Thrust assimetry compensation via LUA

[Muas]

Hi everyone.

The FSUIPC Sync Pos feature does well with throttle, pitch and mixture lever line up.

However, I tried a LUA approach to compensate thrust assimetry, and it works very well too.

Here's the code for twin engined aircraft - it easily can be adapted to four engined aircraft, and also for pitch and mixture.

-------------------------------------------------------
-- FSX Lua plug-in for thrust assimetry compensation --
-------------------------------------------------------

-- [[Thrust assimetry compensation for twin engine aircraft. In this method, assimetric thrust is compensated by adding half of the detected assimetry to each engine throttle.]] --


MaxAssimetry = 1024 -- maximum thrust assimetry allowed

while 1 do
    ipc.sleep(500) -- do nothing for half a second
    Throttle1Now = ipc.readSW(0x088C)
    Throttle2Now = ipc.readSW(0x0924)
    if math.abs(Throttle1Now - Throttle2Now) < MaxAssimetry then 
        -- there's an assimetric thrust, let's compensate
        MidValue = (Throttle1Now + Throttle2Now)/2
        ipc.writeSW(0x088C, MidValue)
        ipc.writeSW(0x0924, MidValue)
        -- done!
    end
end

-- by Muas, November 2009

The maximum assimetry value can be preset to taste.

Both throttle levers work well on their own; it's when they are pushed together that this plugin will get them lined up.

Compensated thrust is then set to the mid value between Throttle 1 and Throttle 2, unlike Sync Pos which line them up according to Throttle 1 value.

Save this file and name it Sync 2 Throttle.lua. Put it in the Modules folder, run FSX and assign a keybord key to run this file on the FSUIPC interface. Also assing a key to kill it. Then test it, and set the maximum allowed thrust values to taste.

Tests on the default FSX Boeing 737-800 showed excellent results.

Hope it might be usefull.

[Pete Dowson]

Hope it might be usefull.

Thanks! That's neat.

Can I add this to the Lua examples package? You'd get the credit -- if you can put your name in some comments at the beginning, perhpas?

Regards

Pete

[Muas]

Can I add this to the Lua examples package?

Sure you can.

I added the author credits.

[Pete Dowson]

Can I add this to the Lua examples package?

Sure you can.

I added the author credits.

Thanks!

Pete

[kizzle]

Hi,

Can you post the info for the 4 engine controls?

Can i use this with my PFC throttle quad? If so do i have to config it through Fsuipc to have this function work

Regards

[Muas]

Can you post the info for the 4 engine controls?

Can i use this with my PFC throttle quad? If so do i have to config it through Fsuipc to have this function work

Try this:

-------------------------------------------------------
-- FSX Lua plug-in for thrust assimetry compensation --
-------------------------------------------------------

-- [[Thrust assimetry compensation for 4 engine aircraft. In this method, assimetric thrust is compensated first on the outbord engines, then the inbord ones, and then the Left/Right couples.]] --


OuterMaxAssimetry = 1000 -- maximum outbord thrust assimetry allowed
InnerMaxAssimetry = 1000 -- maximum inbord thrust assimetry allowed
LeftMaxAssimetry = 1000  -- maximum left thrust assimetry allowed
RightMaxAssimetry = 1000 -- maximum right thrust assimetry allowed

