Wavelet domain control of rotor vibration

2006 ◽  
Vol 220 (2) ◽  
pp. 167-184 ◽  
Author(s):  
M O T Cole ◽  
P S Keogh ◽  
C R Burrows ◽  
M N Sahinkaya
Keyword(s):  
Steady State ◽  
Iterative Solution ◽  
Multiple Scale ◽  
Dynamic State ◽  
Linear Matrix ◽  
Control Force ◽  
Wavelet Coefficients ◽  
Rotor Vibration ◽  
Transient Vibration ◽  
Loop Control

This paper describes a novel application of the real-time wavelet transform in the control of rotor vibration. Vibration signal wavelet coefficients that relate to different time scales provide direct information on the system dynamic state, and can thus be used for feedback in a closed-loop control strategy that attenuates both transient and steady-state vibration components. Control force signals are synthesized from basis functions having a characteristic frequency and spacing interval closely matched to the rotational frequency. The control signal basis coefficients are generated by integral feedback of the wavelet coefficients such that under steady-state conditions the control forces eliminate measured rotor vibration. The controller synthesis problem is solved by iterative solution of a linear matrix inequality to obtain a gain matrix that satisfies H∞ norm-bound specifications for transient vibration attenuation. It is demonstrated experimentally that wavelet coefficients from multiple scale levels can be used in direct feedback to reduce levels of transient vibration caused by instantaneous changes in unbalance.

Synthesis of Robust Gain Matrices for Adaptive Rotor Vibration Control

1997 ◽  
Vol 119 (2) ◽  
pp. 298-300 ◽  
Author(s):  
C. R. Knospe ◽  
S. M. Tamer ◽  
S. J. Fedigan
Keyword(s):  
Steady State ◽  
Control Strategy ◽  
Synthesis Method ◽  
Open Loop ◽  
Active Magnetic Bearings ◽  
Open Loop Control ◽  
Rotor Vibration ◽  
Loop Control ◽  
Structured Uncertainty ◽  
Steady State Performance

Experimental results have recently demonstrated that an adaptive open-loop control strategy can be highly effective in the suppression of the unbalance induced vibration of rotors supported in active magnetic bearings. A synthesis method is presented for determining the adaptive law’s gain matrix such that the adaptation’s stability and steady-state performance are robust with respect to structured uncertainty.

Rotor vibration with auxiliary bearing contact in magnetic bearing systems Part 2: Robust synchronous control for rotor position recovery

2003 ◽  
Vol 217 (4) ◽  
pp. 393-409 ◽  
Author(s):  
M O T Cole ◽  
P S Keogh
Keyword(s):  
Position Control ◽  
Linear Time ◽  
Control Strategies ◽  
Magnetic Bearing ◽  
Contact Forces ◽  
Theoretical Modelling ◽  
Control Force ◽  
Rotor Vibration ◽  
Loop Control ◽  
Rotor Position

A number of conditions or events may produce rotor motion that involves contact with auxiliary bearings. Standard adaptive and closed-loop control strategies based on linear dynamics can cause instability when contact occurs, resulting in increased contact forces and vibration compared with the uncontrolled case. This paper introduces a method for robust control of synchronous vibration components that can maintain dynamic stability during interaction between the rotor and auxiliary bearings. The controllers are designed to minimize the severity and duration of contact and ensure that the rotor vibration returns to optimal levels, provided that sufficient control force capacity is available. Synthesis of controller gain matrices is based on a linear time-varying system model, which can be derived from either on-line identification routines or theoretical modelling and simulation. The controllers are tested experimentally on a flexible rotor system with magnetic bearings and are shown to restore rotor position control to optimal levels without further contact.

scholarly journals Influence of Time Delay on Controlling the Non-Linear Oscillations of a Rotating Blade

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 85
Author(s):  
Yasser Salah Hamed ◽  
Ali Kandil
Keyword(s):  
Time Delay ◽  
Natural Frequency ◽  
Multiple Scales ◽  
Control Process ◽  
Control Force ◽  
Specific Level ◽  
Loop Control ◽  
Positive Displacement ◽  
Non Linear ◽  
Linear Vibrations

