Theoretical Research On The Contamination Control Of Fluid Power System Based On The Fuzzy Stochastic Optimazion

Contaminant is one of the main reasons for the wear, failure and the related downtime of a hydraulic system. As one of the most important ways to abate the contamination level of a hydraulic system, filter plays an important role in controlling the contamination effectively and increasing the reliability of the system significantly. Since there are some uncertain parameters existed in the system, the management of filters has become one of the biggest challenges for the researchers in this field.In this study, an improved mathematical model for the filter management of the hydraulic system with a bypass filter has been introduced to optimize the system operation cost. Based on the above filter management model, an improved interval-fuzzy quadratic programming (IFQP) model and an independent variable controlled interval fuzzy nonlinear programming (IVC-IFNP) model have been established respectively. Considering that the contaminant ingression rates of the hydraulic system can not be determined exactly, a robust interval-based minimax-regret optimization analysis (RIMA) method has been integrated into the above filter management model. Five issues have been indicated from the case studies: (1) Influence of filter allocation strategy on the performance of the hydraulic system can be presented directly in the improved filter allocation model. (2) By introducing the L-R fuzzy numbers, the IVC-IFNP model can improve the quality of the strategy significantly. (3) The RIMA model not only can minimize the regret value of the system operation cost and decrease the randomness of the contaminant ingression rates effectively, but also can play a vital role in helping the decision makers identify the optimal filter allocation strategy from the view of a long-term aspect. (4) The three developed models can perfectly handle the uncertainties existed in the contaminant ingression rates, which can help the decision makers select the filters reasonably. (5) Compared with the INP model, the three developed models can diminish the uncertainties in the system effectively.Based on the three developed models, a decision-support system of the filter management has been developed by utilizing the software package Visual Basic. The system can help the decision makers understand the developed mathematical models and put them into full use. In addition, a testing apparatus has been designed, and examination step and criterion are constituted as well.