Design Of Atmospheric Pressure Altimeter Based On CAN Bus

Atmospheric pressure altimeter is an important kind of aeronautical instruments, the main function of which is to offer carrier exact altitudinal information. Increasingly, the rapid progress of aeronautics and astronautics technology has make aeronautical instruments becoming more and more intelligent. Economization on energy, lightweight and combined with filed bus has become the dominant technology of altimeter in the future time.Firstly, the paper introduces the concept and the developing trend of the atmospheric pressure altimeter. and then discusses its design requirements on the miniaturization, high accuracy, high reliability and environmental adaptability and the basic direction of the research is been determined. And the paper also discusses the basic principle of barometric height measurement in aerospace applications. According to the standard atmospheric parameters of the Northern Hemisphere, Calculation formula of barometric pressure and Height is been studied and builded. And at the same time, taking into account of a simplified algorithm model of the design of MCU hardware platform. The calculation error was analyzed. Propose the overall design of the high performance hybrid integrated micro controller as the core of the hardware of MSC1201. Then, the hardware circuit and software design of each module of the system are designed and analyzed in detail. The hardware design uses a modular design,and each function module is relatively independent, easy to testing and maintenance and Troubleshooting. Detailed description on the selection of hardware components and circuit design of the system power module, pressure sensor module, Microcontroller module and CAN bus communication module.Then,the design and analysis of the anti-interference and EMC design of the system are also carried out.The software design of the CAN bus atmospheric pressure altimeter is using the Keil C and C code.The software degin divide the software to some different fucntion unit and to achieve the modular standardization design. Introductions about A/D conversion module, pressure signal calibration module, air pressure height solution module and CAN bus communication module are carried on on software design process and methods. Finally,tests are carried on CAN bus atmospheric pressure altimeter engineering prototype in laboratory conditions.Then we compare the results between the testing result and the theoretical value and analyze the error source of the measurement system.In order to meet the altitude measurement of pilotless aircrafts,an intellectual Atmospheric pressure altimeter based on CAN filed bus technology has been developed.Two key technologies study is completed:1.Study the mathematical model of the pressure sensor of PGA309,achieve its fuctions on MSC1201 microcontroller platform and achieve the high accuracy compensation of temperature error and Nonlinear error of the pressure sensor.2.study the relation fuction between atmospheric pressure and standard sea level height,using the least square method and the linear interpolation to achieve the solution algorithm of the MCU,and the error range of the the results is in a reasonable range.The research results of this paper is universal. Having significant reference on the intelligent sensor and instrument design on miniaturization and integration.