An improved fault tolerance method of GPS/INS integrated navigation system

In the field of integrated navigation, integrated GPS/INS system has always been a research hotspot, as the advantages of GPS (Global Positioning System) and INS (Inertial Navigation System) are complementary. Typical fault-tolerant designs of integrated GPS/INS system assume an accurate INS reference system whose performances are security, reliable and fault-free. Once a fault is detected, it is thought that GPS fails. There is one question that sometimes the presumption is unreasonable: the performances of a low-quality inertial measurement unit (IMU) are not reliable; high-quality inertial sensors can also fail sometimes. Although the probability is small, it will be a catastrophe once the failure occurs without being detected. In addition, high-quality inertial sensors are too expensive. Typical means to ensure the reliability of INS are hardware system or component redundancy technology, which makes a higher coat. When the assumption does not hold, we cannot locate a fault and realize fault isolation and accommodation. This paper presents a method to locate faults in the integrated GPS/INS system to improve its reliability when the assumption does not hold. We introduce IMM (Interacting Multiple Model) in the integrated GPS/INS system. IMM is integrated with GPS to provide analytical redundancy information. We can realize faults location, fault isolation and accommodation through the analytical redundancy information provided by IMM. When INS fails, IMM replaces INS temporarily to realize filtering and positioning so that the integrated system can run with no interruption. This method can improve the system reliability with cost saving. Simulation results are presented to verify the proposed method.