Development of new technologies in the field of testing

Testing is an important and effective means to check whether the functions and performance of the test object meet the use requirements and to find problems in time. Generally speaking, testing technology and testing equipment are indispensable in the whole life cycle of product development, production, use and maintenance. They are important means in the product development process, quality assurance tools in the product manufacturing process, and key elements of the product maintenance guarantee system. Testing technology is an important pillar to ensure the "reliability, maintainability, and guaranteeability" of products. It is a technical means for testing, maintenance, and repair guarantee throughout the product life cycle; test instruments and test systems composed of various test instruments are the ultimate embodiment of testing technology. With the improvement of testing needs and the development of applications, especially the development of software and hardware technologies and testing technology means, new technologies in the testing field have developed rapidly in recent years: such as the introduction and application of various new instrument buses, the continuous emergence of miniaturized, synthesized and integrated instruments, the vigorous development of comprehensive and universal automated testing systems and integrated testing and diagnosis systems, and the continuous improvement and application of remote testing and maintenance diagnosis technology, built-in self-test technology, and integrated testing and diagnosis software platform technology. 

Test instruments and advanced test bus technology 

According to the application characteristics of the industry, test instruments can be divided into basic measuring instruments, synthetic instruments, microwave/millimeter wave instruments, etc. In response to the needs of general testing, fault diagnosis, and integrated security systems, the industry has further developed and improved the basic measuring instrument series based on the VXI/PXI/LXI instrument bus, and has further expanded and improved the chassis, controllers, high-speed data acquisition, high-end oscilloscopes, high-speed I/O, edge scanning, microwave instruments, and communication measuring instruments. It has strengthened the research and development of various forms of high-end and integrated instrument products, and attached importance to the standardization, networking, and networking of instrument interfaces. The standardization of instrument drivers brought about by the introduction of the Interchangeable Virtual Instrument (IVI) standard meets the requirements of interchangeability between instruments and provides a basic guarantee for the development and application of a universal test and diagnosis software platform. In response to the development of new-generation radar, communications, electronic reconnaissance and electronic interference, precision guidance and other applications, and to meet the needs of dense, complex and state-changing electromagnetic environment simulation and high-precision measurement and analysis, the related technologies of synthetic instruments and microwave/millimeter wave test instruments have developed rapidly, such as the emergence of wider frequency agile frequency and nonlinear, multi-port, high-power test instrument technologies and instruments, which have realized more parameter comprehensive, modular and integrated testing. The research and application of radio and optical communication network testing technology, infrared testing technology, and software radio technology have also been rapidly promoted. 

The composition of the test system is inseparable from the test bus, and the bus itself has become a major component of the test system. According to the different functions and properties of the bus structure, the test bus can be divided into an internal bus and an external bus. The popular internal test buses in the industry are mainly VXI and PXI buses, which are developed on the basis of VME and PCI computer buses respectively. Although many installation structures and bus definitions are defined, due to the de facto standards of application, the current majority of the structural forms are: VXI uses C size, while PXI uses A size. In the latest version, the bus speed of VXI (V3.0) can reach 160MB/s, while the bus speed of PXI is faster, with a maximum speed of 528MB/s. Another development of PXI to improve transmission speed is to support PCI Express, which is named PXIE bus. It is integrated into the PCI Express bus on the backplane of the PXI bus to meet the fast data transmission requirements of some instrument modules. In terms of application, both buses have been well developed in the test field. The VXI bus defines more stringent clock, power supply, chassis and electromagnetic compatibility indicators, so it is mainly used in high-end test fields, while PXI has developed rapidly in situations requiring miniaturization and fast data transmission between instruments. Another fast bus development is the introduction and application of ATCA (AdvancedTCA) bus, which supports interface speeds of up to 40Gb/s. Domestic instrument manufacturers, represented by Aerospace Measurement and Control Corporation, have fully mastered the development technology of various VXI/PXI bus modular test instruments and formed a series of VXI/PXI bus basic measurement instrument shelf products. Most of the products have indicators comparable to similar foreign products, and some indicators are even higher than foreign products, and can meet the requirements of a wider range of use environments. 

