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imflabulous
Posts: 2
Hello! This is my first time on the forums and I hope everyone's doing well.

I've been wanting to get into DIY stuff for a while and I thought to use this spare time during quarantine to start. I'm pretty unfamiliar with how all this works so I apologize if I don't understand right away.

I basically want to create a motorized throttle quadrant for use with the PMDG 777. I already have an idea of how everything will work mechanically: A servomotor will be connected via a small electronic clutch to a throttle lever, which is then connected to a rotary potentiometer to read angle data. The clutch is turned on when A/T is engaged (except in HOLD mode) and the servo can control the angle of throttle lever. But when A/T is disengaged or in HOLD mode, the clutch turns off and the throttle lever can be moved by hand independently from the servo (moving a servo by hand can damage it). But servos can't be moved 360°, so I also need to make the servo follow the angle of the throttle lever as I move it.

A motorized speedbrake lever will also be present but that seems much easier to do given the servo only has to rotate the lever to its fully-extended position during touchdown and that's it.

Thing is, I'm not sure exactly how to start programming this. If this quadrant were not motorized, this would be a lot easier because it's all input and I just need to map the correct axes to FSUIPC (I think). But since it's motorized, it needs to take data from the simulator (specifically the instantaneous throttle lever position), drive servomotors to achieve a desired position and also engage/disengage the clutch.

Supposedly MobiFlight can be used to interface an Arduino Mega with FSUIPC so I thought this could be a possible starting point, but I really don't know how it all comes together. Any help for a DIY newbie would be greatly appreciated :)

Thanks!
2020-05-06 17:54
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pizman82
Moderator
From: ETSI, Germany
Posts: 4465
Supporter
Hi

At first i recommend the SEARCH Function..... Whatever nobody do this for B777..... Lots of attempts to build this with B737 was done already.... throttle is the same. So Solution is the same.

Then let me say this is a big step ! Buidling a motor Throttle is maybe the most advanced part in a cockpit. To do this you should have already a lot of knowledge about mechanics and also about usage of Mobiflight.

Whatever.... Most Users make a system ( much more easy) without a clutch..... based on a "unpower" relais for the Servo..... Means you move the throttle by hand and also move the servo that time BUT in that Moment the Servo is not powered so this is not a problem..... Otherwise if AP is active then the servo is also activ.... BUT then we are not allowed to touch the throttle cause so we would "override" the Servo. .... Means we must define 2 clear Situations.... Servo ON and Servo OFF

To handle a "Hold" or "rejected takeoff" situation the main idea is to build a little Button into the throttle so it simply disconnect the Servo if we touch the Throttle ( Maby by pressing it 1mm down in case of the weight of our hand on it..... Or by a contact in the lever that detect our hands.

Your glutch logic sounds better..... but here we pretty sure get a sync problem.
The Servo must be ( in moment of activation by the glutch) in the exact same position like the real lever.... We be able to "read" this position and to run the servo that way..... BUT there is a delay.
On first view i would say this is posible but the throttle must be in that position for 0,5-1 sec for the "transfer" ..... This need to be tested.

To help you we must figure out your mechanic planings.... then we can think about configs.

Last Note: If you can programming then think about a external solution. Maybe its possible with Mobiflight in a good way.... But pretty sure a self written programm and suing of Hall sensors is more profitable !
Good Luck !
2020-05-06 19:34
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imflabulous
Posts: 2
Thank you very much for the advice! I have a couple questions though.

I thought moving a servo by hand (even when unpowered) can damage it? I'm planning to use a small SG90 motor for each lever. But if it doesn't get damaged, then that definitely avoids the sync problem you mentioned and simplifies things significantly.

Also, can I actually make custom programs on MobiFlight to handle these servo on/off or clutch on/off situations? For example, is it possible to make a program on MobiFlight to turn off the servo when A/T is off or in HOLD mode? If I just use the Arduino IDE, I'm not sure how it can receive data from the simulator, like what A/T mode the aircraft is in and the throttle lever position.
2020-05-07 06:34
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pizman82
Moderator
From: ETSI, Germany
Posts: 4465
Supporter
Hi Again

I can not garantee your servo get not demaged.
I think same way like you but some users here still build those things and report they can move the Servo ( if unpowered) without problems. Sure we talk about sensetive moving and not pull it with full manpower in 0,5 sec from Full to Idle.
Pretty sure a factor is the servo itself..... Cheap servos with a plastic gear may be demamged more easy like epensive servos with a solid metal gear.


About Programms.

Technical you can write a own progromm with Arduino IDE ( and a additional programm on the PC that do the comunication between FSUIPC and Arduino) ..... But here i not have experience..... Techncial you must create your "own" selfmade Mobiflight to do this completly free and custom.

With Mobiflight your bind on the posibilitys of MF.... But sure.... Mobiflight can controll a Motor in case of a Offset ( For example the Offset that show us current Lever Position in Sim).
And you can readout things like AT ON ... Mayber also AT in HOLD (That not tested by myself) ..... Finaly you can controll a LED Output that is simply ON/OFF in case of your indication Offets ( Like ON if AT is active and OFF if not) ..... And this Output can use instead a LED also a Relais ...... Finaly this Relais can controll power of Servo or also the power of your glutch.

Summary.... A lot is possible but i think your not be able to build it 1:1 Real with Mobiflight. We pretty sure need to do some compromises.
Good Luck !
2020-05-07 14:50
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