Showing papers in "Journal of Low Frequency Noise Vibration and Active Control in 2013"

Fuzzy Control for Semi-Active Vehicle Suspension

Abstract: In this paper semi-active control of the suspension of an all-terrain vehicle is considered. A seven degree of freedom suspension model is presented first. A fuzzy approach for controller synthesis is then proposed. Expert knowledge is stored in the form of IF-THEN rules. The Takagi-Sugeno inference system is employed, with triangle membership functions. The fuzzy system output is the damper coefficient. In contrary to many other control algorithms, the presented fuzzy algorithm does not require inverse modelling of the magnetorheological damper. Instead, some scaling parameters are set. They can be chosen experimentally, or a bio-inspired strategy can be applied. The fuzzy control is then compared with the Skyhook control in simulations, in terms of road holding and driving comfort indicators. Obtained results are similar. However, lack of necessity to use an MR inverse model allows the fuzzy system to provide successful performance in case of different operating conditions, what is an important benefit.

Optimal Control of Slow-Active Vehicle Suspension — Results of Experimental Data

Abstract: Laboratory investigations of an active vehicle suspension of an in-series structure of the slow-active type are presented in this paper. The multidimensional model is reduced to a case representing quarter car suspension. Control laws for active vibration reduction systems are usually determined based upon linear models of objects. Active suspensions are characterised by nonlinearity, connected most often with actuating systems and their energetic restrictions. This causes divergences between theoretical quality factors and those determined experimentally. The second essential problem is finding a compromise between opposed quality factors (for example, minimum power requirement and high efficiency of vibration reduction).Thanks to the use of the proper control law in the active vibration reduction system of vehicle suspension, the goal of ensuring a high level of ride comfort, good vehicle handling and incessant contact of the wheels with the road surface with a minimum power requirement may be attained....

Adaptive Sliding Mode Vibration Control of a Nonlinear Smart Beam: A Comparison with Self-Tuning Ziegler-Nichols PID Controller

Abstract: This paper investigates the vibration control of geometrically nonlinear beam with Macro Fiber Composite (MFC) actuators using two different adaptive control algorithms. A complete mathematical modeling is presented in order to find the dynamic equation of motion. Then, a robust adaptive fuzzy control algorithm for controlling the proposed mechanical structure is introduced. This controller includes a fuzzy scheme and a robust controller. Based on sliding mode controller a fuzzy system is introduced to mimic an ideal controller. The robust controller is designed based on compensation of the difference between the fuzzy controller and the ideal controller. The parameters of the fuzzy system and uncertainty bound of the robust controller are adjusted adaptively. The adaptive laws are designed based on the Lyapunov stability theorem to reach the stability of the closed-loop system. Meanwhile, for comparison purposes the presented controller is compared with self tuning Ziegler-Nichols PID controller for both...

Bench Tests of Slow and Full Active Suspensions in Terms of Energy Consumption

Abstract: This paper is focused on the problem of active suspensions of wheeled vehicles with electro-hydraulic actuators. Two dynamic structures first with actuator connected with spring in series and second in parallel - called slow active and full active respectively - were considered. The considerations described in the paper concern physical quarter-vehicle models of suspensions. These models were constructed and installed on a rig for dynamic tests of structures. A laboratory rig enables the simulation of real conditions by disturbing investigated suspension by kinematic excitation. Research was carried out for various algorithms controlling the actuator of the active unit. For evaluation of laboratory research results, comparisons were proposed of frequency response functions and of time curves of instantaneous power taken by the active system from supply, obtained at the same excitation signals. Quantitative aggregated indicators in the form of an averaged coefficient of vibration transmissibility and power...

Application of an SMA Spring for Vibration Screen Control

Abstract: Use of springs made of an alloy with shape memory (SMA) to shape the dynamic characteristics of a resonance vibration screen is proposed in this paper. These springs change spring constant as a result of temperature changes. Thus it is possible to change their resonance frequency in real time. In the paper a mathematical model of a controlled SMA spring was formulated and its parameters were identified. In the model both the effect of spring coefficient changes and damping changes depending upon alloy temperature and spring vibration frequency were taken into consideration. Experimental investigations of the examined spring and screen physical model were carried out and selected characteristics were also included. The investigations were carried out at the Dynamics and Control of Structures Laboratory of AGH University of Science and Technology. The control law was formulated. Simulation investigations of the mathematical vibration screen model in both open and closed loop systems were made. It was shown ...

