Modelling and Parameter Identification for a Flexible Rotor With Periodic Impacts

2021 ◽  
Author(s):  
Stefan Holzinger ◽  
Manuel Schieferle ◽  
Johannes Gerstmayr ◽  
Manfred Hofer ◽  
Christoph Gutmann
Keyword(s):  
Measurement Data ◽  
Rotor System ◽  
Real System ◽  
Model Parameters ◽  
Genetic Optimization ◽  
Flexible Rotor ◽  
Unknown Parameters ◽  
System Parameters ◽  
Unknown System ◽  
The Impact

Abstract The ability of a multibody dynamics model to accurately predict the behavior of a real system depends heavily on the correct choice of model parameters. The identification of unknown system parameters, which cannot be directly computed or measured is usually time consuming and costly. If experimental measurement data of the real system is available, the parameters in the mathematical model can be determined by minimizing the error between the model response and the measurement data. The latter task can be solved by means of optimization. While many optimization methods are available, optimization with a genetic algorithm is a promising approach for searching optimal solutions for complex engineering problems, as reported in a paper of one of the authors. So far, however, there is no general approach how to apply genetic optimization algorithms for complex multibody system dynamics models in order to obtain unknown parameters automatically — which is however of great importance when dealing with real flexible multibody systems. In the present paper we present a methodology to determine several unknown system parameters applied to a flexible rotor system which is excited with periodic impacts. Experiments were performed on the physical system to obtain measurement data which is used to identify the impact force as well as the support stiffnesses of the rotor system using genetic optimization.

scholarly journals Dynamic torque calibration by means of model parameter identification

ACTA IMEKO ◽  
2015 ◽  
Vol 4 (2) ◽  
pp. 39 ◽  
Author(s):  
Leonard Klaus ◽  
Barbora Arendacká ◽  
Michael Kobusch ◽  
Thomas Bruns
Keyword(s):  
Frequency Response ◽  
Dynamic Behaviour ◽  
Measurement Data ◽  
Model Parameters ◽  
Dynamic Calibration ◽  
Extended Model ◽  
Unknown Parameters ◽  
Measuring Device ◽  
Torque Transducer ◽  
Least Squares Approach

For the dynamic calibration of torque transducers, a model of the transducer and an extended model of the mounted transducer including the measuring device have been developed. The dynamic behaviour of a torque transducer under test is going to be described by its model parameters. This paper describes the models with these known and unknown parameters and how the calibration measurements are going to be carried out. The principle for the identification of the transducer's model parameters from measurement data is described using a least squares approach. The influence of a variation of the transducer's parameters on the frequency response of the expanded model is analysed.

scholarly journals Impact of Damping Models in Damage Identification

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Michael Souza ◽  
Daniel Castello ◽  
Ney Roitman ◽  
Thiago Ritto
Keyword(s):  
Computational Models ◽  
Damage Identification ◽  
Model Parameters ◽  
Posterior Density ◽  
Unknown Parameters ◽  
Key Issues ◽  
Delayed Rejection ◽  
Lumped Masses ◽  
Aluminum Beam ◽  
The Impact

Several damage identification approaches are based on computational models, and their diagnostics depend on the set of modelling hypotheses adopted when building the model itself. Among these hypotheses, the choice of appropriate damping models seems to be one of the key issues. The goal of this paper is to analyze the impact of a set of damping models on the damage identification diagnostics. The damage identification is built on a Bayesian framework, and the measured data are the modal data associated with the first modes of the structure. The exploration of the posterior density of unknown model parameters is performed by means of the Markov chain Monte Carlo method (MCMC) with Delayed Rejection Adaptive Metropolis (DRAM) algorithm. The analyses are based on experimental dynamic response obtained from an aluminum beam instrumented with a set of accelerometers. The presence of damage/anomaly within the system is physically simulated by placing lumped masses over the beam, considering three different masses and two different placing positions. For the set of cases analyzed, it is shown that the proposed approach was able to identify both the position and magnitude of the lumped masses and that the damping models may not provide an increase of knowledge of some unknown parameters when damping rates are lower than 1%.

Assessment of Workspace Attributes Under Simulated Index Finger Proximal Interphalangeal Arthrodesis

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Paul G. Arauz ◽  
Sue A. Sisto ◽  
Imin Kao
Keyword(s):  
Index Finger ◽  
Model Parameters ◽  
System Parameters ◽  
System A ◽  
Flexion Extension ◽  
Pip Joint ◽  
Interphalangeal Arthrodesis ◽  
Analysis System ◽  
The Impact ◽  
Proximal Interphalangeal Arthrodesis

This article presented an assessment of quantitative measures of workspace (WS) attributes under simulated proximal interphalangeal (PIP) joint arthrodesis of the index finger. Seven healthy subjects were tested with the PIP joint unconstrained (UC) and constrained to selected angles using a motion analysis system. A model of the constrained finger was developed in order to address the impact of the inclusion of prescribed joint arthrodesis angles on WS attributes. Model parameters were obtained from system identification experiments involving flexion–extension (FE) movements of the UC and constrained finger. The data of experimental FE movements of the constrained finger were used to generate the two-dimensional (2D) WS boundaries and to validate the model. A weighted criterion was formulated to define an optimal constraint angle among several system parameters. Results indicated that a PIP joint immobilization angle of 40–50 deg of flexion maximized the 2D WS. The analysis of the aspect ratio of the 2D WS indicated that the WS was more evenly distributed as the imposed PIP joint constraint angle increased. With the imposed PIP joint constraint angles of 30 deg, 40 deg, 50 deg, and 60 deg of flexion, the normalized maximum distance of fingertip reach was reduced by approximately 3%, 4%, 7%, and 9%, respectively.

