基于光纤陀螺的二位置寻北系统采用捷联式方法寻北,具有寻北快速和结构紧凑等特点.选择标度因数接近的2只光纤陀螺,敏感轴垂直布置于转位机构上,在步进电机的驱动下,实现二位置变换.步进电机经减速后的驱动轴与惯性测量单元支架的旋转轴组成内外嵌套的共轴传动系统,可使结构紧凑、刚度较大,有利于保证转位机构的精密快速旋转.硬件电路采用DSP为核心处理器,负责光纤陀螺和加速度计数据采集与寻北解算等.构建样机进行转位、单位置重复性与圆周精度测试,测试结果表明:转位精度为30″,单位置重复性与圆周精度小于0.1.,转动过程加数据采集过程的整个寻北时间小于3min,满足预期的设计指标.%Two-position north-finding system based on fiber-optic gyroscope can be designed with strapdown style, which has the merits of quick finding and compact structure. Two fiber-optic gyroscopes with approximate scale factors are used and placed on the indexing mechanism with sensing axis maintaining vertical. The mechanism is driven by stepper motor to realize two-position changing. The reducer output shaft and revolving shaft of inertia measurement element holder composed inward-outward coaxial driving form,which is propitious to quick and accurate rotation for compact and high stiffness properties. DSP is used as the core processor of hardware for data acquisition of fiber-optic gyroscopes and accelerometers, and for north-finding resolve. Prototype instrument is built and tests of indexing,single-station repeatability and peripheral precision are done. The test results show that indexing precision is 30",single-station repeatability and peripheral precision is less than 0. L°,the time of north-finding is less than 3 min and meet the anticipated design target.
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