Question output arm shake problem

The output arm movement encounters shake problem. I use SMC3, arduino and hall potentiometer. I have tested the hall potentiometer, the output is smooth and continuous.

During output testing the situation as follows:
1. When the output value is zero, there is no shake.
2. Adjusting the output to any angle, when the output arm is in place, it starts to shark and cannot stop. (the movement process is smooth)
3. Adjust the output value back to 0, most of the time there is no shake, and about 20% chance of shake again.


I tried increasing the smoothing value in the Axis Assignments setting, but it will not reduce the shake.

what does the pot signal look like in the SMC3 util program ?

have you adjusted the PID settings inside the SMC3 ?

This is a test when I adjusted the potentiometer by hand (no motor connected) , it looks good.

Thanks guys
Based on the experience of drones, I know that adjusting PID is a complicated task so there is no adjustment before. Now I will try to adjust in SMC3.

Without adjusting any parameters, The SMC3 "out mode - triangle" test is as follows, and it looks good.



When I manually adjusted to a angle and stopped (SMC3 out mode - manual), output arm did not shake.

please send us a video/image of the output on the sine wave

setting Kp 300 Ki Zero and Kd zero is a good place to start

(it looks like your Kp number in the triangle test is not big enough)

Thanks SeatTime I will try this.

Sadly, the left motor died yesterday.... and it ’s unclear whether it ’s a motor failure or a drive failure
The sine test is as follows:

If those are the PID settings you actually use its just a P controller though. For that output the math is simply (a Simtools axis, the setpoint - feedback) * single multiplier = motor speed. Other than that you just need to test for what direction they need to run. True its very easy to set P only but its quite a waste of a good PID controller. And theoretically a balanced system will never reach a setpoint using P only.

Thanks to Gadget999&SeatTime, I have tried: Kp 300 Ki 0 and Kd 0, there is no shake now.

What you said is very reasonable, now I shuould start to learn the principle of PID control

your output should track the sine curve exactly - increase the P number so so the motor is working harder and the slowly add D until it is stable

I tried to increase kp to 1000, so... it seems that my motor is too slow?

Kp is not the only parameter. Please try increasing PWMax.

Edit: And have a look here for an explanation of all SMC3 parameters.

Thanks MarkusB, After the PWMmax increased to 150(adding more has no effect), the effect is very good, two curves almost coincide.

I increased the PWMmin to 80 and the curve looks better

Perfect. Note that the rig will probably behave different when you are sitting in it, so that you may need to re-adjust the settings again.

When you are done with configuring the settings in SMC3 Utility, the next step will be to set up Game Engine.

When I did this for the first time, I had very smooth motor movements in SMC3 Utility, but rather jittery movements with Game Engine's output testing.
If you also see this happen, you may need to increase the Fpid value. In my case, I changed it to Fpid/4. After this, the motor movements were also nice and smooth in Game Engine. If this does not help, you also need to decrease Kp.

I will try more adjustments, your tips are very helpful. Thanks MarkusB