Studies On Key Technologies Of Fiber Gyro Strap-down Rotation Inertial Navigation System

Fiber optic gyro has no moving parts, simple technology, wide coverage accuracy, large dynamic range and so on, and it has been widely used in strap-down inertial navigation system. As fiber optic gyro strap-down inertial navigation system omits complex mechanical structures, it has the advantages of simple structure, small size, and low cost. However, as inertial components of strap-down system are fixed to carrier directly, bad working environments vibration environment temperature large range angular and angular acceleration may generate large sytem dynamic errors and component errors. Restricted to the influences of domestic inertial components matrial and processing technology, comparing to traditional mechanical rotor gyro, the accuracy of fiber gyro is low and environment adaptability is poor. So how to improve positioning accuracy and longtime working capability of strap-down inertial navigation sytem are hot issues in current international navigation industry.To reduce the influences of inertial component errors to navigation positioning accuracy of strap-down system and improve positioning accuracy of navigation system, this thesis takes the laboratory investigation fiber optic gyro as the study object, researches on strap-down rotational system. Considering from system desiging level, key technologies and problems of strap-down rotation system have been furtherly studied and analyzed here.First, the subject researching backgrounds and researching significances have been described, the research and development of home and abroad fiber optic gyro strap-down inertial navigation, fiber gyro temperature control technology and strap-down rotation inertial navigation sytem are introduced.Second, by analyzing the influences of inertial positioning paramenter errors coming from inertial components const errors and periodic errors, the principle of inhibiting inertial components errors to system navigation positioning accuracy influences are described. Starting from inertial sytem error equations, the nature of strap-down rotation system self-compensation is analyzed furtherly. Then, inertial components const errors, scale factor errors and fixing errors are as the error sources, error modulation effect expressions of rotation strap-down system are built.Third, analyzing rotation system inertial components key error indexes, according to strap-down system error equation calculation methods, taking inertial components const drifts scale factor errors and fixing errors as error resources, aming at strap-down single-axis rotation scheme, single-axis unidirectional continuous rotation and single-axis positive inversion two typical rotation methods, single-axis rotation system positioning parameter error expressions have been built. In order to realize high accuracy strap-down single-axis rotation inertial navigation system, by positioning parameter error expressions, fiber optic error indexes which can satisfy positioning accuarcy are determined. And the correctness of single-axis rotation system positioning parameter error expressions have been verified by simulation and the error indexes analysis scheme is feasible.Forth, a high accuracy temperature control system is designed, and a general design scheme of temperature control system is given. The platinum resistance is as the measuring component, using constant flow source electrical brige, a new temperature solving method is proposed. When semiconductor refrigerator is used as temperature control componments, environment temperature changing at-10～50℃, it can stabilize working temperature at28-35℃for fiber optic gyro and the method choosing refrigerator type by semiconductor working situation is proposed. And temperature control system model is built by experiment, semiconductor refrigerator control scheme based on BP neural networks adjusting PID controller parameters is designed, environment temperature as neural network input nodes is introduced. In order to verify working accuracy of temperature control system and fiber optic gyro working under temperature controlling, temperature control box evaluation experiment and gyro drifts testing experiments are used here.Fifth, on the foundation of analyzing constant drift modulation effect by single-axis rotation system, in order to compensate const drift completely, principles to be followed when designing double-axis rotation scheme are proposed here. Deriving scale factor error modulation effect expressions by double-axis rotation, building expression principles of angular error induced by scale factor error is proposed. According to proposed principles, double-axis rotation scheme is designed, and the compensation effects of inertial components are verified. When determing double-axis rotation scheme there are some key indexes, such as system rotation time, stopping time and rotating period. And by building positioning parameter error expressions which are motivated by double-axis rotation system const drifts, key technology indexes quantitative analysis method by positioning error expressions is proposed. Furthmore, the correctness of designing double-axis rotation scheme by proposed principles is verified by simulation, and whether positioning accuracy of double-axis rotation scheme by optimizing key designing indexes can satisfy requirements has also been tested.