Time delay is an obstacle in the way of actively controlling non-linear vibrations. In this paper, a rotating blade’s non-linear oscillations are reduced via a time-delayed non-linear saturation controller (NSC). This controller is excited by a positive displacement signal measured from the sensors on the blade, and its output is the suitable control force applied onto the actuators on the blade driving it to the desired minimum vibratory level. Based on the saturation phenomenon, the blade vibrations can be saturated at a specific level while the rest of the energy is transferred to the controller. This can be done by adjusting the controller natural frequency to be one half of the blade natural frequency. The whole behavior is governed by a system of first-order differential equations gained by the method of multiple scales. Different responses are included to show the influences of time delay on the closed-loop control process. Also, a good agreement can be noticed between the analytical curves and the numerically simulated ones.

Optimized Design of Vibration Controllers for Steady and Transient Excitation of Flexible Rotors

1995 ◽  
Vol 209 (3) ◽  
pp. 155-168 ◽  
Author(s):  
P S Keogh ◽  
C Mu ◽  
C R Burrows
Keyword(s):  
Measurement Error ◽  
Controller Design ◽  
Optimized Design ◽  
Rotor Vibration ◽  
Transient Vibration ◽  
Flexible Rotors ◽  
Vibration Attenuation ◽  
Measured Displacement ◽  
Control Forces ◽  
Shaft Surface

Controller designs for the attenuation of rotor vibration are investigated. Disturbance inputs leading to vibration are classified and related to control forces and defined control states. Optimization based on the H∞ norm is then used to minimize the influence of forcing disturbances, modelling error and measurement error. The practicalities of applying the method to an experimental rotor-bearing system, with hardware constraints on controller order, are stated. The controller was implemented experimentally to conduct steady state and mass loss tests. Steady synchronous, non-synchronous and transient vibration attenuation was demonstrated. It was also shown that measurement error, caused by shaft surface roughness, can be incorporated into the controller design without the need to remove the roughness component from the measured displacement signals. If the roughness influence is not included in the design and the uncontrolled vibration is small, unnecessary control forces may result, causing an increase in vibration.

Vibration Behavior and Serviceability of Arched Prestressed Concrete Truss Due to Human Activity

2018 ◽  
Vol 18 (12) ◽  
pp. 1850146 ◽  
Author(s):  
Jiang Li ◽  
Jiepeng Liu ◽  
Liang Cao ◽  
Y. Frank Chen
Keyword(s):  
Steady State ◽  
Prestressed Concrete ◽  
Natural Frequencies ◽  
Current Trend ◽  
Threshold Values ◽  
Transient Vibration ◽  
Vibration Behavior ◽  
Detailed Evaluation ◽  
Floor Systems ◽  
Floor Vibration

The current trend toward longer spans and lighter floor systems, combined with reduced damping and new activities, have resulted in an increasing complaints on floor vibration from building owners and occupants. Heel-drop, jumping, and walking impacts, which may lead to discomfort problems in daily life, were imposed on a large-span arched prestressed concrete truss (APT) girder system studied. The natural frequencies, peak acceleration, average root-mean-square acceleration (ARMS), maximum transient vibration value (MTVV), and perception factor for the girder were obtained and checked against the existing codes and standards. The purpose of this paper is to provide researchers and engineers with a detailed evaluation on the vibration behavior of the APT girder under different human activities, with a comprehensive review on the relevant criteria and some suggestions. Lastly, the following threshold peak accelerations are suggested: 650[Formula: see text]mm/s2 for transient heel-drop impact, 1450[Formula: see text]mm/s2 for transient jumping impact, and 250[Formula: see text]mm/s2 for steady-state walking. In addition, the threshold values of 90[Formula: see text]mm/s2 and 50[Formula: see text]mm/s2 are suggested for MTVV and ARMS, respectively, under steady-state walking.

scholarly journals The sensorless control system for controlling the speed of direct current motor

