High precise attitude updating algorithm for SINS using angular rate

In strap-down inertial navigation system (SINS), the attitude updating algorithms using angular rate have superior performance than conventional ones using angular increment for modern-day gyro whose output is angular rate. However, most of them are obtained by omitting the higher order cross product in the rotation vector differential equation, which leads to degrade the accuracy of algorithms inevitably and cannot restrain noncommutativity error in the high dynamic condition. Due to the limitation on the computer performance and modern-day gyro technology, it is impossible to increase sample numbers and update frequency infinitely for the purpose of improving the attitude accuracy. To solve this problem, the new algorithm deducted by adding the higher order cross item is proposed. Simulations are carried on under coning motion. While angular rate is used as algorithm input, the accuracy and stability of attitude computation can be improved effectively as compared with conventional ones and others using angular rate.