Research On Load Spectra Compilation Method Of Loaders Based On Hidden Markov Model

Engineering machines,as the important part of equipment manufacturing industry,are always work in a complex and volatile environment.The reliability and durability of their key components will be influenced by various factors,and is also the decisive factor restricting the improvement of quality.Load spectrum is the important inference to realize the service performance test,reasonable top-down design,the indoor load simulation test,life prediction and fatigue analysis of engineering vehicles.How to carry out the statistical analysis of the measured load,select a proper extrapolation method base on multiple factors and optimize the extrapolation method is the key and difficult points in load extrapolate research field.To improve the independent research and development level of domestic loader,this paper based on the project ‘Energy conversation and emission reduction research of engineering machinery'(SQ2015BA0400198)and the Hidden Markov Model theory,take loader as an example,conducted the research on the non-ignorable human factor influences on the load spectrum extrapolation.In the meanwhile,proposed the method to deal with the non-stationary load on account of the cyclic operation.The main research content of this paper is as follows:1.This paper takes loaders as object of the research,elaborates the load measure method of loader load spectrum.Including various aspects such as the basic condition of the experimental prototype,the test site,material preparation,the formulation of test plan,the determination of the sample size,collection point and the installation of the sensor.Then take the loader lift cylinder pressure data as example,preprocessed the measured load data,eliminated the trend item,realized digital filter and spike detection.This paper can provide some experience for the test and research of loaders.2.In view of the problem that the frequent manual operation of engineering vehicles,and the fact that load properties can be greatly influenced by operating mode.This paper considered several factors and then divided driver's operation style into three types,that is,ordinary type,rude type and gentle type.Hidden Markov Model has achieved good performance in mode recognition and fault diagnosis field,therefore it can be used in there to recognize the driver's operating type.First to train the load data by Baum-Welch algorithm,then match log likelihood ration with each model to recognize the type.Consider the data property of three operating types,this paper select the extrapolation method respectively as rainflow matrix extrapolation method,POT extrapolation method,parameter estimation extrapolation method.By taking human factor into consideration,the proper selection of extrapolation method can be realized.3.In view of the condition that measured load is non-stationary caused by the complex working condition and cyclic operation.This paper conducted section method to translate the load into several stationary sections,and use round test to check out the stationarity of each section.This paper processed the transition load by Hidden Markov method.It can take the transition data,which will be neglected by section method,into consideration.Then the overall rainflow matrix produced by section method are compared with the expected rainflow matrix produced by Hidden Markov method,the practicable of the method can be verified.Through this method,more valuable information can be contained in the load extrapolation process.The accuracy of extrapolation can be improved.Finally,use the GUI function in MATLAB,developed software called “A Software to Processing Non-stationary Load of Engineering Vehicles V1.0”.The software includes load process part and load reconstruction part.This software can provide convenience for research workers,and normalize the load procession.This paper,in view of the feature of loader,researched on the selection and improvement of load extrapolation method based on Hidden Markov theory,achieved the recognition of driver's driving type and proposed the non-stationary load processing method.This paper makes a contribution to improve the accuracy of extrapolation,and provide basis to the reliability design of engineering vehicles.