What are the causes of inaccurate servo motor positioning?

 

Mechanical Backlash:

Mechanical backlash refers to the slight movement or play that occurs when the direction of motion changes in a mechanical system. It can result from gaps or clearances in gears, couplings, or other mechanical components. Backlash can cause a delay or inaccuracy in the response of the servo motor, leading to positioning errors. Regular maintenance, proper lubrication, and using components with minimal backlash can help minimize this issue.

 

 

 

 

 

Picture from: ISS23-20

 

 

 

 

 

 

 

 

 

Encoder Resolution and Accuracy:

The encoder is a crucial component of servo motors that provides feedback on the motor's position. If the encoder resolution is not set correctly or if the encoder itself has low resolution, it can result in positioning inaccuracies. Ensure that the encoder resolution is properly configured to match the motor's specifications. Consider using encoders with higher resolution for applications that require precise positioning.

 

 

 

 

 

Picture from: ISV57T-090

 

 

 

 

 

 

 

 

 

 

Electrical Noise and Interference:

Electrical noise and interference can negatively impact servo motor positioning accuracy. Common sources of electrical noise include electromagnetic interference (EMI) from nearby equipment or power sources, improper grounding, or inadequate shielding. Implementing proper grounding techniques, using shielded cables, and isolating the servo motor from sources of interference can help mitigate these issues.

 

Insufficient Servo Motor Tuning:

Servo motors often require tuning to optimize their performance. Inadequate tuning of gain parameters, such as proportional gain (KP), integral gain (KI), and derivative gain (KD), can result in positioning errors. Improperly tuned servo motors may exhibit overshooting, oscillations, or sluggish responses, leading to inaccurate positioning. Carefully adjust these parameters based on the specific requirements of the application to achieve better positioning accuracy.

 

Mechanical Resonance:

Mechanical resonance occurs when the natural frequency of a mechanical system coincides with the excitation frequency, resulting in excessive vibration and reduced accuracy. Resonance can lead to positioning errors and instability in servo motor systems. Identify and address mechanical resonance issues by adjusting the system's stiffness, damping, or adding vibration isolation measures. Avoid operating the servo motor at frequencies that coincide with the system's resonance frequencies.

 

Systematic Errors and Calibration:

Systematic errors, such as non-linearities or hysteresis in the mechanical system, can contribute to inaccurate positioning. Calibration of the servo motor system is essential to compensate for these errors. Perform regular system calibration, including measuring and compensating for any non-linearities or offsets in the positioning. Calibration routines can be implemented using software tools or specialized equipment to improve positioning accuracy.