A novel fuzzy controller is proposed here to improve the positioning precision of servo system of CNC lathes. To utilize the high-accuracy potential of the VUD fuzzy controller, a grating-ruler was used as a sensor to...
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A novel fuzzy controller is proposed here to improve the positioning precision of servo system of CNC lathes. To utilize the high-accuracy potential of the VUD fuzzy controller, a grating-ruler was used as a sensor to measure the displacement of work pieces. Designing the VUD fuzzy controller involved five steps, i.e., setting up universes of discourse and parameters, selecting membership functions, designing a differential circuit, constructing a base of fuzzy rules, and defining a set of contraction-expansion factors. The method of lookup table was applied to construct the base of fuzzy rules via four typical input instructions, and the method of maximum strength to settle the conflicting rules properly. The experimental results show that the VUD fuzzy controller can be effective in controlling the position of work pieces.
Fuzzy controllers with variable universe of discourse (VUD) have been applied in many fields of intelligent controlling because of their high-accuracy performance. This paper provides a lookup table method to design b...
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Fuzzy controllers with variable universe of discourse (VUD) have been applied in many fields of intelligent controlling because of their high-accuracy performance. This paper provides a lookup table method to design backing-up fuzzy controllers based on VUD. By setting a set of random start points, input-output data pairs are obtained using test-driving method. One data pair defines one fuzzy rule and also assigns the strength of every fuzzy rule. Conflicting fuzzy rule groups are integrated into one fuzzy rule by selecting the one with the maximum strength. A fuzzy rule table is built by the fuzzy rules deduced from input-output data pairs. Simulation experiments show that the VUD fuzzy controller outperforms the general fuzzy controller in accuracy at the final position of the parking lot.
The problem of building an accurate model and the request of real-time control are often simultaneously encountered in the design of control systems. This paper studies and implements a real-time simplified variable d...
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The problem of building an accurate model and the request of real-time control are often simultaneously encountered in the design of control systems. This paper studies and implements a real-time simplified variable domain fuzzy control method in PEM fuel cell flow systems. The method can achieve not only the fine control over cathode pressure of fuel cell stacks by adjusting the input and output domains, but also the real-time control by activating at most four control rules at a time in the inference process for dual-input controller. The experimental results with no load and under a given load demonstrate good performance of this method. The method might also be utilized in other similar processes.
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