Absolute vs Incremental Encoders: Difference and Comparison

The encoding principle is a common method of categorizing encoders. The detection of angular and linear motion is critical in the electronics factory’s machine control.

Key Takeaways

1. Absolute encoders provide a unique output for each position, ensuring accurate position tracking, while incremental encoders only detect changes in position.
2. Incremental encoders are more affordable and simpler to implement than absolute encoders.
3. Absolute encoders maintain position information even after power loss, whereas incremental encoders require a homing sequence to determine the position upon power restoration.

Absolute vs Incremental Encoders

Absolute encoders provide a unique digital code for each shaft position, while incremental encoders measure the relative movement of the shaft from its previous position. Absolute encoders are more expensive but more accurate. Incremental encoders are less expensive with a high resolution.

At each point of rotation, an absolute encoder delivers a unique position value or data word that represents the encoder’s absolute position. The absolute encoder can provide you with the exact position of the rotating axis that it monitors from the moment it is turned on.

An incremental encoder is a type of encoder that translates rotational movement or rotor position into an analogue or digital code in order to determine position or motion. One of the most common types of rotary encoders is an incremental encoder.

Comparison Table

Parameters of Comparison	Absolute Encoders	Incremental Encoders
Basics	An absolute encoder has a special identifier for each turbine shaft that specifies the encoder’s absolute position.	An incremental encoder produces an output signal every time the shaft turns a specific angle, with the number of generated pulses corresponding to the shaft’s angular position.
Operating Principle	An absolute encoder is made out of a data type disc that is positioned on the axis and spins with it.	An incremental encoder produces an output signal for each increase of angular position of the shaft, which is calculated by measuring the output strokes recognize.
Cost Efficiency	More complex, more costly.	Less Complex, less expensive.
Works as a	Stopwatch	Clock
Stability	Absolute encoders have the potential to provide higher performance, more precise output, and reduced total costs.	An incremental encoder must be switched on at all times during the device’s operation.

What are Absolute Encoders?

Each axis position in an absolute encoder is assigned a different code that specifies the encoder’s absolute position. It immediately generates a digital output representing the absolute displacement.

An absolute encoder’s disc employs a Gray code, which changes one bit at a time, reducing encoder communication mistakes. The resolution is expressed in bits, which correspond to the number of distinct data words for each revolution.

Absolute encoders can be used in single-turn and multi-turn configurations. The output of the single-turn encoder repeats every rotation and provides position data for a complete 360° rotation of the shaft.

What are Incremental Encoders?

The angular position of the shaft is converted into digital or pulse signals via an incremental encoder, which is an electro-mechanical device. It produces a fixed number of cycles every revolution, one for each step of the rebellion.

When the device is turned on or reset, it starts counting from zero and creates an output signal for each movement of the shaft. The incremental encoder generates a pulse for each incremental step in the rotation.

Despite the fact that incremental encoders do not produce absolute positions, they could provide a good degree of precision at a low cost. The tachometer encoder generates a short pulse whose frequency determines the speed of movement.

Main Differences Absolute and Incremental Encoders

1. An absolute encoder acts as a stopwatch, and an Incremental encoder acts as a clock.
2. Absolute encoders have the potential to provide higher performance, more precise output, and reduced total costs. On the other hand, an incremental encoder must be switched on at all times during the device’s operation.

References

1. https://www.osapublishing.org/abstract.cfm?uri=ao-35-1-201
2. https://ieeexplore.ieee.org/abstract/document/4913270/