Abstract: The 3-interval expression of 4-sample rotation vector, optimal 4-sample rotation vector, and Savage’s algorithms are constructed. The differences of 3-interval approach and traditional 2-speed approach are studied. The performance of the algorithms constructed in this paper and the algorithms proposed by Ignagni under the variation of samples is testified. The results show that, 3-interval approach can not improve the precise of attitude updating impressively, but it can boost the efficiency of the algorithms.

Key words: strapdown inertial navigation, attitude updating, rotation vector, 3-interval, precise analysis, efficiency analysis

摘要： 构造了四子样旋转矢量算法、优化四子样旋转矢量算法、Savage方法的三时间间隔表示。分析了三时间间隔结构和双速结构的区别。验证了构造的算法和Ignagni等人提出的系列算法在样本数变化时的性能。结果表明，三时间间隔结构不能显著地提高姿态更新算法的精度，但是可以提高算法的效率。

关键词: 捷联惯导, 姿态更新, 旋转矢量, 三时间间隔, 精度分析, 效率分析