Research On Reliability Assessment Technology Of Mechatronic Products Based On Meta Action Performance Degradation

Reliability is an important index to measure the performance of complex mechanical and electrical products.Product reliability evaluation runs through all stages of design,development,manufacturing,testing,use and maintenance.Therefore,the research on the reliability assessment methods of complex electromechanical products has important engineering practical significance and value.The traditional reliability assessment is mainly carried out with the failure data of products as the statistical object.The continuous development of modern technology makes the function and structure of electromechanical products more and more complex and intelligent,gradually becoming highly reliable and long-life products,which are often characterized by the difficulty of failure within a specific period of time,or even zero failure.On the other hand,complex electromechanical products(e.g.CNC machine tools)are complex systems with thousands of components,and the use of components to build reliability assessment models will result in underestimation of product reliability,and the direct use of system reliability modeling methods will ignore the internal differences of products resulting in inaccurate product reliability assessment,which bring great challenges to the reliability assessment of complex electromechanical products.In recent years,performance reliability analysis theories and methods based on performance degradation data have gradually provided an accurate and effective means for reliability assessment.With this background and relying on the support of relevant scientific foundation projects,this paper has deeply investigated the theory and method of performance reliability assessment of complex electromechanical products by combining meta-action theory,and the main research contents are as follows.Firstly,the background and significance of the research on the topic of performance reliability analysis and assessment of electromechanical products are systematically discussed.The traditional reliability assessment is introduced,including the general process of assessment methods and the way of source of failure data,etc.Then,the current status of domestic and international research on the reliability assessment of electromechanical products and performance reliability assessment methods and the shortcomings of existing reliability assessment methods for electromechanical products are discussed.Finally,the sources and main contents of this paper and the general framework of the paper are discussed.Then,the basics of meta-action theory,FMA structured decomposition and performance degradation theory are briefly introduced.Then the definition of meta-action performance degradation is given in conjunction with the concept of performance degradation,and the expressions for determining the meta-action performance failure are established with the main performance output parameters of meta-action as the object.The mechanism of meta-action is analyzed with the working principle of meta-action,and the main failure forms of meta-action performance degradation are determined.The performance degradation model is derived and constructed by using Gamma stochastic process to provide theoretical support for the subsequent performance reliability assessment modeling of meta-action units.Finally,the validation process is given as an example with the CNC rotary table of a model of horizontal machining center of domestic THM.Then,based on the relationship between the meta-action unit and the meta-action,the meta-action unit structure is analyzed on the meta-action performance reliability.For the correlation of performance degradation caused by unit structure,Copula theory is introduced,and Copula function is used to portray the correlation of structural parameter degradation among unit parts.To facilitate the analysis,the degradation of unit constituents is assumed to follow the same Gamma stochastic process,and the cumulative distribution function of performance and performance reliability expressions for the meta-action unit are derived using the concept of tandem system.In view of the shortcomings of a single Copula function characterizing the correlation,a hybrid Copula function is constructed in combination with the optimal selection criterion to further improve the prediction accuracy of the model,and its unknown parameters are estimated using an improved NSGA-II optimization algorithm.Finally,the applicability and accuracy of the evaluation model are demonstrated using the gear rotation and rack movement meta-action units of the indexing rotary table of a machining center as an example.Finally,a reliability analysis and evaluation method based on multi-unit performance degradation is proposed for electromechanical products.Firstly,the theory of multi-state system is introduced,and the meta-action unit is regarded as a multi-state system,and a general model for the reliability calculation of the meta-action unit multi-state system is constructed by using the limiting state equation.Then the general generating function theory is introduced to construct the mapping relationship between performance and state,and the state probability is solved by using the discrete method of continuous type random variables.Different interrelation operators are selected to synthesize the mapping relations of multiple units according to the product structure relationship,and the system performance reliability calculation model considering single-unit chain and multiple-unit chain is derived and constructed.Finally,the applicability of this evaluation model is demonstrated with the example of two unit chains under the pallet exchange rack exchange workpiece motion.