Péter Gáspár, Zoltán Szabó, József Bokor

Discrete Feedback Systems 2.

Modern Control

LQG: tracking and regulation

The linear quadratic regulator can generate an offset if either the unmeasured disturbances are non-stationary, i.e. they have slowly drifting behaviour, or there is a mismatch between the plant and the model. As a remedy one can introduce an integral action in the control to deal with plant-model mismatch and reject the drifting unmeasured disturbances. Observe that the regulator solves the problem of moving the system from any initial state to the origin. If it is desired to move the system from any initial condition to an arbitrary set-point, the state feedback control law has to be modified. The problem of regulation in the presence of unknown disturbances, plant-model mismatch and tracking an arbitrary set-point trajectory is solved by modifying the regulatory control law as

, i.e.,

, where

represent the steady state target corresponding to the set-point, say

, and

represents the steady state input necessary to reach this steady state target. This is equivalent to the change of the origin. In this section, we discuss various approaches to incorporate regulation in the presence of drifting disturbances and tracking arbitrary set-point changes.

Tartalomjegyzék

Kiadó: Akadémiai Kiadó

Online megjelenés éve: 2019

ISBN: 978 963 454 373 2

The classical control theory and methods that we have been presented in the first volume are based on a simple input-output description of the plant, expressed as a transfer function, limiting the design to single-input single-output systems and allowing only limited control of the closed-loop behaviour when feedback control is used. Typically, the need to use modern linear control arises when working with models which are complex, multiple input multiple output, or when optimization of performance is a concern. Modern control theory revolves around the so-called state-space description. The state variable representation of dynamic systems is the basis of different and very direct approaches applicable to the analysis and design of a wide range of practical control problems. To complete the design workflow, finally some introduction into system identification theory is given.

Hivatkozás: https://mersz.hu/gaspar-szabo-bokor-discrete-feedback-systems-2//

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