Multi-Rate Digital Control Systems with Simulation Applications. Volume I. Technical Report

Abstract : The objective of this research effort is to develop a multi-rate/ multiple-order theory for the design of closed-loop digital control systems with characteristics and attributes that are either difficult or impossible to attain with analog or single-rate controllers. The key idea in this methodology is to use the logic of the computer to take a scalar continuous output signal, sample it at a relatively high rate, and then sort out the various sample into a vector of pseudo measurements. The potential of such a scheme is significant, since it offers, among other things, the possibility of using fewer sensors and the potential for providing gracefully degrading system performance in the face of sensor failure. The report is organized in three volumes. Volume I contains the theoretical developments as well as illustrative examples and case studies. The basic tools needed to assess the pseudo measurement concept are reviewed and extended. The concept of the frequency response of the continuous variables of single-rate digitally controlled system is then given sufficient generality to treat multirate systems (including the pseudo measurement concept). A YF-16 case study is used to compare psuedo measurement gains against conventional YF-16 analog controller gains. The pseudo measurement gains are found to be comparable with the conventional gains, indicating the approach does not require control authority more excessive than an analog controller design.