Auto pointing at night with a robot

I have a Topcon GPT8005A, and have used it quite a bit at night, and I have not seen any issues. I would think that a prism would be better at night than a reflective sheet, but I have never used one, so I could be wrong.

I've had troubles with a Trimble S6 when I'm in a super bright area but beyond that light didn't seem to play an issue; that was using a prism with radio though.

Jimmy and curly,

Both of your responses would seem to confirm my suspicions. Generally speaking, that the beam used for auto pointing is generated by the instrument, and that as a result, it's function would nor be affected by surrounding light conditions. I further suspect that the difficulty in pointing I was experiencing last night had rather to do with the reflectivity of my sheet target. I'm going to experiment some more with other sheet targets to get a sense of the limits of their use. Thanks for your responses.

Al,

We have been using Leica robotics since the 90's. The target tracking work great at night, I actually prefer to work in the dark on some sites. The situations that were we have trouble usually involve looking into a setting sun but even that seems to only occur for short time on any given job site. The Leica system is totally passive.

John,

You've got me thinking now that maybe the SRX is passive as well, which I assume to mean that the instrument does not generate a signal in order to point. Then, is the method by which the robot points based on the image in the field of view, and some sort of software based analysis of brightness within that image? If no signal is generated by the instrument, why wouldn't the brightness of the target be affected by the surrounding light conditions, and therefore in turn affecting the auto pointing?

I did speak with a rep at Berntsen about auto pointing to sheet targets, and he said the Leica instruments work the best in that respect.

I've been looking at the Sokkia Srx. What is your opinion on that robotic total station?

I'm happy with the SRX. I think it provides excellent service and value. You should know however that I have very limited experience with other robots, so take my satisfaction with a grain of salt. Because of my prior experience with TDS, I made a choice against the grain and went with a TDS Nomad instead of the Carlson data collector that Sokkia typically pairs with the SRX. Even that decision has not turned out so bad. Survey Pro is a capable software collection package and service is good from (now) Spectra Precision. It works well with the SRX.

I think I might have opted for an imaging total station instead of the plain robot, if I had considered it a little further. That might be handled with the data collector in a somewhat satisfactory way, but built in to the total station would be even better.

Let me know if you have specific questions.

Al,

My understanding of Leica ATR uses a combination of infrared beam and imaging system to track the prism. That is why the system works well in most light conditions.

It will also pick up on the reflective tape with the little hexes. The question is which point on the material it locked on to.

I do have a few specific questions.
1) how much? I have checked Ebay and they had a SRX for about 12k, Is that close to what you paid? I have looked, not too seriously, at the trimble, leica and topcon. All are very expensive, and almost too involved in terms of software and complexity for turning angles, stake out and the basics. Leica is extremely nice, but extremely expensive. I think it was running about 55k with everything needed. Trimble is about 45k, and Topcon was about 25k, which is a lot better, but Sokkia is a reputable company with good equipment. I would just like to know what it actually cost somebody.
2) Have there been any radio linkage problems with your DC? Trimble is great when it works, but you change any of the hardware, and KABOOOOM your down a good while ready to throw that thing in the river.
3) How effective is it at finding the rod? just curious.

SRX is superb at tracking and target acquisition. I have used both the SRX and Geodimeter/Trimble and I prefer the SRX. Once you go into the search mode an active fan laser beacon (fan shaped in the vertical plane) on the rod is lit, and the instrument begins rotating looking for that beam. When it hits it it simply pans up and/or down to lock the glass. One caveat is that the fan beacon is offset about 2 tenths to the side of the glass so there are certain circumstances where although the glass has a line of sight to the gun, the fan beacon may not, simply a matter of moving to the side to get lock and then returning to the point for location.

As far as radio link problems I never had any with the Sokkia. Once it was set up it always worked. Also I never had any issue with conflicts with other survey crews like I have had with Geo/Trim.

RRain

Thank you for your response. It's good to hear things working as they are designed, especially when it comes to surveying equipment. Again, thank you.

Sorry for my delay in response.

1) I bought my SRX3 new and I think I paid about $23,000. $12,000 sounds like a pretty good deal for this instrument, considering its capabilities.

2) At first, I had difficulty with radio communication between the instrument and the data collector. The most serious problem had to do with the Instrument Settings in Survey Pro not "taking" the way they should. That software allows for pairing the data collector either directly to the SRX or indirectly to the SRX through the RCPR3 unit. I now go into the Instrument Settings screen multiple times before beginning to work on a job, to make sure that the settings are correct. These settings are usually made at the beginning of a field task, and it is at this point in time when radio communication is most likely to be idle. If it is idle when the changes to the instrument settings are made, then the changes don't take effect. At least, that's what I think is going on...After overcoming this problem, I have not had any serious problems with radio connectivity. There are times when the radio communication will go idle in the field, and it takes a minute or two for the connection to be re-established, which I do find somewhat frustrating, but it is not a major problem.

3) It seems very capable at finding the rod. However, I think most robots will have difficulty finding the prism at either long distances or with brush between the prism and the total station, or some combination of those two. Randy's comment about the fan beacon being offset from the prism is absolutely correct. If you are fortunate enough to be able to see the TS from the prism, you can avoid this problem, by tilting the prism pole just slightly to the left until the total station "finds" detects the fan beam and stops its horizontal rotation. Then, before the TS begins its search up and down for the prism, re-plumb the prism pole and the TS should find the prism.

One thing I am not especially fond of about the SRX is the size and weight of the RCPR3 unit, although this is a minor complaint. Also, I believe that Sokkia introduced a newer RCPR4 unit which is much lighter and smaller than the RCPR3. I had the opportunity to work with a Leica robot recently, and by contrast, there is no similar remote controller on the prism pole when using that system. The owner of that system, though, complained about the Leica being unable in some circumstances to find the prism, so the Sokkia system may be better in that respect. Six of one, half dozen the other....

I checked the Sokkia SRX manual, and confirmed that both auto tracking and auto pointing are performed using a pulse laser transmitter and CCD detector with co-axial optics. The signal source (emitted beam) is a infrared laser diode (830nm).

I cut out some triangles of "reflexite" type tape and experimented using them last night. The particular type of tape that I used has a grid of eqilateral triangles on it. The results were quite impressive. The pointing was accurate and fast.

I am disappointed however, that Survey Pro does not support the use of reflective sheet targets. I have a question in to support at Spectra Precision asking them to add this feature.