scholarly journals Adaptive control of time-invariant systems with discrete delays subject to multiestimation

2006 ◽  
Vol 2006 ◽  
pp. 1-27 ◽  
Author(s):  
M. De la Sen ◽  
S. Alonso
Keyword(s):  
Closed Loop ◽  
Dead Zone ◽  
Adaptive Controller ◽  
Pole Placement ◽  
Adaptation Mechanism ◽  
Discrete Delays ◽  
Estimation Scheme ◽  
Bounded Disturbances ◽  
True Basic ◽  
Minimum Residence Time

This paper deals with a robustly stable adaptive pole-placement-based controller for time-delay linear systems with unknown point delays within known intervals of sufficiently small lengths under unmodeled dynamics and bounded disturbances. A multiestimation scheme is used to improve the identification error and then to deal with possible errors between the true basic delays compared to that used in the regressor of the adaptive scheme. Each estimation scheme possess a relative dead zone for each estimation scheme which freezes the adaptation for small sizes of the adaptation error compared with the estimated size of the contribution of the uncertainties to the filtered output. All the estimation schemes run in parallel but only that, which is currently in operation, parameterizes the adaptive controller to generate the plant input at each time. A supervisory scheme chooses in real time the appropriate estimator subject to a minimum residence time which is the tool to ensure closed-loop stability under switching between the estimators in the estimation scheme. The dead zone adaptation mechanism prevents the closed-loop system against potential instability caused by uncertainties.

scholarly journals Robustly stable multiestimation scheme for adaptive control and identification with model reduction issues

2005 ◽  
Vol 2005 (1) ◽  
pp. 31-67 ◽  
Author(s):  
A. Bilbao-Guillerna ◽  
M. De La Sen ◽  
A. Ibeas ◽  
S. Alonso-Quesada
Keyword(s):  
Adaptive Control ◽  
Closed Loop ◽  
Dead Zone ◽  
Adaptive Controller ◽  
Pole Placement ◽  
Switching Rule ◽  
Estimation Scheme ◽  
On Line ◽  
Minimum Residence Time ◽  
And Control

A discrete pole-placement-based and multiestimation-based adaptive control scheme involving a relative adaptation dead zone is presented for a plant with known poles and unknown zeros. The basic usefulness of the proposed multiestimation scheme is related to the use of a set of models of reduced order associated with the multiestimation scheme instead of a high-order one. Depending on the frequency spectrum characteristics of the input and on the estimates evolution, the multiestimation scheme selects on-line the most appropriate model and its related estimation scheme in order to improve the identification and control performances. Robust closed-loop stability is proved even in the presence of unmodeled dynamics of sufficiently small sizes as it has been confirmed by simulation results. The scheme chooses in real time the estimator/controller associated with a particular reduced model possessing the best performance according to an identification performance index by implementing a switching rule between estimators. The switching rule is subject to a minimum residence time at each identifier/adaptive controller parameterization for closed-loop stabilization purposes. A conceptually simple higher-level supervisor, based on heuristic updating rules which estimate on-line the weights of the switching rule between estimation schemes, is discussed.

scholarly journals PASSIVITY BASED FRACTIONAL ORDER ADAPTIVE CONTROL OF DEPTH OF ANESTHESIA

2019 ◽  
Vol 49 (3) ◽  
pp. 155-161
Author(s):  
M. BOROOJERDI ALAVI ◽  
M. TABATABAEI
Keyword(s):  
Fractional Order ◽  
Adaptive Controller ◽  
Pole Placement ◽  
Model Parameters ◽  
Depth Of Anesthesia ◽  
Model Uncertainties ◽  
Adaptation Mechanism ◽  
Polynomial Coefficients ◽  
Simulation Results ◽  
Model Reference Adaptive

In this paper, a passivity based model reference adaptive controller with fractional-order adaptation mechanism is utilized for control of depth of anesthesia. The propofol infusion rate is adjusted to reach an appropriate Bispectral Index (BIS). The Pharmacokinetic-Pharmacodynamic (PK-PD) model is employed to model the distribution of propofol in patient body. Since, the PK-PD model parameters depend on physical specifications of patient, employing an adaptive controller to control this system is inevi-table. The utilized controller is a pole placement con-troller in which its polynomial coefficients are ad-justed according to a fractional-order adaptation mechanism. Simulation results on several patients demonstrate the efficiency of the proposed method in the presence of disturbance, noise, and model uncertainties.

scholarly journals Stability and assignment of spectrum in systems with discrete time lags

2006 ◽  
Vol 2006 ◽  
pp. 1-8 ◽  
Author(s):  
M. De la Sen
Keyword(s):  
Asymptotic Stability ◽  
Closed Loop ◽  
Pole Placement ◽  
Time Lags ◽  
Matrix Inequalities ◽  
Delayed Systems ◽  
Spectrum Assignment ◽  
Discrete Delays ◽  
Identical Number ◽  
Point Delays

The asymptotic stability with a prescribed degree of time delayed systems subject to multiple bounded discrete delays has received important attention in the last years. It is basically proved that theα-stability locally in the delays (i.e., all the eigenvalues have prefixed strictly negative real parts located inRe⁡s≤−α<0) may be tested for a set of admissible delays including possible zero delays either through a set of Lyapunov's matrix inequalities or, equivalently, by checking that an identical number of matrices related to the delayed dynamics are all stability matrices. The result may be easily extended to check theε-asymptotic stability independent of the delays, that is, for all the delays having any values, the eigenvalues are stable and located inRe⁡s≤ε→0−. The above referred number of stable matrices to be tested is2rfor a set of distinctrpoint delays and includes all possible cases of alternate signs for summations for all the matrices of delayed dynamics. The manuscript is completed with a study for prescribed closed-loop spectrum assignment (or “pole placement”) under output feedback.

