Help with DUSI

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Help with DUSI

Postby jlillest » Jan 24, 2011 10:08 pm

OK, I know there are several previous subjects on the DUSI, but I need some help with getting started with the DUSI.

First of all, I just received this DUSI which I believe is a v1 and would like to know the quick and dirty method for calibrating it. I'd also like to know how to download data to my computer (Windows).

Since the DUSI site is now down, this makes it harder to get info, but I was hoping that I could get enough info from experienced users to get started.

Thanks,
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Re: Help with DUSI

Postby jlillest » Jan 26, 2011 10:01 pm

Anybody have at least a manual to share?
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Re: Help with DUSI

Postby Crockett » Jan 27, 2011 2:21 pm

Jon, I will search my archives. I think I have the manual and the connection software and maybe some other stuff related to the DUSI. My server, which would have these files, is tied up in maintenance right now. Not sure when that is going to end. Looks like the tech on the other end of the remote went to sleep.

I think the DUSI calibration algorithms are horked. A coder might be able to fix it.

I will send the files to the yahoo address I have for you...after the tech wakes up and finishes...hey, he's back.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 5, 2011 11:43 pm

I would like to pull up this post because it appears to be currently dead and my questions are directly in line with the title of this forum.

I just bought a DUSI version 1 from someone who wanted to sell his because it was just setting around. Anyway, I'm not exactly sure how to properly align the instrument. The accelerometer calibration is self explainatory however, when the update flashes im guessing its just saying "okay you can move on to the next orientation"? Is that right?

The magnetometer is a little more difficult because im getting dip errors of over 5 degrees when the maximum allowed value is 1 degree. I did this inside so that may be the problem. I will do this outside when the weather gets a little nicer.

During laser alignment the instrument gives me a value to shoot for but how do you know that your even close to that value if the DUSI isnt showing the values that your currently at? If it does show these values, I havent figured out how to display them yet.

This information was probably all located on Sean's webpage at one time, but now that it's not active anymore it's not easy to find this data.

Anyone know where I can get a software update as well?
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Re: Help with DUSI

Postby Extremeophile » Feb 6, 2011 1:50 am

This is always a frustrating topic for those owning a DUSI. The original documentation was poor and the drivers for interfacing the device with a PC don't seem to work. I have a folder containing videos on how to calibrate the device, documents, drivers, etc., but it's 128MB. If you have a FTP site I can upload the data to send me a PM. Otherwise I guess you could PM me your mailing address and I'll send you a CD.

I have to warn you that mine is the version 2, and I'm not sure the drivers would be compatible anyway.

As for calibration, my unit has pretty simple instructions directly in the unit's menu system. In fact, probably the best documentation anywhere on how to use the DUSI is in the embeded "about" descriptions (usually accessed by pressing the "A" button). The general process is to lay the unit on a flat surface for a couple seconds until it stabilizes. Sean refers to these as "stillpoints". You get 3-4 stillpoints on each of the devices 6 sides (bottom, top, right side, left side, top edge, bottom edge). You end up with at least 18-24 stillpoints and then tell the unit to calibrate using these stillpoint values. You need to calibrate the magnetometer and the accelerometer, and then calibrate the LASER alignment. All of this calibration work needs to happen away from magnetic influences. The device seems to be ultra sensitive, so indoors won't work. Sometimes it seems the middle of the Alaskan wilderness is too close to interferences. The only good thing about it is you can do a full calibration in less than 5 minutes.

There are a number of settings you can access through the menus that may affect the sensitivity and stability of readings. I've planned to conduct a design of experiment (DOE) to determine the optimum combination of these settings, but haven't found the time. For the version 2 these settins are: magnetic range, accelerometer tolerance, magnetometer tolerance, joint still points, magnetic dip. Sean doesn't give much guidance here so I was going to figure it out myself.

If you use default settings you will probably find the same result that most everyone else has: clino calibrates extremely well and gives very precise results that are repeatable and give good agreement with Suuntos. The azimuth readings are a problem. Front and back sights can be 5 degrees or more off, and they change as you rotate the device.

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Re: Help with DUSI

Postby WVCaver2011 » Feb 6, 2011 10:23 am

So, basically I bought a clinometer that is acceptable in surveying but a compass that is not? I will try your approach for the calibration. Hopefully this works out well. I guess we'll see.

