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Abstract
The integration of Global Navigation Satellite System (GNSS) and Inertial Navigation System (INS) technologies is a very useful navigation option for high accuracy positioning in many applications. However its performance is still limited by the GNSS satellite availability and the geometric configuration. To address this limitation, an alternative, non-GNSS-based positioning technology can augment the traditional integrated GNSS/INS system. Locata is a terrestrial-based technology which transmits GNSS-like ranging signals. This research is focused on the integration of GNSS, Locata and INS technologies so as to provide accurate and reliable navigation coverage. The main research contributions are:
1. An "on-the-fly" (OTF) Locata resolution algorithm that takes advantage of geometry change is proposed which allows the carrier phase ambiguities resolved without the initialisation on a precisely surveyed point. The experiment confirms the effectiveness of the Locata OTF algorithm. A Locata/INS integration system has also been developed and tested.
2. A new Precise Point Positioning (PPP) technique, augmented by Locata measurements is proposed, where Locata and GNSS carrier phase measurements are processed simultaneously in a "tightly-combined" mode. The field experiment indicates the advantage of the proposed method in terms of accuracy and convergence times.
3. A multi-sensor navigation system is designed based on the integration of PPP-GNSS, Locata and INS. To achieve better system performance three data fusion algorithms - Centralised Kalman Filtering (CKF), Federated Kalman Filtering (FKF) and Global Optimal Filtering (GOF) - are analysed. The comparative studies confirm that the FKF and CKF solutions have the same accuracy and the GOF solution has a higher accuracy.
4. The proposed PPP-GNSS/Locata/INS multi-sensor navigation system has been improved with an adaptive fault-tolerant GOF algorithm. To evaluate the system performance, GNSS failures were simulated and incorporated into real experiment data files. The result verifies the reliability and fault-tolerant capability of the proposed system.
5. A new indoor navigation methodology - the position and attitude modelling system (PAMS) - has been proposed with the use of the "V-Ray" antenna. The PAMS can output the complete set of navigation parameters position, velocity, acceleration and attitude. An indoor test conducted in a metal warehouse confirms the accurate solutions in indoor environments.