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Hello, please help with jittery motors

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Haydn, Apr 20, 2020.

  1. Haydn

    Haydn New Member Gold Contributor

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    yeh, as you say, both computers have the same config settings. i did have the utilities connected in the beginning no problems but had a problem connecting to simtools, so i updated the driver and think that may be when the problem started, not sure though. i reverted the driver back to the prior installation, but that didnt fix it. im at a total loss as to how everything works fine on the laptop (not even any warmth in that wire) and it fries instantly when connected to the PC. i can connect to PC as long as power supply isnt on.
  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    That sounds like a significant PC usb related issue, but I can't conceive how that would occur.
  3. Pit

    Pit - - - - - - - - - - - - - - - - Gold Contributor

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    Please do not understand my comment as an affront, but IMHO I would "never" do the same mistake twice or even more often. As you noticed your PC shows usb issues in "frying" your ground wire of the Arduino. You are going to risk a hardware failure only by doing it again and again ;)

    I guess since your notebook works fine try fiddling out the source of the short circuit of your PC before you take the next steps. :thumbs
  4. Haydn

    Haydn New Member Gold Contributor

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    Thank you both for your response,
    Thanks for your reply, and yeh! i get where your coming from in not trying the same thing over and over again without finding the fault, but in my defense (not implying that you attacked) i had replaced the ground wire thinking there must have been a break in it causing the issue in the beginning. not so obviously! I also reverted to the previous driver and tried again too.

    also, i found it very odd that it wasnt just when the usb was connected, it happened if usb was connected while power source already connected. usb connected alone, no problems. power supply connected alone, no problems. it is only when both are connected regardless of which one is connected first.

    i think it happened after updating the driver, why did i update the driver? i had a wrong entry in interface settings and wasn’t connecting to simtools, so I updated the driver thinking that may be the issue. then corrected entry in interface settings. Not 100% sure if that’s when it happened or not as I was moving back and forth between pc and laptop at the time, but was certainly around that instance.
    all other usb devices on the pc work just fine, no issues!

    this ones doing my head in! any assistance would be greatly appreciated
  5. Haydn

    Haydn New Member Gold Contributor

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    i still dont have this sorted, if anyone has any ideas, id really love to hear them, and appreciate their input!
    thanks.
  6. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    Do you mean you have not identified the source of the short?
  7. yellofella

    yellofella Member

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    hi guys
    I might have a few pointers that may help you.
    Firstly the short circuit you mentioned sounds like a 12v short to 5v logic ground. It would take a lot more current than any usb can provide to fry the cable. I would not plug it in to your pc as noorbeast said as it will break some hardware. The only reason i can think of why it will work on your laptop is that your laptop was running on battery at the time of testing and the laptop not being connected to mains ground like the power supply is wouldn't create the short. The pc power supply is always connected to mains ground as the power supply for your motors is so will short. You have probably got away with not damaging your pc motherboard due to the power supply in the pc tripping to protect it but i wouldn't push your luck.

    DO NOT stack the MM on the uno as a shield, use jumper wires to connect as this is probably where your short is. The soldered connector or where you soldered the wire into the MM is probably touching the usb connector of the uno. This will put 12v down the usb ground and cause the problem you have.

    Post some pictures of your wiring so members can spot any faults.
    Test your MM's work properly as per silentchill's video in the FAQ's as a good percent are faulty.

    As to the motor jitter and noise problem.
    You will probably have to deal with this the best you can in the software settings of the SMC3 as a good fix for it isnt easy. You will need to use shielded cable for the potentiometers and only ground the shield
    at the arduino end of the cable. Now the arduino uno was not built for a single purpose but as a development board for an endless amount of different projects and as such does not have separate digital and analogue ground planes so you will always get digital switching noise on the analog signal. This is why the potentiometer reading seems to jump about a bit when stationary. I have solved this completely on my sim by building a pcb for the SMC3 that has 3 MM's in half bridge mode, has the atmega 328 imbedded on the pcb as well as separate digital/ analogue ground planes and loads of decoupling built in
    here is a pic. IMG_0067.JPG
    hope this helps guys
  8. Haydn

    Haydn New Member Gold Contributor

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    yes the short.
  9. Haydn

    Haydn New Member Gold Contributor

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    thank you very much for your in depth reply. i really like your idea about mains grounding, but from memory im pretty sure the laptop was plugged into mains power too. perhaps the laptop runs off battery all the time and just charged from mains and wether thats enough to seperate the operation side of things from mains ground i dont know...
    MMs are not stacked and tested MMs on arrival.
    the PC power supply never tripped, in fact the PC showed no effect from the short whatsoever.
    the jitter/noise issue i was getting on top of before i started frying wires, so not concerned with that at the moment but will certainly refer back to your notes when i get past this current issue.
    i will get some photos of current setup, hopefully get to do that later today.

