Research Techniques Of Instrument Based On Integrated Sensors

With the gradual enhancement of opening the low-altitude airspace, the better future of rapid development of general aviation is coming. The safety of general aviation aircrafts is of great importance to the development of general aviation. Due to the characteristic of general aviation flight and the cost of genral aviation aircrafts, the instruments equipped by general aviation airctafts should be low cost, high reliability and realtive high precision. Therefore, the development of integrated sensors instruments with such characteristics is the major content for general aviation aircrafts.In this thesis, the altitude and heading instrument with integrated sensors are the studying objects. With the error modeling and the error compensation of the altitude measurement and heading measurement, the multi-sensors data fusion algorithm of altitude sensors and heading sensors, the altitude and heading integrated sensors instrument is investigated. The major contents and the achievements are summarized as belows:1 Analysis and research on altitude and heading measurement of GPS. The component of the GPS is simplily introduced. The theory of measuring the altitude and heading of GPS are explicated systematically. The error sources and the error characteristics of the altitude and heading measurements of GPS are analized deeply. The basis for the study of integrated sensors instruments in consequence is settled.2 Research on error modeling and compensation of the barometric altitude measurement. The technique method to measure the barometric altitude is introduced. The main error sources, the output error of pressure sensor and the theory error of barometric altitude, affect the measurement precision of barometric altitude in general aviation aircrafts are indicated. The error model of the silicon piezoresistive pressure sensor is established by the fitting of the curve surface to the calibration data. The output precision of the pressure sensor is improved. The problem, that the standard barometric altitude is not compatible to the altitude measurement of the general aviation aircrafts in conncetion with the low altitude. The barometric altimeter theory error model by Taylor expression is established. The precision of absolute altitude measurement of the barometric altitude is improved. The algorithm to measure the relative altitude of barometric latitude is proposed. And the precision of the relative altitude measurement is improved.3 Research on error modeling and compensation of the magnetic interference in magnetic heading measurements. The technique method to measure the magnetic heading is introduced. The theory and error compensation of static magnetic interference to magnetic compass are analyzed. The theory of dynamic magnetic interference to magnetic compass is analyzed deeply. The physical concept of the differential magnetic compasses (DMC) is proposed. And the magnetic heading system based on DMC is designed. The influence mechanism of the dynamic magnetic interference to DMC is investigated systematically. The dynamic magnetic interference model and error compensation algorimth based on DMC is proposed. And the improved algorithm is proposed as well. The effect of the error compensation of magnetic interference to compass is improved. And the precision and reliability of magnetic compass is improved within the dynamic magnetic interference environment.4 Research on data fusion technology of the altitude and heading instrument with integrated sensors. The structure of the altitude and heading instrument with integrated sensors is proposed. According to the complementary error characteristics between barometric altitude and GPS altitude, magnetic heading of DMC and GPS heading, the data fusion technology of integrated altitude sensors and integrated heading sensors are investigated respectively. The mutual calibration algorithm between barometric altitude and GPS altitude is proposed. The error of GPS altitude is calibrated adaptively with the merit of the high precision of the relative barometric altitude in short term. And the precision of the GPS altitude is improved. Based on the several order total differential model, the barometric altitude theory error is calibrated initially with the least squares algorithm and the GPS altitude information. The problem is overcome that the precision of barometric altitude is getting worse when time elapse or the environment changes. The relative barometric altitude is introduced into the adaptive information sharing algorithm of federated kalman filter (FKF) of barometric altitude and GPS altitude. And the data fusion of barometric altitude and GPS altitude is achieved. The recognition parameters of dynamic magnetic interference, based on DMC is proposed with the analysis of the dynamic magnetic interference data, is proposed. The classification algorithm of least squares support vector machine (LS-SVM) is introduced. The recognition model of DMC dynamic magnetic interference based on LS-SVM classification algorithm is established. The effective recognition of DMC dynamic interference is achieved. Further more, the recognition of DMC dynamic magnetic interference is introduced into the adaptive information sharing algorithm of federated kalman filter. And the data fusion of DMC magnetic heading and GPS heading is achieved.5 Development of the prototype of the altitude and heading instrument with integrated sensors. The input unit of the altitude and heading instrument with integrated sensors is designed. The prototype of the altitude and heading instrument with integrated sensors based on ARM 11 processor of S3C6410 is developed. The required function of the embedded developing platform is analyzed. The hardware circuit of embedded developing platform is designed. The transition of the operation system of the embedded linux, of the lib of the third party, and of QtE is achieved. The driver of the hardware interface is achieved. The synchronization design of the input of the instrument with integrated sensors is implemented. The real-time requirement of the system is improved by the research of the high resolution clock. The software frame of the embedded developing platform is designed. And the application software is achieved.6 the experiment of the altitude and heading instrument with integrated sensors. The experiment platform of the instrument with integrated sensors is established. With the help of the purple mountain ropeway and the overpass, the altitude and heading analog experiments of the instrument with integrated sensors are achieved respectively. The performence of the altitude and heading instrument with integrated sensors is verified. And the requirement of general aviation is satisfied.