Magnetic encoders and magnetic position sensors serve as crucial pillars in the development of robotics and automation technologies. They play an indispensable role in precise control, real-time feedback, and system optimization. With the rapid advancement of Industry 4.0 and smart manufacturing, the demand for motion accuracy, response speed, and environmental adaptability in robots and automation equipment continues to rise. Magnetic encoders and magnetic position sensors, with their high resolution, contactless measurement, and strong anti-interference capabilities, have become core technologies for achieving these applications. This article will explore the applications of these two key sensors in robotics and automation technologies, as well as the related solutions from Melexis.
Magnetic encoders provide real-time feedback for high-precision control
As the application scope of robotics and automation solutions continues to expand from specialized professional fields to more everyday application scenarios, the demand for encoders that can provide precise and cost-effective motion feedback in these systems is also increasing. For ensuring the accurate operation and safety performance of motor-driven applications such as robotic arms, automated packaging machines, and industrial weaving machines, the feedback mechanism of magnetic encoders is crucial.
Magnetic encoders play a key role in robotics and automation by precisely detecting the speed, position, and direction of moving components, providing real-time feedback to achieve high-precision control. Their primary function is motion control feedback, measuring motor speed and position while transmitting data to the controller to enable accurate motion control. In multi-axis motion systems, magnetic encoders ensure synchronized movement between axes, preventing error accumulation.
Magnetic encoders can be paired with servo motors or stepper motors to provide closed-loop control signals, optimizing system performance and reducing energy consumption. By continuously monitoring speed and position in real time, these encoders help detect anomalies, prevent equipment overload or operational instability, and execute fault detection and protection functions.
With their high resolution, low latency, and high reliability, magnetic encoders have become indispensable components in robotics and automation systems. Their value is especially evident in applications that require rapid response and high-precision control.
Magnetic encoder with outstanding stray field immunity
The Triaxis® MLX90382, launched by Melexis, is a compact absolute magnetic encoder chip with exceptional performance features. It boasts outstanding resistance to stray field interference, supporting both on-axis and off-axis precise sensing while enabling seamless integration with miniature motors. This encoder offers a resolution of up to 14 bits, providing absolute angular position information with a differential output mode. It supports speeds of up to 200k e-RPM, features on-chip integrated signal processing units for zero-latency response, and utilizes Triaxis® Hall technology, ensuring flexible for mounting in actual applications.
The MLX90382 is a fully functional monolithic magnetic position sensor, integrating an advanced Triaxis® Hall magnetic front-end, a high-performance analog-to-digital converter, and digital processing hardware units specifically designed for high-speed signal processing and conditioning, along with multiple different types of output drivers.
The MLX90382 demonstrates outstanding 360° stray magnetic field immunity (up to 4 kA/m) and accurately senses the three components of magnetic flux density (Bx, By, and Bz) applied to the chip, while being highly sensitive to differential magnetic fields along the z-axis. Through programming, users can flexibly select any axis to determine the angle. This design, combined with an ingenious magnetic layout, enables the MLX90382 to precisely compute both absolute and incremental positions of any rotating magnet.
The MLX90382 offers five versatile output modes, including industry-standard single-ended and differential ABI interfaces for incremental angular output, single-ended and differential UVW signal emulation designed for BLDC motors, as well as PWM and configurable SPI and SSI interfaces, supporting functional safety requirements. Additionally, the SPI protocol features multi-slave synchronized readout, further enhancing system flexibility and efficiency.
The MLX90382 effectively addresses common assembly challenges in complex motor drive applications, supporting both on-axis and off-axis mounting flexibility, providing greater convenience for users. This feature enables the chip to support hollow shaft applications, allowing wiring looms or other components to pass through the shaft without interfering with encoder feedback, thereby reducing design complexity and driving technological innovation.
The MLX90382 supports a wide operating range, functioning in temperatures from -40°C to 150°C, and is compatible with both 5V and 3.3V applications. It features programmable linear transfer characteristics, supports up to 16 programmable points, and complies with SIL-2 safety integrity standards. It is housed in a RoHS-compliant, single-mode 4 x 4 mm² QFN-24 package. Both variants are AEC-Q100 (Grade 0) certified, ensuring product reliability.
With its 14-bit high resolution, differential output mode, and wide speed range of up to 200k e-RPM, the MLX90382 is an ideal choice for industrial automation, robotics, and electric transportation solutions. It is well-suited for applications such as robotic joints, weaving machine motors, electric vehicle motors, and industrial automation. To accelerate development, Melexis also offers an evaluation board (EVB90382) and a comprehensive development kit (DVK90382).
The MLX90382 evaluation board, EVB90382, provides a simple way to connect the MLX90382 Triaxis® magnetic sensor to a microcontroller or measurement device. It allows pre-programming of the MLX90382 IC for easy connection and evaluation, helping to shorten development time. The EVB90382 includes an MLX90382 IC mounted in the middle of a 36mm x 48mm PCB. The board features machined pins for quick connection to the MLX90382 IC interface and includes necessary passive components to allow interfacing via analog output signals.
