Precise Relative Positioning for Tandem Drifting Cars

Adyasha Mohanty, Remy Zawislak, Sriramya Bhamidipati, and Grace Gao

Abstract:	Drifting provides insights into how autonomous cars handle excursions past stable limits. So far, autonomous drifting has been demonstrated for a single car where GPS carrier phase measurements provide cm-level accuracy in absolute position via base station corrections. We aim to extend the single car drifting to tandem drifting. However, in autonomous tandem drifting, it is hard to guarantee cm-level accuracy in relative position using standalone carrier phase measurements since noisier drift dynamics create a large search space of integer ambiguities which makes integer fixing challenging. We propose a precise relative positioning framework for tandem drifting where we use drift dynamics to aid carrier phase measurements. Utilizing drift dynamics, we create an a priori estimate of relative position that constrains the physical search space, and the induced integer search space. To improve integer ambiguity fixing rate, we adaptively adjust the integer search space based on the noise in drift dynamics. We demonstrate our algorithm’s performance on a simulated tandem drifting case. Our algorithm achieves cm-level accuracy even with noisy GPS measurements and shows improved positioning over conventional methods such as LAMBDA.
Published in:	Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021) September 20 - 24, 2021 Union Station Hotel St. Louis, Missouri
Pages:	113 - 124
Cite this article:	Mohanty, Adyasha, Zawislak, Remy, Bhamidipati, Sriramya, Gao, Grace, "Precise Relative Positioning for Tandem Drifting Cars," Proceedings of the 34th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2021), St. Louis, Missouri, September 2021, pp. 113-124. https://doi.org/10.33012/2021.17871
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