Active Vibration Control Algorithm Research Articles

Experimental Active Vibration Control in Truss Structures Considering Uncertainties in System Parameters

This paper deals with the study of algorithms for robust active vibration control in flexible structures considering uncertainties in system parameters. It became an area of enormous interest, mainly due to the countless demands of optimal performance in mechanical systems as aircraft, aerospace, and automotive structures. An important and difficult problem for designing active vibration control is to get a representative dynamic model. Generally, this model can be obtained using finite element method (FEM) or an identification method using experimental data. Actuators and sensors may affect the dynamics properties of the structure, for instance, electromechanical coupling of piezoelectric material must be considered in FEM formulation for flexible and lightly damping structure. The nonlinearities and uncertainties involved in these structures make it a difficult task, mainly for complex structures as spatial truss structures. On the other hand, by using an identification method, it is possible to obtain the dynamic model represented through a state space realization considering this coupling. This paper proposes an experimental methodology for vibration control in a 3D truss structure using PZT wafer stacks and a robust control algorithm solved by linear matrix inequalities.

Novel adaptive repetitive algorithm for active vibration control of a variable-speed rotor

The paper describes experimental work that demonstrates the use of repetitive control to attenuate radial vibrations of a variable speed-rotor. The experiments were performed on a rotor test rig having a 3-kg rotor supported by journal bearings. The first bending resonance of the rotor shaft (i.e. the critical speed) was approximately 50 Hz. The objective was to control the radial response at the rotor midpoint by using an actuator located outside the bearing span. A novel aspect of the controller design is that the length of the control output vector of the repetitive controller was updated as a function of the speed of rotation. The speed of rotation determined the required delay time and the repetitive filter length that approximately matches with the delay time. The results obtained were comparable to those achieved in earlier studies with feedforward compensation methods. The best results were achieved when the frequency of rotation enables an integer ratio between disturbance period and sample rate.

Real-time design constraints in implementing active vibration control algorithms

Although computer architectures incorporate fast processing hardware resources, high performance real-time implementation of a complex control algorithm requires an efficient design and software coding of the algorithm so as to exploit special features of the hardware and avoid associated architecture shortcomings. This paper presents an investigation into the analysis and design mechanisms that will lead to reduction in the execution time in implementing real-time control algorithms. The proposed mechanisms are exemplified by means of one algorithm, which demonstrates their applicability to real-time applications. An active vibration control (AVC) algorithm for a flexible beam system simulated using the finite difference (FD) method is considered to demonstrate the effectiveness of the proposed methods. A comparative performance evaluation of the proposed design mechanisms is presented and discussed through a set of experiments.

Design of a Control System using Linear Matrix Inequalities for the Active Vibration Control of a Plate

The study of algorithms for active vibration control in smart structures is an area of interest, mainly due to the demand for better performance of mechanical systems, such as aircraft and aerospace structures. Smart structures, formed using actuators and sensors, can improve the dynamic performance with the application of several kinds of controllers. This article describes the application of a technique based on linear matrix inequalities (LMI) to design an active control system. The positioning of the actuators, the design of a robust state feedback controller and the design of an observer are all achieved using LMI. The following are considered in the controller design: limited actuator input, bounded output (energy) and robustness to parametric uncertainties. Active vibration control of a flat plate is chosen as an application example. The model is identified using experimental data by an eigensystem realization algorithm (ERA) and the placement of the two piezoelectric actuators and single sensor is determined using a finite element model (FEM) and an optimization procedure. A robust controller for active damping is designed using an LMI framework, and a reduced model with observation and control spillover effects is implemented using a computer. The simulation results demonstrate the efficacy of the approach, and show that the control system increases the damping in some of the modes.