External buses include GPIB, USB, 1394 and LXI. Currently, USB and LXI buses are more actively developed and applied. In miniaturized, portable or laboratory applications, instrument systems with USB interfaces have a rapid development trend; LXI bus, developed on the basis of the widely used Ethernet, is considered to be the first real external instrument bus. It is divided into three levels: A, B, and C. Level A has the highest requirements and can meet the functional requirements of precise clock synchronization and synchronous triggering. It has a unique application space in distributed and large-scale test systems, opening up another world for the application of test technology. 

Automated testing and comprehensive testing technology 

Along with the development of new technologies in the world, the application of information technology and information equipment has become a key way to improve equipment capabilities. Whether it is civil or military land, sea and air equipment, communication systems, automated production equipment, etc., its electromagnetic detection, automatic control, data analysis, data transmission, network communication and other functions are constantly increasing, and the electronic equipment it carries is also constantly increasing. In order to ensure the normal operation of the equipment, the testing and fault diagnosis of these advanced and complex electronic equipment is particularly important. Faced with such a situation where testing and diagnostic tasks are becoming increasingly arduous and complex, over the years, the industry has focused on breakthroughs in single testing technologies while striving to make test equipment automated, universal and integrated to meet the comprehensive testing capabilities of general analog, digital, radio frequency and optoelectronic systems.

The characteristics of the universal test system itself are reflected in the universality of test instruments, universality of software platforms and universality of interface adapters. In the process of universalization and integration based on the automatic test system (ATS), due to the dispersion of investment and management, there are many varieties of ATS, inconsistent system architecture and specialized software and hardware interfaces, which makes it difficult to achieve true universalization. To achieve universalization and integration of test equipment, ATS must be centrally managed and planned. Taking the United States as an example, one of the measures they have taken is to incorporate ATS into the joint technical system architecture of the Department of Defense to strengthen the standardization of ATS; the second measure is to launch the next generation test plan (NxTest) to unify the system architecture of the ATS of the three armed forces. The IEEE-1226 standard is used as the main information framework of the system to share and interact information resources within the test system, between test systems, and between the test process and the external environment (including all aspects of product design, production and maintenance), share TPS and ATS, share diagnostic infrastructure, improve the TPS development environment, and facilitate TPS transplantation; at the same time, the IEEE-1232 standard is combined to make the diagnostic reasoning system compatible with each other and independent of the test process, so as to achieve the transplantation, reuse and sharing of test diagnostic knowledge; the goal of these measures is to reduce the hardware of the test equipment by 2/3, the engineering cost by 2/3, and the TPS development time and cost by 50-70%. The final effect is very obvious, which greatly reduces the scale and investment of test equipment. After the development of the "15th Five-Year Plan", some domestic professional measurement and control manufacturers have made full use of mature modular instrument technology, standard bus technology, general software platform technology and automated test system technology to develop universal and integrated test system equipment that meets military and civilian needs, which has been well applied in the test fields of aerospace, aviation, ships, vehicles, etc. 

Research and standardize the open architecture of multi-level automatic testing, digest and absorb the design ideas of NxTest architecture, realize the requirements of equipment full life cycle testing and cross-platform testing, realize the resource sharing, interconnection, interchange, interoperability, and scalability of information and systems, and meet the needs of general testing such as vertical integration testing. By solving unified specifications and standards and achieving mutual compatibility of ATS in software platform, system interface, and installation structure, we can further improve resource utilization and achieve more universal and integrated testing goals. 

Fault diagnosis and comprehensive support technology 

Testing and diagnosis is to analyze and evaluate the various parameters of the object under test, perceive its characteristics and functions, determine its working or performance status in a timely and accurate manner, and isolate its internal faults, while providing a basis for judgment for maintenance. Fault diagnosis is the highest level of testing tasks. Through system-level and board-level fault diagnosis technology, faults can be located to components, plug-in boards, and even components, and accurate positioning and timely repair can be achieved, thereby greatly reducing the average maintenance time of the system or equipment. 

