Research Of Key Problem On I-DEAS-based Intelligent CAD System For Hydraulic Systems Used In Machine Tools

Since twenty century 90 years, with the rapid development of computer and artificial intelligence technology, Intelligent CAD technology in the design of hydraulic system has been the one of the study hotspot on computer application. The intelligent CAD system for hydraulic systems used in machine tools is a re-development of CAD systems based on SGI workstation and I-DEAS software. Intelligent design of the hydraulic system can be done by means of establishing a knowledge bank and a diagram bank with a reasoning mechanism of the expert system.It is mainly composed of the following:1. Establishment of a knowledge bank and a diagram bank of the hydraulic system. Component symbol graph and diagrams of commonly-used circuits are stored in the diagram bank. The former is a basic module based on Chinese national standard GB/T 786.1—93: Hydraulic and Pneumatic Diagram Symbols. The latter contains dozens of typical hydraulic circuits such as pressure regulating circuits, speed-regulating circuits, circuits of multi-cylinder motion and other circuits etc. The user may produce the hydraulic system he needs by making a few partial changes by reference to the typical circuits.The knowledge bank consists of hydraulic component bank. It contains the knowledge of facts. The impersonally entity and relation is described by means of planar table method. Establishment of a knowledge bank's relation model, the required result can be obtained by reasoning with a mechanism of depth-priority search.2 Reasoning mechanismThe reasoning mechanism is a mechanism for controlling and coordinating the operation of the whole expert system. The systematic solution to present problems can be obtained by using and calling the facts and rules in the knowledge bank according to certain reasoning strategy. The hydraulic components are selected by ceaselessly producing and transforming the rules expressed by rules objective and the data expressed by the facts objective with the integrated mechanism of prolog language itself and recall function through match recur by using the search strategy of depth priority.3. Calculation module of static data design and computation checking module of system performance.This system adopts the dialogue block. As long as the user enters the required technical data, the computer will calculate the pressure, flow rate, strength, power and power match of the system to be designed so as to determine the technical data of various components in the system. The calculation result will be stored in file form according to a certain format for future use. The checking module of system performance can be used by the user to check the performance of the whole system such as pressure loss, system...