Vibration Control Experiments Research Articles

Multi-channel decentralized decoupling FxLMS algorithm and active vibration control experiment

When vibrations generated by marine machinery propagate through a ship’s hull into the ocean, they produce low-frequency radiated noise with distinct “acoustic fingerprint” characteristics. This noise, characterized by stable and concentrated energy, long transmission distances, and difficulty in elimination, becomes the primary target for enemy sonar detection. Active vibration isolation serves as a critical method for reducing low-frequency vibrations in ships and enhancing their acoustic stealth performance. However, control challenges persist, including multi-frequency excitation, frequency fluctuation, multi-channel coupling, and slow convergence speed. To address these issues, this paper introduced an innovative multi-channel decentralized decoupling filtered-x least mean square (DMFxLMS) algorithm. Firstly, a recursive least squares identification algorithm with a forgetting factor was proposed, taking into account the characteristics of single-input, multi-output and multi-input, and multi-output control systems, effectively enhancing the algorithm’s convergence speed and control accuracy. Secondly, based on the decentralized decoupling control concept, the multi-channel control system was simplified into parallel single-channel control loops. The control weight coefficient updates were only related to adjacent error signals, significantly reducing the algorithm’s computational complexity. Thirdly, an anti-impact link was designed to improve the algorithm’s robustness, considering the interference caused by other mechanical equipment during the control process. The influence of abnormal error signals in the control weight coefficient correction term was suppressed, and a percentage function was introduced to limit the output signal. Finally, the feasibility and effectiveness of the DMFxLMS algorithm were verified through simulations and experiments. The results demonstrated that the DMFxLMS algorithm achieved significant control effects for both constant frequency line spectrum excitation and frequency fluctuating line spectrum excitation, fulfilling the objective of reducing base vibration. The DMFxLMS algorithm exhibited fast convergence and excellent robustness, making it suitable for practical engineering applications.

Active vibration control for thin curved structures using dielectric elastomer actuators

This study proposes an active vibration control technique for pipe structures using dielectric elastomer actuators (DEAs). Vibrations in pipe structures must be eliminated to improve their mechanical reliability, and active vibration control techniques can be applied for effective vibration suppression. Soft actuators, which can completely fit pipe structures with complex-shaped surfaces, are required to transfer their vibration reduction forces to the target. DEA is suitable for this kind of target structure because DEA is characterized by high stretchability, flexibility, large deformation, and fast response. By applying the DEA, the effectiveness of vibration control for the pipe structure was experimentally demonstrated. A stacked DEA was fabricated and attached to the target structure. Its shape and placement were determined based on a modal analysis of the target structure. A control system, in which the controller for the active vibration control was designed based on H∞ control theory, was composed. The vibration control experiment was conducted using the controller with a digital control system, and the vibration reduction effect was evaluated based on the frequency response of the target pipe structure.

Simulation and Experiment of Active Vibration Control Based on Flexible Piezoelectric MFC Composed of PZT and PI Layer.

In order to improve the vibration suppression effect of the flexible beam system, active control based on soft piezoelectric macro-fiber composites (MFCs) consisting of polyimide (PI) sheet and lead zirconate titanate (PZT) is used to reduce the vibration. The vibration control system is composed of a flexible beam, a sensing piezoelectric MFC plate, and an actuated piezoelectric MFC plate. The dynamic coupling model of the flexible beam system is established according to the theory of structural mechanics and the piezoelectric stress equation. A linear quadratic optimal controller (LQR) is designed based on the optimal control theory. An optimization method, designed based on a differential evolution algorithm, is utilized for the selection of weighted matrix Q. Additionally, according to theoretical research, an experimental platform is built, and vibration active control experiments are carried out on piezoelectric flexible beams under conditions of instantaneous disturbance and continuous disturbance. The results show that the vibration of flexible beams is effectively suppressed under different disturbances. The amplitudes of the piezoelectric flexible beams are reduced by 94.4% and 65.4% under the conditions of instantaneous and continuous disturbances with LQR control.

