FSSB resistance: How to be hated in 1 message ;)

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kerdougan
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FSSB resistance: How to be hated in 1 message ;)

Post by kerdougan » Sat Dec 20, 2008 7:45 pm

Hi everyone!

I've red all the threads reporting to the FSSB in your forum, I use this marvelous device since 5 months now and I really love it. It was pretty hard at the beginning but with time and by reading your topics I learning many things so first, I'd like to thank for all your efforts.

However I've got a bad news about your lbs calculation method, I think you are wrong :oops:

You've forgotten to consider an essential thing in your math: the calibration file! I looked in every part of your forum and you don't speak about it anywhere. To me it's the only accurate way to set your FSSB properly. If you open the CCP and look at the "Axis shaping" tab you can see the calibration neutral values. Mine is 32300 for the X axis. Now go to the Y axis, mine is 32300 too. Where does those numbers come from? The manual calibration file tells the Cougar to which point he will consider your efforts on the stick. The file is here: C:\Program Files\HOTAS\calib\ and mine is called "calibration.ccf" and it can be edited with the notepad.

Here is what my calibration file look like:

[Calibration]
0=18700,32300,45900
1=12300,32300,52300
2=41472,32000,23104
3=42880,34976,25024
4=14144,30720,47296
5=11008,31728,52448
6=52448,32288,11008
7=0,0,0
8=0,0,0
9=0,0,0
AxesStatus=2

The "0" line is for the X axis, the "1" line is for the Y axis, the "2" line is for the Microstick X. How do I know that? Simple, get back to the CCP "Axis shaping" tab and click on the "Axis to set" field. They are in the same order.

Now lets talk about all those numbers:

0=18700,32300,45900
X axis=max left value, neutral position value, max right value

1=12300,32300,52300
Y axis= max push value, neutral position value, max pull value

The Cougar works in 16bits, which means that each axis works with 65536 values. And 65536/2 gives 32768. It's not exacty between 32200 and 32400 but it's too close for being a coincidence. Remove the 00 at the end of those two last number and you'll have the settings Real Simulator ask to set with the screws under the sensor.

My opinion (and I've tested it too much for making mistakes about that) is that when you check your axis with the Foxy's joystick analyzer, you don't only compare it the FSSB resistance but also with the calibration file.

I only work with the max resistance (25/17) so I don't know what it would give with weaker ones. Off course, the 25lbs are between the neutral position and the max force the device can measure.

Let's consider my pulling settings: 1=12300,32300,52300

Max device value: 65536 = 100% measurable strength = 25lbs
Max pull calibration value: 52300

By doing my math I see that 52300 represents 79,80% from 65536, so 79,80% from 25lbs gives 19.95lbs for the pull.


Now I do the same thing for my X axis. I'll do it with the max right value = 45900 = 11,90lbs.

Oh crap, the 0.68 ratio isn't respected :( For having a proper one I should have 19.95*0.68=13.566lbs

So, lets get back to my actual right max value which is 45900. It will need to be increased, but how?

As I am writing those lines I understand an interesting thing: My resistance settings are 25/17 and if divide 25 by 17 it gives me 0.68. So if I set same value for my X and Y axis that will perfectly match the 0.68 ratio!

In the end if I want to have a proper 0.68 ratio using 19.95lbs for max pulling, 13.566lbs for max left and right roll I need to have:

0=12300,32300,52300
1=12300,32300,52300


By the way, since I have my FSSB I've always worked by editing my calibration file. Sometime it make your Cougar a little buggy after too many calibration file changes. You'll maybe have to flash it but that's not a big problem if you know how to deal with flashing.


Now that I've tried to prove that your calculation method was wrong, it's time for you to insult me :mrgreen:

PS: I know my method isn't 100% accurate but it must be very close from the right numbers!
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Burner
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Post by Burner » Sat Dec 20, 2008 8:59 pm

Great post Kerdougan, only thing I'm going to look into further is whether having a center point other than 32300 affects the FSSBs max/min possible values. I would think if my center point was way off, say 22300 to exadurate, my max possible upper setting would be 64536.

To followup, the method of setting poundage outlined in the FSSB thread is still correct so long as you max out each axis direction, but that rarely happens so however far off you are from 0 and 65536 your calulations will correspondingly be off.
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Post by kerdougan » Sun Dec 21, 2008 4:29 am

I agree that my method requires a few conditions for working, the best and simplest thing would be to have something like 1000 values on X axis = XXlbs for example.

The thing that really bothers me is:

Must I consider that the values go from 0 to 65536 with a real neutral point at 32768.

or

Must I consider that the values go from 0 to 64600 with a real neutral point at 32300.

After a little "two handed" test here are the results:
0=0,31888,62736
1=2,28738,62728

I did it very quickly so forget about the neutral values. What is important is the minimum values 0 and 2, and the max values 62736 and 62728. Lets consider that the real min is 0 and the real max is 62740.

