Let's discuss IMU's

They used to be a back-pack.

http://www.trimble.com/gnss-inertial/AP15.aspx?dtID=overview&

I assume it's what's in PIGs. Recently I was shown a PIG plot compared to the GPS locations and it was amazing how accurate it was. And it went for 60 miles or so, how it's set-up I don't know, they must be somehow reset at the launcher. I do know they aren't cheap.

Smart pigs use a AGM which is a monument set at ground level on top off the pipe. You can put a box that has a clock built in on top of the monument. When the pig goes by it triggers a spike in the computer inside the pig. They use the multiple clocks set at maybe 5 mile intervals to control the speed . The AGM'S must help tie the pigs route to the pipeline route.

I also know someone that was in the military that used something similar and he said it rode in a Hummer it was so large. I assume its some kind of gyro system but don't know.

I've used both the Applanix POS, and the ZUPT back packs. Great for staking rough line in heavy canopy if you can live with 10-15' horizontal error in a mile. Post processed lines come in about 1/3 of that. These are used extensively in the twitterbugging world.

Tim Reed, post: 450154, member: 420 wrote: in the twitterbugging world.

What is this?

Twitterbugs / AKA Geophysical Seismic Exploration guys.

Tim Reed, post: 450163, member: 420 wrote: Twitterbugs / AKA Geophysical Seismic Exploration guys.

Times have changed. We use to call them doodlebugs.

http://leica-geosystems.com/products/gnss-systems/smart-antennas/leica-gs18-t

I know I heard of IMU surveying by helicopter teams in Alaska., but that was a long time ago.... why would you want to use old technology to get bad data??

Andy J, post: 450596, member: 44 wrote: I know I heard of IMU surveying by helicopter teams in Alaska., but that was a long time ago.... why would you want to use old technology to get bad data??

IMU isn't the sole measurement source in this instance, it seems it is constantly providing data along with the GNSS to store a measurement. I have seen quite a few pictures floating around of angled pole measurements on known control with accuracy in the 0.02'-0.06' range. Pretty impressive technology released by Leica.

[USER=444]@Jules J.[/USER]

When I was a kid we used to call "Ant Lions" doodle bugs and spent hours throwing ants in their traps.

They didn't have video games back then just black and white TV, (with THREE channels) so we amused ourselves by playing outside from dawn to dusk climbing trees, playing baseball, riding bikes, fishing, and all of those now unheard of activities. 😉

We called them "mudbuggers".

Tagging for later.

Andy J, post: 450596, member: 44 wrote: I know I heard of IMU surveying by helicopter teams in Alaska., but that was a long time ago.... why would you want to use old technology to get bad data??

Andy, in the aerial mapping business we fly with integrated GNSS/IMU's on each sensor (camera, LiDAR, etc.). About 1/2 my work these days is post processing the trajectory, greatly enhances the downstream mapping processes and reduces ground control by at least a factor of two.

The IMU and GNSS complement each other, the IMU is typically recording data at 200 Hz and the GNSS at 2 hz, the two data sets align to each other and we typically achieve very good results, in fact this trajectory alone on our LiDAR flights processing with PPP (no ground control at all) produces agreement with check shots at the 0.1 foot level, obviously NOT the same as 20 year old technology. Of course we usually add ground control and adjust to it.

SHG

Shelby H. Griggs PLS, post: 451709, member: 335 wrote: Andy, in the aerial mapping business we fly with integrated GNSS/IMU's on each sensor (camera, LiDAR, etc.). About 1/2 my work these days is post processing the trajectory, greatly enhances the downstream mapping processes and reduces ground control by at least a factor of two.

The IMU and GNSS complement each other, the IMU is typically recording data at 200 Hz and the GNSS at 2 hz, the two data sets align to each other and we typically achieve very good results, in fact this trajectory alone on our LiDAR flights processing with PPP (no ground control at all) produces agreement with check shots at the 0.1 foot level, obviously NOT the same as 20 year old technology. Of course we usually add ground control and adjust to it.

SHG

Thanks, I had no idea that technology was even in use. Seems a long way from the stories I heard of gangs of helicopters tossing bags with powder out for targets to hover over!