I'm looking at the feasibility of building a field striping robot. For now I'm not concerned with getting the actual stripe on the ground, but rather how to set up a robot to draw a very straight line to a very specific waypoint. The line could be anywhere from 10 to 100+ yards long and on a moderately rough outdoor field.
As far as I know, GPS isn't accurate enough, even though there are commercial units that claim to be GPS based. A compass may work, but I would need to know the exact angle the line needed to be drawn.
Is this for painting lines on a football field (or similar)?
How much deviation either side of the desired line would be acceptable +/- how many centimeters?
Can you place a marker at the opposite ends of each particular line?
Or could you place a number of markers (at least 3) around the boundaries of the field so that the robot could take its bearing from them?
Apart from the difficulties of getting its bearings the robot may also face physical difficulties in holding a course if the terrain is rough. What size will the robot's wheels be and how much will the whole thing weigh? (Bigger is probably better).
It's for an archery field but it is the same idea as a football field.
A deviation of +/- 5 centimeters would be ideal, but +/- 10 or 15 would work. One set of parallel lines is for marking target distances, with the shortest being 10 meters. The crossing lines are used to mark shooting lanes, so they are not critical.
I could place as many markers as necessary for the robot to get its bearings.
The terrain is not too rough. It is mowed grass, but mowed shorter in some locations than others. Occasionally there may be a shallow depression in the ground. It's not a field for actually playing sports on. Just walking back and forth between the shooting line and the target.
I'm not sure what to do next. I think you can get mirrors that always reflect back to the source of light. If you mount one of those on each post and if your robot has a scanning laser it could detect the angle at which it picks up a reflection and use that to calculate its position relative to the posts. (Similar idea to ships using lighthouses at sea).
I've no idea how practical that would be, or whether you would need lasers with dangerous power levels.
Hopefully someone with more ideas will come along.