Online fault diagnosis for the hydraulic system which is based on the two-dimensional united fuzzy method is offered,and a dual of fault diagnosis mode combing the wavelet analysis with fuzzy evaluation have been used.The fuzzy array of the fault diagnosis expert system has been structured by using the united weighting allocation method,then an objective and reasonable vector of fault symptoms is obtained by using the theory of evaluation of complex sample variance.In that way,the swiftness and preciseness ...