Showing papers in "Journal of Vibration and Control in 2009"
TL;DR: In this article, a modified numerical scheme for a class of Frac- tional Optimal Control Problems (FOCPs) formulated in Agrawal (2004) where a fractional derivative (FD) is defined in the Riemann-Liouville sense is presented.
Abstract: This paper presents a modified numerical scheme for a class of Frac- tional Optimal Control Problems (FOCPs) formulated in Agrawal (2004) where a Fractional Derivative (FD) is defined in the Riemann-Liouville sense. In this scheme, the entire time domain is divided into several sub- domains, and a fractional derivative (FDs) at a time node point is approx- imated using a modified Grunwald-Letnikov approach. For the first order derivative, the proposed modified Grunwald-Letnikov definition leads to a central difference scheme. When the approximations are substituted into the Fractional Optimal Control (FCO) equations, it leads to a set of alge- braic equations which are solved using a direct numerical technique. Two examples, one time-invariant and the other time-variant, are considered to study the performance of the numerical scheme. Results show that 1) as the order of the derivative approaches an integer value, these formulations lead to solutions for integer order system, and 2) as the sizes of the sub- domains are reduced, the solutions converge. It is hoped that the present scheme would lead to stable numerical methods for fractional differential equations and optimal control problems.
181 citations
TL;DR: In this paper, a sliding mode control scheme for a three-dimensional overhead crane is proposed, which guarantees the asymptotic stability of the closed-loop system, has two objectives: position regulation and anti-swing control.
Abstract: This paper deals with the sliding mode control of a three-dimensional overhead crane. The model of the crane consists of five highly nonlinear second-order ordinary differential equations. The crane is an underactuated system, which makes the design of its controllers intricate. A sliding mode control scheme is proposed for the crane. This scheme, which guarantees the asymptotic stability of the closed-loop system, has two objectives: position regulation and anti-swing control. The performance of the closed-loop system is simulated using MATLAB. The simulation results indicate that the proposed control scheme works well. In addition, the robustness of the controller with respect to uncertainties in the crane parameters is investigated through simulations. It is found that the controller is robust to changes in the parameters. Moreover, since some of the states of the system are not measurable, a Luenberger-type observer is proposed. Simulation of the controlled system using the observer-based sliding mode controller produced good results.
171 citations
TL;DR: In this article, the servo control design problem for constraint-following is thoroughly discussed in an algebraic setting in which a second order constraint is adopted, and the complete solution to this problem is provided in analytical form.
Abstract: A mechanical system is required to obey a set of constraints. The tools to accomplish this performance requirement are a set of servo controls1 that is, the servo controls are to generate the appropriate constraint force. In this article, the servo control design problem for constraint-following is thoroughly discussed. The problem is formulated as an algebraic setting in which a second order constraint is adopted. The control is a solution to the problem, whose projection to a subspace is used to ensure conformation to the constraint. The complete solution to this problem is provided in analytical form. It is shown that the environmentally constrained system simply adopts the minimum form of the complete solution. The setting presented here helps to broaden the scope of traditional Lagrangian mechanics.
108 citations
TL;DR: In this paper, the analysis of fractional order Van der Pol systems is studied in the literature, based on the existing theorems on the stability of incommensurate fractional-order systems.
Abstract: This paper is devoted to the analysis of fractional order Van der Pol system studied in the literature. Based on the existing theorems on the stability of incommensurate fractional order systems, w...
98 citations
TL;DR: In this article, the authors prove a necessary optimality condition for isoperimetric problems under nabbla-differentiable curves and apply it to a dynamic optimization problem from economics.
Abstract: We prove a necessary optimality condition for isoperimetric problems under nabla-differentiable curves. As a consequence, the recent results of Caputo (2008), that put together seemingly dissimilar optimal control problems in economics and physics, are extended to a generic time scale. We end with an illustrative example of the application of our main result to a dynamic optimization problem from economics.
95 citations
TL;DR: In this paper, the effectiveness of the neuro-fuzzy model in predicting the health condition of bearings was verified using simulation and an experiment with results showing that the model is reliable and robust forecasting tool, and more accurate than a radial basis function network.
