垂线偏差对CHZ-Ⅱ重力仪稳定平台姿态精度的影响

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

为研究重力垂线偏差对CHZ-Ⅱ重力仪稳定平台水平姿态精度的影响,建立了包含重力扰动的平台惯导系统的组合导航模型,通过能观性分析,给出了平台水平姿态角的极限精度,分析了出测前基点比对、测线作业、收测后基点比对3个阶段中垂线偏差对平台水平姿态精度的影响,并对是否进行垂线偏差补偿给出了指导性建议。出测前基点比对时,平台水平姿态角精度受当地垂线偏差和加速度计零偏水平分量的综合影响,要根据垂线偏差的方向决定是否进行垂线偏差补偿;测量作业中和收测后基点比对时,平台水平姿态角精度只受平台所在地垂线偏差影响,补偿垂线偏差能够提高稳定平台的水平姿态精度。仿真结果与理论分析一致。

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-Ⅱgravimeter,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.