construction Laser level for digger

Using Arduino Project Guidance
#1

I have a digger and I will dig drainage at the farm. It has to have a slope of 3mm/m and every drainage is 100-500 meters long, I need laser guidence.

Something like this:

and

and

Problem is that they are expensive :0

I was planning to make a simple green laser pointer set up in one end and mount a white paper with a target on the diggers stick, but that's not gonna work in the sunlight.

Trenches is straight so I don't need 360 degrees, but like 10 degrees would help, that means that laser must move, thinking a pivot point at the front and the back swings, might be a servo. I think it must be harder to make it rotate and keep precision. But it still has to be very steady, if it could be not moving it would be better. I then set angle by hand using a m6 threaded screw.

I think laser must be modulated to not get interference by sunlight, but it also "rotates", how do I attack that problem?

Next is the receiver on the digger, what do I use to get the laser signal but not the sun?
A photo resistor will probably not work, or will it if I modulate signal? Is photo transistors or photo diodes better? (don't really know the difference)
If I use green laser I might cover receiver in green plastic to filter other light, will that be enough?

The receiver might be simple, just a couples of sensors in an line, if beam hits the one in the middle, a light turns green, it it hits one above I get a red light above, or more red lights if I am far to down. Same if I am high. OR I get a display in the cab that show me how far from zero I am 8)

My experiences level:
I have been playing with arduino a few weeks and have a bunch of cool sensors to play with, been doing some easy electronics for a few years, programming VB for a few years (some years ago). So I am kind of a beginner.

Will it be possible for me to make this work? :blush:

#2

Problem is that they are expensive

Laser levels don't seem all that expensive.

#3

zoomkat:

Problem is that they are expensive

Laser levels don't seem all that expensive.

http://www.harborfreight.com/catalogsearch/result?q=laser+level

Well I am sorry to say that if you want to use them more then 30 meters away (well I might use the cheap ones in 10 meters) and get some good result they are... If you then want to get a grade (is that the word ?) and I have to, they get even more expensive, and a receiver for a digger is a little more then a simple to.

Cheapest laser in Sweden that is good enough is 2000 dollars (14 000kr) and the receiver for digger is 2300 dollars (16 000kr), so we have about 4300 dollars (30 000kr) + VAT to get a system that works. Then they are much better then what I can build, but the cheaper ones is useless at a distance and cant tilt at all (well they do tilt and that is the problem, I need it to tilt in a controlled way :wink: )
And something like I plan to build is not in the market, probably because it will be a pain to set it up :cold_sweat:

This will work, much better price in UK but still a lot of money, that I don't have to spend...
http://www.laserlevelshop.co.uk/showdetails.asp?id=525
http://www.laserlevelshop.co.uk/showdetails.asp?id=164

#4

If being within your tolerances is really important, hire a professional to shoot and layout your grade for you. You may be able to find surveying equipment for rent at tool/equipment rental stores equipment rental is big in the US.

#5

Have you considered using a water level? The old fashioned ‘sticks and string’ approach would surely do everything you need, at almost zero cost.

#6

If you're using a laser + receiver then you want to blink the laser at 38Khz and use three-pin IR receiver module to detect that signal. It's the type of IR receiver that would be used in TV's, etc. with a remote control, but you want a specific subtype that will allow a continuous 38KHz signal. Vishay describes their modules as "fixed gain" in their product matrix. They are really quite simple to use; when the receiver sees the light signal it sets its output pin voltage low and when no signal is present it sets its output pin high.

So on your receiver you need to have a row of X many receivers (~9 or so) to cover the physical distance you want and a way to invert the signal to turn a LED on/off when the laser beam is shining on that corresponding receiver. I believe this is the type of method that is used by the type of laser receiver used in your picture.

On the laser end you need to blink that laser at 38Khz and this can be done with an Arduino or more cheaply with just a 555 timer. Any cheap pen laser will do that without any issue and give you multiple tens of meters of range. A red laser is preferred as that is closest to IR frequency. In your case you need a wide, flat beam and you can find laser pointer modules that will put out a line (I'm sure you've used non-spinning laser levels that cast lines on walls, etc.), but I can't comment on how the reception distance will change in that respect. If the laser line is visible to you then it will be plenty visible to the receiver.

#7

It appears to me that you are approaching this from wrong angle.
Instead of trying to dig out the precise trench, dig deeper and fill it up to suit your gradient. Use the above mentioned water level method (a transparent hose partially filled witht water). It will be significantly more accurate than trying to get milimeter accuracy with an excavator that tumbles around uneven surface.

#8

I wasn't suggesting using transparent hose.

A water level is just two containers connected by a hose. No matter how far apart they are, you know that the water level will be the same. With that as a reference you can set up a pole to give you a visible height reference to work against. It's all very low tech, simple and reliable.

#9

Chagrin:
If you're using a laser + receiver then you want to blink the laser at 38Khz and use three-pin IR receiver module to detect that signal. It's the type of IR receiver that would be used in TV's, etc. with a remote control, but you want a specific subtype that will allow a continuous 38KHz signal. Vishay describes their modules as "fixed gain" in their product matrix. They are really quite simple to use; when the receiver sees the light signal it sets its output pin voltage low and when no signal is present it sets its output pin high.

