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Old 02-21-2018, 10:48 PM   #351
Thadiun Okona
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Quote:
Originally Posted by 98abaile View Post
If the gear ratios need to be increased so we can use a higher RPM, so be it, pulleys and belts are cheap. If I have to put up with a tiny amount of cogging that'll be damped somewhat by the backlash in the belts anyway, that's ok. I'm not saying you can't burn money if you want to, but consider the rest of us in your design. Because ultimately accepting some very minor flaws to get decent force feedback is far more reasonable than not having any force feedback because a very small number of people are happy to throw large sums of money chasing diminishing returns. Excessive amounts of money are what make it a non starter long before any minor inconveniences, so please consider the what is achievable to us with less money to spend in your design.

https://www.xsimulator.net/community...progress.7769/
If these guys can build better than commercial racing wheels with $35 motors there shouldn't be any reason why we can't do similar.

Interesting thread, but there are some reasons why the motors they use are unlikely to be up to this task. A FF steering wheel is a different animal that has 900-1080deg of travel, which makes motor selection much more forgiving. Using a 24:1 gear ratio, comparing total motor revolutions vs device travel the increased range of motion means it's roughly 19 to 23 times(!) less affected by magnetic cogging than a joystick application where your total travel is 30deg.

24:1 ratio @ +/-15deg = +/- 1 motor revolution
24:1 ratio @ +/-540deg = +/-22.5 motor revolutions
24:1 ratio @ +/-450deg = +/-18.75 motor revolutions

They ultimately settled on 12:1 ratio for that setup which would double negative cogging effects cited above but a 12" wheel is like a 6" stick in terms of moment arm. Conveniently for this conversation doubling the power to match a 12" stick would happen at 24:1 so the numbers stand in direct comparison. The thread was appreciated though and led me to Cousin Of Open Sim Wheel so now I'm eyeballing nice (used) big brushed dc motors with skewed armatures for a DD wheel. https://www.xsimulator.net/community...m-wheel.10915/

Even with expensive motors gear ratios can not be continually increased without running into penalties but I concede the exact numbers are not 100% certain. Those tradeoffs are likely why MS capped it at 24:1 instead of say 48:1 with motors half the power, but cost/complexity may have influenced this too.

With how good it works in practice, my guess is 24:1 is where the lines converged on the chart after experienced engineers applied calculus to optimize torque multiplication vs the penalties of the motor/system inertia. For this reason, I maintain this is a sensible place to start from. There are two advantages of higher ratios though, reduced motor cogging effects and increased torque. Designing around 24:1 runs the least risk of running into complications though.

Either way, FF sticks are sensitive to motor performance because the low rotation/limited range of motion poses challenges to the goal of smooth output with high torque, making suitable motors harder to find (generally more expensive) than less demanding use cases.
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Old 03-09-2018, 12:28 AM   #352
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Hi guys !

Just for information , for those who can afford that there is a new product on the market , ready to plug the warthog or the manngust , powerfull and swiiss made.. ..so certainly not cost effective but when you take account of the time we spend flying on our computer that could be a investment .

https://www.brunner-innovation.swiss...ls-e-joystick/

For the DIY project i maintain that as there is already an arduino code for a single axe racing wheel working "apparently very well" , taking two arduino micro and assign one axe on each of them separatly and you get your force feedback joystick (Ok the electronic parts i mean )

https://www.youtube.com/watch?v=v7A_fFHfN_c

I can tell you that because i have got two sidewinder ffb 2 and 1 force feedback wheel and i can assign each axe on two of theses device and i have force feedback on each devices ..

whrighting a code from scratch is a brave quest , why just use what is already existing and modifiy some of the code ( reduction of the potentiometer maximum course from 360 to 45 for exemple ) .

