ABSTRACT

Large plant uncertainty reduces the available feedback. On the basis of the information used for the adaptation, the adaptive controllers can be divided into three types. The first type uses sensor readings of environmental parameters and plant parameter dependencies on these environmental factors to correct the control law. A brief description is provided for adaptive systems for flexible plants, for disturbance rejection and noise reduction, and for dithering systems. Plant parameter uncertainty impairs the available feedback. Disturbance sources and plant parameter uncertainty both contribute to the feedback- system output error. During the system analysis, the main feedback loop dynamics can be assumed to be independent of the process of adaptation, and the prefilter and the main loop links can be considered time invariant. Plant identification is ill-conditioned over the bandwidth of large feedback where the error frequency components are small, and therefore, the pilot signals must be very small.