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G940 - Force Feedback - discussion


fred41

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Hi Deathmechanic,

 

Here's a screenshot of the settings that give a nice progressive spring. I'm using a higher force (16) than Fred recommends (12) because I've lengthened my stick grip, so I will be losing some discrimination around the edges of the stick movement.

 

o7PjRG1.png

 

The problem I had previously was twofold, I was reducing the spring effects strength in Logitech Device Options (which prevents the stick giving it's full force) and had confused the Spring Force and Spring Saturation settings in SimFFB. So if you use the settings above as a starting point, and then tweak to your preference then it should be easy :thumbup:

Do you use VR? Do you feel sad when you are just a dismbodied set of eyes floating in the cockpit? Check out my list of paid aircraft modules that support the visible virtual pilot body:

 

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... yeah, thank you. Maybe it is time to merge 'ffb_experimental' back to 'master'.

 

I think this 15g additional weight in your stick may explain the oscillation you observed, since i really can't reproduce this behavoir here.

Theoretical i could reduce the minimal voltage (pwm) further, but this would increase the 'center play' too.

If you open your device next time, you could apply a grease with higher viscosity for x axis slide bearings.

This would damp the stick and stop the oszillations.

 

I have same issue but I don't have any magnets inside stick or other modifications.

But I am using master branch, not experimental one.

- Ну-с, так... - сказал хорошо поставленный мужской голос, - В некотором было царстве, в некотором государстве жил-был царь, по имени... мнэ-э... ну, в конце концов, неважно. Скажем, мнэ-э... Полуэкт... У него было три сына-царевича. Первый... мнэ-э-э... Третий был дурак, а вот первый?.. (с)АБС.

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'master' and 'ffb_experimental' branch are identical currently and i am assuming you are using the latest version of my patch.

 

My ffb 'center play' related modification, is based on an increased 'minimal voltage' for the dc motors.

The minimal voltage is essential to get an acceptable 'center play' window, because any dc motor doesn't start to output a torque, before all the inner friction forces are compensated.

Hence, an optimal voltage, will result in the smallest possible "center play" window.

 

 

Now the problem is: each device is different, because of aging, modifications, etc.

Unfortunatelly, there is now easy way for me, to export this parameter (minimal voltage) to the user.

 

So i finally implemented a value, that is basically a compromise. For me this value works perfect, because i did some simple, but very usefull modifications.

 

  1. fixed the two (roll) ball bearings on their axis (this axis is produced with a diameter to small)
  2. moved the motors closer to the cog-segments to eleminate the play within the cog's
  3. replaced the grease for all slide bearings with a higher viscosity grease

I would recomment to adapt your device accordingly, because you will get an very precise device this way and the oscillations will stop.


Edited by fred41
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  • 4 weeks later...

Hello Fred. Thank you very much for all the effort you have put into this. The community is fortunate folks like you are around!

I however am neither a software or mechanical engineer; just an operator. :( Could you please be more specific on how to accomplish the bearing and motor mods or Point me to where I can find the details?

Thanks again for using your skills to help out us die hard FFB users!:)

Respectfully.

Don

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Same here - what do you mean by clogs?

I doubt that there are dutch wooden shoes installed inside my g940 ;-)

Windows 11 Pro, ASRock Z390 Pro4, i5-9600KF, 32 GB G.Skill DDR4 3200, RX6900XT, TIR 4,TM Warthog Throttle and Stick, TM Pendular Rudders, Elgato Stream Deck XL

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Hi Wrap, hi Faustus,

 

sorry for my poor english, i better should have use a dictionary, as usual :book:

 

I actually meant cog (or cogwheel).

 

If i find the time, i will add some pictures/drawings to explain this simple modifications, since a picture still tells more then thousand (wrong english) words :music_whistling:

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  • 2 weeks later...

... i added 3 pictures, from the ffb-axis "gears" to the first page ...

 

I hope this pictures help to understand, what i meant with 'cogs' and

how the motors have to be adjusted to be a little bit closer to the plastic cog-segment axis.

 

Close enough to eleminate the play, but relaxed, to avoid higher forces.

After adjusting and fixing the motors with the two screws, the motors can be additional fixed with some soft glue (see third picture).

