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.

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.

Closed-Loop Vibration Control of Flexible Rotors—An Experimental Study

1993 ◽  
Vol 207 (1) ◽  
pp. 1-17 ◽  
Author(s):  
C R Burrows ◽  
P S Keogh ◽  
R Tasaltin
Keyword(s):  
Experimental Study ◽  
Vibration Control ◽  
State Feedback ◽  
Closed Loop ◽  
Dominant Mode ◽  
Pole Placement ◽  
Magnetic Actuator ◽  
Flexible Rotors ◽  
Measured Displacement ◽  
Control Forces

An experimental study has been made for the synchronous vibration control of a rotor-bearing system using a magnetic actuator to supply the control forces. Both open- and closed-loop strategies were implemented using measured displacement signals from various transducer configurations. Model reduction based on dominant mode methods was used to aid the design of the closed-loop strategies. These were based on pole placement techniques. It was shown that state feedback, without co-location of sensors and actuator, can be used to suppress critical speed responses without encountering spillover problems. The robustness of the strategies was also assessed by deleting selected feedback paths.

Optimal Design of Squeeze Film Supports for Flexible Rotors

1983 ◽  
Vol 105 (3) ◽  
pp. 487-494 ◽  
Author(s):  
M. D. Rabinowitz ◽  
E. J. Hahn
Keyword(s):  
Optimal Design ◽  
Vibration Amplitude ◽  
Operating Conditions ◽  
Squeeze Film ◽  
Rotor Vibration ◽  
Design Constraints ◽  
Supply Pressure ◽  
Flexible Rotors ◽  
Wide Range ◽  
Film Lubrication

Assuming central preloading, operation below the second bending critical speed, and full film lubrication, this paper presents a theoretical model which allows one, with minimum computation, to design squeeze film damped rotors under conditions of high unbalance loading. Closed form expressions are derived for the maximum vibration amplitudes pertaining to optimally damped conditions. The resulting vibration amplitude and transmissibility data of design interest are presented for a wide range of practical operating conditions on a single chart. It can be seen that for a given rotor, the lighter the bearing the more easily one can satisfy design constraints relating to allowable rotor vibration levels and lubricant supply pressure requirements. The data presented are shown to be applicable to a wide variety of rotors, and a recommended procedure for optimal design is outlined.

Rotor vibration with auxiliary bearing contact in magnetic bearing systems Part 1: Synchronous dynamics

2003 ◽  
Vol 217 (4) ◽  
pp. 377-392 ◽  
Author(s):  
P S Keogh ◽  
M O T Cole
Keyword(s):  
Position Control ◽  
Magnetic Bearing ◽  
Physical Interaction ◽  
Flexible Rotor ◽  
Rotor Vibration ◽  
Full Control ◽  
Flexible Rotors ◽  
Bearing Contact ◽  
Auxiliary Bearing ◽  
Control Capability

Magnetic bearing systems incorporate auxiliary bearings to prevent physical interaction between rotor and stator laminations. Rotor/auxiliary bearing contacts may occur when a magnetic bearing still retains a full control capability. To actively return the rotor to a non-contacting state it is essential to determine the manner in which contact events affect the rotor vibration signals used for position control. An analytical procedure is used to assess the nature of rotor contact modes under idealized contacts. Non-linearities arising from contact and magnetic bearing forces are then included in simulation studies involving rigid and flexible rotors to predict rotor response and evaluate rotor synchronous vibration components. An experimental flexible rotor/magnetic bearing facility is also used to validate the predictions. It is shown that changes in synchronous vibration amplitude and phase induced by contact events causes existing controllers to be ineffective in attenuating rotor displacements. These findings are used in Part 2 of the paper as a foundation for the design of new controllers that are able to recover rotor position control under a range of contact cases.

scholarly journals Performance of an Electromagnetic Bearing for the Vibration Control of a Supercritical Shaft

1987 ◽  
Vol 201 (3) ◽  
pp. 201-212 ◽  
Author(s):  
C D Bradfield ◽  
J B Roberts ◽  
R Karunendiran
Keyword(s):  
Vibration Control ◽  
Control Algorithm ◽  
Control Strategies ◽  
Single Point ◽  
Test Rig ◽  
Rotating Shaft ◽  
Linear Spring ◽  
Measured Displacement ◽  
Control Forces ◽  
Electromagnetic Bearing

The flexural vibrations of a rotating shaft, running through one or more critical speeds, can be reduced to an acceptably low level by applying suitable control forces at an intermediate span position. If electromagnets are used to produce the control forces then it is possible to implement a wide variety of control strategies. A test rig is described which includes a microprocessor-based controller, in which such strategies can be realized in terms of software-based algorithms. The electromagnet configuration and the method of stabilizing the electromagnet force–gap characteristic are discussed. The bounds on the performance of the system are defined. A simple control algorithm is outlined, where the control forces are proportional to the measured displacement and velocity at a single point on the shaft span; in this case the electromagnet behaves in a similar manner to that of a parallel combination of a linear spring and damper. Experimental and predicted performances of the system are compared, for this type of control, where various programmable rates of damping are applied.

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.

scholarly journals Vibration-Attenuation Controller Design for Uncertain Mechanical Systems with Input Time Delay

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yuanchun Ding ◽  
Falu Weng ◽  
Xiaohua Jiang ◽  
Minkang Tang
Keyword(s):  
Closed Loop ◽  
Controller Design ◽  
State Space Model ◽  
Mechanical Systems ◽  
Sufficient Conditions ◽  
Uncertain System ◽  
Disturbance Attenuation ◽  
System Model ◽  
Closed Loop System ◽  
Vibration Attenuation

The problems of vibration-attenuation controller design for uncertain mechanical systems with time-varying input delay are of concern in this paper. Firstly, based on matrix transformation, the mechanical system is described as a state-space model. Then, in terms of introducing the linear varying parameters, the uncertain system model is established. Secondly, the LMI-based sufficient conditions for the system to be stabilizable are deduced by utilizing the LMI technique. By solving the obtained LMIs, the controllers are achieved for the closed-loop system to be stable with a prescribed level of disturbance attenuation. Finally, numerical examples are given to show the effectiveness of the proposed theorems.

Optimal State Feedback Controller Design for Vibration Attenuation in a Class of Image Transfer Belt

2015 ◽  
Vol 789-790 ◽  
pp. 918-922
Author(s):  
Jie Yu ◽  
Hiroshi Yamaura
Keyword(s):  
State Feedback ◽  
Controller Design ◽  
Satisfying Condition ◽  
Feedback Controller ◽  
Image Transfer ◽  
Optimal State ◽  
State Feedback Controller ◽  
Periodic Loading ◽  
Vibration Attenuation ◽  
Optimal State Feedback

An optimal state feedback controller based on H2 norm is proposed for attenuating the belt vibration caused by loading disturbance in a class of image transfer belt which is widely applied in multi-color printers. Based on the simplified mechanical model of the image transfer belt unit, the presented controller acts on the actuating torque generated by a direct-current motor and optimizes the defined variables related to the quality of the original image formation. Simulation results responding to a periodic loading disturbance ascertain its efficacy with comparisons of the conventional speed control. It is certified that the image transfer belt unit is successfully maintained in a satisfying condition with effective vibration attenuation under the proposed control architecture.

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