Melexis has made a significant innovation to improve robots' ability to interact with fragile or diverse objects. The company has revealed Tactaxis, a fully integrated tactile sensor that is compact, soft and delivers the 3D force vector acting on its surface. This enhances robots' hands and grippers, making delicate operations such as fruit picking achievable. The technology has been successfully implemented in a functioning prototype.
The ground-breaking prototype provides multiple 3D magnetometer pixels, using its Triaxis technology. The sensor is accompanied by a magnet embedded into an elastomer material. This offers a soft contact interface, simulating the attributes of human skin. The arrangement provides a high sensitivity to detect even small amounts of force to induce a response. The achieved force resolution is 2.7mN which is enough to distinguish weight change of a fraction of a gram (~0.3g). The prototype is extremely compact (with dimensions of only 5mm x 5mm x 5mm) and ideal for tight spaces.
The gradiometric approach makes the sensor immune to magnetic stray fields, stopping possible measurement errors. It is also tough enough to cope with harsh conditions (temperature variations, etc.). Unlike competing optically-based tactile sensors, it is fully integrated. It will be possible to create high volumes of factory-calibrated sensors, and this semiconductor process results in significant cost and reliability benefits.
"Robots need the sense of touch to manipulate fragile objects. For such applications, we have developed a novel magnetic sensor to accurately measure the contact force – while being robust against disturbances," explains Gael Close, global innovation manager at Melexis. "By exploiting the capabilities of our Triaxis magnetic sensor technology, we have made a significant step forward in robot tactile sensors, providing a rugged and competitive multi-axis sensing solution. We will now use the Tactaxis prototype as the foundation for further development work."
A white paper giving details on the Melexis 3D magnetic force sensor prototype has been published by IEEE (Institute of Electrical and Electronics Engineers): T. Le Signor, N. Dupré, and G. Close, "A gradiometric magnetic force sensor immune to stray magnetic fields for robotic hands and grippers", IEEE Robotics and Automation Letters, Jan. 2022.