TDK InvenSense正与机器人厂商开发人形机器人关节用低成本磁传感器（TMR/霍尔），部分关节或替代编码器

ense is developing low-cost magnetic sensor technology for humanoid robot joints. The solution uses a simple configuration consisting of one magnet and one sensor to measure joint angles, potentially replacing encoders in certain joints, including fingers.
TDK Vice President Jung Do-hyung said at THE ELEC's "Semiconductors Powering Humanoids" conference, held at COEX in Seoul on Oct. 16, that the company is working with robotics manufacturers to develop humanoid joint measurement solutions using magnetic sensors.
According to Jung, humanoid robots have between 20 and 50 joints, including those in the neck, shoulders, elbows, fingers and knees. To raise an arm or grasp an object with its fingers, a robot must determine the rotational angle and position of each joint. Encoders measure these movements, providing the information needed to control motors.
Sensor costs increase as the number of joints grows. Fingers present particular challenges because multiple joints are concentrated in confined spaces, making sensor size and weight important considerations. Using different sensors according to accuracy requirements, rather than installing high-precision encoders in every joint, can help reduce costs.
TDK InvenSense's solution uses tunnel magnetoresistance (TMR) sensors and Hall sensors. These measure changes in magnetic fields generated as magnets attached to joints move, allowing the system to determine rotational angles or displacement. Hall sensors can also detect three-dimensional positions in ball-shaped joints.
The two sensor types operate on different principles. TMR sensors use changes in electrical resistance caused by magnetic fields, while Hall sensors measure voltages generated in response to magnetic fields. TMR sensors offer higher measurement accuracy than Hall sensors.
The company is also developing magnetic encoders for joints requiring precise position control. Unlike the simpler angle measurement approach, these devices focus on achieving higher measurement accuracy. TDK InvenSense aims to offer a range of sensors suited to different joint movements and performance requirements.
TDK InvenSense is applying magnetic sensor technology previously used to measure rotational angles, positions and electrical currents in smartphones and automobiles to robotic joints. In robots, magnets with alternating north and south poles can also be used to measure linear displacement, in addition to rotational angles.
"For applications that only require angle measurement, accuracy is likely to be lower than that of encoders, but the sensors are smaller, consume less power and are considerably cheaper," Jung said. "We are working with robotics manufacturers to develop solutions for areas such as fingers, where accuracy requirements are relatively lower."