Another Playseat 2DoF -> 3DoF

I've been reading a lot in the forums and scavenging parts for a while.
Finally I have started building the SIM.
A little background to "stand out from the crowd"

I am competing in the Norwegian Drift League in the Semi-Pro drift class.
I drive a Opel/Vauxhall Calibra that originally is an FWD/4x4 car that I have converted to RWD, tuned and licensed. 410 BHP @ wheels, which is enough power to break loose 225/45/17 tires at 100km/h.
When I feel like doing lap times I smack on some semi-slicks.

My racing "career" started the usual way, by doing some trackdays with my daily driver (the same car, just as 4x4) and ice racing and escalated from there.


I've always wanted a racing SIM. I've "always" had a steering wheel, got my first way back in the days when Pentium 90mhz and Need for Speed was the hottest you could get. Later I bought my Playseat and have been enjoying it for some years now.
But I've always been missing the early signs of when you loose grip and start to skid. Especially after I started drifting this became a must.
That, together with the news that Rudskogen (a popular race track in Norway) was under development for Assetto Corsa kickstarted my sim process. (picture 1, 3 and 4 is from Rudskogen)

NOW, to the part that is interesting for this forum.
I will build a 2DoF first, and later convert it to 3DoF
The motors will connect to the front and not up high on the back of the seat. (space issues in the room)

My parts list:
3 x JRK's (1 spare / for the 3Dof)
2x Motion Control UK 80rpm 60:1 worm gear motors 12V 23A
2x HP DPS-600PB 12v 47A PSU (connected in parallel with load balancing)
1x Playseat w/Logitech G25
1x hydraulic handbrake w/pressure switch

I've started the build, and used some leftover parts from my drift car.

Pictures says it all basicly...

I have converted my old hydraulic handbrake to be modded on the sim, by using a pressure switch from a motorcycle that will be soldered into one of the buttons on my G25.

Then over to the current questions:

Should the motors be positioned any specific distance from the pivot point?
Should they be at a 45 degree angle to allow for the same movement in all directions?

More questions will certainly rise, but at this stage I think that is what I am currently uncertain about.

Something happened with my pictures, the last ones did not get inserted into the post...
Guess it doesnt really matter...

Anyhow, this is how the hydraulic brake looks now, I might mod it a little more to allow for some more feel, right now there is nothing to "flex" so it feels like a "button" , no feel, just on / off.
I might add a lenght off copper tubing and leave some air in the tube (not bleed it) to allow for some compression of the air to take place before it reaches the pressure that is needed to activate the switch.

Forgot to mention that I plan on using the Oculus Rift, that is why I did not mention any screens and weight of those.
The original plan was to use a 24" monitor, but now I cannot wait for the Oculus to be released, love the tought of being able to look out of the side windows while going sideways.
Needless to say, my sim is going to be a part of my training devices

Thank you for your quick reply.
I am terrible at drawing and do not have a 3d program...
But as I'm almost done building the frame and motor setups, I can take pictures after tonights build

The quick and dirty description is that I will use the frame already built

The shaft joint is at the balance point with the playseat on top.
The motors will be in the front, and am planning on welding a bar to get the connecting points higher up, approximately at the height of where the knees are, that should be pretty close to the center of mass/roll point.

I might modify later so that the shaft joint get closer to the bottom of the seat, the way the Playseat will sit on top off this frame gives about 20cm between the joint and the bottom of the seat. But I will try this first.

I will keep that in mind (regarding the Oculus Rift's) and build it for small, quick movements. I will make a lever with multiple holes so that I can easily change from 40-60 mm.

Regarding the height of where one connects the motors, does it play a big role if they are mounted below the roll center?
Like this:


instead of higher up like this:

It took a little longer than expected to fabricate these parts
So I didnt manage to finalize construction yesterday, but pretty close now. Hopefully I will be done with the building tonight and can start to install the electronics.
I welded the strut to move the connecting point higher

Then I drilled and tapped the rear of the motor shaft to M6 (for the pots) and built the connector shafts.
I drilled holes at 40, 60, 80 and 100mm ctc to allow for testing. When I first drilled the 40mm ctc I felt that would not create enough movement, but guess I'll see when I fire it up.

