Active Vibration Control Design Research Articles

Dynamic simulation and active vibration control design of an ultra-precision fly-cutting machine tool

Dynamic simulation and active vibration control design of an ultra-precision fly-cutting machine tool

Fault-tolerant Sliding Mode Controller and Active Vibration Control Design for Attitude Stabilization of a Flexible Spacecraft in the Presence of Bounded Disturbances

This paper concerns vibration control and attitude stabilization of a flexible spacecraft with faulty actuators. The PID-based sliding mode fault-tolerant scheme is developed to preserve the system against bounded external disturbances, rigid-flexible body interactions, and partial actuator failures. The proposed control law, which combines the advantages of the PID and SMC, is proposed to enhance the robustness and reduce the steady state errors while reducing complexity and the computational burden and preserving the great properties of the SMC controller. It has been shown that the SMC controller is effective in accommodating different actuator fault scenarios and behaves healthily. Additionally, an active vibration control (AVC) law utilizing a strain rate feedback (SRF) algorithm and piezoelectric (PZT) sensors/actuators is activated during the maneuver to compensate for residual vibrations resulting from attitude dynamics and actuator failures. Numerical simulations demonstrate the proposed schemes' superiority in fault tolerance and robustness compared to conventional approaches.

A coupled efficient layerwise finite element model for free vibration analysis of smart piezo-bonded laminated shells featuring delaminations and transducer debonding

This paper presents a computationally efficient multifield finite element (FE) model for accurate analysis of smart composite and sandwich shells equipped with piezoelectric patch actuators and sensors, featuring multiple delaminations and transducer debonding. It employs a facet shell element with four physical nodes and one electric node, based on the third order zigzag theory approximations for displacements and a piecewise quadratic through-thickness variation for the electric potential. A hybrid point-least squares method recently proposed by the authors is extended to impose the condition of continuity of the nonlinear displacement field at the delamination, debonding, and patch fronts. The methodology is generic for multiple patch transducers, delaminations, and debonding, occurring at any arbitrary interface and in-plane locations. The model shows excellent accuracy in comparison with the coupled full-field 3D FE solutions, for the natural frequencies and complex global, local and hybrid mode shapes of delaminated smart composite shells and soft-core sandwich plates, with partially debonded actuators and sensors. The developed model will be of immense use for the design of active vibration control and structural health monitoring strategies for smart laminated shell-type structures featuring such damages.

Design and implementation of multichannel adaptive active vibration control with online secondary path modeling using piezoelectric transducers patches

Adaptive active vibration control (AAVC) is an effective way for reducing structure vibration at low frequency. AAVC methodology is preferred in AVC system due to its self-adjustment ability to adapt to varying dynamics of the structure. The Filtered-X Least Mean Square (FXLMS) algorithm is widely implemented in active control applications. Accurate secondary path models are very crucial for the implementation in multichannel AAVC system based on FXLMS algorithm. The auxiliary random noise technique is often applied to achieve secondary path modeling (SPM) during online operation. This paper proposes a new multichannel AAVC methodology based on online SPM method. The online SPM error is estimated indirectly to reduce the interaction between the AAVC controller and the online SPM filter. A new variable step-size (VSS) strategy for online SPM filter is proposed based on the estimated online SPM error. A simple but effective auxiliary noise power scheduling (ANPS) method is proposed to eliminate the contribution of the auxiliary noise on the residual vibration. A series of multi-channel AAVC experiments on a cantilever epoxy resin plate with PZT sensors and actuators are presented to demonstrate the performance of the proposed methodology. Experiment results indicate that the proposed method provides very good online SPM accuracy, and the vibration of the smart cantilever plate has been effectively attenuated with high convergence rate.

Boundary vibration control for a flexible Timoshenko robotic manipulator

The authors investigate the dynamic modelling problem and the active vibration control design problem for a flexible Timoshenko robotic manipulator in this study. For the practical robotic manipulator, the authors analyse the dynamic characteristic considering the shear deformation and elastic deflection of the flexible arm link and describe this flexible system with a coupled partial differential equation and ordinary differential equations (PDE–ODEs) model. Furthermore, the authors design the active vibration control and disturbance observers to solve the vibration problem of the flexible robotic manipulator under the external disturbances, namely, to reduce the shear deformation and the deflection of the flexible Timoshenko link. Besides, the manipulator is driven to track the given angular position with an active angular controller, simultaneously. The effectiveness of the designed vibration control laws is analysed by the theoretical analysis and verified by the numerical simulation.