Thanks for the heads up. Looks like the more calibration shots you have the better. However, I cant figure out how to tell the device to calibrate itself after I take all the calibration readings. Any help with this?
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Re: Help with DUSI

Postby Extremeophile » Feb 6, 2011 9:07 pm

I don't think there's anything fundamentally wrong with the equipment. I've been told it's the same mag and accel sensors as the DistoX. Most people seem to agree that it's capable of giving both good azimuth and inclination readings, but there seems to be a bug in the latest firmware (which isn't all that late). Lynn Brucker did a lot of work with the DUSI and posted the results here:

viewtopic.php?f=26&t=7478&hilit=dusi

Lynn believes the older firmware worked pretty well and then an update (I think in May '09) screwed things up. If you search the forum archives for "DUSI" you'll get some more background, but not a lot of answers to help solve your current predicament.

Again, my unit is version 2, but from the main menu I select "6", which is calibration. In the next menu I select 2, 3 and 4, which are accelerometer, magnetometer and LASER alignment respectively. I then just follow the instructions to calibrate each. I believe version 1 menus are different so this may not help.

I've sent you a CD with all the files I have on the DUSI as well as some articles Lynn wrote on calibration of digital survey instruments. There's also a presentation given at the 2008 convention on digital survey. All good reading.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 6, 2011 9:26 pm

derekbristol wrote:I don't think there's anything fundamentally wrong with the equipment. I've been told it's the same mag and accel sensors as the DistoX. Most people seem to agree that it's capable of giving both good azimuth and inclination readings, but there seems to be a bug in the latest firmware (which isn't all that late). Lynn Brucker did a lot of work with the DUSI and posted the results here:

http://www.forums.caves.org/viewtopic.p ... hilit=dusi

Lynn believes the older firmware worked pretty well and then an update (I think in May '09) screwed things up. If you search the forum archives for "DUSI" you'll get some more background, but not a lot of answers to help solve your current predicament.

Again, my unit is version 2, but from the main menu I select "6", which is calibration. In the next menu I select 2, 3 and 4, which are accelerometer, magnetometer and LASER alignment respectively. I then just follow the instructions to calibrate each. I believe version 1 menus are different so this may not help.

I've sent you a CD with all the files I have on the DUSI as well as some articles Lynn wrote on calibration of digital survey instruments. There's also a presentation given at the 2008 convention on digital survey. All good reading.


The menu is exactly the same as you are mentioning. The only issue is the "manual". The A button tells about everything except how to update the calibration when your finished calibrating the device. What procedure to you use to finalize your calibration results for both the accelerometer and the magnetometer?
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Re: Help with DUSI

Postby Extremeophile » Feb 6, 2011 11:14 pm

Once I have the 18 or so stillpoints I just press "1" to calibrate. It calculates some constants (in units of %). That's where my understanding ends. I assume it uses these constants to convert whatever voltage or current reading it gets from the accelerometer or magnetometer into a corrected inclination angle or azimuth respectively. I'm not sure if it's important to do the calibration in a specific order or not. I've generally done accelerometer followed by magnetometer and lastly LASER alignment.

I've suspected that some of the problem with the magnetometer calibration has to do with sensitivity. The readings change very quickly and there appears to be a lot of noise. If your hand shakes a little as you're getting the measurement then maybe there's a significant amount of noise captured in the reading. When Lynn did her work she used a non-magnetic tripod and clamp to hold the instruments. This might improve the repeatability of the measurement.

I'm not much of an electronics or software guy, so I'm not going to be much help solving these issues. I'm pretty good with statistics and characterizing measurement systems, so I know how to handle the data.

Good luck and let the forum know if you develop a solution. There are a number of frustrated DUSI owners out there.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 7, 2011 12:32 am

derekbristol wrote:Once I have the 18 or so stillpoints I just press "1" to calibrate. It calculates some constants (in units of %). That's where my understanding ends. I assume it uses these constants to convert whatever voltage or current reading it gets from the accelerometer or magnetometer into a corrected inclination angle or azimuth respectively. I'm not sure if it's important to do the calibration in a specific order or not. I've generally done accelerometer followed by magnetometer and lastly LASER alignment.

