Safe physical human-robot interaction: A quasi whole-body sensing method based on novel laser-ranging sensor ring pairs

Non-contact detection is a competitive method for ensuring safety in close human-robot interaction (HRI). However, existing sensor configuration methods have difficulty satisfying the requirements for covering a wide range of sensing zones with fewer spots and a low-cost, low-complexity processing system. In this study, we developed a novel laser-ranging sensor configuration comprising sensors mounted on ring pairs, thereby implementing quasi whole-body sensing and cooperative location with fewer sensors. Each sensor ring pair was composed of double sensor rings mounted at opposite ends of robot arms. Based on the cone detection zone of each laser-ranging sensor, an optimisation of the configuration parameters showed that the maximum sensing volume coverage could be obtained when the laser-ranging sensors on each sensor ring were mounted in a tilted and biased form at certain angles. According to detection data and robot arm kinematics, a cooperative location model was also established to estimate the intervention position. Furthermore, we presented a self-occlusion geometric detection method for the robot, so as to identify cases in which the robot body entered the detection zone of the sensor ring pairs. To validate the efficacy of the proposed methods, experiments on quasi whole-body sensing, cooperative location, and self-occlusion detection were conducted with a UR10 robot. The experimental results show that the proposed sensor ring pair and detection method can effectively detect an approaching human and effectively estimate the intervention position and self-occlusion, allowing for efficient and safe cooperative performance with humans.