Research On Adaptive Augmenting Disturbance Rejection Control For Launch Vehicle

Launch Vehicle is an important tool for a country to carry out space exploration.At present,major aerospace countries in the world are stepping up the development of a new generation of launch vehicle to occupy the commanding heights of the space industry and further improve their comprehensive strength.In order to meet the design requirements of the control system of the new generation launch vehicle,this paper carries out th e research on the adaptive augmented disturbance rejection control technology of the launch vehicle,and fully draws lessons from the design experience and analysis methods of the traditional launch vehicle control system.The modern control theory is used to design the augmented control module,so as to improve the adaptability of the rocket control system to the complex flight environment such as disturbance,parameter deviation and elastic vibration.Firstly,this paper investigates the development statu s of advanced launch vehicles at home and abroad and the typical advanced control methods of launch vehicles,and focuses on the investigation,analysis and summary of the adaptive augmentation control methods in NASA space launch system.On this basis,th e research content and interrelationship of each chapter of this paper are given.Then,under the framework of the traditional Newton-Euler method,the mechanical characteristics of the launch vehicle are analyzed,the mathematical model of the launch vehicle rigid-elastic coupling and the elastic vibration model are established,and the control model is established by using the small disturbance linearization method.Based on the traditional frequency domain design method,combined with the amplitude margin and phase margin constraints,the PD controller and correction network are designed to meet the basic control requirements.On this basis,an adaptive gain adjustment module is designed to adjust the forward gain of the control system,and the mechanism and design principles of the reference model,high and low pass filter and adaptive law in this module are given.The simulation results show that the adaptive gain adjustment module can significantly improve the control ability of the rocket control system in the face of parameter deviation,disturbance and elastic vibration frequency deviation.The disturbance compensation module is designed based on the disturbance observer method to realize the fast and accurate observation of the disturbance without overshoot,so that the control performance is further improved by introducing compensation control instructions.The simulation results show that the disturbance compensation module can improve the attitude control accuracy of the rocket when the parameter deviation or control gain decrease.Finally,in order to meet the control requirements of the launch vehicle to reduce the aerodynamic load in the strong wind and high dynamic pressure area,the active load shedding module is designed based on the overload feedback method.Based on certain engineering assumptions,the active load shedding control law is derived by using the Lyapunov method,and the switching function is introduced to realize the smooth switching between the load shedding attitude angle comm and and the guidance attitude angle command.The simulation results show that the active load shedding module can reduce the aerodynamic load of the launch vehicle when it is disturbed by shear wind in the high dynamic pressure area.