Greetings.?ÿ I'm looking for a device to measure the vertical distance between a vehicle-mounted GPS/GNSS antenna and the ground, updated every second.?ÿ It's needed to compensate for the suspension, while driving to obtain a digital terrain model.?ÿ Would you recommend laser-based system??ÿ
I've only found high-end laser+inertial road profilometer systems, to obtain road roughness, texture, etc. but that seems expensive:
< https://romdas.com/modules/laser>
Thanks. FGN
Drive slower, add stiffer shocks, drag a trailer.
I struggled with this concept a couple of years ago, and spent many, many hours looking into it and bought various bits and pieces with the intention of setting something up that - using SurvCE on the DC - would "appear" as a depth sounder and hence would automatically adjust the Z. I bought a few of these things:
And Raspberry Pi stuff to control it, but never got around to working out how to set it up. I was also hexed by thoughts of tilt compensators and gimbals. But in the end just built a frame for the ute, shot the level of the receiver relative to the ground, closed one eye, and drove.
Having said that, I see there is now this:
Which I think I'll buy to add to my collection of stuff that I can't remember what it's for.
The US NOAA/NGS Airport Survey??s uses/used a towed unit shown in their logo. Copied below. Contact them for details.
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Back in the early 1990s I was working with a state agency that had acquired an ARAN (now owned by FUGRO). Impressive collection of sensors. At that time the agency planned to base their work on road mileage markers. They did add a L1-only GPS later.?ÿ
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More pictures of the profiler are here:?ÿ https://www.ngs.noaa.gov/AERO/navimages/cmanual_profiler.html
I am not sure of the accuracy specification but this device is used to capture airport runway heights. I believe only along the centerline.
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I built a contraption a few years ago for profiling pavement. ?ÿI've only used it with a robot and prism, but its just a trailer with about a 8' tongue, ball hitch, and an upright about 6' long with a 5/8" bolt welded on top that can be folded down to the front for transport. ?ÿIt's got about a 2' long axle between 2 of those small trailer tires. I pull it slowly behind my ranger. If you are using gps I would question how accurate your shots are going to be for pavement anyway. ?ÿ
Thanks everyone for the ideas.
The LIDAR-lite v3 seems the way to go.
It's made by Garmin, so it should be reliable:
https://buy.garmin.com/en-US/US/p/557294#specs
http://static.garmin.com/pumac/LIDAR_Lite_v3_Operation_Manual_and_Technical_Specifications.pdf
SparkFun put together a hookup guide, the bill of materials is $159:
https://learn.sparkfun.com/tutorials/lidar-lite-v3-hookup-guide
The following additional "shield" provides SD card logging capability plus a low-cost GPS, which should be precise enough for timing purposes:
https://www.sparkfun.com/products/13750
Here's the secondary hookup guide:
https://learn.sparkfun.com/tutorials/gps-logger-shield-hookup-guide
The final bill of materials, including batteries and memory card, totals?ÿ$246.89.
The only issue now is to combine the source code provided for handling the LIDAR with the one for GPS and SD logging.
I'm assuming the high-end GNSS antenna would sit on top of this contraption, i.e., there's only a constant vertical offset to deal with.
If only I had time to play with these... I'll leave it here for the future.
-FGN.