A Capacitive and Piezoresistive Hybrid Sensor for Long-Distance Proximity and Wide-Range Force Detection in Human-Robot Collaboration

Safety is a core concern in human-robot collaboration (HRC), which highly relies on multi-information collected from its environment by various sensors. Current passive solution is to isolate the robot from human by fences or cages, which is invalid for a real collaborative robot, especially for the domestic and rehabilitation robots. Herein, a capacitive and piezoresistive hybrid sensor for long-distance proximity and wide-range force detection in HRC is reported. The sensor composes a pair of interdigital copper foil worked as the electrode for both coplanar capacitors and resistors, while a carbon black in polymer matrix works as the piezoresistive material. As-prepared hybrid sensor can detect the object approaching as far as 100 mm, while a contact force covers from 0 to 450 N. The maximum sensitivity is 0.65 mm(-1) for object proximity, and 17.73 N-1 for contact force. Significantly, the proposed hybrid sensor is feasible and scalable integration for the electronic-skins (e-skins) with superior stability, mechanical flexibility and deformability, which can withstand large compression, bending and torsion in applications. Finally, the e-skins are used for safety control in two types of commercial robots, which exhibits the long-distance proximity and large-range force detection capabilities, illustrating its potential usage in complex, precise, and safe requirement conditions.