| Aiming at the long-existed quality problems of China electromechanical products,such as poor accuracy,short precision life,large fluctuations in performance,frequently failing and so on,in this paper,a set of key quality characteristic analysis,prediction and control methods based on Meta-action Unit for electromechanical products was proposed,which provided theoretical and technical support for guaranteeing the complete machine's quality essentially.With electromechanical products setting as the research object,system definition and comprehensive modeling of Meta-action Unit as the basis,prediction and control of Precision,Accuracy Life,Performance Stablility and Reliability four key quality characteristics as the core,the complex large system research method of “Decomposition-Analysis-Synthesis” was adopted to study the key science problems of Meta-action Unit's definition and modeling,key quality characteristic formation mechanism,quality characteristic fusion and control mechanism,and also the complete machine's coupling and decoupling technology,predition and control modeling based on Meta-action Unit,etc..CNC machine tool was taken as a typical example to finish the theory verification and application.The concrete study context includes five main parts:(1)The definition and modeling of electromechanical product Meta-action Unit.Firstly,the product quality control strategy based on Meta-action Unit was confirmed;the structural decomposition method of “Function-Motion-Action” was introduced;and electromechanical product Meta-action Unit was defined and classified systematically;then the complete machine's quality characteristics were mapped to the Meta-action Unit's by FMA tree;also some domestic machining center's APC was taken as an example for the function analysis and structural decomposition,with the whole machining center's FMA tree shown.Secondly,by the analysis of Meta-action Unit's working process and key parts' performance degradation process,the generalized operator model of Meta-action Unit and the reliability model based on quality degration were obtained,and then models of Meta-action Unit were established from the kinematics and dynamics angle.Thirdly,based on the analysis of uncertainty concept and uncertainty factors,the difinitions and models of Meta-action Unit's two kinds of quality uncertainty,“Gradual Uncertainty” and “Sudden Uncertainty”,were given.And quality fluctuation and error transfer were also analyzed and modeled.(2)The key quality characteristic formation mechanism study of Meta-action Unit.Firstly,the quality characterization technique of Meta-action Unit's life circle was researched,and the key quality characteristics were extracted using the scientific and effective model intergrated by Quality Function Deployment,Failure Mode,Effects and Criticality Analysis,and Fuzzy Theory.Secondly,The formation mechanisms of Meta-action Unit's four key quality characteristics,Precision,Accuracy Life,Performance Stablility and Reliability,were studied deeply;and indexes of each key quality characteristic were extracted from kinetic angle,while Meta-action Unit's indexes of geometric precision,kinematic precision,accuracy life,dynamic tracking error,SNR,vibration,clearance,reliability,and reserved coefficient of reliability,etc.were analyzed and modeled.Thirdly,Meta-action Unit was mathematical ly defined by the method of Fuzzy Matter-element,with key quality characteristic indexes as similar conditions,the similarity of two Meta-action Units was determined by the distance between them;Actual data were used for analysis and comparsion,which proved the correctness and feasibility of the method,and also provided safeguard for data used in the examples in this paper.(3)The quality characteristic fusion and control mechanism study of Meta-action Unit.Firstly,the inner quality characteristics coupling relationships and fusion mechanisms of Meta-action Unit were researched,and the structure-domain formation mechanism,the process-domain mapping mechanism and the time-domain evolution mechanism of Meta-action Unit quality characteristics were analyzed.Secondly,the quality fluctuation predition model of Meta-action Unit was established,and the quality fluctuation in multistage manufacturing process was predicted comprehensively by the method of Least Squares Support Vector Machine and quality fluctuation transfer function.Thirdly,the correlations among key quality characteristics were analyzed;the degrees of correlations were calculated by the method of Relative Entropy,and then the quality characteristic correlation matrix was obtained,providing evidences for Meta-action Unit quality tracing;Finally,Meta-action Unit quality tracing technology was studied;and the quality tracing flow was analyzed;then the quality tracing system was designed,including function module design and overall structure frame design.(4)The coupling and decoupling technology study of complete machine based on Meta-action Unit.Firstly,the complete machine's complex coupling constrained relationships were decomposed to coupling constrained relationships between each unit;the FMA quality chacarteristic coupling relationship figure and simplified model were obtained based on FMA quality chacarteristic mapping diagram;the coupling effects between unit quality chacarteristics were analyzed;and the same generation matching relationship and different matching relationship of unit quality chacarteristics were researched;then the quality chacarteristic coupling constrained model of complete machine was established.Secondly,the composite coupling strength between unit quality chacarteristics was obtained by calculating the same generation matching coupling strength and different matching coupling strength of unit separately.Based on which,the complete machine quality chacarteristics were decoupling programmed thirdly;the unit quality chacarteristic composite coupling strength was brought into Design Structure Matrix;and the fuzzy DSM based on coupling strength could be obtained after processing;then the method of Multidisplanary Design Optimization was adopted to program the quality chacarteristics to get the optimal control order.(5)The prediction and control technology study of complete machine based on Meta-action Unit.Firstly,based on Meta-action Unit quality prediction and control,the quality control of complete machine could be realized by prediting and controlling unit quality;the method of Adaptive Variable Step Size Back Propagation Network(ABPM)was adopted to predict the upper unit layer's quality satisfaction by entering the lower unit layer quality chacarteristics;and the quality satisfaction ABPM model and flow was established;then MATLAB was used to analyzed and calculate the example to prove the effectiveness of the method.Secondly,the basic principle of quality chacarteristic state space predition and control was analyzed,and the unit quality chacarteristic state space model was established;then the large system multi-layer generalized operator model and quality chacarteristic multi-layer state space model of complete machine based on Meta-action Unit was eatablished by the mode of “Decomposition-Synthesis”.Thirdly,the failure analysis and diagnosis system based on Meta-action Unit was designed and developed,which could monitor and assess the electromechanical product quality chacarteristic state,and also analyzed and diagnose faliures of Meta-action Unit;taing CNC machine tool as an example,the system operating interface was shown to verify the practicalbility of the system. |
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