Imbalance Estimation for Speed-Varying Rigid Rotors Using Time-Varying Observer

1999 ◽  
Vol 123 (4) ◽  
pp. 637-644 ◽  
Author(s):  
Shiyu Zhou ◽  
Jianjun Shi
Keyword(s):  
Active Vibration Control ◽  
Estimation Method ◽  
Time Varying ◽  
Rigid Rotor ◽  
Augmented System ◽  
Active Balancing ◽  
Active Vibration ◽  
Rotor Dynamic ◽  
Rigid Rotors ◽  
Rotor Model

Rigid rotor dynamic model is widely used to model rotating machinery. In this paper, a speed-varying transient rigid rotor model is developed in the state space form. The states of this model are augmented to include imbalance forces and moments. A time-varying observer can then be designed for the augmented system by using canonical transformation. After obtaining an estimation of the imbalance forces and moments as the states of the augmented system, the estimated imbalance can be directly calculated. This estimation method can be used in the active vibration control or active balancing schemes for a rigid rotor.

scholarly journals Extended Application Of Time-Varying Observer For Rigid Rotors Unbalance Estimation During Acceleration

2018 ◽  
Vol 167 ◽  
pp. 02015
Author(s):  
Xunxing Yu ◽  
Kuanmin Mao ◽  
Yaming Zhu
Keyword(s):  
State Space ◽  
Control Strategy ◽  
State Space Model ◽  
Time Varying ◽  
Rigid Rotor ◽  
Space Model ◽  
Active Balancing ◽  
Extended Application ◽  
Balancing Control ◽  
Rigid Rotors

Unbalance is one of essential problems for modern rotating machines. In this work, an improved time-varying observer is proposed to estimate the unbalance of rigid rotor during acceleration. In order to fitting different speed acceleration laws, the unbalance forces have been included in an new designed augmented states, meanwhile the state space model of rigid rotor has been also developed. The developed state space model is transformed to a canonical transformation and a new designed time-varying observer can be obtained. The estimated unbalances can be directly obtained by using this time-varying observer. This method would be very helpful for active balancing control strategy during acceleration.

Robust Active Vibration Control of a Bandsaw Blade

1999 ◽  
Vol 122 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Christopher J. Damaren ◽  
Lan Le-Ngoc
Keyword(s):  
Analytical Study ◽  
Active Vibration Control ◽  
State Space Model ◽  
Time Varying ◽  
Axial Motion ◽  
Exogenous Disturbances ◽  
Active Vibration ◽  
And Performance ◽  
Rate Sensor ◽  
Gyroscopic Effects

An analytical study of a vibrating bandsaw blade is presented. The blade is modeled as a plate translating over simply-supporting guides. Gyroscopic effects due to the blade’s axial motion as well as in-plane forces resulting from tensioning and the influence of the cutting force are included in the model. The latter is modeled as a nonconservative follower force on the cutting edge of the blade and shown to be destabilizing. A state-space model is developed which includes the effects of time-varying cutting forces and exogenous disturbances. Feedback control via a collocated force actuator/rate sensor is introduced and recent advances in robust control theory are used develop controllers which achieve robust stability and performance with respect to the time-varying model. [S0739-3717(00)01101-6]

Active vibration control of rotor-bearing system by virtual dynamic absorber

2019 ◽  
Vol 86 (3) ◽  
pp. 30901
Author(s):  
Behnam Monjezi ◽  
Hamidreza Heidari
Keyword(s):  
Transient Response ◽  
Control Method ◽  
Active Vibration Control ◽  
Resonance State ◽  
Rotor System ◽  
Manufacturing Defects ◽  
Resonance Frequencies ◽  
Active Vibration ◽  
Dynamic Absorber ◽  
Rotor Dynamic

