What is the cause of servo motor jitter?

Release time:

2023-03-03

 A, mechanical structure caused by the jitter can be divided into two cases.

  1) No-load jitter.

  A. The foundation of the motor is not solid, not rigid enough or not fixed tightly.

  B. Fan blade damage, destroy the mechanical balance of the rotor.

  C. The machine shaft is bent or broken. It can be solved by tightening the screws, replacing the fan blades and replacing the machine shaft.

  2) If the shaking after loading is generally caused by transmission failure, the following parts can be judged to be defective.

  A.The rotation of the pulley or coupling is unbalanced.

  B. Coupling centerline inconsistency, so that the motor and the driven mechanical axis do not overlap.

  C. The drive belt is not balanced joint. It can be solved by correcting the drive to make it balanced.

  2. Jitter caused by speed loop problems.

  The parameters of speed loop integral gain, speed loop proportional gain and acceleration feedback gain are not appropriate. The greater the gain, the greater the speed, the greater the inertia force, the smaller the deviation, the more likely to produce jitter. Setting a smaller gain can keep the speed response and not easily produce jitter.

  3. Jitter caused by the failure of servo system compensation board and servo amplifier;

  The motor suddenly loses power and stops moving with great jitter, which is related to improper servo amplifier BRK terminal and setting parameters. The acceleration and deceleration time constants can be increased, and the motor can be started or stopped slowly by PLC to prevent the motor from shaking.

  4. Jitter caused by load inertia.

  The load inertia increases due to the problem of guide rail and screw. The rotational inertia of the guide rail and screw has a great impact on the stiffness of the servo motor drive system. Under fixed gain, the greater the rotational inertia, the greater the rigidity, the more likely to cause motor jitter; the smaller the rotational inertia, the smaller the rigidity, the less likely to cause motor jitter. By replacing smaller diameter guide rails and screws, motor shaking can be prevented, thus reducing the rotational inertia and thus the load inertia.

  5. Jitter caused by electrical components.

  A. The brake is not open and the feedback voltage is unstable. Check whether the brake is open, and solve the jitter by increasing the encoder vector control zero servo function and outputting a certain torque through torque reduction. If the feedback voltage is abnormal, first check whether the vibration cycle is related to the speed. If yes, check whether the connection between spindle and spindle motor is defective, whether the spindle and the pulse generator installed at the end of the AC spindle motor are damaged, etc. If it is not related, check whether the printed circuit board is faulty, check the board or readjust it.

  B. Sudden jittering during motor operation is mostly caused by phase loss. It is important to check whether the fuse is blown, whether the switch contacts are intact, and measure whether there is power in each phase of the power grid.