The tap in the motor shaft for the pots did not become 100% centered, so I am afraid that might give me some problems down the road. To connect the pots to the bolt I am planning on just using heat shrink tubing, that should be stiff enough to not flex much, but pick up the minor variations that might occour..

The time limit on editing posts is a little annoying - is it just because my user is so new, or is it locked for everyone after 1 minute?

Anyhow - I will be using cheap pot's , but was think about changing to Hall effect pots. I know the 6127V1A180L.5FS is good, but I cannot find them on ebay.
Does anyone know of a good pot for our JRK's that is available on ebay? ....

Higher up, "foot motor" style at least. Better for overall leverage. You will get better performance from motors connecting higher up.
I take it you understand performance, right?

Newark should have something for you.

http://no.farnell.com/

Performance I understand
The connecting points are now aprox. 30 cm from the bottom of the chair, hopefully pretty close to the roll center.

To mount my pots I welded together som M6 bits'n'pieces, pictures says more than a thousand words. Alot of adjustment possibilities

The lever I welded from a tube with ID of 16mm, so had to split it up, but it is solid now:


That was as far as I got last night because all of the sudden one of my switches decided to stop working and my internet died, which is not so good as I got a "smart house", and with no internet, no lights

Very Interesting idea for the pot mount. Good job Bud. One thing i noticed tho. the lever's themselves look to be on the thinner side for material thickness. I would keep an eye on those for flex in the initial testing.

I think you are correct regarding the material thickness on the lever's... they did flex a little when I took my monkey wrench (plumbers grip, dunno the english name for it) and twisted them... So I will probably have to reinforce them. But that is a minor problem

Got the engines mounted and transported the beast home. Engines are mounted with M10 bolts into the steel frame under the bottom plate, so should not be any flex problems. Will change the flimsy M10 connectors with uniball's (rod ends) as soon as they arrive.
Next up is wiring the electronics. Then hopefully get the thing to move

For sheer referance, For MY setup on how i have my motor's bolted down, The thin angle was able to be twisted under motion, The Thick Angle....Lol not so much.

Wow, is it that much force in action?
Guess I'll upgrade the mounting brackets as well
the load spread is no problem, as the M10 bolt goes through the mounting brackets, through the wooden frame and through the steel frame below the wooden frame, so the wooden frame is just for looks
But I will most certainly improve the things you guys are pointing out

Got the JRK's running, updated firmware so that all 3 is running 1.4
Configured the pots and feedback looks good.
But when I drag the slider back and forth quickly in the JRK configuration utility, the motors sometimes "stutter" and freezes in one direction. also makes a sound almost like the sound you get if you connect AC to a DC motor (trying to move back and forth really fast).
I've followed eaorobbie's guide: http://www.xsimulator.net/community/threads/playseat-to-2-dofseat.5401/page-2#post-56352

If I change the max duty cycle value to 200 (max is 600) I only managed to provoke this behavior once, while at 300 and above it is easy to provoke this behavior. Limiting max current to 10amp also worked, but both of these "fixes" resulted in slow movement.
There should be plenty of power available as I use 2 x HP DPS-600PB 47A in parallel with current share/balancing and the test is with no load on the motor. (maybe that is the reason, not enough resistance on the motor?)

In case of issues with the power I can put in a 1 fahrad 12v condensator left over from my car stereo, that should definitely fix any supply issues.
So for now I'll just go ahead with the build and installing simtools, maybe this behavior is only in the JRK utility and not in real life with weight on the motor levers.

Thanks!
Downloaded and looked at bsft's JRK guide.
Started working with the values, but already at 0.1 P I managed to provoke the stuttering/twitching. Error 0x0004 Motor driver error occur at the same time as the stuttering.
Same goes for both motor's / JRK's....
I'm thinking that either the cheap pot's are to blame, or the power supply's.
Didnt have time for much trouble shooting yesterday so will continue today by measuring voltage drop, a new pot, and so forth.

My JRK settings, including the error page: