Development of Flexible Highly Precise Ultrasonic Sensors for Safety Control in Human–Robot Collaboration

Proximity sensing is of great importance for robot control during human–robot collaboration (HRC). Commonly used machine vision sensors or photodetectors are subjected to the light block especially during close HRC, while capacitive sensors are easily interfered by the electromagnetic signal from the robot itself and its environment. Here, we present a flexible ultrasonic sensor system for proximity sensing, aiming to enhance safety controls during HRC. The sensor achieves an accuracy of 3 mm over a detection range of 510 mm. A minimum of 12 sensors are integrated into a flexible printed circuit board (FPCB), which functions as a wearable sensing system for a commercial robot. The sensor system effectively detects the position of objects around the robot in real time and covers all detection ranges in the detection plane at all angles, which is employed to control the robot in HRC. The manuscript delineates the sensors’ performance, outlines the design of an ultrasonic sensor array for proximity sensing, and introduces a reliable method for secure and cooperative HRC control.