Showing papers on "Active vibration control published in 1996"
Book•
07 Mar 1996
TL;DR: In this article, the authors present a general analysis of active structural acyclic control (ASAC) for plate systems, including the use of piezoelectric error sensors in ASAC.
Abstract: Introduction to Mechanical Vibrations: Terminology. Single-degree-of-freedom (SDOF) Systems. Free Motion of SDOF Systems. Damped Motion of SDOF Systems. Forced Response of SDOF Systems. Transient Response of SDOF Systems. Multi-degree-of-freedom (MDOF) Systems. Free Motion of MDOF Systems. Forced Response of MDOF Systems. Damped Motion of MDOF Systems. Finite Element Analysis of Vibrating Mechanical Systems. Introduction to Waves in Structures: Longitudinal Waves. Flexural Waves. Flexural Response of an Infinite Beam to an Oscillating Point Force. Flexural Wave Power Flow. Flexural Response of an Infinite Thin Beam to an Oscillating Line Moment. Free Flexural Motion of Finite Thin Beams. Response of a Finite Thin Beam to an Arbitrary Oscillating Force Distribution. Vibration of Thin Plates. Free Vibration of Thin Plates. Response of a Thin Rectangular Simply Supported Plate to an Arbitrary Oscillating Force Distribution. Vibration of Infinite Thin Cylinders. Free Vibration of Finite Thin Cylinders. Harmonic Forced Vibration of Infinite Thin Cylinders. Feedback Control: Single-channel Feedback Control. Stability of a Single-Channel System. Modification of the Response of an SDOF System. The Effect of Delays in the Feedback Loop. The State Variable Approach. Example of a Two-degree-of-freedom System. Output Feedback and State Feedback. State Estimation and Observers. Optimal Control. Modal Control. Feedforward Control: Single Channel Feedforward Control. The Effect of Measurement Noise. Adaptive Digital Controllers. Multichannel Feedforward Control. Adaptive Frequency Domain Controllers. Adaptive Time Domain Controllers. Equivalent Feedback Controller Interpretation. Distributed Transducers for Active Control of Vibration. Active Control of Vibration in Structures: Feedforward Control of Finite Structures. Feedback Control of Finite Structures. Feedforward Control of Wave Transmission. Actuator Arrays for Control of Flexural Waves. Sensor Arrays for Control of Flexural Waves. Feedforward Control of Flexural Waves. Feedback Control of Flexural Waves. Active Isolation of Vibrations: Isolation of Periodic Vibrations of an SDOF System. Vibration Isolation From a Flexible Receiver the Effects of Secondary Force Location. Active Isolation of Periodic Vibrations Using Multiple Secondary Force Inputs. Finite Element Analysis of an Active System for the Isolation of Periodic Vibrations. Practical Examples of Multi-Channel Feedforward Control for the Isolation of Periodic Vibrations. Isolation of Unpredictable Vibrations from a Receiving Structure. Isolation of Vibrating Systems from Random External Excitation the Possibilities for Feedforward Control. Isolation of Vibrating Systems from Random External Excitation Analysis of Feedback Control Strategies. Isolation of Vibrating Systems from Random External Excitation Formulation in Terms of Modern Control Theory. Active Isolation of Vehicle Vibrations from Road and Track Irregularities. Active Structural Acoustic Control, I. Plate Systems: Sound Radiation by Planar Vibrating Surfaces the Rayleigh Integral. The Calculation of Radiated Sound Fields by Using Wavenumber Fourier Transforms. Sound Power Radiation From Structures in Terms of Their Multi-Modal Response. General Analysis of Active Structural Acoustic Control (ASAC) for Plate Systems. Active Control of Sound Transmission Through a Rectangular Plate Using Point Force Actuators. Active Control of Structurally Radiated Sound Using Multiple Piezoelectric Actuator Interpretation of Behaviour in Terms of the Spatial Wavenumber Spectrum. The Use of Piezoelectric Distributed Structural Error Sensors in ASAC. An Example of the Implementation of Feedforward ASAC. Feeback Control of Sound Radiation From a Vibrating Baffled Piston. Feedback Control of Sound Radiation From Distributed Elastic Structures. Active Structural Acoustic Control, II. Cylinder Systems: Coupled Cylinder Acoustic Fields. Response of an Infinite Cylinder to a Harmonic Forcing Function. Active Control of Cylinder Interior Acoustic Fields Using Point Forces. Active Control of Vibration and Acoustic Transmission in Fluid-Filled Piping Systems. Active Control of Sound Radiation From Vibrating Cylinders. Active Control of Sound in Finite Cylinder Systems. Control of Interior Noise in a Full Scale Jet Aircraft Fuselage. Appendix. References. Index.
