3D sensors in robotic systems work by capturing spatial data about their surroundings, enabling robots to perceive depth and dimensions. These sensors often utilize technologies like LiDAR, stereoscopic cameras, or time-of-flight systems, which measure the time it takes for light to return after reflecting off an object. The captured data is then processed to create a 3D map of the environment, allowing robots to navigate more effectively and perform tasks like object recognition and manipulation. This enhances autonomy and efficiency in robotic operations.