Author: FLUX

Capacitive encoders and inductive encoders are two common non-contact encoder technologies. Each has its strengths and ideal use cases, however, when it comes to harsh environments inductive encoders are the preferred choice. In this article, we look at the key differences between these two encoder types, highlighting their benefits and trade-offs. If you’re an engineer trying to decide which technology is best for your application, this short article is for you. 

Capacitive Encoders

A capacitive encoder determines position by sensing changes in the rotor’s electrical permeability. These variations alter the capacitance of the stator’s sensor structure, generating position signals. Capacitive encoders utilize high-frequency signals to detect changes in the rotor’s permittivity while typically operating with low power consumption.  A benefit of capacitive encoders is that the capacitive principle allows for high-resolution measurement. These encoders can also be lightweight and compact which makes them suitable for some robotics, semiconductor and other precision applications.

Despite these advantages, capacitive encoders come with limitations that can make them unsuitable for certain environments. One primary drawback is sensitivity to contaminants. Since capacitive encoders rely on the interaction of electric fields, the presence of dust, moisture, or oil can interfere with operation, leading to accuracy degradation or failure.

Capacitive encoders are not sensitive to magnetic fields, as they do not rely on magnetic principles for operation. While they can be affected by electromagnetic interference (EMI) in industrial environments—such as near motors, drives, or RF-emitting equipment—this can be mitigated by designing them to operate at sufficiently high frequencies. When properly engineered, capacitive encoders can achieve immunity to external electromagnetic disturbances.  

Inductive Encoders

An inductive encoder is a position sensor that operates based on the principles of electromagnetic induction. It determines position, speed, and direction by detecting changes in the electromagnetic field. The rotor features a patterned structure made of materials that influence induction in the stator’s sensor. These materials can either increase induction through permeability, decrease it via eddy currents, or both simultaneously. These variations in electromagnetic induction generate position signals, which are then processed and converted into precise positional data.

Compared to capacitive encoders, inductive encoders offer greater flexibility in rotor material selection, allowing materials with different coefficients of thermal expansion (CTE). This enables the use of the same material as the machine it is integrated into, ensuring excellent thermal compatibility. As a result, inductive encoders provide outstanding accuracy and mechanical stability, even under extreme temperature variations and thermal cycles. Inductive encoders offer strong resistance to environmental contaminants, electromagnetic interference, and mechanical wear. These characteristics make them highly suited for demanding applications in industrial automation, aerospace, and defense sectors, where durability and long-term reliability are essential.

Advantages of inductive encoders include:

1. Exceptional Durability in Harsh Environments – Inductive encoders excel in applications where exposure to dust, moisture or grease is common
2. Resistance to EMI & Noise – Inductive encoders are inherently resistant to electromagnetic interference, making them ideal for environments with high electromagnetic  noise, such as industrial machinery and aerospace applications.
3. Temperature Resilience – Inductive encoders maintain stability across a wide range of temperatures, from freezing cold to extreme heat, without special protection against humidity ensuring consistent performance in demanding applications.
4. Mechanical Robustness – Inductive encoders are very resilient to mechanical shock and vibrations.

In industries where accuracy is important, choosing the right encoders is essential. Among the options, inductive encoders stand out for their mix of accuracy, durability, and versatility. This article looks at the main benefits of inductive encoders and why they are a great choice for precision systems.

What Are Inductive Encoders?

Inductive encoders work using electromagnetic induction. They have a transmitter and receiver coil system that detects the position of a moving part, usually made of a conductive material. Unlike optical encoders that use light, inductive encoders detect changes in inductance caused by movement. This gives them a natural advantage in tough environments and in applications needing high precision.

Benefits of Inductive Encoders

1. High Accuracy and Resolution

Inductive encoders provide very precise position feedback, often down to sub-micron levels. This makes them perfect for tasks that require fine control, such as robotic arms, machine tools, or semiconductor manufacturing. Advanced signal processing helps reduce errors and ensures consistent results.

2. Reliable in Tough Environments

A key feature of inductive encoders is their ability to work well in harsh conditions. The technology can resist:

• Dust, dirt, and oil
• Moisture and humidity
• Vibrations and shocks
• Electromagnetic interference (EMI)

This makes them ideal for industrial environments or outdoor use, where conditions can be challenging.

