Report on Contract F05611-76-90203. Volume I

The main goal of this project was to explore ways in which digital filters could be used for isopad seismic vibration control. This goal was formulated after many analog circuits were built and tested to give the appropriate amount of phase lead in the proper frequency bands. None of the analog circuits had been totally successful in giving the required amount of lead. Unfortunately, in the literature of digital filters, there is very little, if any, useful information concerning the phase characteristics of digital filters. The primary goal was to explore the phase characteristics of digital filters relative to the isopad control problem. The end goal of the isopad control problem is to execute various control loops, presumably one for each degree of freedom of the isopad, to control the isopad in real time using digital filters, either exclusively, or in conjunction with analog filters. It was originally conceived that the project would be carried out by developing software on the PDP11/45 and then down-line loading the program into the PDP11/03 computer which is based on the LSI-11 microprocessor. Thus, using microprocessor technology, it would be cost effective to use a controller per axis concept and the interaction or cross-coupling in the processors would be extremely well-defined by passing only the required parameters when needed between processors. This approach proved to be not feasible to put into practice because of the processing requirements of the filters. See also Volume 2, AD-A085 437.