Experimental investigation of active vibration control for gear set shaft

In this study, three different active vibration control (AVC) algorithms are implemented and compared in the experimental investigation of gear set shaft vibration control. Apart from feedforward and feedback control system, a hybrid controller is proposed, which is a combination of the adaptive control with filtered-x least mean squares (FXLMS) algorithm and feedback structure with robust synthesis theory for obtaining the fast convergence and good robust performance. The control plant configuration is identified by the frequency domain technique and implemented by using a digital signal processor (DSP). Experiments are carried out to evaluate the vibration attenuation performance of three control systems at gear set shaft. The results of the experiment indicate that the hybrid technique is effective in reducing the vibration and yield the best performance in experimental investigation. The experimental comparison and analysis of the proposed controllers are also described in this paper.

Spacecraft Vibration Suppression Using Variable Structure Output Feedback Control and Smart Materials

A hybrid control scheme for vibration reduction of flexible spacecraft during rotational maneuvers is investigated by using variable structure output feedback control (VSOFC) for attitude control and smart materials for active vibration suppression. The proposed control design process is twofold: design of the attitude controller using VSOFC theory acting on the hub and design of an independent flexible vibration controller acting on the flexible part using piezoceramics as sensors and actuators to actively suppress certain flexible modes. The attitude controller, using only the attitude and angular rate measurement, consists of a linear feedback term and a discontinuous feedback term, which are designed so that the sliding surface exists and is globally reachable. With the presence of this attitude controller, an additional independent flexible control system acting on the flexible parts is designed for further vibration suppression. Using the piezoelectric materials as actuator/sensor, both single-mode vibration suppression and multimode vibration suppression are studied and compared for the different active vibration control algorithms, constant-gain negative velocity feedback (CGNVF) control, positive position feedback (PPF) control, and linear-quadratic Gaussian (LQG) control. Numerical simulations demonstrate that the proposed approach can significantly reduce the vibration of the flexible appendages and further greatly improve the precision during and after the maneuver operations.

Implementation of an active vibration controller for gear-set shaft using [formula omitted]-analysis

A digital signal processor (DSP) implementation of an active vibration controller for reducing periodic vibration in a gear-set shaft is described in this paper. The proposed control algorithms are developed using μ -analysis to obtain robust stability and robust performance in experimental investigation. In experimental work, three different active vibration control algorithms are used, and their characteristics and performances are compared in various experiments. Apart from the traditional adaptive filter and the robust feedback control system, a hybrid controller combining an adaptive controller with a filtered-x least mean squares algorithm and a state feedback theory with a μ -analysis to obtain robust performance and fast convergence is proposed. The control plants are identified by the frequency-domain technique and implemented on a DSP platform. Experiments are carried out to evaluate the attenuation performance and characteristic of three control structures in gear-set shaft vibration. The experimental results indicated that all the three controllers are effective in reducing the gear-set shaft vibration and the hybrid controller demonstrated the best performance in experimental investigation.

중대형 왕복동 기관의 진동제어를 위한 능동형 역기진기 제어 알고리즘 개발

중대형 왕복동 기관의 진동제어를 위한 능동형 역기진기 제어 알고리즘 개발

Vibration Control Using Fuzzy-Logic-Based Active Damping

In this study a general approach is introduced for the design of a robust control law for suppression of structure borne vibration. This control law is based on a passive design in the form of dynamic vibration absorbers. Passive absorbers minimize vibration at a specie c frequency, but their performance is improved by introducing adaptive tuning of the absorber. An adaptive dynamic vibration absorber is tuned to the forcing frequency, using classical methods. The tuning ratio is time varying and adapts itself to variations in the forcing frequency. However, the uniqueness of the approach in this study is that the damping parameter of the absorber is continuously varied by means of a fuzzy-logic control algorithm to provide a lower sound pressure level. The inputs of the fuzzy control law are the displacement and velocity of the main structure. The effectiveness of the control algorithm for active vibration control is demonstrated using MATLAB ® simulations of a single-degree-of-freedom plant. This methodology provides superior performance in the presence of signie cant mistuning compared to a more conventional approach.

