Author: FLUX

Legged robots are revolutionizing robotics with their agility and versatility, and one key technology enabling their advanced movement is high-performance encoder systems. This article explores the role of encoders in legged robots, defines a legged robot, discusses key considerations for selecting an encoder, and explains why inductive encoders are a highly effective option. 

Understanding Encoders for a Legged Robot

Encoders are devices that convert mechanical motion into an electrical signal, allowing it to be read by a control system. In the context of legged robots, encoders ensure that every step, rotation, and adjustment is accurately tracked. This real-time data information provides accurate control over the robot’s movements, ensuring balance and dynamic interaction with its environment. With the rapid advancement of robotics, choosing the right encoder is essential to achieve optimal legged robot performance.

What Is a Legged Robot?

A legged robot is an autonomous mobile machine engineered with articulated legs to enable dynamic, agile movement. Legged robots are designed to mimic the natural movement of animals and are built to traverse uneven terrain, climb obstacles, and execute complex maneuvers. These examples of versatility and mobility make legged robots highly valuable where precision and adaptability are essential. Designed to operate in challenging environments, legged robots integrate advanced control systems and robust encoder technology to ensure smooth, coordinated movement. 

Key Considerations for Choosing an Encoder for a Legged Robot

When selecting an encoder for a legged robot, there are several key performance considerations to help ensure reliable and precise operation in dynamic environments:

• Resolution and Accuracy: High precision is essential to track the subtle and rapid joint movements in legged robots. An encoder with high resolution ensures accurate position feedback, which is a crucial factor for balance and coordination.
  
• Robustness: Legged robots typically operate in unpredictable environments; therefore, a robust encoder must be able to tolerate vibrations, shocks, dust, and wide temperature variations without compromising performance.
  
• Mounting Tolerance and Working Range: Encoders with a large mounting tolerance and broad working range simplify integration and alignment.
  
• Size and Weight: Compact and lightweight encoder designs are important for maintaining the agility and efficiency of the legged robot, especially in mobile applications.
  

Understanding and applying these considerations can help designers and engineers select the right encoder to meet the technical demands of a legged robot and enhance its overall performance.

Selecting the Best Encoder for a Legged Robot

A legged robot requires precise, real-time feedback to maintain balance and adapt to dynamic environments. FLUX inductive encoders are engineered to meet these demands with exceptional accuracy, robustness, and ease of integration.

FLUX inductive rotary encoders are compact and ultra-lightweight, making them ideal for space-constrained legged robot joints. They deliver high-resolution absolute position data, ensuring reliable motion tracking for smooth, coordinated movement. Their frameless design allows for flexible installation with wide mounting tolerance, while immunity to magnetic and electromagnetic interference ensures stable performance.

For more extreme conditions, FLUX IND-MAX inductive angle encoders offer high-precision measurement and superior durability, pushing the boundaries of what’s possible for a legged robot in harsh operating scenarios.

With their advanced design and robust performance, FLUX inductive encoders are a top choice for engineers developing the next generation of legged robots.

Conclusion

Selecting the right encoder is essential for both the performance and precision of legged robots, as it can ensure smooth and coordinated movement. The high-precision performance, robustness, and wide mounting tolerance of FLUX inductive encoders highlight them as a highly effective option. These benefits make FLUX encoders ideal for demanding environments that require high accuracy and reliability, such as legged robot applications. FLUX inductive encoders can enable designers and engineers to ensure that their legged robots meet the challenges of real-world operation while pushing the boundaries of innovation.

Selecting the most suitable absolute encoder for your system is key to ensuring reliable performance in demanding applications and harsh conditions. This article explores what an absolute encoder is, reviews the different types of absolute encoders available, and explains why absolute inductive encoders offer a more reliable solution for tough environments.

What Is an Absolute Encoder?

An absolute encoder is a type of sensor that provides a unique digital output for angular position, allowing the position to be tracked with high accuracy even in the case of loss of power. Absolute encoders provide a different code for each possible angular position so that the system will be aware of its precise position at power-up without needing a reference or homing sequence. This feature makes absolute encoders ideal for applications requiring high precision, dependability, and continuous performance, such as robotics, automation industries, and CNC machinery. 

Absolute Encoder vs Incremental Encoder

In contrast to absolute encoders, which give a specific position reference for each angular position, incremental encoders only give relative position information. Incremental encoders monitor movement by creating pulses as the axis turns, and the position is calculated by counting these pulses from a known reference point. While incremental encoders are less complex, they require a homing sequence after power loss or system reset to determine the exact position. 

Therefore, they are not suitable for applications where position accuracy must be maintained and recovered instantaneously after a power disruption. However, incremental encoders remain widely used in situations where relative position and motion tracking are sufficient, such as in basic speed monitoring, rotary switches, and motion control systems in some instances.