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@fred41

 

Big ThankYou! Fantastic job on the firmware fix, the stick feels like a new one again after 10 years!

i9 13900K @5.5GHz, Z790 Gigabyte Aorus Master, RTX4090 Waterforce, 64 GB DDR5 @5600, Pico 4, HOTAS & Rudder: all Virpil with Rhino FFB base made by VPforce, DCS: all modules

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... i added 3 pictures, from the ffb-axis "gears" to the first page ...

 

I hope this pictures help to understand, what i meant with 'cogs' and

how the motors have to be adjusted to be a little bit closer to the plastic cog-segment axis.

 

Close enough to eleminate the play, but relaxed, to avoid higher forces.

After adjusting and fixing the motors with the two screws, the motors can be additional fixed with some soft glue (see third picture).

 

Thanks a lot again - now I know what You meant..

I will try that when I can find the time and report back!

S!

Windows 11 Pro, ASRock Z390 Pro4, i5-9600KF, 32 GB G.Skill DDR4 3200, RX6900XT, TIR 4,TM Warthog Throttle and Stick, TM Pendular Rudders, Elgato Stream Deck XL

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  • 2 weeks later...
'master' and 'ffb_experimental' branch are identical currently and i am assuming you are using the latest version of my patch.

 

My ffb 'center play' related modification, is based on an increased 'minimal voltage' for the dc motors.

The minimal voltage is essential to get an acceptable 'center play' window, because any dc motor doesn't start to output a torque, before all the inner friction forces are compensated.

Hence, an optimal voltage, will result in the smallest possible "center play" window.

 

 

Now the problem is: each device is different, because of aging, modifications, etc.

Unfortunatelly, there is now easy way for me, to export this parameter (minimal voltage) to the user.

 

So i finally implemented a value, that is basically a compromise. For me this value works perfect, because i did some simple, but very usefull modifications.

 

  1. fixed the two (roll) ball bearings on their axis (this axis is produced with a diameter to small)
  2. moved the motors closer to the cog-segments to eleminate the play within the cog's
  3. replaced the grease for all slide bearings with a higher viscosity grease

I would recomment to adapt your device accordingly, because you will get an very precise device this way and the oscillations will stop.

 

Damping grease on the gearing may help also. I think it will be easy now to make a new better version of the gimbal itself with files already made - like Alec found above. The shaft itself can be made of aluminum. Only need someone who is interested enough to do so now that most people have access to shops with the necessary tools in major North American cities, certainly Europe as well.

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I'm currently planning a Frankenstick-G940 mod, combining the base with a Virpil MongoosT grip. I hope i can get some electronic parts from Virpil, will see...

i9 13900K @5.5GHz, Z790 Gigabyte Aorus Master, RTX4090 Waterforce, 64 GB DDR5 @5600, Pico 4, HOTAS & Rudder: all Virpil with Rhino FFB base made by VPforce, DCS: all modules

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Now that the patent is up, I’m sure a lot of people would ay for a G940 V2, including me. My sidewinder has so few buttons...

 

My dream since owning G940 for years, and then moving through CH, Thrustmaster etc to VKB, is that VKB would make a FF base and FF pedals by using magnets.

 

I would as well see the G960 from Logitech that doesn't change much, like add a two 8-way hats on stick, a 4-way + push to grip and maybe an extension. And then fix the FF effects problems etc.

 

Nothing else really for a so nice kit. Oh, and change the cable heads to something compatible and easy to attach/remove.

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Great work fred41. Thanks for your efforts!

 

I think it will be easy now to make a new better version of the gimbal itself with files already made - like Alec found above. The shaft itself can be made of aluminum. Only need someone who is interested enough to do so now that most people have access to shops with the necessary tools in major North American cities, certainly Europe as well.

 

 

I had already started on some designs to fix this gimbal. I have a CNC machine shop and a good 3D printer (not a hobby printer). So making and testing the parts (machined, or printed) isn't a problem.

 

I started working on this a while ago and fred41's firmware fixes has reinvigorated me to finish the task. Part of the slop on this stick is because of the software deadzone, or I call it the weakzone because the motors just stop trying at the stick's center position. So making a new gimbal was a waste of time if the software still didn't take up the slack, literally. But it looks like fred41's changes have done that. So now making a new tighter gimbal is finally worth it. Time to dust off the Solidworks models and see what I can come up with.

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Great work fred41. Thanks for your efforts!

