Transfer Alignment Using Synergistic IMUs

Shahram Moafipoor, Brad Despres, Jeff A. Fayman, Lydia Bock

Peer Reviewed

Abstract:	With the proliferation of unmanned autonomous vehicles, many new applications have arisen in which a host vehicle carries one or more smaller participant unmanned vehicles. These participants are deployed from the host vehicle and return to the host vehicle after their mission is complete. Examples exist in airborne, seaborne, as well as land-based applications. To enable such applications, the navigation solution of the host platform must be transferred to the participant as it is deployed to initialize the participant’s own navigation system state. Transfer alignment is the process of determining the initial position, attitude, and calibration of an inertial navigation unit attached to a host platform’s navigation system and transferring it to the participant upon release. This technique is widely used for torpedoes, weapons and missiles dropped from a carrier’s navigation system. This also applies to human occupants with wearable IMUs exiting a manned transportation vehicle. The method typically relies on fixed alignment of the host and the released device. This paper presents two novel computational inertial sensing techniques with applications in participant transfer alignment that don’t rely on fixed alignment between the host and release device. In the first, a Total Least Square technique with the Error-in-Variable (EIV) is implemented to estimate the attitude misalignment between two IMUs. In the second, the relative positions of participant IMUs with respect to the host vehicle are estimated with a learning optimal state estimator technique whereby the host platform is in motion and inertial sensors are exposed to different inertial measurements en route. These transfer alignment methods are then demonstrated with real-world data. The data analysis shows these approaches can estimate the attitude and position alignment between multiple IMUs with accuracy up to 0.1° and 0.1m, respectively.
Published in:	Proceedings of the ION 2019 Pacific PNT Meeting April 8 - 11, 2019 Hilton Waikiki Beach Honolulu, Hawaii
Pages:	594 - 605
Cite this article:	Moafipoor, Shahram, Despres, Brad, Fayman, Jeff A., Bock, Lydia, "Transfer Alignment Using Synergistic IMUs," Proceedings of the ION 2019 Pacific PNT Meeting, Honolulu, Hawaii, April 2019, pp. 594-605. https://doi.org/10.33012/2019.16775
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