Research On Non-disassembly Calibration Method Of Aircraft Inertial Components

As the reference information source of flight control,inertial devices on aircraft have an important impact on the accuracy of aircraft navigation guidance and control.Due to manufacturing,technology,production and processing,inertial devices inevitably have the phenomenon of measurement error parameter drift in the long-term use process,As a result,the accuracy of inertial devices will not meet the system performance after long-term storage or use.At present,the general solution to this problem is to regularly send the inertial devices to the laboratory turntable for calibration.However,for many products delivered to users,it is unacceptable to regularly remove and calibrate the inertial devices from the products,and then reinstall and debug them after calibration.Therefore,in recent years,the "three self" inertial group has been developed to solve this problem,but due to its cost and volume conditions,the "three self" inertial group has not been widely used.Strapdown inertial units are still used in a large scale and in large quantities.Therefore,it is necessary to study the disassembly free calibration method for strapdown inertial units.The goal of the disassembly free calibration method of strapdown inertial unit is to obtain the values of various coefficients of the error model of strapdown inertial unit,which can be regarded as a parameter identification problem in the excitation environment.This kind of problem can be solved by the design of algorithm.Based on the above analysis,the focus of this paper is to design a method of motion excitation for strapdown inertial unit without disassembly,and how to calculate various error parameters.The main research work is as follows:Firstly,the error mathematical model of strapdown inertial unit is studied and analyzed,and their error mathematical models are listed for optical fiber gyroscope and mechanical flexible gyroscope and quartz accelerometer,which are widely used in practice.For the influence of error parameters on accuracy in the error model,various parameters are simulated and analyzed by using the method of static navigation calculation,and the main error parameters affecting accuracy are obtained.Secondly,the overall technical scheme of "high-precision inertial group(main inertial group)+ strapdown inertial group to be calibrated(sub inertial group)" is determined,and the relevant transfer alignment equation,"speed + attitude" matching equation and "specific force" matching equation are established.Based on the motion performance constraints of the excitation assembly,the observability of error parameters is analyzed,and the effect of each motion excitation on parameter identification is simulated,and then the disassembly free calibration process is designed.Finally,under the test conditions of turntable and excitation assembly,the disassembly free calibration process of strapdown inertial unit is comprehensively verified.The test results show that the designed disassembly free calibration method has good results.To sum up,taking the actual performance characteristics of the excitation assembly as constraints,the paper determines the overall technical scheme of "main inertial unit + sub inertial unit",establishes a detailed inertial unit error model,velocity error and misalignment angle equation,designs the excitation motion profile and vertical profile of the main sub inertial unit,and carries out the ground test of the excitation assembly.The test results verify the effectiveness of the calibration method.