The first possibility is that the PID gain adjustment is too large, especially after adding D. Therefore, we should try to increase P, reduce I, and try not to increase D.
The second possibility is that the wiring of the servo motor encoder is connected incorrectly, causing the motor to vibrate.
The third possibility is that the load inertia of the motor is too large, causing tremors.
The fourth possibility is that the analog input port of the servo encoder has interference, which makes the motor vibrate. This requires us to add a magnetic ring to the servo motor input line and the servo drive power input line, and keep the signal line away from the power line.
Do you know other causes the servo motor to vibrate too much?