Design and Simulation of OAS/INS/GPS/APS Integrated Navigation System

It is presented the development of an integrated navigation system for an under water vessels using three new navigation sub-systems to integrate with inertial navigation system (INS). The three sub-systems are GPS altitude determination system, acoustic positioning system (APS) and optical alignment system (OAS), each offering high accuracy in different conditions with different working principles and features. Integration of GPS, INS, APS and OAS would fuse together the virtues of each system for a better performance. Thus the federated Kalman filter (FKF) algorithm is employed in this integrated system, which is based on two reasons. The first one is that there are more than two navigation sub-systems involved, using FKF could overcome the disadvantages of the traditional centralized Kalman filter (CKF), which is suffer from dimension disaster, lower real-time capability and worse robustness. The second one is that the integrated system has different integrated modes in different working conditions. For example, it employs INS/GPS integrated mode mostly when the vessel navigates surface, and uses INS/APS or only INS mode when it sails underwater. When the vessel is surface near the shore, the integrated system takes OAS/INS/GPS integrated mode. Hence, different integrated methods are decided by different kinds of sub-systems signal acquired. Using FKF can simply detect the valid system and select an optimal mode to accomplish optimal parameter calculation, and to decrease the complexity of system mode and algorithm. Numerical results prove that the integrated navigation system is capable of providing higher accuracy both in location and in azimuth.