2019 ◽  
Vol 16 (3) ◽  
pp. 1171
Author(s):  
Khac-Khiem Nguyen ◽  
Trong-Thang Nguyen
Keyword(s):  
Direct Current ◽  
Pid Controller ◽  
Closed Loop ◽  
Dc Motor ◽  
State Equation ◽  
Dynamic State ◽  
Estimation Model ◽  
Loop Control ◽  
Quality Of Control

<p>This research aims to propose an algorithm for controlling the speed of the Direct Current (DC) motor in the absence of the sensor of speed. Based on the initial mathematical model of DC motor, the authors build the dynamic state equation of DC motor, and then build an estimation model to determine the speed of the DC motor without a sensor. The advantages of the proposed method are demonstrated through the closed-loop control model using the PID controller. In order for the results to be objective, we assume that the parameters of the DC motor in the estimation model are not known correctly. The results show that the quality of control in the absence of a sensor is equivalent to the case with the sensor.</p>

Multi-State Transient Rotor Vibration Control Using Sampled Harmonics

2002 ◽  
Vol 124 (2) ◽  
pp. 186-197 ◽  
Author(s):  
P. S. Keogh ◽  
M. O. T. Cole ◽  
C. R. Burrows
Keyword(s):  
Magnetic Bearing ◽  
Measured Data ◽  
Rapid Decrease ◽  
Flexible Rotor ◽  
Rotor Vibration ◽  
Transient Vibration ◽  
Stability Boundaries ◽  
Vibration Attenuation ◽  
Harmonic Components ◽  
Bearing System

A technique is introduced to achieve transient vibration attenuation in a multi-input, multi-output flexible rotor/magnetic bearing system. The strategy employs feedback control of measured harmonic components of rotor vibration. Whereas previous harmonic controllers have been based only on steady state vibration characteristics, the new controller also incorporates the transient dynamics. The controller may still be designed from measured data and is determined from target transient vibrational responses arising from step changes in particular disturbances. Account is taken of delays arising from evaluation of harmonic components. Furthermore, stability boundaries for the controller are shown to have significant tolerance to measurement error. The controller is validated experimentally in a flexible rotor/magnetic bearing system and mass loss tests are used to demonstrate rapid decrease in vibration levels with near elimination of transient overshoot.

scholarly journals Optimal guaranteed cost filtering for Markovian jump discrete-time systems

2004 ◽  
Vol 2004 (1) ◽  
pp. 33-48 ◽  
Author(s):  
Magdi S. Mahmoud ◽  
Peng Shi
Keyword(s):  
Steady State ◽  
Discrete Time ◽  
Estimation Error ◽  
Linear Matrix ◽  
State Estimator ◽  
Markovian Jump ◽  
Markovian Jump Parameters ◽  
Discrete Time Systems ◽  
Linear State ◽  
Time Systems

This paper develops a result on the design of robust steady-state estimator for a class of uncertain discrete-time systems with Markovian jump parameters. This result extends the steady-state Kalman filter to the case of norm-bounded time-varying uncertainties in the state and measurement equations as well as jumping parameters. We derive a linear state estimator such that the estimation-error covariance is guaranteed to lie within a certain bound for all admissible uncertainties. The solution is given in terms of a family of linear matrix inequalities (LMIs). A numerical example is included to illustrate the theory.

scholarly journals Fuzzy Controllers for Nonaffine-in-Control Singularly Perturbed Switched Systems

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Linna Zhou ◽  
Qianjin Wang ◽  
Xiaoping Ma ◽  
Chunyu Yang
Keyword(s):  
Switched Systems ◽  
Fuzzy Controller ◽  
Controller Design ◽  
Design Method ◽  
Singularly Perturbed ◽  
Dynamic State ◽  
Linear Matrix ◽  
Closed Loop System ◽  
Stability Bound ◽  
Takagi Sugeno

This paper investigates the problem of fuzzy controller design for nonaffine-in-control singularly perturbed switched systems (NCSPSSs). First, the NCSPSS is approximated by Takagi-Sugeno (T-S) models which include not only state but also control variables in the premise part of the rules. Then, a dynamic state feedback controller design method is proposed in terms of linear matrix inequalities. Under the controller, stability bound estimation problem of the closed-loop system is solved. Finally, an example is given to show the feasibility and effectiveness of the obtained methods.

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