Influence Analysis of Vertical Deflection on Attitude Accuracy of CHZ-Ⅱ Gravimeter Stabilized Platform

  Objectives  CHZ-Ⅱgravimeter is the second generation platform gravimeter developed by China independently, for marine and airborne gravimetry. The attitude accuracy of gravimeter stabilized platform affects the measurement accuracy of gravity anomaly directly. The gravity vertical deflection is one error source affecting the horizontal attitude accuracy of the stabilized platform, so it is necessary to study the influence of gravity vertical deflection on the horizontal attitude accuracy of CHZ-Ⅱgravimeter stabilized platform.

  Methods  According to the working principle of the inertial stabilized platform of CHZ-Ⅱ gravimeter, the integrated navigation model containing gravity disturbance of the platform inertial navigation system is established. The observability of the model in static state is analyzed, and the ultimate accuracy of platform horizontal attitude angle is given. Then, the influence of the vertical deflection on the horizontal attitude of the platform in three stages as base point comparison before surveying, operation on survey lines and base point comparison after surveying, is analyzed. The influence of attitude accuracy is discussed, and some valuable suggestions are given on whether to compensate the vertical deviation.

  Results  The horizontal attitude angle accuracy of the platform is affected by the local vertical deviation and the horizontal component of accelerometer bias when comparing base point before survey. And it is decided whether to compensate the vertical deviation according to the direction of gravity disturbance. When comparing base point after survey, or operating on survey lines, the horizontal attitude angle accuracy of the platform is only affected by the vertical deviation of the platform location, and compensating the vertical deflection can improve the horizontal attitude accuracy of the platform.

  Conclusions  When the accelerometer bias cannot be observed, whether to compensate the vertical deflection should be determined according to the direction of the vertical deflection. When the accelerometer can be observed, the horizontal attitude accuracy of the stabilized platform can be improved by the compensation of vertical deflection.