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LPS

Local Positioning System
 
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I keep running into situations where it is difficult to reach into or around corners with a tape measure or a ruler. The LPS consists of two units and works similar to the GPS. One unit is a transmitter with an array of antennas that sits somewhere in my basement. The second unit is a small portable receiver. I take it to a point in my house and hit the "Start" button. Then I take it to a second point and hit the "End" button. The display shows me the distance between the points. It also indicates if the points are vertical above each other or horizontal side by side.

When several people work on projects they need only one transmitter, but each needs a separate receiver. Since the receivers are passive devices they can measure without interfering.

If GPS is good for a few meters using satellites hundreds kilometers away then LPS should be good for a few millimeters in my house. Perhaps someone can come up with a smart way to use signals from local cell phone towers instead of the antenna in the basement.

kbecker, Nov 21 2003

Baked http://www.memagazi...surng/measurng.html
Boeing uses local GPS [Worldgineer, Oct 05 2004, last modified Oct 21 2004]

Constellation 3di, the system used by Boeing http://www.constell...n3di.com/indoor.php
+- 0.050 mm, according to the manufacturer's web site [Worldgineer, Oct 05 2004, last modified Oct 21 2004]

[link]






       [UB] (1) How much lumber will I need to build that deck? Oops, can't measure straight with that brush in the way. Get chainsaw, clear area, measure, leave a wasteland until deck is in place.   

       (2) Where is that stud I need for mounting the new kitchen cabinet? Oops, stud finder doesn't find it. But I can see it where the 2x4 starts in the basement. Would be nice to be able to find a point directly above the start, but a plumb line doesn't work through the floor.   

       (3) For a level curtain rail the mounting holes in the wall must be at the same height! Oops, water level is too short, window frame gets in the way of laser level. Get hose, fill with water find height, spill water, mess up wall paint.   

       (4) Hey you, can you hold down the end of that tape measure for me? - Naa, I'm on lunch break. - F*** you just hold it down -- compare to LPS: hold to first point and push "Start", hold to second point and push "End"   

       (5) How much wire do I need to route that phone line around all those corners? Unroll tape and measure first leg, retract tape and measure second smaller leg, extend tape and measure ... -- compare to LPS (Delux model): hold to first point and push "Start", hold to second pointa nd push "Add", hold to third point and push "Add", ...   

       Conclusion: The world would be a better place with LPS.
kbecker, Nov 23 2003
  

       (6) Creating a CAD design of an existing structure (room/deck/house). An LPS that could upload the coordinates back to a computer would kick serious rump.
I've played with ultrasonic tape measures, and seen laser sights in action, and in this application LPS would blow the socks off both of these.
benjamin, Nov 23 2003
  

       I'll take benjamin's word for it, though I'm wondering why you're not using any carpenter's tricks.
thumbwax, Nov 23 2003
  

       [UB] That's real life, as far as real life still exists outside the internet; but I think [benjamin]s application should be at the top of all reasons.   

       [benjamin] do you have any venture capital at hand? We have 1 year to patent this.   

       [thumb] What carpenter's tricks? The only trick I have seen them do so far is "Buy more than you may ever possibly need for this project and charge it to the customer" Take the leftovers and build your own nice mansion.
kbecker, Nov 25 2003
  

       I have an application for this. I also have half-baked a solution at one point in time. However, I think that a patent would be difficult to get. By your own admission, LPS is "similar to GPS".
  

       LPS should have 3 or 4 units: a Base unit, connected to a PC; 1 or 2 Reference units; and a Handheld Remote unit. The measurement principle could be radio triangulation. Also required is a calibration routine, and a simple protocol for data transmission between Base and Remote.
xrayTed, Nov 26 2003
  

       [benjamin] I have seen a prototype software/camera package that does exactly that for largish plantrooms and buildings. It takes a picture of the pipes and other services in a plantroom and converts the image to a coordinated AutoCcad drawing.
It could be going somewhere. I am not sure as to the resolution though.
gnomethang, Nov 26 2003
  