An Improved Feedforward-Robust Algorithm for Active Vibration Control of Helicopter Maneuver Flight

To solve the problem of secondary path mutation and external disturbance abrupt changes during helicopter maneuver flight, the previous research proposed a hybrid active vibration control law. To improve the engineering applicability, the original algorithm is ameliorated to the least mean square-input-output-based robust (LMS-IOBR) algorithm. The system model within the target frequency band can be identified through the input-output data to avoid constructing complex state observers. In addition, the output form of the feedback controller is constructed by an autoregressive moving average model with extra input, which is beneficial to improve operational efficiency. Numerical simulations demonstrate that compared with the original algorithm, controller real-time computation can be reduced by 52% with control effects guaranteed at the same time. Furthermore, to verify the effectiveness and adaptability of LMS-IOBR, multi-input multioutput vibration control experiments are carried out on a specially developed simple platform for simulating helicopter maneuver states. Comparative tests in various typical states are performed between the LMS-IOBR and the multichannel least mean square algorithm. Under the complex circumstances of simulating continuous subduction uplift, the peak response of closed-loop system attenuates by 80% and 70%, and the vibration of two points is reduced to 15% and 20%, respectively, within 3 s. The experimental results demonstrate that the proposed LMS-IOBR algorithm shows stronger transient adaptability and robustness against external disturbance excitation and secondary channel mutation in helicopter maneuver flight.

Research on Structure Design and Control Method of Magnetorheological Suspension Based on Improved Fruit Fly Optimization Algorithm

To reduce engine vibration, a semi-active controlled magnetorheological suspension is designed. First, the magnetic circuit of the new magnetorheological suspension is simulated. Furthermore, the non-parametric forward and inverse dynamic models of the magnetorheological suspension with the Elman neural network are established, where the modeling results and accuracy are analyzed. Second, according to the characteristics of semi-active vibration control of engine suspension, an improved fruit fly optimized proportional-integral-differential (PID) controller is proposed. Compared with the original fruit fly optimized PID controller and particle swarm optimization PID controller, the control strategies based on the proposed methods are simulated by MATLAB. Then, a vibration control experiment is carried out under different control strategies. The simulation and experiment results show that the PID controller based on the improved fruit fly optimization algorithm has the advantages of short adjustment time and fast dynamic response.

Multi-agent cooperative structural vibration control of three coupled flexible beams based on value decomposition network

Multi-coupled flexible body (MCFB) structure has the characteristics of small damping, close modes and coupled vibration, and the structural vibration is difficult to freely attenuate, which will lead to rapid fatigue failure of the structure. In order to suppress the vibration of the MCFB system quickly, a system identification scheme and a multi-agent reinforcement learning (MARL) scheme are proposed to obtain the cooperative controller. The mathematical model of the three-coupled flexible beam (TCFB) system is identified by wavelet analysis method, particle swarm optimization (PSO) and sinusoidal excitation response method. Based on value decomposition network (VDN) and deterministic policy gradient (DPG), a cooperative MARL framework is constructed to obtain the controller (VDN-DPG controller). The cooperative VDN-DPG controller is applied to the vibration control simulation and experiments of the TCFB system, and compared with proportional–derivative (PD) control without cooperation. The results show that the performance of the VDN-DPG controller is better than that of the PD controller, which verifies the effectiveness of the multi-agent cooperative control scheme based on VDN-DPG.

Vibration analysis and control of cracked beam using finite element method by using ANSYS

PurposeThe purpose of this paper is to develop an organized structure for damage detection of a cracked cantilever beam using finite element method and experimental method technique.Design/methodology/approachDue to presence of cracks the dynamic characteristics of structure change. The change in dynamic behavior has been used as one of the criteria of fault diagnosis for structures. Major characteristics of the structure which undergo change due to presence of crack are: natural frequencies, the amplitude responses due to vibration and the mode shapes. Therefore, an attempt has been made to formulate a smart technique for minimizing the amplitude of vibration for crack cantilever beam structures. In the analysis both single and double cracks are taken into account.FindingsThe results of the active vibration control experiments proved that piezoelectric sensor/actuator pair is an effective sensor and actuator configuration for active vibration control to reduce the amplitude of vibration for closed-loop system.Originality/valueIt is necessary that structures must safely work during its service life, but damages initiate a breakdown period on the structures which directly affect the industrial growth. It is a recognized fact that dynamic behavior of structures changes due to presence of crack. It has been observed that the presence of cracks in structures or in machine members leads to operational problem as well as premature failure.

