Guidance And Control Law Design For Missiles With Blended Lateral Jets And Aerodynamic Control

In the engagement against a maneuvering target, it is necessary for an interceptor to conduct maneuvers with large lateral accelerations. In such cases as large speed, high altitude, the response time of the aerodynamic control becomes comparatively larger due to the insufficiency of aerodynamics, which makes it difficult for the missile to establish in time large accelerations necessary for the guidance correction. The introduction of the blended lateral jets and aerodynamic control can effectively shorten the response time of the missile control system and establish large lateral accelerations. For a missile with blended control, there exist two sets of heterogeneous actuators. For such a missile, the key problem in the control design is the distribution algorithm of control commands between the two sets of actuators, which is the main concern of this thesis. Based on the research on the control design, guidance law design is investigated.First, nonlinear programming problems and their solving algorithms are reviewed. Specifically, sequential quadratic programming(SQP) algorithm is discussed in detail, which is to be applied in the sequel to the control design. In applying SQP algorithm to a nonlinear programming problem, the original problem is first converted into a SQP sub-problem, and the equivalence of the original problem and the sub-problem is proved. Then global convergence and hyper-linear convergence are justified. The analysis is conducted on the so-called Maratos effect, as well as on the counter measures against the effect.Second, for the aerodynamic control mode and the blended control mode, the respective closed-loop controllers are designed. For a missile with typical configurations, the attitude dynamic models for both control modes are constructed and simplified. Then the control design problems for both control modes are transformed into optimal control problems with time and terminal state constraints. The optimal control problems are solved using the previously mentioned SQP algorithm. The obtained open-loop controllers are used in receding horizon model predictive controls to implement the closed-loop control laws. The implementation provides for the closed-loop systems the robustness against uncertainties and the attenuation of external disturbances.Third, guidance law design is discussed for the missile with blended control. Planar relative motion model is constructed for the missile and its target. The maneuvering acceleration of the target is estimated using an extended state high-gain observer and then is used in the augmented guidance law to compensate for the maneuvers of the target. The acceleration commands issued from the guidance law are implemented by the control system of the missile. The switching strategy is designed to switch the control between aerodynamic control mode and the blended control mode.Numerical simulation is conducted for all the designed guidance law and control laws. The simulation results justify the feasibility of the design.