“In the spacecraft dynamic environment test, various dynamic responses of the structure such as acceleration, velocity, displacement, force, sound and other physical quantities are converted into dynamic electrical signals through relevant sensors. , input to the test system, and the test system with logic processing function dynamically collects dynamic signals in real time and processes them later. In the dynamic environment test, the comprehensive test system should have high data collection frequency and large data flow, so it is more demanding to meet the requirements of the system used.
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introduction
In the process of spacecraft development and finalization production, a large number of dynamic environment simulation tests need to be carried out. In the evaluation of the validity of the test and the quality assurance of the spacecraft product, the data acquisition and data processing of the test play an important role. At present, in the field of test systems for spacecraft dynamic environmental tests, the development level of dynamic comprehensive test systems represents a country’s technological leadership in this field. Therefore, it is necessary to develop comprehensive test systems for spacecraft dynamic tests. system.
1. The principle, composition and key technology of the comprehensive test system for dynamic environmental test
1.1 The principle of the comprehensive test system
In the spacecraft dynamic environment test, various dynamic responses of the structure such as acceleration, velocity, displacement, force, sound and other physical quantities are converted into dynamic electrical signals through relevant sensors. , input to the test system, and the test system with logic processing function dynamically collects dynamic signals in real time and processes them later. In the dynamic environment test, the comprehensive test system should have high data collection frequency and large data flow, so it is more demanding to meet the requirements of the system used.
1.2 Main performance indicators of the comprehensive test system
128 channels of A/D synchronous sampling; 4 channels of D/A output; the maximum channel sampling rate is 51.2KSa/s; the channel sampling data conversion precision is 16 bits.
1.3 Composition of Comprehensive Test System
According to the function division, the spacecraft dynamics comprehensive test system can be composed of data acquisition, data transmission, data processing and storage. According to the structural composition, the spacecraft dynamics comprehensive test system can be divided into the following three parts:
(1) Computer software with various dynamic signal testing and analysis functions: random signal analysis, positive spin signal analysis, shock signal analysis, etc.;
(2) Computer host platform and accessories: including various high-performance processors with powerful processing functions and memory, high-throughput computer memory, high-resolution monitors and accessories;
(3) Test and acquisition device of test signal: including sensor, preamplifier and data acquisition system.
1.4 Key Technologies of Integrated Test System Design
The development of a comprehensive test system for spacecraft dynamics and environmental testing needs to be met in the following technologies:
(1) Optimal design, structural composition and flexible configuration technology of dynamic comprehensive test system:
(2) High-speed data synchronous acquisition technology of comprehensive test system;
(3) High-capacity data real-time transmission technology;
(4) High-speed data storage technology;
(5) Various data processing technologies that meet the usage requirements:
2. The architecture of the comprehensive test system for spacecraft dynamic environment test
The purpose of the development of the comprehensive test system for spacecraft dynamics environment test is to engineer the design at a lower cost, shorten the development time of the comprehensive test system, and reduce the risk to a minimum. Therefore, the design of the hardware system must adopt the international best Advanced and mature industrial standards to maintain the compatibility of functional modules and directly absorb the achievements brought by the development of modern science and technology; software design should use a large number of application software frameworks to adapt to changes in system scale and parameters to the greatest extent.
The comprehensive test system of spacecraft dynamic environment test consists of two parts: hardware platform and software system. The choice of hardware platform is determined by the test system structure used. Specifically, the dynamic comprehensive test system structure includes control mode, bus system configuration, distributed chassis structure, multi-bus composite architecture and so on. The software system is the core of the test system, including the software (ie driver, soft panel) operating environment and test-oriented application software.
The integrated test system architecture is the core technology for setting up the test system, including the test system structure, hardware platform, software system framework selection, etc. Choosing a general hardware platform and a general software framework is a good way to establish a general dynamic testing system. The discussion in this paper mainly focuses on the hardware level.
3. Selection of hardware system structure of spacecraft dynamic environment test comprehensive test system
At present, the instrument bus platforms that are relatively mature in technology and widely used in the market are divided into VXI bus and PXI bus.
As an open bus technology, VXI technology reflects the system requirements of standardization, modularization, serialization and generalization. The open structure can realize the sharing of system resources, software resources and hardware resources. The system channel is easy to upgrade and expand, adapt to the needs of various occasions, easily reorganize the system, and can adapt to the development of computer technology and integration technology, adopt the latest achievements of computer technology and integration technology, maintain the advanced nature and compatibility of the system, improve the Accuracy and reliability of system testing.
