As a sensing component in motion control and engineering machinery, displacement sensors play a crucial role in or influence measurement accuracy and system stability through their technology and performance characteristics. Based on differences in installation methods, certain key technical indicators, or measurement and control principles, commonly used displacement sensors mainly include: electronic rulers, optical encoders, magnetostrictive linear displacement sensors (magnetic rulers, hereinafter the same), and draw-wire displacement sensors. This article provides a simple explanation and comparison of the principles, characteristics, and applicable ranges of these four types of sensors from the perspectives of application and selection, serving as a beginner's reference.
I. Working Principle and Main Characteristics
II. Main Applications and Features
1.0 electronic ruler
1.1 Advantages and features: Electronic rulers are relatively inexpensive, and their low-temperature characteristics, low-torque operation, and suitability for high-speed applications make them widely used in injection molding machines, woodworking machinery, textile machinery, printing, spraying, machine tools, robots, and many other fields.
1.2 Limitations: Mechanical contact measurement methods suffer from severe wear and tear, resulting in a slightly shorter lifespan; they also have high requirements for power supply, lower anti-interference or reliability, and are not resistant to harsh application environments.
2.0 grating ruler
2.1 Advantages and characteristics: The grating ruler has good environmental adaptability, is wear-free, impact-resistant, vibration-resistant, and resistant to magnetic field interference, and has an extremely long service life; it also has good measurement accuracy and stability, and is widely used in modern automatic control systems, such as machine tool processing and measuring instruments.
2.2 Limitations: The price is relatively high, and the requirements for installation, debugging, maintenance, and working environment are relatively high.
3.0 Magnetic Ruler (Magnetostrictive Linear Displacement Sensor)
3.1 Advantages and Features: This type of sensor can withstand extremely harsh industrial environments, such as those susceptible to oil stains, solutions, dust, or other contaminants, without posing a problem. Furthermore, the sensor is more resistant to high temperatures, high pressures, and high vibrations. It is widely used in specialized industries such as metallurgy, petroleum, petrochemicals, water conservancy, and wastewater treatment; it is particularly suitable for applications involving cylinder hydraulics or liquid level detection.
3.2 Limitations: Compared to other sensors, its price is relatively high. Furthermore, the theories behind its detection and control are quite advanced and complex.
4.0 Cable Displacement Sensor (Cable Encoder)
4.1 Advantages and Features: The draw-wire encoder utilizes a hub structure to convert linear displacement into rotational angular displacement. By leveraging the mature technology and processes of angular displacement encoders, it ensures high precision in measurement accuracy and stability. Its ease of installation, compact structure, and lack of need for debugging make it a promising candidate for applications in industrial automation, engineering machinery, and other measurement and control fields. Due to its high cost-effectiveness, it can directly replace electronic rulers and optical scales in many applications.
4.2 Limitations: It is mainly limited by the constancy of the mainspring and the service life of the wire rope (such as wear and breakage). Especially in long-distance applications, it is difficult to adapt to the effects of vibration and impact, and the measurement accuracy will decrease.
