Here are some examples of commonly used sensors: lidar, radar, RGB camera, depth camera, IMU, and GPS. To make things more standard, ROS2 provides the sensor_msgs package that defines the common sensor interfaces. Accordingly, users can use any sensor by any vendor as long as it follows the standard format in sensor_msgs.
As some examples of such messages, let's mention the sensor_msgs/LaserScan, sensor_msgs/PointCloud2, sensor_msgs/Range, and sensor_msgs/Image.
In addition to sensor_msgs package, there are also the radar_msgs and vision_msgs standard interfaces you should be aware of.
For more information, see the API documentation of sensor_msgs, radar_msgs, and vision_msgs.
Let's take a look at some of the common sensor_msgs you might use with Nav2. The complete list of messages can be found in the sensor_msgs documentation.
This message represents a single scan from a planar laser range-finder. This message is used in slam_toolbox and nav2_amcl for localization and mapping, or in nav2_costmap_2d for perception.
This message holds a collection of 3D points, plus optional additional information about each point. This can be from a 3D lidar, a 2D lidar, a depth camera or more.
This is a single range reading from an active ranger that emits energy and reports one range reading that is valid along an arc at the distance measured. A sonar, IR sensor, or 1D range finder are examples of sensors that use this message.
This represents the sensor readings from RGB or depth camera, corresponding to RGB or range values.