Magnetic position sensors for detecting object position, angle, or motion
In previous robotic design solutions, manufacturers often prioritized top-performance sensor chips while paying relatively less attention to cost considerations. However, as robotic applications continue to expand, manufacturers are increasingly focused on improving production efficiency while reducing costs. This has made them more cautious in selecting components to ensure economic and simple designs while maintaining high reliability and precise motion repeatability in robots.
Magnetic position sensors play a crucial role in robotics and automation by detecting changes in magnetic fields to determine an object's position, angle, or motion, providing high-precision feedback signals to the system.
Magnetic position sensors enable contactless detection, measuring changes in magnetic fields without physical contact, which reduces wear and maintenance requirements.
These sensors offer high-precision measurements of angular position, linear displacement, or rotational speed, meeting the requirements for precise control in robotics and automation systems. They also exhibit strong resistance to interference and are unaffected by environmental factors such as dust, moisture, and oil, making them well-suited for operation in harsh environments. Additionally, they are typically compact and energy-efficient, making them ideal for integration into space-constrained devices.
The advantages of magnetic position sensors include durability, stable performance, and adaptability to various environments, making them indispensable components in robotic and automation systems for motion control, positioning, and safety detection.
Magnetic position sensor with innovative magnet design and superior sensing capability
The MLX90384, introduced by Melexis, is a high-precision magnetic position sensor designed for robotic joints. This product employs Arcminaxis™ technology and is equipped with a magnet and software for calibration and system operation. It offers a resolution of up to 18 bits and is pitch-independent. A single integrated circuit is compatible with multiple magnet types, supports high-speed communication, and features a fast SPI interface.
The core advantage of the MLX90384 lies in its innovative magnet design and superior sensing capability. Unlike traditional multi-pole magnet sensor chips, the MLX90384 eliminates the strict requirement for precise matching between the magnet pole size and sensor chip. This feature enables the use of larger, more powerful magnets, thereby generating stronger output signals and supporting greater operating airgap. As a result, the same sensor chip can flexibly accommodate magnets of various sizes.
The MLX90384 integrates two position sensor chips, each featuring a Triaxis® Hall magnetic front-end, an analog-to-digital converter, dedicated high-speed signal conditioning hardware, and a high-speed 10MHz SPI interface. Both ICs are designed to sensitively detect two magnetic flux density components—one parallel to the chip plane and the other perpendicular to it.
The Arcminaxis™ MLX90384 Hall 18-bit angular encoder chip combines multi-axis sensing and vernier technology, utilizing a vernier-type magnet with two tracks (eight-pole and seven-pole pairs). The MLX90384 sensor chip measures the axial and tangential magnetic components of these two tracks, then transmits this information to a microcontroller. The microcontroller processes the received data to accurately calculate angular position, speed, and counted turn out information. Additionally, it supports precompiled software packages for calibration and system operation on microcontrollers (MCUs), providing a complete reference design for building encoder solutions.
The MLX90384 sensor features a large airgap magnet design (1.5mm nominal), with magnet placement tolerance of ±0.5mm, reducing the complexity and workload of robotic joint assembly. It operates at a 3.3V supply voltage, is packaged in a TSSOP-16 form factor, complies with RoHS standards, and functions within a temperature range of -20°C to 85°C. The MLX90384 sensor serves as an absolute rotary position sensor, high accuracy encoder, and robotic joint encoder, applicable in electric vehicles, industrial motors, and other fields.
The MLX90384 evaluation kit (EVK90384) is specifically designed to simplify the exploration of Arcminaxis technology. Fully aligned with the MLX90384 reference design, this kit ensures a quick project startup, enables precise implementation of the reference design, and offers a convenient connection and calibration process to significantly shorten development cycles. Melexis provides a comprehensive evaluation toolkit to streamline the assessment of Arcminaxis technology. The kit includes a fully functional tabletop demonstrator, which features an SPI master controller for seamless USB-PC connectivity and an intuitive graphical user interface (GUI) for calibrating and operating the MLX90384 demonstrator. The tabletop demonstrator has a detailed structure, integrating a magnet ring set, magnet holder, a sensor module, a base element, an SPI master controller, and specialized cables for connecting the sensor module to the SPI master controller, ensuring an efficient and convenient evaluation process.
Conclusion
Magnetic encoders and magnetic position sensors, as key technologies, are driving the robotics and automation fields toward higher control precision and efficiency. These sensors not only provide accurate position and speed feedback but also meet the modern industrial demands for high responsiveness and reliability. As artificial intelligence and machine learning continue to be integrated, the application scenarios for these sensors will expand even further, benefiting fields such as smart manufacturing, medical robotics, and unmanned systems. Melexis' magnetic encoders and magnetic position sensors offer exceptional technological advantages, enabling comprehensive advancements in intelligence and automation, thereby creating greater value for the industry.