Research On Return Guidance Technology Of Suborbital Launch Vehicle

The initial return phase of suborbital vehicle is the first phase of the return process.The flight environment of this phase is complex and the constraints are strict,which puts forward higher requirements for guidance technology.In this dissertation,the initial return phase guidance technology is studied,which is not fixed in the initial return state and has strict end window constraints.In order to accurately describe the motion state of the aircraft during its return,a three degree of freedom particle motion model is established,and the lift drag characteristics and trim ability of the aircraft are analyzed.Then,the characteristics of constraints in the initial return process are analyzed,and the constraints in the flight process and the end window constraints are transformed into constraints on the angle of attack to design the angle of attack corridor.Due to the limitation of the velocity range in the angle of attack corridor and the wide range of velocity variation in the initial return state of the aircraft,the angle of attack corridor with different velocity conditions can be obtained.Then,according to the relationship between the initial return point and the landing sites,the initial velocity range satisfying the landing site window requirements is obtained by iterating the corresponding velocity of each angle of attack corridor.Then,according to the nominal angle of attack profile of the angle of attack corridor,the nominal altitude velocity trajectory can be designed through the angle of attack profile.Because the initial velocity with the ability to enter the landing field window is not unique,in order to reduce the impact of the initial velocity change on the nominal trajectory,the middle value of the velocity change range of each segment is taken in the design of the nominal altitude velocity trajectory.In order to reduce the range of altitude dispersion,the guidance scheme of tracking altitude is adopted to track the nominal trajectory by adjusting the angle of attack.Finally,in order to verify and evaluate the guidance strategy,this dissertation establishes a three degree of freedom integrated simulation environment in C language environment,and realizes the guidance scheme in integrated simulation.The results show that the guidance scheme proposed in this dissertation can meet the guidance requirements of the initial return phase of suborbital vehicle.