Roll Movement Control of a Spray Boom Structure using Active Force Control with Artificial Neural Network Strategy

Abstract: Currently, most of modern sprayers are equipped with suspensions for improving the uniformity of spray application in the field. Therefore, this paper represents the possibility of applying active force control (AFC) technique for the control of a spray boom structure undesired roll movement through a simulation analysis. The dynamic model of the spray boom was firstly defined and an AFC-based scheme controller was designed and simulated in MATLAB environment. Artificial neural network (ANN) is incorporated into the AFC scheme to tune the proportional-derivative (PD) controller gains andcompute the spray boom estimated mass moment of inertia. The training of both ANN with multi layer feed forward structure was done using Levenberg-Marquardt (LM) learning algorithm. To evaluate the AFC-ANN control system robustness, various types of disturbances and farmland terrain profileshave been used to excite the spray boom. The results of the study demonstrated that the AFC-based method offers a simple and effective...

Low Frequency Damage Analysis of Electric Pylon Model by Fuzzy Logic Application

Abstract: The paper presents a proposition of a new method for calculating the damage degree of electric pylon model by fuzzy logic application. Damage changes in constructions manifest themselves in small but detectable variations of frequency. The change of the speed of wave propagation, which is associated with the change of the natural frequency in the system, is caused by the deformation of the examined material. This phenomenon can be used for an indirect analysis of the construction damage. The main aim of the article is presentation of the results of the vibrations analyse of the electric pylons. In the preliminary tests the research was conducted on the simulation data of the electric pylon of power grid. Eight construction elements of pylon in different positions were chosen to simulate the damage by decreasing step by step the Young's modulus. The simulation data was obtained on the basis of the stiffness matrix updated in conjunction with the Finite Element Method. The preliminary research presented in ...

Construction of a Parametrized Tracked Vehicle Model and its Simulation in MSC.ADAMS Program

Abstract: The paper summarizes the methods of a tracked vehicles model construction in MSC.ADAMS program. Advantages and faults of these methods are described here. Finally, the authors describe one chosen method with exact elements geometry of the chosen real suspension parts. Basis on this method, a construction of the tracked vehicle model is described. Parts of this model are parameterized and can be fluently changed with usage of a dedicated user interface. Next, a part of the tracked vehicle simulation results is presented.

Vibration Surveillance During Milling Flexible Details with the Use of Active Optimal Control

Abstract: The main goal of modern machining operations is to achieve increasingly better performance. High Speed Machining and/or High Performance Cutting, despite a lot of advantages, have also some drawbacks, for example, a possibility of losing stability and development of self-excited chatter vibration. This paper presents an approach of vibration surveillance during high speed milling with a use of active optimal control. Non-stationary model of the milling process is described with the use of convention of the discrete hybrid system, and the problem of optimal control at energy performance index is defined and resolved. Numerous computer simulations disclosed efficiency of the surveillance by the active optimal control of flexible workpiece vibration. The performed real experiments of the milling process support the meaning of the method of vibration surveillance.

Vertical and Fore-Aft Seat-to-Head Transmissibility Response to Vertical Whole Body Vibration: Gender and Anthropometric Effects

Abstract: In this study, the biodynamic responses to vertical vibration are investigated in terms of seat-to-head vibration transmissibility (STHT) to study the effects of gender and eleven different anthropometric parameters on the STHT responses in the vertical and fore-aft directions. The STHT response of 31 male and 27 female human subjects were measured under three levels of vertical vibration (0.25, 0.50 and 0.75 m/s2 rms acceleration) in the 0.50 to 20 Hz range, while seated without a back support and against a vertical back support with hands on a steering wheel. The results showed that the vertical and fore-aft STHT responses of the two genders were distinctly different. The primary resonance frequency of the male subjects was higher than the female subjects, while the peak magnitudes were comparable. The male subjects showed relatively greater softening effect, i.e. decrease in the primary resonance frequency with increase in excitation magnitude, as compared to the female subjects, irrespective of the si...

Vibratory sensation induced by low-frequency noise: The threshold for "vibration perceived in the head" in normal-hearing subjects

Abstract: Our previous study, in which we measured the threshold levels for vibratory sensation induced by low-frequency noise under the condition that the subjects were allowed to perceive vibration in any part of the body, showed that the head was very sensitive to the vibratory sensation. In the present study, in which the head was designated as the body part that would perceive the vibration, we measured the threshold levels for experiencing “vibration perceived in the head” within the 16- to 80-Hz frequency range. The threshold levels for “vibration perceived in the head” were found to be very similar to the threshold levels measured in our previous study, which indicated the superior sensitivity of the head to vibratory sensation induced by low-frequency noise. A gap appeared around 40-50 Hz in the threshold level contour for “vibration perceived in the head”. In addition, the threshold levels for “vibration perceived in the head” increased when a subject wore an active noise cancelling earmuff. These results suggested the possibility that experiencing “vibration perceived in the head” was related to the pressure change in the ear.

