Hello, I'm new to these forums, but I thought I would ask a question. I have been working with a Trimble Robotic Total Station (5000 series) purchased in 2007. After performing a topographic survey of a concrete structure, I have noticed that when I compare the elevations observed with the Robot with elevations observed with an automatic level, I have quite a bit of variance. With the Robot, the closer my foresights are to my backsight, the more accurate my elevations are. The further away from the backsight I go, the worse the elevations become. In an approximate 600 foot length of foresights, I will have a variance of up to 0.12'.
This project requires precisions of less than 0.04'. The Robotic Total Station had recently been calibrated and adjusted by the manufacturer. I am wondering if the compensation routine is causing my vertical axis to get out of alignment. Has anyone had a similar experience?
I am sorry if this is not very clear. I may be overlooking something very simple. I am confident of my methodology. I checked into my previously established control points by less than 0.01' each time I performed a backsight check. Does anyone have a suggestion or advice? Thanks in advance for your consideration.
Replies
One question,
Are you running this in robotic mode?
Ralph
Yes. I was operating the robotic total station remotely via radio link. It would track my prism pole.
I think that's where the problem lies, set up and shoot the points manually with a conventional prism setup (not the 360) and check them versus your level via a remote elevation routine. I have a 5603 and I think that's where your problem lies.
Ralph
I have a Trimble S6 and have had no issue like this. Before owning the S6 I had two Geodimeter 400's one purchased in 1994 and the other in 1996. The Trimble 5000 is the Geodimeter 400 with some minor tweaks. One of my Geodimeters had a similar problem and it had to do with the Autolock. This probably needs to be adjusted. If you run the autolock adjustment routine and you still find you are not centered on the prism when you look through the scope then you will probably need to send it for a factory adjustment to take this error out of the instrument. I hope this helps and is clearer than mud.Ā
Well, I'm glad I'm not alone. Another surveyor I work closely with had suggested a very similar explanation. We will have to talk with our dealer soon. Thanks.
How's your optical plummet? Its hard to imagine it being off so far just from leveling your tribrach, but it definitely seems like you need further evaluation of its accuracy.Ā ON another note, I don't think I would EVER take shots or stakeout points with my backsight closer to me than my foresight.Ā This is most likely the reason for your errors.Ā Move your backsight a quarter mile away and try it then
Well, actually, I did not take any foresights that were further than by backsight. I also was checking into the backsight very tight. I have store shots and RAW data to back that up. Would you happen to know the kind of precision I should expect from this type of equipment? What does the compensation routine for the total station actually do? Thanks.
I would refer to your manual for the precision and the reason for the compensation routine, I am only familiar with Topcon robots, unfortunately. Is the error consistent every time you setup?Ā I wonder if you moved your robot to a new point and stored the same shots on the concrete structure, would you get the same results/errors? My second thought is maybe your automatic level has been dropped!Ā It seems like your robot have been in for service, and your control network is checking out ok, that would be my next step is a peg test with your level, maybe even bring it in to get checked out.