Mutant fault diagnosis method of underwater integrated navigation system

The invention discloses a mutant fault diagnosis method of an underwater integrated navigation system. A traditional residual error detection method is improved aiming at the characteristics of an integrated navigation structure according to the characteristics of a fault type; after the improved residual error detection method is used for diagnosing the mutation type fault of the auxiliary navigation equipment, the noise mutation and the information mutation type system fault are distinguished through a residual error mean value and a residual error absolute sum value; if the information mutation fault occurs in the system, the system is isolated until the fault is eliminated; and if the noise mutation fault occurs in the system, an adaptive filtering algorithm is started, and the systemis recovered. According to the method, the fault of a noise sudden increase type system and the fault of an information mutation type system can be distinguished, misjudgment cannot occur when the mutation type fault is diagn