An Integration method over a moving window for exponential convergence in adaptive control without persistency of excitation

Date

2016

Author

Yayla, Metehan

Metadata

Show full item record

Item Usage Stats

253
views

0
downloads

Adaptive control has great capabilities in control of uncertain systems to maintain a consistent and desired performance. Another control methodology concerning the uncertain systems is the robust control. It is well-known that the robust control has advantages of dealing with external disturbances, unmodeled dynamics, and quickly varying uncertain parameters. Nonetheless, robustness against these environmental, and parametric uncertainties degrades the tracking performance. Besides, adaptive control can tolerate parameterizable uncertainties to guarantee the closed-loop stability. Hence, the solution becomes the adaptive augmentation of robust baseline controller, Model Reference Adaptive Control (MRAC). Baseline MRAC ensures asymptotic tracking performance using instantaneous data, but parameter convergence is achieved if and only if the system signals are persistently exciting (PE). Furthermore, without PE, even boundedness of the signals are not guaranteed in the presence of bounded disturbances. To address this, many robust modifications are introduced in the literature. However, parameter convergence remained as an open question. Recently introduced Concurrent Learning Model Reference Adaptive Control (CL-MRAC) solved this issue using recorded data concurrently with the current data assuming the state derivatives are available. In this thesis, a new integration method for exponential stability without PE is introduced. Proposed method uses the time histories of the system signals and control inputs for the online identification of uncertainties. Once these identified parameters are available, weight update law in conjunction with σ-modification is updated. Eventually, global exponential stability is established. The algorithm does not require PE, and state derivatives are not used in the identification.

Subject Keywords

Adaptive control systems., Automatic control., Robust control.

URI

http://etd.lib.metu.edu.tr/upload/12620301/index.pdf
https://hdl.handle.net/11511/25955

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

A Control System Architecture for Control of Non-Affine in Control, Open-Loop Unstable Underactuated Systems Marangoz, Alp; Kutay, Ali Türker (2017-07-25) In this paper, a control system architecture for control of non-affine in control, open-loop unstable underactuated system is discussed. Passivization of the unactuated (internal) system dynamics achieved through perturbation of trajectories of the actuated states, which are calculated through adaptive dynamic inversion technique, based on Tikhonov's theorem. Performance of the controller is shown through simulation of two open-loop unstable and locally uncontrollable example problems.
A strategy to enhance AGC performance of power systems that suffer inter-area oscillations and a case study for Turkish power system Tanidir, O.; Cebeci, M. E.; Gencoglu, C.; Tor, O. B. (2012-12-01) Sufficient fast secondary reserve and its adequate dynamic activation are the key factors in satisfying automatic generation control (AGC) performance of a power system. Dynamic activation of the secondary reserves should also not introduce any negative damping to inter-area oscillations. This study presents a strategy to enhance AGC performance of a power system considering these concerns. Objective function is minimizing the amount of fast secondary reserves to mitigate ancillary service cost. The constra...
A New Model Predictive Torque Control Strategy with Reduced Set of Prediction Vectors Şahin, İlker; Keysan, Ozan (2018-04-12) Major drawback of finite control set model predictive control (FCS-MPC) is its high computational burden. This paper proposes a new optimal vector selection strategy that reduces the computational cost of FCS-MPC technique. Considering two-level voltage source inverters (2L-VSI) utilized as motor drives, proposed strategy reduces the number of active prediction vectors from six to three. Hence, cost function is evaluated only for four vectors (three active and one zero). Moreover, between the two possible z...
A Model Based Approach for Sensor Fault Detection in Civil Aircraft Control Surface Sercekman, O.; Kutay, Ali Türker (2018-04-26) A model-based fault detection and diagnosis (FDD) solution improves the capability in a civil aircraft control surface whereas having low complexity and computational requirements. The main objective of the FDD. techniques that are extensively applied in industrial systems is to increase the sensitivity of fault detection scheme while maintaining a reliable system response with respect to additional unknown inputs. In the paper, a reformative approach to an observer-based fault detection method is introduce...
A multitone model of complex enveloped signals and its application in feedforward circuit analysis Coskun, AH; Mutlu, Ayşe Ceyda; Demir, S (Institute of Electrical and Electronics Engineers (IEEE), 2005-06-01) Analytical tools that characterize nonlinear systems are essential and need to be developed for initial rapid optimizations and understanding of the system performance. Modeling of the input signal is a crucial part of this task. In this paper, a multitone representation for an arbitrary double-side banded (symmetric spectrum around carrier frequency) stochastically not well-defined signal and its application to a feedforward circuit, which involve two nonlinear amplifiers, couplers, phase, and delay units ...

Citation Formats

M. Yayla, “An Integration method over a moving window for exponential convergence in adaptive control without persistency of excitation,” M.S. - Master of Science, Middle East Technical University, 2016.