Abstract: Lidar scanning is used in a variety of scenarios to detect the locations, sizes, shapes, and/or orientations of a variety of objects. The accuracy of such scanning techniques is dependent upon the calibration of the orientation of the lidar sensor, because small discrepancies between a presumed orientation and an actual orientation may result in significant differences in the detected properties of various objects. Such errors are often avoided by calibrating the lidar sensor before use for scanning, and/or registering the lidar data set, but lidar sensors in the field may still become miscalibrated and may generate inaccurate data. Presented herein are techniques for identifying, verifying, and/or correcting for lidar calibration by projecting a lidar pattern on a surface of the environment, and detecting changes in detected geometry from one or more locations. Comparing detected angles with predicted angles according to a predicted calibration enables the detection of calibration differences.

Abstract: A receiving device captures sounds signals (e.g., ultrasonic) from multiple sound signal sources, selects the sound signals satisfying a reliability condition for use in determining an initial position of the receiving device relative to the corresponding sound signal sources, determines the initial position of the receiving device using multilateration of the selected sound signals, and updates the current position of the receiving device as the reliability of individual sound signals varies in the presence of dynamically changing environmental interference, multipathing, and movement between the receiving device and the sound signal sources.

Abstract: A receiving device captures sounds signals (e.g., ultrasonic) from multiple sound signal sources, selects the sound signals satisfying a reliability condition for use in determining an initial position of the receiving device relative to the corresponding sound signal sources, determines the initial position of the receiving device using multilateration of the selected sound signals, and updates the current position of the receiving device as the reliability of individual sound signals varies in the presence of dynamically changing environmental interference, multipathing, and movement between the receiving device and the sound signal sources.