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Property line and construction staking with a robotic
Posted by CapeCodder on December 7, 2019 at 1:21 pmMy company is considering a Geomax CR 3/5, my question is, when setting a hub and tack do you use that 360 prism? or will the standard prism poles work? I’m used to plumming down from a level tape. I’ll be doing this solo so there are some things I’ll need to know in advance. That 360 prism pole with attached data collector/remote doesn’t seem like something you’d be jamming into the ground to plum from. I’m guessing you keep moving it until you’re there then set the hub? And how is the accuracy setting the tack when you’re working solo? Thanks in advance.
jkinak replied 4 years, 4 months ago 15 Members · 22 Replies- 22 Replies
Yes you will use 360 prism. Just make sure rod is always calibrated to plum I check my rod up to twice a month. I use a pole with bipod. I stakeout to my point with bipod set hub. Impression the tip of rod in hub at the right point. Set tack then save stake. Using the 360 prism is very accurate and using a bipod when construction staking is a lot easier.
First, welcome to the site. Glad to have you.
Second, going from doing layout with a tape to doing with a robot is a big leap. Prepare to have your mind blown.
IMO, the 360 prism is a must have for robotic work. It goes on top of a standard prism pole. And with the data collector also on the pole, you are going to want a bipod to keep the whole thing upright when you are working solo. Some will tell you that the 360 isn’t as precise as the more common single prism, and that is technically true. But there are a lot of things in your error budget that have a much greater effect. Take care of those things and you will be able to afford the small degradation the 360 contributes.
I do a lot of high precision commercial building layout work with a robot, radially staking from resected intrument positions. I’ve had no problem meeting precision requirements. Do be certain to maintain your rod bubble and tribrach adjustments, etc. Level up with the bipod carefully when necessary. You can get into the +/-0.02′ area, or better, without heroic effort.
Finally, working robotic doesn’t have to always equal working solo. Layout goes much faster with 2 people and a robot. The roles are different, but there is still room for 2. Even when doing topo, there are still some things for a second person to be doing.
Embrace the technology. It’s good for us old codgers to limber up the mind with new ideas. Keeps us young.
The first comment is spot on. As with any use of a prism pole, rod bubble calibration and discipline is critical. You can also eliminate prism error by placing the center of any one side directly towards the instrument. Assuming you’ve handled the other issues, this can make it super nice. Your instruments calibration is always critical for high accuracy as well. You can easily get fantastic results if your fundamentals are solid. Never over look them. Find a tool to check your rod bubbles in the field. It will blow your mind how easily they go out and how much it can effect you. It is nothing to get 0.10′ error with a bad bubble. Also, take time to read your instruments instructions, they typically show you how to calibrate them and once you are well versed it is quite simple to do when you have good conditions to do so. Good luck and keep doing what you are, asking good questions and learning.
@norman-oklahoma
Thanks for the response, I don’t work primarily with tapes, only to plum from the prism pole to set a stake, then finish off setting the hub and tack with a hand prism and plumbob. The gear I’m using is all Carlson, Geomax 20, Surveyor 2 data collector and a BRX6 GPS. I just wanted to be certain that I’ll be able to set beanpoles and hubs running solo with a robotic.
Thanks, So single prisms mounted on telescopic rods can be used with robotics as well?
Howdy and welcome ??
Starting operations solo, your new best friend with a prism pole will be a two or three legged bipod. No need to plunge your superfine point into the ground with that connected to your pole. You can set that up very quickly to allow you to command the data collector and then pull out your trusty ole’ tape to a distance and get very close for your next shot.
I rarely use a bipod when working robotic, unless its a windy day. I use a brace stick instead, which is much quicker to plumb with than a bipod. With properly adjusted equipment it’s not hard to get below the 0.02′ value noted above. In moderate wind I’ll use 2 sticks (one of them a 4′ lath), and only if it’s really blowing (e.g. 30 mph range) will I break out a bipod.
As far as staking technique goes, if I’m setting rebars I’ll keep adjusting the pole in the dirt until I’m within 2 or 3 hundredths and then start driving the bar. When I get the top within a couple of tenths of the ground I’ll take a check shot and bump the rebar if needed. When I get it to depth I cap it, shoot the center of the cap, and make a punch mark based on the indicated move. Finally I take a check shot on the punch mark and store it.
If I’m setting marks in concrete I’ll get within a a few hundredths, then make a pencil mark at the indicated move and take a check shot. If it’s good I scribe a cross and drill in the mark, then punch it at the cross point, shoot the punch mark and store it.