An excellent harmonic feedforward-sliding mode output feedback hybrid algorithm for helicopter active vibration control

Higher harmonic control algorithms in frequency domain are generally used for active vibration control of helicopter fuselage. However, these algorithms are inefficient to control transient vibration caused by rapid changing of helicopter flight conditions. Time domain feedback algorithms are efficient to control the transient vibration. In this paper, an excellent harmonic feedforward-sliding mode output feedback hybrid algorithm by combining frequency and time domain algorithms is presented to improve the effect and performance of active vibration control of helicopter fuselage, meanwhile to avoid the requirement of full state information of control system due to using the time domain algorithms. The convergence criterions of the harmonic feedforward algorithm and the hybrid algorithm are theoretically derived, respectively. The convergence speed of the hybrid algorithm is theoretically proved to be faster than that of the harmonic feedforward algorithm. Active vibration control simulation and experiment on a dynamically similar and geometrically scaled frame structure of a helicopter fuselage verify the proposed hybrid algorithm with excellent control effect and performance.

Vibration control of three coupled flexible beams using reinforcement learning algorithm based on proximal policy optimization

In order to suppress the vibration of a class of multi-coupling flexible beams, a three-coupling flexible beam experimental device is constructed. The vibration characteristics and active vibration control algorithms of three coupled flexible beams are studied. Due to the complex residual vibration of multi-coupled flexible beam structure, which shows the interaction between beams and close frequency characteristics, the dynamic model of coupled flexible beam structure is established by finite element method (FEM) and its theoretical modal analysis is carried out. Furthermore, the parameters of the experimental system are identified, and the close modal frequencies and damping ratios of the actual system are obtained. The characteristics of close modal vibration are verified. A reinforcement learning (RL) vibration controller based on proximal policy optimization (PPO) algorithm is designed. The algorithm mainly includes actor neural network and critic neural network, which are used to approximate the control strategy and evaluate state respectively. Based on theoretical modeling and experimental identification correction model, the agent learns offline, and then transfers the learned policy parameters to the experimental system for vibration control experiments. The experimental results demonstrate that the designed RL controller can effectively suppress the residual vibration of three coupled flexible beams.

Reduced-Order Extended State Observer-Based Sliding Mode Control for All-Clamped Plate Using an Inertial Actuator

Considering the problems of total disturbances, i.e., higher harmonics, model uncertainties and external excitations in a practical vibration control system, a compound vibration suppression method is proposed for an all-clamped plate, which combines sliding mode control (SMC) with reduced-order extended state observer (RESO). First, a state space model of the all-clamped plate with inertial actuator is established. Second, a RESO is designed to estimate the system state variables and total disturbances in real time. In addition, the total disturbances can further be attenuated by RESO through a feedforward compensation part. Third, a sliding mode controller based on the estimation values is designed for a vibration control system. The Lyapunov stability theorem is further applied to prove the stability of the whole closed-loop vibration control system with the proposed controller. Finally, vibration control experiment equipment is built based on the NI-PCIe acquisition card, inertial actuator and acceleration sensor to verify the vibration suppression performances of the proposed method. The experimental results show that the amplitude value of vibration has been reduced by 75.2% with the proposed method, while the amplitude value is reduced by 54.5% with the traditional sliding mode control method based on an extended state observer (SMC-ESO). The comparative experimental results illustrate that the proposed method has excellent anti-disturbance and vibration suppression performances.

New Algorithm and Experiments for Helicopter Active Control of Structural Response

Active control of structural response on helicopter fuselages is an effective method for helicopter vibration control, but the existing algorithms for the method may cause the vibration control to fail or even diverge in the presence of large modeling errors in the control system and/or with time-varying excitation parameters. To effectively solve the problem, a frequency response function updating-harmonic identification algorithm is proposed and has been experimentally verified by using an experimental system of active control of structural response on a helicopter fuselage model structure with piezoelectric-stack-actuator-driven gearbox struts in this paper. Active vibration control experiments have been carried out by using the proposed algorithm and an electromagnetic exciter to excite the model structure. The experimental results show that the active control of structural response with the proposed algorithm can achieve effective, adaptive, and fast control effects in the presence of large phase modeling errors of frequency response functions and when changing the amplitude, phase, and frequency of exciting loads, and also show that the proposed algorithm has much better control effect and performance than the existing algorithm without frequency response function updating.