3. Compact and Lightweight

Inductive encoders are often small and light, ensuring they’re ideal for applications where space and weight are limited. For example, in medical devices or drones, their compact size ensures precise operation without adding bulk.

4. Durable and Long-Lasting

With no moving parts or fragile components, inductive encoders are less likely to wear out. This means they last longer and need less maintenance, which is especially useful in systems where downtime is expensive.

5. Cost-Effective Over Time

Although inductive encoders may cost more upfront than some other types, their durability and low maintenance makes them cost-effective in the long term. This makes them a smart investment for systems that require high performance and reliability.

6. Adaptable for Different Uses

Inductive encoders can be customised for many applications. From linear to rotary motion and from large industrial systems to small precision devices, they can handle a wide range of needs. They can also be designed for specific measurement ranges and resolutions, ensuring they work well for unique tasks.

Applications of Inductive Encoders

Thanks to their versatility, inductive encoders are used in many industries, such as:

• Robotics: For precise joint movements and tool positioning.
• Aerospace: For reliable position feedback in flight control systems.
• Medical Devices: For accurate positioning in surgical robots and imaging systems.
• Industrial Automation: For robust feedback in manufacturing and assembly lines.
• Automotive: For advanced driver-assistance systems (ADAS) and electric vehicle (EV) components.

Warehouse robots require encoders to provide precise feedback on position, velocity, and direction. Whether you’re designing an autonomous mobile robot (AMR), a robotic arm, or a conveyor system, selecting the right encoder is essential to ensuring your applications performance is perfect.

Here are key considerations for choosing encoders in warehouse robots:

1. Accuracy and Resolution
   Warehouse robots often operate in dynamic and cluttered environments. High-resolution encoders ensure precise movements, important for tasks like pallet stacking or navigating narrow aisles. For these applications, rotary encoders provide high resolution for accurate tracking of velocity and position. Angle encoders are ideal when very precise rotational measurements are needed.
   
   
2. Environmental Durability
   Encoders must withstand the rigors of warehouse environments, including dust, temperature fluctuations, and vibrations. Look for encoders with IP ratings (e.g., IP65 or higher) and robust housing to ensure long-term reliability. Inductive encoders are particularly well-suited for environments with dust or vibrations, as they offer non-contact measurement and are less likely to be affected by harsh conditions.
   
   
3. Form Factor and Mounting
   Space is often limited in compact robots. Opt for encoders with a small form factor that integrate seamlessly with your motors or actuators. Shaft-mounted or through-bore designs can simplify installation. Rotary encoders are widely used for compact applications due to their flexible mounting options. Inductive encoders also tend to have small form factors, making them ideal for space-constrained environments.
   
   
4. Communication Protocols
   Warehouse robots rely on real-time data. Choose encoders compatible with your system’s communication protocols, such as RS-485, CANopen, or EtherCAT, to ensure seamless integration and data transfer.
   
   
5. Power and Connectivity
   Low-power encoders can help conserve battery life in mobile robots. Inductive encoders tend to be energy-efficient due to their non-contact design. Rotary encoders are available in both low-power and wireless options to suit various mobile robot needs.
   
   
6. Cost-Performance Balance
   While high-end encoders offer excellent features, consider your application’s specific needs to avoid overengineering. For example, a sorting robot may not require the same level of precision as a robotic arm handling fragile items.

Encoders are essential for underwater systems, providing precise motion control and feedback for equipment like underwater robots, ROVs, and marine monitoring tools. To perform well in these challenging environments, encoders must meet specific criteria. Here’s what to consider when selecting encoders for underwater use:

1. Waterproofing and Sealing

Encoders need strong waterproofing to handle extended exposure to water, including corrosive saltwater. Look for IP67 ratings and features like O-rings or epoxy coatings to ensure protection from leaks and damage.

2. Pressure Resistance

Encoders must withstand high pressures at greater depths. Durable materials like stainless steel or titanium are ideal for maintaining functionality and resisting deformation in extreme conditions. Check the encoder’s depth rating to match your application needs.

3. Corrosion Resistance

Saltwater accelerates corrosion, so encoders should use marine-grade materials or protective coatings. Options like stainless steel or anodized aluminum help ensure long-term durability. Low galvanic potential materials also reduce corrosion risks when used with other components.

4. Low Visibility Performance

Underwater environments often have poor visibility. Magnetic encoders, which use magnetic fields instead of light, are better suited for these conditions compared to optical encoders, which may struggle in murky or dark water.

