Design Of Guidance Law With Impact Angle And Time Constraints

In modern warfare, it not only requires missiles to be capable of attacking the target with a minimum miss-distance and a desired impact angle, but also hopes that it can attack targets with desired impact time.This is also the basis of saturation attacks with multi-coordinated missiles. Thus, to study guidance law with impact time and angle constraints has an important significance for the progress of guided weapons technology and the development of guidance law theory. So the article takes further research on the method of guidance law with impact angle and time constraints.Firstly, in zero-effect collision triangle, using the optimal control theory, we deduced the guidance law with impact angle constraint. The guidance law can adjust the terminal overload by adjusting the weighting factor so as to make overload concentrate on the early stage of the flight as far as possible. Thereby it can reduce the demand of overload at the end of the trajectory. It can be seen that the guidance law has strong practicability.Secondly, it introduces the sliding mode control theory and proposes a guidance law with a desired impact time constraint based on sliding mode control. The guidance are derived under two time estimate, namely the traditional time estimate and improved time estimate. The guidance law can not only meet the impact time requirement, but also has strong robustness.Finally, the article designs guidance law with a desired impact time and angle constraints through taking the angle control as the main line of switch. In the first stage, we adjust the angle, then adjust time when the angle reaching a reasonable range. At last after the time adjusts to a desired value, modifing the angle in a small range. In theory, the guidance law enables the missile to have a greater angle range.