hope not to offend anybody but these are just some thoughts.
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Old 03-09-2018, 06:44 AM   #353
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I've read up on the CSL-E joystick, but like a bunch of other high-end force feedback devices, it doesn't use the DirectInput force feedback API, instead opting to use a special plugin with Prepar3D/X-Plane/MSFS. Unless a similar plugin is written for DCS, it won't work.
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Old 03-09-2018, 10:35 AM   #354
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@jpdesvals: so is that Arduino code able to control 2 axis simultaneous? Or is just for a steering wheel? I am ready to breakdown my warthog and adapt it to motors if the Arduino can control only the motors. However, this is not clear for me.
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Old 03-09-2018, 07:06 PM   #355
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Very nice hardware from Brummer... if I were in the market for plug-n-play or at least some leapfrog components to jumpstart making the stick I really want it would be a great option. 5Nm force in such a compact device is impressive! 3ph ac motors are way out of my league but definitely the way to go if you're going all-in and more importantly have interfacing to support it. Since I'm building a stick to replicate aircraft I've flown/have interest in flying, this rules out gimbals with x/y on the same (geometric) plane. Many if not most aircraft are coupled shorter in roll than in pitch by a few inches, which also complicates gimbals design because it either req the mechanism to take a lot of space (to route pushrods/cables) or one of the motors has to 'go for a ride' like the design settled on in this thread, which is the same design conclusion I came to in 2008 when I was first working on this (the sailplane sim it was being made for was already dated by then so I mothballed my project but its successor just released, Condor2).

This leaves me fabricating all the hardware, and since I'm on a very tight budget and also really don't want to reinvent the wheel, as I have mentioned before I am all about hacking MSFFII for practicality reasons. It has a decent ready-to-use interface and also there are known upgrade paths to achieve high quality FF, plus Condor2 devs have that stick and have tuned performances to it nicely so reinventing that wheel (which I have already done before) is well into the zone of diminishing returns.

The motors I settled on are not 'cheap' in the general sense even though they really are in relative terms (compared to other brands), but being popular means they can be found as surplus for a lot less money if you know what you're looking for. For the MSFF hack though, unfortunately the more commonly found 24v versions of those motors will not work, the terminal resistance is far too low so it will force the PWM into a 100% duty cycle at full current, so for the 14000 series motors they req different voltages at different sizes (there are 7 sizes in that series, my focus is mostly on 14204; good size/power) to achieve the proper resistance for the MSFFII circuit.

The 48v version of 14204 has terminal resistance is just about 4ohm, which is very close to ideal when calculating the voltage drop at full current (2.8a x 4ohm = 11.2v, where 12v is ideal). It's a 26oz/in motor (stalled torque), which at 24:1 ratio yields a mechanism with ~4.4Nm, very close in strength to the Brummer units which are 5Nm and will come out around the same size (or also work in the CAD design in this thread).

To this end I'm in talks with a motor manufacturer in China that claims to have perfect clones of those motors, down to the skewed armatures and identical performance but an order of magnitude less expensive than the Pittmans. Not sure how long it will take to get my hands on some to evaluate, but if they work for this it will provide a very reasonable pathway to functionality and it might make sense to do some group buys in the future for anyone that wants to follow.

Doing my homework on belts has led me to GT3 (successor to GT2), which is the current iteration of Gates's modified version of HTD rounded tooth pattern I was excited about in my last post. At 9mm width I don't think the 2mm pitch version are strong enough for this torque, but the 3mm pitch version is 4x stronger so likely the proper one but I'm going to get samples of both to evaluate the tactile implications as well as stretch/wear testing. If they feel like a zipper I'm going back to shaft-winding technique, either with wire rope or Spectra/Dyneema which is a lot less stretchy than steel and no more bleeding fingers!

