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Open Source Joystick FFB / DIY FFB Joystick


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I see. :D

 

That means you would be able to use off the shelf motors with reduction drive, for me the belts would give you some slight movement of the cyclic hmm joystick which mine has that allows fine input adjustment with out actually moving the physical stick position.

 

I'll explain that, currently my cyclic uses RC car dampers to hold it's position but I can put a small amount of force to provide a small amount of correction roll and/or pitch but the stick holds it position if I use a little more force then the stick position is moved with accompanying larger amount of correction.

 

This gives the cyclic a great feel.

Control is an illusion which usually shatters at the least expected moment.

Gazelle Mini-gun version is endorphins with rotors. See above.

 

Currently rolling with a Asus Z390 Prime, 9600K, 32GB RAM, SSD, 2080Ti and Windows 10Pro, Rift CV1. bu0836x and Scratch Built Pedals, Collective and Cyclic.

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After watching VR_FlightSim's video I came across this promotional video by Iris Dynamics describing a "contact-less" FFB system:

 

They also have a slightly more detailed video

.

 

While a neat idea I'm not completely sold on the concept itself. In particular I can't see how 5 magnets would be enough to give "hard-stops" as mentioned in the video. I appreciate that stepper and DC motors all work through magnetic forces but they have many more 'poles' or 'phases' (or whatever their called) that one could effectively set as a 'stop'. I just can't see how 5 magnets would provide enough resolution to give that fine level control, but perhaps I'm wrong. If it can be done with only 5 magnets that would be fantastic, but it sure would put a lot more onus on the programmer :D.

 

Anyway, it's a neat idea. Not sure if it would be applicable to what we're working on here but it sure is neat ;)

 

 

 

EDIT: BTW VR_FlightSim (and anyone else who cares), the way the YouTube tags on this forum seem to work is that you just need to place the video's serial number (that is the part in the address following the "v=...") between the [YOUTUBE] tags rather than the whole address. It took me a bit to work this out as well, but this seems to be how to do it ;)


Edited by Slartibartfast
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keep in mind, this is "short throw" stick design.

Anything like cyclic or "floor stick" is absolutely different story since u have much more room to hide your mech's..

 

How would a "floor stick" or cyclic be different?

I'm trying to build a floor stick/cyclic and I reckon this design looks great! What am I missing?

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After watching VR_FlightSim's video I came across this promotional video by Iris Dynamics describing a "contact-less" FFB system:

 

They also have a slightly more detailed video

.

 

While a neat idea I'm not completely sold on the concept itself. In particular I can't see how 5 magnets would be enough to give "hard-stops" as mentioned in the video. I appreciate that stepper and DC motors all work through magnetic forces but they have many more 'poles' or 'phases' (or whatever their called) that one could effectively set as a 'stop'. I just can't see how 5 magnets would provide enough resolution to give that fine level control, but perhaps I'm wrong. If it can be done with only 5 magnets that would be fantastic, but it sure would put a lot more onus on the programmer :D.

 

Anyway, it's a neat idea. Not sure if it would be applicable to what we're working on here but it sure is neat ;)

 

 

 

EDIT: BTW VR_FlightSim (and anyone else who cares), the way the YouTube tags on this forum seem to work is that you just need to place the video's serial number (that is the part in the address following the "v=...") between the [YOUTUBE] tags rather than the whole address. It took me a bit to work this out as well, but this seems to be how to do it ;)

 

I agree in that adequate centering force would require a lot of power.

 

Here’s some food for thought regarding magnetic FFB:

http://www.engineeringmatters.com/EngineeringMatters_Project_FFB.pdf

http://www.engineeringmatters.com/EngineeringMattersBrochure_joystick_techspec.pdf

 

This is a complex design, capable of 10 ft*lbs of force at 200W.

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Interesting.

I see they propose to use arrays of electromagnets in each axis rather than a single magnet which, to me at least, seems more viable:

MagneticJoystick_array.png

 

 

Interesting though it may be I didn't actually mean to subvert the thread with this discussion, so I'll let it go back to the actual project itself :thumbup:

 

But thanks for the incite, it is indeed most interesting.

