Electromagnetic Field & ToF Sensor Fusion for Advanced Perceptual Capability of Robots

Effective and safe physical Human-Robot Interaction (pHRI) hinges on robot proximity and tactile perception. This paper introduces a triple-mode fusion sensor designed to enhance safe pHRI. The sensor combines electromagnetic field radiation sensors and an infrared Time-of-Flight (ToF) sensor on a single hardware platform. This fusion equips the sensor with three types of perceptual capabilities, enabling robots to excel in proximity and tactile sensing. Electric field sensing excels in close-range proximity detection with a wide field of view (FoV), while the infrared ToF sensor is proficient in long-range proximity detection despite its narrow FoV. Magnetic field sensing with a switching shield mechanism identifies when the sensor is pressed. Furthermore, a proposed self-curve fitting algorithm enables the capacitive sensor to overcome its limitation resulting from nonlinearity and the dependency on the physical properties of detected objects. In summary, this sensor facilitates seamless interaction between humans and robots by providing integrated perception information. Experimental results have shown that the sensor achieved a capacitive measurement range of up to 28 cm and can measure tactile forces of up to 40 N, implementing both capacitive proximity sensing & inductive tactile sensing and the self-curve fitting.