Inertial Survey System

The irony of a penny being used to scale the size of such a device ... Does it not also scale the value placed on such technology? I mean could someone who has never had to drag a chain through the brush fully appreciate the value of space vehicles and algorithms churning out precise positions in their magical black box? Too deep a thought for me, back to connecting the dots.

Technology has out paced evolution and this is a good example. We don't have any humans yet who are small enough to throw the switches or turn the knobs on that thing.
jud:-/

Many years ago in middle 1960'a, I was employed, in the repair, calibration & testing of of the 25PIGA with the approximate dimensions as shown HERE. This is just one of the three accelerometers, along with the three stabilization gyros, and additional hardware made up the IMU ( Inertial Measurement Unit) of pretty good size.On first impression it is hard to believe it 's miniaturization has come to this, but on second thought, it is not really surprising.

I have been wondering for years. Why this type of tech hasn't hit the survey industry.
I have tried messing around with an android app. to do something similar - but ain't had much luck
getting it work right.

😀

Just recently viewed this video from MIT. Pretty amazing.

[flash width=560 height=315] http://www.youtube.com/v/jUeGnMH9coI?version=3&hl=en_US [/flash]

Automatic Building Mapping at MIT

JBS

Thanks JB. Great surveyors research both the law and new technology.

It's my impression that the reason inertial is little used in surveying is the drift rate of the measurements. They are stable enough to perhaps map a mine, with somewhat frequent return trips to the starting point to close the loop and recalibrate. But they won't hold survey precision all day.

IMU/GNSS positioning is a part of most if not all mobile land based or airborne based mapping systems. The ones we use show a drift rate of around 1/3 degree per hour, long level flight starts showing the drift. The key is the IMU is closely coupled with the GNSS, they augment each other. This may not work for ground pounding where you may not have any GNSS coverage for quite some time, BUT I think they are always working on this. Indoor positioning is big business and folks are working on perfecting this where you wouldn't have the GNSS.

SHG

Here's the one I used in the service

Shelby... I've been watching this one for awhile as well.... seems Locata is out front on this one so far (from what I've seen).

Could easily be another "wrench" in the survey toolbox..... if we don't let the other kids run off with it like we have in the past. 🙂

Great image of a 25 PIGA - gyro accelerometers are regarded by inertial guidance folks as the most accurate over other types. The PIGAs were miniaturized and I have seen pieces of, but not a complete, 16 PIGA (so, about 1.6 inch diameter case). I have heard there was even a 10 PIGA. The insides must look like a wristwatch innards.

I'm not a surveyor (sorry) but I've been interested in navigation, guidance, and surveying since I was a kid. My uncle, before he retired, was the Chief Engineer for the City of Los Angeles, so I have some surveying connection besides interest (and collecting).

I have seen the Litton PADS mentioned in this thread. I believe that Honeywell also made a system, though I have not seen it. The British firm of Ferranti also made an inertial surveying system. The high prices at least in part reflect the origin of these - they are basically modified from aircraft inertial navigation systems, so they were built (mostly) to Department of Defense specifications in the first place. The inertial platform used in the PADS was also one of Litton's most expensive - it used a pair of G300 two-axis gyros. These had beryllium cases and the wheel used gas bearings for long life and low drift. The cousin of this system flew in many US aircraft including the F-14 Tomcat.

There is a company whose name I do not recall but that makes a "borehole" inertial system. It is designed to go down a hole being drilled for oil or gas and returns its postion via the cable. It uses a "strapdown" configuration - the gyros and accelerometers are not free to gimbal around, so position information is gained by doing a lot of real-time computing.

I presume that much inertial surveying has gone the way of the transit and Gunter's chain becuase of GPS.

Thanks for the fascinating posts - great reading for an enthusiast.

Steven Hori

Will this lead to pink bean bag pin cushions all over rural AK?