       You could do all of the listed tasks with a theodolite (sp?) or laser level and tripod. But LPS would be faster and simpler, though it might irritate surveyors. So don't come running to me when you find a scale drawing of a horses head in your bed. (+)
chud, Nov 26 2003
  

       There was an article in Mechanical Engineering magazine earlier this year. See link.
Worldgineer, Nov 26 2003
  

       Use those triangulators that they use for robotic soccer games.
RayfordSteele, Nov 26 2003
  

       I don't think this would work very well. A GPS receiver knows where it is by measuring very small phase differences between signals from three or more satellites, each one equipped with an atomic clock. Atomic clocks are expensive, so putting the equivalent of three GPS satellites around your house wouldn’t be an option.   

       Your best bet would be to use differential GPS, which uses a stationary receiver to measure and correct for the error in the GPS signal. It would probably give you accuracy of a few centimeters in the horizontal plane, which would be fine for measuring cable, but not for carpentry. In most cases you wouldn’t be able to use it indoors or near large buildings since you need to have a line of sight to the satellites.
AO, Nov 26 2003
  

       All this requires is two GPS units and some software to interpret the signals.   

       If I may make a distinction between precision and accuracy, accuracy would be hitting somewhere within 6 inches (spread evenly) of the bullseye when shooting from 1000 yards. Precision would be hitting two feet away from the bullseye, but in a 1-inch group.   

       GPS has precision, but lacks the accuracy, due to slight variations in the orbits. If you place one unit in a fixed known location, you can easily compute the error. You can find the exact location of the second unit by applying this error correction to its reported location. If this error were constant, you could get the precision without the accuracy by using a single unit, but since the error varies with time, you need a constant report, and thus the fixed unit. If you don't care about exactly where you are, but you still want the precision, you can still use the two units, but inputting the exact location of the fixed unit isn't critical.   

       This is widely baked, it's called "Differential GPS" and is accurate to a fraction of a centimeter when in the vicinity of the fixed unit.   

       While the technology is fully baked, I'm going to croissant this, since it would be nice to see something like this in my handyman's toolbox. A contractor could get away with one base unit (set it on a tripod at the jobsite) and several recievers for all the workers.   

       A handheld unit could incorporate features such as a built-in studfinder, and the locating features could be used as a level indicator. With two units (one at each end of a long beam, for instance), you could get really accurate leveling information. I think the patent would apply more to the implementation than the actual technology, so big fat buttery flaky croissant for you.
Freefall, Nov 26 2003
  

       Looks like [World] hit on something (link). That leaves only baking this for the low end market and implementing the features that the common resident or building contractor needs. Looking at all the gadgets at HomeDepot that could be replaced by such a system there may be a huge market.
kbecker, Nov 26 2003
  

       get up and get after it
bss, Jul 09 2004
  

       I like it. Perfect for when i'm cleaning my room and i get lost. (+)
schematics, Jul 09 2004
  

       I'm in the middle of remodelling my bedroom and one of the difficulties I hit early on was that, like every other room in the (140 year old) house, there are no right angles and no vertical walls. The room is basically rectangular but opposite walls are neither parallel nor the same length. This idea would have helped.
angel, Jul 09 2004
  

       i could use this.   

       CAD is great
DesertFox, Jul 09 2004
  

       A sure fire winner. While the Boeing system does much the same, it looks like a million dollar investment. You on the other hand seem to be proposing a cheap equivalent accurate to within 1mm over domestic ranges. As far as I can see you would need a minimum of four units - three transmitters that you could triangulate from and one receiver - probably easier if you had three antenna coming from one 'brain'. If you were to get the system accurate and ensure that it could calculate height differences properly, you would have to lay out the transmitters accurately and level them with a spirit level or equivalent. You would also have to calibrate it. As such, it would be a bit of a hassle to use, however if the system was available for £200-ish ($400-ish) it could be a very worthwhile investment at the start of a new build or renovation project. Big, fat croissant (and a coffee too if you ever build it).
wagster, Jul 09 2004
  
      
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