Originally Posted by jj604

For what it's worth I flew it for the first time today.

Results were fine but I only got in one flight clearly need to do more work on the gains and tuning.

The twin outputs on each axis are great for simplifying setup!

I also wonder if it would be an idea to have it set up out of the box for a "conservative" set of gain defaults instead of mid-range as at present.

That is:
Analog servos
Moderate gain on Roll
Low gain on Pitch
Nothing on Yaw

Then folks can start adjusting things to suit their particular needs, but if they just plugged it in and fly they couldn't go far wrong. Starts out as a conservative roll and pitch damper and move on from there.

Just a thought.

John

Hi John,

We'll take a look at that, for sure we're changing default to Analogue servos. What plane did you do your first flying with?
Mark

Just my beat up old Bixler. It does duty as the test bed for new technologies. It has wheels, a 2200kV motor and 6x4 prop so it has a just enough go to test for oscillation but a nice disposition power off so it is a good place to start with anything new. It also puts up with a lot without complaining.

Originally Posted by IceManPro

Hi John,

We'll take a look at that, for sure we're changing default to Analogue servos. What plane did you do your first flying with?
Mark

BL-3GRC positioning in a fixed-wing aircraft

Mark - Is it necessary to place the gyro at the CG?
What happens if we don't?

I guess the idea is ideally to have the gyro at the centre of roll and the centre of pitch and the centre of yaw, although these will in practice not coincide.

Consider the six degrees of freedom of movement: three of rotation and three of translation.
Will the gyro be affected at all by translational movement?

Consider just pitch.
What happens if the gyro is placed three inches behind the CG?
(Or three inches behind the pitch axis.)

When the plane suffers a pitch disturbance, the gyro will move up or down to an extent dependant on its distance from the pitch axis.
But the amount the gyro rotates will be the same - no matter how far the gyro is from the pitch axis.

So ... does it matter where we put the gyro?

chris, gyros detect angular displacement not linear displacement.

As far as I know they can be mounted a reasonable distance from the CG without adverse effect since the angular displacement is unchanged. That is if the plane pitches by 5 degrees, the actual distance through which the gyro moves is not the thing that is measured but the angle it tilts by.

This is is not true of stabilizers which include accelerometers like the Eagletree Guardian or the forthcoming Blue Light Pro of course.

Be interested if BlueLight have made any measurements of what actually happens however. Theory and practice aren't always the same.

Originally Posted by chris3142

BL-3GRC positioning in a fixed-wing aircraft

Mark - Is it necessary to place the gyro at the CG?
What happens if we don't?

I guess the idea is ideally to have the gyro at the centre of roll and the centre of pitch and the centre of yaw, although these will in practice not coincide.

Consider the six degrees of freedom of movement: three of rotation and three of translation.
Will the gyro be affected at all by translational movement?

Consider just pitch.
What happens if the gyro is placed three inches behind the CG?
(Or three inches behind the pitch axis.)

When the plane suffers a pitch disturbance, the gyro will move up or down to an extent dependant on its distance from the pitch axis.
But the amount the gyro rotates will be the same - no matter how far the gyro is from the pitch axis.

So ... does it matter where we put the gyro?

Originally Posted by chris3142

BL-3GRC positioning in a fixed-wing aircraft

Mark - Is it necessary to place the gyro at the CG?
What happens if we don't?

I guess the idea is ideally to have the gyro at the centre of roll and the centre of pitch and the centre of yaw, although these will in practice not coincide.

Consider the six degrees of freedom of movement: three of rotation and three of translation.
Will the gyro be affected at all by translational movement?

Consider just pitch.
What happens if the gyro is placed three inches behind the CG?
(Or three inches behind the pitch axis.)

When the plane suffers a pitch disturbance, the gyro will move up or down to an extent dependant on its distance from the pitch axis.
But the amount the gyro rotates will be the same - no matter how far the gyro is from the pitch axis.

So ... does it matter where we put the gyro?

Below are pictures of the Eagletree Guardian placed 6" behind the CG. It still works great.

Originally Posted by chris3142

BL-3GRC positioning in a fixed-wing aircraft

Mark - Is it necessary to place the gyro at the CG?
What happens if we don't?

I guess the idea is ideally to have the gyro at the centre of roll and the centre of pitch and the centre of yaw, although these will in practice not coincide.

Consider the six degrees of freedom of movement: three of rotation and three of translation.
Will the gyro be affected at all by translational movement?


Consider just pitch.
What happens if the gyro is placed three inches behind the CG?
(Or three inches behind the pitch axis.)

When the plane suffers a pitch disturbance, the gyro will move up or down to an extent dependant on its distance from the pitch axis.
But the amount the gyro rotates will be the same - no matter how far the gyro is from the pitch axis.

So ... does it matter where we put the gyro?