Absolute Encoder Types 

Absolute encoders come in various technology types, each suited for different applications. The most common types are:

• Optical Encoders: Optical encoders use a light source, typically an LED, and a photodetector to read patterns on a rotating disk. Known for their high resolution and accuracy, these encoders are typically used in applications where precision is essential. However, they can be sensitive to dust and contaminants, which may impact their reliability in certain environments.
• Magnetic Encoders: Magnetic encoders rely on magnetic fields to detect position, a method that often results in lower accuracy and can be prone to interference from external magnetic sources. These limitations can significantly reduce their reliability, especially in demanding applications that require high precision or consistent performance in variable conditions.
• Capacitive Encoders: Capacitive encoders detect position by sensing changes in the electrical permeability of the rotor, which in turn affect the capacitance of the stator’s sensor. These encoders have high resolution and low power consumption with high-frequency signals. Capacitive encoders can be sensitive to contaminants like dust or water, which can affect performance. While immune to magnetic fields, they can be susceptible to electromagnetic interference (EMI), but this can be countered by design.
• Inductive Encoders: An inductive encoder uses electromagnetic induction to measure position. It detects changes in the electromagnetic field caused by a patterned rotor, generating signals that are processed into precise positional data. Inductive encoders are resistant to environmental contaminants, electromagnetic interference, and mechanical wear, making them ideal for demanding applications.
• GMI Encoders: GMI encoders use the Giant Magneto Impedance effect to detect positional changes based on the interaction of magnetic fields with specially treated sensor materials. Unlike incremental encoders, they provide a unique position value at every point, ensuring precise absolute position detection even after power loss. These encoders combine high resolution and exceptional angular accuracy with strong resistance to shock, vibration, and environmental contaminants. Their inherent immunity to magnetic interference and robust signal integrity make them ideal for applications requiring both the highest precision and durability in dynamic environments.
  

How do I Choose an Absolute Encoder?

Choosing the right absolute encoder is dependent on several factors. To ensure the right absolute encoder is selected, consider the following:

• Resolution & Accuracy: Determine the required precision for your application. Higher resolution encoders provide finer position feedback.
• Environmental Conditions: Assess exposure to dust, moisture, or extreme temperatures to help choose an encoder with the appropriate protection rating (e.g., IP65 or higher).
• Communication Protocol: Ensure compatibility with your system by selecting the right interface.
• Mounting & Form Factor: Choose an encoder that fits within your space constraints, whether it’s shaft, hollow shaft, or PCB-mounted.
• Durability & Lifespan: Consider the operating conditions and expected longevity.

Which Absolute Encoder Is Best for Tough Environments?

When it comes to choosing an encoder for harsh and demanding applications, absolute inductive encoders stand out. Their robust construction and reliable performance in adverse conditions make them the superior choice over other absolute encoder technologies. In environments where dust, moisture, vibration, and temperature extremes are prevalent, an absolute inductive encoder delivers consistent, accurate position feedback while minimizing maintenance and repair costs.

What is an Absolute Inductive Encoder?

An absolute inductive encoder operates on the principles of electromagnetic induction to determine position by detecting changes in the electromagnetic field. The rotor incorporates a patterned structure made of materials that affect induction within the stator’s sensor. These materials can enhance induction through permeability, reduce it via eddy currents, or influence both simultaneously. The resulting variations in electromagnetic induction generate position signals, which are then processed and converted into highly accurate positional data.

Absolute Inductive Encoder Advantages

Absolute inductive encoders offer a variety of advantages over other absolute encoder technologies:

1. Exceptional Durability in Harsh Environments: Absolute inductive encoders thrive in settings exposed to dust, moisture, and grease, making them an optimal choice for industrial and manufacturing applications.
2. High Contaminant Tolerance: Absolute inductive encoders remain unaffected by dust, dirt, grease, or moisture, ensuring optimal performance in challenging industrial conditions.
3. Superior EMI & Noise Immunity: Their inherent resistance to electromagnetic interference makes them ideal for environments with high EMI, such as factories with heavy machinery, aerospace systems, and medical equipment facilities.
4. Broad Temperature Resilience: Designed to operate reliably from freezing conditions to extreme heat, these encoders maintain stability without the need for extra humidity protection.
5. Mechanical Robustness: Built to withstand shock and vibrations, absolute inductive encoders ensure consistent performance even in applications subject to high mechanical stress.

Conclusion

In summary, while absolute encoders are crucial for accurate position tracking, only certain technology types are suitable for tough environment applications. Absolute inductive encoders are the preferred choice as they combine durability, reliability, and cost-effectiveness, ensuring optimal performance even under extreme conditions.

Inductive sensors are the leading technology for reliable sensing in harsh environments. Their robust design makes them ideal for industrial manufacturing, automation, and other demanding applications where extreme conditions challenge traditional sensing technologies. This guide explores how inductive sensors work, their key advantages, real-world applications, and the benefits they bring to various industries.

What is an Inductive Sensor?

An inductive sensor is a type of non-contact device that detects metal objects by generating an electromagnetic field. When a metal target enters this field, the sensor detects changes in inductance and converts them into an electrical signal. There are several types of inductive sensors, including simple proximity switches, variable inductance and variable reluctance sensors, synchros and resolvers, and more advanced technologies like rotary and linear variable differential transformers (RVDTs & LVDTs) and next-generation inductive encoders.

