On July 1, China's TMR magnetic sensor company Multi-Dimensional Technology released the TMR3111D magnetic rotary encoder integrated circuit. This product is designed for high-speed, high-precision rotary position detection in robotics, servo motors, and industrial motion control, and will be showcased at electronica China 2026.
The technical focus of the TMR3111D lies in integrating TMR magnetoresistive sensing, angle calculation, and digital signal processing into a single compact encoder chip. The core task of a rotary encoder is to convert the rotational angle of a motor shaft, robot joint, or actuator into a position feedback signal readable by the control system; in servo systems, this feedback signal directly enters the closed-loop control to correct speed, position, and torque output. The TMR3111D employs a non-contact magnetic detection method, calculating the angle by sensing changes in the magnetic field generated by the rotation of an external magnet, without requiring grating disks, mechanical contacts, or complex optical structures. This makes it suitable for robot joints and motor end structures where space is limited, vibration is prevalent, and assembly tolerances are difficult to control. The product supports both coaxial and off-axis magnetic configurations, meaning the magnet can be placed directly above the chip or in an offset structure to accommodate mechanical space design, providing greater structural margin for robot actuators, motor modules, and compact joints.
Interface configuration is a key aspect of the TMR3111D for motion control systems. The chip supports SPI, ABZ, PWM, and UVW outputs, simultaneously accommodating absolute angle feedback, incremental encoder feedback, and motor commutation control requirements.
The SPI interface is used for outputting absolute angle data, suitable for direct reading of rotor or joint position by the main control chip; the ABZ interface is used for incremental encoder systems, providing pulse feedback for traditional servo drives; the PWM output facilitates angle information transmission via duty cycle; the UVW and Z-phase outputs can be used for brushless motor commutation and zero-position reference. The ABZ incremental output of the TMR3111D can be programmed up to 4,096 PPR, with an internal angle data format of 23 bits, supporting a maximum rotational speed of 40,000 rpm, an operating voltage range of 3 V to 5 V, and packaged in a 3 × 3 × 0.75 mm DFN10L package. For high-dynamic servo systems, high-speed support and a small package are critical, as actuators often house motors, reducers, drive boards, bearings, wiring harnesses, and sensors simultaneously; the smaller the encoder size, the easier it is to integrate into a unified joint module.
Compared to Hall-effect encoders, the advantages of TMR technology are primarily in magnetic sensitivity and signal-to-noise ratio. Higher sensitivity allows the chip to obtain effective signals even in weak magnetic fields or with installation deviations, while a higher signal-to-noise ratio helps reduce angle jitter.
In robotics and servo motor applications, the stability of angle feedback directly impacts control accuracy. When robot joints operate under low-speed precision positioning, high-speed oscillation, frequent start-stop, and load variations, if the encoder exhibits noise, drift, or nonlinear errors, the controller will introduce these errors into the closed-loop regulation, leading to motor jitter, position deviation, response lag, or trajectory instability. The TMR3111D features built-in automatic gain compensation and nonlinear calibration functions, capable of correcting installation-related magnetic errors to improve batch assembly consistency. This design is crucial for mass production, as magnet position, air gap, axial deviation, and PCB assembly angle cannot be perfectly consistent across large batches of the same robot joint; chip-level compensation capabilities can reduce backend calibration and manual debugging workload.
The application directions for the TMR3111D focus on humanoid robots, quadruped robots, collaborative robots, industrial robot joints, servo motor systems, and precision motion control equipment. Humanoid and quadruped robots are particularly sensitive to joint position feedback; knee, hip, ankle, shoulder, elbow, and wrist actuators all require real-time knowledge of the current angle to achieve balance control, gait planning, torque distribution, and motion compensation. Industrial and collaborative robots place greater emphasis on repeat positioning accuracy, trajectory consistency, and long-term operational reliability. The TMR3111D offers high speed, non-contact operation, a small package, multiple interfaces, and automatic calibration capabilities, precisely aligning with the trend toward high integration, high dynamics, and high precision in robot actuators. For servo system manufacturers, this type of chip can be used in compact motor feedback, built-in joint module encoders, smart actuators, and high-end motion control boards, helping to simplify encoder structure and enhance system integration.
The technical significance of this product lies not in "adding another sensor model," but in the fact that magnetic rotary encoders are entering core robotic actuation components. As robot joints evolve from discrete combinations of motors, reducers, drives, and sensors toward integrated actuators, encoders must simultaneously meet requirements for small size, high speed, high precision, strong immunity, and ease of assembly. By integrating TMR sensing, digital angle output, automatic compensation, multiple interfaces, and high-speed rotation support into a single compact chip, the TMR3111D compresses position feedback functionality, reducing the structural complexity of robot joints and servo modules. What truly warrants attention going forward is the product's actual consistency under high temperature, vibration, long-term operation, batch assembly errors, and different magnetic circuit designs, as well as its adoption progress among customers in robot actuators, servo motors, and industrial motion control.