FREQUENCY-DOMAIN DESIGN METHODOLOGY FOR UNCERTAIN CASCADED MULTIPLE-LOOP SYSTEMS WITH PLANT MODIFICATION

Since the internal signal level increases after using a plant modifica tion loop, Horowitz and Wang (1979, 1988) proposed a quantitative synt hesis feedback design method using the bandwidth propagation effect to take care of the internal signal level. The bandwidth increase phenom enon makes it hard work to maintain internal signal level reasonably. Moreover, the noise components are most important in the high-frequenc y range. It is desirable to decrease loop transmission functions as fa st as possible in the high-frequency range to achieve minimum sensor n oise sources. In the paper, a frequency domain design methodology for uncertain cascaded multiple-loop systems with plant modification is de veloped. The plant uncertainties are transferred to the values of equi valent external disturbances at the plant output. Thus, the design pro blem will become an equivalent external disturbance rejection problem. At the same time the bandwidth propagation effect can be eliminated a nd loop transmission functions decrease as quickly as possible.