Active Vibration Control of Helicopter Maneuvering Flight Using Feedforward-Robust Hybrid Control Based on Reference Signal Reconstruction

Current control laws for active control of helicopter structural vibration are designed for steady-state flight conditions, while the vibration response of maneuvering flight has not been taken into consideration yet. In order to obtain full-time vibration suppression capability, the authors propose a filtered least mean square-mixed sensitivity robust control method based on reference signal reconstruction (LMS-MSRC), driving piezoelectric stack actuators to suppress helicopter structural vibration response in maneuvering flight. When feedback controller designed by H ∞ theory is implemented, active damping is added on the secondary path to weaken the adverse effects of its sudden changes in maneuvering flight state. Furthermore, a reference signal reconstruction scheme is given concerning equivalent secondary path. In addition, the reconstruction accuracy, the convergence speed, stability, and global validity of the hybrid controller are analysed. Compared with multichannel Fx-LMS, numerical simulations of LMS-MSRC for vibration suppression are undertaken with a helicopter simplified finite element model under several typical flight conditions. Further experiments of real-time free-free beam vibration control are performed, driven by a stacked piezoelectric actuator. The instantaneous overshoot of measured response is 42% less than the peak value and its attenuation reaches 85% within 2.5 s. Numerical and experimental results reveal that the proposed algorithm is practical for suppressing transient disturbance and multifrequency helicopter vibration response during maneuvering flight with faster convergence speed and better robustness.

Reinforcement learning vibration control for a flexible hinged plate

A reinforcement learning (RL) vibration control method for a flexible hinged plate is developed, including combined bending and torsional vibrations. The experimental setup is constructed. Two laser displacement sensors are used as detection sensors, and two-channel piezoelectric actuators are used to suppress both bending and torsional vibrations simultaneously. A method combining finite element modeling (FEM) and experimental identification is applied to obtain an accurate model of the system. The obtained model is constructed as an RL environment, and a deep deterministic policy gradient (DDPG) RL algorithm based on the priority experience replay (PER) is designed to train modal controllers. The RL modal controllers were transferred to the real experimental system by using the parameter transfer method, and the vibration control experiments were conducted by combining the bending and torsional vibration control method. Simulation and experimental results demonstrate that the controller trained by the proposed deep RL algorithm has better control effects compared with PD control, especially for small amplitude vibration.

Analysis of the Vibration Suppression of Double-Beam System via Nonlinear Switching Piezoelectric Network

In this paper, a method to suppress the vibration of a double-beam system with nonlinear synchronized switch damping on the inductor via a network (SSDI-net) is proposed. Unlike the classical linear piezoelectric shunt damping, SSDI-net is a nonlinear piezoelectric damping. A double-beam system with SSDI-net was simplified to a lumped parameter electromechanical coupling model and analyzed by using the multi-harmonic balance method, at first with alternating frequency–time techniques (MHBM/AFT). Then, a new lower-power autonomous switching control circuit board was designed, based on SSD technique, and vibration control experiments using a double-beam system with an SSDI network are conducted, to verify the validity of the proposed analysis method and its calculation results. The nonlinear switching piezoelectric network proposed in this article can increase the voltage inversion factor. Furthermore, future applications of this switching piezoelectric network technology in the vibration suppression of bladed-disk structures in aero engines can reduce the number of switches by at least half and obtain almost the same damping effect.

Novel Sliding Mode Vibration Controller With Simple Model-Free Design and Compensation for Actuator’s Uncertainty

This study proposes an active vibration control method with a simple design process without using a plant model. The proposed method is robust against the actuator’s parameter uncertainty. To realize model-free control of the controlled object, a virtual structure represented by a single-degree-of-freedom system is inserted between the controlled object and the actuator. A controller, which compensates for the uncertainties of the actuator’s parameters, is designed using the sliding mode control theory. By designing a controller using a model composed of the virtual structure and the actuator, model-free design can be easily performed with few design variables. After the virtual structure is introduced, the controller can be designed using the same process as a traditional model-based control theory. An advantage of the sliding mode control system is it can provide high robustness against the uncertainty in the actuator’s parameters. The robustness to the actuator’s uncertainty and vibration suppression performance of the proposed method are verified by controlling a two-degree-of-freedom time-varying system. Finally, the applicability of the proposed method to an actual mechanical system is confirmed by vibration control experiments.

Radial basis function neural network vibration control of a flexible planar parallel manipulator based on acceleration feedback

The self-excited vibration of flexible planar 3-RRR parallel manipulators is converted from the residual vibration after high-speed motion and is a resonance of the strongly coupled and nonlinear electromechanical system. This makes the active vibration control quite a challenging task. In this study, we attempt to adopt the radial basis function neural network control algorithm based on acceleration feedback for suppressing the self-excited vibration and guarantee its position accuracy. The stability of the controlled system is proved by the Lyapunov concept. Self-excited vibration control experiments are conducted near the singular region. Experimental results demonstrate the effectiveness of our adopted controller.