Development of a finite element model for the identification of mechanical and piezoelectric properties through gradient optimisation and experimental vibration data

With the increasing use of surface bonded piezoelectric sensors and actuators in laminated structures, rises the need for knowing accurate values for the resulting properties of these structures. The properties obtained through manufacturer data are in most of the cases not enough to predict the structural behaviour and implement efficient control algorithms for active noise and vibration control. To address this issue we propose a discrete finite element model, associated to gradient optimisation and to an inverse method using experimental vibration data to carry out the identification of electromechanical properties in composite plate specimens with surface bonded piezoelectric patches or layers. The properties to be determined are the elastic and piezoelectric constants of the structure’s constituent materials.

Experimental Studies on Adaptive Fuzzy Control of a Smart Structure

The present investigation deals with the application of an Adaptive Fuzzy Control Algorithm for active vibration control of an experimental flexible beam. The two-dimensional model of the experimental cantilever beam, given by an orthogonal tetrahedral space truss, represents a slender cantilever aluminum (7075-T6) beam of rectangular cross-section (1145 × 60 × 1.95 mm3). A variety of transient disturbances are introduced to excite the first four modes of the beam. The resulting transverse displacements are observed by a single sheet (50 × 50 mm2) of piezoceramic material placed at the clamped end of the beam. Active control of the beam is provided by one, two or three identical sheets of piezoceramic material collocated with the sensor. The control moments applied by the piezoceramic actuator are made to emulate the behavior of a discrete dynamic vibration absorber. The virtual absorber is tuned to the fundamental frequency using classical methods and the tuning ratios are time-invariant. However, the uniqueness of this approach is that the damping parameters of the emulated absorber are continuously varied by means of a fuzzy logic control algorithm to provide near minimum-time suppression of vibration. It is demonstrated that application of this methodology allows for its real-time implementation and provides relatively quick settling times in the closed-loop.

Enforcing Structural Connectivity to Update Damped Systems Using Frequency Response

To benefit computational model validation, improve active vibration control algorithms, and aid damage detection for aging structural systems, new approaches are developed to update the analytical system matrices of a damped structure using frequency response. When the difference between the measured frequency response data and the analytical predictions is used and the resulting matrix equations are manipulated, the mass, stiffness, and damping correction matrices can be isolated in turn. When these correction matrices are rearranged into vector forms, the readily available structural connectivity information of the analytical matrices can be enforced, thereby preserving the physical configuration of the system and reducing the size of the least-squares problems that need to be solved. The required solution techniques to perform the model update are introduced, and the numerical issues associated with solving overdetermined and underdetermined least-squares problems are investigated. Heuristic criteria are given for determining the minimum number of frequency-response data points that need to be measured to ensure sufficiently accurate updated system matrices, and numerical experiments are performed to validate the proposed model updating techniques based on using the frequency-response data.

Impact of data dependencies in real-time high performance computing

This paper presents an investigation into the impact of data dependencies in real-time high performance sequential and parallel processing. An adaptive active vibration control algorithm is considered to demonstrate the impact of data dependencies in real-time computing. The algorithm is analysed in detail to explore the inherent data dependencies. To minimize the impact of data dependencies, an investigation into reducing memory access in sequential computing is provided. The impact of data dependencies with various interconnections is also explored and demonstrated in real-time parallel processing through a set of experiments.

Vibration Control of Flexible Manipulators Using Smart Structures

The long reach robots required for space applications necessitate active vibration control algorithms for a better pointing performance. The inherent flexibility of the long and flexible space arms can generate undesirable vibrations, making their end-point controls very difficult, although they provide a large reach volume and payload capabilities. This paper presents a novel technique to control the vibrations of N modes of a flexible link attached to a rigid robot employing an Impedance Control Technique using piezo-ceramic actuators and fiber-optic sensors. A piezo-ceramic actuator model has been developed by considering the moments/forces generated by the piezo-ceramic actuator as nonconservative external forces. Successful simulation and experimental results have been obtained for vibration control of a cantilever beam which is attached to the end effector of the Titan-II robot arm.

