Optimal Design Theory And Methods Of The Uniform Accuracy Life For Dynamic Measurement Systems

The application of dynamic measurements is becoming more and more extensive with the development of science and technologies, which promotes the research and development of the dynamic accuracy theory. It has been proved in practice that the accuracy of measuring instruments is not always the same and instead it will gradually loss with the time passing by. The accuracy lives of components in a measurement system are not uniform, which will cause the waste of social resources and economic costs. This thesis focused on the development trend of dynamic measurement accuracy theory and the social objectives of "green manufacturing" and did some research on the theory and method of optimal design of dynamic measurement systems based on the uniform accuracy life principle.The main research contents and innovation points of this thesis are:(1) A new method for error decomposition and tracing of dynamic measurements based on Hilbert-Huang transform (HHT) was proposed. This method can decompose dynamic error signals adaptively and overcome the problem of selection of basis functions in the methods of spectrum analysis and wavelet transform. This method was applied to a simulation system and two measurement examples and the dynamic measurement errors were decomposed and traced according to their whole-system error models. The results showed that HHT method is effective in decomposing and tracing dynamic errors.(2) According to the concept of accuracy loss function, the definition of the accuracy loss weight and three forms of representation of it were given. They were absoluate accuracy loss weight, relative accuracy loss weight and the weight of average loss rate. The whole-system error model and regression analysis methods were employed to determine the weight of average loss rate of each component, which provided the basis for the establishment of uniform accuracy life model.(3) Optimal design models based on the uniform accuracy life principle for measurement systems were established by taking the average loss rate as designed variables and considering the range of design variables, the non-uniformity, the accuracy life, and the cost of improvement and so on. Numerical method and optimization theory were combined to solve the uniform accuracy life model, which specified the direction for the improvement of the actual measurement system and the achievement of uniform accuracy life.(4) An experiment system for measuring the accuracy loss data of the inductance micrometer was set up. According to the whole-system accuracy model of the inductance micrometer, error decomposition and tracing based on HHT method was carried out to obtain the accuracy loss data of an inductance measuring system and its components and the optimal design model was presented and solved. Through the improvement of the system and experiments, the uniform design methods of accuracy life were proved feasible and valid.In this thesis, dynamic errors can be decomposed and traced according to the whole-system accuracy model and then accuracy loss functions will be obtained. Optimal design model can be set up in accordance with the uniform accuracy life principle and the optimal design of the dynamic measurement system is realized in the end. The research makes the dynamic accuracy theories and technologies more perfect and practical from dynamic error analysis to optimal accuracy design of measurement systems.