Robotics
Odometry
Definition
Odometry estimates changes in a robot's position and orientation from motion measurements over time. Its accumulated pose provides a local reference that can drift as measurement errors build up.
Updated
A local account of movement
Odometry follows how far and in which direction a robot has moved relative to a starting reference. Wheels can supply encoder-based motion measurements, while cameras and inertial sensors provide other sources. ROS REP 105 explicitly lists wheel odometry, visual odometry, and inertial measurements as inputs to the local odometry frame.
For a humanoid, an odometry estimate can tell the navigation system how its body has moved during a walking sequence. The word does not imply that the robot has wheels.
Continuity and drift serve different needs
ROS defines the odom frame so the reported pose changes continuously. This makes it useful for short-term motion control. Accumulated errors, however, mean the same frame is unsuitable as a guaranteed long-term global reference.
The map frame can incorporate global corrections and may jump when a localization estimate changes. Confusing these frames can cause abrupt changes in a controller that expected smooth feedback.
Odometry is not a complete map
SLAM adds map estimation and constraints from revisiting places. Odometry alone does not establish the layout of a building or identify a safe route through it.
Sources
Related terms
Visual-inertial odometry
Visual-inertial odometry estimates a moving system's motion by combining camera observations with inertial measurements. It typically estimates position, orientation, velocity, and sensor biases over time.
Simultaneous localization and mapping
Simultaneous localization and mapping is the joint estimation of a robot's state and a map of its environment from sensor observations. It is commonly abbreviated SLAM.
Pose estimation
Pose estimation determines the position and orientation of an object or robot relative to a reference frame. For a rigid body in three-dimensional space, a full pose has three translational and three rotational degrees of freedom.