On-line Calibration Method For Ship Strapdown Inertial Navigation System

This paper is mainly about the online calibration method research of marine instrapdown inertial systems. As time go on, the electronic compenonets of strapdown inertialsystem will be ageing, wearing and so on to a certain extent. Meanwhile, when the strapdowninertial navigation system is at work, the inertial sensors will suffer the vibration, shock,temperature fluctuations and other environmental effects of the hull directly, and whatmentioned above will result in some reducation of the accuracy of navigation after working ina period of time, so it is necessery to calibrate the inertial system devices.The traditional calibration method is to remove the inertial compenonets from thetransport carrier at intervals of some time, and begin the laboratory calibration again afterre-installing all the compenonets on the turntable, with a larger span between the calibrationlocation and using location, great inconvenience in the actual use and maintenance could bemade, as well as the enormous waste of human and material resources. In order to improvethis situation and extend the calibration cycle,the online calibration method is proposed,whichmakes use of the GPS external informations and related error terms of the ships’ ownmaneuvering related to strapdown inertial navigation system to do the calibration.Thiscalibration method doesn’t need the support of the huge turntable,so it avoids the dependenceon the turntable of traditional method. The main content of this paper are as following:First, given principle of the online calibration research methods of strapdown inertialsystems, according to the basic principles of inertial navigation system, gives the equation andthe strapdown matrix differential equations of the system, analyzes the system’s main errorsource of inertial navigation system, derives the layout of program formula of inertialnavigation system, which includes the derivation and calculation of the attitude matrix,longitude and latitude, the speed and so on, at the same time, gives the error mode of onlinecalibration of the strapdown inertial system, and the effect of the accelerometer bias and gyrobias could be made on the system. We can make a conclusion from the result of simulationthat the related error terms of accelerometer and gyroscope have a significant impact on theaccuracy of navigation of the system, and the error will increase with the accumulation oftime.Secondly, introduces the observability of the online calibration of strapdown inertialnavigation system,and then introduces the analysis theories and methods of the observabilityof PWCS in detail, analyzes incentives of the systematic errors, according to the different error incentives to design five calibration paths of online calibration of the strapdown inertialsystem, and do the considerable measure analysis of such five different calibration paths.Making the analysis of error parameters of the system in the different state of motion as wellas the observability with the analysis theories of the observability of PWCS designing thetrajectory generator and doing the simulation analysis of the error parameters of the differentpaths with the Kalman filter.The results show that the online calibration with some referencevalue is feasible theoretically.