5. Shock and Vibration Durability

Underwater systems face constant shocks and vibrations from currents, impacts, and machinery movement. Encoders should have reinforced housings and damping systems to maintain accuracy and resist mechanical stress.

6. Temperature Tolerance

Temperature changes underwater can range from freezing depths to warmer surface levels. Encoders should be rated for your temperature range and provide stable performance even with fluctuations.

7. Compact Size and Lightweight Design

Space and weight are often limited in underwater systems. Compact, lightweight encoders are ideal but must still deliver robust performance and durability.

8. Signal and Cable Reliability

Underwater signal transmission can face interference and attenuation. Encoders should have waterproof, shielded cables and connectors designed specifically for underwater use to ensure reliable communication.

9. Energy Efficiency

Many underwater systems operate on limited power, like batteries. Low-power encoders can help extend operational time and reduce the need for frequent recharges.

10. Easy Integration and Maintenance

Encoders should be easy to integrate into your existing system and require minimal maintenance. Modular designs or quick-disconnect systems make replacements faster and reduce downtime.

Final Thoughts

The right encoder for underwater applications must be waterproof, durable, and energy-efficient, while providing reliable performance under pressure. By carefully evaluating your specific needs, you can choose an encoder that ensures long-term success. Partnering with experts in underwater encoder technology can provide additional insights and tailored solutions.

Braunau am Inn, Austria – November 28, 2024 – FLUX GmbH (FLUX), a high-precision encoder company, has today announced the launch of a new 150mm size variant to its GMI Rotary Encoder product range.

GMI Rotary Encoders use FLUX’s patented Giant Magneto Impedance (GMI®) technology for hysteresis-free, absolute performance combined with robustness and large mounting tolerances. GMI Rotary Encoders offer high accuracy, repeatability, and resolution, featuring IP67-rated aluminum or steel housings for harsh environments, along with no hysteresis and real-time position update rates.

GMI Rotary Encoder characteristics:

• Compact & hollow shaft
• High accuracy & resolution
• Robust, 1P67 available
• Wide mounting tolerance
• Plug-n-play: no field calibration
• Extended temperature range

GMI Rotary Encoder applications:

• Cobots & robotic joints
• UAV / drones
• Gimbals
• Medical robots
• Torque motors
• Industrial

“We are pleased to further expand our GMI-ROT product line with more sizes,” said Paul Tutzu, Managing Director & Founder of FLUX GmbH “Depending on customer requirements, we have GMI and inductive technology ranges both available in thousands of configurations as standard with options for customisation.”

About FLUX GmbH FLUX designs and manufactures high-performance encoders for precise position and velocity feedback within closed loop motion control systems. FLUX encoders use proven Inductive and GMI® technologies ensuring maximum precision and reliability for your application. Visit www.flux.gmbh to learn more and follow us on LinkedIn.

Braunau am Inn, Austria – October 24, 2024 – FLUX GmbH (FLUX), a high-precision encoder company, has today announced it has expanded its partner network with Elimec Electromechanical Engineering Ltd. (Elimec), a specialist distributor of electro-mechanical systems and components to the Indian market.

FLUX designs and makes high-performance encoders for precision position and velocity feedback within closed loop motion control systems. FLUX encoders use proven Inductive and GMI® technologies ensuring maximum precision and reliability for your application.

This partnership follows FLUX’s recent launch of IND-MAX, a new range of precise and robust inductive rotary encoders for tough environments. IND-MAX encoders are available in thousands of configurations as standard in sizes ranging 125mm to 375mm outer diameter.

“We are proud to represent FLUX and expand its presence in the Indian market,” said Karthikeyan Anandan, Sales Manager India of Elimec. “The unique benefits of the new IND-MAX product line in terms of high-reliability, precision measurement in harsh environments is especially exciting for us.”

“FLUX encoders are increasingly used as the critical component in incredible machines including underwater robotic vehicles, exoskeletons, satellites and spacecraft,” said Paul Tutzu, Founder & CEO of FLUX. “We look forward to working closely with the Elimec team to support OEMs in the fast-growing and innovation rich Indian market.”

About FLUX GmbH

FLUX designs and manufactures high-performance encoders for precise position and velocity feedback within closed loop motion control systems. FLUX encoders use proven Inductive and GMI® technologies ensuring maximum precision and reliability for your application. Visit www.flux.gmbh to learn more and follow us on LinkedIn.

