Trimble Turned Angle Issue

Somebody kick the True Plumb in the office? Are your tri-brachs getting calibrated? Do you use Measure Rounds in Trimble Access to run your traverse? Check prism constants? It's wild that it's happening across multiple crews.

What are they turning to and how are they locking onto the prism? Are they using autolock? If autolock is not calibrated correctly this will cause the problem.

Not all dealers/service centers are equal, and sometimes they screw up just like we do. Run check & adjust on every instrument, and see if any of the values change by a large amount. If so, there's your culprit.

Outside of that, I'm with @lurker , I would first guess that this is an autolock issue. Since it seems to keep popping up randomly, I would guess that either a specific instrument has an autolock issue, or one or more crews are turning it off / trying to force the crosshairs to match.

If everything seems OK there, I'd be looking at prisms and prism settings. Are they using a multi/active track prism? (If so, are they switching between active/semi/passive modes randomly?) Traverse kits? How about generic prisms? Are they nodal prisms? Or nodal prisms but flipped to use a 0mm offset thus making them non-nodal? That'll throw a wrench in both horizontal and vertical depending on circumstances.

We are checking it in access and TBC and we are seeing 9 seconds error per turn consistent. We visuall closed the horizon on bunch of different length points and the mean of those tests was under 2 seconds.

I am wondering about the Autolock feature though....Today I was checking the scope and it was lining up dead center on the glass every time. My group uses Leica's and forcing the robot to center gave us a bunch of issues until we let the robot just do it's thing.

Good rule of thumb is to use all autolock or all manual pointing in the same round - dont mix and match.

Are you working to an MT1000 prism in active mode? Damage to the prism diodes can cause the instrument to mispoint.

Also might be worth checking there isn't an offset sneaking in

You should get exactly the same numbers with manual pointing, passive and active autolock. Try a round of each - anything standout?

I assume you are doing both F1 and F2

"If an adjustment is ran, closure is exceptional ..."

Naturally. That is what an adjustment does. It forces closure to be perfect. Fully buggered data will close exceptionally after adjustment.

A few thoughts:

1. Collimation is something that can and should be done regularly - maybe once week , once a month, whatever - by the user, in 5 minutes. You do not need to "send a gun in" to have that done.

2. Tripods, tribrachs, and glass have at least as much and probably much more to do with precision than the gun itself. If these things are of poor quality, or are old and sloppy, so will be your data.

3. The fact that your measured angles are always larger than true does not mean that there is nothing wrong with the equipment. Quite the opposite. It means that you have a systematic error happening.

4. I'd like to know what the "splits" of your angle doubling are. Are you doubling? If not you might try it and see if it doesn't clear up your problem.

FWIW, my experience with Topcons is that they need to be collimated almost daily. Leicas and Trimbles can go a long time between collimations and continue to perform at their rated specification.

1. Collimation is something that can and should be done regularly – maybe once week , once a month, whatever – by the user, in 5 minutes. You do not need to “send a gun in” to have that done.-The group always sent there units in and about a month ago ran the field collimation routines.....I am thinking this may be the culprit. I noticed on videos that it can be done on the DC OR the robot. I was told they did it on the robot...Could this be a double collimation issue that the robot is making an adjustment and then the DC is making a second adjustment?

2. Tripods, tribrachs, and glass have at least as much and probably much more to do with precision than the gun itself. If these things are of poor quality, or are old and sloppy, so will be your data.-All this gear has been checked and in good shape...Plus the odds of all 4 units having the same issues using different gear kind of negates this one.

3. The fact that your measured angles are always larger than true does not mean that there is nothing wrong with the equipment. Quite the opposite. It means that you have a systematic error happening.-I agree completely.....Since I know so little about Trimble gear, is why I reached out to you guys. Originally I had been told that Trimble did not have collimation routines and now I know that it does. With you guys mentioning the autolock compensation I am really thinking that may be the issue.

4. I’d like to know what the “splits” of your angle doubling are. Are you doubling? If not you might try it and see if it doesn’t clear up your problem.-We are doubling and the splits are floating in the +/-1" deviation range.....

I spoke with the other group's head field guy and tomorrow may have them run a loop on manual mode to see how it works. Would the shop run a check on the autolock collimation when it was brought in? I am going to give them a call to confirm.

Thank you guys for the help....Greatly appreciated.

