Design And Implementation Of The Aerial Atmospheric Parameter Testing System

The aerial atmospheric parameter testing system is used for the calibration of air data computer by supplying gas with cerain accurate pressure. This paper has analysed the function of the system, built the system control core with an industrial tablet as the upper computer controller and an ARM microprocessor as the lower computer controller, designed the scheme of the entire system including the implementation of both hardware and software, realized the construction of the physical system, successfully applied the testing system to the production of certain airplane.First of all, this paper analyses the function of the aerial atmospheric parameter testing system, then proposed the design scheme of the system based on the previous analysis. The system consists of three levels: the upper computer level, the lower computer level and the sensing and executing level. This paper selects an industrial tablet as the upper computer to achieve the control system’s monitoring interface based on the LABVIEW development platform, chooses an ARM microprocessor for the lower machine to achieve the mainly control logic and adjusting of gas pressure based on the C programming language and designs the power supply module, relays module, PWM module, RS232 module and the adjustable voltage output module, builds the sensing and executing level with the pressure source, gas storage part, gas purification devices, pressure control devices and gas consumption part. The fuction of the upper computer level is to generate and transmit control commands to the lower level. The lower computer level is responsible for converting the control commands to control signals, then sending it to the sensing and executing level which is the final executor of the control system. This level operates according to the control signals and exports gas with cerain accurate pressure, provides feedbacks of the gas pressure for the upper computer as the decision-making basis.According to the overall scheme, this paper describes detailed analysis and designs of hardware and software around the specific realization of the system. The hardware design includes the lower electromechanical circuit board design and processing, the component mounting box design and processing, selections of the sensors and the industrial tablet. The software design includes the HMI layout, the control procedures and the bottom control program.To get high-precision gas pressure is an important and difficult part during the system design process. This paper mainly makes some tries in the following aspects to achieve this goal: First, analyze the relevant principles of gas sensors then choose one with precision as high as possible. Secondly, take account of the gas system’s inherent characteristics and select pneumatic components with high precision and low cost. In addition, minimize the intermediate control links to avoid introducing more systematic errors and combine the intelligent control with the classic PID control algorithms to improve the control efficiency and accuracy in the system’s control process.The aerial atmospheric parameter testing system designed in this paper, after installation, has been put to use in the production of a certain model aircraft, running well, stably and reliably. At last, this paper provides a brief introduction for the system’s operating status and analyses the pressure controlling results. The pressure control accuracy meets the design objectives very well.