A Combination of Fuzzy Logic and Neural Network Algorithms for Active Vibration Control

The construction of a dynamic absorber incorporating active vibration control is described. The absorber is a 2 degree of freedom spring-lumped mass system sliding on a guide pillar, with two internal vibration disturbance sources. Both the main mass and the secondary absorber mass were acted on by direct current (d.c.) servo motors, respectively, to suppress the vibration amplitude. In this paper, a new control approach is proposed by combining fuzzy logic and neural network algorithms to control the multi-input/multi-output (MIMO) system. Firstly, the fuzzy logic controller was designed for controlling the main influence part of the MIMO system. Secondly, the coupling neural network controller was employed to take care of the coupling effect and refine the control performance of the MIMO system. The experimental results show that the control system effectively suppresses the vibration amplitude and with good position tracking accuracy.

CISC, RISC and DSP processors in real-time signal processing and control

This paper presents an investigation into the performance evaluation of advanced complex instruction set computer (CISC) processors, reduced instruction set computer (RISC) processors and digital signal processing (DSP) devices in the real-time implementation of signal processing and control algorithms. The algorithms considered are of varying degree of regularity relative to one another. These include a fast Fourier transform algorithm, a second-order correlation algorithm, two adaptive filtering algorithms, a simulation algorithm of a flexible manipulator system and simulation, identification and active vibration control algorithms of a flexible beam system. The algorithms are implemented on an 80486DX2 CISC processor, an 80386DX CISC processor, a SPARC TMS390S10 RISC processor, a T805 RISC processor, an 80i860 RISC processor and a TMS320C40 DSP device. The hardware and software resources and capabilities of the processors and the characteristics of the algorithms are discussed to provide a matching between the algorithms and the architectures. Finally, a comparison of the results of the implementations, on the basis of real-time computation performance, is made and discussed.

Self-Tuning Active Vibration Control in Flexible Beam Structures

This paper presents the design and performance evaluation of an adaptive active control mechanism for vibration suppression inflexible beam structures. A cantilever beam system in transverse vibration is considered. First-order central finite difference methods are used to study the behaviour of the beam and develop a suitable test and verification platform. An active vibration control algorithm is developed within an adaptive control framework for broadband cancellation of vibration along the beam using a single-input multi-output (SIMO) control structure. The algorithm is implemented on a digital processor incorporating a digital signal processing (DSP) and transputer system. Simulation results verifying the performance of the algorithm in the suppression of vibration along the beam, using single-input single-output and SIMO control structures, are presented and discussed.

Six degree-of-freedom active vibration control using the Stewart platforms

Multiple degree-of-freedom (DOF) vibration control systems are essential for precision control of a wide range of Space-borne structures as well as earth-based systems. This paper studies the design and control problems of a class of multiple DOF vibration isolation systems using the concept of a Stewart truss and Stewart platform mechanism. A novel geometric arrangement of a Stewart platform, called the "cubic configuration" is developed and used. A new design and analysis of actuators employing magnetostrictive material Terfenol-D is presented. Robust adaptive filter algorithms for active vibration control are formulated. Prototype hardware for a six degree-of-freedom active vibration isolation system with the "cubic configuration" of the Stewart platform has been implemented and tested. About 30 dB of vibration attenuation is achieved in real-time experiments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Six‐degree‐of‐freedom active vibration isolation using a stewart platform mechanism

AbstractIntelligent Automation, Inc. has performed a study of a six‐degree‐of‐freedom (dof) active vibration isolation system based on a Stewart platform mechanism to be used for precision control of a wide range of space‐based structures as well as earth‐based systems. This article presents part of the study results, which includes a new Terfenol‐D actuator design and analysis, a design of a Stewart platform as a vibration isolation device, and robust adaptive filter algorithms for active vibration control. Prototype hardware of a six‐dof active vibration isolation system has been implemented and tested. About 30 dB of vibration attenuation is achieved in real‐time experiments.