Comparison of Performance Between Loosely and Tightly Coupled GNSS/INS in Real Scenarios

The Global Navigation Satellite System (GNSS) is commonly combined with the Inertial Navigation System (INS) to provide reliable navigation services even in environments where GNSS signals may be limited. The GNSS/INS coupled navigation system can be implemented in three modes: loosely coupled, tightly coupled, and deeply coupled. While the deeply coupled system offers superior performance, it requires adjustments to the receiver's signal tracking loop, making it less practical for widespread use. Therefore, this paper focuses on the loosely coupled and tightly coupled algorithms due to their broader applicability. Outdoor experiments were conducted in both dense forest and open square areas, utilizing GNSS signals of varying quality. The results indicate that the tightly coupled system generally outperforms the loosely coupled system, particularly in degraded GNSS signal environments, with improved positioning accuracy.