In addition to many features similar to VXI bus technology, PXI bus technology also has higher data transfer rates, miniaturization, and lower prices.
(Low-end systems are usually more than 10,000 US dollars cheaper than VXI systems, and the price difference between mid- and high-end systems is smaller), while PXI bus has the advantage of being directly connected to the computer compared to VXI bus. However, PXI bus technology has been around for a short time, and it still needs to be improved at the technical level. At the same time, it lacks the full support of the most influential manufacturers in the field of instruments. The variety of products is not rich enough, and there is a lack of strong technical support. Therefore, PXI is currently used. There are still some technical difficulties and risks in the construction of a high-precision large and medium-scale data acquisition system that meets the requirements of spacecraft dynamic environment test using bus technology.
Based on the above characteristics of VXI bus technology and PXI bus technology, through the analysis and research of the bus technology used to build the spacecraft dynamics environment test system at home and abroad, the VXI bus technology is used in this system as the building dynamics integration. In order to reduce the difficulty and risk of setting up the system, the design principle of software independent of the hardware platform should be adopted as far as possible in the design time of the application software system, so as to keep track of the development of PXI bus technology. After maturity and conditions, the dynamic comprehensive test system can be easily transplanted to the hardware platform.
4. Hardware platform design of comprehensive test system for spacecraft dynamic environment test
The hardware platform is the most basic part of the test system structure. To build a test system, a standardized, modularized and serialized design system must be realized. Only by building the hardware platform on a highly standardized and modularized structure can the development cost and system development time be shortened. Ensure long-term availability of the system. The hardware platform of the comprehensive test system for the spacecraft dynamics environment test adopts the structure of the main control computer with dual processors and the VXI chassis to form the test unit. Among them, a zero-slot controller is built in the VXI test bus chassis to manage the coordination and synchronization between the VXI test modules; the main control computer uses the built-in PCI-1394 conversion card, IEEE1394 communication cable, zero-slot controller and VXI test Various modules of the chassis are connected to realize fast data transmission and communication management with the VXI test chassis. During the test process, the VXI bus chassis completes the acquisition of dynamic response data through the A/D converter, and all the collected data is transmitted to the main control computer in real time through the VXI bus and IEEE1394 connection line, and the main control computer completes data processing and analysis, data tasks such as storage and real-time Display.
In order to complete the dynamic comprehensive test requirements, a 32-channel high-speed synchronous data acquisition module AMC2322 is developed in the system, which can realize 4 modules with a total of 128 channels of synchronous data acquisition. The synchronous acquisition speed reaches 51.2KSa/s, and the synchronous acquisition speed does not decrease much. In the case of , the number of channels can be expanded to more than 300. Another module designed is the 4-way arbitrary wave D/A module, which realizes arbitrary wave excitation output, can be synchronized with A/D acquisition, and can be expanded. performance requirements, and also leave room for system expansion.
During the development of the system, the following key technical problems were mainly solved: First, how to save the data of continuous high-speed sampling. The method is to integrate a 64KWORD space FIFO memory on the data acquisition board, which is used to store 32 channels of parallel acquisition data. The module has the function of setting the trigger condition for the reading of the upper computer, that is, the size of the AD acquisition storage space is pre-specified. Once the condition is met, an interrupt will be generated immediately, and the upper The machine quickly completes the batch data reading. Due to the use of FIFO technology, the reading of the upper computer does not affect the data acquisition.
Another problem to be solved is the problem of data transmission, which needs to ensure that the collected data is transmitted to the computer at the required speed. Because the measured data transfer rate of 1394 is 7-8MB/s and the speed is not high, we use 1394 FireWire technology to bridge the test system bus and computer to solve the bottleneck of data transmission. Greater system data transfer capacity.
The third problem solved is the storage of data. A large amount of collected data is poured into the computer, which requires fast storage. Otherwise, the system will not respond fast enough. At present, the general computer hard disk cannot meet the data storage requirements. Therefore, the disk using SCSI technology can quickly store a large amount of collected data. It is stored in the computer, and we optimize the software design to analyze and play back the data that does not need to be processed, which improves the overall acquisition speed of the system.
5 Conclusion
The design of the comprehensive test system for the spacecraft dynamic environment test fully meets the technical indicators required for data acquisition and analysis in the spacecraft dynamic environment test in all aspects, which lays a good foundation for us to develop a large and medium-sized comprehensive test system.
The Links: SKM400GAR12T4 PM100CSE120 SKM200GAL126D
