Research And Design On Versatile Automatic Test System For Low Frequent Equipment Of Military Aircraft

With the development of information technologies and electronic technologies, more and more electronic devices are used in military materials. On the one hand, these advanced and complicated devices will greatly improve the effectiveness of military materials; on the other hand, they will need heavy test and diagnosis in support jobs. Therefore, automatic test system (ATS), one of the important support device of military devices, is attached more and more importance.At present, test system in China Air Force is at the discrete and manual or semiautomatic stage of tester development, a few materials have their special test systems, existing a great gap between the advanced ATS such as the U.S Army CASS designed in 80's, last century. The U.S Army started its next generation ATS plan (NxTest) again in 1996, which brought the ATS into Department of Defense Joint Technical Architecture, the newly-developed LM-STAR saves more development cost and maintenance cost, leading too much in this field. ATS development for China military aircraft meets great challenges that we can't import ATS from advanced countries such as U.S, neither do we have enough experience to develop it. Therefore it is indispensable to research and design versatile automatic test system for low frequent airborne equipment of military aircraft in order to push military support devices construction in'Integration, Automation and Miniaturization'because military aircraft low frequent equipment is large in quantities, distributes in all specialties and affects too much to flight safety, because developing versatile ATS for low frequent airborne equipment is of high difficulty but lower cost and may adopt advanced technologies from U.S army and because the research achievement can be the good example.The dissertation, taking low frequent equipment of military aircraft for example, designed and developed the versatile automatic test system for low frequent equipment of military aircraft by using open system design theories, applying the corresponding international standards and specifications and considering our practical situation. This system is mainly designed for testing low frequent equipment of military aircraft at DC～100kHz and for test support at organizational level for different type of aircraft in the same aerodrome.Selection of test resources is the key for designing versatile ATS. By comparing the current four types of test apparatus buses, modularized apparatus based on PXI bus are determined as the main test resources to acquire better accuracy, stability and reliability of signal processing. By using as many as possible modules confirming to IVI specification and packaging the general functions for non-IVI modules into the dynamic libraries to enhance interchangeability and reduce the reprogramming because of replacing different modules.Versatile automatic test system features at general test interfaces. In the dissertation, external connections are used between swithing system and test equipment, i.e., switches and test equipment are connected as required in test unit adapters. Doing this may increase the interface plugs but will have better versatility and openability. To specify the test unit adapter design, signal interface unit with 10 modules is used to connect ATE and adapter, signal type of each module is defined and the general design for adapter is done according to numbers of test equipment and switching system.Many units are needed to be tested because this ATS is used for low frequent airborne devices of different types of military aircraft and their specialties. To decrease the programming and improving the test program developing and getting openability of software environment, open and commercial software is chosen to establish uniform test management environment. Using MAX to manage IVI instruments, using Switch Executive to manage switching system according to unit under test and using TestStand as the basis of developing program, managing the test program at levels by specialty, unit under test and test items of the same aircraft and establishing uniform test repots and data database.The system is an open system which enables technical personnel with certain developing ability to easily develop the test program for the unit under test. Therefore, focusing on designing test sequence file, basic rules for test program development is clarified and autoloading of stimulating signal is solved to specify test development at a higher developing quality and efficiency.Environment adaptive design is done because of the unpredicted need from the organizational level. The system can work at -20℃～50℃by using heating unit and choosing KVM set at wide working temperature; it has a good vibration-resistance and impulse-resistance by using vibration-debating apparatus case and fixing the connectors, breakers and switches with glue and replacing mechanical hard disk with electronic one.As mentioned above, the ATS for low frequent equipment of military aircraft is finally designed by commercial software and hardware. It has a good signal characteristics to get better accuracy and stability; a good openability to easily extend it for high frequent equipment of military aircraft by adding essential hardware resources; a good versatility to test different unit under test by following the test steps and designing simple test unit adapters; easy to use because the test program is the same as the test steps; a good supportability to lower maintenance cost and maintenance delay time.