Precise Time Delay Measurement and Compensation for Tightly Coupled Underwater SINS/piUSBL Navigation

2025-10-27

AI Summary

In underwater inertial/acoustic integrated navigation, sensor timing asynchrony degrades observability and navigation accuracy. To address this, this paper proposes a tightly coupled SINS/piUSBL/depth sensor navigation framework. We innovatively design a time-delay measurement strategy integrating precision time synchronization and acoustic signal processing, explicitly modeling the traditionally unobservable propagation and processing delays as estimable parameters. By combining time-of-arrival analysis with a precise time-synchronization protocol, strict temporal alignment is achieved across heterogeneous measurements—namely bearing, slant range, and depth. Simulation and experimental results demonstrate that the proposed method significantly enhances system robustness to timing delays: the root-mean-square error (RMSE) of navigation is reduced by 40.45%, and the maximum error decreases by 32.55%. These improvements validate the effectiveness of the framework in enhancing both accuracy and reliability of underwater navigation.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation
• Search and Optimization: Distributed Search

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications
• Security and Privacy: Large-scale security measurements
• Semantics and Knowledge: Methods to enhance, augment, integrate or synergize semantic models such as knowledge graphs and LLMs

Abstract

In multi-sensor systems, time synchronization between sensors is a significant challenge, and this issue is particularly pronounced in underwater integrated navigation systems incorporating acoustic positioning. Such systems are highly susceptible to time delay, which can significantly degrade accuracy when measurement and fusion moments are misaligned. To address this challenge, this paper introduces a tightly coupled navigation framework that integrates a passive inverted ultra-short baseline (piUSBL) acoustic positioning system, a strapdown inertial navigation system (SINS), and a depth gauge under precise time synchronization. The framework fuses azimuth and slant range from the piUSBL with depth data, thereby avoiding poor vertical-angle observability in planar arrays. A novel delay measurement strategy is introduced, combining synchronized timing with acoustic signal processing, which redefines delay-traditionally an unobservable error-into a quantifiable parameter, enabling explicit estimation of both acoustic propagation and system processing delays. Simulations and field experiments confirm the feasibility of the proposed method, with delay-compensated navigation reducing RMSE by 40.45% and maximum error by 32.55%. These findings show that precise delay measurement and compensation not only enhance underwater navigation accuracy but also establish a generalizable framework for acoustic positioning integration, offering valuable insights into time alignment and data fusion in latency-sensitive multi-sensor systems.

Problem

• Addresses time synchronization challenges in underwater multi-sensor navigation systems
• Quantifies and compensates for acoustic propagation and system processing delays
• Enhances navigation accuracy by integrating SINS, piUSBL, and depth data

Innovation

• Tightly coupled SINS/piUSBL/depth gauge fusion framework
• Delay measurement via synchronized timing and acoustic processing
• Quantifying acoustic propagation and system processing delays