1,055 citations
Book•
01 Jan 1996
TL;DR: Nelson and Elliott as mentioned in this paper summarized the principles underlying active vibration control and its practical applications by combining material from vibrations, mechanics, signal processing, acoustics, and control theory, and the reader will find particularly interesting the two chapters on the active control of sound radiation from structures: active structural acoustic control.
Abstract: This book is a companion text to Active Control of Sound by P.A. Nelson and S.J. Elliott, also published by Academic Press. It summarizes the principles underlying active vibration control and its practical applications by combining material from vibrations, mechanics, signal processing, acoustics, and control theory. The emphasis of the book is on the active control of waves in structures, the active isolation of vibrations, the use of distributed strain actuators and sensors, and the active control of structurally radiated sound. The feedforward control of deterministic disturbances, the active control of structural waves and the active isolation of vibrations are covered in detail, as well as the more conventional work on modal feedback. The principles of the transducers used as actuateors and sensors for such control strategies are also given an in-depth description. The reader will find particularly interesting the two chapters on the active control of sound radiation from structures: active structural acoustic control. The reason for controlling high frequency vibration is often to prevent sound radiation, and the principles and practical application of such techniques are presented here for both plates and cylinders. The volume is written in textbook style and is aimed at students, practicing engineers, and researchers.
234 citations
Patent•
12 Dec 1996TL;DR: In this article, the authors present an object for generating vibration and a vibration generating apparatus for allowing a single unit to provide a call signal by way of sound and body-sensible vibration.
Abstract: The present invention has an object to provide a method for generating vibration and a vibration generating apparatus for allowing a single unit to provide a call signal by way of sound and body-sensible vibration. According to the method for generating vibration of the invention, first and second vibration systems having different resonance frequencies from each other are magnetically coupled to each other and a state of energy externally supplied to the systems is selected thereby causing the first vibration system to vibrate relative to the second vibration system for generating a body-sensible vibration, for example. By changing the state of the energy, the second vibration system is caused to vibrate relative to the first vibration system for generating sound.
100 citations
TL;DR: In this article, the authors considered the active vibration control of cables and cable/structure systems with an active tendon controlling the axial displacement of the cable anchor point and demonstrated that a force feedback based on a collocated force sensor measuring the tension in the cable is feasible and that this control configuration can be associated with control laws with guaranteed stability properties.
Abstract: This paper considers the active vibration control of cables and cable/structure systems with an active tendon controlling the axial displacement of the cable anchor point. It is demonstrated that a force feedback based on a collocated force sensor measuring the tension in the cable is feasible and that this control configuration can be associated with control laws with guaranteed stability properties. Experimental results are presented on a cable with small sag and on a cable/structure system. They show that the control algorithm can provide the structure with several percent of active damping and that the parametric resonance does not occur when the natural frequency of the structure is twice that of the cable.
95 citations
Patent•
27 Sep 1996TL;DR: In this paper, a combination of passive isolation and active compensation over a selected bandwidth of frequencies below that over which passive isolation is most effective is presented. But the authors do not specify a specific method for its operation.
