The Research Of Reliability Optimal Allocation Methods Of Mechanical Arm Based On Effort Functions

As an important part of industrial automation production,the reliability level of industrial robot directly determines the efficiency of automation.At this stage,the comprehensive quality and reliability of domestic industrial robots still have a large gap with the industrial robots in industrialized countries,and the domestic industrial robot market has also been occupied by foreign brands for a long time.Therefore,how to improve the reliability and quality of domestic industrial robots and enhance the competitiveness of domestic independent brands has become one of the key issues faced by industrial robot manufacturing enterprises and research team in China.As the actuator of industrial robot,the reliability of mechanical arm relates to the performance and reliability of the whole robot system.Therefore,it is of great importance to analyze the reliability of robotic arm.In this paper,FMECA technology was used to systematically analyze the failures of mechanical arm,which determined the failure information,such as failure modes and failure effect.On the basis of failure analysis,the weak components in the system were found out through the criticality analysis,and the corresponding improvement measures were put forward.Based on the Markov process,the reliability model of the system was established and the various reliability indexes of the system were determined.Considering the inaccuracy of the failure rate and repair time,fuzzy set theory was introduced to deal with them.Combined with the α-cut and fuzzy number arithmetic rule,the determination value,fuzzy value and membership function of each reliability index of lumbar mechanism subsystem were calculated,which provided a more comprehensive reliability analysis.The reliability effort function of mechanical arm was established considering the failure and reliability analysis.At the same time,influence factors:the severity of the failure modes,potential for reliability improvement,criticality importance and maintenance were considered to determine effort coefficient of each component by using the entropy weight method,which further improved the effort function model.In order to maximize the system reliability and keep improvement effort as less as possible,a method to optimize the reliability of mechanical arm was proposed.The multi-objective optimization algorithms NSGA-Ⅱ and SPEA2 were used to solve the optimization model.The optimization results of the two algorithms were basically coincident,which proved the accuracy of the optimization results and obtained the optimal allocation of reliability of mechanical arm.The method respected the objective reliability analysis of the mechanical arm,reduced the influence of the subjective factors in the process of reliability allocation,and overcome the disadvantages of the over-allocation of the traditional method.