Question Actuator oscillation/vibration problem

Hello everyone, I have a serious and inconvenient problem.
I built a platform with 4 actuators (D-Box type), but all 4 actuators produce a vibration when I put a payload on it.
I'm using SCM3 V1.7 (with softstart) with Arduino.
As soon as I insert the USB cables, the actuators move perfectly to the center, but after a few seconds they start to oscillate/vibrate up and down repeatedly of about -/+ 2 millimeters, even without using Simtools, without using any game, without using SMC3Utils.
NOTE: If the actuators have no payload, there will be no vibration/oscillation.
I've already tried to change the PID values and the dead time, but I don't get any improvement.
My idea would be to lock the motors or disable power to the motors from software when not using Simtools or not starting the game.
So if Arduino does not receive any telemetry, the BREAK pin of the driver receives a 0V signal which activates the MOSFETs to brake the motor.

Is this already possible to do or do you have to modify the Arduino sketch?

Show is your smc3 untils settings

Fpid = 10
Kp = 80
Ki = 0
Kd = 0
Ks = 1

Fpwm = 5
PWMmin = 0
PWMmax = 50
PWMrev = 0

Max Limits = 0
Clip = 125
Dead Zone = 0

try this

Fpid = 1
Kp = 1
Ki = 0
Kd = 0
Ks = 1

Fpwm = 15 khz
PWMmin = 0
PWMmax = 225
PWMrev = 225

now slowly increase KP till the motors move

Ok will try this solution and then I will write the result.
Thanks in the meantime.

I too think that the oscilations point towards PID tuning issues. I can't help you with SMC settings though, sorry.

Another possible source of those oscilations I could imagine is if the position sensing (encoder?) is inaccurate or has a mechanical hysteresis or excessive latency. Maybe investigate in that direction...

Wish you success

Hi everybody.
I did the test that "gadget999" recommended to me, it seems to have improved a little (but very little)...
So I continue to have this oscillation problem, the actuators go up and down continuously by +/- 2 mm.
If I don't put the payload on top the oscillations disappear, but if I press my hands on the actuator with my body, it starts to oscillate.

As you say "Dirty", it could be a PID problem, I don't know...
There are no mechanical tolerance gaps in the actuator, I am using excellent quality potentiometers (not encoders).

Questions: Can it depend on how often the driver drive works? It works at maximum with a frequency of 1Khz for the brushless motor. Maybe if I use another driver with a frequency of 15Khz I could solve the problem?

Another thing: is there a way to bring the piston all the way down when you're not using the game? Currently the oscillations occur even without starting the game.
I read somewhere that you could use a string to bring the pistons to the lower part (rest), the string was this:

STARTUP OUTPUT
[A<128>][B<128>][C<128>]

SHUTDOWN OUTPUT
[A<128>][B<128>][C<128>]

I already tried this solution but nothing happens, as if the string was wrong, I don't know.
Could someone explain to me better how to use these strings correctly?

Thank you all

Hi noorbeast, yes I noticed that by increasing the Dead Zone in SMC3Utils, the oscillations increase...

What do you mean by "resolution"?
I use a Bourns potentiometer with 10cm of total movement (from 0 to 10cm of movement), and 10K of resistance.
In SMC3 the green line (potentiometer) follows the blue line perfectly. I can attach a picture if you want.

what are your current settings ?

Good morning, this is the setup I've been using for a few days.

Hi Noorbeast, I set the values as you told me. But the motors did not move with Kp=400 and Clip and Limit at 255.
I then set Clip to 125, Limit to 0.
So the engines started moving.
The values are:

Kp = 400
Clips = 125
Limit = 0
PWMmax = 5

So the engines started moving.
Obviously very slowly, the potentiometer line does not in fact follow the blue line.
Obviously if I increase PWMmax the green line improves, following the blue line.

With the values in the graph, the motor emits a loud noise when it is stopped at a position, in fact in "manual" mode, every time I click on the right on one of the 3 buttons (up, center, down), the motor stops in position and emits a loud noise, as if it were frying.... So the motor does not oscillate but vibrates and emits a loud noise...

So, I think I have solved the problem 70%.
I set the following values:

Kp = 50
PWMmax = 255

Now the three engines oscillate less.
A question I ask you, what are the following strings for and how are they used?

STARTUP - OUTPUT
[A<128>][B<128>][C<128>]

SHUTDOWN - OUTPUT
[A<128>][B<128>][C<128>]

Thanks in advance

Hi, I also used 10KOM potentiometers and I also had surges and vibrations. I tried to fix this using the settings but it didn't work. then I rigidly connected the potentiometer to the gearbox and removed all the backlash, after which the jumps and vibrations went away

I have seen in people's projects when the potentiometer is connected to the motor via a drive belt, and it was not tensioned enough, I think this will also cause vibration

Hi Airbas72.
My potentiometer is firmly fixed on the actuator with 2 screws, it is not loose, it is not movable.
So I don't think the oscillations depend on the potentiometer.

I have a question: I noticed that in SMC3Utils, if I increase the value of Deadzone, the oscillations increase, whereas by lowering the value the oscillations decrease. So at 0 they almost disappear, but they are still present.
Is there a way to change the dead zone from Sketch? Maybe by reducing the value from the sketch I can solve it much better.
Tell me, thanks