Is it possible in a field 300x300 to use :
3 RF Transmitters
1 RF Receiver
and get within inches of accuracy in a trilateration calculation?
Or is this a myth?
True in theory but in practice its a myth.
Search these forums for several discussions on details of why.
In a 300m *300m field, practice has indicated you might get within 30K meters!
You would be more accurate just randomly picking a spot inside the bounding box.
Thanks; ok hahaha yeah. I’ve searched the forums and I found Ultrasonic Trilateration is sensitive to the millimeter? But I am guessing due to the nature of Ultrasonic Trilateration that a field of my size will not work. :oops: I’m so stuck I would be glad to contract someone who has done this before over paypal or your choice.
My field : It’s 300x300 ft so roughly 91m x 91m a giant square; perfect for my project.
Assuming I have a near unlimited budget and want to position an object in the field within 1 foot of it’s actual position; what should I use? It’s tracking a large commercial mower FYI so whatever we use will have to be able to work regardless of speed, orientation, bouncing, loud mowing.
Sonar?
IR?
Fixed Position start and Measure the Tire rotations? (IE Dead reckoning?)
Super Expensive GPS? DGPS?
Hire a civil engineer to follow it around at all times?
1 foot : accuracy tolerance
100 meters : The max distance of the receiver to the transmitter (whatever those two may be)
GPS/DPGS are not likley to get you to the foot ALL the time. Based on satelite configuration (ever changing) you can go over this error.
DR will be hopeless after the first turn you make.
Is your arena obstruction free? Can you sync three or more sensor nodes via cables?
If so, I would be tempted to spin laser pointers at three locations at precisely know rates. I would then put a omnidirectional laser receiver on a mast over your bot and receive the pulses. Based on the time of arrival, you can deduce angles and hence position.
Or three cameras on gimbals that track a high reflective target on your bot (or a bright light). If the can center tha camera on the dot, then you know the camra is pointing at the bot. You can now have three angles and do the triangulation.
With infinite budget, a ring laser gyro as part of an inertial navigation unit would work. Heck, with an RLG, you can sense the Earth rotate under you as it spins.
How much can you instrument your field? Could you run wires in a grid under the surface and create a massive “graphics tablet” using EM pulses down the wires?
Running out of ideas.
I love the ideas; is Ultrasonic right out due to range? Max distance would be 100M
I suppose I could sync the three or more sensor nodes; just no wires can go to the moving mower.
Keep in mind it is a mower; would the spinning lasers get lost on a bouncing receiver?
I love the grid but if I get this working I would like to use it in other fields by simply building more transmitters in adjoining fields.
I’d like to be able to get a list of what I need to buy; I’ll get it working and post my findings as I go. If anyone wants to help I wouldn’t mind paying for the virtual time.
often, it's 1 at a time transmitter, multiple receivers, on a baseline.Newduino:
Is it possible in a field 300x300 to use :3 RF Transmitters
1 RF Receiver
and get within inches of accuracy in a trilateration calculation?
Or is this a myth?
Common high precision time reference. (That’s why it’s impractical for hobbyists). Higher precision than GPS timing, to get inches of accuracy.
Time difference of arrival algorithm. Eliminate the ghost solution by some means like a priori or direction of arrival rough estimate.
RTK mode of GPS gets sub-one-inch, but not practical for things that move.
stevech;
Any chance you know the components needed to get inches of accuracy?
I’ll buy them and set it up; providing full source/project info as I do it.
It’s a little pricey but think I’d get inches of accuracy with this ?
Newduino:
stevech;Any chance you know the components needed to get inches of accuracy?
I’ll buy them and set it up; providing full source/project info as I do it.
Some vendors I’ve worked with in the professional arena:
Ekahau
Wherenet
Aeroscout