The main sources of the vibration in rotor dynamic systems are unbalanced masses and manufacturing defects of bearings used in the rotor system. In this study, magnetic absorber as a new method brings the rotor system out of resonance state by applying a dynamic absorber system force and creating two new natural frequencies. This study virtually reconstructed magnetic absorber controller software as a combined active and passive dynamic absorber to reduce vibration amplitude, efficiently. In this approach, combined routes are defined for the rotor frequency response, so that the optimal values of the parameters of dynamic absorber system are calculated using H∞ method and maximum damping for frequencies lower and higher than resonance frequencies, respectively. The results confirm that transient response overshoot is less, and transient response attenuation is more in maximum damping method. Hence, the controller system easily recognizes initial overshoots and determines the parameters of the dynamic absorber system in accordance with maximum damping state if it is struck at any rotor frequency and any rotation angle. It is also observed that for all rotor rotation frequencies, the system overshoot reduces in comparison with H∞ method by using this control method.

Chaos of a Flexible Rotor in Journal Bearings

1995 ◽  
Author(s):  
R. D. Brown ◽  
G. Drummond
Keyword(s):  
Theoretical Models ◽  
Journal Bearings ◽  
Rotating Machinery ◽  
Rigid Rotor ◽  
Flexible Rotor ◽  
Hydrodynamic Bearings ◽  
Stress Reversals ◽  
Oil Films ◽  
Rigid Rotors ◽  
Rotor Model

Abstract Nonlinear systems can give rise to chaotic behaviour, essentially unpredictable. Oil film forces arising from hydrodynamic bearings in rotating machinery can be extremely nonlinear under conditions of large unbalance. Chaotic response has been demonstrated in theoretical models of rigid rotors supported in hydrodynamic bearings. The behaviour of a rigid rotor can be extended by looking at a flexible rotor model supported on journal bearings and subject to large unbalance levels. The introduction of a flexible shaft yields chaotic regions which are less extensive than those obtained from a rigid rotor model. This is not surprising as the nonlinearity in the model is confined to the oil films at the end of the shaft. However if this level of unbalance is experienced in service then shaft fatigue could occur because of the sustained nature of the non-synchronous response and the effect of the resulting stress reversals.

Robust Kalman-Filter-Based Frequency-Shaping Optimal Active Vibration Control of Uncertain Flexible Mechanical Systems with Nonlinear Actuators

2003 ◽  
Vol 9 (6) ◽  
pp. 623-644 ◽  
Author(s):  
Shinn-Horng Chen
Keyword(s):  
Vibration Control ◽  
Active Vibration Control ◽  
Time Varying ◽  
Time Varying Parameter ◽  
Robust Kalman Filter ◽  
Parameter Perturbations ◽  
Actuator Nonlinearities ◽  
Active Vibration ◽  
Control Methodology ◽  
Flexible Mechanical System

In this paper, we present a time-domain control methodology, called the robust Kalman-filter-based frequency-shaping optimal feedback (KFBFSOF) control method. Using this method, we treat the active vibration control (or active vibration suppression) problem of flexible mechanical systems under simultaneously high-frequency unmodeled dynamics, residual modes, linear time-varying parameter perturbations in both the controlled and residual parts, noises (input noise and measurement noise), noise uncertainties and actuator nonlinearities. Two robust stability conditions are proposed for the flexible mechanical system, which is controlled by a KFBFSOF controller and subject to mode truncation, noise uncertainties, actuator nonlinearities and linear structured time-varying parameter perturbations simultaneously. The advantage of the presented KFBFSOF control methodology is that it can make the controlled closed-loop system have both good robustness at high frequencies and good performance at low frequencies. Besides, the proposed robust stability criteria guarantee that the designed KFBFSOF controller can make the controlled flexible mechanical system avoid the possibilities of instability induced by both spillover and time-varying parameter perturbations. Two examples are given to illustrate the application of the presented control methodology to the active vibration control problems of a simply-supported flexible beam and of a flexible rotor system.

Sign in / Sign up

Export Citation Format

Share Document