Design theory of stored testing and measuring system and its realization in dynamic data measurement of missile
Beijing Institute of Technology
Stored testing and measuring is a kind of dynamic test technology wherein micro data recording gauge is embedded in the object to be measured in the condition that there is no or allowable effect on it. The information is collected and memorized at the spot in real time. The recording device is recollected and computer is used to process the measured information. The key to realize dynamic stored testing and measuring lies in developing of stored testing and measuring system (STMS) that can work normally in the testing environment and have either no effect on the object to be measured or the effect is in the allowable range.
The definition, character, application field and basic elements are studied systematically. The overall review of research and development situation in home and oversea is given. During Ph.D candidate studying period, the author has presided over the development of data-recording devices used on 60 channels dynamic data testing and measuring (TM) during atmosphere-reentering of intercontinental ballistic missile (ICBM) warhead, intelligent missile blockbox used on dynamic data-recording of certain heavy anti-tank missile flight, anti-warship missile slip track flight fuse data testing and measuring system, cannon shoot missile ball cartridge flight data-recording device, STMS of inner overloading curve of penetrative pill and ball chamber. Based on these experiences the author analyses thoroughly the inner rules of testing and measuring technology and summarize the design concept and design rules in a philosophical view. The design principles that can conduct the
engineering practice of STM are established, which make the design of STMS optimized in a logical and rational way.
The STMS researched in the paper mainly used in the special environment with the following attributes: (1) transient single process; (2)multi-parameter interrelation, strict time-relation and the need of precise measuring simultaneously; (3) analogue and digital information, high range transient signal and micro range slow-change signal exist simultaneously (the range difference greater than four orders and both the amplitude-testing and the process-recording is needed); (4) bad testing and measuring environment, for example, high temperature up to 3000℃, high press up to 1000Mpa, 100,000g strong impact vibration , high rotate speed and strong magnetic disturbance; (5)the measured system is high-technology product with expensive test (up to tens of millions RMB for one experiment); (6) small test space (no disturbance to the tested system is required and effect be smallest); (7) difficult to recovery; and so on.
After systematically studying many of the STMS examples, the design theory and ten microscopical design principles of STMS are presented. They include realizability of working principle, recollectability of testing and measuring data, matching and/or harmonizing, compatibility, environment-adaptability, reusing and calibrationability, flexible design, modularization design, optimizing and trade-off of technology schemes. The conception of state design of STMS is firstly presented. The basic conceptions (for example, STMS state, state variable, state space, state net, state assemble and state chain) are defined, followed by studying of state assemble, establishing of state chain and/or state net design principles and methods. Further, their application scope and typical applications are illustrated. The time power factor theory and
the mathematics description of system state and its transformation are presented.
Considering STMS as an information transmission system, the information transmission model of it is established. The testing and measuring information flow, equivalent information transmission model and noise model are analyzed. From the information transmission view, the similarity between STMS and Shannon communication system is compared to establish the theory basis for studying TM channel by application information theory.
Quantify algorithmic defining information of measured signal that make use of entropy and entropy power has been presented, including TM channel capacity principle, the maxim interinformation principle and information rate distortion principle. Channel capacity of continuous analogue signal TM and anti-disturbance capacity limitation. The relation equation between STM channel transmission information and signal energy as well as TM channel anti-disturbance capacity limitation equation is established. The optimization analogue signal TM channel is presented, based on analysis of channel frequency character and information entropy, the maxim SNR condition of TM channel and the condition wherein both the minim TM channel output waveform and the maxim SNR condition are obtained. In the design of TM channel information the conception of distortion and rate distortion is introduced, moreover, the calculation equation of TM channel information rate distortion function is established.
STMS digital signal TM channels are composed of one or more duality signal channel. In the paper, the digital test channels are synthesized as a combinaiton of “Z” channel and the channel of symmetric disturbed information. The basic channel and channel capacity as well as caculaiton of channel overlap probability are researched. Moreover, the information
channels capacity and the best channels layout of test instruction channels and test data channels are discussed.
Sampling and quantizing are the most important technology in STMS, which is related to information obtaining quality and STM precision. In common sampling TM system, the sampling frequency setup is inclined to be high (especially while the measured object is not known clearly) in order to obtain enough data. Thus, there is much information redundancy. Real time information compression technology must be developed so that more information that is useful can be recorded in the limited memory (reversely, the STMS cost can be reduced since the needed memory capacity is compressed).
According to the attribute of the measured signal, the TM requirement, working environment and so on, the basic problems of STM sampling design are researched. Four STM sampling strategy (uniformity sampling, automatic subsection uniformity sampling, programmable self-adaptive subsection uniformity sampling and self-adaptive sampling) are presented. The algorithm of zero order and one order predictable self-adaptive sampling is introduced in detail. The source of sampling error and the method to avoid it are analyzed and researched.
Two kinds of sampling signal quantizers (uniformity and ununiformity) are presented. The information rate distortion function of the uniformity quantizer and the SNR algorithm are established. The signal capacity and multi-channel information TM principle is researched. The alternative principle of ADC multi-channel transducer is presented.
Information can be stored in magnetic memory dielectric (MMD) or semiconductor CMOS memory. The latter is commonly used in STMS due to complex control, large volume and low anti over-loading ability of MMD.
