Error Modeling Simulation And Experimental Research On The Roll Angle Measurement For High Spin Projectile Based On Geomagnetic

In order to solve the problem of roll angle measurement for high spin projectile,a novel measuring method based on geomagnetic and the method for precision verification are investigated.Around key technologies of roll angle measurement for high spin projectile,a systematic research is studied in this essay,including the modeling and calibration of on-board measurement error based on magnetic method,the modeling and simulation of the systematic error of roll angle measurement,precision verification of in-flight roll angle measurement,et al.To correct the error of on-board magnetic measurement,a linear calibration model is established where the systemic error of sensors and unwanted magnetic interference(the soft and hard irons)in the vicinity of the sensors are included.To solve the problem of attitude-independent magnetic calibration in flight,a linear method based on ellipsoid fitting is proposed,and then the coefficient matrix of magnetic interference is solved under the assumption of symmetric matrices.Verified by the flight tests of artilleries,the total error of the magnetic measurement after calibration is less than 0.5%.Comparing algebra and geometry ellipsoid fitting method by the data obtained from flight tests,the computing time of the algebra one is shorter and the standard deviation of its error is smaller.In order to assess the accuracy of uniaxial magnetic measurement with ellipsoid fitting calibration under the assumption of symmetric matrices,experiments on the ground three-axis rotary table are conducted,and the results illustrate that the error is no more than 3%larger than that of attitude-independent magnetic calibration method.In order to decrease the experimentation cost and also guarantee the overall resolution simultaneously,a simulation research on the error of the rolling angle measured by geomagnetism method is carried on.As there are two situations(uncontrolled and controlled)in the flight of corrected ammunitions,the auxiliary angle error dispersion models of single magnetic method and satellite combination method are built and analyzed in these two situations respectively.When the projectile is uncontrolled,the Monte Carlo Simulation method is used;while when the projectile is under correction,an instant correction force in a fixed direction,whose starting time and direction are various,is acted on projectiles launched at different elevation and muzzle velocity.In addition,the errors of two rolling angle measurements,which are suitable for whole trajectory domain,are obtained by combining the error of geomagnetic reference angle acquired by simulation and the calibration error analyzed from portable artillery flight tests.Apart from the singularity error zone which located under 1?,the system error of uniaxial roll angle measurement in circumstance of unguided and guided is ±2° and ±10° respectively.When combined with satellite,this error would get decreased to±2°?±5°To assess the accuracy of rolling angle measured by geomagnetism method,a method based on square waves generated by sunray is proposed,and the mathematical model for sun azimuth recognition during exterior trajectory is established.Results based on solar azimuth are proved feasible to serve as a reference for magnetic measurement by the compare between the accuracy of input parameters in these two methods.Altitude angle of central line of field of view as well as measuring time window is designed while solar azimuth recognition model is applied.Dynamic optical measuring experiment is finished on the platform and its results proved the feasibility of parameters designing method.At last,in order to evaluate the effects of geomagnetic calibration,geomagnetic and solar azimuth measurement,measuring modules based on geomagnetic and sunray are designed to complete flight experiments on 155 and 120mm platforms.Four solving methods derived from uniaxial magnetic measurement(band-pass filtering,engineering solution,elliptical and ellipsoid correction)are compared with the optical measuring method.Comprehensive analysis indicates that uniaxial geomagnetic solving method based on ellipsoid fitting has better stability and precision.