RotOptiLink: A Novel Mechanism for Minimizing Limited Vision Spots With an Integrated Rotational Optical Sensing Device in Manipulator Links

As robotics technology advances and the fifth industrial revolution unfolds, bringing robots closer to human life, research on ensuring human safety in shared workspaces has become crucial. Among these studies, manipulators, which are widely used in various fields, have gained prominence. Existing research predominantly employs sensor ring and sensor skin types for safety assurance by measuring robot-human distances. Sensor rings, with fewer sensors and lower costs, suffer from blind spots. Conversely, sensor skin types, despite being blind spot-free, incur high computational and fabrication expenses. Our proposed solution, RotOptiLink, integrates a rotational optical sensing device into manipulator links, combining the benefits of both types while mitigating their drawbacks. RotOptiLink utilizes a slip ring mechanism, enabling the outer ring, equipped with distance sensors, to rotate while maintaining contact with the inner ring, which carries power and signal processing lines. This setup allows for the detection of approaching individuals and obstacles without blind spots, even with a small number of sensors. We mathematically generalize design parameters, validate them experimentally, and demonstrate omnidirectional obstacle sensing on a three-axis manipulator.