正切细分在捷联寻北方位角解算中的应用

Application of Tangent Subdivision in Azimuth Calculation of SINS

在捷联寻北方位角解算时,采用查表法计算反正切函数存在占用存储空间大和代码执行效率低这两个问题。根据寻北精度对角度计算的要求,提出了一种近似计算角度的方法,该方法首先根据捷联寻北方位角解算时的数据特点将角度分成8个区间,然后在8区间细分的基础上对反正切函数进行分段线性化。给出反正切函数的分段线性方程并通过计算得出该方法的误差不超过3″,完全满足寻北精度的要求,该方法占用存储空间为22 kB,是直接查表法的1/153。采用单片机实现时代码的执行效率明显高于轮询查表法。

There are two problems in the azimuth calculation of SINS by looking-up table to calculate the arc tangent function,the first one is occupying large storage space,the second one is having low code implementation efficiency.A method was put forward to approximatively calculate the angle according to the demand of precision in north finding.Firstly,the angle was divided into eight intervals according to the characteristics of the data in north finding of SINS.Then,the arc tangent function was piecewise linearized.The piecewise linear equations were given,and the calculated error of this method was less than 3″,which could fulfill the demand of precision in north finding.This method only occupies 22 kB storage space,which is just about 1/153 of the calculation method of directly looking-up table.The efficiency of this method is obviously higher than the method of poll looking-up table when used in the SCM.