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Autopilot feedback offsets for yoke-control


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I am working on building a realistic yoke-setup, which we are interfacing with FS via FSUIPC.

When the autopilot is switched on, we want to be able to move our yoke

according to the actions of the autopilot. E.g. turn the steering wheel

when the autopilot is going to a new heading.

I was hoping that "Elevator/Aileron/Rudder position indicators" (offsets, 0BB4,

0BB8 and 0BBC) would reflect the autopilot actions as well, but they don't (The

"Elevator/Aileron/Rudder control inputs" in offset 0BB2, 0BB6 and 0BBA, work fine

in normal flight-mode, which we use to inject our own yoke-sensor readings into FS).

The FSUIPC documentation mentions several autopilot features that have been added into

FSUIPC, but I am not sure if there are any control-surface related offsets, which reflect

the autopilot actions we need.

Do you know of any offsets, that are more suitable to derive yoke-positions

from, when running the auto-pilot? Is there perhaps a feature in FSUIPC that

takes care of this (which I don't understand yet).

We appreciate any help/tips/suggestions you can offer!

Kind regards,

Steven.

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Do you know of any offsets, that are more suitable to derive yoke-positions

from, when running the auto-pilot?

The aileron and elevator position indicators (0BB8, 0BB4) should help. Or you'd need to use the actual deflection angles, 2EA8 for Aileron, 2E98 for elevator. All these work fine with the autopilot in FSX, and should be okay in FS9, though you'd need to check that.

Regards

Pete

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Do you know of any offsets, that are more suitable to derive yoke-positions

from, when running the auto-pilot?

The aileron and elevator position indicators (0BB8, 0BB4) should help. Or you'd need to use the actual deflection angles, 2EA8 for Aileron, 2E98 for elevator. All these work fine with the autopilot in FSX, and should be okay in FS9, though you'd need to check that.

I tried these offsets before. (I am using FS2004). If you fly yourself with the joystick the offsets change/work fine. However after the autopiliot takes

over they are no longer updated. (E.g. elevator position indicator and elevator deflection become 0, even though there is a clear pitch while the

autopilot makes the plane climb).

Do you have any other suggestions?

Thanx!

Steven.

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I tried these offsets before. (I am using FS2004). If you fly yourself with the joystick the offsets change/work fine. However after the autopiliot takes over they are no longer updated. (E.g. elevator position indicator and elevator deflection become 0, even though there is a clear pitch while the

autopilot makes the plane climb).

I've just checked them on FS2004 -- the 0BB8 and 0BB4 values simply stick at their last manual value (they don't go to 0), but the deflection values at 2EA8 and 2E98 are working fine, and change correctly exactly as they do in FSX when on A/P control.

Please check again. Use the Monitoring facilities (right-hand side of the Logging tab) or FSInterrogate. You must be doing something wrong if you only see zeroes. Don't forget those deflections are in Float64 format.

Pete

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Hi Pete,

I tried these offsets before. (I am using FS2004). If you fly yourself with the joystick the offsets change/work fine. However after the autopiliot takes over they are no longer updated. (E.g. elevator position indicator and elevator deflection become 0, even though there is a clear pitch while the

autopilot makes the plane climb).

I've just checked them on FS2004 -- the 0BB8 and 0BB4 values simply stick at their last manual value (they don't go to 0), but the deflection values at 2EA8 and 2E98 are working fine, and change correctly exactly as they do in FSX when on A/P control.

Please check again. Use the Monitoring facilities (right-hand side of the Logging tab) or FSInterrogate. You must be doing something wrong if you only see zeroes. Don't forget those deflections are in Float64 format.

Pete

Thank you for the tip. I tried the logging and I think I found the problem.

When I fly with a joystick, the joystick will always take priority

over the autopilot, when controlling the deflection.

So a joystick in neutral position will push the deflection to 0.

(However the simulation internally makes the plane climb, if the autopilot

altitude requires a climb). When I fly with the keyboard (joystick unplugged)

then the autopilot seems to be in total control of the deflection.

When I use offset 310A to turn off the joystick axis, then it works

better. (I tried this before unsuccesfully, due to a bug in the code I made).

What is really strange though, is that even with the joystick disconnected

from the elevator-axis, I can still control the deflection (2E98) in a very small range

(up to 0.025 deflection value). When I turn off the autopilot (at which

time the joystick axis is attached again via offset 310A), the joystick gets

total deflection control again.

I am using FS9.1 and FSUIPC 3.7 on Windows-XP SP2. I am flying a 737-400.

Do you have any suggestions?

Are there any other tests I could do to tackle the problem?

Thanks a lot for any help you can provide!

Regards,

Steven.

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When I fly with a joystick, the joystick will always take priority

over the autopilot, when controlling the deflection.

Doesn't that depend on how the joystick values are being injected? Do you really mean the actual visible control surface deflection, or just the numbers which would represent the deflection if the A/P were disconnected? I'm not sure what you are getting at.

