Activity Feed › Discussion Forums › Strictly Surveying › is Trimble R12 a better upgrade?
I don’t have an R12 (only a couple of R10-2’s without tilt), but my understanding is that you first need to be in motion, then it uses the change in position to orient the IMU (i.e. it computes the direction you are moving, compares it to the IMU, and applies the difference). Any IMU will drift over time, so it is constantly using the GNSS positions to update/correct the IMU.
@nate-the-surveyor I have read how IMU works and i Can not trust them 100%.
My other thought is how a low-cost receiver like CHC can be compared with trimble r12i as in my test gives accuracies of 2-3 cm difference in tilt mode and works pretty good under canopy.
Also, I think that Chinese has a low confidence level inside of their motherboard chipset in order to give ” fixed” results.
Does the IMU work well in extreme canopy? Or, does it degrade the tilt direction in canopy?
If it has a gyro inside, then I can see it working. If not, it may degrade.
Curious Nate
- Posted by: @johnymal
I have read how IMU works and i Can not trust them 100%.
I would hope that you’re not trusting your GNSS results 100% either…
We currently have about ~20 R12i receivers in the field. We have found that RTK+IMU solutions are generally repeatable to ~3-4cm under typical conditions. The IMU adds about ~5mm of positional error (RMS) plus less than 1cm if tilt is below 30 degrees. That’s about 15mm on top of the ~2cm that is common for RTK, so it generally lines up with the specs.
I wouldn’t go with a particular manufacturer based on a single feature, or the fact that a single item does slightly better than a competitor in one area. Other things are at least as (I would say far more) important for productivity, such as how intuitive the field software is, mechanisms to push data to/from the office, and ease of post-processing. It’s better to evaluate the whole package.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman - Posted by: @nate-the-surveyor
Does the IMU work well in extreme canopy? Or, does it degrade the tilt direction in canopy?
You need a good GNSS position solution to combine with the IMU heading. Under heavy canopy it’s more likely the the operator will be leaving the receiver stationary to allow the GNSS solution to converge. When that is the case, as @john-hamilton mentioned, there will probably not be enough motion to compute an IMU heading and combined solution.
It’s possible to thread that needle, but in practice it is increasingly difficult as the canopy gets thicker.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman It is hard to speak to the specifics of i90 comparative performance without knowing what options and OEM board is installed in it.
The i90 is available with a Trimble BD990 engine or a UniCoreCom OEM board (and perhaps others.) While not as varied in component possibility as the i70, I believe that there are a variety of modems, uhf, bluetooth available.
If the unit has a Trimble BD990 OEM board, there are a series of tracking options (you want them all), and you want the MaxPro option with OEM firmware 6.06. (There are slightly newer versions, but I would personally hold back for a while — it is currently Nov 2021 when I write this.)
If the unit has the UniCoreCom OEM engine, then there are other considerations.
I used to be able to guess what the options were by price and full part number, but I can’t do that anymore. I have to connect to a head with a serial cable, put in passthrough mode and then use PPP to connect to the internal engine and poke around. WinFlash reports 5.46 for devices with 6.06, and the web interface matches winflash.
There is also a possibility of changing performance by changing tracking options. Probably best to check everything and let the engine work it out on it’s own.
Finally the correction source is important. For the i90 to work best, it needs a fully enabled RTCM3.2 stream or sCMRx. sCMRx is scrambled CMRx and it is not compatible with CMRx by design. If you were going to do a head to head comparison, best to use either a R12 or i90 base broadcasting RTCM3.2 with everything enabled and tracking to 5 deg.
@mark-silver Why the huge price difference in prices between Trimble r12i that cost 20.000 $ approximately and the other i90 that costs 5000$ ? Can you explain this?
Maybe is a marketing game?
I have a feeling that the Chinese maybe give false float solutions sometimes (maybe they say fixed in DC and it will be not) in the other hand Trimble says that the accuracy of that data collector says is real.
I don’t think the $5200 price in the USA for a Trimble based board is possible because of tariffs. A BD990 based i90 without IMU Tilt is $7650 with IMU Tilt $10,300 (from a reputable US dealer with support and service.)
I think that $5200 might be possible without inbound shipping and without tariffs on a non-Trimble engine device without IMU. That is a lot of withouts, I know.
Trimble receivers command a higher price because of an extensive support network with local dealers. The R12’s are part of an extensive suite of integrated solutions: Scanners, Mobile, UAV, Robots, monitoring, infrastructure, scanning, remote sensing, levels, guidance, water management, resource utilization. Trimble has extensive software products also.
