1. Introduction
In 2026, precise motion control is a critical requirement for industrial production. From precision machine tools to complex robotic systems, encoders provide the feedback needed to control position, speed and acceleration. The choice between incremental and absolute, optical and magnetic technologies determines the reliability of the control system and its ability to work under conditions of high loads, electromagnetic interference and pollution.
2. Historical evolution
| Period | Development of technology |
|---|---|
| 1960s | The appearance of the first optical incremental encoders for CNC machines. |
| 1980s | Implementation of absolute encoders with parallel output. |
| 1990s | Development of industrial networks (Profibus, CAN) and serial interfaces. |
| 2000-no | Wide implementation of magnetic encoders based on the Hall effect. |
| 2010s+ | Real-time digital interfaces (BiSS, SSI, EnDat 2.2), built-in diagnostics. |
3. Principles of work
Optical encoders use a light source (LED), a slotted (or patterned) disc, and a photodetector. When light passes through the slits, electrical impulses occur. For incremental sensors, the resolution is determined by the number of pulses per revolution (PPR). For absolute sensors, the disk has a unique code (for example, Gray code) that allows you to determine the angular position immediately after switching on.
Magnetic encoders use a permanent magnet on the shaft and Hall sensors or magnetoresistive sensors. The change in the magnetic field when the shaft rotates is converted into an electrical signal. This provides superior resistance to dust, oil and vibration according to EN 60529 (IP67 and higher).
The basic resolution formula for an incremental encoder is: R = 360° / N, where N is the number of pulses per revolution. For high accuracy, interpolation of sinusoidal signals is used.
4. Modern technologies and market leaders
The following manufacturers will be leading the market in 2026:
- Heidenhain: ECN/EQN series (optical absolute encoders with EnDat 2.2 for high accuracy).
- SICK: AFS60 series (magnetic absolute encoders for industrial applications).
- Baumer: EAL580 series (heavy-duty magnetic encoders).
5. Selection criteria
| Criterion | Incremental | Absolute |
|---|---|---|
| Position after power-on | Unknown (needs calibration) | known (instant) |
| Complexity of integration | Lower | Higher |
| Cost | Smaller | Bigger |
| Resistance to obstacles | Depends on the interface | High |
6. Performance indicators
Modern precision optical encoders achieve a resolution of more than 20 bits per revolution (more than 1,000,000 positions). Magnetic sensors typically provide 12-16 bits, which is sufficient for most motors and drives. MTBF (Mean Time Between Failure) for quality components exceeds 100,000 hours under normal operating conditions.
7. Integration problems
The main technical difficulties in implementation are:
- Electromagnetic Interference (EMI): Requires use of shielded cables and proper grounding according to IEC 61800-5-2.
- Mechanical tolerances: Incorrect centering of the shaft leads to premature wear of the encoder bearings.
- Vibrations: Requires the selection of encoders with a higher resistance class (according to the requirements of ISO 16750).
8. Prospects until 2030
Trends point to the further integration of intelligent diagnostics directly into the sensor (Industry 4.0). The encoders will transmit not only the position, but also the temperature, the vibration state and the state of the bearings, which will allow the concept of predictive maintenance to be realized.
9. Links
- IEC 61800-5-2: Safety requirements for power drive systems.
- ISO 13849-1: Safety of machinery — Safety-related parts of control systems.
- Heidenhain Whitepaper: Principles of Encoder Accuracy and EnDat Interface.
To select components for your system, visit the UNITEC-D E-Catalog.
