Control Algorithm Of Dual-axis Rotation SINS Framework

The inertial navigation system(INS) has been widely used in the submarines and ships due to its independence and passivity. However, the navigation errors of INS accumulate over time, which leads to the failure in satisfying the accuracy requirements of long-time concealed voyage. Compared with the method such as improving the manufacturing technique and accuracy, the rotation modulation has huge advantages in shorter research period, lower cost and easier fulfilment. Through the periodic rotation movement of rotational platform in rotation modulation technique, the inertial sensors’ errors are modulated into periodically-changing signals whose averages are zero. Therefore, these errors can be suppressed effectively. Nevertheless, the rotation movement of rotation platform brings in control errors inevitably, and maneuver of carrier generates angular movements unavoidably, which can enormously influence the effect of rotation modulation. Accordingly, the paper carries out the following research.Firstly, the influence of rotational platform’s control errors to the rotational modulation is analyzed. The error models of inertial sensors and inertial navigation system are established. And the relationship between the effect of rotation modulation and the movement of rotational platform is analyzed. On the basis of the work above, exemplifying classic rotation schemes, the influence of angle overshoot of rotational platform is analyzed. Meanwhile, in the aspects of coordinate transform matrix and null biases’ space accumulation amount, the influence of rotational speed error of rotational platform is analyzed.Secondly, a compound control algorithm is studied. On the basis of active disturbance rejection control(ADRC) technique and sling mode control(SMC) technique, a compound control algorithm is put forward. According to the compound control algorithm, when the control error is big, SMC is mainly used. While the control error declines, ADRC takes over. In this way, both the quick response and steady state accuracy can be guaranteed. What’s more, the chattering caused by SMC can be restrained. Through simulation and experiment results, the effectiveness of the compound control algorithm is proved.Thirdly, a carrier angular motion segregation scheme is put forward. The side effects of horizontal and vertical carrier angular motions to rotation modulation are analyzed. Then based on the rotational speed control, a carrier angular motion segregation scheme is put forward. The effectiveness of the scheme is demonstrated through simulation.