A Hardware Digital Controller for Undergraduate DDC Experiments

This paper describes a digital control laboratory facility which teaches the central concepts of digital control without requiring a background in digital systems and/or machine language programming. The heart of the laboratory is a flexible hardware digital controller replacing the traditional analog control components in a D. C. servo system. The digital controller can be adjusted to provide versions of the standard PID control algorithm with adjustable word length and computation delay. Through a series of graded experiments this hardware can provide: (1) an introduction to digital control concepts and components, (2) an introduction to digital signal processing, (3) experience with basic DDC algorithms, (4) experience with problems encountered in the choice of sampling rate and digital word length, and (5) experience in working with and trouble-shooting an operating digital control system. Since one controller can be provided for each laboratory station the student has considerable freedom to learn by doing at his own rate.