Abstract
The assessment for the capabilities of set-point tracking and input disturbance rejection as constituents of performance of PI/PID controllers is presented. Since a single design of controller can not perform optimally to both aspects aforementioned, trade-off between them needs to be considered in the design stage. An index in terms of IAE is defined as the measure for each capability. The overall performance in terms of the two control capabilities will thus be a function of the trade-off made in the design. The relationship between these two indices for optimal trade-off is investigated. For performance assessment, an optimal trajectory of this traded-off design is thus prepared. With this trajectory, a system can be assessed by examining the location of current performance relative to the above optimal trajectory. Furthermore, by reconnoitering the optimal trajectory, some guidelines for better control design are suggested accordingly.
