I have made the project in the link but I do not want to use optical sensors for checking the presense or absence of obstacles. Basically I want to detect obstacles within 2 feet or so but I dont want to use IR, what other options can I try, I want somethign that is rugged.
http://www.ingenstech.com/projects/foot-board-travelling-prevention-system/
http://www.ingenstech.com/projects/foot-board-travelling-prevention-system/