Vibration Modelling and Control Experiments for a Thin-Walled Cylindrical Rotor with Piezo Patch Actuation and Sensing

This paper describes a dynamic model formulation and control experiments concerning the vibration behaviour of a thin-walled cylindrical rotor with internal piezoelectric patch transducers. Model development, validation and controller design procedures were undertaken for an experimental rotordynamic system comprising a tubular steel rotor (length 0.8 m, diameter 0.166 m and wall-thickness 3.06 mm) supported by two radial active magnetic bearings. Analytical solutions for mode shapes and natural frequencies for free vibration were first derived using a shell theory model, and these used to construct a speed-dependent parametric model for the rotor structure, including piezo patch actuators and sensors. The results confirm that the developed shell theory model can accurately capture the rotating frame dynamics and accounts correctly for frequency splitting from Coriolis effects. The model is also shown to be suitable for active controller design and optimization. Model-based H2 feedback control using the rotor-mounted actuators and sensors is shown to achieve vibration suppression of targeted flexural modes, both with and without rotation.

Multidimensional System Identification and Active Vibration Control of a Piezoelectric-Based Sting System Used in Wind Tunnel

In wind tunnel tests, the cantilever sting is usually used to support aircraft models because of its simple structure and low aerodynamic interference. However, in some special conditions, big-amplitude and low-frequency vibration would occur easily on the model not only in the pitch direction but also in the yaw direction, resulting in inaccurate data and even damage of the supporting structure. In this paper, aiming at suppressing the vibration in pitch and yaw plane, a multidimensional system identification and active vibration control system on the basis of piezoelectric actuators is established. A vibration monitoring method based on the strain-displacement transformation (SDT) matrix is proposed, which can transform strain signals into vibration displacements. The system identification based on chirp-Z transform (CZT) is applied to improve the adaptability and precision of the building process for the system model. After that, the hardware platform as well as the software control system based on the classical proportional-derivative (PD) algorithm is built. A series of experiments are carried out, and the results show the exactness of the vibration monitoring method. The system identification process is completed, and the controller is designed. Vibration control experiments verify the effectiveness of the controller, and the results indicate that vibrations in pitch and yaw directions are attenuated apparently. The spectrum power is reduced over 14.8 dB/Hz, which prove that the multidimensional identification and active vibration control system has the capability to decline vibration from different directions.

Experimental validation of vibration control in membrane structures using dielectric elastomer actuators in a vacuum environment

A vibration suppression technique for lightweight and flexible membrane structures is proposed using smart structure technology with a dielectric elastomer actuator (DEA). DEA, which is a lightweight flexible polynomial material with a large deformation and high response time, can easily be applied to membrane structures for vibration suppression over a wide frequency range. Herein, active vibration control for membrane structures with DEA is examined. A non-contact excitation system with a high-power Nd:YAG pulsed laser precisely measures the vibration responses of membrane structures. A laminated DEA is fabricated and attached to the membrane surface, generating a highly reproducible ideal impulse excitation. Then a digital control system is constructed with the laser excitation system. To demonstrate the effectiveness of the proposed method, vibration control experiments are conducted using a controller designed by H∞ control theory with the identified membrane model in both atmospheric and vacuum environments.

Vibration Control of Tie Rod Rotors With Optimization of Unbalanced Force and Unbalanced Moment

This paper proposes a method for optimizing unbalanced force and unbalanced moment of the multistage disk based on sequence quadratic program algorithm to solve the vibration problem of gas turbine tie rod rotor. This method guides the assembly phase of the multistage disks. The influence of unbalanced force and unbalanced moment on the vibration of the tie rod rotor are analyzed based on the characteristics of rotor structure and assembly process. A dynamic model of the unbalanced force and unbalanced moment of the tie rod rotor is established. The sequence quadratic program algorithm is used to optimize multi-dimension of unbalanced force and moment, so the global optimal solution can be obtained. In order to verify the effectiveness of the optimization method proposed in this paper, vibration control experiments are carried out for traditional tie rod rotor and gas turbine tie rod rotor structure. The results show that both unbalanced force optimization and unbalanced moment optimization can control the tie rod rotor vibration effectively, and unbalanced moment optimization is better. Unbalanced moment optimization is used to perform constant speed and speed-up experiment on the gas turbine tie rod rotor structure. At 1200r/min, the maximum vibration reduction of the system is 76.68%. And the vibration has a decrease of 43.3% at the first-order critical speed. The proposed method in this paper can be used not only for the guidance of tie rod rotor assembly of gas turbine, but also for the vibration control during operation.