Harnessing the potential of inductive encoders in robotics

The robotics industry continues to experience wider adoption across various sectors and company sizes, both in traditional and emerging industries. This is especially true for industrial robots, which are leveraged for their speed, power and durability. However, accuracy has become a key part of the equation for robotics and automated manufacturing applications.

Enter encoders. Encoders play a crucial role in robotics motion control by providing precise and accurate feedback on angle, position and speed. At a very high level, an encoder is an electronic device that measures the position and velocity of a rotating shaft or linear motion. It generates digital or analog signals to represent this information and keep track of how different parts of a robot move. This helps the robot know where it is and how it’s moving around.

But as with many solutions, not all encoders are created equal. Choosing the right encoder comes down to different factors and requirements.

Common challenges in robotics encoder selection 

Robotic solutions are held to the highest standards and must perform under increasingly growing demands like handling heavier loads, quicker speeds, higher throughput and more dynamic performance. No matter the specific applications, careful encoder selection for robotics is crucial to address common challenges and maximize efficiency.

Ensuring accuracy and resolution

When it comes to robot design, it can be difficult to find high positioning accuracy at the tool center point. However, rotary encoders can help achieve high repeatable accuracy by providing motor feedback and measuring axis position and speed.

Withstand challenging conditions

Robotics often operate in challenging environments, including high temperatures, humidity, vibration, and exposure to dust or other contaminants, putting extreme demands on encoders. When selecting an encoder, it’s important to choose an option that can withstand these conditions without compromising performance or reliability. Rotary encoders are ideal for industrial applications due to their compact and rugged design.

Seamless integration

Did you know an estimated 70 percent of production costs are due to design decisions? When selecting a rotary encoder (or any encoder), be sure to evaluate its effect on the robot assembly process and overall existing operation. Consider details such as size, shape, structure and compatibility with the robot’s design for a seamless installation and integration.

The role of inductive encoders in robotic applications

Rotary/angle absolute encoders are the most common versions used  in robotics. These encoders can be optical, magnetic or inductive depending on the application requirements. For this article, we’re going to zoom in on inductive encoders in robotics.

Inductive encoders are used for general automation, medical applications and robotics, to name a few. They have charged coils that are passed over by a passive disc, modulating what charges the sensor receives.

Think of an inductive encoder as the Goldilocks solution between optical and magnetic encoders. While they don’t offer the extreme accuracy of optical encoders, they do provide high control quality and system accuracy. Plus, inductive encoders can hold up well in harsh environments similar to magnetic encoders, able to resist high-end vibration dynamics, magnetic fields and contaminants.

Why robot designers choose inductive encoders

To ensure that robots achieve high positioning accuracy, robot designers must account for several factors including method of encoder operation, tolerances, assembly, installation space and so on. Inductive encoders can ease accuracy concerns due to the way they measure the angular position of the joint directly at its axis, meaning mechanical inaccuracies in the joint no longer play a role.

Inductive encoders are also complete components, which makes it easy to implement Functional Safety standards up to SIL 3 / PL e. For example, this is particularly important for collaborative robots (cobots) so the manufacturer can guarantee the required certification for their component. 

5 benefits of using inductive encoders in robotic production

1) Small footprint  – The compact size of inductive rotary encoders is ideal for environments where space is limited or when a secondary encoder is needed.

 2) Simplified assembly – Inductive encoders require only three parts, which allows for a simpler setup, and the rotors require no specific orientation on the shaft. There is also the option for press-fitting, a readily automatable assembly method.

3) Reliable data and maintenance – HEIDENHAIN inductive encoders deliver consistent, precise and extensive status data through our proven EnDat interface. This not only results in superior condition monitoring and diagnostics, but it is also necessary for predictive maintenance.

4) Electronic ID label – In addition, absolute rotary encoders from HEIDENHAIN feature an electronic ID label accessible through the EnDat interface. This provides data on the encoder’s resolution, ID number, serial number, and more for enhanced tracking and visibility.

5) Enhance process stability – Inductive encoders from HEIDENHAIN enable electronic mounting diagnostics which can immediately identify proper installation and performance. It also can help ensure the quality of the final product to enhance process stability.

Are gaps between elements within the permissible tolerances? Are there potential improvements to the manufacturing process? Are there inaccuracies between the rotors and the scanning unit? The more you know, the better you can optimize.

Selection criteria for choosing the right robotic inductive encoder

Like evaluating anything in business or life, it’s important to gain alignment on the need. The best place to start is by identifying the primary key elements required for your project, like what accuracy levels you want to achieve, what mechanical space you have, what environment you will be operating in and your desired budget range. 

From there, you can begin layering in additional elements like safety, flexibility, feature requirements, etc. With this information, our industry experts can help guide you to the best solution to make your project successful and add value to your next robot design.

At HEIDENHAIN, we offer a full line of linear, angle and rotary encoders, and are one of the few companies in the world to offer inductive encoders in robotics. Contact us today to learn more about how we can help move you forward with precision.

Written by: Stuart Graham—Business Development Specialist

Stuart Graham is a seasoned Business Development Specialist at HEIDENHAIN CORPORATION, where he has worked for over a decade. His expertise and passion lie in promoting advanced encoder technology, which is integral to the fields of robotics, medical equipment, metrology and general automation. 

Written by: Jonathan Dougherty—Business Development Manager

Jonathan Dougherty is the Business Development Manager for HEIDENHAIN CORPORATION. He is a graduate of the University of Illinois with a Bachelor of Science in Industrial Controls and Systems Engineering. He has a decade of experience with encoders and motion control topics and has taken an active role in promoting multi-dimensional encoder solutions, functional safety and encoders for robotic joints. He is a member of IEEE and the Association for Advancing Automation (A3) and has presented at conferences nationally on these topics.