So on your receiver you need to have a row of X many receivers (~9 or so) to cover the physical distance you want and a way to invert the signal to turn a LED on/off when the laser beam is shining on that corresponding receiver. I believe this is the type of method that is used by the type of laser receiver used in your picture.

On the laser end you need to blink that laser at 38Khz and this can be done with an Arduino or more cheaply with just a 555 timer. Any cheap pen laser will do that without any issue and give you multiple tens of meters of range. A red laser is preferred as that is closest to IR frequency. In your case you need a wide, flat beam and you can find laser pointer modules that will put out a line (I'm sure you've used non-spinning laser levels that cast lines on walls, etc.), but I can't comment on how the reception distance will change in that respect. If the laser line is visible to you then it will be plenty visible to the receiver.

Thanks, I think you are on my track.
Would these be right? http://www.ebay.com/itm/IR-Receiver-Module-38-kHz-TSOP4838-FREE-SHIPPING-/260837712263?pt=LH_DefaultDomain_0&hash=item3cbb23a187

I might use a IR laser, but I only found one on 300mw, sounds kind of dangerous when I can't see the beam and hard to aim, but effective...
I got a few green lasers, they can be seen ok in daytime, and had a narrow beam. I can find red also, but is there some "ir" sensor that see green (well not ir any more, but I guess you know what I mean)?

I would want a bunch of receivers in a line, the ones to buy is about 250mm long. But if I only get 1 to work, the rest will work to.
If I get a laser that have a horizontal line, I don't have to have a moving part and that is good . Ordered one from ebay just now, I have a water level that have a line, but that is very faint, hope this will be stronger. A problem is that they are made for use indoors and are very wide angled, outdoors at distance beam get very very wide and weak. I would like beam to be 1 meter wide 50 meters away... That's why I plan to make laser move, professional lasers rotate and the beam is precisely 90 degrees, I cant find that precision in my budget. Just hope I don't loose to much precision by that...

You say that if I can see it, the receiver will see it easy, is that if I see it at night or daylight? I want 300 meters :astonished:

Some comments to rest of answers:
No I can't dig deeper and fill, it will pack and I need bottom to be +-15mm now and after 10 years or I get sediment trapped and a non working drainage. But I do plan to do the last 2-5cm by hand, but it will be narrow and deep for shovel.

A water level on string, or hose type is good for making something medium sized like a garage or so, there it would work just fine.
Here we talk of something like 3000 meters of digging out in the fields.

Tolerance is important and I have been working as a measuring engineer (is that the word?) for 7 years at building sites, but is now a project manager instead and don't have access to the old toys :frowning: To get some one to do it will not work as it will be needed all the time.
I could rent the equipment, but I will use it all spring, summer and autumn so it will be lots of money on rental.

#10

It depends how much you're willing to trade off time versus money. If time was irrelevant, it would be possible to use a water level out to whatever distance you want just by using intermediate reference points. But from your last post I get the impression you're looking for something much more convenient and quicker to use. Is conventional optical survey equipment out of the question? A laser scanner/detector is going to need a lot of work, and I suspect a laser that can be detected reliably over 3km is going to have enough power to be a hazard - I'm a bit concerned about the prospect of laser beams being sprayed around a building site where you could expect to find people without eye protection.

What sort of accuracy do you need? I seem to recall people reporting surprisingly high resolution from barometric height sensors and I wonder whether that's worth investigating.

#11

christerLun:
Would these be right? http://www.ebay.com/itm/IR-Receiver-Module-38-kHz-TSOP4838-FREE-SHIPPING-/260837712263?pt=LH_DefaultDomain_0&hash=item3cbb23a187

No. From the datasheet:

  • After each burst which is between 10 cycles and 70
    cycles a gap time of at least 14 cycles is necessary.

This is what you're trying to avoid. You want to be able to continuously blink your laser so you get a continuous signal from your receivers, but this receiver requires that you add "gap time" in the signal. All receivers designed for remote control use (PCM, Sony, RC-5, etc.) will have these "gap time" requirements.

Btw, 300 meter range is extremely ambitious. Keeping a tight beam over that distance would require some pretty serious optics.

#12

Thanks, I would never have known about that "trap" without help, feels like it has saved me lot of time searching for that error that made it work sometimes... ]:slight_smile:

Been reading almost all data sheets and as you say they want that pause. Might it work to make laser blink 60 bursts, wait 20 and so on?
Hmm, how much is a burst and a cycle?

It blinks at 38kHz all the time it is on, I guess that the remote (for TV or so) then want 600us pulses / bursts of 38kHz / 600us off and (max)70 of these makes a cycle?????
That gives me a blinking laser of 600us 50 or so times and that 600us is 38kHz?

http://www.vishay.com/docs/82484/tsmp1138.pdf found this universal, can't read out anything about needing a pause here.
How about sensitivity, and disturbance? The pause I understand (?) is to filter disturbance, will I get problem if 1138 don't have it?
Don't understand everything I must admit :blush:

300 meters is a lot yes, if I get 100 meters ( or even 50 m ) that is good, I can move laser a few times a day...