Abstract: A reliable prognostic model is very useful for industries to forecast equipment behaviors. The aim of this research is to verify the effectiveness of the neuro-fuzzy model in predicting the health condition of bearings. Simulation and an experiment have been carried out to verify the model, with results showing that the neuro-fuzzy model is a reliable and robust forecasting tool, and more accurate than a radial basis function network. In the experiment, vibration data collected from the equipment is used to predict the future condition.
92 citations
TL;DR: In this paper, the authors investigated the convenience of tuned mass dampers for the reduction of the gust response for the case of the towers of suspension bridges, and reported on the weak performance to seismic excitation.
Abstract: The convenience of Tuned Mass Dampers for the reduction of the gust response is investigated for the case of the towers of suspension bridges. For this special typology the design must pursue effectiveness, robustness and redundancy performance. Suitable solutions are multi-device provisions (MTMD), with distributed mass, frequency and damping. Increasing the robustness of MTMD against mistuning beyond the optimal configuration produces a loss of efficiency: as a result the final choice is determined only at the end of the constructive process. A brief discussion is reported on the weak performance to seismic excitation.
85 citations
TL;DR: In this article, a method for the fault diagnosis of rolling bearing is proposed based upon Hilbert envelope spectrum and support vector machine (SVM) for multi-class classification of bearing vibration signals.
Abstract: Based upon Hilbert envelope spectrum and support vector machine (SVM), a method for the fault diagnosis of rolling bearing is proposed in this paper. Targeting the modulation characteristics of rolling bearing fault vibration signals, the Hilbert transform based envelope spectrum analysis is used to extract fault bearing features. In the envelope spectrum, character frequencies are quite clear and can be used as a reliable source of information for bearing diagnosis. Basic SVM is originally designed for two-class classification problem, while bearing fault diagnosis is multi-class case. A new bearing fault diagnosis system based on “one to others” SVM algorithm is presented to solve the multi-class recognition problems. Practical vibration signals measured from rolling bearings with ball fault, inner race fault and outer race fault are analyzed by the proposed method. The results show that the proposed method provides accurate diagnosis and good diagnostic resolution.
74 citations
TL;DR: In this article, the authors used two different approaches for modeling and control of the mechanical and electrical parts of the suspension systems with the magnetorheological (MR) damper.
Abstract: This paper presents the control strategies of nonlinear vehicle suspension using a magnetorheological (MR) damper. We used two different approaches for modeling and control of the mechanical and electrical parts of the suspension systems with the MR damper. First, we have formulated and resolved the control problem in order to design the linear feedback dumping force controller for a nonlinear suspension system. Then the values of the control dumping force functions were transformed into electrical control signals by the application of a fuzzy logic control method. The numerical simulations were provided in order to show the effectiveness of this method for the semi-active control of the quarter-car suspension.
69 citations
TL;DR: In this paper, the shape memory alloy (SMA) wire actuators are used for vibration and position control of a flexible beam structure by adopting Shape Memory Alloy actuators, and a sliding mode controller is formulated for vibration control with relatively large tip displacement.
Abstract: This paper presents vibration and position control of a flexible beam structure by adopting shape memory alloy (SMA) wire actuators. The governing equation of motion of the proposed flexible structure is obtained via Hamilton's principle. The dynamic characteristics of the SMA wire actuator are experimentally identified and incorporated with the governing equation to furnish a control system model in the state space. Subsequently, a sliding mode controller which has inherent robustness to external disturbances and parameter uncertainties is formulated. The controller is then empirically realized for vibration control with relatively large tip displacement. In addition, tip position tracking control to follow desired trajectories with low-frequency sine and square waves is undertaken. Control performances such as tracking error are evaluated through both computer simulation and experimental investigation in time domain.
50 citations
TL;DR: A physical model in the form of a 22-degrees-of-freedom half light rail transport vehicle and differential equations created for analyzing vibrations are created and a fuzzy logic controller is used to actively control vibrations in the simulation environment.
