Azimuth Scaning Servo System Design Of The Weather Radar On Board

Weather radar on board is one kind of radar, whose basic functions are detecting thunderstorm rain, turbulent flow, hailstone and other meteorological information on airline, watching the landform, barrier under the aircraft, then showing the relevant parameters of object on the screen of sector scanner .The functions of the weather radar azimuth scaning servo system are to drive the radar antenna to scan in sector, detect the target in scaning area and receive the weather information. The performance of radar system is directly influenced by the performance of azimuth scaning servo system. Besides, radar antenna and its servo system must adapt to the requirements of the working environment condition, weather radar system on board should not affects the performance of carrier aircraft or affected by the variety, different flight mode, flight environment of carrier aircraft.A suit of servo system which could drive one type of weather radar to scan in sector is designed in this paper. The control part of this system is made up of PC computer and stepping motor motion control card PCI-1240, The control software which is written by Visual C++6.0 and function library of PCI-1240 could to set and feedback the scaning parameters. This control partment not install on the carrier aircraft, and only for the next environment validating experiments and debugging. The perform module who is made up of stepping motor and speed reducer could provide the output moment which needed by azimuth scaning, its decide the property of all system, so select an appropriate motor and design a steady structure of speed reducer are the core and key of servo system, this paper has designed two kinds of schemes based on different stepping motor and speed reducer, and makes an comparison analysis of there performance, structure and features. The driver circuit which is designed based on integrated driver IC DRV8811 is using the theories of PWM chopping wave for constant current and bipolar drive, this driver circuit could steady the motor phase current to the given value which is decided by sample resistance, so the stepping motor will have good output moment.Besides, the servo system must adapt to the requirement of the working environment condition, so it must to do environment testing for servo system, including vibration test, impact test, acceleration test, high and low temperature test, humid heat test, mould test, salt spray test etc.With the authentication of environment experiments, rational design of hardware and software, servo system which based on stepping and speed reducer of scheme two could accomplish the sector scaning of radar antenna, meeting the requirements of the azimuth scan of weather radar on board. Keywords: azimuth scaning, servo system, motion control card, stepping motor, design...