Study On Reentry Guidance And Control Method For Hypersonic Glide Vehicle

Based on the requirement for reentry glide and terminal attack of hypersonic flightvehicle, combining with the development trends of advanced reentry vehicle and guidanceand control method, the key technology including multi-constraint reference trajectorydesign, trajectory tracking guidance law, terminal optimal guidance law, bank-to-turn (BTT)coordinated turn control, three-channel band matching and control strategy for singularityare studied thoroughly in this paper. The main contents are as follows:Firstly, the research background and significance are expatiated, the developmentstatus of reentry vehicle and guidance and control technology are introduced particularly,the definition and transformation of coordinate system are mentioned, and the six degree offreedom dynamic model is built.Secondly, considering of the characteristics of reentry flight, the constraints ofreference trajectory design which include path and terminal constraints are put forward.Through converting the dynamic pressure, normal overload, heat rate and qusi-equilibriumglide condition to the relationship of altitude vs velocity or drag acceleration vs velocity,the feasible reentry corridor is published. Based on the reentry corridor of altitude vsvelocity, the reference trajectory is accomplished, which can also meet terminal altitude,velocity and range constraints. The judgment criterion for reference trajectory feasibility ispublished, which takes the realizability of bank angle as a basis. After the induction andsummarization, the standard design flow of reference trajectory and analysis method foraccessibility of the task is proposed.Thirdly, researching on linearization method error with different design controlvariables, a more general linearized model is published. Based on the theory of linearquadratic regulator, the offline and online longitudinal trajectory tracking guidance laws areproposed. Considering steady Riccati algebraic equation, offline guidance law calculatesoptimal feedback gains to correct state error by method of binding in advance andinterpolating real-time. Online guidance law using indirect Legendre pseudo-spectralalgorithm, discretizing continuous state and costate variables by LGL points, produces and updates control instruction sequence periodically, which can make state error minimum.Meanwhile, making use of the flight direction corridor, lateral guidance law will reverse thederiction of bank angle to satisfy waypoints, no-fly zones and terminal course error.Fourthly, the optimal shaping guidance law with terminal position and impact angleconstraints is obtained for diving attack. Through the analysis of guidance law, thecharacteristics of non-dimensional acceleration, velocity and position are got. Utilizing theadjoint method, the non-dimensional miss distance and impact angle error are discusseddeeply, and it comes the conclusion that the guided time needs15times longer than systemlag time at least, which can make sure the miss convergence. Researching on theapplication characteristics of shaping guidance law, the terminal impact angle designmethod is proposed to satisfy the frame angle and available acceleration requirement.Thinking of impact angle of attack constraint for penetration attack, the optimal terminalmultiple constraints guidance law is deduced by introducing time-to-go to the shapingguidance law control weighting matrix, which guidance law can meet terminal position,impact angle and acceleration constraints well. The weighted coefficients of position, angleand acceleration is discussed, the characteristics of non-dimensional miss of position, angleand acceleration are mentioned also.Finally, according to overload control principle, two-loop acceleration yaw-autopilotwith PI compensation is put forward by aiming at minimizing the output when there isdisturbance input based on the analysis of yaw autopilot structure. The convergence essenceof sideslip angle velocity feedback is clarified, and the engineering implementation ofsideslip angle velocity composed by yaw angular rate and gravity and motion compensationis presented, which will improve the missile coordinated turn control ability better. UsingBTT coupling model, the control effect to different three-channel response speed isdiscussed, and the matched band relationship is proposed. The longitudinal and lateralguidance command must be transferred into BTT command for body execution, and theconversion process will produce the roll singularity. The essence of singularity isresearched, the smoothing and limiting of roll command, the relative BTT-90and BTT-180command generation etc singularity control strategies solving longitudinal commandcrossing zero and lateral small command jumping are designed, and the validity of strategies get proved through the mathematical simulation.These studies above can be certain valuable in theoretical research and engineeringapplication for our hypersonic glide-reentry vehicles.