Abstract: A vibration isolation and precision pointing device, and a related method for its operation, for reducing vibrational disturbances on a payload platform, which is subject to vibration transmitted from a base platform and to other possible vibrational disturbances applied directly to the payload itself or to the payload platform. The invention includes a complementary combination of passive isolation and active isolation in parallel between the base and payload platforms, together with a precision positioning system that greatly reduces vibration at very low frequencies. Each isolation device, of which there are three pairs arranged to damp vibration in three axes, includes, in one embodiment, a passive spring to reduce coupling of vibration at higher frequencies and to fulfill a static load bearing function, and an active actuator element, in the form of a voice coil actuator, for applying active compensation over a selected bandwidth of frequencies below that over which passive isolation is most effective. Another disclosed form of each isolation device includes an elastic tube bendable by piezoelectric actuators and having a flexure that transmits the bending force to the payload platform along a single selected axis. In one preferred embodiment of the invention, three pairs of isolation devices are arranged on mutually orthogonal planes that intersect at the center of mass of the payload. As a result, translational vibration in the orthogonal planes is decoupled from rotation of the payload.
93 citations
TL;DR: In this paper, a generalized finite element formulation for active vibration control of a laminated plate integrated with piezoelectric polymer layers acting as distributed sensors and actuators is presented.
Abstract: A generalized finite element formulation for active vibration control of a laminated plate integrated with piezoelectric polymer layers acting as distributed sensors and actuators is presented. An eight-noded two-dimensional quadratic quadrilateral isoparametric element is derived for modeling the global coupled electroelastic behavior of the overall structure using higher-order shear deformable displacement theory. The procedure is illustrated with a simply supported plate in which the substrate is a symmetric (0/90/0 deg) graphite-epoxy laminate, and the sensor and actuator layers are made of polyvinylidene fluoride. Results show that significant reduction in vibration amplitude occurs because of increased damping through feedback.
90 citations
01 May 1996
TL;DR: In this paper, the performance of current state-of-the-art piezoelectric actuator devices is reviewed and compared, and general design guidelines for the selection and use of actuators for active vibration and control applications are given.
Abstract: Piezoelectric actuator technology is reviewed, and the performance of current state-of-the-art piezoelectric actuator devices estimated. Comparisons between actuator configurations show a wide range of available force and displacement performance. General design guidelines for the selection and use of piezoelectric actuators for active vibration and control applications are given. Examples of state-of-the-art actuator devices are given for each actuator case.
77 citations
TL;DR: In this paper, an optimal modal positive position feedback (OMPPF) algorithm was proposed to damp the vibrations of flexible structures by only using modal position signals to provide damping action to undamped structural modes.
Abstract: The vibrations of flexible structures are controlled by an optimal modal positive position feedback (OMPPF) algorithm whose control forces are generated by only using modal position signals to provide damping action to undamped structural modes. The suboptimal parameters of the OMPPF controller are obtained by casting the synthesis problem as an optimal control problem with incomplete state feedback. The effectiveness of the algorithm in damping out the vibration of flexible structures is validated experimentally using a cantilevered beam whose multimodes of vibration are controlled by a single piezoelectric actuator.
63 citations
TL;DR: In this article, a damping controller, developed using classical control theory, is added to the existing control system to suppress the vibrations of a micro/macro manipulator system and real-time measurements of macro-manipulator flexibility are used to adjust the motion of the micro manipulator to counteract structural vibrations.
Abstract: Inertial force damping control by micro-manipulator modulation is proposed to suppress the vibrations of a micro/macro manipulator system. The damping controller, developed using classical control theory, is added to the existing control system. Real-time measurements of macro-manipulator flexibility are used to adjust the motion of the micro-manipulator to counteract structural vibrations. Experimental studies using an existing micro/macro flexible-link manipulator testbed demonstrate the effectiveness of the proposed control scheme for both vertical and horizontal plane vibration.
57 citations
11 Dec 1996
TL;DR: In this paper, an energy regenerative type vibration damper and suspension system is introduced for active damper to reduce energy consumption without losing damping efficiency, where the electric energy is regenerated during high-speed motion of the actuator.
