Use localization and pose estimation algorithms to orient your vehicle in your environment. Inertial sensor fusion uses filters to improve and combine sensor readings for IMU, GPS, and others. Localization algorithms, like Monte Carlo Localization and scan matching, estimate your pose in a known map using range sensor or lidar readings. Pose graphs track your estimated poses and can be optimized based on edge constraints and loop closures.
To model specific sensors, see Sensor Models.
For simultaneous localization and mapping, see SLAM.