Adaptive Finite-time Guidance Method For Hypersonic Gliding Vehicles

Hypersonic gliding vehicles can fly in large space at extremely high speed. These characters endow the vehicle with great commercial and martial values. However, motion of the vehicle is with nonlinearity, close coupling. And it’s states change fast in large domain and affected by various constraints and uncertainties. These bring lots of difficulties to guidance. This dissertation focuses on gliding guidance and precise guidance of hypersonic glide vehicles. An adaptive finite-time guidance method considering uncertainties is proposed. The method is capable at handling the above complex motion characters and is easy for guidance law design. Meanwhile, multi-constraints are considered and high guidance precision can be achieved under uncertainties. Main contents of this dissertation are as follows:Considering guidance problem of the vehicle can be transformed to a control problem of linear systems with disturbance, a new finite-time linear control method and a finite-time linear extend state observer (FT-LESO) are proposed. They are theoretical foundations of the researches on guidance method. Under both state feedback and dynamic output feedback conditions, finite-time linear control method is researched. An analytic relationship of controller parameter, convergence speed, and settling time is obtained. It can guide online design of a controller. To observe the disturbance, a FT-LESO is established. An analytic relationship of FT-LESO’s parameter and convergence speed, settling time, steady value of observation error is obtained. Using the relationship to FT-LESO design, it can achieve rapid and exact disturbance observation, which is desired for disturbance compensation.For nominal trajectory generation with uncertainties and multi-constraints in gliding guidance based on nominal trajectory, a three-dimensional nominal trajectory generation method is proposed with adaptions to variation in model parameters and inflight alteration of mission. Using the method, a multi-constrained three-dimensional nominal trajectory can be generated autonomously and rapidly. It adapts to the missions with large-crossrange and has good potential to be performed onboard. Considering variation in model parameters resulting from uncertainties, nominal trajectory is generated onboard based on online estimation of the parameters. It ensures the method adapts to the condition with variation in the parameters. Considering altering target in flight, nominal trajectory is generated onboard based on updated information of the target. It ensures the method adapts to the condition with inflight target alteration.For trajectory tracking control with uncertainties and control constraint in gliding guidance based on nominal trajectory, an adaptive finite-time trajectory tracking control method is proposed. The disturbance resulting from uncertainties is observed by disturbance observer. And by disturbance compensation, control performance is improved. A tracking control law for longitudinal trajectory tracking is designed based on finite-time control. The parameter in the control law is adjusted online to enforce observation of control constraint and acquire good tracking performance. A bank-reversal logic is used to regulate heading error. A terminal heading error regulation method is proposed to reduce the large terminal heading error resulting from uncertainties, and improve guidance precision.For precise guidance under uncertainties and multi-constraints, an adaptive finite-time precise guidance method is proposed with the consideration of uncertainties. Utilizing finite-time control method, longitudinal guidance law and lateral guidance law are designed. The disturbance resulting from uncertainties is observed by disturbance observer, and is compensated in the guidance laws to improve guidance precision. The patameters in the guidance laws are adjusted online according to flight states and remaining time. By the adaptive online adjustment, attack angle, slide angle, and field-of-view of seeker can observe constraints. Moreover, line-of-sight angles and their rates can converge to desired values at termination, terminal constraints can be observed and high guidance precision can be achieved.The proposed guidance method is demonstrated by numerical simulation under various conditions. Simulation results indicate the proposed method adapts to the missions with stationary target and the missions with inflight target alteration. Mul-tiple constraints on flight process and termination are observed. And high guidance precision is achieved under various conditions with uncertainties, including varia-tions in atmospheric density and aerodynamic parameter, unknown acceleration of target, and unmodeled dynamics. The proposed guidance method is effective and achieves higher guidance precision than the methods in literatures. Investigations in this dissertation can provide theoretical foundations for the guidance method re-searches of relevant vehicles.