Braunau am Inn, Austria – October 1, 2024 – FLUX GmbH (FLUX), a high-precision encoder company, has today announced the launch of IND-MAX, a new range of precise and robust inductive rotary encoders for tough environments.

IND-MAX encoders are available in six sizes ranging from 125mm to 375mm outer diameter, offer a compact low profile form factor with large bore and up to 23 bits resolution. Robust housings are used throughout to ensure reliable operation even under high-shock and vibration, with IP67 rated versions also provided.

Attributes of IND-MAX include:

• High-reliability inductive technology
• True absolute position measurement
• Flat with a large through-hole
• Simple installation: plug & play with no calibration
• Wide operating and mounting tolerances
• Immune to magnetic and electromagnetic disturbance, insensitive to foreign matter

Visit https://flux.gmbh/products/ind-max-encoder/ or download the Datasheet to learn more.

The new IND-MAX product line is ideally suited to extreme environment applications on land, sea and air. Unlike other technologies such as optical and capacitive which can prove unreliable in these conditions, you can rely on FLUX inductive encoders to not let you down.

“We have been successfully providing customer-specific versions of IND-MAX into mission-critical applications for several years,” said Paul Tutzu, Managing Director & Founder of FLUX GmbH. “We are excited to now make this offering available to a wider audience with thousands of options available as standard on short lead-times.”

IND-MAX compliments FLUX’s other encoder product lines which includes the lightweight and compact IND-ROT unpackaged inductive encoders, and two product ranges based on the company’s patented GMI technology (Giant Magneto Impedance).

Visit https://flux.gmbh/products/ind-max-encoder/ or download the Datasheet to learn more.

3 Considerations When Selecting an Encoder for UAV’s

Unmanned Aerial Vehicles (UAVs) have revolutionised industries from agriculture to defence, thanks to their ability to perform complex tasks autonomously. A critical component in ensuring precise and reliable operation of UAVs is the encoder, a device that provides accurate feedback on the position, speed, and movement of various mechanical parts. Selecting the right encoder for a UAV involves understanding the specific requirements of the application and the environmental conditions in which the UAV will operate.

1.            Understanding the Application Requirements

When selecting an encoder for a UAV, it is essential to first define the application requirements. UAVs are used in a variety of tasks, from surveillance and mapping to cargo delivery and search-and-rescue missions. The specific role of the UAV will determine the type and performance characteristics needed for the encoder. Key factors to consider include:

• Type of Motion: The UAV may require encoders to provide feedback for rotary motion (such as the rotation of propellers or gimbals) or linear motion (such as adjusting wing flaps or landing gear). Identifying the type of motion is crucial in selecting the appropriate encoder.
• Precision and Accuracy Needs: The level of precision required by the UAV is determined by its application. For example, a UAV used in agriculture for precise spraying requires highly accurate position feedback to ensure correct coverage, while one used for general surveillance may have less stringent accuracy requirements. Encoders with high resolution and minimal error rates are preferred for applications needing fine control.
• Size and Weight Constraints: UAVs have strict size and weight limitations to optimize flight time and performance. The encoder must be compact and lightweight, minimizing its impact on the UAV’s overall weight budget while still delivering the required functionality.

2.            Environmental Considerations

UAVs are often exposed to a variety of environmental conditions, from extreme temperatures to high levels of dust or moisture. Selecting an encoder that can withstand these conditions is crucial for ensuring reliable operation. Key considerations include:

• Temperature Range: UAVs may be exposed to wide temperature variations, especially in high-altitude flights or extreme climates. An encoder must be able to operate within the expected temperature range without losing accuracy or functionality.
• Protection Against Contaminants: Dust, dirt, moisture, and other contaminants can impact encoder performance. Encoders with appropriate ingress protection (IP) ratings are better suited for outdoor or industrial applications, ensuring reliable operation in various environments.

3.            Integration and Compatibility

When selecting an encoder for a UAV, it is also essential to consider its compatibility with the UAV’s existing systems and components. Factors such as communication protocols, power requirements, and physical size should align with the UAV’s design and control systems. Easy integration with the UAV’s flight controller or other components can reduce complexity and enhance overall system reliability.

Learn more about FLUX INDUCTIVE Rotary Encoders.