Flexible dual-mode sensor with accurate contact pressure sensing and contactless distance detection functions for robotic perception

This paper presents a novel flexible dual-mode sensor with both contact pressure and distance sensing abilities for robotic grasping and manipulation applications. The proposed flexible dual-mode sensor measures contactless distances by flat interdigitated electrodes, based on electrical field detection principle. Meanwhile the sensor detects contact pressures by truncated pyramid-shaped porous composites based on graphene nanoplate and silicone rubber. Both the functions of the sensor are encapsulated by cascading assembly, the different sensing units are nested and arranged to avoid coupling effects between different sensing signals. The structural design, working principle, and fabrication process to make the flexible dual-mode sensor were presented. Characterization tests showed that the developed flexible dual-mode sensor has a high sensitivity of 0.33 V/N and stability for contact pressure sensing, this sensor can also detect the distances between objects and sensor with high accuracy. The dual-mode sensor was then mounted onto a robotic arm to perform object's grasping and collision experiments, results demonstrated that the sensor can accurately measure the distributed contact force and distance between objects for tactile perception. Thus, our proposed flexible dual-mode sensor would have great prospects in robotic safety detection and manipulation applications.