 

 

 

 

I had already started on some designs to fix this gimbal. I have a CNC machine shop and a good 3D printer (not a hobby printer). So making and testing the parts (machined, or printed) isn't a problem.

 

I started working on this a while ago and fred41's firmware fixes has reinvigorated me to finish the task. Part of the slop on this stick is because of the software deadzone, or I call it the weakzone because the motors just stop trying at the stick's center position. So making a new gimbal was a waste of time if the software still didn't take up the slack, literally. But it looks like fred41's changes have done that. So now making a new tighter gimbal is finally worth it. Time to dust off the Solidworks models and see what I can come up with.

Agreed. The stick is already feels worlds better with the new firmware. Any further improvements can be made mechanically. It's been a long time since I've used the stick, but I believe the hall sensor can be calibrated as well in the software so any new design should be good to go.

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I came up with 5 simple changes anyone can make to the stick (which includes one 3D printed part) which make a good improvement mechanically - takes out all the slack or backlash. I'll post a video of the changes soon, including the model of the 3D part for people to print their own, and I'll post it on Shapeways for people without access to a 3D printer. Other than the 3D printed part, getting some proper grease, and buying some Locktight if you don't already have some, everything can be done at home with a screwdriver and a file. Sorry for the teaser - give me a couple days to get the video done because doing the changes incorrectly could make things worse or ruin your G940.

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... thanks for any friendly feedback, all.

 

@Drakoz, thank you for linking this thread and my patch repository.

Your announcements, regarding the improvement video, are very welcome and i think many G940 users are waiting exactly for some help of this kind.

 

@aeliusg, the hall sensor itself (MLX90333) in the G940 is very well calibrated/programmed. But yes, the calculation of all the forces and especially the spring/damper forces is done in the firmware, so there is some potential to adapt FFB behavoir.

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Maybe interesting for all G940 owners, after sticking 10 years with the complete G940 bundle i recently switched to a Virpil T-50CM throttle. The most interesting thing i felt was how the stick's behaviour "changed" with the original throttle dísconnected. It feels much more precise now, it's hard to describe it. It seems that the original throttle introduced "disruptive" data while being used, degrading the performance of the stick (and yes, i had the spiking problems...). Without the original throttle connected, it feels so much smoother and precise.

i9 13900K @5.5GHz, Z790 Gigabyte Aorus Master, RTX4090 Waterforce, 64 GB DDR5 @5600, Pico 4, HOTAS & Rudder: all Virpil with Rhino FFB base made by VPforce, DCS: all modules

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Thank you Fred for all your efforts! I just updated the firmwares all the way up including your patch. I am getting a precision out of the stick now that just was not possible before.

 

I ran into a very weird thing though. Currently (I have not yet rebooted), the stick appears to be stuck in some kind of 'demo mode'. I can use the stick itself fine in DCS at the moment, axis work great and never so smooth. But the buttons on the stick, almost all currently initiate some kind of severe force-feedback effect. Each button seems to do something else. Its almost as if my stick is now in 'display mode' or something you would find if you were to demo force-feedback in a store display.

 

I have done a few quick googles and cant find anything about this mode. I will reboot soon, see if that clears it. Just wondering if anyone had seen this behavior before.

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... the stick appears to be stuck in some kind of 'demo mode'....the buttons on the stick, almost all currently initiate some kind of severe force-feedback effect. Each button seems to do something else. Its almost as if my stick is now in 'display mode' or something you would find if you were to demo force-feedback in a store display.

 

You must have the Logitech G940 Game Controller control panel open in the background (this is through the Windows Game Controller screen). So yes, it is demonstrating it's demo mode which is the result of running this control panel. I'm sure by now you have rebooted and it isn't happening anymore because the control panel doesn't reload on a restart.

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You must have the Logitech G940 Game Controller control panel open in the background (this is through the Windows Game Controller screen). So yes, it is demonstrating it's demo mode which is the result of running this control panel. I'm sure by now you have rebooted and it isn't happening anymore because the control panel doesn't reload on a restart.

 

Ah cool, must have been that. It went away after I briefly removed power from the unit.

 

One of the benefits of updating all the firmwares is that I was able to significantly reduce the deadzone, so I can be far more precise with sight inputs. But I am having to learn how to fly all over again, so that's interesting :p

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