Modification method of the infrared attitude measurement model for projectiles based on odd-power functions

•The infrared radiance between the sky and the earth is obtained by simulation.•The inaccuracy of the simplified infrared attitude measurement model is analyzed.•The infrared modified model based on odd-power functions is established.•Semi-physical experiment compared the accuracy of the current and modified models. The attitude measurement method based on infrared is a new type of projectile autonomous attitude measurement method, which has attracted more and more researchers. However, the attitude measurement mathematical model currently used for projectiles is the simplified model after fitting. To improve the accuracy of the infrared attitude measurement theoretical model and the subsequent attitude calculation accuracy, a modified model of the infrared attitude measurement for projectiles is put forward based on the odd-power functions. After analyzing the infrared attitude measurement model for projectiles, the infrared radiance between the sky and the earth at different observation angles is obtained by using the MODTRAN simulation software. And the odd-power functions are introduced to modify the infrared attitude measurement model to approach the infrared radiance curve. Finally, the accuracy of the current and the modified infrared attitude measurement models are compared through the semi-physical experiments, which indicates that the modified infrared attitude measurement model has the smaller Sum of Squares due to Error (SSE) and the Root Mean Square Error (RMSE) of 1.0686 and 0.0612 and the bigger R-square of 0.9985. The results of this study provide the theoretical basis for the reduction of the projectile infrared attitude measurement error from the root.