"I understand. I'm just replacing rotation with modulation. Less mechanical complexity." I'm thinking 'pancake stepper motor and mirror' myself - mirror at 45 degrees from vertical in the downward direction with the IR LED pointing straight up. Would kinda look like the old Ma Bell 'horn-style' microwave dishes. Angular position/rate could be controlled - the 'rate' could even be down to a few hertz ... an index would clue the stepper controller (a PIC, of course) as to say, north - then step from there ... Either that or a crude 'phased array' composed of multiple IR LEDs 'strobed' around a rim of a plate where they would be mounted. I would control them by slowing 'phasing' on two (maybe more) LEDs at a time and allow a gradual 'sweep' all the while sampling for the 3 dB point of the scanning beam by the bot. At this point I don't know who focused IR LEDs are - this would play (obviously) a major part in how this last idea would pan out. Jim ----- Original Message ----- From: "David VanHorn" To: Sent: Friday, August 31, 2001 1:36 PM Subject: Re: [EE]: - Botboard - Yard navigation/mowing pattersn through Yard/VOR system > At 01:19 PM 8/31/01 -0500, Jim wrote: > > "Why rotate?" > > > >Consider a lighthouse - concentrate your radiated energy. > > Likely not needed. Narrow pulses, relatively infrequently, they could even > be coded, as opposed to just at different frequencies. We don't have a > screaming need for speed. > > > > "If you see one, you're still out of the yard." > > > >Now I'm getting confused. You should always be > >seeing *all* your beacons (otherwise you can't > >navigate). IOW - this is a disallowed state. Also, > >I *did* mention a perimeter wire in conjuction with > >this approach ... > > Only if your yard is a single rectangular plot with no trees. > I have three rectangles, connected by a wide path. The back yard beacons > would not be visible from the front yard, except along the walkway. > > XXXXXXXXXXXXXXXXXXX > XXXXTXXHHHHXXXTXXX > XXXXXXXHHHHXXXXXXX > XXXTXXXHHHHCCCCCC > XXXXXXXHHHHXXXXXXX > > H is house, T is tree, C is Concrete, and X gets mowed. > > > >I see how this relates. Again, a seeing eye or sensor > >that can resolve angular bearing. But - how do you > >know which beacon is *which* beacon? > > Either a different rep rate, or a different code. > > > >A VOR 'range' station works on the principle of > >providing user equipment the ability to determine their > >'angle' or bearing to the station - regardless of what > >that bearing may be. Fixes from two (or more) VOR > >stations fixes your positon. Additinally, each beacon \ > >would either 'rotote' at different rates (to distinguish > >them) or modulated at differing rates (i.e. 25 and 30 KHz). > > I understand. I'm just replacing rotation with modulation. > Less mechanical complexity. > > I'm thinking along the same lines I think for raster scanning. All you > really need is to periodically check the beacons to make sure you are on > course. When you hit an end point, you make your turn, verify the beacons > are where they should be, wiggle till that's true, then mow for a while. > Check the beacons maybe every 10' or less, and if things aren't exactly > straight, well I'm not exactly straight either when I do it. > > I have one other complexity, on the side where the long thin part is, the > front yard slopes about 30 degrees across the mow path. Steering will be > interesting. > > Thinking on this a bit, what if Mr Bot has two crab-like eyes, which he can > lock onto a given pair of beacons. A little hardware to keep them in lock, > and the angle between them then tells position immediately. The eyes would > be smart enough to stay locked to a given beacon on their own, until told > to aquire a new beacon. > > > -- > Dave's Engineering Page: http://www.dvanhorn.org > > I would have a link to http://www.findu.com/cgi-bin/find.cgi?KC6ETE-9 here > in my signature line, but due to the inability of sysadmins at TELOCITY to > differentiate a signature line from the text of an email, I am forbidden to > have it. > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics