System-level identification algorithm for quadratic model parameters of gyro bias

Based on the single-axis SINS, the strict mathematical relationship between the system position err and the azimuth gyro drift error was derived under the level damp mode by assuming that the level-gyro constant drift could be fully modulated and the azimuth gyro drift was changed with time and could be expressed as a quadratic model. The error models of azimuth gyro drift were set when with constant terms, one-time items, the quadratic terms and the all-coefficient model, respectively. Various parameters in the quadratic model were effectively identified by using a recursive least squares algorithm. Simulation results show that the constant coefficient can be identified firstly, the estimated time is in about 14 h, the estimated error is 6.54e-6 (°)/h; then the one-time items coefficient is identified, and the estimated time is about 30 h, the estimated error is 2.73e-8 (°)/h; finally the quadratic coefficient is identified, and the estimated time is about 42 h, the estimated error is 1.51e-9 (°)/h. The estimated time of the all-coefficient model is about 45 h, and the estimated error is 7.28e-6 (°)/h. The identification results demonstrate the correctness of the algorithm. In order to achieve better recognition results in the practical engineering system, we can increase the total identification time appropriately.