Inductive Sensor Applications

Inductive sensors are a proven technology for reliable performance in extreme conditions. Designed to operate without physical contact, these sensors are highly resistant to wear, temperature changes, moisture, vibration, and contaminants like dust and chemicals. 

Their durability makes them the go-to solution for safety-critical and high-reliability applications across a variety of industries. 

Heavy Industry & Manufacturing

• Robotic Arm Positioning – Provides precise movement feedback for automation
• CNC Machine Tool Position Sensing – Ensures accuracy in machining operations
• Conveyor System Alignment – Tracks position for automated material handling

Aerospace, Defense & UAVs

• Landing Gear Position Sensing – Ensures correct deployment and retraction of aircraft landing gear
• Flight Control Positioning – Tracks control surfaces such as flaps, rudders, and stabilizers
• Missile and Weapon System Alignment – Provides real-time position feedback for targeting systems
• UAV Navigation & Landing Systems – Detects position changes for autonomous takeoff and landing

Subsea & Underwater Robotics

• ROV & AUV Positioning – Tracks thruster and actuator movement for deep-sea operations
• Diver Propulsion Systems – Provides position feedback for underwater navigation
• Subsea Valve Position Sensing – Ensures safe operation of critical oil and gas infrastructure
• Sonar and Camera System Alignment – Maintains accurate positioning for underwater imaging

Medical Robotics & Devices

• Surgical Robot Position Sensing – Provides real-time feedback for robotic-assisted surgery
• MRI-Compatible Sensor Systems – Tracks movement in magnetic environments without interference
• Exoskeleton and Prosthetic Limb Positioning – Enhances mobility with precise motion detection
• Automated Medical Equipment – Ensures accurate positioning in drug delivery and diagnostic devices
  

Energy & Offshore Applications

• Wind Turbine Blade Position Monitoring – Optimizes efficiency and performance in renewable energy systems
• Oil & Gas Drilling Position Feedback – Tracks drill bit location for precision drilling
• Hydroelectric Dam Gate Position Sensing – Ensures accurate control of water flow
• Nuclear Reactor Valve Position Detection – Monitors critical components for safety compliance
  

Inductive Sensor Characteristics

When selecting an inductive sensor, it is important to consider the following key features:

• High Robustness: Built to withstand dust, moisture, and chemicals, making them perfect for tough industrial environments.
• Long Operating Life: As they do not have any contacting parts, they get less deteriorated and have a longer operating life.
• Fast Response Time: Their high-speed response towards metal objects makes them suitable for high-speed applications.
• Easy Installation: Their compact nature and toughness make them simple to install within any system.
• Environmental Immunity: They are not as vulnerable to temperature or lighting variation as other sensors.

Inductive Sensor Benefits

Inductive sensors offer a wide range of benefits, especially in harsh environments, making them the preferred choice over alternative position sensing technologies like optical encoders, capacitive encoders, and magnetic encoders. 

1. Superior Performance in Contaminated Environments

• Unlike optical encoders, which can fail due to dust, oil, or debris blocking the light path, inductive sensors remain fully operational in dirty, wet, or greasy environments.
• The same applies to capacitive encoders which rely on the interaction of electric fields. The presence of dust, moisture, or oil can interfere with operation, leading to accuracy degradation or failure.

2. Resistance to Extreme Temperatures

• Inductive sensors function reliably in high-temperature environments, making them ideal for applications in industrial automation, aerospace, and heavy machinery.
• Magnetic encoders can suffer from demagnetization at high temperatures, leading to performance degradation, while inductive sensors maintain accuracy.

3. Immunity to Magnetic Interference

• Unlike magnetic encoders, which can be disrupted by nearby electromagnetic fields (such as those from motors, transformers, or power lines), inductive sensors operate without interference.

4. High Shock and Vibration Resistance

• Inductive sensors can withstand extreme shock and vibration, unlike optical encoders, which contain fragile components such as glass discs or sensitive electrodes.

5. Reliable in Subsea and High-Pressure Environments

• Inductive sensors are ideal for subsea and high-pressure applications where other technologies fail. Optical and capacitive encoders cannot operate reliably in oil-filled housings, as their principles are disrupted by liquids.
• In contrast, FLUX’ inductive sensors function flawlessly in non-conductive fluids like oil, thanks to their sealed, contactless design. This makes them well-suited for ROVs, AUVs, offshore drilling, and other deep-sea systems.

6. Low Power Consumption

Inductive sensors are energy-efficient, consuming less power compared to some other technologies like magnetic encoders or optical encoders, which may require higher power for signal processing or illumination.

At FLUX GmbH, we believe that collaboration is key to pushing the boundaries of space technology and advancing space exploration. Last week, we had the privilege of welcoming Leonardo Space to our company, further reinforcing our commitment to pioneering advancements in space technology.

As we continue to innovate and collaborate, FLUX GmbH is excited about the potential projects on the horizon. With a skilled team of engineers, we are eager to tackle future challenges in space applications. Our expertise and passion empower us to redefine the future of space exploration.