Abstract: A high standard service must be provided in rail transportation for passenger safety and comfort. With this need in mind, data are collected on vibration problems in rail systems and control. In this study, a rail vehicle system in use in Istanbul traffic is studied and a physical model in the form of a 22-degrees-of-freedom half light rail transport vehicle and differential equations created for analyzing vibrations. A computer simulation is also been carried out. In the simulation, real parameters for the modeled vehicle are employed. In an effort to minimize displacement and acceleration of the vibrations obtained in the end of simulations based on time and frequency domains, a fuzzy logic controller is used to actively control vibrations in the simulation environment.
TL;DR: In this article, a shape memory alloy (SMA) damper was applied to control cable vibration under external excitations, motion equations and corresponding state equation of the system made up of SMA dampers and a cable were described based on Hamilton Principle, and the system's optimization problems based on the linear quadratic regulator (LQR) active control algorithm were investigated to obtain the optimum cable vibration control effects and control forces.
Abstract: In order to apply shape memory alloy (SMA) damper for effective control of cable vibration under external excitations, motion equations and corresponding state equation of the system made up of SMA dampers and a cable are described based on Hamilton Principle, and the system's optimization problems based on the linear quadratic regulator (LQR) active control algorithm are investigated to obtain the optimum cable vibration control effects and control forces. According to the equivalency between SMA damper optimum passive control effects and LQR active control effects, the optimal design principle and methods of SMA damper for cable vibration control are proposed. Utilizing the above optimal methods, an SMA damper is designed to control vibration of a practical cable under white noise excitations, and its control effects are compared with the LQR active control effects by numerical simulation. Results show that the cable vibration responses under both LQR active control and SMA damper optimum control are obviously less than those without control, and SMA damper optimum control effects are approached to the LQR active control effects. This may indicate the effectiveness of the supposed SMA damper optimum design methods for cable vibration control.
TL;DR: In this paper, a Bernoulli-Euler beam fixed on a moving cart is analyzed for high performance piezoelectric vibration absorber, which is mounted on the ball-screw mechanism system.
Abstract: The main goal of this research is to develop a novel approach for achieving a high performance piezoelectric vibration absorber. Motion and control of a Bernoulli-Euler beam fixed on a moving cart will be analyzed in this study. The moving cart is mounted on the ball-screw mechanism system. Dynamic formulation for control purposes is first investigated for such a beam-cart system in this research. The controller has two separate feedback loops for positioning and damping, and the vibration suppression controller is independent of linear motion stage positioning control. The decomposed parallel fuzzy control with adaptive neuro-fuzzy concept has also been proposed for this research. An experimental device was constructed, constituted of a flexible cantilever aluminum beam type structure with piezoelectric patches symmetrically bonded on both sides to provide structural bending. Strip-bender type piezoelectric patches were attached to the surface of the beam to serve as actuators and sensor, respectively. Experimental validation for such a structure demonstrates the effectiveness of the proposed controller. The results of this study can be feasible to various mechanical systems, such as high tower cranes, ladder cars or overhead cranes.
TL;DR: In this paper, an experimental design method for noise and vibration analysis of two car engines by feedforward and radial basis neural networks is presented, and two types of car engines are experimentally analyzed by using intelligent data acquisition card with software.
Abstract: An experimental design method for noise and vibration analysis of two car engines by feedforward and radial basis neural networks is presented. Two types of car engines are experimentally analyzed by using intelligent data acquisition card with software. Measured vibration and noise parameters of two car engines are used as desired values of the neural networks. The effectiveness of using Radial Basis Neural Network (RBNN) with backpropagation algorithm is demonstrated for predicting the vibrations and noises of two car engines. The robustness of the proposed RBNN predictor to parameters of vibration and noise as well measurement disturbances is investigated. The result of experiments and simulation show that the proposed RBNN is able to adapt effectively under disturbances.
TL;DR: In this article, a non-ideal mechanical system with clearance is considered, where the connecting force between the motor and the fixed part of the system is discontinuous but linear.
Abstract: In this paper a non-ideal mechanical system with clearance is considered. The mechanical model of the system is an oscillator connected with an unbalanced motor. Due to the existence of clearance the connecting force between motor and the fixed part of the system is discontinuous but linear. The mathematical model of the system is represented by two coupled second-order differential equations. The transient and steady-state motion and also the stability of the system are analyzed. The Sommerfeld effect is detected. For certain values of the system parameters the motion is chaotic. This is caused by the period doubling bifurcation. The existence of chaos is proved with maximal Lyapunov exponent. A new chaos control method based on the known energy analysis is introduced and the chaotic motion is transformed into a periodic one.
