scholarly journals On the oscillatory behaviours and rub-impact forces of a horizontally supported asymmetric rotor system under position-velocity feedback controller

2021 ◽  
Vol 18 (2) ◽  
Author(s):  
N. A. Saeed ◽  
S. I. El-Bendary ◽  
M. Sayed ◽  
M. S. Mohamed ◽  
S. K. Elagan
Keyword(s):  
Rotor System ◽  
Feedback Controller ◽  
Velocity Feedback ◽  
Impact Forces ◽  
Asymmetric Rotor

scholarly journals Rub-Impact Force Induces Periodic, Quasiperiodic, and Chaotic Motions of a Controlled Asymmetric Rotor System

2021 ◽  
Vol 2021 ◽  
pp. 1-27
Author(s):  
N. A. Saeed ◽  
Emad Mahrous Awwad ◽  
Ali Maarouf ◽  
Hassan M. H. Farh ◽  
Fahd A. Alturki ◽  
...  
Keyword(s):  
Impact Force ◽  
Equations Of Motion ◽  
Rotor System ◽  
Control Law ◽  
Slow Flow ◽  
Response Curves ◽  
Chaotic Motions ◽  
Flow Equations ◽  
Impact Forces ◽  
Asymmetric Rotor

This article aims to explore the oscillatory characteristics of a controlled asymmetric rotor system when subjected to rub and impact forces between the rotor and stator. Four electromagnetic poles are used to control the whirling motion of the rotor system through a linear proportional-derivative control law. The equations of motion that govern the whole system dynamics are derived including the rub and impact forces. The derived mathematical model is analyzed in two basic steps. Firstly, the obtained model is treated as a weakly nonlinear system using perturbation analysis to obtain the slow-flow modulating equations when neglecting the rub and impact forces. Depending on the obtained slow-flow equations, different response curves are plotted to explore the system’s periodic vibrations and determine the conditions at which the system can exhibit rub and impact force. Secondly, the whole system model including the rub and impact forces is investigated by using the bifurcation diagrams, Poincare map, frequency spectrums, and temporal oscillations. The obtained results revealed that the applied control law could mitigate the system whirling oscillations and prevent the rub and impact forces if the control gains are tuned properly. However, the system can perform period-n, quasiperiodic, or chaotic motion depending on the shaft spinning speed if the controller fails to eliminate the contact between the rotor and stator.

scholarly journals Experimental Verifications of Vibration Suppression for a Smart Cantilever Beam with a Modified Velocity Feedback Controller

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Ting Zhang ◽  
Hong Guang Li ◽  
Guo Ping Cai ◽  
Fu Cai Li
Keyword(s):  
Free Vibration ◽  
State Feedback ◽  
Vibration Suppression ◽  
State Observer ◽  
Feedback Controller ◽  
Extended State Observer ◽  
Feedback Gain ◽  
Flexible Beam ◽  
Extended State ◽  
Velocity Feedback

This paper presents various experimental verifications for the theoretical analysis results of vibration suppression to a smart flexible beam bonded with a piezoelectric actuator by a velocity feedback controller and an extended state observer (ESO). During the state feedback control (SFC) design process for the smart flexible beam with the pole placement theory, in the state feedback gain matrix, the velocity feedback gain is much more than the displacement feedback gain. For the difference between the velocity feedback gain and the displacement feedback gain, a modified velocity feedback controller is applied based on a dynamical model with the Hamilton principle to the smart beam. In addition, the feedback velocity is attained with the extended state observer and the displacement is acquired by the foil gauge on the root of the smart flexible beam. The control voltage is calculated by the designed velocity feedback gain multiplied by the feedback velocity. Through some experiment verifications for simulation results, it is indicated that the suppressed amplitude of free vibration is up to 62.13% while the attenuated magnitude of its velocity is up to 61.31%. Therefore, it is demonstrated that the modified velocity feedback control with the extended state observer is feasible to reduce free vibration.

Study on the Dynamic Response of an Unbalanced Rotor System Supported by Ball Bearings

2019 ◽  
Author(s):  
Bin Fang ◽  
Jinhua Zhang ◽  
Ke Yan ◽  
Jun Hong
Keyword(s):  
Dynamic Model ◽  
Ball Bearing ◽  
Great Influence ◽  
Rotor System ◽  
Dynamic Responses ◽  
Ball Bearings ◽  
Motion Patterns ◽  
Symmetric Rotor ◽  
Asymmetric Rotor ◽  
Restoring Forces

Abstract This paper proposed a new four-degree-of-freedom dynamic model of the bearing-rotor system based on ball bearing without Raceway Control Hypothesis, and both the inertia forces of balls and the tilting motions of rotor are fully considering in the calculation of restoring forces and moments of ball bearings. Then the dynamic model are solved by the fourth-step Runge-Kutta method, and the dynamic responses of rotor system including the displacement, velocity and center orbits are obtained, and the influences of rotating speeds, eccentricity and symmetry of rotor are studied and analyzed. The results show that both the varying compliance of ball bearing and rotor eccentric force have a great influence on the dynamic responses and motion patterns of bearing-rotor system, and the titling motion of bearing-rotor should be considered in the analysis of asymmetric rotor or the symmetric rotor under some specific conditions.