    your help is very appreciated, thanks.
  10. yellofella

    yellofella Member

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    Hi @Hayden
    Just read the post properly and looked at your pictures/video all of which i didnt do before my last post so was just generalizing over the most common problems that members have and the reason for your short. It seems that your problem is a new one that ive not encountered before but im up to the challenge of helping you sort it. We can deal with the motor jitter at the same time but for me to help you will have to do all the testing as im on the other side of the planet.
    From what i can see in the pictures you are using mostly the same hardware as i am
    arduino uno (atmega 328p)
    motormonster
    12v led power supply
    200w motors (mine are pgsaw from Canada but are much the same)
    So it shouldn't be to difficult to find to problem between us. We will have to go back to basics a bit and test everything but we will sort it buddy.
    Ok firstly we need to test arduino, the usb serial connection and the usb port. Go to the examples in the arduino ide and put the analog read serial sketch onto the arduino uno. Connect a pot to A0-5v-gnd on the arduino, open the serial monitor and check you have changing values when you turn the pot. If you get changing values then the arduino, usb serial and pot is checked ok and we move on. (might as well test the other pot as well).
    Next check the power supply and motors. Connect the motor directly to the 12v of the power supply and ground and turn the power on. The motor should reach max speed and continuously turn in one direction. If it does turn off the power and reverse the 12v and ground of the motor connections at the power supply and turn the power on again. The motor should turn max speed in the other direction continuously. If it does then check the other motor the same way. If both motors turn max speed in both directions then both the motors and the power supply are checked ok and we move on. Power supply may not be able to supply enough current for both motors but we will get to that later if we need to.
    Ok this is where it gets interesting, testing the motormonster. You will need a multimeter to do the testing so if you dont have on then you will need to get one. I could explain how to do the testing but @SilentChill has made a video in the FAQ of how to test properly which will help you more.
    https://www.xsimulator.net/communit...-monster-moto-clones-and-problems.9059/page-4
    You will need to check and double check until you are sure they are ok as this is most probably where your problem is going to be and possibly your short. The build quality and testing of some of the cheap Chinese clones is shocking at best but there are some good ones too. I got mine from flux workshop on amazon and all 3 i ordered were 100%, kind of threw me when testing as to weather i was testing properly lol.
    Download the SMC3 software as it has its own setup software to get closed loop motor control for each motor before you open simtools to help keep it simple and you will need this for testing the motormonster.
    https://www.xsimulator.net/communit...3dof-motor-driver-and-windows-utilities.4957/
    The SMC3 is a seriously good bit of software that i use myself and would probably go as far as to say that you couldn't do better on an arduino uno it is that good. Follow the tutorial on how to connect all the wires and install the software and setup. Use the same usb port that you tested the arduino on.
    You have to use shielded cable for your pots or you will never get rid of the jitter. The pot is a sensor that is right next to a powerful motor which produces a huge magnetic field (emi) to turn. The wires connecting the pot to the arduino are acting as antenna to pick up the magnetic field from the motor. You have to stop this to get good performance from the motors. Get an unused usb cable and cut the ends off. Solder one end to the pot id use red, black and white and cut the green short. On the arduino end only connect the red/black/white and the shield to ground. The shield will carry any emi to ground. (shield being foil or braided wire around the cables).
    Report back buddy with the results of all the testing and some pictures of your wiring if you can. From there we will get into some settings in the smc3 if you have any trouble setting things up.
    Hope this helps buddy.
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  11. Haydn

    Haydn New Member Gold Contributor

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  12. Haydn

    Haydn New Member Gold Contributor

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    Hi Yellofella, so sorry for the delay in getting back to you, ive had one helluva week last week and sons racing yesterday, i tried to upload photos mid week, but unfortunately didnt work. anyway, these pics should upload hopefully.
    do you really think i need to go back to the basics when everything is working fine when connected to the laptop?
    i do have a multimeter and i purchased 6 MM expecting to find faulty ones on arrival. 5 of the 6 tested fine. (5 sparkfun branded and 1 non branded).
    I had changed both the arduino and both MM for new ones with no change to the problem.
    you'll notice the base material everything is mounted on is aluminum composite and metal support towers(not ideal i know), i thought there might be an issue there, but found no continuity between it and any terminals.
    its been a few months since I last looked at it, and my memory aint the best, so i think i need to go back and do some testing again to get my head around where im at again!
    the wire thats cooking is the neg supply from arduino to mm's and pots (second photo with broken black wire to right of screen) i might try connecting external power supply to arduino rather than usb and see what happens. anyway in the meantime if you spot anything obvious please let me know.
    thanks again for your help.

    Attached Files:

    Last edited: Jul 19, 2020
  13. yellofella

    yellofella Member

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    hi @Haydn
    Sorry for the delay getting back to you, i didn't see your post until now. You should of hit me up using @yelloman tag so i get an alert of your message buddy.
    I had a good look at your pictures and nothing obvious stands out. Did you do all the testing as i mentioned in the last post as you didn't say you had in your reply. Without the results of the testing I'm not sure how I'm going to be much help. As well as the testing i would ditch the aluminium plate (at least for now) and the metal standoffs and find a piece of plywood or plastic to put the arduino and the motor drivers on. Basically just lay them out on a non conductive surface test and try. Take the conductive parts out of the equation for now as they are not needed for your sim to work. I know you mentioned that there was no continuity there when you tested before but removing them guarantees there isnt.
    All testing is going back to basics i guess but when something doesn't work as expected you have to de bug it and that will involve testing. Test all hardware individually and if all checks out ok then the fault must be in the way it is installed or a wiring fault. If you do the testing as i mentioned we should know which one it is and can focus on that area to find the fault.
    Maybe use a thinner cable for the ground wire that keeps blowing for testing as a thinner cable will draw less current before/if it blows a bit like a fuse i guess but might help to protect other hardware. It will produce a higher resistance to ground which is not good practice in electronics but will be better for testing.
    One work around if it works ok on your laptop would be to network your laptop and pc together with a crossover cable and have the pc drive the game and the laptop drive the sim. I would recommend that you find the fault personally as the fault may reappear on your laptop at any moment as you don't know where it is and more importantly you may be on on it if it does.
    Hit me up with the results of all the testing and together im sure we will sort it buddy.
  14. Jeroen

    Jeroen Member

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    Check if wall socket is grounded