A Concept of a Knowledge-Based Assistance System for Servohydraulic Drive Design

Outsourcing of drive engineering is a tendency to be observed in many industrial enterprises today. As in-house expertise diminishes, competitiveness of hydraulic drive systems compared to electrical drives gains importance. Servohydraulic control systems, however, require very specific and complex approaches to circuit and control design. They are thus demanding on the designer’s knowledge and experience, which often leads to hydraulic solutions being implemented unsatisfactorily or not at all. The concept developed in this paper therefore aims at providing support in drive system design to inexperienced customers or sales people. In order to make the diversity of existing expertise accessible and utilizable, a knowledge-based approach is proposed. The objective is seen in an interactive software tool that guides the user through the iterative process of analyzing the problem, planning and designing the most appropriate drive solution. Requirements and selection criteria for a development environment are specified, and an expert system shell is selected as a means of implementation. A taxonomy of linear hydraulic servo drives is created that provides a frame for an object-oriented knowledge base. Knowledge extracted from text books and expert interviews is integrated into the system as a collection of rules and facts. Special attention is paid to the selection of a control strategy that delivers optimum performance beyond the capability of standard PID controllers. A comprehensive survey of hydraulic control technology is to ascertain that the developed expert system employs both approved and novel techniques to the benefit of overall system performance.