Post by thread:Surveying. (sas: Extra GPS receivers?)

Sorry about the double post. Itchy trigger finger :) Adam, Let's go back to original problem. We want to map a trail. Let's assume that we've got a 7.5 minute topo map. On CD, if that helps. Can I do inertial navigation, by integrating the output of a bike speedo and the output of a digital compass using the PIC as a data logger, and post processing? How about a special pickup using the bike wheel as a distance measurement wheel, and the compass? How about Loran, which is not intentionally crippled? How about just good old fashioned orienteering / surveying methods by triangulation to known fixes? Is there an advantage to having a smart data collection system to do calculation on the fly?

Barry King wrote: > Let's go back to original problem. We want to map a trail. Let's > assume that we've got a 7.5 minute topo map. On CD, if that helps. > > Can I do inertial navigation, by integrating the output of a bike > speedo and the output of a digital compass using the PIC as a data > logger, and post processing? How about a special pickup using the > bike wheel as a distance measurement wheel, and the compass? I've thought about that, but I don't know any inexpensive digital compasses which would give me, say 1 degree of resolution and accuracy. Secondly, I'd then need to find altitude seperately. I've thought about simple measuring the angle of the front wheel in relation to the rest of the bike, and the distance it travels, but, again, altitude becomes a problem, and I shudder to think about the math involved. Altitude matters only because if I go stright, turn right, go down a hill, and turn right again to end up at the beginning, I will end up with a map where the end is nowhere close to the beginning, even though they are the same point. The distance going downhill is not directly translated into forward movement. (ie, 15 feet of wheel movement, and I may have only moved horizontally by 10 feet) I could have a tilt sensor, but that is an added variable to the entire equation which is neatly solved with GPS. > > How about Loran, which is not intentionally crippled? Haven't thought about it much. It's not considered inexpensive to me. I imagine I does not give altitude... > > How about just good old fashioned orienteering / surveying methods by > triangulation to known fixes? Is there an advantage to having a > smart data collection system to do calculation on the fly? Yes, I'm only doing this for fun, as part of a hobby. I don't want to survey the trails, I want to measure my performance, and see a map of where I was, and how I did on any given trail. So I would rather spend an hour biking the trail and have the data at the end, than going out with equipment and surveying the trail. -Adam

Barry King wrote: > > Sorry about the double post. Itchy trigger finger :) > > Adam, > > Let's go back to original problem. We want to map a trail. Let's > assume that we've got a 7.5 minute topo map. On CD, if that helps. > > Can I do inertial navigation, by integrating the output of a bike > speedo and the output of a digital compass using the PIC as a data > logger, and post processing? How about a special pickup using the > bike wheel as a distance measurement wheel, and the compass? > Certainly for enough money you can get a dead reconning system to attach to a GPS receiver, and they do improve accuracy. I don't know aobut vibration. A mountain bike is not a stable platform. > How about Loran, which is not intentionally crippled? Don't think it's as accurate as GPS. Loran was intended as a long range navigation system. Have you verified that you actually do have an accuracy problem with simple USCG corrected GPS? -- Anniepoo Need loco motors? http://www.idiom.com/~anniepoo/depot/motors.html