A Self-Capacitance Proximity E-Skin With Long-Range Sensibility for Robotic Arm Environment Perception

Proximity sensing is a major requirement for intelligent robots and robotic arms to ensure safety and closed-loop control in human–robot interactions. E-skins have received increasing attention because of their ease of arraying and installation. However, problems, such as insufficient sensing distance and inaccurate distance prediction, still exist. To solve these problems, we propose a self-capacitance-based long-range proximity-sensing e-skin. First, two electrode shape classifications, external edge and internal holes, were analyzed and optimized in COMSOL to explore the variation trends of charge distribution and capacitance proximity characteristics. Then, based on the self-capacitance proximity theory, the parameters of the fitting function for the actual capacitance–distance curves for the four electrodes were solved using the planning solution method. The results show that the sensor has a good dynamic response, a long proximity-sensing range (10.9 cm), high distance estimation accuracy ( $\sigma ={0}.{45}{)}$ , and good repeatability ( $>$ 2 h). Finally, we integrate the sensor array with the end joint of the robotic arm to complete a sorting task. A closed-loop control demonstration of safe obstacle avoidance and deceleration was achieved, thereby demonstrating the great potential of e-skin for future human–machine collaboration scenarios. Index Capacitive sensor, proximity sensor, robot skin, sensing-distance.