Ant Colony Optimization for Controller and Sensor-Actuator Location in Active Vibration Control

Abstract: Developing light weight yet stronger and more flexible panels in aircraft structure to with stand from failure due to vibration has been the interest of many researchers nowadays. Piezoelectric material has been the popular choice to attenuate vibration actively and numerous techniques of optimal control and actuator placement have been proposed. This paper discusseson active vibration control of a simply supported thin plate excited and actuated by piezoelectric patches. Mathematical model of the simply supported plate with piezoelectric patches is derived using Euler-Bernoulli model. The main focus is to find the optimal location of the collocated sensor-actuatorand controller gains using a swarm intelligent algorithm called Ant Colony Optimization (ACO) which later verified with Genetic Algorithm (GA). A simply supported plate is taken as a benchmark model to perform simulation study.

Traffic noise prediction and the influence of vehicle Horn Noise

Abstract: A study was conducted to propose statistical models in order to predict equivalent sound pressure level (LAeq (1h)) and maximum sound pressure level (LAFmax (1h)) due to road traffic. Variables including traffic flow, vehicles' speed, relative humidity, the length and width of the segments of the roads, the average height of the buildings located around the road and the slope of the segments of roads were considered. Also, the vehicle horn noise as a predictor variable was included in the models. The results reveal that LAFmax (1h) values are considerably higher than LAeq (1h) values. It is concluded that the vehicle horn noise may be responsible for the considerable difference between LAeq (1h) values and LAFmax (1h) values. Hence, to study traffic noise pollution the vehicle horn noise must be taken into consideration.

A Review of Prediction Methods for the Transient Vibration and Sound Radiation of Plates

Abstract: Transient noise is a typical real-life noise problem. In order to develop efficient methods of dealing with it, the generating and transmitting mechanisms of transient noise radiating from a vibrating structure have been widely studied. The analytical methods used differ according to the properties of the excitation, structure, and acoustic environment. Focusing on plate-like structures, this paper provides an overview of commonly-used approaches to the analysis of structural transient vibration and sound radiation (TVSR). A general process for solving this type of problem is presented, together with suggestions for future work in this field.

Active Vibration Control of Moving Web With Varying Density

Abstract: Nowadays more and more materials can be manufactured or stored in continuous web form. The vibration of the moving web limits the productivity and quality of the web materials. The active vibration control of the moving web with varying density is considered in this paper. Finite difference method is used to discretize the dynamic equations of the moving web with varying density and derive the state equation of transverse vibration control system for the moving web with varying density. The simulation of the response and decay process of transverse vibration for the moving web with varying density after the implementation of suboptimal control is performed by numerical calculation.

Self-Excited Acoustical System for Stress Measurement in Mass Rocks

Abstract: The paper is devoted to theoretical end experimental studies of the low-frequency Self-excited Acoustical System (SAS), which allows monitoring stress changes in various elastic media including metals, concrete and mass rocks. The main principle of the SAS system is using a vibration exciter and vibration receiver placed on a sample with a positive feedback, which causes the excitation of the system. Stress changes manifest themselves in small but detectable variations of resonance frequency which can be used to indirectly measure stress changes in the material.In the paper the considerations concerning working frequency of SAS were performed. It was suggested that in the case of stress variation in mass rock monitoring, the low frequency (even infrasound) band should be selected, in contrast to the stress monitoring in columns of marble or concrete, where frequencies from an acoustic band should be used. Computer simulations conducted in the MATLAB-Simulink environment were based on the research performe...

Modal Sensitivity and Selectivity of Small, Rectangle-Shaped Piezoelectric Transducers used as Sensors and Actuators in Active Vibroacoustic Control Systems

Abstract: The paper focuses on some issues regarding the utilization of small rectangle-shaped piezoelectric transducers as both sensors and actuators in active vibration and vibroacoustic control systems of beam, plate and panelled structures with arbitrary (non-homogeneous) boundary conditions. A new form of description of a simple proportional active control system with multiple independent feedback loops is proposed. The modal sensitivity functions of sensors and the modal selectivity functions of actuators are introduced to describe their ability for sensing and exciting specific structural modes of the structures. Basing on the assumed form of cost function and the derived equations of control system the influence of the modal characteristics of transducers on the stability of the system and on the performance of the active control is analyzed. The results of analytical solutions and numerical simulations are compared with the results of the experiments carried out on various beam and plate structures made up...