scholarly journals A Study of Integrally Augmented State Feedback Control for an Active Magnetic Bearing Supported Rotor System

1997 ◽  
Author(s):  
George T. Flowers ◽  
Gyorgy Szasz ◽  
Victor S. Trent ◽  
Michael E. Greene
Keyword(s):  
State Feedback ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Feedback Controller ◽  
State Feedback Control ◽  
Pole Placement ◽  
State Feedback Controller ◽  
System Type ◽  
Effective Manner ◽  
Augmented State

State feedback controller designs allow for pole-placement in an effective manner, but reduction of static offset is difficult. On the other hand, classical control methodology allows for the increase of system type and the elimination of static offset. An integrally augmented state feedback controller provides the benefits of standard feedback designs while allowing for the elimination of static offsets (through the increase of system type). Static offset is a particular problem with magnetic bearing supported rotor systems, in that gravitational effects, current biasing, and operational loading tend to exacerbate this problem. In order to assess the effectiveness of this technique, an integrally augmented state feedback controller is developed, implemented, and tested for a magnetic bearing supported rotor system. Results for several selected configurations are presented and compared. Some conclusions and recommendations concerning the effectiveness of integrally augmented state feedback controller designs are presented.

Stabilizing and Positioning Control of Inverted Flexible Pendulum by Means of H∞ Servo Control With Partial-State Feedback

1995 ◽  
Author(s):  
Hidekazu Nishimura ◽  
Osamu Ohnuki ◽  
Kenzo Nonami ◽  
Takayoshi Totani
Keyword(s):  
Output Feedback ◽  
Feedback Loop ◽  
State Feedback ◽  
Feedback Controller ◽  
Step Response ◽  
Velocity Feedback ◽  
Positioning Control ◽  
Output Feedback Controller ◽  
Partial State ◽  
Settling Characteristics

Abstract In this study we formulate H∞ servo compensator where displacement signals are used as the controlled variables and their time derivatives are used as partial-state feedback signals for stabilizing and positioning control of a cart and inverted flexible pendulum system. The feedback loop of the part of the state variables except the controlled variables is added to the feedback loop of the controlled variables in the design of the H∞ compensator. Through this formulation the order of the designed compensator is reduced by the order of the weighting functions for the time derivative signals. By numerical calculations and experiments, we investigate the settling characteristics and the robust stability against a disturbance to the pendulum with two kinds of controllers, the output feedback controller by the displacement feedback and the output feedback controller adding the cart velocity feedback. It is shown that although the displacement-output feedback controller has a big overshoot in the step response and the positioning of the cart is difficult, by means of the partial-state feedback controller with a cart velocity feedback the overshoot can be reduced and stable positioning control of the cart is possible. Also it is verified that the servo compensator is superior to the regulator-based compensator in the settling characteristics.

PARAMETRIC INSTABILITY OF TWO-DISK ROTOR WITH TWO INERTIA ASYMMETRIES

2012 ◽  
Vol 12 (02) ◽  
pp. 251-284 ◽  
Author(s):  
Q. K. HAN ◽  
F. L. CHU
Keyword(s):  
Dynamic Instability ◽  
Parametric Instability ◽  
Rotor System ◽  
Operating Conditions ◽  
Design Parameters ◽  
Rotating Speed ◽  
Expansion Technique ◽  
Single Disk ◽  
Asymmetric Rotor ◽  
The One

Determination of operating conditions of parametric instability is crucial to the design and usage of the inertia asymmetric rotor. Current research mostly focused on the rotor with single inertia asymmetric disk. There are few studies on the multi-disk rotors with multiple inertia asymmetries. In fact, the interaction between the multiple parametric excitations with various phasing and amplitude, which are induced by the multiple unsymmetrical disks, would make the instability behavior of the system differ distinctly from that of the single-disk rotor system. Thus, the parametric instability of the two-disk rotor system with two inertia asymmetries is studied herein. Two important indicators for describing the unstable regions, namely the unstable rotating speed and width of the unstable region, are defined and derived using the parametric instability theory and Taylor expansion technique. For a practical used two-disk unsymmetrical rotor, three design parameters (inertia excitation phasing, relative position of the disk, and inertia ratio) are discussed in detail for their effects on the two indicators. It is shown from the results that the dynamic instability of the two-disk unsymmetrical rotor system indeed has some unique features that differ from that of the one-disk rotor system. The interaction of the two inertia parametric excitations could be utilized to control (or enhance) the unstable regions.

Dynamic Modeling of a Wheelchair on a Slope

1983 ◽  
Vol 105 (2) ◽  
pp. 101-106 ◽  
Author(s):  
J. B. Shung ◽  
G. Stout ◽  
M. Tomizuka ◽  
D. M. Auslander
Keyword(s):  
Experimental Data ◽  
Motor Control ◽  
Dynamic Modeling ◽  
Computer Model ◽  
Feedback Controller ◽  
Velocity Feedback ◽  
Sloping Surface

This paper describes a computer model of a wheelchair and its motor control circuitry. The model simulates the wheelchair’s motion in driving on a sloping surface, and is intended to facilitate the design of wheel velocity feedback controller. Experimental data are presented to partially validate the model.

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