Research On Ascent Phase Trajectory Optimization Of Hypersonic Cruise Missile

In this paper,X-51A aircraft was the object in the research on ascent phase trajectory optimization problem of hypersonic cruise missile.The needed equations of motion,atmospheric model,aerodynamic model and thrust model for optimization were established.Various constraints of a missile during flight at ascent phase were analyzed.The simulation of ascent phase trajectory optimization was finished using Radau pseudospectral method and sequence quadratic programming method.First,the equations of motion of a hypersonic cruise missile were established.With focusing on longitudinal motion,the equations were decomposed and simplified,then the simplified equations of longitudinal motion of a missile were obtained.Considering the flight altitude span of the missile during ascent phase was from 15km to 30km,based on Yang Bingwei'atmospheric model,the index model of atmospheric density in altitude span from 15km to 30km was obtained by fitting.With aerodynamic data obtained from simulation,various experience fitting models were analyzed and compared,and a aerodynamic model of high accuracy was obtained.Based on pre-existing data,the change rules of I_sp and mass flow rate were fitted,then the thrust model was established.After that,the ascent phase trajectory optimization model of hypersonic cruise missile was established.All of the constraints and the objective functions for ascent phase trajectory optimization were confirmed,and the specific values of the constraints were given.With fixating on the flight corridor during ascent phase,the height-speed climb straightly mode was designed,and its standard trajectory and track trajectory were obtained,then to provide preliminary estimates for optimization process.The trajectory optimization simulation was run with goals set separately as most fuel-efficient and fastest climbing using Radau pseudospectral method and sequence quadratic programming method,and more optimal results were achieved.The optimization results showed that these trajectory optimization methods are effective,and the calculation results are stable,which indicates the complexity and the necessity of ascent phase trajectory optimization.In addition,a hybrid optimization algorithm based on GA?Genetic Algorithm?and SQP?Sequential Quadratic Programming?was proposed in this thesis,which is called GASQP.Compared to GA and SQP,the optimization performance of GASQP is improved significantly.