62740/2=31370

I don't know why Real Simulator recommands to have a default value between 32200 and 32400. It would mean that the max values would be between 64400 and 64800 which can't be true, the sensor can't lie ;)

Today I'll turn the screw for having something around 31370 as default but what can already be said is 25lbs = 31370 values. And we could consider that

For X axis with 17lbs resistance:
1lb=~1845 values

For Y axis with 25lbs resistance:
1lb=~1255 values

Which means the number from my original posts are wrong because it considers 32300 as neutral value and 65356 as max. I think the new ones are much more accurate and don't need to have a neutral value correctly set.

0=18700,32300,45900 = 7.37lbs
1=12300,32300,52300 = 15,93lbs

Wow! Too bad for my weak arms :shock: Maybe I should think about taking a littler resistance :lol:


One thing I don't get about your message:
I would think if my center point was way off, say 22300 to exadurate, my max possible upper setting would be 64536.
Why 64536?
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Post by Burner » Sun Dec 21, 2008 1:44 pm

32300-1000 = 22300

65536-1000 = 64536
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Post by kerdougan » Sun Dec 21, 2008 2:34 pm

Burner wrote:32300-1000 = 22300

65536-1000 = 64536
Wouldn't it be 32300-10000=22300 and 65536-1000=64536?

Anyway, it doesn't work that way. As long as your default value is set accordingly to the screw it can be anywhere.

You could have 0=00010,00200,47000

You would have a very short left and a veeeeeeeeeeeeeeeery long right but it would work anyway. Unusable because the littlest move to the left would make your rollin' and rollin' and rollin' and you would need your two hands for going to the right.
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Post by Lawndart » Sun Dec 21, 2008 3:08 pm

Whenever I calibrate I always go to the max registered value, but not beyond it (if using the FSSB). With the stock Cougar (or NXT) you wouldn't be able to go beyond the max deflection because of the hard stop by the gimbals, but with the FSSB this is theoretically possible. I've always calibrated up to, but not past the limit of the reading in the software. Secondly, the center value is likely based on how your stick is positioned or mounted, taking into account the weight of the handle excerting a small amount of force "hands off". Having an absolute center of 32768 might not be an accurate center for a stick that sits canted forward on its mount for instance, or on one that's not perfectly level. The FSSB is so precise that any minor tilt angle in the stick would cause a center value different from the absolute "theoretical center", simply by the weight of the handle itself. That being said, the most accurate center value for you may be different depending on how your HOTAS is mounted and how level it is?

In short, as far as I can tell Kerdou's theory is likely true, but at the same time, (assuming a "valid" calibration), our resistance calculations are also correct. The basis for them to be correct are made on the entire range (no more AND no less) of the calibration values having been accurately completed to begin with.

I'll let the two of you geek out over this further, but just wanted to throw in some food for thought and brainstorm! :P
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Post by Burner » Sun Dec 21, 2008 4:16 pm

Heh yeah 10,000 missed a zero there.

I tilt my FSSB forward so the center is never where it should be, but that's ok I just have more y-axis pull range.
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Post by kerdougan » Sun Dec 21, 2008 4:39 pm

Lawndart I just hate you. :mrgreen:

[Geek mode=ON]
I don't get a thing about your calibration method.
Lawndart wrote:Whenever I calibrate I always go to the max registered value, but not beyond it (if using the FSSB). With the stock Cougar (or NXT) you wouldn't be able to go beyond the max deflection because of the hard stop by the gimbals, but with the FSSB this is theoretically possible.
What registered value are you talking about? Even if that's a non-physical sensor it has its limits just like the hard stop for the gimbals. That's why I demonstrated that the max value on X and Y axis is about 62740.

I agree about how the stick is mounted and its influence on the sensor. However it's balanced by the central deazone and you VTB guys are very generous on it. 10% is a big one, I made a few tests a while ago and this influence can be felt under a 4 or 5% deazone. Once you start pulling on the stick during a flight, I don't think it matters anymore.

[Geek mode=OFF until your next answer :p]

The point is that I think I've never get that you pushed the FSSB to its limit during your calibration. Maybe I simply didn't get it, maybe it wasn't written but it doesn't matter. On my side I just calibrated for what my arm was able to give and started to work from here. The manual calibration in itself is too subjective to be accurate and I don't think everyone is ready to spend time as much time on it as we do. So, maybe you and I could create a little documentation about all this stuff (after a few more tests for validation), anyone interested in aerobatics (or else) would be able to set his FSSB properly. There are 2 ways to do it, lets explain both of them in that documentation and if we find out a few more things on the way lets explain it too! Interested?
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Post by Lawndart » Tue Jan 20, 2009 9:31 pm

Burner, Bueller... :? This one's all you, thought you'd be in calibration heaven by now! :lol:

@kerdougan, what I meant by "registered value" is when you calibrate you are in fact writing the raw values (you are referring to), they don't exist yet (as far as the calibration is concerned). Therefore, if you pull way harder on the stick than it takes for the on-screen value to reach its max (range of 0-648) you could theoretically be calibrating a stop that's beyond that point. That's what I meant by going up to the max "registered value", but not beyond it (i.e. not using any more force than it takes to "hold" 0 or 648 on the calibration scale in CCP). If this is true or not, I'll let the rest of you geek out about, but I hope that explains my train of thought.

Enjoy the geek-fest!
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