Chris,

Here is a Guardian mounted 6" behind the CG. It is still working great.

Bill

Originally Posted by jj604

chris, gyros detect angular displacement not linear displacement.

As far as I know they can be mounted a reasonable distance from the CG without adverse effect since the angular displacement is unchanged. That is if the plane pitches by 5 degrees, the actual distance through which the gyro moves is not the thing that is measured but the angle it tilts by.

This is is not true of stabilizers which include accelerometers like the Eagletree Guardian or the forthcoming Blue Light Pro of course.

Be interested if BlueLight have made any measurements of what actually happens however. Theory and practice aren't always the same.

HI Chris,

It's not that critical, the impact on the gyro with translational motion is very small. You can go to the tools page of the set up software and press the "test" button. You can see the green bars moving, if you move the gyro in translation it will show very little displacement, ie when you slide the gryo rather than rotating it. The effect of not mounting at exactly the centre of gravity just means it will not be so accurate in picking up the angular rotation, if a long way off you can just increase the gain a touch for that axis.
Mark

Gentlemen,

Just wanted to tell you all that this thread's posts are of great benefit to me - an old Engineer just srarting to explore the new technology available to me! (I am still, I fear, better at reversing servos with mechanical linkages!)

The clear, concise and correct language here is indeed a treat!

Happy flying and tinkering,

Mike Horton

Gyro Corrections Reversed?

I've hooked up the BL-3G in my plane, still on the bench.
The wings are off, and I'm just testing the gyro with the rudder and elevator connected.
The plane has successfully flown before.

With the gyro On, and I suddenly yaw the plane so the tail moves to the right, the rudder should move to the right also.

However, the rudder moves in the opposite direction.

The same goes for the elevator.
If I move the tail down, the elevator comes up.

How do I reverse this?

I didn't test the ailerons yet, although they may correct backwards also.
I have not adjusted any gain controls yet.

Ted

Hi Ted,
If the rudder and elevator move correctly with the sticks (ie the same as if the gyro were not there), then the only thing I can think of is that you have the gyro mounted up-side-down on the plane. (the gyro needs to be mounted facing up). In this case the yaw and elevator will be incorrect, but the ailerons will be ok. Please confirm. We will support up-side-down mounting in the next release due before the end of this month.

(FYI we now have v1.9 of the user manual. The max servo power has been corrected, incorrectly set too low in the previous manual versions)

IIceManPro:

All the flight controls, using the sticks, move in the correct direction.
The gyro is definitely mounted right side up, and forward.

I was bench-testing your gyro without the wings on because it's very hard to see and get into the under-canopy area once the wings are on.
The input wires (from receiver to BL-3G wires were left connected).
The output wires (3&4) were not connected in this case while wings were off.

However, I found out something very interesting, and odd.

I put the wings on, all hooked up.
Flight controls move in proper directions with sticks.

NOW, the BL-3G makes corrections for PRY in the correct directions!

I then took the wings off and disconnected the wires for them (Outputs 3&4).
Now, again, the rudder and elevator corrections are backwards!

So, without having the wings connected, the gyro outputs reversed corrections for rudder and elevator.

Hmmmm, wonder what would happen with a plane that had no ailerons?
Maybe it would be OK in this case if the input wires were not connected?

Anyway, problem solved. Just have to have all controls connected.

Ted

Ted, this seems very odd, can you tell me which f/w and s/w versions you have installed? Do you also notice the same issue when looking at the blue and green bars on the tools page? I advise not to fly unless you're sure the system is all working fine.

Firmware is version 13.
PC Tool version 1.6.

The Blue and Green bars go in opposite directions when moving the plane/gyro.

I'll experiment more in an hour or two.

Ted

Originally Posted by Ted M

Firmware is version 13.
PC Tool version 1.6.

The Blue and Green bars go in opposite directions when moving the plane/gyro.

I'll experiment more in an hour or two.

Ted

Ted, Please update to v1.4 of the firmware. It is important to always have the latest version. Please see Bluelight-tech website and FAQ for details how to update. Also, I see a scenario where you may get the gyro operation opposite to expected. The BL-3G ICE-MAN Gyro assumes positive yaw as a clockwise motion. hence if it detects a counter clockwise disturbance it will act so as to counter this by increasing the rudder signal, to give clockwise motion. However, if you have your sticks giving less signal to generate a clockwise motion then the gyro will still detect a counter clockwise disturbance and add some signal. With this set up the addition of signal will cause the rudder to produce a counter clockwise motion instead.This can be fixed by adjusting the invert functions of your RC transmitter, then using an inverted Gyro output as necessary (I've just tried it and it works). However, in the next s/w releases we will give the option to simply reverse the gyro operation for either pitch, roll, yaw to save this messing about. This does show that its' very importat to check the gyro motion is as expected for disturbances.

Mark

Has anybody used this on a quad