A case study on the selection of performance index for design optimization of new controllers

A method of measurement is needed to define quantitatively the performance index for optimum design. Typically, designs are judged subjectively rather than by analytical techniques in which the engineer is trained. To alleviate this problem, the concept of the merit index is introduced to quantize the way in which novel designs are measured. This analytical technique is used as a method in selecting the optimal design. The merit index is a function of the design adequacy, producibility, compatibility, reliability, and cost effectiveness. The design objectives are expressed as probabilities and assigned individual weights to represent the relative importance in the performance index. A design methodology is provided to simplify the design process by utilizing analytical, rather than subjective approaches to optimize product development. The development of a variable-reluctance servo-motor controller is used as a case study to illustrate the technique.<>