Research On Longitudinal Guidance Law Of Reentry For Reusable Launch Vehicle

Reusable launch vehicles’ reentry flight range is far and the aerodynamic environment of RLV is complex, thus putting forward a higher requirement for reentry guidance.In this paper, first of all, it is pointed out that the reentry guidance technology is a kind of longitudinal indirect guidance, the guidance process is complex, and the efficiency is low. To solve this problem,a new guidance law is proposed in this paper. Using the angle of attack to achieve the tracking of dynamic pressure profile.Then further research utilizing the pitching angle tracking indicated airspeed profile of the longitudinal guidance law, and verified by simulation.In this paper, firstly, the reentry guidance technology of the space shuttle is studied.For the space shuttle’s reentry guidance uses the lateral roll angle tracking drag acceleration profile leads to lack of guidance of complex.According to the research of aliasing, the dynamic pressure is a low frequency signal, and the response characteristic of the angle of attack is better than that of high frequency.According to the guidance law of the angle tracking dynamic pressure profile, due to the large dynamic pressure, the gain parameters of the guidance law are too sensitive, and the dynamic compaction guidance law is not conducive to the safety of the angle of attack.Aiming at this problem,put forward to substitute the dynamic pressure with indicated airspeed, indicated airspeed and the dynamic pressure is essentially the same but the change more slowly, table speed guidance law research that indicated airspeed guidance performance better. In this paper, the final choice indicated airspeed as longitudinal guidance law of the controlled variable.Studies on the longitudinal guidance command show that angle of attack command and pitch angle command guidance performance differences, this paper points out that the traditional guidance design process will control loop is an ideal approach is flawed, integrated guidance and control simulation results show better performance of pitch angle command guidance. Finally, the space shuttle guidance technology and pitch angle control indicated airspeed longitudinal direct guidance technology of integrated simulation. Results show that the longitudinal direct guidance technology properties is presented in this paper. It has the good value of in-depth study.