I noticed on videos that it can be done on the DC OR the robot. I was told they did it on the robot…Could this be a double collimation issue that the robot is making an adjustment and then the DC is making a second adjustment?

Not with Trimble robotic instruments - running the routine on the DC merely means the interface is on the collector rather than the instrument. All the corrections are sent to, and stored in, the instrument itself.

I spoke with the other group’s head field guy and tomorrow may have them run a loop on manual mode to see how it works. Would the shop run a check on the autolock collimation when it was brought in? I am going to give them a call to confirm.

The shop certainly should calibrate the autolock as part of their standard regular maintenance & service routine. It doesn't mean that every shop does. We had an instance in the past year where a brand-new service tech flummoxed up the calibration for one of our robots and sent it back. This is why running Check & Adjust - and going through every single item - should be SOP when receiving an instrument back from the shop. As Norman mentioned, it only takes about 5-10 minutes. Most of that time is setting up the target and the instrument.

The best way to check the autolock is to point the instrument at a clearly visible full-size single prism (no Multi/ActiveTrack, and make sure it's ~100m away) manually and note the angular measurements (can use Survey Basic to see them). Then switch to autolock and watch the HA/VA values. They should not change at all - even if the crosshairs move off the target slightly. If they do change, then autolock needs to be collimated.

One last thought as I sit here with a nasty cold contemplating whether I want to work today or not...when you or the crews run Check & Adjust, make absolutely sure that you're not skipping steps and/or doing them out of order. If you go straight to Autolock Collimation and run the routine today, then someone runs the HA/VA Collimation the next week without re-running the autolock collimation, it's likely that the autolock is now whacked out.

Would the shop run a check on the autolock collimation when it was brought in?.

The autolock collimation is individual to the prism being used. The shop couldn't run such a collimation , meaningfully, without your prism.

I have seen this before. TWO things stick out on top of what the others have said. Run the Calibration and collimation routine on the robot even the autolock and leveling check as it runs through. it is hard to believe with you having several different robots they are all about to go down at same time. But When this starting happening to me it was maybe another month and what happened was the reader decoder inside was getting dusty and eventually the robot went nuts and was not turning at all but the angles were spinning like it was. Once we got that cleaned it was back bang on and no other issues. This was about 6 year old robot at the time. So clean and calibrate. I cant remember the technical term of that glass thing on inside but thats same thing happened to use for sure. The MT1000 on another robot I found a diode indented so when traversing with it I had to mark it so I never faced the bad diode at the robot for anything tight other than topo..

Thanks again gentlemen....After more testing yesterday we found that manual turned readings were 8" further clockwise (we were expecting 8-10" to counter the traverse closure errors). So today they are going to run a loop in manual mode to confirm that it corrects the issue. They also tried redoing the collimation routines and the routine came back noting no adjustment.....So not sure what is going on but a work around has been achieved and I am going to go back to my Leica instruments.

After more testing yesterday we found that manual turned readings were 8″ further clockwise (we were expecting 8-10″ to counter the traverse closure errors).

Are you saying that with autolock turned on, the turned angles were 8-10" different than manual pointings? For all of the instruments? The odds of that happening are extremely, if not astronomically, low...

They also tried redoing the collimation routines and the routine came back noting no adjustment…

If manual pointings are ten seconds off from the autolock pointings, then the autolock collimation adjustment routine will absolutely come back with a correction value. However, there is a limit to how much can be corrected without having to go back into the shop. Did the crews maybe see a message stating that the correction values were too high and could not be adjusted?

Also, if they had autolock on during the HA/VA collimation, prior to performing the autolock collimation, you'll likely see no or minimal correction values.

I've seen some instruments do some oddball things here and there, but never multiple units at the same time...while it's possible that all of them are going south at the same time, it's incredibly unlikely that they would all be having the exact same issue.

We haven't tested all the instruments yet that are having this issue, but the first one did have different angles between manual and autolock by 8 seconds. As to the collimation routines, I am not sure how they are doing them but the response I got was "we are doing them like the video's show". I will ask if they are using autolock going through the routines, but I would really hope they are smarter than that.

I honestly think they all started using the field collimation routines at the same time and that is causing it to appear like the same error is popping up across instruments and crews. The outlier being one unit went back to the dealer for adjustment and I would think it would have been addressed. I also recommended to them that they get their units cleaned as well as collimated in case it is something like that.