while 1 do
    ipc.sleep(500) -- do nothing for half a second
    Throttle1Now = ipc.readSW(0x088C)
    Throttle4Now = ipc.readSW(0x0A54)
    if (Throttle1Now > 0) and (Throttle4Now > 0) then -- delete this line if reverse throttle compensation is required
        if math.abs(Throttle1Now - Throttle4Now) < OuterMaxAssimetry then 
            -- there's an outbord assimetric thrust, let's compensate
            OuterMidValue = (Throttle1Now + Throttle4Now)/2
            ipc.writeSW(0x088C, OuterMidValue)
            ipc.writeSW(0x0A54, OuterMidValue)
            -- done!
        end
    end -- delete this line if reverse throttle compensation is required
    Throttle2Now = ipc.readSW(0x0924)
    Throttle3Now = ipc.readSW(0x09BC)
    if (Throttle2Now > 0) and (Throttle3Now > 0) then -- delete this line if reverse throttle compensation is required
        if math.abs(Throttle2Now - Throttle3Now) < InnerMaxAssimetry then 
            -- there's an inbord assimetric thrust, let's compensate
            InnerMidValue = (Throttle2Now + Throttle3Now)/2
            ipc.writeSW(0x0924, InnerMidValue)
            ipc.writeSW(0x09BC, InnerMidValue)
            -- done!
        end
    end -- delete this line if reverse throttle compensation is required
    Throttle1Now = ipc.readSW(0x088C)
    Throttle2Now = ipc.readSW(0x0924)
    if (Throttle1Now > 0) and (Throttle2Now > 0) then -- delete this line if reverse throttle compensation is required
        if math.abs(Throttle1Now - Throttle2Now) < LeftMaxAssimetry then 
            -- there's assimetric thrust on left engines, let's compensate
            LeftMidValue = (Throttle1Now + Throttle2Now)/2
            ipc.writeSW(0x088C, LeftMidValue)
            ipc.writeSW(0x0924, LeftMidValue)
            -- done!
        end
    end -- delete this line if reverse throttle compensation is required
    Throttle4Now = ipc.readSW(0x0A54)
    Throttle3Now = ipc.readSW(0x09BC)
    if (Throttle4Now > 0) and (Throttle3Now > 0) then -- delete this line if reverse throttle compensation is required
        if math.abs(Throttle4Now - Throttle3Now) < RightMaxAssimetry then 
            -- there's assimetric thrust on right engines, let's compensate
            RightMidValue = (Throttle4Now + Throttle3Now)/2
            ipc.writeSW(0x0A54, RightMidValue)
            ipc.writeSW(0x09BC, RightMidValue)
            -- done!
        end
    end -- delete this line if reverse throttle compensation is required
end

-- by Muas, November 2009

Save this file and name it Sync 4 Throttle.lua.

Put it in the Modules folder, run FSX and assign a keybord key to run this file on the FSUIPC interface. Also assing a key to kill it.

Then test it, and set the maximum allowed thrust values to taste.

Tests on the default FSX Boeing 747-400 showed excellent results.

Please report back how it went.

[Pete Dowson]

Can i use this with my PFC throttle quad? If so do i have to config it through Fsuipc to have this function work

It doesn't matter how the throttle values get into FS, as the Lua program is working with FS's internal values, not your joystick or quadrant inputs.

Regards

Pete

[Muas]

Hi Pete.

I edited the 4 engine throttle syncro code, as it was not working as I expected.

Here's another working example for 2 engine throttle, prop pitch and mixture axxis sync.

--------------------------------------------------------------------------
-- FSX Lua plug-in for thrust, pitch and mixture assimetry compensation --
--------------------------------------------------------------------------

-- [[Thrust, prop pitch and mixture assimetry compensation for twin engine aircraft. In this method, compensation is achieved by adding half of the detected assimetry to each engine throttle, pitch or mixture values.]] --


MaxThrottleAssimetry = 1000  -- maximum thrust assimetry allowed
MaxPitchAssimetry = 1500     -- maximum prop pitch assimetry allowed
MaxMixtureAssimetry = 1000   -- maximum mixture assimetry allowed


while 1 do

    ipc.sleep(500) -- do nothing for half a second

    -- Throttle compensation
    Throttle1Now = ipc.readSW(0x088C)
    Throttle2Now = ipc.readSW(0x0924)
    if (Throttle1Now > 0) and (Throttle2Now > 0) then -- delete this line if reverse throttle compensation is required
        if math.abs(Throttle1Now - Throttle2Now) < MaxThrottleAssimetry then 
            -- there's an assimetric thrust, let's compensate
            MidThrottleValue = (Throttle1Now + Throttle2Now)/2
            ipc.writeSW(0x088C, MidThrottleValue)
            ipc.writeSW(0x0924, MidThrottleValue)
            -- done!
        end
    end -- delete this line if reverse throttle compensation is required 