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Hi

@Pinello

That is a Stepper Motor. (And a very Weakone too)

We had a discussion about what Motor touse some Pages Earlier.

If I recall it correctly we decided to usea Brushless DC Motor with a Gearbox.

Note: no worm gear.

@Slartibartfast

These Magnetic FFBs look interesting. But Ithink it is not very suitable for this OSFFB. If I understand it correctly theForces are distributed over the various electromagnets. And therefore we wouldnot be able to use different Setups. Not even different Coil designs as itwould affect the Magnetic field.

For the Gimbal itself. I made some testsand I think I have something useful.

It is basically a crossover for FlightsimVR's Design and the original SideWinder. I made a mistake in one of the Center piecesso it will take a few more days to replace it (I run out of Aluminum).

Next step will be the gear and Motor.

I tried the higher Voltage and it looks promising.

My test Motors are 12V DC and I am runningthem now on 24V DC

Most of the time they stay below the 12Vwith some Spikes up to 24V

But my Scope is not the Fastest so I cannottell for sure.

MetalGear_Honk

The threemost dangerous threads to Programmers:

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Hi

@Pinello

That is a Stepper Motor. (And a very Weakone too)

We had a discussion about what Motor touse some Pages Earlier.

 

If I recall it correctly we decided to usea Brushless DC Motor with a Gearbox.

Note: no worm gear.

 

 

Yes, sorry it was a stepper. But weak? 188W/peak current 28A/18 kgf.cm. Do you have a link to info for the motor you are using?

 

Regards

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Hey guys

 

@Slartibartfast

Thanks for the tip on the youtube videos. I couln'd figure it out and it was late night so I gave up and only posted the link. Fixed now;)

About "floor mounted" design. While the "cross" solution as seen in my video is working great in the simulation, it is also very technically demanding in the manufacturing process. Every single component needs to be "spot on" as there is 9 different joins working in conjunction with each other. To be honest, I would not attempt to recreate this mechanism without proper CNC equipment.

As I mentioned earlier this is great design for small spaces where minimum size boxing is required however building floor mounted stick give you a lot more options and space to utilize.

Therefore we can design (I will try next) much simpler FFB mechanism that can be build in everybody's workshop.. Bigger but Simpler:joystick:

BTW - did you get my reply on the programming subject?

 

@everybody

Forget about the magnets guys. It's not "home build" solution and it is not at all cheap as well.

Brushed or brushless DC motors are the way to go. Cheap, strong, easily accessible.

I've build plenty of test setups over the last two years. In order to get great force/torque on the stick, I would suggest two stages of transmission.

1st. Two cog gears (motor shaft + one)

2nd. Two belt pulleys (small one fixed to the +one)

 

This will provide great transmission ratio/force with minimum play on the stick. Also allowing for use of cheaper motors..

 

Jay

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Hi

I use far weaker Motors at the Moment. 93mNm.

but with some 21000rpm. Using a 10:1 Gear.

That is still not enough.

On top of that we will get a big Lever that will reduce our force.

 

 

As for my comment about the "weak" Motor. It is compared to otherSteppers.

Steppers have more Torque by design that DC Motors. So your comment abouttorque to Money Ratio is very valid. It has just not enough torque for the FFBdesign that I am working on.

 

 

MetalGear_Honk

The threemost dangerous threads to Programmers:

  • Fresh air
  • Bright sun light
  • The horrifying screams of singingbirds

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I can’t help with regards to motor choice. Backlash will always be existent with spur/straight cut gear mechanisms and any gearing system in some magnitude. Helical gears would be more ideal.

 

Another topic I haven’t seen discussed here is force sensing in addition to a force feedback. Without force sensing it will never be a proper closed loop system. Strain gauges are very cheap and a bridge can be placed almost anywhere on the Control stock and calibrated. Then programmatically the force being applied to the stick would always be known. This has the obvious benefit of detect hands on or off stick but also when interpolated with stick position can deliver a proper moment reaction force in a continuous loop.


Edited by SinusoidDelta
Brain fart about gears
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It is important to have a figure on the required max. torque at the grip of a floor mounted stick.