TL;DR: In the presence of link flexibility, the problem becomes more difficult and difficult and cri... as discussed by the authors, the problem of robot motion planning between two given configurations in the time domain has a great impact on robotic applications.
Abstract: Robot motion planning between two given configurations in the time domain has a great impact on robotic applications. In the presence of link flexibility, the problem becomes more difficult and cri...
TL;DR: Based on the theory of rigid body dynamics, the model of the horizontal vibratio... is presented in this article, where the robust controller design of horizontal vibrations for high-speed elevators is presented.
Abstract: Modeling and robust controller design of horizontal vibrations for high-speed elevators are presented in this paper. Based on the theory of rigid body dynamics, the model of the horizontal vibratio...
TL;DR: In this article, an active feedback method asymptotically learns the unbalance-induced disturbance forces from the resulting disturbance estimates, and then identifies the unknown unbalance parameters of a rotor.
Abstract: This note presents a new method for identifying the unknown unbalance parameters of a rotor. The active feedback method asymptotically learns the unbalance-induced disturbance forces. From the resulting disturbance estimates, we show how to identify the unbalance parameters. Simulation results illustrate the proposed identification method.
TL;DR: In this paper, a sliding mode flow controller for connection-oriented, multi-source, single-bottleneck communication networks is proposed, which is designed in such a way that the closed-loop system stability and finite time error convergence are ensured.
Abstract: In this paper, we propose a sliding mode flow controller for connection-oriented, multi-source, single-bottleneck communication networks. For that purpose, we model the networks as discrete time systems with the available bandwidth acting as the disturbance. The proposed control algorithm is designed in such a way that the closed-loop system stability and finite time error convergence are ensured. Moreover, we demonstrate that the proposed controller guarantees no bottleneck link buffer overflow and full utilization of its available bandwidth. Furthermore, transmission rates generated by the controller are always bounded and nonnegative.
TL;DR: In this paper, a miniature modal shaker was installed between the cabin floor and the seat bottom as an adaptive mount that provided the actuation authority to reduce the vertical vibration transmitted to the aircrew helmet in order to decrease aircrew neck and spine injuries.
Abstract: Helicopter aircrew are exposed to high levels of vibration and noise during flight. This paper presents the investigation of adaptive seat mount approaches to reducing vibration on the helicopter seat. A flight test on a helicopter with typical pilot configurations showed that the vibration spectra on the pilot’s helmet not only included the dominant N/rev harmonic peaks of the rotor speed, but also consisted of a low-frequency resonant peak in the frequency range of human abdominal and spine resonant frequencies. Long-term exposure to this vibration may lead to occupational health issues such as damage to the pilot’s spine and neck. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew. As a proof-of-concept demonstration, a miniature modal shaker was installed between the cabin floor and the seat bottom as an adaptive mount that provided the actuation authority. The objective was to reduce the vertical vibration transmitted to the aircrew helmet in order to decrease aircrew neck and spine injuries that are caused by the transmitted vibration. Extensive closed-loop control tests have been conducted on a full-scale helicopter seat and a mannequin with varying physical properties. A 10,000 lb(f) mechanical shaker was used to provide representative helicopter vibration profiles to the seat. Significant vibration reductions on the N/rev vibration peaks were achieved1 the low-frequency resonant peak was also suppressed simultaneously.
TL;DR: In this paper, a simplified simulation model of electrical rotating machinery and an experimental test rig for applying the Vold-Kalman filter order tracking technique (VKF-OT) are presented.
Abstract: This paper presents a simplified simulation model of electrical rotating machinery and an experimental test rig for applying the Vold-Kalman filter order tracking technique (VKF-OT). The effectiveness and advantages of VKF-OT for condition monitoring are demonstrated on both the simulation model and the experimental test rig through time domain analysis, using crest factor and kurtosis. The choice of the Vold-Kalman filter bandwidth is considered in the context of the simulation model, based on two different damping ratios. Several observations are made regarding the choice of Vold-Kalman filter bandwidth for the different damping ratios. Three different filter bandwidths are subsequently considered in a study of the experimental data, to confirm the conclusions made during the simulation study.