    -- Prop pitch compensation    
    Pitch1Now = ipc.readSW(0x088E)
    Pitch2Now = ipc.readSW(0x0926)
    if (Pitch1Now > 0) and (Pitch2Now > 0) then -- delete this line if reverse pitch compensation is required
        if math.abs(Pitch1Now - Pitch2Now) < MaxPitchAssimetry then 
            -- there's an assimetric pitch, let's compensate
            MidPitchValue = (Pitch1Now + Pitch2Now)/2
            ipc.writeSW(0x088E, MidPitchValue)
            ipc.writeSW(0x0926, MidPitchValue)
            -- done!
        end
    end -- delete this line if reverse pitch compensation is required

    -- Mixture compensation    
    Mixture1Now = ipc.readSW(0x0890)
    Mixture2Now = ipc.readSW(0x0928)
    if math.abs(Mixture1Now - Mixture2Now) < MaxMixtureAssimetry then 
        -- there's an assimetric mixture, let's compensate
        MidMixtureValue = (Mixture1Now + Mixture2Now)/2
        ipc.writeSW(0x0890, MidMixtureValue)
        ipc.writeSW(0x0928, MidMixtureValue)
        -- done!
    end

end

-- by Muas, November 2009

Save this file and name it Sync Axis.lua.

It's worth assigning a keybord key to run this file on the FSUIPC interface, and another key kill it.

Set the maximum allowed thrust values to taste.

Tests on the FSX default Beechcraft Baron 58 showed excellent results.

[Pete Dowson]

I edited the 4 engine throttle syncro code, as it was not working as I expected.

Here's another working example for 2 engine throttle, prop pitch and mixture axxis sync.

Thanks!

I will be putting your excellent examples into the Lua package soon, when I do the next user updates.

Best Regards

Pete

[jimthomasjohnston]

Should the same code work in FS9? I can not get the twin engine code to work at all.

Jim

[Pete Dowson]

Should the same code work in FS9? I can not get the twin engine code to work at all.

The offsets are the same. It should work okay, but you may need a tighter loop -- FS9 might be overriding the values more often. Try lowering the Sleep value in the line:

ipc.sleep(500)

You should be okay with values as low as 20 or 50. Experiment.

Pete

[jimthomasjohnston]

Pete,

Just found the following line repeated several times in my FSUIPC log file:

52760 *** LUA Error: ...les (x86)\Microsoft Games\Flight Simulator 9\MODULES\Sync 2 Throttle.lua:1: unexpected symbol near 'ï'

Still can not get the plug-in to work. What does this error mean?

Jim

[hodge001]

Hi Maus

As I have only just acquired a set up that includes a four lever throttle, I have been using both your lua files in FSX, and I just wanted to say thank you for all the effort that you have put into this, and for sharing it with us.

Jim Hodkinson (no longer flying in circles)

[Pete Dowson]

52760 *** LUA Error: ...les (x86)\Microsoft Games\Flight Simulator 9\MODULES\Sync 2 Throttle.lua:1: unexpected symbol near 'ï'

Still can not get the plug-in to work. What does this error mean?

It means the Lua program has not compiled due to an error. If it doesn't compile it doesn't run. The Lua program concerned is Sync 2 Throttle.lua and the line is the first line, number 1 (the "1" after :). The error is "unexpected symbol near 'ï'". It sounds like you have either corrupted the file, or not selected it all and saved it as a whole, or have added your own non-lua characters to it.

Regards

Pete

[Muas]

As I have only just acquired a set up that includes a four lever throttle, I have been using both your lua files in FSX, and I just wanted to say thank you for all the effort that you have put into this, and for sharing it with us.

I made another update for the Sync 4 Throttle.lua file with the option to not syncronize the reversers.

In my 4 lever (Saitek) setup, the reversers are activated as key strokes at the end of the lever travel - the Saitek has buttons especially for that, so I set them to decrease throttle value when pressed (by repeting default F2 keystrokes) and cut it when released (default F3) - it works very good this way, but I found that when syncronized, the reverse levers tend to move slower than usual, so I de-sycronized the reversers by default in the code.

But there are people out there that uses half of the throttle lever travel to activate the reversers, so they might want to keep the throttles syncronized in negative values (reversed). If this is the case, one only needs to delete some marked lines in the code, and the 4 throttles will work syncronized during reverse operation too - as I said, on the above lua files Sync 4 Throttle.lua and Sync Axis.lua, the reverse sync option is disabled by default.