Active disturbance rejection control method on load relief system for launch vehicles

Load relief control technology is studied for launch vehicles flying across the strong wind area. First, load relief controllers based on angle of attack feedback and accelerometer feedback were calculated, and limits of these methods were analyzed, thus an improved active disturbance rejection controller (ADRC) based on informed research was introduced into the flight control system. On the one hand, the error which was observed by status observation was introduced into the ADRC loop. On the other hand, by calculating the wind load impact on the control system, it improves the control law in ADRC and proves that aerodynamic load can be restrained by ADRC, and the method to select the gains in governing equation in the improved control law was given. At last, taking a liquid launch vehicle as an example and considering the elastic vibration and sloshing, load relief effect was analyzed with different methods. The simulation results show that after the improved ADRC method is introduced, the flight control system enhances the ability to reject disturbance, and expands the boundary when choosing a gains in the control law. With the disturbance compensation and proposed control law, the effect of the load relief system on the launch vehicle was greatly improved. This method has a great value in engineering application.