What is really strange though, is that even with the joystick disconnected

from the elevator-axis, I can still control the deflection (2E98) in a very small range

(up to 0.025 deflection value).

Not sure why that would be. Is 2E98 reflecting the true control surface deflection?

I am using FS9.1 and FSUIPC 3.7 on Windows-XP SP2. I am flying a 737-400.

I don't support old versions of FSUIPC. Please update to a supported version before asking any further questions.

Do you have any suggestions?

Are there any other tests I could do to tackle the problem?

Sorry, you don't seem to have stated any problem, only observations on how FS behaves. What do you think is wrong?

Please update your FSUIPC before coming back, and please note i am away after today until June 10th.

Pete

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Hi Pete,

The joystick is connected to FS2004 via windows (like any game; no software of mine is in between).

The problem I meant to state was that even though I used offset 310A to disconnect the joystick

from the elevator, I can still make the deflection value change just a tiny little bit by moving the joystick.

I tested this in a situation where the elevator deflection was 0 (flying straight ahead).

I viewed the elevator deflection offset (2E98) in the FS title bar (via logging in FSUIPC).

I was just wondering if you had any idea what the reason could be.

Regards,

Steven.

PS. I will update to the latest version of FSUIPC asap.

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The problem I meant to state was that even though I used offset 310A to disconnect the joystick

from the elevator, I can still make the deflection value change just a tiny little bit by moving the joystick.

I tested this in a situation where the elevator deflection was 0 (flying straight ahead).

I viewed the elevator deflection offset (2E98) in the FS title bar (via logging in FSUIPC).

I was just wondering if you had any idea what the reason could be.

No idea, sorry. Is the actual elevator affected. or only the offset?

Regards

Pete

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  • 3 months later...

Dear Peter,

I seen the problem for the elevator range with autopilot engage but I don't know if you can do any thing about that.

In flight simulator, the autopilot system manage only the trim command and to do that, the autopilot system move the elevator to 0.

Something strange from Microsoft because on real aircraft, trim adjust the elevator deflection to control the attitude of the aircraft and not control the aircraft directly...

So I'm trying also to build a force feedback but with this condition it's not possible.

How can I ask to the autopilot to manage the elevator and not the trim?...

Best regards

Phil

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So I'm trying also to build a force feedback but with this condition it's not possible.

How can I ask to the autopilot to manage the elevator and not the trim?...

Short of writing your own autopilot (or at least the Vertical parts), you can't. But I'm not sure what the problem is for "force feedback". Can you explain what sort of "force feedback" you are attempting and why it is impossible?

Regards

Pete

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Hi Pete,

I want just connect an electrical motor like servo to move a beech 90 yoke following the deflection of the ailerons and elevator.

the normal working procedure in a real aircraft:

In autopilot mode, the elevator yoke deflection follow the DV or the autopilot command and the elevator trim have to move just to reduce the "force" from the elevator motor.

In flight simulator, in manual mode, everything working fine because the deflection follow the yoke, but in autopilot mode, the elevator go to 0 and don't move any more. so if I want to connect the elevator motor, nothing happened for the elevator, just 0 centering.

I'm pilot and it's very strange for my to see trim moving without elevator deflection following it...

For information, if we move the yoke during the autopilot is connected, flight simulator make the correction for all deflection follow the autopilot and not the yoke, that resulting an offset between yoke position and deflection. On real aircraft we have cable between yoke and flight control, and it's not possible to have any difference between both during the flight...

So for me, the priority have to be on yoke and not on the autopilot in any mode, but I think it's Microsoft problem, not your ;-)

Best regards

Phil

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I want just connect an electrical motor like servo to move a beech 90 yoke following the deflection of the ailerons and elevator.

But the trim has an effect on that too -- if the aircraft is out of trim the force should be greater , no?

Why not read both aileron and trim and use the combination -- especially if the A/P is engaged, as that, as you say, is operating the trim.

In autopilot mode, the elevator yoke deflection follow the DV or the autopilot command and the elevator trim have to move just to reduce the "force" from the elevator motor.

In flight simulator, in manual mode, everything working fine because the deflection follow the yoke, but in autopilot mode, the elevator go to 0 and don't move any more. so if I want to connect the elevator motor, nothing happened for the elevator, just 0 centering.

Yes, so, in autopilot mode, use the trim read-out instead. Right?

Regards

Pete

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Hello Pete,

Yes why not, I have to think about that, I will let you know. I have think already tu control the aircraft in flight simulator only with the trim but I have to check about the realism for that, I'm not sure.

But the problem with the priority between the pilot and the autopilot still the same or I organize my software for disconnect the autopilot if the pilot move the yoke, why not...

Regards

Phil

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... or I organize my software for disconnect the autopilot if the pilot move the yoke, why not...

That would be normal, I think, at least if it moves more than a certain amount (allowing for some jitter and accidental small moves when pressing a yoke button).

Regards

Pete

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