Improved ignition strategy of trajectory control direct force during terminal guidance

In order to improve the hit accuracy, the direct force is usually used in the terminal guidance of air defense missile in the upper atmosphere. Under the work mode with constant direct force, the hit accuracy was directly decided by the time and direction of the ignition.At present, common ignition logic can not give full play to the correction effect due to the low accuracy of miss distance prediction and ignition direction estimation.To this end, the ignition strategy was improved from the following aspects.First, for the inherent characteristics that line of sight(LOS) angle is usually divergent during the terminal guidance, a new method was proposed to improve the accuracy of miss distance prediction by employing the changing trend of LOS angular rate; Second, considering the practical constraints that the working time of the direct device is limited, the estimation accuracy of correction ability of direct force was improved by increasing the correction term about residual speed; Third, the original ignition position method using LOS angular rate was modified to use the residual required overload. Theoretical analysis shows that the method proposed can advance the ignition time compared to the traditional method.Six degree of freedom (6-DOF) simulation was carried out using different maneuvering targets.The results show that the new method can significantly reduce the miss distance compared to the original method in large target maneuvers, while almost the same in small maneuvering.