Optimal Control of Nonlinear Resonances for Vehicle Suspension using Linear and Nonlinear Control

Abstract: The dynamic equations of the strongly nonlinear vibration of vehicle suspension with linear and nonlinear feedback controllers are developed. The strongly nonlinear vibration is transformed into the weakly nonlinear vibration by the nonlinear controller. The forced vibration of vehicle suspension is studied by the method of multiple scales. The regions of feedback gains obtained from the stability conditions of eigenvalue equation quantitatively are presented. Taking attenuation ratio and energy function as the objective functions, the control parameters of velocity and displacement are calculated by the minimum optimal method. Illustrative examples are given to show the effectiveness of vibration control.

The Analysis of a Smart Jeffcott Rotor with Direct Velocity Feedback Control in the Supercritical Range

Abstract: The paper discusses the analysis of the active control of a Jeffcott rotor with the rotational speed in the supercritical range. By the application of collocated sensors and actuators and a suitable control algorithm it has been possible to influence the internal damping of the rotor, which is the origin of self-induced vibrations. By this approach it is possible to increase the range of the stable operation of the rotor. In the paper, a classical analytical two-degree-of-freedom Jeffcott rotor model has been extended to account for the presence of piezoelectric patch sensors and actuators. The applicability of this model has been positively verified through the comparison with the finite element results derived using the Ansys software. Plots have been obtained by both the analytical approach and the finite element method that demonstrate the applicability of velocity feedback to increasing the threshold of instability of the rotor.

Using a high resolution motion capture system to determine 6-DOF whole-body vibration accelerations

Abstract: Comprehensive investigations of the human response to vibration require many markers, accelerometers, and electrodes. The use of multiple measurement systems can result in time intensive subject preparation, large memory requirements for data storage and processing, skin motion artifacts, and subject encumbrance. The purpose of this study was to determine if a VICON™ motion capture system could reliably and accurately measure translational and rotational acceleration levels produced by mobile machines, thereby eliminating the need for accelerometers and potentially minimizing the aforementioned problems. Simulating these vibration exposures in a laboratory, it was found that translational displacements ≥0.1 mm produced absolute peak and RMS average acceleration measurement differences less than 5% between the VICON™ system and an accelerometer. The absolute peak and RMS rotational accelerations determined by the VICON™ system and those produced by a PRSCO™ hexapodrobot differed by 5.44 ± 3.87% and 3.57 ± ...

Balance Platform Vibration Control

Abstract: In the presented paper the problem of balance platform control was considered. The object used during research is the original structure, designed by article authors. The work was divided into three parts: the identification process, control system design and laboratory tests. In the first stage of the identification process a model describing the system was build, using the measurement data recorded on input and output system. The model was built without the knowledge of the mechanisms that occur in the process; only based on the relationship between the measured data. Next the estimation was performed for selection of suitable algorithm, and determination of the parameters of model selected in the previous step. The last step was to verify and to check the results of identification process. By comparing the signals obtained in response to a signal given from the model of a registered object actual output signal, it is possible to visually estimate the accuracy of the identification and designation of th...

Active Control Strategy for Reduction of Vibrations in Mast Exposed to Ground Motions

Abstract: The paper presents an experimental study of active mass damper control strategy based on analysis of energy dissipation The reduced model of telecommunication mast was built in laboratory Using the special laboratory setup the verification of the proposed strategy was carried out for free and forced vibrations Uniaxial and biaxial reduction systems were considered Experiments confirmed that the proposed algorithm is effective The best vibrations reduction was obtained using biaxial reduction system

A Study of Power Transmission Through a Finite Periodic Dual-layer Beam Structure with Transverse Connection

Abstract: A study of the structure-borne sound power transmission through a finite periodic dual-layer beam structure with connection branches was conducted. The results suggest that the power transmitted through the beam structure into the supporting structure depends not only on the characteristics of the source and the supporting structure, but also on the attenuation of the periodic beam elements with the coupling branches and the exciting position of the source. The results also reveal the model under the mono-coupling condition to be similar to that under the multi-coupling condition in the relatively low frequency region. The transmitted power was strongly attenuated in a number of frequency regions, and in a few regions the power was even transmitted into the second layer of the supporting structure. The analysis indicated that this study is useful in understanding the structure-borne sound transmission from the first layer into the second layer of the beam structure.