| The performance of inertial navigation system(INS)directly restricts the actual combat effectiveness of weapons and equipment,especially for weaponry like fighters,satellites and submarines which require high reliability and accuracy.In this paper,some key techniques of mechanically dithered laser gyroscopes in redundant configuration and combined configuration INS are studied.The purpose of this paper is to improve performance of the ring laser gyroscope(RLG)inertial navigation system while making further researches on different architectures of mechanically dithered laser gyroscopes through hardware redundancy,software redundancy and combination of different inertial devices.What is more,reverse calibration techniques of three-axis turntable has been studied based on high-accuracy inertial navigation system.Researches made by this paper including 5 main parts:1.Structure configuration analysis of mechanically dithered ring laser gyroscope redundant inertial measurement unit(RIMU).Based on general sensor placement scheme of skewed redundant inertial navigation system,analysis on reliability and cost-effectiveness ratio of RIMU have been made according to sensor output model and placement scheme of IMU.Optimum schemes of device-level redundant system have been proposed based on different redundancy of devices and structure configurations.Aiming at the natural characteristics of the mechanically dithered laser gyroscopes,the redundancy and configuration scheme of RLG RIMU are analyzed.According to the redundant design requirements of power supply,data communication,signal processing and navigation computer of redundant INS,specific design schemes of RIMU are proposed and outputs of prototype are tested.2.Researches on high-accuracy calibration method of RIMU.High-accuracy parameter calibration is the basis of inertial navigation.Considering that devices of RIMU are skewed installed,the calibration parameter modeling of RIMU is different from that of traditional orthogonal system.And with more complex structure of RIMU,it has been difficult to separate errors.Currently both analytical and systematic calibration methods of orthogonal IMU can not be applied in RIMU.Therefore,the calibration error modelings,calibration error excitation method and error estimation method of RIMU are studied in this paper.The RIMU prototype developed by our research group was taken as the object,Kalman filtering methods of systematic calibration scheme based on slave navigation system have been proposed to accomplish high-accuracy parameter calibration.Besides,the static and dynamic positioning accuracy of navigation experiments of the prototype has been tested.The maximum positioning errors during dynamic test are 0.38nm/1h and 1.2nm/3.5h.3.Researches on correlation techniques of single-axis rotaion combined inertial navigation system based on mechanically dithered laser gyroscope and fiber optic gyroscopes(FOG).In order to make full use of laser gyroscopes,the concept of combined system was pioneered.We decided that the laser gyroscopes can be installed in up direction,while the fiber optic gyroscopes can be installed in horizontal plane in order to achieve combined application of different inertial devices.According to the requirements of the combined system,we designed a system prototype,which weighs 10 kg has a volume of 24.5cm?21cm?25cm.Considering of the specific error characteristics of combined system,solutions dealing with dithering problems of mechanically dithered gyroscopes are proposed.Measurements on time delay errors of RLG and FOG are analyzed.Besides,high-accuracy delay measurement of different devices are achieved by adopting analytical delay error measurement and systematic delay error estimation.The navigation performances of prototype under static condition,static-dynamic condition and dynamic vehicle experiment are tested.The maximum positioning error under static condition is 0.876nm/60 h.The maximum positioning error under static-dynamic random roll tests are 1.87nm/48 h and 2.67nm/120 h.The maximum positioning error of vehicle test is 2.3nm/8h.4.Researches on suppression of Schuler cycle oscillation error based on multi-channel delay alignment of software redundancy.As for long-time alignment of high-accuracy inertial navigation system especially those systems which adopt rotation modulation,the Schuler cycle error is the main part of positioning error when the bias of up-direction gyroscope is accurately estimated.Based on analysis of mass data,some systems are figured out that their Schuler cycle oscillation characteristics are highly accurate.This part discusses suppression methods of Schuler cycle oscillation error based on software redundancy.After cycle oscillation error of inertial navigation system is analyzed,methods adopting multi-channel delay alignment are proposed to suppress Schuler cycle oscillation error.The optimization amounts of multi-channel signals and data fusion are studied,while static and dynamic long-time navigation tests on INS are accomplished.5.Research on reverse calibration techniques of three-axis turntable by high-accuracy INS.The interrelationship between angular position(output from turntable)and attitude(output from inertial navigation system)is generated through vector matching.Then verticality between each pair axes of three-axis turntable are measured.Finally the initial attitude of turntable and the real-time attitude are measured according to output attitude from three-axis turntable. |
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