Robust Adaptive Control for Hydraulic Servosystems

1996 ◽  
Vol 118 (2) ◽  
pp. 237-244 ◽  
Author(s):  
A. R. Plummer ◽  
N. D. Vaughan
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Controller Design ◽  
Adaptive Controller ◽  
Robust Adaptive Control ◽  
Recursive Least Squares ◽  
Pole Placement ◽  
Line System ◽  
Self Tuning ◽  
Robust Adaptive

The application of an indirect (self-tuning) adaptive controller to an electro-hydraulic positioning system is described. The underlying control method is pole placement, with the addition of a demand filter to allow noise effects to be reduced without degrading closed-loop performance. Recursive least squares is used to estimate the plant parameters, but the data is pre-filtered to reduce bias. A novel covariance trace limiting algorithm provides estimator reliability despite periods of insufficient excitation. Off-line system identification is employed to help controller design for the electro-hydraulic servosystem. The resulting controller performs well, and adapts rapidly to changes in load stiffness and supply pressure.

A Note on Pole Placement of Mechanical Systems

1991 ◽  
Vol 113 (3) ◽  
pp. 420-421 ◽  
Author(s):  
C. Minas ◽  
D. J. Inman
Keyword(s):  
Least Squares ◽  
Canonical Form ◽  
Output Feedback ◽  
Closed Loop ◽  
Weighted Least Squares ◽  
Mechanical Systems ◽  
Pole Placement ◽  
Feedback Gain ◽  
Closed Loop System ◽  
Feedback Method

An output feedback method is developed, that systematically places a desired number of poles of a closed-loop system at or near desired locations. The system is transformed to its equivalent controllable canonical form, where the output feedback gain matrix is calculated in a weighted least squares scheme, that minimizes the change of the remaining modes of the system. The advantage of this method over other pole placement routines is the fact that the influence on the remaining unplaced modes of the system is minimum, which is particularly important in preserving closed-loop stability.

Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuator System Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuato

2021 ◽  
Vol 20 (2) ◽  
pp. 25-32
Author(s):  
Noorhazirah Sunar ◽  
Mohd Fua’ad Rahmat ◽  
Ahmad ‘Athif Mohd Fauzi ◽  
Zool Hilmi Ismail ◽  
Siti Marhanis Osman ◽  
...  
Keyword(s):  
Dead Zone ◽  
Pneumatic Actuator ◽  
Pole Placement ◽  
Position Tracking ◽  
Zone Model ◽  
Feed Forward ◽  
The Dead ◽  
Chattering Effect ◽  
Pole Placement Controller ◽  
Pole Placement Control

Dead-zone in the valve degraded the performances of the Electro-Pneumatic Actuator (EPA) system.  It makes the system difficult to control, become unstable and leads to chattering effect nearest desired position.  In order to cater this issue, the EPA system transfer function and the dead-zone model is identified by MATLAB SI toolbox and the Particle Swarm Optimization (PSO) algorithm respectively.  Then a parametric control is designed based on pole-placement approach and combine with feed-forward inverse dead-zone compensation.  To reduce chattering effect, a smooth parameter is added to the controller output.  The advantages of using these techniques are the chattering effect and the dead-zone of the EPA system is reduced.  Moreover, the feed-forward system improves the transient performance.  The results are compared with the pole-placement control (1) without compensator and (2) with conventional dead-zone compensator.  Based on the experimental results, the proposed controller reduced the chattering effect due to the controller output of conventional dead-zone compensation, 90% of the pole-placement controller steady-state error and 30% and 40% of the pole-placement controller with conventional dead-zone compensation settling time and rise time.

Backstepping Based Adaptive Control of Magnetic Levitation System

2013 ◽  
Vol 341-342 ◽  
pp. 945-948 ◽  
Author(s):  
Wei Zhou ◽  
Bao Bin Liu
Keyword(s):  
Parameter Uncertainty ◽  
Closed Loop ◽  
Controller Design ◽  
Magnetic Levitation ◽  
Adaptive Controller ◽  
Closed Loop System ◽  
Actual System ◽  
Levitation System ◽  
Magnetic Levitation System ◽  
Control Accuracy

In view of parameter uncertainty in the magnetic levitation system, the adaptive controller design problem is investigated for the system. Nonlinear adaptive controller based on backstepping is proposed for the design of the actual system with parameter uncertainty. The controller can estimate the uncertainty parameter online so as to improve control accuracy. Theoretical analysis shows that the closed-loop system is stable regardless of parameter uncertainty. Simulation results demonstrate the effectiveness of the presented method.

scholarly journals On the Robust Multiple Objective Control with Simultaneous Pole Placement in LMI Regions

2021 ◽  
Vol 20 ◽  
pp. 272-280
Author(s):  
Antonis Vouzikas ◽  
Alexandros Gazis
Keyword(s):  
Robust Control ◽  
Complex Plane ◽  
Uncertain Systems ◽  
Closed Loop ◽  
Pole Placement ◽  
Multiple Objective ◽  
Control Laws ◽  
Control Approach ◽  
Guaranteed Cost ◽  
Objective Control

This article studies the problem of designing robust control laws to achieve multiple performance objectives for linear uncertain systems. Specifically, in this study we have selected one of the control objectives to be a closed-loop pole placement in specific regions of the left-half complex plane. As such, a guaranteed cost based multi-objective control approach is proposed and compared with the H_2/H_∞control by means of an application example

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