MTEEP: mechanical transmission element expert system

ABSTRACT

MTEEP (Mechanical Transmission Element Expert) is an expert system for the design of mechanical transmission elements and proper material selection. Much of the research and development in Engineering with respect to expert systems has been confined to Electrical Engineering. Less research has taken place towards the development of an efficient expert system in the field of Mechanical Engineering Design. Many of the problems encountered by mechanical designers are complex and time consuming. A designer is usually presented with design jobs that have different desired functions, constraints, and trade-offs. There is always the need for greater accuracy and more reliability of the designed component. Most designers today try to solve design problems using their experience and engineering judgement. To achieve greater accuracy and reliability, the designer has to make use of the right tools, rare expertise and other expensive mechanisms which few can afford. Mechanical Engineering Design is partly subjective. Equations and accepted derivations form the main body of knowledge concerning design. These provide the minimum and the maximum configurable values. These values are subject to change if the designer so feels. The theoretical design values should only be substituted with values that have been generated by experts in this field. MTEEP, the design expert system, has been designed to enable designers to choose between theoretical mathematically derived and experience-based practical values for a particular range of application areas. A major objective of MTEEP is to give all designers a uniform methodology. In today's world most of the design work is done on a team basis. Some members do the element design, some concentrate on proper material selection, while others are involved in finding the most economical manufacturing process within the constraints of available machines. Such a design process is an inefficient utilization of manpower, creativity, intelligence and capital. All of this work can be done by one system, the MTEEP. There is always a chance that a team's work will be inconsistent and nonuniform, but this would never be true with MTEEP. All the expertise of the members of a design team can be represented in the knowledge base of the MTEEP. A major obstacle in building a reliable expert system is getting the right knowledge from the domain expert and coding and structuring it in the proper form into the knowledge base of the system. The knowledge engineer must take care to modularize the knowledge base of the system so as to make it practical and fast for use in mechanical design. Modularization of the knowledge base would result in efficient access of the knowledge base. Maintenance and updates would also be much easier. An important characteristic of MTEEP which differentiates it from many other expert systems is that it has access to two knowledge bases at the same time. The two knowledge bases are, the experienced-based knowledge base and the theory-based knowledge base. The first is dynamic in nature while the second is static. The combination of these two makes MTEEP a designer and a consultant at the same time. The presence of a dynamic experience-based knowledge base with a theoretical rule based knowledge base makes MTEEP an expert system with a complex, possibly unique, basic design. The purpose of the experience-based knowledge base is to try to capture expertise, ideas and experience of the experts in this field. The experience-based knowledge base provides a way of automating consistent reasoning with practical experience in mechanical engineering design. When an expert works with this expert system he can, if he so desires, pass on his own experience and knowledge to the system which can be stored in the experience-based knowledge base on a permanent basis. He can also make a mention of any deviation he sees in the practical world from values of elements calculated by the MTEEP. All this knowledge and facts are later made available for tutorial use, or to help a novice designer. This combination of knowledge bases is very helpful and successful not only when designing elements with unconventional parameters but also in helping a designer to double check his design (that is, substantiating theoretical design with accepted practical values). This would lead to a substantial decrease in the possibility of an error on the part of the human designer. The MTEEP system would become more efficient and more reliable with use. MTEEP is an expert system where each expert of this field has the freedom to become his own knowledge engineer/ domain expert. It is difficult to build a good and efficient expert system in a short period of time. A major hurdle is the time it takes to get the right knowledge from the domain expert. This major constraint is easily overcome in this system. The knowledge base dependent on the domain expert is not completely built before the system is operational, but is built with the passage of time, as the system is used by reliable human experts. It is well known that in a rule based system, rules are generally tied to different conditions in a Boolean formula. When Boolean operators string these conditions together, each may be referred to in more than one rule. Problems arise when a condition is no longer applicable or when a new rule has been added. At that point, instead of expected expertise, the system can deliver nonsense. This problem is detected by the experience-based portion of the MTEEP system. As is the case with most expert systems, MTEEP also makes use of heuristic rules of thumb or simplification that limit the search for an efficient solution.

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.2 ARTIFICIAL INTELLIGENCE
      I.2.1 Applications and Expert Systems
          Subjects: Industrial automation

Additional Classification:
  J. Computer Applications
  J.2 PHYSICAL SCIENCES AND ENGINEERING
      Subjects: Engineering

General Terms:
Design, Performance, Theory