TL;DR: In this paper, an extension of an existing procedure for evaluating the waveguides and the dispersion curves of a laminate made up of thin orthotropic composite plates arbitrarily oriented is presented.
Abstract: This work presents the extension of an existing procedure for evaluating the waveguides and the dispersion curves of a laminate made up of thin orthotropic composite plates arbitrarily oriented. The adopted approach is based on one-dimensional finite-element mesh throughout the thickness. Stiffness and mass matrices available in the literature for isotropic material are reported in full expanded form for the selected problem. The aim of the work is the development of a tool for the simulation of the most common composite materials. The knowledge of the wave characteristics in a plate allows correct sizing of the numerical mesh for the frequency-dependent analysis. The development of new stiffness matrices and the analysis for different heading angles are detailed to take into account the general anisotropic nature of the composite. The procedure concerns a standard polynomial eigenvalue problem in the wavenumber variable and is focused on the evaluation of the dispersion curves for all the propagating waves within the materials. A comparison with an analytical approach is also shown in the results using the classical laminate plate theory (CLPT). However, limits of CLPT are outlined and spectral finite element method can be successfully used to overcome such limitations.
TL;DR: In this paper, the applicability of non-linear state observation to cable dynamics is explored, and a non-collocated feedback control strategy based on transversal actuation is considered, in which the control algorithm is based on the estimated state variables.
Abstract: We explore the applicability of non-linear state observation to cable dynamics. The aim is to capture from the minimal number of measurements a larger description of the state to be employed in active or semi-active control policies. To this end, a non-linear state observer is designed analytically, in the space of modal amplitudes, following relevant literature results. The main theory of non-linear state observation is preliminary reviewed and the applicability to the dynamics of structural cables is discussed, including asymptotic stability and minimal number of measurements. Next a sample non-resonant cable is considered and numerical simulations are carried out in order to test the observation error stability under different conditions. A non-collocated feedback control strategy, based on transversal actuation, is finally considered, in which the control algorithm is based on the estimated state variables. The with-observer control solution is compared with the ideal case in which the entire state of...
TL;DR: In this paper, a continuous monodimensional model of a damaged cable is used for this purpose, and a damage identification problem is formulated by defining an objective error function between the measured and the model frequencies, to be minimized in the space of the damage parameters.
Abstract: Structural cables in cable-stayed systems are subject to potential damage, mainly due to fatigue phenomena and galvanic corrosion. The paper analyzes how the dynamical b ehavior of cables is affected by diffuse damage, and investigates whether the damage can be identified through information selected from the dynamical response. A continuous monodimensional model of a damaged cable is used for this purpose. Damage is described as a reduction of the cable cross section, and defined in terms of its intensity, extent and position. The major effects of these different damage parameters on the cable static response and spec- tral properties are evidenced and discussed to verify the observability of the damage. The frequencies of the dominant transversal motion of the cable are chosen as damage indicators, since they are sufficiently sensitive to the damage intensity and extent, while the damage position requires additional information. The damage identification problem is formulated by defining an objective error function between the measured and the model frequencies, to be minimized in the space of the damage parameters. Pseudo-experimental data are ini- tially used to test the effectiveness and resolution of the procedure. The results confirm the uniqueness of the problem solution and its correctness. The robustness of the solution is discussed while considering the pres- ence of random errors of increasing amplitude. The procedure is also positively verified with experimental measures from a prototype model of an artificially damaged spiral strand.
TL;DR: In this article, a combination of backstepping and integrator forwarding is used to control an electro-hydraulic active suspension, which can be classified among interlaced systems.