Active vibration control design using the Coral Reefs Optimization with Substrate Layer algorithm

Active vibration control (AVC) via inertial-mass actuators is a viable technique to mitigate human-induced vibrations in civil structures. A multi-input multi-output (MIMO) AVC has been previously proposed in the literature to simultaneously find the sensor/actuator pairs’ optimal placements and tune the control gains. However, the method involved local gradient-based methods, which is not affordable when the number of possible locations of actuators is large. In this case, the computation time to obtain a local solution may be huge and unaffordable, which limits the number of test points and/or actuators/sensors considered. This paper proposes an alternative approach based on a recently proposed meta-heuristic, the Coral Reefs Optimization (CRO) algorithm. More concretely, an enhanced version of the CRO is considered, the Coral Reefs Optimization with Substrate Layer (CRO-SL). The CRO-SL is a competitive co-evolution algorithm in which different exploration procedures are jointly evolved within a single population of potential solutions to the problem. The proposed algorithm is thus able to promote competition among different search methods to solve hard optimization problems. In terms of structural design, this work provides an important step to improve the applicability of AVC systems to real complex structures (with a large number of vibration modes and/or with a large number of test points) by achieving global optimum designs with affordable computation time. A finite element model of a real complex floor structure is used to illustrate the contributions of this paper.

Velocity feedback damping of piezo-actuated wings

A geometrical nonlinear model of thin-walled beams with fiber-reinforced and piezo-composite is developed for smart aircraft wing structures. Some non-classical effects such as warping inhibition and three-dimensional (3-D) strain are accounted for in the beam model. The governing equations and the corresponding boundary conditions are derived using the Hamilton’s principle. The Extended Galerkin’s Method is used for the numerical study. A negative velocity feedback control algorithm is adopted to control the aircraft wing response. The effective damping performance is optimized by studying anisotropic characteristics of piezo-composite and elastic tailoring of the fiber-reinforced host structure. The relations between active vibration control effect and design factors, such as the size and position of piezo-actuator are investigated in detailed.

Active Vibration Control Design Method Based on Transfer Matrix Method for Multibody Systems

AbstractThe efficient vibration control of complex multibody systems is an important issue in engineering design and has drawn substantial attention in the field of multibody system dynamics and co...

A modal H∞-norm-based performance requirement for damage-tolerant active controller design

Damage-tolerant active control (DTAC) is a recent research area that encompasses control design methodologies resulting from the application of fault-tolerant control methods to vibration control of structures subject to damage. The possibility of damage occurrence is not usually considered in the active vibration control design requirements. Damage changes the structure dynamics, which may produce unexpected modal behavior of the closed-loop system, usually not anticipated by the controller design approaches. A modal H∞ norm and a respective robust controller design framework were recently introduced, and this method is here extended to face a new DTAC strategy implementation. Considering that damage affects each vibration mode differently, this paper adopts the modal H∞ norm to include damage as a design requirement. The basic idea is to create an appropriate energy distribution over the frequency range of interest and respective vibration modes, guaranteeing robustness, damage tolerance, and adequate overall performance, taking into account that it is common to have previous knowledge of the structure regions where damage may occur during its operational life. For this purpose, a structural health monitoring technique is applied to evaluate modal modifications caused by damage. This information is used to create modal weighing matrices, conducting to the modal H∞ controller design. Finite element models are adopted for a case study structure, including different damage severities, in order to validate the proposed control strategy. Results show the effectiveness of the proposed methodology with respect to damage tolerance.

Design and analysis of active vibration and stability control of a bio-inspired quadruped robot

Design and analysis of active vibration and stability control of a bio-inspired quadruped robot

Design and analysis of active vibration and stability control of a bio-inspired quadruped robot

The main aim of this research work is to design and develop a bio-inspired quadruped robot for operating in an uneven terrain. The present work focus on development of a gear-train power transmission mechanism, which is more efficient, as the gear assemblies can be optimised for generating different locomotion patterns. The kinematic and dynamic analysis of the limb analysis has been carried out. The modelling of mechanism and measurement and motion analysis has been carried out using ProE Wildfire software and the results have been presented in this paper.

Enhancing vibration suppression in a periodically excited flexible beam by using a repetitive model predictive control strategy

This experimental study was conducted for the purpose of enhancing vibration suppression in periodically excited flexible structures by using model predictive control (MPC), an advanced optimal-control method that can be used to handle system constraints at all sampling steps. The Hildreth optimization solver was used to examine two MPC strategies, a basic MPC strategy and a repetitive MPC (RMPC) strategy, and the active vibration-control design and performance of the strategies were evaluated. The disturbance-rejection performance of the applied MPC methods was specifically investigated by using periodic input signals to excite a piezoelectric flexible beam. These comparative studies performed together with parameter analysis offer a design guideline for achieving satisfactory vibration-suppression performance and further demonstrate that the applied RMPC method can effectively suppress the vibration of a flexible-structure system.

