Abstract: Aiming at the problem that the third-generation ejection seats currently in service cannot autonomously obtain the ejection attitude and trajectory in tests. The research is based on the principle of self-enclosed inertial navigation, with the aid of the overload and angular velocity data collected during the tests, and through low-pass filtering and moving average processing, the quaternion method and the two-interval coning compensation algorithm were used to calculate the attitude and trajectory within the dynamic period after ejection, The posture and trajectory curves of the dynamic period from two 0-0 tests of the X1 ejection seat and two 450 km/h tests of the X2 ejection seat were obtained. Compared with the optical measurement results. The results show that: 1) The two-interval coning compensation method improved trivial effect on the quaternion method, there is no need to consider the influence of the error caused by the rotation of the non-fixed axis after the ejection. 2) For the both 0-0 tests, the main factor affecting the calculation accuracy of the eastern trajectory is the roll angle error. The main factors affecting the calculation accuracy of the northern trajectory are the yaw angle error and the pitch angle error. The main factor affecting the calculation accuracy of the sky trajectory is the pitch angle error. 3) For the both 450 km/h tests, the main factor affecting the calculation accuracy of the eastern and northern trajectory are the cumulative error, the cumulative error has a small effect on the calculation accuracy of the sky trajectory.According to analysis, the errors mainly come from the installation, alignment, data collection and processing process, and subsequent error correction research will be carried out.

Key words: ejectionseat, dynamicperiod, overload, angularvelocity, attitudeandtrajectory