One problem is that laser must move, I am afraid it will wobble. I think that the pro ones have laser stationary and a prism rotating, but that will not be easier for me.

Added:
Red laser is about 680 nm (max 740nm), looking at chart ir sensor will start to work at 800nm with peak of 950nm, will that be ok anyway?

#13

I have not used the "learning" type of receivers, only the "fixed gain" type. But, from the datasheet, yes it does look like it doesn't require any pauses in the signal. And to answer your other question about those pauses, yes they are there to eliminate interference; fluorescent lights appear to be a big cause of this interference due to their innate flickering.

You can use a receiver that requires pauses but it just makes the programming -- both in making the laser blink and in detecting the beam -- a little trickier.

#14

Thanks, I have ordered a few and a line ir laser, and a red line laser so I dont have to make a moving parts. I found 5mw, feels better then 300mw, will try how far it works and maybe go up a little, since it is a line I thinking that a few meters away 50 mw might be as "safe" as 5mw but if I am close, big no no. So 5mw it is for now.

I'll probably get back for more advices after trying them out :wink:

#15

Still waiting for vishay sensors, but did a 38khz generator for the laser.
How close to 38 kHz must I get?
I now have 38.16kHz, to that I guess we can add some % error in multimeter... Close enough?

#16

IR receivers are pretty tolerant when it comes to the pulse frequency.

#17

Now I have tested a little more and I can say that the ir sensor don't see red. And the 38kHz signal must then be pulsed again, at max 60 pulses at the time.
Working on several solutions for now.

I have a ir-laser that I am working on and it seems to work with arduino indoor at least. But it is hard to work when you cant see the beam at all so if I can find something that can see red laser it would be better.
Is it possible to use photodiode or phottransistor if I use a redfilter? I guess it (laser) still need to be pulsed in some way to separate from sunlight.
How do I get arduino to ignore steady light and only see if it pulses 4-10Hz (rotating lasers is about here) ?

Tried to buy one of there cheap rotating laser level and it is as I guessed, useless more then indoor and maybe, just maybe on the front porch. The receiver worked less then 5 meters outside, and accuracy inside at 5-10 meters was 20mm.

I got my hand on a 10 years old broken "real" laser level receiver, it seems to work on red laser, not pulse modulated, but it must pulse as laser dot rotate, 500rpm or so, I remember that it can be used at both fast and slow rotation.
It has a red filter on case as you can see on right hand case in middle.

But what do they use as receiver?

(long, thin, shiny thing in top/middle) See image below:

The signal receiver is loose, soldering gone after fall, LCD on the back is broken but front one seems ok, so I might fix it, but I still need a big, 25cm (10inch) so I have to build one anyway...

Below you can see how we do it today, think 2000 meters and it will be 3mm/1m. Too little and water get trapped, to much and I get above ground too soon.

#18

What part number are you using for your IR receiver? I know Vishay TSSP4038 will see a red laser just fine at ~40’ (did not test longer distance because my house is too small). I know the Vishay docs say that this particular receiver shouldn’t see that red wavelength but for whatever reason it is capable of it.

The receiver you see in your broken receiver is referred to broadly as a “position sensing detector” (PSD). I don’t think they’re a commodity item you’ll be able to get your hands on. See: http://www.on-trak.com/1lseries.html and http://www.on-trak.com/theory.html

#19

Chagrin:
The receiver you see in your broken receiver is referred to broadly as a "position sensing detector" (PSD). I don't think they're a commodity item you'll be able to get your hands on. See: Single-Axis Position Sensing Detectors - 1L Series and Theory Of Operation For Position Sensing Detectors - ON-TRAK

That will work, but since we work at outdoor, we might need select matching pair (wavelength) of PSD with rotating laser.

Here is low cost laser level detector, we could use it as biased to modify;-

Laser Level Detector

select matching pair of photodiode with rotating laser;-

sonnyyu:
Plan C. matching pair of photodiode with no attenuate.

Sample:-

MTD5052N

digikey,$7.55

matching pair of photodiode will increase detect distance as well.

#20

Thanks, I use vishay 4838, it can see red but only at short distance, not even 2 meters.
I also have 1138, but cant get it to work at all. It is for relaying signal, So I guess that 38kHz pulses in will give the same 38Khz pulses out...
The ir reciever is easy to use so that is a good thing, cant find 4038 on ebay.

I have it to work (IR-laser) on one 4838 now, but it would be "easy" i hope to duplicate the code for more of them. If I could only see ir :wink:

No PSD on ebay... but I know what it is at least :slight_smile:

The circuit for receiver looks interesting, but complicated, for me at least. Maybe it clears if I start to build, all the IC1a,b,c,d is the same so it will hopefully look less complicated in real life.
But it might be possible to use that photodiode and a arduino.