Engineering Estimation Of Aero-Optics Imaging Deviation Based On Backward Ray-tracing

When the aircraft is flying at high speed,the head generates a compressed gas flow field,which causes the aero-optical imaging deviation of the target image received by the airborne optical system.The imaging deviation of aero-optics is one of the important factors that affect the development of precision guided weapons and equipment.The related research has important military application value.In the study of aero-optics,the calculation and analysis of the imaging deviation can't be separated.In this paper,a typical aircraft is taken as an example to study the engineering estimation of the aero-optical imaging deviation based on the backward ray-tracing.Firstly,a backward ray-tracing method is proposed for aero-optics simulation,which is used to simulate the aero-optics effect.Different from forward tracing,the backward tracing direction is from the internal sensor to the distant target.Along this direction,from the internal sensor tracing followed by the internal gas region,the aero-optical flow field to reach the freestream.The coordinate value,the density,and the refractive index are calculated at each tracing step.A stopping criterion is developed to ensure the tracing stop at the outer edge of the aero-optics flow field.Second,the influence of the trace step on the imaging deviation is analyzed when raytracing calculates image deviations and angular deviations.The Runge-Kutta method is used to complete the tracing.During the tracing process,the quadrilateral mesh interpolation is used.Based on the typical velocity Mach number 3 and attack angle 0 degree,the influence of tracing step size on imaging deviation is analyzed,and a series of typical data about different line-of-sight angles for different height are given.Finally,in order to realize the rapid estimation of the aero-optical imaging deviation in practical engineering,the CPSO algorithm with global search capability is introduced to optimize the parameters in the LSSVM prediction model,and constructed the aero-optical imaging deviation prediction model.In the model,we first use the chaos sequence to initialize the position of the particles to enhance the search diversity.Then use the chaos algorithm to premature convergence judgment and processing.When the algorithm falls into the local extremum,the extreme position of the population is adjusted,the current search trajectory of the particle is disrupted,the particle searches for new neighborhoods and paths,and the probability of jumping out of the local optimum is increased.