Causes and solutions for servo motor jitter

In what cases will the servo motor vibrate? How can we solve the problems caused by the servo motor vibrating? How are they solved respectively?

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... This problem can be solved by increasing the acceleration and deceleration time respectively.

The following is a selection of netizens' analysis of the causes of servo motor jitter for your reference:

one

Viewpoint 1

When the servo motor vibrates at zero speed, the gain may be set too high, and the gain value can be reduced. If the servo motor vibrates once when starting and then alarms and stops, the most likely reason is that the motor phase sequence is incorrect.

two

Viewpoint 2

1. When the PID gain is adjusted too large, it is easy to cause the motor to shake, especially after adding D, which is particularly serious. Therefore, try to increase P and reduce I. It is best not to add D.

2. Jitter may also occur if the encoder wiring is connected incorrectly.

3. The load inertia is too large, so replace it with a larger motor and driver.

4. Interference at the analog input port causes jitter. Add magnetic rings 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, which can easily cause vibration if the grounding is not good.

III

Viewpoint 3

① Servo wiring:

a. Use standard power cables, encoder cables, and control cables, and check whether the cables are damaged;

b. Check whether there is any interference source near the control line, and whether it is parallel to or too close to the nearby high-current power cables;

c. Check whether the grounding terminal potential has changed to ensure that the grounding is in good condition.

② Servo parameters:

a. The servo gain is set too high. It is recommended to readjust the servo parameters manually or automatically.

b. Confirm the setting of the speed feedback filter time constant. The initial value is 0. You can try to increase the setting value.

c. The electronic gear ratio is set too large, it is recommended to restore it to the factory setting;

d. Resonance between the servo system and the mechanical system. Try to adjust the frequency and amplitude of the harmonic filter.

③ Mechanical system:

a. The coupling connecting the motor shaft and the equipment system is offset and the mounting screws are not tightened;

b. Poor engagement of pulleys or gears can also cause load torque fluctuations. Try running without load. If it is normal when running without load, check whether there is any abnormality in the joint part of the mechanical system.

c. Check whether the load inertia, torque and speed are too large, and try to run it without load. If it runs normally without load, reduce the load or replace the drive and motor with larger capacity.

IV

Viewpoint 4

Servo motor jitter is caused by faults in the mechanical structure, speed loop, servo system compensation board and servo amplifier, load inertia, electrical parts, etc.

Wu

Summarize

1. The vibration caused by mechanical structure can be divided into two cases:

1) No-load jitter:

a. The motor foundation is not firm, not rigid enough or not fixed tightly.

b. The fan blades are damaged, destroying the mechanical balance of the rotor.

c. The shaft is bent or cracked. This can be solved by tightening the screws, replacing the fan blades, or replacing the shaft.

2) If the machine shakes after adding load, it is usually caused by a transmission failure. It can be judged that the following parts are defective:

a. The belt pulley or coupling rotates unbalanced.

b. The center lines of the couplings are inconsistent, causing the motor and the mechanical axis being driven to not coincide.

c. The transmission belt joint is unbalanced. This can be solved by correcting the transmission device to make it balanced.

2. Jitter caused by speed loop problems:

Improper parameters such as speed loop integral gain, speed loop proportional gain, acceleration feedback gain, etc. The larger the gain, the greater the speed, the greater the inertia force, the smaller the deviation, and the easier it is to produce jitter. Setting a smaller gain can maintain speed response and is less likely to produce jitter.

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

The motor suddenly stops due to power failure during operation, causing great vibration. This is related to the improper connection terminals and setting parameters of the servo amplifier BRK. You can increase the acceleration and deceleration time constants and use the PLC to slowly start or stop the motor to prevent vibration.

4. Jitter caused by load inertia:

Problems with the guide rails and lead screws cause the load inertia to increase. The rotational inertia of the guide rails and lead screws has a great influence on the rigidity of the servo motor transmission system. Under fixed gain, the greater 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. The motor can be prevented from shaking by replacing the guide rails and lead screws with smaller diameters to reduce the rotational inertia and thus the load inertia.

5. Jitter caused by electrical parts:

a. The brake is not open, the feedback voltage is unstable and other factors. Check whether the brake is open, add the encoder vector control zero servo function, and use the torque reduction method to output a certain torque to solve the jitter. If the feedback voltage is abnormal, you should first check whether the vibration cycle is related to the speed. If so, check whether there is a fault in the connection between the spindle and the spindle motor, whether the spindle and the pulse generator installed at the tail of the AC spindle motor are damaged, etc. If not, check whether the printed circuit board is faulty, and you need to check the circuit board or readjust it.

b. Sudden jitters during motor operation are mostly caused by phase loss. You should focus on checking whether the fuse is blown, whether the switch contact is good, and measure whether there is electricity in each phase of the power grid.

With these netizens' analysis, do you have a general understanding of the reasons for the servo motor's jitter during operation? In this case, you can check the reasons analyzed in the netizens' opinions. In addition, you can also pay attention to these problems in daily life to avoid the servo motor from jittering during operation.