The comprehensive guarantee technology system includes reliability technology, testing technology, and on-site maintenance technology. Reliability, testability, and maintainability are closely related to the product design process, and testing and diagnosis provide basic data for reliability modeling, reliability analysis, and maintainability modeling. At the same time, requirements for testing and diagnosis are put forward in terms of reliability allocation, reliability prediction, and maintainability prediction. Therefore, it is very important to handle the relationship between them well. In order to meet the needs of comprehensive guarantee of the whole life cycle of products, some institutions have realized the transition from qualitative to quantitative analysis in the design of reliability, testability and maintainability, and in the test and evaluation technology, and have launched a large number of tools for guarantee design analysis and evaluation. Based on the digital design platform, the organic combination of guarantee and performance in the equipment development process is realized, and the integration of various design characteristics is realized based on multidisciplinary design optimization technology. In terms of maintenance technology, information technology, advanced sensor technology, automatic testing technology, fault diagnosis and prediction technology, artificial intelligence technology and other means are used to develop electronic maintenance, virtual maintenance and simulation technologies, and conduct comprehensive detection, prediction and evaluation to improve the speed and accuracy of maintenance. In terms of testing and diagnosis technology, the integrated technology of comprehensive testing and fault diagnosis is further developed and improved, and a standardized architecture of comprehensive diagnosis and maintenance guarantee system is established, which is compatible with the IEEE-1445 standard, and more effective basic technologies such as fault modeling, reasoning diagnosis methods, test diagnosis and information fusion are applied to provide technical means for fault diagnosis at the system level, board level and chip level, and provide more complete technical and product support for comprehensive maintenance guarantee of equipment. With the development of information technology, the latest theories of fuzzy theory, neural network, genetic algorithm and wavelet transform have been applied to the field of fault diagnosis and have achieved certain results. In addition, fuzzy fault tree, fuzzy neural network, expert system based on fuzzy rules and diagnostic methods based on genetic algorithm are all under in-depth research. In terms of maintenance equipment products, many units have developed and applied board-level and system-level comprehensive fault diagnosis system products using expert systems and artificial intelligence methods. Typical equipment includes Teradyne's LASER system, ATEC Series6 system of Aérospatiale, ARIS2000 system of Israel and HTEDS8000 system of "Hua Tuo Electronic Clinic" of Aerospace Measurement and Control Company.   

The new generation of equipment has the characteristics of high intelligence, digitization and busization. Traditional external testing and diagnosis are gradually replaced by internal BIT functions, which has become an important trend in the development of current testing technology. Speaking of BIT technology, it can be traced back to the early 1950s. The United States began to study BIT testing technology and successfully equipped conventional BIT devices on airborne radars in the late 1950s. It was then applied to its fighter F/A-18. In order to improve and enhance BIT performance, foreign countries have integrated artificial intelligence technology, computer technology and semiconductor technology into various BIT levels such as components, circuit boards and systems. In the late 1980s, a new BIT technology based on boundary scan technology emerged and gradually became the main test and testability design technology for new avionics equipment BIT, and was successfully applied in F-22, RAH-66, Boeing 777 and other systems. The new BIT technology is mainly based on the IEEE-1149 series of standards, which mainly includes the definition of board-level and module-level networked test and maintenance buses, and can realize board-level and subsystem-level (unit equipment) BIT for digital and analog circuits. At present, some instrument companies (such as NI, Corelis, etc.) have also developed development tool software and systems that comply with the IEEE Std 1149 standard. Many domestic scientific research units are also working on this aspect, and have achieved certain results and launched some software and hardware products.

Conclusion 

The demand and application of the test field are very extensive. The applied technologies are developing rapidly from analog to digital, from low frequency to high frequency/microwave, from testing to diagnosis, from maintenance to guarantee. The professional vocabulary presented to us, such as instruments, virtual instruments, testing, virtual testing, virtual experiments, diagnosis and maintenance, prediction and evaluation, BIT, etc., are all carriers of new technology development and application in the test field. We are pleased to see that the competent departments, institutes, manufacturers, etc. in the field of domestic testing attach great importance to the planning of test technology development and technological innovation, which will surely have a great promoting effect on the level of test technology and test equipment.