Strapdown Vehicle Gravimetry Nonmodel Error Compensation Method.

In strapdown vehicle gravimetry, a new phenomenon was discovered by strapdown vehicle gravimetry error model analysis and simulation. That is, after compensating all error terms in the gravity measurement error model, there is still residual error in gravity results, which could not be described by the model. In response to this, multiscenario simulations were carried out to study the characteristics of this residual nonmodel error. Simulations manifest that the nonmodel error has close relationship with the navigation data recorded during strapdown vehicle gravity measurement. On the basis of this, this letter proposed a strapdown vehicle gravimetry nonmodel error compensation method. This method could estimate the nonmodel error by strapdown vehicle gravimetry simulation, employing the real integrated navigation data and the strapdown inertial navigation system (SINS) real trajectory generator. The effectiveness of the proposed method was verified by a real strapdown vehicle gravimetry test in Changsha. Test results show that the repeatability of the repeat lines under 200 s filtering has been improved from 0.51 to 0.41 mGal, 19.6% increase in accuracy. It demonstrates that the proposed method is correctness and validity in real strapdown vehicle gravimetry application.