Cheap Laser Rangefinder / Distance Measurer Sensor
Ben Ward1e
Posts: 6
Hi,
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I was wondering if anybody can point me in the right direction for any schematics or guides building (or even buying) a relatively low cost laser based distance measurer.·I have found various devices on the market but they all seem to be priced around the·> $300 mark but at the same time they can measure distances much greater with much greater accuracy than what I would ever need as a hobbyist. I would like a device that could fairly accurately measure distances up to about 5 meters with an accuracy of +/- 5cm. I'm aware of ultrasound based sensors already but their accuracy isn't great and I think a laser based device would be much more accurate for mapping a room or area.
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Any suggestions or alternatives are welcome.
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Thanks
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Ben
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I was wondering if anybody can point me in the right direction for any schematics or guides building (or even buying) a relatively low cost laser based distance measurer.·I have found various devices on the market but they all seem to be priced around the·> $300 mark but at the same time they can measure distances much greater with much greater accuracy than what I would ever need as a hobbyist. I would like a device that could fairly accurately measure distances up to about 5 meters with an accuracy of +/- 5cm. I'm aware of ultrasound based sensors already but their accuracy isn't great and I think a laser based device would be much more accurate for mapping a room or area.
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Any suggestions or alternatives are welcome.
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Thanks
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Ben
Comments
If all you want is 5 meters check out the SRF10. It is a sonar unit with a range of 6 meters and starts at around 6 cm for about 70 bucks and·the accuracy is pretty exact.
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If you know of any existing guides or papers on how to make a relatively cheap laser based rangefinder myself that could also come in useful but i’ve not had much success with this so far.
Cheers
Ben
Be forewarned - its not cheap.
You may want to check out Mouser and Jameco - they both handle lasers and you might find what you want.
place the diode a fixed distance above the camera, pointed into the "view". As soon as the point moves "up" in the screen, you know the distacnce away from the camera.
see· :· http://sky.fit.qut.edu.au/~taylort2/Confirmation_Revised2.pdf
·for geometry ....
Caution, the following is just speculation. But, if you try it, please let the use know of its success or failure.
I also just had the idea of cutting out the covering over the LED part of a Sharp distance sensor. Then cut away the LED, and connect its source to a transistor to drive a Diode Laser. My understanding is that the distance range of the device is more an issue of where the lense of the detector is aimed and focused. By using the Laser, you can aim the beam anywhere in relation to the sensor you want. Perhaps you can mount the laser in putty as you aim it so that the sensor detects it at the right distance. By putting the laser further to the side, you also increase the amount of parallax, thus giving you more accuracy at distance. The tradeoff will be that the sharp sensor will work at a narrower, though further range.
Joe Dunfee
Laser diodes are easier talked about then pursued. The problem with mounting a laser diode on a CMU is distance and color. Identifying a color isn't a problem, identifiying a specific shade of color is a problem. CMU loses distance abilities before much happens, if there were a way to run the CMU software with a normal camera then distance would resolve itself quickly.
For the idea of using a laser to go up or down in a picture, your going to need very exact locations (probably to the pixel) on the camera picture. The farther out the laser is targeted the more exact the measurments will need to be.
So in short, don't think it can't be done, but do be aware of some of the problems you encounter. Personally I like using to cameras and by measuring which picture (or in this case laser spot) is bigger you can get an idea not only of how far away the object is, but also which side it will be on.
Alman, I just so happen to me a computer chip designer.. and guess what? im working on this vary thing. ladar imaging systems are in the near future and they will change the way robots can see the world. still a few years away from being something that will be on the market.. right now its just R&D for the government.. like NASA, the Airforce and others.. but we get to keep the tech when we are done with the R&D. and our plan is to market this to many different areas and one of them is robotics. this will change eveything about what they see. real 3d vision. so its in the new future
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Muahdib
IC layout designer
Phoenix Arizona
But, I've seen Ladar (time of flight based laser) systems for many years now. Of course, they've been extremely expensive, so not viable for the hobbiest. I've looked into them for input into CAD design systems, but all those point readings into something usable is the problem. It is a software challenge, not really hardware.
Regarding the Leica Distance meters, they are certainly affordable. But, I wonder how fast one can take readings from these devices. The ones that have bluetooth connectivity take such long time for a reading they aren't really viable for scanning. But, I don't know if that is because of the limitations of the technology, or just delays to prevent the user from accidentally taking readings they don't really want.
Do you think the hobbiest can hack into something like the Leica Distance meters, and then just use a mirror to scan the laser around?
Joe Dunfee
I think you missed my point.
My point wasn't about 3D vision or using cameras or using laser to navigate or create an image. My point was that software capable of identifying a moving laser dot in a picture doesn't exist. That aside the software to identify any color·spot in a picture is very limited.
3D laser imaging is whats going on with the DARPA Grand Challenge and those people are making leaps and bounds in the direction of image processing - 2D and 3D - to date none of them·has a way to identify a direction via a changing·photo. The requirements for this year mean identifying street signs, road markings and a few other things. To take a video feed and identify a shape and color is difficult at best, but to indicate motion is something very different. If there were software that could do that I would have jumped on it for my team. Right now even identifying the basic street sign shapes is an issue, not to mention the colors of the road markings.
People can and have overlaid laser scans on video images, Team Red did that last year, and·the winner Stanley did that also. But no one has been able to identify specifics in a picture well enough to track something from a picture.
Trust me, if only using video cameras·were able to indicate movement·my studio cameras would all have it and my team would be using it. I would jump on it without hesitation.
Something like that for motion picture, TV·or video would save retakes to a point of paying for itself quickly. (Remember that when a retake occurs the cost isn't just for a camera man but the whole crew.)