I think the 10kg (100N) at the pitch axis would be a good basis (however for realistic forces the stick should be able to deliver rather 20kg :))

 

The length of a floor mounted stick from the pivot to the griping point is about 500mm. So we need ca. 50Nm torque to get the required 10kg force.

 

Now this is quite a lot from a DC motor, so it has to be geared down heavily, but with the increasing gear ratio we are decreasing the max output RPM as well. At some point the output RPM will be too slow and the stick will lack responsivness and will be unable to deliver quick movements and adjustments. Another problem with the high gearing is the breaking effect. The motor will act as a break when you try to move the stick around under low force load conditions (at low speed or on the ground for example)

 

To avoid this we need a strong DC motor and the gearing should be limited. (I don`t have a value on the max. acceptable gear ratio, it should be tested)

 

EDIT:

Ok a bunch of things came to my mind about the topic:)

 

Every gear have some internal torque loss which is caused by friction. It is indicated by the efficiency number. The higher the better.

Therefore at the first stage I recommend to use planet gears. They are compact and efficient. (and expensive). The low backlash is crucial as well because the second stage (belt, cable, whatever) gear will amplify the first`s backlash. So if you have a 1:10 second stage it will amplify the backlash 10x!

 

What voltage motor should I look at? Is there any limitation of the current?

Here is a nice one:

http://www.ebay.co.uk/itm/Brushless-DC-Motor-UK-Seller-/381731796828?hash=item58e0fcf75c:g:S3UAAOSwG-1WvJ3i

 

 

 

.... exciting:)


Edited by VO101_MMaister

[sIGPIC][/sIGPIC]



KG13 Control Grip Building

Control Stick and Rudder Design



 

i7 8700K, Asus Z370-E, 1080 Ti, 32Gb RAM, EVO960 500Gb, Oculus CV1

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The low backlash is crucial as well because the second stage (belt, cable, whatever) gear will amplify the first`s backlash. So if you have a 1:10 second stage it will amplify the backlash 10x!

 

 

Hey

I can not agree with you. The second stage (belt) will reduce the backlash of the first stage (spur).

For example we will have 1 degree rotational backlash on the second gear of the first stage.

When we run belt from here (20 teeth pulley) onto second, final pulley (100 teeth), the backlash will reduce 5x resulting in 1/5 of a degree.

Just an example though

 

In conclusion, it's better to keep higher transmission ratio on the second stage..

 

Jay


Edited by VR FlightSim
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It is important to have a figure on the required max. torque at the grip of a floor mounted stick.

I think the 10kg (100N) at the pitch axis would be a good basis (however for realistic forces the stick should be able to deliver rather 20kg :))

 

10kg at the stick is probably a good target. Not too weak but a challenge at the same time:)

Do you guys suggest we have the same max. force (10kgf) on both, pitch and roll?

Or is one of them always bigger than the other?

 

Jay

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Hey

I can not agree with you. The second stage (belt) will reduce the backlash of the first stage (spur).

For example we will have 1 degree rotational backlash on the second gear of the first stage.

When we run belt from here (20 teeth pulley) onto second, final pulley (100 teeth), the backlash will reduce 5x resulting in 1/5 of a degree.

Just an example though

 

In conclusion, it's better to keep higher transmission ratio on the second stage..

 

Jay

 

You are entirely right :thumbup:

 

regarding pitch/roll force:

Becasue the human arm is much stronger back and forth than sideways the aircraft designers tend to use the load relation 2/1 at pitch/roll to achive harmonical control load. If we have 10kg on pitch then we need about 5kg on roll.

[sIGPIC][/sIGPIC]



KG13 Control Grip Building

Control Stick and Rudder Design



 

i7 8700K, Asus Z370-E, 1080 Ti, 32Gb RAM, EVO960 500Gb, Oculus CV1

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Briliant, thanks VO101_MMaister

 

One more question though. I'm currently drawing the mechanism and it occurred to me that 30 degree motion range (as on the small stick) is probably way too much for 500mm long shaft..

Any suggestions on the travel range on top of the stick?

 

Jay

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