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Virtual throttle position after A/T disconnect

Started by JP59, Mon, 27 Oct 2014 20:22

JP59

I have a problem with my Throttle USB axis I would like to share. I use a Saitek Throttle axis and it is configured as "Thottles ALL" in the USB settings.

When I disconnect the A/T the virtual throttles do not come back in the hardware throttles position. I need to do a full displacement of the hardware throttles (initial position - MAX -- IDLE - wanted position) to get the control of the virtual throttles back on the full detent. If I do not follow this procedure, I do not have the control of the virtual throttle along the whole detent. Is it a problem with my throttle or do you have this problem with other models of throttles ? If not, is there a way to force PSX to read the hardware throttle position at A/T disconnect and force the synchronization of the virtual throttle.

I hope you understand this problem, not very easy to explain.

Hardy Heinlin

#1
This effect is intentional and is the logical consequence of using a throttle that has no servo.

It assures that there is no jump after A/T disconnection.

The inertia of the engines is great enough to allow a quick throttle movement to max or idle and back. This trick is faster than using an extra key or button for the resync.


Regards,

|-|ardy

JP59

Thanks Hardy for the quick reply.

Quote from: Hardy HeinlinThe inertia of the engines is great enough to allow a quick throttle movement to max or idle and back. This trick is faster than using an extra key or button for the resync.

Yes this is what I do actually. It has no consequences, as you said because of the inertia of the engines, but unfortunately it doesn't looks like "beautiful" to do such a movement.

Hardy Heinlin

To make it look more beautiful, you may slowly move your hardware levers to the A/T commanded position before you disconnect the A/T.

JP59

#4
Quote from: Hardy HeinlinTo make it look more beautiful, you may slowly move your hardware levers to the A/T commanded position before you disconnect the A/T.

I'll try that. Thanks for the advice  ;)

Jeroen Hoppenbrouwers

#5
That's an Airbus maneuvre! Aaaaaaaah!     :shock:

The many hours that I flew PS1-driven full flight deck sims without motorized throttles, we just kept the physical throttle roughly aligned with the virtual throttle, exactly to avoid the sudden jumps when you kick the A/T out.  If you don't have a motorized throttle, you motor yourself.  It becomes a second nature after a while and isn't really unnatural either. Compare it to the regular heading bug resetting to current heading.


Hoppie

JP59

#6
However, I understand why there is not synchronization at A/T disconnection (to avoid a throttle position jump), but I don't understand why I need to do a full zero-max displacement of the hardware throttle to get the virtual throttle full displacement capabilities back ? Why doesn't PSX reset virtual throttle position AND displacement limits after it detects the first hardware throttle movement ?

Suggested sequence example : see changes I suggest in italic

A/T disengage
Nothing happens until hardware throttle is moved (this is like it works actually)
Virtual throttle position synchronization with hardware position when movement is detected
Reset the virtual throttle displacement zone to full capability

This way it will prevent virtual throttle jump at A/T disconnection, but synchronize and reset its maneuver limits when the hardware throttle is moved, preventing to do the max-zero maneuver.

Hardy Heinlin

#7
Because:

a) USB noise may cause a jump when a jump is not desired, e.g. when the A/T disconnects due to a malfunction.

b) Sometimes I want to adjust the A/T commanded thrust just a little bit by a relative lever movement.

Getting a jump after first USB movement is exactly what I want to avoid.


|-|

JP59

I understand your arguments. However, if I want to modify my script and get direct throttle pots to network to synchronize my throttles at A/T disconnection, is it possible to write in Qs436 variable ? And where is the throttle displacement limits value stored if I want to reset it also via the network ?

Hardy Heinlin

Yes, you can write absolute lever angles to Qs436 and PSX's levers will jump to that angle.

kiek

#10
Hi Jean-Philippe,

The psxseecon variables that you can use are:

Control variables:
Qs436, Tla1                , 3700, [-8925..5000],
Qs436, Tla2                , 3701, [-8925..5000],
Qs436, Tla3                , 3702, [-8925..5000],
Qs436, Tla4                , 3703, [-8925..5000],

Information variables:
Qs434, ATActive            , 3434,          
Qs436, Tla1Virtual         , 4735,            , Qcode value
Qs436, Tla2Virtual         , 4736,            , Qcode value
Qs436, Tla3Virtual         , 4737,            , Qcode value
Qs436, Tla4Virtual         , 4738,            , Qcode value

From Qs434 psxseecon derives SIOC variable 3434 ATActive with values:
1 = AT is moving the virtual Throttle Levers, and
0 = AT is not moving the virtual Levers (BLANK or HOLD).
If ATActive = 1 psxeecon, will upon receival of a virtual Lever update from PSX, not sent the Hardware Throttle Lever variables to PSX (so the hardware is no longer dominant!).

The four variables, Tla1Virtual, Tla2Virtual, Tla3Virtual and Tla4Virtual, give the values of the virtual Throttle Levers. They can, if ATActive = 1, be used to set the hardware Throttle levers according to the virtual ones (for motorized throttles).

regards,
Nico

JP59

#11
Thank you very much kiek and Hardy. Just one more argument. Sorry for my insolent remarks  ;)  :

Quote from: Hardy Heinlina) USB noise may cause a jump when a jump is not desired, e.g. when the A/T disconnects due to a malfunction.

You can avoid this by allowing jump at first USB movement only if the A/T disconnect was commanded by the pilot. When the pilot disconnects the A/T he knows he has to monitor and command thrust settings himself.

Quote from: Hardy Heinlinb) Sometimes I want to adjust the A/T commanded thrust just a little bit by a relative lever movement.

You can still allow this with my proposition.

