The digital implementation of control compensators: The coefficient wordlength issue

Abstract

There exist a number of mathematical procedures for designing discrete-time compensators. However, the digital implementation of these designs, with a microprocessor for example, has not received nearly as thorough an investigation. The finite-precision nature of the digital hardware makes it necessary to choose a computational structure that will perform adequately with regard to the initial objectives of the design. This paper describes a procedure for estimating the required fixed-point coefficient wordlength for any given computational structure for the implementation of a singleinput single output LQG design. The results are compared to the actual number of bits necessary to achieve a specified performance index.* This work was performed in part at the MIT Laboratory for Information and Decision Systems with support provided by NASA Ames under grant NGL-22-009-124 and in part at the Charles Stark Draper Laboratory.

Parsimonious System Identification from Fragmented Quantized Measurements

“…However, rigorous analysis did not begin until the 1980's. In [10], [11], considering digital feedback control systems, the authors proposed a way in which one can specify system structures that alleviate the adverse effects of quantization. The works in [12], [13] demonstrate that quantization can induce a chaotic behavior in digital feedback systems.…”