Hello, please help with jittery motors

Hello everyone, this is my first post here. I've built a 2dof machine using 12v motion dynamic 200w worm drive motors, 12v 50amp psu, motomonster driver and Arduino uno with racingmat's code. After a rather steep learning curve, I've eventually got everything talking to each other and getting movement where and when it's needed. My problem is as you'll see in the video that the motors have an awefull jittery sound and action when holding position with any amount of load on them. Also you'll note when a bit of force by hand is applied to those jittery motors, the power is cut allowing the motor to become idle and drop.

Hi,
I had the same problem using similar components. In my build I used an arduino with 2 motomonster, one for each motor. I havent seen racingmat's code but I'm using SMC3 and I observed this sound could be caused by too many calculations per second (the number of times the motor tries to drive to the potentiometer position, and since the pot value fluctuates a bit this could cause this particular sound), or by not ground isolating the motors.
If it's because of too many calcs per second you could lower this parameter a bit and it should become less noisy. In the PID I also observed that increasing slightly the PWMin value this improves.
The PWMin value means that the motor will always maintain some current so it becomes easier for it to move from a stand still position.
I don't think that in your case is due to the motor nor being ground isolated. In this case you should have had problems with the monster as I did.

Thanks so much for your response, it’s greatly appreciated! Over the past few days I’ve done a lot of reading of other posts to try and come to a solution on this. I’ve read everything from increasing PWM to cheap and nasty pots to motor/gearbox backlash to PID to every other conceivable setting. I have noted when the pots are not attached to the motors and I slowly turn them, either side of the centre position has the MM power indicator led flashing rapidly rapidly as in too many calcs as you say.
I tried racingmats “ultrasonic pwm code” at 20khz and that just didn’t work at all. Apart from that I’m not sure how to change pwm in his original 2dof code, nor do I know how to change pid in his code. Code can be found here.
https://www.xsimulator.net/communit...-and-2-pins-direction-hbridge-motomonster.67/
I’ve played with all the settings in SimTools to no avail.
I would try the SMC3 code if I knew it ran on Arduino uno, but I’m not sure as it states it was intended for the R 3. Do you think this would make a difference? Perhaps not if you had the same issue but with SMC3. What did you do exactly to rectify the problem? I have another MM if you think 2 will be the solution. thanks again for your response and time.
Cheers

Hi, as you can see i'm also new to build 2dof. My parameters are arduino uno + IBT_2 .... I have a very similar problem with motor vibrations .... I don't know if this will solve your problem but as in SMC3 I set the value Deadzone above the value of 6 the squeaking and vibrations cease ...
Regards.

Hi, I had this problem mainly because the motors were not ground isolated so the current made it's way trough a bolt I have conecting the two motors and drove the monster crazy. This is a common problem for this motors as they are built this way from the factory. I ground isolated one of them and then they became less noisy but were still making some noise.
Another problem I had wich was fixed too when I isolated the motor were the power supply turning off when the motor had to work harder.
At this point my sim worked perfectly except for the noise it made, I think this is the step where you are at.
So if you go for SMC3, that should work for you, you have a parameter in the SMC3 utils program that is Fpid/x where as you increase x it will reduce slightly the calculations per second.
You can find a complete guide to install SMC3 here https://www.xsimulator.net/communit...3dof-motor-driver-and-windows-utilities.4957/
In this guide are explained all the parameters in smc3.
After I made some adjustments in SMC3 the noise dissapeared so I think this could work for you.
I'll attach a photo of the smc3 utils program, as soon as I can I'll make one with the parameters I have at the moment so you can compare them and see if they work for you.

Anyway I'll take a look at racingmat's code in case I could find something that could work

Thanks for your reply, currently I’m not using SMC3 because I wasn’t sure it’d work on the uno, obviously it does if your using a uno. I think I’ll try SMC3 and let you know how I get on, thanks.

Thanks again for getting back to me, I have checked continuity between chassis and motor leads and there’s no continuity so I don’t think there’s an issue there with grounding. I believe it’s mainly an issue with wiper motors. Tell me if I’m doing it wrong! Electronics ain’t my forte! I think I’ll try SMC3 and see where that takes me, I think the wiring of the Arduino and MM are a little different, so I’ll check that first and go from there, thanks and I’ll let you know how it goes, cheers!

In fact, SMC3 has been written particularly for Arduino Uno. See the first sentence of the SMC3 Tutorial: "The SMC3 is a "Simulator Motor Controller for 3 Motors" written for the Arduino UNO R3."

Forgi

Forgive my ignorance, i did read that, hence my wording “I’m not sure as it states it was designed for the R3” I presumed the r3 was a different version of the Uno. I was wrong, not the first time. cheers.

Hi,
one thing I did with the motors is opening them and cleaning them properly as they were from a junkjard. This made them drive better but yours look new and clean.
Yeah, the wiring is different and you have to be cautious with that, just follow the diagram included in the post and all should work right from the start. One change I made was connecting the 5V input from the MM directly to the 5V output from the power supply but should work the other way too.

I'll try to attach a photo of the configuration I have in SMC3 in case this helps you.

Let me now how does this works with your build and I´ll try to help as much as possible

Cheers

Thanks mate, I’m a little further ahead now, I rewired everything to suit SMC3, loaded the code and utilities. Motors sound a lot healthier now, but MM keep cutting out. Did some maths and given MM’s only handle a continuous load of around 15amps per side, I’m pushing the limit with 200w motors (16.6amps each). So I’m hoping the answer is to use the 2 MM outputs to power one motor and fit another MM for the 2nd motor. I’ll give it go tomorrow and let you know how it goes, thanks again!

Great! This is exactly what I did because of the same problem, the MM cutting out. After that they are working perfectly and now what limits me is the power suplly.
Hope this works for you!
Cheers

Update, think one of the MM are playing up, so everything is on hold till I get some new ones.

What do you refer by one of the Mm are playing out. I think I don't understand it sorry

Stopped working properly!

Oh wow, I´m sorry. One of the MM that were sent to me was bad too (In total I had to order 3). Let me know when it arrives if need some help!
Cheers

Update, ok! Well I got the new MM’s redid all the wiring nice and neat, mounted everything in an enclosure hooked up to laptop (from which I’ve been doing all testing and set up) all appears to be working fine. It was always intended on running the sim from my desktop pc, so I pulled the Usb from the laptop and plugged into pc and immediately my ground wires from arduino fried. I repaired the wiring and plugged USB back into laptop, everything ran fine again so plugged USB into pc again and bang, the ground wires fried again. Tried several other ports on the pc and the same thing happens. This is only happening with the motors power supply turned on. The system connects to the pc fine until the power supply is turned on and then bang! (Not when connected to the laptop though). I don’t get how plugging into a different computer can do this, all other USB devices are running fine from the pc. Anyone have any clues?

Wow, I'm surprised by this problem. What cables do you have connected to the power supply? Only the 12V and ground to the MM? Maybe connecting the arduino ground cables to any ground cable in the power supply fixes your problem, but I have no idea on what could cause this. I suppose you have the same config in both pc's so it's not a software config problem in your desktop pc.