Reasons and solutions for servo motor vibration!

In which situations can the servo motor shake? How can we solve the problems caused by servo motor vibration? How did they resolve each issue?

For example, if the acceleration and deceleration time are set too small, the servo motor may experience high inertia shaking when suddenly started or stopped Increasing the acceleration and deceleration time separately can solve this problem.

Below is a selection of analysis conducted by netizens on the causes of servo motor vibration, for everyone to learn and use for reference:

Viewpoint 1:

When the servo motor shakes at zero speed, the gain should be set high to reduce the gain value. If there is a slight shaking during startup, the alarm will stop, and the maximum possibility is that the motor phase sequence is incorrect.

Viewpoint 2:

1. When the PID gain adjustment is too large, it is easy to cause motor vibration, especially when D is added, which is particularly serious. Therefore, it is best to increase P and reduce I, and it is best not to add D.

2. When the encoder wiring is connected incorrectly, there may also be shaking.

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

4. Analog input interference causes jitter, and a magnetic ring is added to the motor input line and servo driver power input line to keep the signal line away from the power line.

5. There is also a type of rotary encoder interface motor, which can easily cause vibration due to poor grounding.

Viewpoint 3:

① Servo wiring:

a. Use standard power cables, encoder cables, control cables, and cables for damage;

b. Check if there are interference sources near the control line and if they are parallel or too close to the nearby high current power cables;

c. Check if there is any change in the potential of the grounding terminal to ensure good grounding.

② Servo parameters:

a. The servo gain setting is too large, it is recommended to manually or automatically adjust the servo parameters;

b. Confirm the setting of the speed feedback filter time constant, with an initial value of 0. You can try increasing the setting value;

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

d. Resonance between the servo system and the mechanical system, attempting to adjust the frequency and amplitude of the notch filter.

③ Mechanical system:

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

b. Poor engagement of pulleys or gears can also lead to changes in load torque. Attempt to operate without load. If the no-load operation is normal, check if there are any abnormalities in the bonding part of the mechanical system;

c. Confirm if the load inertia, torque, and speed are too large, try running without load, and if the no-load operation is normal, reduce the load or replace the driver and motor with a larger capacity.

Viewpoint 4:

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

1. The shaking caused by mechanical structure can be divided into two situations:

1) No-load jitter:

a. The foundation of the motor is not firm, the stiffness is insufficient, or the fixation is not tight.

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

c. The shaft is bent or cracked. It can be solved by tightening screws, replacing fan blades, replacing machine shafts, and other methods.

2) If the shaking occurs after loading, it is generally caused by a malfunction of the transmission device, and it can be determined that the following parts have defects:

a. The belt pulley or coupling rotates unevenly.

b. The centerline of the coupling is inconsistent, causing the motor to not coincide with the mechanical axis being transmitted.

c. The transmission tape joint is unbalanced. It can be solved by correcting the transmission device to balance it.

2. Jitter caused by speed loop issues:

Improper parameters such as speed loop integral gain, speed loop proportional gain, and acceleration feedback gain. The greater the gain, the faster the speed, the greater the inertial force, the smaller the deviation, and the more likely it is to produce jitter. Setting a smaller gain can maintain speed response and prevent jitter.

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

The sudden power failure and stop of the motor during movement cause significant shaking, which is related to the improper setting of the servo amplifier BRK wiring terminals and parameters. The acceleration and deceleration time constant can be increased, and the PLC can be used to slowly start or stop the motor to prevent it from shaking.

4. Jitter caused by load inertia:

Problems with the linear guide rail and screw lead cause an increase in load inertia. The rotational inertia of the guide rail and lead screw has a significant impact on the rigidity of the servo motor transmission system. Under fixed gain, the greater the rotational inertia, the greater the rigidity, and the more likely it is to cause motor vibration; The smaller the moment of inertia, the less rigid it is, and the less likely the motor is to shake. The motor can be stabilized by replacing smaller diameter guide rails and screw rods to reduce rotational inertia and load inertia.

5. Vibration caused by electrical components:

a. Factors such as brake not being turned on, unstable feedback voltage, etc. Check if the brake is turned on, and use an encoder vector to control the zero servo function, using a torque reduction method to output a certain amount of torque to solve the vibration. If the feedback voltage is abnormal, first check whether the vibration cycle is related to the speed. If it is related, 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 it is not related, check whether there is a fault on the printed circuit board. It is necessary to check the circuit board or adjust it again.

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