Vibration and Control of a Flexible Rotor in Magnetic Bearings Using Hybrid Method and H∞ Control Theory

1997 ◽  
Vol 119 (1) ◽  
pp. 178-185 ◽  
Author(s):  
T. N. Shiau ◽  
G. J. Sheu ◽  
C. D. Yang
Keyword(s):  
Control Theory ◽  
Hybrid Method ◽  
Control Design ◽  
Expansion Method ◽  
Rotor System ◽  
Magnetic Bearings ◽  
Experimental Simulation ◽  
Model Parameters ◽  
Flexible Rotor ◽  
H2 Control

The vibration and active control of a flexible rotor system with magnetic bearings are investigated using Hybrid Method (HM) and H∞ control theory with consideration of gyroscopic effect. The hybrid method, which combines the merits of the finite element method (FEM) and generalized polynomial expansion method (GPEM) is employed to model the flexible rotor system with small order of plant. The mixed sensitivity problem of H∞ control theory is applied to design the control of system vibration with spillover phenomena for the reduced order plant. The H2 control design is also employed for comparison with the H∞ design. The experimental simulation is used to illustrate the effects of control design. It is shown that the H∞ controller design can be very effective to suppress spillover phenomena. In addition, the H∞ control design has robustness to the variation of the model parameters. The application of the hybrid method (HM) together with H∞ control design is highly recommended for vibration control of flexible rotor systems with magnetic bearings.

scholarly journals Parameter Identification With Noncollocation of Force and Measurement Locations Using Nonsynchronous Perturbation and Optimization Techniques

1994 ◽  
Author(s):  
Wesley D. Franklin ◽  
Agnes Muszynska ◽  
Donald E. Bently
Keyword(s):  
Finite Element ◽  
Computer Program ◽  
Parameter Identification ◽  
Dynamic Stiffness ◽  
Rotor System ◽  
Optimization Techniques ◽  
Perturbation Techniques ◽  
Unknown Parameters ◽  
System Parameters ◽  
Applied Forces

Nonsynchronous perturbation techniques developed over the last few years have proven to be a very powerful tool for parameter identification of rotating systems. In order to obtain interpretable results, some limitations have had to be imposed on the analytical models and rotor systems used in the process, such as applied forces, and measurement transducers had to be located near major masses on the rotor. In the laboratory environment these limitations can usually be accommodated, but not always, while in the field, compliance is almost impossible. This paper explores the use of finite element modeling, measured vibration response data, and optimization techniques to extend the applicability of parameter identification through nonsynchronous perturbation techniques to those systems in which the perturbation forces and/or resultant response measurements cannot be conveniently located at the mass centers. In this technique, a finite element model of the rotor system is constructed, and all known information about the system parameters input to a computer program designed to operate on a personal computer. The program then computes the theoretical response of the system, by processing user-supplied initial conditions for the unknown system parameters, and compares these results with the vibration responses measured on the machine, and collected by the data acquisition system. The unknown parameters are then modified using local convergence optimization techniques until the error between the theoretical and measured responses is acceptably small. If the system parameters under investigation coincide with the unknown parameters in the computer program, they are identified in the process. This technique was applied to an experimental rotor system constructed such that the parameters under investigation, the direct and quadrature dynamic stiffness components for a plain oil-lubricated journal bearing operating at low eccentricity, could be determined by both this technique and conventional unbalance force testing. The results of the nonsynchronous tests are presented in the paper.

Sensitivity Analysis of Concrete Face Rock-Fill Dam Parametric Based on the Intelligent Algorithm

2014 ◽  
Vol 580-583 ◽  
pp. 1940-1945
Author(s):  
Qiao Yan ◽  
Zhan Hong Gao ◽  
Zhi Cheng Song
Keyword(s):  
Sensitivity Analysis ◽  
Orthogonal Design ◽  
Model Parameters ◽  
Analysis Method ◽  
Range Analysis ◽  
Unknown Parameters ◽  
Rock Fill ◽  
Dam Deformation ◽  
Parameters Inversion ◽  
The Impact

Sensitivity analysis of model parameters is a rock fill parametric inversion analysis method to determine the unknown parameters. Traditional sensitivity analysis is basically a lot of trial or the method of single factor analysis based on a large amount of calculation, but, unable to reflect the real situation. The method of particle swarm optimization based on neural network based nonlinear mapping relationship between model parameters and displacement to finite element simulation of dam deformation. Basing on the orthogonal design, the methods of range analysis and variance analysis method were used for sensitivity analysis of the parameters of Duncan E-B model and the impact of various parameters on the dam displacement, and then it can be as the parameters of rock fill dam provide basis for determining the unknown parameters inversion.

