[GlennGraham]

Short update - I'm having fun with the ultrasonic sensor but I'm surprised at how long it takes to get a reading. I've mounted the sensor on a axle which is turned by a servo motor like the old WWII radar dishes. I pan it through 180 degrees measuring the bearig and distance of the closest echo measured. It can pick up a liter pop bottle at about 2 feet away pretty well but its range drops off quickly for anything smaller or less solid. To scan without gaps it needs to take readings at about every 15 degrees. Just stepping through the locations without taking readings is pretty quick (a second or two) but when taking readings it pauses noticeably at each point so the scan takes around 8 - 10 seconds. It can find and approach a stationary pop bottle but wouldn't keep up with someone walking a couple of paces ahead or a slow moving robot. Oh well, it will still have its uses but not for what I was hoping for. If anyone figures out how to get better performance, please let us know.