Rotary encoders are electromechanical devices that are commonly used in automated industrial machinery and on servomotors. These devices are sensors that track the rotation of motor shafts and generate information regarding the digital position and motion of the motor shafts; the information gathered is converted into an analogue or digital code.
How Do They Work?
Rotary encoders, or shaft encoders, measure the number of rotations, the rotations angles and rotational positions of motor shafts or axles.
These devices encode the position of shafts using the following methods:
- Standard binary encoding.
- Gray encoding.
- Single track gray encoding
- Absolute encoder output techniques.
Different Types of Rotary Encoders
Rotary encoders fall into two main categories: Absolute encoders and incremental encoders. These encoders are used in the following industries:
- Machine and plant engineering.
- Renewable energy.
- Oil and gas.
- Doors, gates and elevators.
Absolute Rotary Encoders
These devices are composed of multiple detectors and a disc with multiple tracks. Absolute encoders track the rotation of shafts using gray encoding. They sense the rotation position of a shaft by directly reading the output code. The light that passes through the slits in the disk of the encoder, from the shaft, is converted into a digital signal.
The following benefits are associated with absolute rotary encoders:
- It keeps record of the shaft’s position, even after a power outage.
- It has speed, scaling, preset and fieldbus functions.
- It continuously measures the position of a shaft.
Incremental Rotary Encoders
Incremental encoders are the most commonly used. These encoders detect the motion of a motor shaft. Unlike absolute rotary encoders, the incremental encoders only have two sensors; however, this does not affect their performance.
The following benefits are associated with incremental rotary encoders:
- Good for speed, direction and position monitoring.
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