Abstract: A new energy regenerative type vibration damper and suspension systems are introduced. It is intended for active damper to reduce energy consumption without losing damping efficiency. An electro-dynamic actuator is used for the regenerative damper. The electric energy is regenerated during the high-speed motion of the actuator. For low-speed motion, an active or passive control algorithm is applied to the same actuator to achieve a good damping performance. This idea is applied to a single degree-of-freedom vibrating system. The experimental results show that the system has better performance than the pure passive damper system and can regenerate vibration energy.
56 citations
TL;DR: In this paper, an active vibration control of intelligent composite laminate structures containing an electro-rheological fluid is addressed, where complex shear modulus of the fluid itself is obtained as a function of imposed electric fields and excitation frequencies through a rotary oscillation test.
Abstract: This paper addresses an active vibration control of intelligent composite laminate structures containing an electro-rheological (ER) fluid. Firstly, complex shear modulus of the ER fluid itself is obtained as a function of imposed electric fields and excitation frequencies through a rotary oscillation test. By incorporating the measured complex modulus with a conventional sand wich beam theory, elastodynamic properties of the structures are then predicted. Subsequently, an experimental investigation is undertaken in order to identify modal characteristics such as damped natural frequencies, damping ratios, and mode shapes of the structures. As for the validation of the modeling methodology, the comparison between the predicted elastodynamic properties and the measured ones is performed. Characteristics of the ER fluid actuator explicitly representing the relationship between elastodynamic properties and imposed electric fields are also inferred. A control system model is then formulated by combining the a...
TL;DR: In this article, a composite differential equation of motion for a bimorph configured thin curved uniformly polarized piezoactuator pair surface bonded to a cylindrical shell is derived and approximate analytical expressions for the equivalent forces exerted by the actuator on a cylinrical shell are obtained.
Abstract: A composite differential equation of motion for a bimorph configured thin curved uniformly polarized piezoactuator pair surface bonded to a cylindrical shell is derived and the approximate analytical expressions for the equivalent forces exerted by the actuator on a cylindrical shell are obtained The in-phase configuration is studied The piezoactuators exertx and θ line forces and a uniform pressure load over the patch for in-phase configuration The in-phase forces show a saturation behavior with increase in thickness
TL;DR: In this article, an energy-based parametric control scheme is created to reduce the total system energy (the main structure mechanical energy plus the electrical and mechanical energies of the piezoelectric material and electrical circuit) while minimizing the energy flowing into the main structure.
Abstract: A structural vibration control concept, using piezoelectric materials shunted with real-time adaptable electrical networks, has been investigated. The variable resistance and inductance in an external RL circuit are used as control inputs. An energy-based parametric control scheme is created to reduce the total system energy (the main structure mechanical energy plus the electrical and mechanical energies of the piezoelectric material and electrical circuit) while minimizing the energy flowing into the main structure. Stability of the closed-loop system is proved. The performance of the controller is examined through analyzing a beam example. It is shown that the structure energy level and vibration amplitude can be suppressed effectively.
TL;DR: In this article, a flexible beam covered with shape memory alloy (SMA) layers is used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of, and adjusting the excitation to, the vibrating beam.
Abstract: The mathematical model of a flexible beam covered with shape memory alloy (SMA) layers is presented. The SMA layers are used as actuators, which are capable of changing their elastic modulus and recovery stress, thus changing the natural frequency of, and adjusting the excitation to, the vibrating beam. The frequency factor variation as a function of SMA Young's modulus, SMA layer thickness and beam thickness is discussed. Also control of the beam employing an optimal linear control law is evaluated. The control results indicate how the system reacts to various levels of excitation input through the non-homogeneous recovery shear term of the governing differential equation.
TL;DR: In this article, a single-axis active vibration reducing system for reducing vibrations in an object (12) in a single axis (20) is presented, where an actuator is positioned on the object to impart an actuation force along the actuator axis (26) without imparting substantial motion to the object other than in the vibrational axis.
