Servo motors, as a key component in industrial automation, provide precise position, speed, and torque control for many applications. However, jitter during operation is a common problem. Jitter not only degrades motor performance but can also negatively affect production efficiency and product quality. Understanding the causes of servo motor jitter and applying appropriate mitigation strategies is therefore important.
1. Mechanical causes and solutions
Mechanical structure issues are often a direct cause of servo motor jitter. No-load jitter can result from an insecure motor base, insufficient stiffness, or loose fasteners. Remedies include tightening screws and reinforcing support structures to improve stiffness and stability. Damaged fan blades or a bent shaft can also cause no-load jitter; replace damaged components promptly.
Jitter that appears after adding load is often related to the transmission. Causes include unbalanced pulleys or couplings, coupling centerline misalignment, and unbalanced belt joints. Solutions include correcting the transmission alignment, adjusting the coupling centerline, and replacing pulleys or couplings with better balance.
2. Speed-loop issues and tuning strategies
Incorrect speed-loop parameter settings are another common cause of servo motor jitter. Parameters such as speed-loop integral gain, speed-loop proportional gain, and acceleration feedback gain directly affect system stability. Excessive gains can produce large inertial forces that lead to jitter. When setting these parameters, balance the motor's dynamic requirements against system stability. Reducing gain values can help reduce jitter in many cases.
3. Servo system faults and handling
Faults in the servo compensation board or servo amplifier can also cause motor jitter. For example, a sudden power loss during operation can produce significant jitter. Such issues are often related to wiring at the servo amplifier BRK terminal or to incorrect parameter settings. Mitigations include increasing acceleration and deceleration time constants and using a PLC to implement gradual motor start and stop to reduce jitter. Regular inspection of the servo system's hardware and software state is also important to prevent jitter.
4. Load inertia causes and improvements
Changes in load inertia can lead to servo motor jitter. Components such as guide rails and ball screws are important parts of the transmission system, and their rotational inertia significantly affects motor rigidity. With fixed controller gains, higher rotational inertia makes the motor more prone to jitter. Consider using smaller-diameter guide rails and ball screws to reduce rotational inertia and improve stability.
5. Electrical causes and troubleshooting
Electrical issues can also cause servo motor jitter. Examples include a brake not released, unstable feedback voltage, and phase loss, all of which can destabilize motor operation. Check that brakes are released, ensure feedback voltage is stable, and verify that all supply phases are present. Regular inspection of electrical wiring and equipment helps identify and resolve potential problems, reducing jitter incidence.
In summary, servo motor jitter can result from a variety of causes, including mechanical structure, speed-loop tuning, servo system faults, load inertia, and electrical issues. Addressing jitter requires systematic diagnosis of each potential factor and the application of appropriate corrective measures. Regular maintenance and training for operators can also help prevent jitter and ensure stable servo motor operation.