The solution I suggest prevents jumps in case of A/T disconnection due tu failure but will synchronize at first USB movement after a pilot commanded A/T disconnect. It will prevent USB plug & play devices users to do the max-zero manipulation after A/T disconnection.

Hardy Heinlin

Human disconnect, system disconnect.

5 seconds passed.

7 minuntes passed.

Mode confusion.

What was the last mode? Human disconnect, or system disconnect? Can't remember ...

Also ...

What is HOLD? Human disconnect, or system disconnect?

What is blank after IDLE? Human disconnect, or system disconnect?

I've tried your suggestion, Jean-Philippe. I tried it 18 years ago. I didn't like it :-)

tango4

All you have to do is develop an A320. Problem solved.
Now, you'd better start now, Hardy, you don't want to miss the 2022 release date  :mrgreen:

JP59

Quote from: Hardy HeinlinHuman disconnect, system disconnect.

5 seconds passed.

7 minuntes passed.

Mode confusion.

What was the last mode? Human disconnect, or system disconnect? Can't remember ...

Also ...

What is HOLD? Human disconnect, or system disconnect?

What is blank after IDLE? Human disconnect, or system disconnect?

I've tried your suggestion, Jean-Philippe. I tried it 18 years ago. I didn't like it :-)

Hardy, don't care about HOLD or IDLE modes,... All these features must remain managed as they are actually. My suggestion only concerns the action at A/T disconnection made by the pilot by pushing the A/T disconnect pads. My request concern a very precise situation. It could be a selectable option for people who operate PSX with non motorized throttles (I guess about 95% of us according to the price of motorized throttles). Just force USB axis and virtual throttles to synchronize when the pilot pushes the A/T disconnect pad and makes the first movement of the axis, that's it. If the pilot pushes this switch, he clearly wants to move the throttles himself, so I do not see where is the problem. It avoids the pilot to do an unrealistic max-zero movement to resynchronize the throttles.

cagarini

#15
Yes, would be great to have...

We sort of had it in PS1.

I really do not like to cycle the throttles either :-/

Wouldn't just a slight push / pull on the joystick axis assigned to all throttles be sufficient for the USB driver to sync with the virtual throttles?

pilotwannabe1

Another suggestion:  Have a temporary marker on the N1/EPR tape that shows the position of the physical thrust lever for a few seconds when the throttles are moved. This way, one can align the physical throttle with the current power setting before disengaging the AT, so that there is no jump. Of course, this could be a user selectable feature so the purist will not see anything on the EICAS that is not there on the real aircraft.

Rushad

Hardy Heinlin

#17
If I recall correctly, in PS1 the virtual throttle was synced with the joystick throttle only when the joystick throttle touched the idle stop. This way you were able to set idle during landing even when the joystick throttle was below the virtual throttle. This, and the same principle for the max stop, is something I might consider implementing in a future version.

After A/T disco, you move the hardware lever, and the virtual moves with it at the same rate. When you hit the max stop and the virtual is below max, the virtual will jump to max. That's what you want when you hit the max. And from there on they are in sync.

Or .... when your hardware lever hits the idle stop, and the virtual is above idle, the virtual will jump to idle. That's what you want when you hit the idle. And from there on they are in sync.

Before you hit the max or idle stop, relative movements are applied.

That's the only reasonable compromise I can imagine. I'm not happy with the other suggestions. I tested them a zillion times in the past.


|-|ardy

JP59

#18
I see one problem with this solution. Imagine a full throttle movement angle from max stop to idle stop of 100° (this is not the real value but 100 is easy for the understanding). Two scenarios :

The pilot wants to do a movement in the max stop direction :

Quote from: Hardy HeinlinAfter A/T disco, you move the hardware lever, and the virtual moves with it at the same rate. When you hit the max stop and the virtual is below max, the virtual will jump to max. That's what you want when you hit the max. And from there on they are in sync.

Imagine that the virtual throttle is at 10° and the hardware at 90° just before you disconnect the A/T. You have only 10° of hardware displacement available. Now you want to increase the thrust of, say, 20°. It becomes impossible because you only have 10° of hardware course available before to hit the max stop, and the virtual throttle to do an unwanted jump of 80°

Quote from: Hardy HeinlinOr .... when your hardware lever hits the idle stop, and the virtual is above idle, the virtual will jump to idle. That's what you want when you hit the idle. And from there on they are in sync.

The pilot wants to do a movement in the idle stop direction :

Same problem but reversed.

Quote from: Hardy HeinlinThat's the only reasonable compromise I can imagine. I'm not happy with the other suggestions. I tested them a zillion times in the past.

I see you don't want to allow the USB axis movement to synchronize the virtual throttle. In this case, why don't you imagine, for example, to allow a 3rd pressure on the A/T disconnect pad within a given delay to force the synchronization ? First press = A/T disconnection, second press = advisory cancel, third press = hardware and virtual levers synchronization. Of course it would be a user selectable option to allow users to use or not this feature. The lucky pilot who has a motorized throttle do not select this function. The others don't need to do an unrealistic max-idle movement anymore. Everybody is happy !

The third pressure on the A/T disconnect pad cannot be something other than a pilot deliberate action, and prevents synchronization coming from jitters or unwanted lever movement if this is what you don't want to happen with the sync by first USB axis movement solution.

Hardy Heinlin

In your first two points I see no problem: When the hardware hits the stop earlier than the software, and the software moves on, the offset will be squeezed to zero as the software moves on; vice versa, there will be a jump when the software hits the stop, but that's what you want: a jump, when the user intervenes.

Your third point, however: I think this is a good suggestion! I'll think about it ...


|-|