SELF-DIAGNOSIS OF HYDRAULICCIRCUITS USING EXPERT SYSTEMS

The rapid advances in computer, microcomputer and microprocessor technology has opened many new application possibilities for the fluid power industry. Smart controllers integral to the hydraulic component are now commercially available using concepts which as much as five years ago were considered strictly academic.Associated with this growth has been the development of computer software for purposes of control, data collection and manipulation, circuit simulation and design. The combination of the microcomputer with relevant software can produce a very powerful design and control tool specifically oriented towards fluid power applications. One such approach uses a microcomputer and the reasoning capabilities of an artificial intelligence based high-level language programming technique known as “expert systems”.An expert system allows the programmer to develop both mathematical and symbolic logic in terms of defined words and phrases called rules. These rules can tell the computer to monitor a certain device, to switch on or off a specified valve, or to do a complex mathe matical evaluation if acertain set of conditions are satisfied. Use, then, of an expert system in controland condition monitoring is greatly facilitated using this approach. If theserules are coded to relfect verbalstatements rather than analyticin for mation, then the expert system can beapplied as an example to the process of design.This paper will consider the application of an expert system to the control, monitoring, and self-diagnosis ofa hydraulic circuit. The philosophy behind the expert system approach will be briefly examined and its application to diagnosis and control of a hydraulic circuit presented through very basic examples.