Range Sensor 22 . Range Sensors

Range sensors are devices that capture the threedimensional (3-D) structure of the world from the viewpoint of the sensor, usually measuring the depth to the nearest surfaces. These measurements could be at a single point, across a scanning plane, or a full image with depth measurements at every point. The benefits of this range data is that a robot can be reasonably certain where the real world is, relative to the sensor, thus allowing the robot to more reliably find navigable routes, avoid obstacles, grasp objects, act on industrial parts, etc. This chapter introduces the main representations for range data (point sets, triangulated surfaces, voxels), the main methods for extracting usable features from the range data (planes, lines, triangulated surfaces), the main sensors for acquiring it (Sect. 22.1 – stereo and laser triangulation and ranging systems), how multiple observations of the scene, e.g., as if from a moving robot, can be registered (Sect. 22.2), and several indoor and outdoor robot applications where range data greatly simplifies the task (Sect. 22.3). 22.1 Range Sensing Basics ............................ 521 22.1.1 Range Images and Point Sets ......... 521 22.1.2 Stereo Vision ............................... 523 22.1.3 Laser-Based Range Sensors ........... 527 22.1.4 Time-of-Flight Range Sensors........ 528 22.1.5 Modulation Range Sensors ............ 529 22.1.6 Triangulation Range Sensors .......... 529 22.1.7 Example Sensors .......................... 530