Abstract: A single-axis active vibration reducing system for reducing vibrations in an object (12) in a single axis (20). The vibration isolation system enables the sensing (48) of motion of the center of mass (28) of an object (12) along a single axis (20) and, with the proper positioning of a single sensor-actuator (18, 24) pair with feedback operation, the dampening of vibrations of the object along that axis. Due to the positioning and alignment of the actuator (24), the vibration isolation system of the present invention does not introduce appreciable off-axis vibration. The vibration reducing system includes an actuator positioned (24) on the object to impart an actuation force along an actuator axis (26) to reduce vibrations of the object in the vibrational axis (20) without imparting substantial motion to the object other than in the vibrational axis (20).
TL;DR: In this paper, an active vibration control system is proposed for suppressing the small amplitude random vibrations in flexible beams, which is implemented on the basis of a floating-point digital signal processor.
TL;DR: In this article, a finite element model of a multibearing rotor system is presented, where the effects of rotary inertia, gyroscopic moments, internal viscous and hysteretic damping and shear deformations have been included.
01 Aug 1996
TL;DR: In this article, the construction of a dynamic absorber incorporating active vibration control is described, where the absorber is a 2 degree of freedom spring-lumped mass system sliding on a guide pillar, with two interconnections.
Abstract: 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 inter...
TL;DR: In this paper, the authors investigate two strategies for the active control of plate vibrations, using distributed sensors and actuators (PVDF patches) working on a wide frequency band.
Abstract: The aim of the present paper is to investigate two strategies for the active control of plate vibrations, using distributed sensors and actuators (PVDF patches) working on a wide frequency band. The two strategies correspond to the two ends of a spectrum ranging from very robust/less efficient schemes (analog static output feedback) to less robust/very efficient schemes (here ‘frequency shaped LQG’).
Both have been experimentally tested and have given successful attenuations; the efficiency of both approaches is demonstrated on sensor signals involved in the control loop as well as on radiated pressure measurements, which constitute an independent index of performance.
It is shown that ‘frequency shaped LQG’ is a viable approach to feedback control of lightly damped structures, and that its robustness can be enhanced through a careful design.
LQG is a model-based method, and hence requires the modeling of the active structure. Two approaches are investigated in this paper: a finite element model and a identified model built from the experimentally measured transfer functions.
TL;DR: In this paper, the active control of vibration transmission in stiffened beams, plates and cylinders, using as control sources piezoceramic stack actuators placed between the flange of a stiffener and the structure surface, has been examined theoretically and experimentally.
TL;DR: In this article, an actuator power dissipation reduction circuit reduces high frequency energy transients with in-series inductors to prevent heat inducing eddy currents in the actuator without additional current flow in the power amplifier.
Abstract: Vibrational energy in a first frequency range within a vehicle or the like is controlled by an active vibration control system which includes a sensor, controller, driver, actuator and actuator power dissipation reduction circuit. The controller provides a control signal to a Class-D power amplifier operating at a second higher frequency to generate an output signal to the actuator in the frequency range of the noise/vibration to be controlled resulting in a force output from the actuator controlling vibration and/or noise in a passenger compartment of the vehicle. The actuator power dissipation reduction circuit reduces high frequency energy transients with in-series inductors to prevent heat inducing eddy currents in the actuator without additional current flow in the power amplifier.
TL;DR: In this paper, a validated vibration characterisation strategy is proposed based on sensitivity analysis for improved vibration control of an ultrasonic metal forming process, and the result is a design procedure for improving the reliability of metal forming processes.
TL;DR: In this paper, a hybrid-type active vibration isolation system that uses electromagnetic and pneumatic force is developed, and a new control algorithm adopting neural networks is proposed, and the characteristics of the hybrid system proposed in the paper were investigated via computer simulation and experiments.
TL;DR: In this paper, the authors proposed a method of μ-synthesis based on the descriptor form representation to deal with parameter uncertainties independently, and applied it to a 2-mass system with parameters of the torsional constant and the load inertia.
01 May 1996
TL;DR: In this paper, an active suppression of chatter instabilities in an Octahedral Hexapod Milling (OHM) machine is discussed. And an active vibration control design to minimize vibration at the tool tip is also integrated into the simulation.
