phillip@cs.uow.edu.au (Phillip McKerrow) (10/25/90)
A few years ago an Australian inventor (Cornelius Gooley of Melbourne) patented an electronic level detection module, made from the glass vial out of a carpenters spirit level. About half the size of a match box, the device consists of a spirit level fitted with 8 light emitting diodes at each end. The diodes produce tiny beams of light which bounce off the sides of the spirit level's bubble and are picked up by four photoelectric cells mounted on the sides of the level ( 2 on each side at +45 and -45 degrees from the top, and about 0.25 of the length of the level in from each end). The photoelectric cells produce a small current proportional to the inclination of the level. Evidently both roll and pitch can be determined from the signal. I believe that the US tool manufacturer, Johnson Level and Tool of Wisconsin include the device in their precision tool products. With a little bit of thought a somple sensor could be made on this principle for use in a low cost robot. Phillip McKerrow Intelligent Robotics Laboratory Department of Computer Science The University of Wollongong PO Box 1144 Wollongong, NSW, 2500 Australia. Seek and you will find, Ask and you will receive. (God in human form)