| Prognostics and Health Management(PHM)technology is a new type of maintenance and management.It can not only identify the fault pattern of equipment,predict the status,reliability,and remaining life of equipment by processing the information about status monitoring,but also scientifically and rationally plan and manage equipment maintenance activities by considering the equipment maintenance,usage as well as work environment information and combining with standardized equipment management methods and processes.Some key technologies such as performance degradation and health prediction,health decay evolution rules,the optimal maintenance of dynamic programming and so on in PHM were studied in the paper.Using sea-based equipment as a target,a health prediction model based on an improved degenerate Hidden Markov Model was established.A comprehensive regression evolution rule for coordinating internal maintenance effectiveness factors and external environmental condition factors was studied.On this basis,a multi-objective optimal preventive maintenance strategy was studied and established.The main research contents of the paper are as follows:(1)Fault pattern recognition method of equipment based on HMM was studied.By using this model,it can transform the slow changing signal characteristics into large logarithmic likelihoods and realize the effective recognition of fault pattern.Based on this,the state prediction model of equipment based on HMM-GA-SVR was further proposed to realize the prediction of equipment working status.Through the simulation of the ship power equipment diesel engine,the results showed that the above model had a high recognition rate and can accurately predict the current state of the ship power equipment.(2)Based on the characteristics of sea-based equipment,the decline evolutionary rules of equipment for the introduction of adjustment factors and environmental factors were studied.Based on the assumption that the equipment life is subject to the Weibull distribution,taking the deck mechanical equipment as an example,in addition to considering its own internal decay rules,parameters such as salt spray,vibration,corrosion,and temperature were estimated.The model which considering the influence of environmental factors on equipment degradation evolution rule was established and performed a simulation of the example.(3)Multi-objective optimal preventive maintenance strategy was studied.Under the decline evolution rules of equipment that considering environmental factors,a decision model with the goal of maximum availability of steady-state and minimum average cost rate was established,so that optimal preventive maintenance intervals could be solved.In order to verify the influence of the external environment on the quality of equipment work,the preventive maintenance interval under different environmental conditions was analyzed.The simulation results of the example showed that the harsh environment would accelerate the decline of the equipment,drastically shorten the time interval for preventive maintenance.It complied with the rules of equipment degradation in the actual process,which verified the effectiveness of the decision model. |