Active vibration control of a full scale aircraft wing using a reconfigurable controller

This work highlights the design of a Reconfigurable Active Vibration Control (AVC) System for aircraft structures using adaptive techniques. The AVC system with a multichannel capability is realized using Filtered-X Least Mean Square algorithm (FxLMS) on Xilinx Virtex-4 Field Programmable Gate Array (FPGA) platform in Very High Speed Integrated Circuits Hardware Description Language, (VHDL). The HDL design is made based on Finite State Machine (FSM) model with Floating point Intellectual Property (IP) cores for arithmetic operations. The use of FPGA facilitates to modify the system parameters even during runtime depending on the changes in user’s requirements. The locations of the control actuators are optimized based on dynamic modal strain approach using genetic algorithm (GA). The developed system has been successfully deployed for the AVC testing of the full-scale wing of an all composite two seater transport aircraft. Several closed loop configurations like single channel and multi-channel control have been tested. The experimental results from the studies presented here are very encouraging. They demonstrate the usefulness of the system’s reconfigurability for real time applications.

Semi-modal active vibration control of plates using discrete piezoelectric modal filters

Modal sensors and actuators working in closed loop enable to observe and control independently specific vibration modes, reducing the apparent dynamical complexity of the system and the necessary energy to control them. Modal sensors may be obtained by a properly designed weighted sum of the output signals of an array of sensors distributed on the host structure. Although some works found in the literature present techniques for designing and implementing modal filters based on a given array of sensors, the effect of the sensors’ distribution on the modal filter performance has received little attention. Recent studies have shown that some parameters, such as size, shape and location of the sensors, are very important for the performance of the resulting modal filters. This work presents a methodology for the design of semi-modal active vibration control of a rectangular plate using modal filters based on arrays of piezoelectric sensors. The geometric distribution of the array of piezoelectric sensors bonded to a rectangular plate is numerically optimized to improve the effectiveness and frequency range of a set of modal filters. An experimental implementation of the modal filters is carried out in order to validate their performance. It is shown that proper setup of weighting coefficients is an important requirement. Then, two simple control laws, namely direct velocity feedback and positive position feedback, using the modal filter output are designed and implemented. It is shown that modal filtering allows to effectively control selected vibration modes with quite simple signal processing requirements.

Adaptive Strategy to Damage-Tolerant Active Control

Smart structure development is a recent trend that has been intensely researched, including multidisciplinary new technologies and methods. Damage-tolerant active control is a new research area, applying fault-tolerant control methods to mechanical flexible structures, which demands spatial constraints not commonly found in the general control approach. A proposed strategy, applied to active vibration controller design and considering the possibility to face damage consequences, are here introduced and assessed through finite elements models of healthy and damaged structures, used to simulate achieved performance. A Lamb wave technique is adopted to detect and localize damage, associated to spatial norm controller design and reconfiguration, to attain an acceptable performance to the damaged structure. Results illustrate the pertinent concepts and permit to expect successful application of the proposed approach.

Active modal damping control of a smart truss structure using a self-organizing fuzzy controller

This paper presents design, implementation and experimental results of active vibration control of a truss structure using a pair of piezoelectric ceramic stack actuators. To reduce the vibrations caused by an impulse force, two active strut members are installed along a vertical of the base bay of the truss. The active strut element consists of a piezoelectric ceramic actuator stack, a force transducer and mechanical interfaces. A self-organizing fuzzy controller (SOFC) is designed to suppress vibration of the truss. The SOFC, which uses the input and output history in its fuzzy rules, is designed to maximize modal damping of a constructed truss structure. Experimental results illustrate that the active piezoceramic strut actuators and the SOFC can effectively reduce vibration of the truss.