Decoupling Vibration Control of a Flexible Rotor System with Symmetric Mass and Stiffness Properties

1993 ◽  
Vol 207 (1) ◽  
pp. 9-14 ◽  
Author(s):  
S T Chen ◽  
A C Lee
Keyword(s):  
Control Algorithm ◽  
Controller Design ◽  
Rotor System ◽  
Decoupling Control ◽  
Flexible Rotor ◽  
System Parameters ◽  
Stiffness Properties ◽  
Control Scheme ◽  
Gyroscopic Effects ◽  
Modal Space

The paper investigates the control problem for a flexible rotor system with symmetric mass and stiffness properties and proposes an internal and external decoupling control scheme to simplify the controller design for such a system, where the existence of gyroscopic effects during rotation is neglected. The whole flexible rotor system can eventually be separated into four flexible subsystems without knowledge of the system parameters, and the control algorithm for each subsystem can be designed and implemented independently. Simulation results demonstrate the effectiveness of using the proposed scheme in conjunction with the optimal modal space control scheme.

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

2019 ◽  
Vol 2019 (1) ◽  
pp. 331-338 ◽  
Author(s):  
Jérémie Gerhardt ◽  
Michael E. Miller ◽  
Hyunjin Yoo ◽  
Tara Akhavan
Keyword(s):  
Image Processing ◽  
Power Consumption ◽  
Model Parameters ◽  
Display Device ◽  
Image Processing Algorithm ◽  
Pixel Value ◽  
Device Lifetime ◽  
The Impact ◽  
Oled Display

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

scholarly journals Modeling of German Low Voltage Cables with Ground Return Path

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1265 ◽  
Author(s):  
Johanna Geis-Schroer ◽  
Sebastian Hubschneider ◽  
Lukas Held ◽  
Frederik Gielnik ◽  
Michael Armbruster ◽  
...  
Keyword(s):  
Low Voltage ◽  
Measurement Data ◽  
Analytical Calculation ◽  
Laboratory Measurement ◽  
Model Parameters ◽  
Calculation Methods ◽  
Modeling Approach ◽  
Measurement Results ◽  
Simulation Results ◽  
Return Path

In this contribution, measurement data of phase, neutral, and ground currents from real low voltage (LV) feeders in Germany is presented and analyzed. The data obtained is used to review and evaluate common modeling approaches for LV systems. An alternative modeling approach for detailed cable and ground modeling, which allows for the consideration of typical German LV earthing conditions and asymmetrical cable design, is proposed. Further, analytical calculation methods for model parameters are described and compared to laboratory measurement results of real LV cables. The models are then evaluated in terms of parameter sensitivity and parameter relevance, focusing on the influence of conventionally performed simplifications, such as neglecting house junction cables, shunt admittances, or temperature dependencies. By comparing measurement data from a real LV feeder to simulation results, the proposed modeling approach is validated.

scholarly journals Empirical Stochastic Model of Multi-GNSS Measurements

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4566
Author(s):  
Dominik Prochniewicz ◽  
Kinga Wezka ◽  
Joanna Kozuchowska
Keyword(s):  
Stochastic Model ◽  
Density Ratio ◽  
Functional Model ◽  
Optimal Solution ◽  
Global Navigation Satellite Systems ◽  
Unknown Parameters ◽  
Short Baseline ◽  
Stochastic Parameters ◽  
Dependent Model ◽  
The Impact

The stochastic model, together with the functional model, form the mathematical model of observation that enables the estimation of the unknown parameters. In Global Navigation Satellite Systems (GNSS), the stochastic model is an especially important element as it affects not only the accuracy of the positioning model solution, but also the reliability of the carrier-phase ambiguity resolution (AR). In this paper, we study in detail the stochastic modeling problem for Multi-GNSS positioning models, for which the standard approach used so far was to adopt stochastic parameters from the Global Positioning System (GPS). The aim of this work is to develop an individual, empirical stochastic model for each signal and each satellite block for GPS, GLONASS, Galileo and BeiDou systems. The realistic stochastic model is created in the form of a fully populated variance-covariance (VC) matrix that takes into account, in addition to the Carrier-to-Noise density Ratio (C/N0)-dependent variance function, also the cross- and time-correlations between the observations. The weekly measurements from a zero-length and very short baseline are utilized to derive stochastic parameters. The impact on the AR and solution accuracy is analyzed for different positioning scenarios using the modified Kalman Filter. Comparing the positioning results obtained for the created model with respect to the results for the standard elevation-dependent model allows to conclude that the individual empirical stochastic model increases the accuracy of positioning solution and the efficiency of AR. The optimal solution is achieved for four-system Multi-GNSS solution using fully populated empirical model individual for satellite blocks, which provides a 2% increase in the effectiveness of the AR (up to 100%), an increase in the number of solutions with errors below 5 mm by 37% and a reduction in the maximum error by 6 mm compared to the Multi-GNSS solution using the elevation-dependent model with neglected measurements correlations.

Sign in / Sign up

Export Citation Format

Share Document