Abstract: Passengers' comfort in long road trips is of crucial importance1 as a result, active suspension control became a vital subject in recent researches. This paper studies the control of an electrohydraulic active suspension, based on a combination of backstepping and integrator forwarding. Our goal is to control and reduce the car's vertical motion and keep it to zero. The active suspension model is highly nonlinear and nondifferentiable due to the hydraulic components, especially the servovalve and the hydraulic actuator whose chambers' volume varies during extension and retraction. Therefore, a powerful control strategy is required. In such cases, Lyapunov-based control strategies are the most suitable for offering a lot of maneuverability in building an analytical control signal. The mathematical model of an electrohydraulic active suspension can be classified among interlaced systems. This means that the state space model is a sequence of feedback and feedforward equations. Therefore, interlaced backstep...
TL;DR: In this article, a multimodal H∞ controller for piezoelectric actuated plates designed to simultaneously suppress vibrational components of the first two modes was developed for a reduced structural model.
Abstract: This paper presents the development of a multimodal H∞controller for piezoelectric actuated plates designed to simultaneously suppress vibrational components of the first two modes. The controller is developed for a reduced structural model. The closed-loop control scheme is subject to both uncertainties due to control and observation spillover in the unmodeled residual modes and to parametric errors in the structural model. The closed-loop stability and performance robustness is analyzed using μ-analysis, and numerical investigations indicate that the controller tolerates uncertainties of significant size.
TL;DR: In this article, a crack localization algorithm based on a mathematical model describing the lateral vibration of a rotating cracked Timoshenko beam is proposed, where the Lagrange equation and the assumed mode method are used to derive the model.
Abstract: In this paper a new crack localization algorithm based on a mathematical model describing the lateral vibration of a rotating cracked Timoshenko beam is proposed. The Lagrange equation and the assumed mode method are used to derive the model. The localization algorithm utilizes the variation in a single natural frequency of the beam versus a few rotor speed values to detect and localize a crack. The algorithm has different means of checking/reconfirming its crack estimate. This may be used to improve the accuracy of the decision. Also, the effect of rotational speed and crack location on the system's dynamical characteristics is investigated using the derived mathematical model. The results are compared with those obtained from a three-dimensional finite-element analysis. Good agreement is observed between the two sets of results. Finally, the reliability of the identification algorithm is established using the data obtained from the finite- element analysis.
TL;DR: In this article, a numerical algorithm to compute and compare the transmitted force reduction produced by these two types of designed elements is proposed in order to provide an important basis for the design of nonlinear materials and nonlinear engineering systems.
Abstract: The transmitted force around the resonant region of a system can be significantly reduced by introducing designed nonlinearities into the system. The basic choice of the nonlinearity can be either a nonlinear spring element or a nonlinear damping element. A numerical algorithm to compute and compare the transmitted force reduction produced by these two types of designed elements is proposed in this study. Analytical results are used to demonstrate the procedure. The numerical results indicate that the designed nonlinear damping element produces low levels of higher-order harmonics and no bifurcations in the system output response. In contrast, the nonlinear spring-based designs induce significant levels of harmonics in the transmitted force and can produce bifurcation behaviour. The conclusions provide an important basis for the design of nonlinear materials and nonlinear engineering systems.
TL;DR: In this paper, the first passage failure of a strongly nonlinear stochastic system with fractional derivative damping under white noise excitations using the generalized harmonic function is studied.
Abstract: The first passage failure of single-degree-of-freedom (SDOF) strongly nonlinear stochastic system with fractional derivative damping is studied. The stochastic averaging method for SDOF strongly nonlinear stochastic system with fractional derivative damping under white noise excitations using the generalized harmonic function is introduced. The averaged Ito equation for Hamiltonian is obtained by using the stochastic averaging method. Then, a backward Kolmogorov equation governing the conditional reliability function and a Pontryagin equation governing the mean of the first passage time are established. The conditional reliability function, and the conditional probability density and mean first passage time are obtained from solving these equations together with suitable initial condition and boundary conditions. Finally, two examples are worked out in detail and the solutions are confirmed by using Monte Carlo simulation of original systems.
TL;DR: In this paper, the coupled governing equations of motion for general curved beams with the attached tuned mass damper including the effects of curved beam axis extensibility, shear deformation and r...
Abstract: In this paper the coupled governing equations of motion for general curved beams with the attached tuned mass damper including the effects of curved beam axis extensibility, shear deformation and r...