A new method for accurately determining the modal equivalent stiffness ratio of bonded piezoelectric structures

This paper describes new methods for measuring the modal equivalent stiffness ratios and modal electromechanical coupling coefficients of piezoelectric elements attached to a host structure such as a beam. Modal equivalent stiffness ratios and modal electromechanical coupling coefficients are essential for estimating the performance and determining an optimum design of active vibration control and passive vibration suppression systems that use piezoelectric elements. Accurate determination of these modal parameters is also useful for other systems including piezoelectric sensors and energy generators. This paper not only describes the measurement methods but also presents the theoretical formulations derived by taking into account the effect of adhesive bonds. The formulations in this paper demonstrate the necessity of experimental measurements and the accuracy enhancements that the theoretical estimations can provide. Conventional methods for obtaining the modal equivalent stiffness ratios are sensitive to measurement errors, which result in the loss of accuracy, rendering these methods unreliable for many practical applications. The proposed methods use an inductor instead of an open circuit to address the abovementioned issue and, thereby, provide significant improvement in the accuracy. Because the loss factors of the experimental apparatus tend to compromise the accuracy of the proposed methods, a method using a negative resistor is proposed, theoretically analyzed, and confirmed to eliminate some of the errors introduced by loss factors. The advantages of the proposed methods and the effectiveness of theoretical analysis, considering the effect of adhesive bonds, are verified experimentally.

Design of active vibration control for launcher of multiple launch rocket system

This study deals with analysis and design of active vibration control algorithm for the launcher of multiple launch rocket system (MLRS). The new method proposed is that guidance and control package are equipped on launcher, not rocket, to active control motion of launcher for the first time. It has interesting advantages as follows: (1) active vibration control is more competent, more pliable, and more realizable in engineering compared to passive vibration control. (2) The guidance and control package will not be destroyed. In this study, transfer matrix method of multibody system is used to build the controlled dynamic model of MLRS. This method does not need the global dynamic equations of system and has high computational rate. Independent modal space control method and optimal control theorem are applied to design control law with feedforward and feedback control loops. The modal filters are designed as the state estimator to obtain the modal coordinates and their derivatives. Modal disturbance force observer is designed to obtain modal disturbance force. Pulse-width pulse-frequency (PWPF) modulator is used to modulate the continue control force command into discrete control force in order to avoid high non-linear control action of pulse thruster. The control force provided by pulse thruster and parameters of PWPF are obtained. The numerical results indicate that control law determined by optimal theorem integrated with PWPF modulator achieves good performance in active vibration control of launcher. This study improves the performance of MLRS in resisting impact and provides theoretical support for accurate launch.

Design of robust-stable and quadratic finite-horizon optimal active vibration controllers with low trajectory sensitivity for uncertain flexible mechanical systems using an integrative computational method

By integrating the robust stabilizability condition, the orthogonal-functions approach (OFA), and the hybrid Taguchi-genetic algorithm (HTGA), an integrative method is presented in this paper to design the robust-stable and quadratic finite-horizon optimal active vibration controller with low trajectory sensitivity such that (i) the flexible mechanical system with elemental parametric uncertainties can be robustly stabilized, and (ii) a quadratic finite-horizon integral performance index including a quadratic trajectory sensitivity term for the nominal flexible mechanical system can be minimized. In this paper, the robust stabilizability condition is proposed in terms of linear matrix inequalities (LMIs). Based on the OFA, an algebraic algorithm only involving the algebraic computation is derived for solving the nominal flexible mechanical feedback dynamic equations. By using the OFA and the LMI-based robust stabilizability condition, the robust-stable and quadratic finite-horizon optimal active vibration control problem for the uncertain flexible mechanical dynamic systems is transformed into a static constrained-optimization problem represented by the algebraic equations with constraint of LMI-based robust stabilizability condition; thus greatly simplifying the robust-stable and quadratic finite-horizon optimal active vibration control design problem. Then, for the static constrained-optimization problem, the HTGA is employed to find the robust-optimal active vibration controllers of the uncertain flexible mechanical systems. A design example is given to demonstrate the applicability of the proposed integrative approach.

Model-based design and experimental validation of active vibration control for a stress ribbon bridge using pneumatic muscle actuators

This paper describes the development of an active vibration control system for a light and flexible stress ribbon footbridge. The 13 m span carbon fiber reinforced plastic (CFRP) stress ribbon bridge was built in the laboratory of the Department of Civil and Structural Engineering, Berlin Institute of Technology. Its lightness and flexibility result in high vibration sensitivity. To reduce pedestrian-induced vibrations, very light pneumatic muscle actuators are placed at handrail level, introducing control forces. First, a reduced discretized analytical model is derived for the stress ribbon bridge. To verify the analytical prediction, experiments without feedback control are conducted. Based on this model, a delayed velocity feedback control strategy is designed. To handle the nonlinearities of the muscle actuator, a subsidiary force control is implemented. Then the control performance from numerical simulation is verified by experiments under free vibration. As a result, analytical analyses agree well with experimental results. It is demonstrated that handrail-introduced forces can efficiently control the first mode response.