| Servo motor driving technology is one of the key technologies for controlling CNC machine tools,industrial robots and other important mechanical systems.In the industrial robot system,the servo motor driver must frequently start,run and brake the servo motor control,and the working conditions are variable,so it is easy to appear all kinds of faults,resulting in servo robot action faults,seriously affecting the production efficiency.Analyzing the reliability of the driver has important economic value for making the maintenance plan of the servo system and ensuring the normal operation of the system.In this paper,a degradation model is established to evaluate the reliability of the robot servo drive system through accelerated life test.Firstly,the servo driver is divided into the secondary power supply and the main loop to conduct the principle analysis of the key links,the topology and working principle of the servo driver are studied,the key devices that may degrade and fail are determined,and the parameters representing the degradation of the devices are determined.Then,according to the working environment and test conditions of the servo driver,the equivalent acceleration test scheme of the servo driver is designed from the aspects of loading mode,acceleration stress and equipment selection.The working mode of the servo drive was modified,the test process was designed and improved,and the test data obtained from the measurement were processed.Secondly,the key failure components were determined according to the acceleration test results,and the service life of the servo driver was extrapolated according to the degradation index.Based on the condition that the acceleration stress was the temperature,the activation energy of the key failure components was solved by the Arrennius model,and the acceleration factor was calculated according to the activation energy.The pseudo-life of the servo drive at normal temperature is obtained.According to the test standard of GJB899 A and based on the acceleration test,the confidence intervals of the servo drive MTBF under different confidence degrees were obtained,and the evaluation results were obtained by comparing the obtained results with the evaluation indexes.Then,under the condition of considering individual differences,the degradation model of the servo driver is carried out,and the Arrhenius model is added to the degradation model to complete the acceleration degradation model of the servo driver considering the individual differences.Considering that the degradation model is too complex,the parameter estimation method of MCMC(Markov Monte Carlo Chain)was selected to estimate the parameters of the degradation model.Combined with the test data,the parameter estimation value was obtained through the above methods,and then the evaluation of the servo drive MTBF was obtainedFinally,based on the characteristics of small sample of servo driver,the secondary power supply part of the key link is simulated to realize the sample expansion of servo driver.Saber simulation model is established and verified,and the analysis of working principle of the secondary power supply,determine the key device,according to the component tolerances,saber model of monte carlo simulation of the secondary power,it is concluded that the secondary output power distribution,the degradation data,with the combination of experiment to carry on the information fusion,according to the degradation index,to evaluate servo driver reliability,Then the evaluation of MTBF of servo driver based on sample expansion is realized.This paper is aimed at the characteristics of small sample and high reliability of servo driver,to carry out acceleration test,establish degradation model,to carry out sample expansion and information fusion,to complete the evaluation of servo driver MTBF in a short time. |
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