoekoe@global.co.za
>