Closed-Loop Identification Applied to a DC Servomechanism: Controller Gains Analysis

Abstract

Usually, when parameter identification is applied, there are some gains related to the identification algorithm whose value must be carefully adjusted in order to obtain a good performance of the algorithm. However, when performing closed loop identification, there are some other constants that in general are not taken into account for the identification algorithm: the controller gains, which may appear inside the identification algorithm, specifically in the regressor vector, which is very important for the parameter convergence according to the persistence of excitation condition. Therefore, the effect of these gains on the estimated parameters should be analyzed so that better estimates can be obtained. This paper addresses the behavior of the parameter estimates for a closed-loop identification methodology applied to a DC servomechanism with a bounded perturbation signal and a PD controller. It is shown that, with this perturbation, the parameter estimates converge to a region whose size can be modified not only by varying the identification algorithm gains but also by modifying the P and D controller gains in a suitable way.

Closed‐loop parameter identification of second‐order non‐linear systems: a distributional approach using delayed reference signals

“…Some significant areas in the field of automatic control where the parameter identification techniques can be applied include model‐based control, fault detection, pre‐compensation, filtering, and state estimation, among others [1]. Besides, a variety of real systems such as robots or servomechanisms are involved in applications requiring high performance, which is usually obtained by a precise knowledge of the system parameters [2–5].…”

“…There are two main approaches for classifying a parameter identification methodology. One approach considers the parameter identification algorithm as an online or off‐line technique [5, 6]. The second approach takes into account the existence of a controller and classifies the parameter identification algorithm as an open‐loop or a closed‐loop methodology [7].…”

“…There are a significant amount of works presenting results on closed‐loop parameter identification of second‐order non‐linear systems. For instance, relay‐based techniques have been applied for parameter identification of DC servomechanisms [5, 16, 17]. Other works dealing with parameter identification of DC servomechanisms using the least‐squares (LS) algorithm or similar approaches can be found in [4, 7, 17–22].…”