Motorised TQ project

[masmaz]

Hi,
After 3 weeks of intensive work to motor a TQ I finally succeeded.
It's a topic that has been covered by many people but no one has ever published the solution, I don't know if because they didn't succeed or because they kept it to themselves.
I chose to share it.
The main problem was to install the 3 servomotors for the 2 throttles and the SPD BRK inside a FlightSimPM TQ, the second and most difficult step was to connect the servomotors with an Arduino Mega board and configure it with Mobiflight + Prosim738.
It was not easy because there was a problem of blocking the servo as soon as it was connected to the MEGA, so it was necessary to add two relays that through a configuration on Mobiflight as if it were a led and on Prosim as if it were a solenoid you have the disconnection of the servomotor from the 5v or from the signal, being able to move the throttle lever in manual mode.
below are the wiring and configuration diagrams.

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[masmaz]

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[Joe Lavery]

This looks very interesting, I've not long completed a new manual throttle, because I didn't have the knowledge to do what you have accomplished.
What size servos did you use and how did you connect them to your throttles... any pictures would be helpful.
My levers are simply connected via a large cog to a smaller cog attached to a pot.

regards
Joe.

[masmaz]

[masmaz]

This looks very interesting, I've not long completed a new manual throttle, because I didn't have the knowledge to do what you have accomplished.
What size servos did you use and how did you connect them to your throttles... any pictures would be helpful.
My levers are simply connected via a large cog to a smaller cog attached to a pot.

regards
Joe.

other images is trade secret ...  

[ame]

Technically the relays should be unnecessary. They are basically being used to disconnect the PWM signal from the servos.

I can see two other ways to do this. First, use a logic gate instead of the relay. The simplest would be an AND gate, where the inputs are the PWM signal and the other control signal.

The second option is to do it in software. When you want to drive the servo, turn the PWM signal on at the desired rate for the desired position. When you want the servo to be free, turn the PWM signal off (basically set the pin to zero). If this is not supported by the higher-level software it might be tricky, but it is just software, so it ought to be possible.

[masmaz]

consider that the Arduino board must account for Mobiflight + prosim738 ... if prosim cannot communicate with mobiflight arduino it does not give signs of life ... unfortunately I am not a programmer but together with those who have done mobiglight the best way has been that of the relays .. however, who is a programmer could study this page .. it would be interesting if you were able to eliminate the relays:

Introduction MobiFlight programmed

[Joe Lavery]

I believe that most users who have built their own throttles or converted real ones use slip clutches not relays when using manual mode. The pot still keeps track of the location of the lever, and the servos stay energised even if the pilot is overriding the A/T.   
Although in reality a real pilot would disconnect the A/T if he wanted to take control of the throttle.

I'm sure some of the more knowledgeable members here will clarify this point.

[KyleH]

...   
Although in reality a real pilot would disconnect the A/T if he wanted to take control of the throttle.
....

Not necessarily. Boeing throttles are designed with the clutches so that the pilot can stop the auto throttle from doing what its doing by just moving or holding the throttle handle for the desired result. This is done for momentary periods where you want just a brief interruption to what the auto throttle is doing before allowing it to return to normal operation. i.e. a level off that combined with a speed reduction, where the throttle may be acting too aggressively.

[navymustang]

You are both right - in a quick reaction scenario the pilot flying simply manually overrides the A/T, then when a moment is available disengages. Depends on what his other hand is doing 

When we take our 737 to shows like ITSEC in Orlando, it almost always comes back with a broken TQ because it is a Cockpit Sonic device with plastic gears and no slip clutch. And when those "real" pilots fly it, there is a constant desire to put hands on the throttles when the A/T is engaged.

Ah - the lovely difference between a $5,000 TQ versus a $10,000 TQ !

[Joe Lavery]

My old PPL instructor is now a commercial pilot who trained on 737s and he told me he would never fight against the AT, thats what the disengage button is for on the throttle handles. He said it takes simply seconds to re-engage when the operation is completed. But he agreed he's seen other pilots do it!

[masmaz]

hi
now i have a problem with the spoiler that despite being correctly, at least i think so, configured with the offsets that in theory are 3, in fact with SIOC they were both configured: 0x336 on ground, 0xBCC arm and 0xBD0 control, but despite the fact that once the wheels are on the ground, the spoilers of the aircraft are raised the lever does not want to move. i tried everything... even on prosim... 
any ideas?

[KyleH]

My old PPL instructor is now a commercial pilot who trained on 737s and he told me he would never fight against the AT, thats what the disengage button is for on the throttle handles. He said it takes simply seconds to re-engage when the operation is completed. But he agreed he's seen other pilots do it!

Your instructor is free to operate how he sees fit, and there are good reasons to disconnect depending on the circumstances, but there is no reason to be alarmed about others operating that way.

At the risk of sounding a bit like a my dad is bigger than your dad argument...
My mentor who showed me that technique was an experienced 767 captain, and 767, 787 and now 737 instructor. He was trained by Boeing and told me they are designed to be able to be used that way.

That said, our simulators are probably not built as robustly and would disengage the A/T before moving a motorized throttle handle.

[masmaz]

sorry but I don't need off-topic polemical posts I need posts that help me solve my problem ... other discussions open another post and kill yourself there, thanks

max

[Joe Lavery]

We would tell you but its a trade secret.

[Joe Lavery]

At the risk of sounding a bit like a my dad is bigger than your dad 
[/quote]

WELL....when I was speaking to Boeing yesterday...LOL 

[masmaz]

Spoiler configuration completed
max

[Flying_Fox]

It's a topic that has been covered by many people but no one has ever published the solution, I don't know if because they didn't succeed or because they kept it to themselves.

I posted the details of my TQ conversion quite some time ago:

https://elephantair737.blogspot.com/p/throttle_13.html

My unit in Autothrottle mode can be overridden manually without switching auto off. But this is a real 737-200 unit.

[ame]

consider that the Arduino board must account for Mobiflight + prosim738 ... if prosim cannot communicate with mobiflight arduino it does not give signs of life ... unfortunately I am not a programmer but together with those who have done mobiglight the best way has been that of the relays .. however, who is a programmer could study this page .. it would be interesting if you were able to eliminate the relays:

Introduction MobiFlight programmed

Ok. I looked at the MobiFlight source code for servos. It seems that the servo position is written constantly, so the servo will drive constantly, and will resist any external force. There is a piece of code that is commented out which would stop driving the servo when it reaches its final position. Which you don't want. Which is why it's commented out.

I looked at the MobiFlight tutorial for servos. To do what you want you would need an additional setting. The same control line that you use for the relay could be a software control to drive the servo or let it run freely. We could call it "Inhibit Servo Drive".

"Inhibit Servo Drive" would be the same signal that controls the relays (or any chosen signal), but there is no relay because it's done in software. If "Inhibit Servo Drive" is True then the servo drive pin on the Arduino will be switched off, and the servo can be pushed freely by external force. If "Inhibit Servo Drive" is False then the servo will be driven to the position set by its control variable.

If this functionality is desirable then you might submit a feature request and someone might implement it.