Under what circumstances will the servo motor vibrate? How can we solve the problems caused by these servo motor jitters? How are they resolved?

For example, if the acceleration and deceleration time is set too small, the servo motor will produce high inertia jitter when it starts or stops suddenly... Increasing the acceleration and deceleration time can solve this problem.

The following is a selection of analysis by netizens on the causes of servo motor jitter, for your understanding and reference:

One: When the servo motor vibrates at zero speed, the gain should be set high, and the gain value can be reduced. If it vibrates when it starts, it will alarm and stop, it may be that the phase sequence of the motor is incorrect.

Two: 1. When the PID gain adjustment is too large, it is easy to cause motor jitter, especially after adding D, it is especially serious, so try to increase P, reduce I, and it is better not to add D.

       2. There will also be jitter when the encoder wiring is wrong.

       3. If the load inertia is too large, replace the larger motor and driver.

       4. The interference of the analog input port causes jitter. Add a magnetic ring to the motor input line and the servo drive power input line to keep the signal line away from the power line.

       5. There is also a rotary encoder interface motor. Poor grounding can easily cause vibration.

Three: 1. Servo wiring:

    (1) Use standard power cables, encoder cables, control cables, and check whether the cables are damaged;

    (2) Check whether there is an interference source near the control line, and whether it is parallel to or too close to the nearby high-current power cable;

    (3) Check whether the potential of the grounding terminal has changed, and ensure that the grounding is good.

      2. Servo parameters:

    (1) The servo gain setting is too large, it is recommended to re-adjust the servo parameters manually or automatically;

    (2) Confirm the setting of the time constant of the speed feedback filter, the initial value is 0, you can try to increase the setting value;

    (3) The electronic gear ratio setting is too large, it is recommended to restore to the factory settings;

    (4) For the resonance of the servo system and the mechanical system, try to adjust the frequency and amplitude of the harmonic filter.

      3. Mechanical system:

    (1) The coupling connecting the motor shaft and the equipment system is offset, and the installation screws are not tightened;

    (2) Poor meshing of pulleys or gears will also cause load torque to fluctuate. Try no-load operation. If no-load operation is normal, check whether there is any abnormality in the joint part of the mechanical system;

    (3) Confirm whether the load inertia, torque and rotation speed are too large, and try to run with no load. If the no-load operation is normal, reduce the load or replace the driver and motor with larger capacity.

Four: Servo motor jitter is caused by faults such as mechanical structure, speed loop, compensation board and servo amplifier of servo system, load inertia, and electrical parts.

Summary: 1. The jitter caused by the mechanical structure can be divided into two cases:

      1. No-load jitter:

    (1) The foundation of the motor is not strong, the rigidity is not enough or the fixing is not tight.

    (2) The fan blades are damaged, which destroys the mechanical balance of the rotor.

    (3) The crankshaft is bent or cracked. It can be solved by tightening screws, replacing fan blades, and replacing shafts.

      2. If there is jitter after adding load, it is generally caused by the failure of the transmission device. It can be judged that there are defects in the following parts:

    (1) Unbalanced rotation of the belt pulley or coupling.

    (2) The center line of the coupling is inconsistent, so that the motor and the mechanical axis of the transmission do not coincide.

    (3) The transmission belt joint is unbalanced. It can be solved by calibrating the transmission device to make it balanced.

       2. Jitter caused by the speed loop problem: The parameters such as the integral gain of the speed loop, the proportional gain of the speed loop, and the acceleration feedback gain are improper. The greater the gain, the greater the speed, the greater the inertial force, the smaller the deviation, and the easier it is to produce jitter. Setting a small gain can maintain the speed response and is less prone to jitter.

       3. Jitter caused by the fault of the compensation board of the servo system and the servo amplifier: the motor suddenly loses power and stops during the movement, resulting in a large jitter, which is related to the improper setting of the servo amplifier BRK terminals and parameters. The acceleration and deceleration time constant can be increased, and the motor can be started or stopped slowly by PLC so that it does not vibrate.

       4. Jitter caused by load inertia: problems with guide rails and screw rods cause the load inertia to increase. The rotational inertia of the guide rail and the lead screw has a great influence on the rigidity of the servo motor drive system. Under a fixed gain, the larger the rotational inertia, the greater the rigidity, and the easier it is to cause the motor to shake; the smaller the rotational inertia, the smaller the rigidity, and the less likely the motor to shake. . It is possible to reduce the moment of inertia by replacing the guide rail and lead screw with a smaller diameter, thereby reducing the load inertia, so that the motor does not vibrate.

       5. Jitter caused by the electrical part:

      1. The brake is not turned on, and the feedback voltage is unstable and other factors. Check whether the brake is turned on. By adding the encoder vector control zero servo function, the torque is reduced to output a certain torque to solve the jitter. If the feedback voltage is abnormal, first check whether the vibration period is related to the speed. If it is, check whether there is any fault in the connection between the spindle and the spindle motor, and whether the spindle and the pulse generator installed at the tail of the AC spindle motor are damaged. Then the printed circuit board should be checked for faults, and the circuit board needs to be checked or readjusted.

      2. The sudden vibration of the motor during operation is mostly caused by the lack of phase. It is necessary to check whether the fuse melt is blown, whether the switch is in good contact, and measure whether there is electricity in each phase of the power grid.