An intelligent inspection and positioning system based on dual-antenna GNSS/INS

The road inspection vehicle requires accurate, real-time location data during inspection tasks. This paper presents an advanced navigation system for such vehicles, utilizing dual-antenna Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS) tightly coupled technology. The system delivers continuous, precise location data by leveraging pseudo-range double-difference observations, which enhance the observation matrix structure, reduce reliance on original data, and address integer ambiguity issues. These improvements also increase the fault tolerance of the system. The extended Kalman filter (EKF) is employed to fuse raw GNSS data with INS estimates, enabling real-time error correction and enhancing navigation accuracy and reliability in both static and dynamic conditions. An experimental platform was established to evaluate the system in simulated highway inspection scenarios. Results demonstrate that the system achieves horizontal positioning errors within 0.0225 m under static conditions, with centimeter-level accuracy and a directional baseline error of 0.14°/2 m. The GNSS/INS system shows smaller error fluctuations compared to the standalone GNSS system, with average errors of 0.0085, 0.0094, and 0.0156 m in the East, North, and Up directions, respectively, compared to 0.0363, 0.0391, and 0.0573 m in the standalone GNSS system. In dynamic tests, the GNSS/INS system outperforms the standalone GNSS system in positioning accuracy, stability, and precision. It demonstrates high stability across varying azimuths, while the standalone GNSS system experiences larger error fluctuations at certain azimuths. The integration of EKF significantly enhances performance in environments with signal obstructions and noise, showcasing robust anti-interference capabilities. In conclusion, the GNSS/INS system with EKF fusion offers significant improvements in positioning accuracy, stability, and reliability, particularly in complex environments. Compared to existing standalone GNSS systems, it provides enhanced inspection capabilities, making it a promising solution for real-world highway inspection tasks.