Our digital editing equipment still won't identify and correct problems on·its own, we have to go in and fix the problems on the first image before the computer will correct the rest of the images that follow. If I could get equipment to identify flaws on a photo my editing costs would drop.
So·my point is not if lasers can create images or be overlaid on a photo to create 2D or 3D, but rather trying identify from a picture whats on a picutre.
Post Edited (AIman) : 11/10/2006 6:45:17 PM GMT
As to your original question, in the "Bailing Wire and Rubberbands" column in the November and September 2006 issue of Servo magazine, there is a discussion of building your own inexpensive laser rangefinder. The article includes parts sources and the author has source code available from Servo's website for controlling the laser ($20 laser pointer)·and interfacing with a Taos TSL3301 linear image sensor ($10 from Mouser). Very interesting. I will probably build it. If I do, I'll share my experiences. http://www.servomagazine.com/.
Pierson
Post Edited (Pierson) : 11/14/2006 5:42:14 PM GMT
I have looked however and I can't find the article anywhere on the web. Is there an online version of the article anywhere that I can have a look at as I don't have a subscription to the magazine and it would most likely cost a small fortune to have the two issues·delivered to the UK. How much detail·does the article go into and what equipment is needed in order to calibrate the·sensor and get it working?
Ben
Okay, here are copies of two articles. www.servomagazine.com, free media downloads, under September and August 2006, has the code. Need to scavenge some Borland .dlls to make one of the programs to work.
Good luck, and let me know if you have any luck. I ordered some parts today.
Servo is available for online viewing with a one year subscription for about $19. That allows you to to view the magazine in a unique reader kinda similar to Adobe Reader. It allows you to go through the archives to view old magazines, and it also allows you to download entire magazines in .pdf and other formats. Servo also sells back·catalogs on CD. Parallax runs an ad on the back page of every issue.
Post Edited (Pierson) : 11/15/2006 11:22:49 AM GMT
A long wait. But it will give me some time to get together the rest of the parts. I bought 3 laser diodes off eBay for $6 a while ago. I have a very simple circuit in a book on my bookshelf to power them up, mounted on a block of wood and using a couple of batteries. It uses some lenses to produce a long-range beam, which you can modify for your purposes. The pages are in two Word attachments.
By the way, should we be posting copyrighted articles? I didn't see any reference to permission from the authors. Would these things be covered under "fair use"? If not, then perhaps you can just post a link to the web site showing the article. Of course, a magazine may allow the public access (like PC Magazine), or not (like Servo).
Joe Dunfee
The point of the last posting is only to show a method I had seen for operating a laser diode as a pointer, the very most basic of hardware and electrical connections needed to get a laser diode operating. It was only meant to supplement the concept of powering a laser diode.
As to the articles: If the copyright holder/owner/anyone objects to my placing them on the forum, I will delete them immediately. I believe, truthfully, that I have a fair use of those articles that includes distributing·single copies, via·a download, to individuals.·The articles aren't·published on the forum per say, I just·made a single copy available to individuals to download·to read.·I'm not a lawyer, and I·could be completely wrong, but that is what I believe to be correct.
It isn't to hard to find lasers to point, but finding the rcving half to make a range finder has left me stumped for almost 2 months. There are a couple of longer posts - in the Sandbox I think - that talk about this, but so far I haven't been able to locate anything that will work for the return signal.
For the other links there were many articles pointed out but either the links dealt with IR or the parts weren't available (and that means contacting the wholesalers and production company).
So if any one knows were to get the rcving parts please do post!
That is the link from Servo Magazine mentioned before. The article shows up in a small window on the right side about half way down the page.
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I understand your point.
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I was not really trying to comment on what software can or can't do at the moment. You are an expert, and there is no way I would try to tangle with you in your field[noparse]:)[/noparse]
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I think im saying is in the same vain as far as technology.. Or vision systems. What im working on right now is a way to have ladar systems that are cheap enough that they will be everywhere in the near future. The software that would use this information is not in my field of expertise but, if you have a ladar that can scan its field of vision every 100 micro seconds and dump 3d images into software that can pick out objects it understands.. You have what im working right now.
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What darppa is doing is cool.. But this will be better and cheaper.. A lot cheaper as it·is more of an IC / scanning laser solution.
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Sorry about not staying on your topic exactly..
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Muahdib
IC layout designer
Phoenix Arizona
I think the biggest challenge in the articles mentioned will be interfacing the TAOS TSL3301 with the BASIC Stamp that I was planning on using. I have read what it says in the servomagazine article and the interface is basically consists of 3 pins. 2 pins are for input and output of data to the sensor using a mish mash of RS232 and SPI, and a 3rd pin so you can provide the clock signal to the sensor. The sensor has a maximum speed of 10Mhz. Although there are good instructions in the article for connecting to the chip with PIC16F873 processor it would be very useful if anybody in this forum has tried interfacing a BASIC Stamp with a TAOS TSL3301 or a chip with a similar interface in order to benefit from their experience and/or any peculiarities they encountered along the way while making the interface.
Post Edited (Ben Ward1e) : 11/16/2006 10:12:17 PM GMT
If you WANT to purchase the TAOS Sensors from the UK fine, but the FindChips search engine [noparse][[/noparse]http://www.findchips.com/] shows that both Future Electronics, and Mouser have stock right here in the United States.
Regards,
Bruce Bates
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No problem. I wasn't trying to jump on you but clarify what I meant.
Like you, I won't tangle with someone who knows the job they do.
I am all in favor of afforable LIDAR. Especially when it can be attained by the average joe.
Regards
Michael