Introduction
Optical encoders are critical components in motion control systems, especially in conditions of high accuracy and reliability, which are characteristic of production in Ukraine. They are used to measure position, velocity, and acceleration, enabling precise control of industrial equipment. Choosing between incremental and absolute encoders, as well as determining resolution and accuracy, is an important step in the design of motion systems that affects long-term reliability and production efficiency.
Fundamental principles
Optical encoders work on the basis of measuring the light flux passing through the encoding disc or tape. They consist of an LED, a phototransistor, and an encoding disk that has slots and obstacles. According to the location of the light stream, signals are generated that are used to determine position or speed.
Incremental encoders output signals that correspond to a change in position, but do not retain position after power off. Absolute encoders, on the other hand, store information about the position even when there is no power. This makes them suitable for use in systems where the lack of power can cause critical consequences.
Technical parameters and standards
Optical encoders must conform to established standards to ensure their use in an industrial environment. The most important standards include:
- ISO 281: Establishes accuracy and angle change requirements in control systems.
- IEC 60947-2: Sets requirements for electrical devices, including encoders.
- DSTU 3016: Establishes requirements for electromagnetic compatibility in Ukraine.
- EN 50155: Establishes requirements for industrial electronic devices.
It is also important to meet the requirements of CE and UkrSEPRO certification, which ensure that products meet the requirements of industry standards.
Selection and calculation
The choice of encoder depends on the specific requirements of the system. Below is an example of calculating resolution and accuracy.
| Parameter | Incremental encoder | Absolute encoder |
|---|---|---|
| Resolution | 5000 lines/revolution | 10000 lines/revolution |
| Accuracy | ±0.1% (ISO 281) | ±0.05% (ISO 281) |
| Working temperature | -25°C to +85°C | -25°C to +85°C |
| Humidity | 5%–95% RH | 5%–95% RH |
| Average uptime | 50,000 hours | 75,000 hours |
The formula is used to calculate the required resolution:
Resolution = 1 / (Minimum distance between moving particles) Encoder selection must meet system requirements and meet standards to ensure reliability.
Installation and debugging rules
Correct installation and adjustment of the encoder determine its performance and durability. Here are the key recommendations:
- Mount the encoder on a clean, flat surface to ensure an accurate measurement base.
- Use special adapters to ensure compliance with the standards.
- Check measuring ranges before use.
- Perform test checks for signal stability and accuracy.
- Use special tools for setting and measuring.
It is important to follow the manufacturer's recommendations to ensure high quality and reliability.
Failure Modes and Cause Analysis
Optical encoders can fail for various reasons. Below are the most common failure modes and their visual indicators:
| Crash mod | Reasons | Visual indicators |
|---|---|---|
| Change in solvability | Disc or tape wear | Changing the signal amplitude |
| Signal failure | Dirty or damaged disc | No signal at all |
| Instability | Electrical noise or unstable power supply | Deviation from the mean value |
It is important to regularly check encoders for noise, wear or damage to ensure performance.
Service forecasting and condition measurement
Maintenance prediction and condition measurement is a key element in increasing the reliability of motion systems. The following methods are used:
- Temperature measurement: Allows detection of thermal abnormalities that may indicate damage.
- Vibration measurement: Detects damage in mechanical components.
- Measurement of electric current: Enables detection of malfunctions in electronic components.
Use measuring devices to regularly check encoders and detect possible deviations.
Comparison table
Below is a comparison table of three alternative types of optical encoders:
| type | Resolution | Accuracy | Average uptime | Price |
|---|---|---|---|---|
| Incremental | 5000 lines/revolution | ±0.1% | 50,000 hours | €120 |
| Absolute | 10,000 lines/revolution | ±0.05% | 75,000 hours | €200 |
| Garbage | 20,000 lines/revolution | ±0.02% | 100,000 hours | €350 |
Encoder selection should take into account specific system requirements and budget.
Conclusion
Optical encoders are critical components for motion control systems used in industrial manufacturing. The choice between incremental and absolute encoders, as well as the determination of resolution and accuracy, must meet system requirements and standards. For reliable and efficient use, you can turn to UNITEC-D GmbH, which provides reliable and certified components that meet the requirements of industrial production.
Sources
- ISO 281: Accuracy of control systems
- IEC 60947-2: Requirements for electrical devices
- DSTU 3016: Electromagnetic compatibility
- EN 50155: Industrial electronic devices
- UkrSEPRO: Certification in Ukraine
