Introduction to Servomotor Encoders
There are many types of encoders, with the most commonly used being absolute encoders, incremental encoders, and rotary transformers, as well as some higher-level communication encoders. For servos, in order to achieve high performance and precision, the encoder's resolution must be increased. Common servomotor encoders have 2000-2500 lines (pulses/revolution), but the higher the line count, the more expensive the encoder, so it is necessary to understand the requirements of the control system to choose the most suitable encoder.
For incremental encoders, which are commonly used, the biggest problem is the loss of position when there is a power failure. Therefore, to maintain the position during a power failure, absolute encoders can be used. If mechanical vibration is large, optical encoders are not suitable, and rotary transformers or magnetic encoders must be used.
Speed control of servomotors
Torque control of servomotors
Synchronized tracking of mechanical positions (multiple transmission points)
Optical encoders rely on the rotation of the encoder disc and the optical receiver to work together. They are very close to each other but cannot touch. However, when there is vibration and the gap between the structure increases, the disc will collide with the optical receiver. When the optical encoder's moving parts collide, their positions change, causing a reduction in accuracy.
Optical encoders must be produced in a dust-free environment. Any dust on the disc will cause the optical encoder to fail. Strict sealing is usually required, especially at the bearing, shell, and wiring points. However, sealing is very susceptible to temperature changes. Due to the heat generated by the environment and the encoder itself, the air and water vapor inside the encoder are expelled when the temperature is high, and the air and water vapor from the outside are drawn in when the temperature is low. This causes condensation on the disc, which directly leads to the failure of the optical encoder.
However, magnetic encoders are greatly affected by electromagnetic interference generated by motors (especially stepper motors), and temperature changes will also cause position drift. In addition, the resolution and accuracy of magnetic encoders are relatively low.
Magnetic encoders also have slower response speeds and cannot handle high-speed motion loads for position feedback. Therefore, magnetic encoders are suitable for the following application scenarios:
Point-to-point reciprocation positioning with low accuracy requirements, such as material handling, material sorting, large equipment positioning control, general robot positioning.
Low speed variation in continuous running, such as AGV wheels, conveyor belt transmission, inverter motor feedback.
High-speed running in one direction, such as electric spindles.
Motion control scenarios with small load inertia.
Feedback for stepper motors and brushless motors.
Note: Please double check the translation for any errors or omissions.