I've suspected that some of the problem with the magnetometer calibration has to do with sensitivity. The readings change very quickly and there appears to be a lot of noise. If your hand shakes a little as you're getting the measurement then maybe there's a significant amount of noise captured in the reading. When Lynn did her work she used a non-magnetic tripod and clamp to hold the instruments. This might improve the repeatability of the measurement.

I'm not much of an electronics or software guy, so I'm not going to be much help solving these issues. I'm pretty good with statistics and characterizing measurement systems, so I know how to handle the data.

Good luck and let the forum know if you develop a solution. There are a number of frustrated DUSI owners out there.


I will do the calibration this week and see what I can find out. Im going to see if I can get a bunch of measurments in and hopefully that will make the magnetometer more precise but who knows. I will compare my final results with my suunto and see if it's relatively close.

Thanks for all the info and the CD!!! I hope this calibration problem gets resolved.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 8, 2011 10:41 pm

When you are done calibrating the DUSI, should you disable the autocal? I calibrated the DUSI's accelerometer a couple days ago and took a few shots and got an average error of .2 degrees. Today I turned it on and took the same shots and the error turned out to be around 2 degrees. I had the autocal on while I was shooting my shots. Could this be the problem or what is?
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Re: Help with DUSI

Postby Extremeophile » Feb 9, 2011 8:41 pm

Sounds like turning the autocal off might be a good idea. I don't think mine has that function.

I believe Lynn Brucker has recommended running calibrations on digital survey instruments about every 30 days. In another thread someone with a DistoX was doing it before every survey. Based on Lynn's suggestion I would expect the calibration and therefore readings to be reasonably stable for up to 30 days. If you are getting very different results from day to day then there's probably something else going on.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 10, 2011 4:45 pm

derekbristol wrote:Sounds like turning the autocal off might be a good idea. I don't think mine has that function.

I believe Lynn Brucker has recommended running calibrations on digital survey instruments about every 30 days. In another thread someone with a DistoX was doing it before every survey. Based on Lynn's suggestion I would expect the calibration and therefore readings to be reasonably stable for up to 30 days. If you are getting very different results from day to day then there's probably something else going on.


I guess it just depends on how accurate you want your measurements. I'll be calibrating my DUSI in cave and will see how well it goes and get back to you. I will take a suunto along just to check the calibration.
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Re: Help with DUSI

Postby WVCaver2011 » Feb 12, 2011 10:44 am

Wasnt able to find the cave the other night because our directions were't all that great. However, I was able to do a calibration outside ~20 feet from anything metal. I did my calibration on an old tree stump. I was able to get everything to work out fairly well as far as calibration goes. The accelerometer was reading 1.00 in nearly all orientations and the magnetometer was also reading 1.00 in nearly all orientations. My laser alignment had a .67 error which I suspect is fairly good.

Even after this I got front and back sight errors of around 3 degrees for BOTH the inclinometer and the compass. I then started asking myself questions...

1) The stump wasnt level, could that affect the measurements? Answer: I dont know. Only thing to do is test it and see but where am I going find a flat spot in West Virginia that's not magnetized. Usually the only flat spots are areas that have been leveled manually. I guess if I could find a horizontally bedded rock (once again, hard to find in WV) I could use it. The first thing I should ask you guys is: Does this have any affect on the calibration? Has anyone tested this?

2) Is there anyway to set the magnetometer to calibrate using more than 18 measurments? I would like to experiment with this and see if its possible to gain better measurments with the magnetometer if I can take more than 18 still measurements. Even though the magnetometer read 1.00 for nearly all orientations, there were a few places that I orientatated to that were not quite 1.00. Sometimes the accelerometer would read 1.05 and would not change to 1.00 after many still orientations. for some reason, it didnt seem to want to update itself. Was this do to the non-level surface?
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Re: Help with DUSI

Postby WVCaver2011 » Feb 12, 2011 6:51 pm

Well, I seemed to figure out what was going on. It wasnt the levelness of the calibration after all. You have the option to either put in the magnetic coordinates of the location being surveyed or the option to input the inclination, declination, and field strength. I origionally typed in the magnetic coordinates for my location but that didnt work out to well. I decided to input the other option and that REALLY made things a lot better. I was able to get anywhere from .9-.4 degree error on the compass without a steady hand, and a 0-.4 degree error for the inclinometer... It's funny how just little things with this device make all the difference. I'm going to test the calibration in a small cave that I need to survey anyway because it may become a new entrance to a much larger cave i'm working on.
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