For hubs and tacks (which I don’t set often, as I rarely do construction staking) it’s easy to get close enough for the hub, then shoot the center and make the indicated move to set the tack.
If I want accuracy, I have a point a short piece of thread all I screw on the bottom of the 360 prism that makes it only about a foot high. My Trimble prism has a level bubble built in the top of it so it works well.
A lot of good points here. In addition to the prism pole bubble, keeping your backsite tribrachs calibrated tight helps too. I use a 360 prism for most hub and tack layout. I’ve been doing some layout on top of a plywood deck lately that needed to be real tight. I used a seco mini stakeout prism attached to the bottom of my prism pole. Also I had an 8′ bubble in my prism pole. I haven’t seen anyone else doing that, but it seems to work out real well. All the tacs I set checked from a second setup under 0.01′
I add a second level vial at about 34″ above the ground, to all of my prism poles (both EDM and RTK poles). This helps with measuring taller monuments and lets me know when a vial calibration is needed.
- Posted by: @rpls#
Also I had an 8′ bubble in my prism pole.
After regular equipment checking/calibration, this is probably the single most important thing you can do to increase measurement accuracy in a production environment. The standard 40-minute bubble introduces way too much slop for anything but casual topo work.
I rarely use a 360 and stay with a circle prism – there is a bit of vertical error with some of them and it is not hard to keep it facing the gun for lock
I also have a leica mini on a small rod that has the same offset and I can get the shot at ground level 0.31 rod height and that keeps things tight for layout, as long as you can see a low rod – it has 4 sections, so I can move it up to about 4 feet if needed
Nice to be able to take shots while on the ground setting the point – up and down gets old fast
do check the bubble – I usually test the rod on the backsight or a check shot and turn it 90 deg to see if the reading match – a bi-pod is really handy and the carbon ones are light and pretty affordable these days – make a collar for the clamp so it does not crush the rod – split a pvc pipe – unless you use a heavier metal pole
Make sure to do some check shots during the day and before setting the first point – nothing worse that getting part way done and finding some error
Avoid resections when possible they lead to adding error into control – but if you must use 3-4 for the solution and then check two others
How I’ve steadied the pole:
-wide, firm, triangular stance with my legs
-elbows against your waist
-one hand on the pole, one hand on the DC
-*gently* rest your forehead on the rod when you’re level (may require some slight readjustment)
-if you have a stick of lath, hold it in your left hand (takes a bit of finger gymnastics, you can hold the pole and point the lathe out front to help stabilize)
Looks goofy, but it works in a pinch…….and I usually have to pinch as I often forget the bipod.
That works until you have to move one hand to operate the dc. I’ve used the laths. And I can also steady up pretty well without any external props at all. Still, I go with a bipod. This is what quality control is all about – adopting methods that increase the chances of getting a good product.
So…I can do it, but can the guy I hired last month also do it? Everytime? More importantly – will he (or she) do it? Using the bipod is my way of being sure (or, at least, increasing the chance) that good plumb is actually being achieved.
I agree with using at least 3 points when resecting. I disagree with resection “adding error into control”.
@norman-oklahoma
Yes. We actually teach our layout guys (carpenters) to use the same baseline of two points as much as possible and then check into some recently staked points.
That means you are extrapolating the same errors each time you set up. Which is fine, it gets you the consistency that is very important in such an application. And it is a simple directive that is easy to understand and enforce. But if you were to set up your instrument in roughly the same place and resect using the same control points each time, you would also get very good consistency. It’s not the resecting, or not resecting. It is the consistency in your process.
- Posted by: @rkinnie
Avoid resections when possible they lead to adding error into control – but if you must use 3-4 for the solution and then check two others
I don’t know where this ridiculous myth got started but I hear it all the time.
Resectioning eliminates error that would otherwise be present in a single-backsight setup – specifically, instrument measure-up and centering error. It does not “add error into control”.
A properly performed resection from good control will be better than a single-backsight setup from the same control, every time.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman - Posted by: @norman-oklahoma
That works until you have to move one hand to operate the dc. I’ve used the laths. And I can also steady up pretty well without any external props at all. Still, I go with a bipod. This is what quality control is all about – adopting methods that increase the chances of getting a good product.
So…I can do it, but can the guy I hired last month also do it? Everytime? More importantly – will he (or she) do it? Using the bipod is my way of being sure (or, at least, increasing the chance) that good plumb is actually being achieved.
I can appreciate that train of thought.
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