I had another thought today,(I really should be carefull), and that was what if for obstacle detection and sensor input you used three input devices (you pick) then ran the inputs into a comparator circuit. The output of the comparator would then be sent to the CPU or controller device. Statistically this should inhibit the chances of random noises or light from confusing our mechanical friends. Especially if you used three or more inputs and offset the level that the sensors were lined up on. Example use an isocolese (I know that is spelled wrong, but hey it's public education for you!) triangle or hex patern. If you got any thoughts on if this would be a feasible alternative to more exspensive sensors and detection systems... please let me know. jaltop@stmartin.edu

sin jimm