The Research Of Redundant Configuration For Shipborne Strapdown Inertial Navigation System

With the change from the big country to the powerful country in the sea at the present stage,the higher requirements of the navigation accuracy and reliability are needed for the promotion of the warship ability working on the sea.The navigation accuracy and reliability of the system depend on the accuracy and the failure rate of the inertial sensors(gyros and accelerometers).Because of the particularity of warship navigation system,it needed working for a long time continuously.So the warship needs a kind of navigation system which has high accuracy and reliability even the carrier working on very long time.Therefore,it is important practical significance to improve the reliability and accuracy of strapdown inertial navigation system(SINS).The redundancy of device level has the features of simple structure,low cost,light weight.Moreover the reliability of device level is higher than system level with the same number of sensors.In this paper,the redundancy of device level is choosed and take warship SINS as the research object.For the low reliability problems of the traditional orthogonal configuration,the configurations of the redundancy of device level are studied and designed.The accuracy and reliability of redundant configuration are compared when the gyros are four,six and nine respectively.And use the generalized likelihood test(GLT)method to simulate the single-fault and double-fault,verifing its effectiveness.On the basis of configuration,the criteria for redundant configuration are optimized.When the number of gyroscope is 4,the inertial navigation system is changed from a non-redundant state to redundant state.The system reliability increased to 1.75 times than the non-redundant.A symmetrical oblique configuration is presented.The installation angles are optimized by the optimal criteria.And the accuracy and reliability of symmetrical oblique configuration are compared with orthogonal scheme,oblique scheme and cone scheme.Use the GLT method to simulate the single-fault of the symmetrical oblique configuration.The result present that it can be detected.When considering the system cost,weight and other factors,the proposed number of gyroscope is 6.The false alarm rates and missed rares of the dodecahedron configuration are compared with the umbrella configuration.And use GLT method to simulate the single-fault and double-fault of the umbrella configuration.For the advantanges of MEMS,an orthogonal rotation method-based nine-gyro redundant MEMS configuration is presented.The performance of the orthogonal rotation scheme and octadecahedron scheme are comprehensively compared and analyzed.Then use GLT methodto simulate the single-fault and double-fault of the orthogonal rotation configuration and octadecahedron configuration respectively.The simulation results show that the orthogonal rotation configuration can isolate the single-fault and double-fault very well.