Abstract: A feedback control system modifies a drive signal to a plant which provides an achieved response signal in response to the drive signal. A first summing element provides a response error signal representing the difference between a desired response signal and the achieved response signal. An adaptive filter adjusts the response error signal in accordance with a dynamic behavior of the adaptive filter to provide a drive correction signal, the dynamic behavior being adjusted by a compensation device in response to the drive signal and the achieved response signal. A second summing element provides a corrected drive signal representing the sum of the drive signal and the drive correction signal. A storage device delays the corrected drive signal and a converter generates the drive signal during the next iteration as a function of the delayed corrected drive signal.

Abstract: A feedback control system provides an adjusted command signal to a plant in response to a command signal having a plurality of command signal components. The plant controls a subsystem and provides a feedback signal representative of the subsystem's achieved response to the adjusted command signal. An adaptive filter adjusts the amplitude and phase of relatively high frequency command signal components in accordance with a dynamic behavior of the adaptive filter. A compensation device adjusts a dynamic behavior of the adaptive filter in response to the feedback signal and the adjusted command signal. In one form of the invention, a low-pass filter passes command signal components of relatively low frequency, and a summing element generates the adjusted command signal in response to the output from the adaptive filter and the command signal components passed by the low-pass filter.

Abstract: In a feedback control system, a reference input element adjusts the amplitude and phase of a sinusoidal component of a command signal applied to the control system to cancel the transfer effects of the feedback loop, substantially eliminating error between a feedback signal and the common signal. The reference input element processes the sinusoidal component of a command signal through a network metaphor of a trigonometric identity. Adjustment of weights of the trigonometric identity permits arbitrary adjustment of the amplitude and phase of the command signal. A comparison of the command signal and the feedback signal, or of analogous signals, is used as an input to an automated trigonometric identity weight adjustment routine in the reference input element.

Abstract: Parallel multistage, multirate digital filters are executed by a digital signal processor for signals on a plurality of channels. Parallel signals are converted from a first sampling frequency to a second sampling frequency by applying the signal from each channel to one of the substantially identical multistage, multirate digital filters. Each stage of each multistage, multirate digital filter includes a plurality of subfilters and a commutator for indicating a subfilter for execution. The commutators index at the same frequency for like stages of each multistage, multirate digital filters. Initial commutator positions are staggered between multistage, multirate digital filters at at least the highest rate stage. Variable delay lines may be included in each channel to compensate for interchannel data skew introduced by commutator staggering.