@aburro, I wouldn't kill my Warthog yet if I were you but the answer to your question is no, you would need 2 arduino/steering wheel units, once for each axis but I have no idea how flight sims would react with that if at all. This gives me an idea to test my G29 as the 'rudder' in Condor2 though, which has FF commands presumably DirectInput API like the x/y, and I suppose might as well test in on the x/y too... if anything interesting comes of it I'll edit this post.
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Old 03-12-2018, 01:02 AM   #356
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I would like a fab joystick throttle and pedals that use hall sensors. But in the mean time I would like to add fab to my pft puma along with dampeners that I have plans that have peen tested for the collective and trim pedals the cyclic is still under development.
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Old 03-12-2018, 07:03 AM   #357
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Hi
for using two Arduinos:

we had this discusion twice already

FFB x/y is send as one set like :30% Force in direction 230°
a steerig weel needs only : 30% Force Positive

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Old 03-13-2018, 07:47 AM   #358
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Hi Thadiun,

I like your concept about building a solid solution based on the FFB electronics, however I would like to build a full scale control column with higher torque.

Would it be possible to connect even bigger motors with higher gear ratio to to the FFB2 electronics with some modding? I am still dreaming about 50Nm
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Old 03-14-2018, 01:46 AM   #359
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Quote:
Originally Posted by VO101_MMaister View Post
Hi Thadiun,

I like your concept about building a solid solution based on the FFB electronics, however I would like to build a full scale control column with higher torque.

Would it be possible to connect even bigger motors with higher gear ratio to to the FFB2 electronics with some modding? I am still dreaming about 50Nm

I'm building a full scale column with mine ...but for a sailplane cockpit (I'm sisu1a on the Condor forum) which in this case is 30cm in pitch/25 in roll, a good bit shorter than what you probably want plus my grip will be really light. The modified MSFF circuit will be running 2.8A vs the stock output of 0.7A; so @24v this is ~70w. While it might be possible to go crazy with the gear ratio, 24:1 is already two reductions (4:1+6:1). Going much beyond that may run into inertia problems but conveniently the way MSFFII circuit is designed it is based on stick position vs motor position, so it would be pretty straight forward test to since motor position is inconsequential.

The most powerful motors in the Pittman 14000 range that could be run at full torque with this exact need to be ~70w. The 14206 is 75w (36.5 oz/in, and the 48v version has the proper resistance) so I'll use that as a reference for the thinking. At 24:1, this yields ~5.75Nm. If you wanted to experiment with higher ratios though, a systematic way would be to plan for 24:1 but run that through a third reduction to see what you can get away with to see if you can get it up to the torque you want. If it works without unintended side effects... score ...but share the magic numbers!

For reference, by my estimates (lacking motor specs, I'm comparing to the closest motor from Pittman which is probably optimistic), the stock MSFF is <0.4Nm

There are also mods where people brute force two MSFFII's together, which would get you over 11Nm all things being equal. Man, I thought I wanted high forces... the glider I fly (SZD-59 Acro) ailerons really load up at higher speeds -set in concrete above 90kts, though most sailplanes have much lighter stick forces. I can see how warbird controls would req the crazy torque you want though.. mechanical linkages, big birds, high speeds, long levers etc. I was initially going for really high forces (and a full blown roll-your-own solution), but have scaled back my ambitions because perfect became the enemy of good :p

A luck would have it, I'm already waiting to hear back from Roland van Roy (the electrical engineer who cooked up that particular MSFFII mod) to see about running higher current with the same parts and asked if it's possible to run more current through it or possibly to beef it up further. It might just be a matter of bumping up the amp ratings of the MOSFETs and Shottkeys which are the most likely candidates to let the magic smoke out.
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Old 03-14-2018, 09:11 AM   #360
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With this Pittman motor that would mean a crazy around 1:200 gear ratio to land at 50Nm with a resulted output speed of 14RPM It doesn`t look good.
I would need a much larger motor to achieve this high torque, but then the FFB2 control board is the bottleneck.

I am a glider pilot in RL and I love Condor as well. Flying gliders in condor doesn`t require a very high torque indeed. But I would like to build a stick which can be cranked up for higher loads to fly warbirds as well.
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