ABSTRACT
This chapter considers the effects of the errors on digital filters or compensators and then the effect on the closed-loop digital control system as a whole. The errors may be classified into three types. Type 1 errors are analog-to-digital (A/D) conversion errors where the samples of an analog signal are to be represented by a finite-length binary word. These errors can be handled statistically as random “noise” sequences injected into the control loop. Type 2 errors are multiplication errors where the product of two finite-length binary words must be represented by another word of the same length. This type of error can be treated by the same statistical techniques as type 1 errors. Type 3 errors are referred to as parameter storage errors because control algorithm coefficients must be stored as finite-length words. The effect of these errors can be treated by investigating mathematically the sensitivity of pole locations to changes in coefficient values.
