Reparto frecuencial de la realimentación en estructuras en cascadaaplicación al control robusto de un servomotor

Abstract

One of the main advantages of cascaded control architectures is to provide the control system with a faster temporal response to disturbances in the inner loop, which can lead to excessive control bandwidth. The control architecture and design methodology presented in this paper focuses on using the amount of feedback that is strictly necessary at each frequency to ensure the specified reference tracking and disturbance rejection. The next critical issue is how to distribute this feedback between the inner and outer loops. The present work solves a specific problem, the position control of a servomotor where its speed is also accessible, and illustrates how the switching frequency between loops significantly affects the amplification of the measurement noise, anticipating a possible saturation of the actuator. The control architecture uses two feedback controllers and one feedforward controller. The designs are based on Quantitative Feedback Theory (QFT) and are therefore robust. The working environment allows the incorporation of any type of control specification, facilitates the iterative design of both loops, and makes it possible to balance the complexity of the controllers and their bandwidth.