These differences in price exist in all products. Wrist watches, vehicles, homes, backhoes, welders, trailers, RV’s, drones… Sometimes they make sense, sometimes they don’t. A lot of the difference can be in marketing costs alone.
Thanks for the answers, but none answer me if Chinese receivers are worth the effort.
Maybe they have changed their confidence level from 99.9% to 90%? That’s why they give easily fixed soloutions?
- Posted by: @rover83Posted by: @johnymal
I have read how IMU works and i Can not trust them 100%.
I would hope that you’re not trusting your GNSS results 100% either…
We currently have about ~20 R12i receivers in the field. We have found that RTK+IMU solutions are generally repeatable to ~3-4cm under typical conditions. The IMU adds about ~5mm of positional error (RMS) plus less than 1cm if tilt is below 30 degrees. That’s about 15mm on top of the ~2cm that is common for RTK, so it generally lines up with the specs.
I wouldn’t go with a particular manufacturer based on a single feature, or the fact that a single item does slightly better than a competitor in one area. Other things are at least as (I would say far more) important for productivity, such as how intuitive the field software is, mechanisms to push data to/from the office, and ease of post-processing. It’s better to evaluate the whole package.
From your experience if an IMU ads some cm error is better to work with IMU closed when not need it?
- Posted by: @mark-silver
I used to be able to guess what the options were by price and full part number, but I can’t do that anymore. I have to connect to a head with a serial cable, put in passthrough mode and then use PPP to connect to the internal engine and poke around. WinFlash reports 5.46 for devices with 6.06, and the web interface matches winflash.
Dear, please, please, tell me more, how exactly? They gave me a MaxPro code, but I don’t know how to connect WinFlash to the board for my G1+ with BD990 … Or i can to see WEB of BD990 ??? Thank you !
I shot points very nervously under heavy canopy, as we were staking line my checks on line points were visual. However, I wanted the end points (monuments) to have better checks. The second worst location was a 1/4 on the west end of a E-W center section line. I had originally located it 6 months prior, located it a second time that same day within .02x.04′. Then six months later located it again with the same accuracy from a different base point. Other monuments along the property line were also located with similar results, some had been visited in the original search from 6 months before. Only one required extra surveying, it was against a large yellow pine and had to be set from offsets.
I’ve done many surveys in canopy with my R8-2’s and have good luck with them. I agree, the displayed error on the DC screen is not something to be treated as gospel. But second locations lately have been changing my mind somewhat. They seem to concur more with the screen than before.
I’m not about to state that bad fixes are a thing of the past, but error-trapping is causing them to be very rare.
Presume you are checking against previous surveys or conventional surveying which is known to be tight as two GNSS shots in canopy/ multipath/challenging conditions I find can still be giving you the same result twice but against tight traverse work is not right. I.e expect two 30 epoch rtk GNSS shots in open to be within 10mm at 95% CI but in cover/next to tree/utility pole you can get the same repeatiblity but the result is biased by the obstruction ~20mm. Have observed this with different brands of gear (including the magic Javad box & no I don’t think it was better than a top end Trimble/Lecia in canopy when checked against total station traversing known to be reliable) and making sure to use different satellite geometry. I’m in the southern hemisphere but still using the same satellites. Canopy here is usually pretty dense, as in no sunlight filters through, not gaps between trees.
If you have verified and still getting those results I take my hat off else suggest some conventional checks to be sure.
I’m using a 12i at the moment. I think the IMU is great, but that canopy busting stuff they talk about seems extremely hit or miss (mostly miss). I spent all week working in leave-less trees and I couldn’t get very good accuracy anywhere, even in the lightly wooded areas.
Possible to define the accuracy you were after but couldn’t get, and if it was just CQ’s or some higher confidence interval? Also distance from base receiver or NRTK?
Think it’s super helpful in these discussions to have actual numbers else some who work to 10-20mm think GNSS no good in canopy whereas others only after 30-50mm think its fine (and some others claim their flavour still gives the lower figures in any canopy).
Yeah, I really should have more specific data than “sometimes it sux and sometime it’s gud!”. ????
Anyway, I think for the project I’ve been working on lately we have a .06 residual tolerance set in the equipment with 2 sigma confidence, and this is what I seem to have trouble hitting in the field. These are just run of the mill topo shots in varies degrees of canopy so it’s unlikely any particular area will be revisited unless something looks completely whacky in the office. Also, we’re using a base and rover setup with an external radio even though we’re working less than a mile from the base.
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