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HomeAircraftHelicopterMain Discussion › Pitch Gauge or Main Blade Foldback for Setting Your Coll. Pitch
11-13-2014 02:23 AM  3 years agoPost 121
EEngineer

rrProfessor

TX

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do the math about your imaginary 6~9 axis gyro
Why do you say that a 6 or 9 axis gyro is imaginary?

They've been in production....

http://www.invensense.com/mems/gyro/nineaxis.html

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11-13-2014 02:30 AM  3 years agoPost 122
revmix

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spot-on

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11-13-2014 02:34 AM  3 years agoPost 123
EEngineer

rrProfessor

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mount...

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11-13-2014 02:35 AM  3 years agoPost 124
revmix

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Pitch Gauge or Main Blade Foldback for Setting Your Coll. Pitch
for you

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11-13-2014 02:38 AM  3 years agoPost 125
rexxigpilot

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Still only 3 axis gyro. The accelerometer and compass features give it 9 degrees of freedom: 3 for rotation, 3 for translation and 3 for positioning.

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11-13-2014 02:40 AM  3 years agoPost 126
EEngineer

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TX

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No, an accelerometer provides change of rate, in addition to rate.

FWIW

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11-13-2014 02:48 AM  3 years agoPost 127
rexxigpilot

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translation with respect to time. 9 DOF.

Remember the I in the PID loop.

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11-13-2014 02:52 AM  3 years agoPost 128
EEngineer

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TX

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Yeah, integration...but wasn't referring to an FBL loop.

Was referring to Invensense's technology in general.

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11-13-2014 05:39 AM  3 years agoPost 129
EEngineer

rrProfessor

TX

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What I meant was, rexx...

And, I'm in total agreesment with you on the accuracy of math...

But with regards to gyros in general, from what I know, is this:

Limiting the following to just 1 of the single axis MEMS gyros, used in an FBL cntlr...

They output rate of rotation(specs in that link), about a given axis.

With an accelerometer, those more advanced gyros also provide the rate of change of rotation about a given axis...while at the same time providing rate of rotation.

cont.

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11-13-2014 05:46 AM  3 years agoPost 130
EEngineer

rrProfessor

TX

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The "I" in the PID loop....infers integration.

Integration of your rate of rotation output results in "average rate of rotation"......which is not "rate of change" of rotation.

Rather than integrating, the "derivative" of the rate of rotation would more closely approximate such "rate of change" of rotation.

Being said, if one has the rotation rate data and the rotation "rate of change" data....the motion can be sensed more accurately.

As one has the rate...as well as the acceleration of the rate.

cont.

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11-13-2014 05:54 AM  3 years agoPost 131
EEngineer

rrProfessor

TX

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To take the farther, is the rate acceleration changing....or is it constant?

Now they can determine the rate of change of acceleration of the original rotation rate sensed....

Times 3 or 2, 9 or 6 axis gyro capability

So, to conclude...

3 axis = rate determination
6 axis = rate determination + rate acceleration
9 axis = rate + rate accel. + rate of change of accel.

It's all about sensing "motion", no matter what the application is.

FWIW

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11-13-2014 11:23 PM  3 years agoPost 132
rexxigpilot

rrProfessor

Florida

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The accelerometers measure linear acceleration not angular. The accelerometers are used to measure translation with respect to time: at = v, s = vt or 0.5at^2.

gyros = angular rate of rotation (angular velocity).
accelerometers = translation
compass = positional direction.

Therefore, 9 DOF. Still only three axis.

http://www.invensense.com/mems/principles.html

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11-14-2014 12:36 AM  3 years agoPost 133
Retired2011

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Lee's Summit, MO

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Got it!

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11-14-2014 12:41 AM  3 years agoPost 134
EEngineer

rrProfessor

TX

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I stand corrected...

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11-14-2014 12:53 AM  3 years agoPost 135
Retired2011

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Better than being mounted.

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11-14-2014 01:01 AM  3 years agoPost 136
EEngineer

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TX

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11-14-2014 01:31 PM  3 years agoPost 137
revmix

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stand corrected
XYZ
do the math about your imaginary 6~9 axis gyro
Why do you say that a 6 or 9 axis gyro is imaginary?
3D

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11-15-2014 01:15 AM  3 years agoPost 138
EEngineer

rrProfessor

TX

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Exactly...

With a 3-axis IC

The blue MiniVs use 3 separate single axis gyros arranged orthogonally to each other.

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HomeAircraftHelicopterMain Discussion › Pitch Gauge or Main Blade Foldback for Setting Your Coll. Pitch
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