Constrained Guidance And Control During Hypersonic Reentry Flight

The guidance and control during hypersonic reentry flight,as a difficulty and key point of hypersonic technology,is crucial to the development of hypersonic vehicle(HSV).However,the hypersonic reentry flight is faced with multiple constraints such as the input constraint of the actuator,the process constraint,the terminal constraint and the path constraint in the reentry process.In this paper,the attitude control and reentry guidance of hypersonic vehicle under various constraints,as well as the joint design of reentry guidance and control are studied.Firstly,this paper gives a complete modeling process of hypersonic reentry mathematical motion equation,as well as the aerodynamic model and actuator model involved.Then the later simplified attitude control model and reentry guidance model are obtained.Then,the attitude control problem of HSV with actuator amplitude and rate saturation is studied.So,an integrated control model including actuator state and flight attitude is built,and the Backstepping control method is employed to design the basic control law.In order to deal with the problem of "dimension explosion" residing in Backstepping method,a new kind of polymerization filter is adopted.At the same time,a new disturbance observer is provided to estimate the model uncertainty in the modeling process.Then,aiming at the problem of input saturation of actuators,this paper designs a new compensation feedback auxiliary system to generate fast compensation signals to ensure the tracking performance of command signals.Finally,Simulation results show that the proposed algorithm is effective and the performance is improved.Then,this paper mainly studies the reentry guidance method of HSV with geographical constraints,such as no-fly circle,and designs the reentry guidance law based on the predictive correction algorithm and the constraint optimization method with no-fly circle.So,the reentry guidance equation of three degrees of freedom was firstly constructed,and the constraint of the reentry process was converted into the reentry corridor of the altitude-velocity profile.Then the reentry longitudinal guidance law and lateral guidance law based on the HSV energy were designed.In order to solve the constraint problem with geographical constraints such as no-fly circle,this paper presents a guidance technology of online track angle and inclination angle,and gives a dynamic adjustment scheme as supplement.The simulation results show that the proposed algorithm is time-efficient and effective,and this algorithm can be calculated directly online.The calculation amount is similar to that of traditional guidance law design.Finally,this paper mainly studies HSV's six-freedom trajectory tracking algorithm and control law,and realizes the joint design of guidance and control.In order to plan the re-entry nominal trajectory based on the constrained predictive correction method mentioned above,the longitudinal trajectory guidance law based on the high order sliding mode and lateral guidance logic are established in this paper.Then,the Backstepping nonlinear controller of attitude system was designed to guarantee the quickness and precision of HSV attitude angle tracking,and the guidance system and attitude control system were effectively merged.Last,Monte-Carlo simulation of the standard case and the no-fly circle case shows that the designed six-DOF guidance and control law has good trajectory tracking and strong ability to overcome model uncertainty.