Abstract: This paper describes a design study to determine the feasibility of integrating active control into a milling machine to enhance milling-process performance. The study described herein focuses on the active suppression of chatter instabilities in an Octahedral Hexapod Milling (OHM) machine. Structural dynamics contributing to chatter instabilities were described using calibrated finite element models, which were coupled with a tool-workpiece interaction model for purposes of determining, by simulation, machine performance enhancement due to active control. An active vibration control design to minimize vibration at the tool tip was also integrated into the simulation. Active control subcomponent and actuator size requirements were determined from the modeling and simulations. The study showed that active control is a feasible solution for suppressing chatter instabilities, allowing the metal removal rate of the OHM machine to be increased by roughly a factor of two.
TL;DR: In this article, an active vibration control of an axially moving string using space feed-forward and feedback controllers is presented, and closed-form results for the transverse response of both the uncontrolled and controlled string are given in the s domain.
Abstract: Active vibration control of an axially moving string using space feedforward and feedback controllers is presented. Closed-form results for the transverse response of both the uncontrolled and controlled string are given in the s domain. The space feedforward controller is established by employing the idea of wave cancellation. The proposed control law indicates that vibration in the region downstream of the control force can be cancelled. With the space feedforward control, the mode shapes of the axially moving string are changed such that the free response tends to zero in the downstream region. An interesting physical interpretation is that the control force acts effectively as a holder (active support) which limits the vibration of the string to the upstream region and eliminates any vibration in the downstream region. Simulation results show that the response of the string to both sinusoidal and random excitations is suppressed by applying the space feedforward control. The feedback controller is introduced to attenuate the response of the string due to undesired disturbances in the downstream.
TL;DR: In this paper, the authors describe a passive-active system for passive vibration control followed by active vibration control on an air-mounted sensor-actuator pair, where the electrical feedback loop includes generation by the sensor of a signal resulting from the local vibration of the foundation-securing plate, generation by a processor/controller of the signal derived from the sensor's signal, and exertion upon the mounted sensor's paired actuator of a vibratory force commanded by the processor's signal.
Abstract: The invention is uniquely "passive-active" in that it brings to bear, sequentially and complementarily, passive vibration control followed by active vibration control. A conventional mount (such as an air mount) is accommodated so as to include, at the mount's foundation-securing plate, at least one motion sensor and at least one vibratory actuator. Each sensor is correlated with an actuator. For each sensor-actuator pair, the electrical feedback loop includes generation by the sensor of a signal resulting from the local vibration of the foundation-securing plate, generation by a processor/controller of a signal derived from the sensor's signal, and exertion upon the foundation-securing plate by the sensor's paired actuator of a vibratory force commanded by the processor/controller's signal. Many preferred embodiments of the inventive apparatus, system and method collocate each sensor with its paired actuator and implement a conventional vibration suppression algorithm involving collocated velocity feedback.
TL;DR: In this article, the electro-mechanical behavior of a piezoelectric stack as a sensor, actuator, vibration isolator and absorber is analyzed in detail.
Abstract: Considering a piezoelectric stack to be connected with structures at both ends in order to sense or control the relative displacement or velocity between structures, the electro-mechanical behavior of the stack as a sensor, actuator, vibration isolator and absorber is analysed in detail. Analytical results show that it is possible to apply the piezoelectric stack as a velocity sensor. Meanwhile, when it is employed as an actuator, its actuating force and electric admittance considerably change with the variation of the impedance of the two connected structures. Moreover, the results demonstrate that the isolation and suppression of structural vibration could be realized by the direct method, where velocity of controlled structures is directly annihilated by counter-action of the piezoelectric stack imposed by an external electric field, and the active damping method, where structural velocity is attenuated by the increase of the damping coefficient induced by the stack. However, the results also illustrate that induction of the positive active damping coefficient by the stack with the feedback of sensing electric current is conditional for the suppression of structural vibration while it is unconditional for isolation of vibration. This implies that it is not always possible in the whole frequency range to suppress the structural vibration with the active damping method: on the contrary, instability of structural vibration could be triggered.