Question First build no joy

Greetings.
I have built my first rig and it is horrible.
There is no smooth motion no matter what I try. Every motion is stepped / jerks.
If I slow things down the jerks are just slower.
It is like the motors move only in steps.
I have spent many hours and tried following the tutorials but nothing seems to stop the stepped/jerky movements.

Equipment rundown..
Software: Simtools 2.3 Diy w/paid license.
SMC3 packet serial beta8 softstart on a Arduino Uno.
Pcars2

Hardware :2 dof rear mounted wheel chair motors 160 rpm /24vdc.
Pushrods are 10mm threaded rod with ball ends and are attached to shoulder height on the chair.
2x32 sabertooth driver.
2 12vdc car batteries in series for 24v
I7 7700 windows10 overclocked to 5ghz
arduio Uno/ smc3

Hall effect potentiometers (180deg) from Digi-key

I know the wheelchair motors have 3-5 degrees of backlash in them and I have taken them apart. There was no aparent way to reduce this as it is machined into the gear mounts.

Thanks.
tom p

what potentiometers are you using ?

what happens when you run the smc3 test program - do you get smooth motion ?

if you put a capacitor across the potentometer does it settle down

Arduino Due is not supported. Only Uno and Mega.

Yes that was a brain typo on the arduino's. I am using the Uno.
The pots are hall effect 180deg from digikey.
I put some .47mfd across the pots and wipers and there is no difference.
When I run the SM3 utility software , it is pretty smooth.
I am testing with the sine wave output. Once in a while I will get a glitch as seen in the yellow graph line representing the PWM out.
I can feel some microsteps in the sine curve as it is running.
If I manually move from one end to the other end the rig moves smoothly and rather quickly to the opposite end of travel. There it abruptly stops!
I assume I am suppose to be sitting in the rig when all this is going on.
I ran the TUNE in motor manager and saved the settings.
No real difference. Just shakes the crap out of me when driving.
I am more than willing to try about anything to get this going.

Here are the screen shots.. I am still learning this forum. It operates a bit different than what I am used to.
Also I appreciate your help very much...

Thanks for looking at my settings.
I did make progress today.. The problem was my Kp setting was way too high.
It was set around 400. Reducing it to 75 got rid of most of the bazaar jerking.
I am on the track to getting the rig playing correctly.

Shout out to MarkusB.

That makes since because your motors run 2 to 3 times faster than most people use.

Getting closer and closer to dialing it in. It seems like I have a lot more pitch going up hills than down. Not sure what that is about. I seem to notice that the gear box surge varies a lot. I have yet to add any heave. I do not know if it adds anything to the motion when dealing with a simple 2 DOF rig...
That said... I am finally having fun !!!

Hi Tom,

a pure 2DOF simulator can only perform pitch and roll movements, while the surge, sway, and heave forces need to be mapped onto these two:

• surge is emulated with the pitch axis: acceleration = positive pitch angle / braking = negative pitch angle
• sway is emulated with the roll axis, but usually in the opposite direction. Example: When you are driving in an inclined left curve, the car tilts to the left, but the sway force presses your body to the right.
• heave is emulated with the pitch axis, but probably with rather small amplitude compared with pitch and surge.

The problem with this kind of emulation is that the surge/sway g-forces tend to eliminate the pitch/roll angles and vice versa.

Example:
You are driving downhill, causing your car to accelerate. Acceleration increases the pitch angle, while at the same time going downhill reduces the pitch angle. Depending on whether pitch or surge causes the larger motor movement (depending on your axis setting), your seat moves forward or backward. This can lead to quite confusing sensations.

This may also be the explanation for what you described in this sentence: "It seems like I have a lot more pitch going up hills than down."

An approach for solving this problem for a 2DOF simulator is to add a g-seat. You will find multiple builds in this forum (including my own, for which I will hopefully post an update this weekend).
Basically a g-seat consists of 1 or 2 sets of paddles that apply pressure to parts of your body.
For example, surge and sway are simulated with backrest paddles that push against your back. For surge, both paddles apply pressure, and for sway just one.

The forum member @SeatTime has gone a step further and developed a "g-system" that pulls your upper body forth, back, and sideways with bowden cables.

Hope this helps.

Best regards,
Markus

Like I have said before a bright light shines so clearly.
That explanation really helped.

I have been studying your G-Seat with great enthusiasm.
Impressive.........
Adapting it to the gaming seat I am using is not going to be easy.
But it's on the list....

I am anxious to try out my VR headset next.
I have had a Rift for about a year but just got the Samsung Odyssey a few weeks ago. The resolution in the Samsung is much improved over the Rift and appears the contrast ratio is greater.
I fly a lot of R/C aircraft and have a software sim called Real Flight 8.
With that particular program the Samsung Odyssey greatly out performs the Rift .
Hopefully the tracking system on the Odyssey will be ok with the 2DOF chair.

.
Many thanks,
Tom..