JRK Setup and Pots Issues

[thaparser]

I'm using the JRKs and had issues with the shaking due to pots in the beginning.
I hope your pots are not multiturn, you should only use <360 turn pots (not sure what that is in plain English, I'm not native speaker).
anyhow, I had to use cheap and simple pots (I now run with 1 pot 5kohm and the other 10kohm - except the JRKs configuration, nothing else makes a difference).
I've noticed your feedback range is very short (131 positions). that's not much wiggle room for the pot.
back to the shaking: check your JRK software's report on actual feedback. if it varies too much while in stand-by then you may need to change the pots but first you need to be able to give it at least a few hundreds of range (mine is now using ~600 from min to max).

about the faulty JRK, first try to disconnect everything from it and see if it behaves better. there's one thing I'm struggling with now: USB power. it seems my PC doesn't output enough and one of my JRKs disconnects sometimes while in game and I need to reconnect. your motors are bigger and may drain more power. weirdly enough, the power is not drained always from the 30A power supply I use and if your USB port doesn't supply enough, your JRK may not work properly.
alternatively, you may have a faulty power cable/connection to the JRK and all power is drained from USB (it happened to me as well)

this was long, hope it helps.
cheers!

[Tombo]

Hi,
i'm not using jrks but had similar problems with jittering pot input. I searched aroud the internet and found that many people solderd a 100nF capacitor betwen ground and pot output. For me the pot signal was getting better with this solution. Maybe this helps you too.

Thomas

[prodigy]

Thanks for those solutions.

I used 5k cheap pots and didn't have those problems with JRKs.

What comes in my mind too, if someone is using wipers and they are not fully isolated, can this leaking current interrupt pots signal and make it jitter?

[thaparser]

regarding shaking, hopefully that's not due to oscillation from the PID settings for the motor.
for PID set-up, I've actually followed this simple approach: http://en.wikipedia.org/wiki/Ziegler%E2 ... ols_method
I'm currently using the first option: start with all values 0 (for P, I and D) and increase P (I used .5 increments); as soon as the motor starts to oscillate you've reached the value which you'll need to half in order to have a sufficiently good set-up P. for example: if while you increase your P value your motor starts to oscillate when P reached 4, then you'll need to set P to 2 and leave I and D to 0. this is the approach I'm using and it is lively and fun! =

hth, cheers!

[sirnoname]

The most importand setup is a good pot connection with 0 to 100% of the positions that the JRK can reach.
You can have a look to the Arduino X-PID post where I describe all the possible pot setups. (there is another thread for pots with more infos)

[Tech2123]

Have you solved the jittering? What did you end up doing, Im using the same setup almost exactly