Semi-active Control Research Articles

Study on semi-active damping control strategies to improve dynamic behavior of high-speed trains subject to strong crosswinds

The aerodynamic loads on high-speed trains (HSTs) increase as the running speed increases. Particularly, strong crosswinds can significantly increase these loads and generate a safety risk to trains. This paper focuses on the application of semi-active control strategies based on secondary lateral suspension for HST operating in crosswinds, aiming to enhance the running safety of HST. First, a vehicle nonlinear dynamics model with 50 degrees of freedom (DOFs) is established. The aerodynamic loads caused by crosswinds are simulated using Simiu wind spectra, and the track irregularities are acquired through field tests of the high-speed railway line. Second, a semi-active control model is set up using Matlab/Simulink to replace the secondary lateral damper, and the co-simulation for vehicle dynamics and semi-active control is undertaken. Then, the vibration characteristic analysis of the vehicle system caused by aerodynamic loads under crosswind conditions is conducted in both time and frequency domains, while a conventional semi-active control strategy is employed to attenuate the vibrations. Moreover, a single coefficient mixed skyhook and groundhook control strategy (SMSG) regulated by a single mixing coefficient β, and mixed skyhook and acceleration driven damper control strategy (MSA) is proposed. The simulation results demonstrate that the proposed mixed skyhook and groundhook control strategy not only enhances the running safety of the trains in crosswind environments by adjusting the mixing coefficients but also improves ride performance compared to passive suspensions. While the suggested mixed skyhook and ADD control strategy can apparently reduce the vibration of the carbody.

Long short-term memory-enhanced semi-active control of cable vibrations with a magnetorheological damper

Long short-term memory-enhanced semi-active control of cable vibrations with a magnetorheological damper

Modelling, Analysis and Validation of Hydraulic Self-Adaptive Bearings for Elevated Floating Bridges.

Conventional floating bridge systems used during emergency repairs, such as during wartime or after natural disasters, typically rely on passive rubber bearings or semi-active control systems. These methods often limit traffic speed, stability, and safety under dynamic conditions, including varying vehicle loads and fluctuating water levels. To address these challenges, this study proposes a novel Hydraulic Self-Adaptive Bearing System (HABS). The system integrates real-time position closed-loop control and a flexible support compensation method to enhance stability and adaptability to environmental changes. A modified three-variable controller is introduced to optimise load response, while a multi-state observer control strategy effectively reduces vibrations and improves traffic smoothness. A 1:15 scale prototype was constructed, and a co-simulation model combining MATLAB/Simulink and MSC Adams was developed to simulate various operational conditions. Results from both experiments and simulations demonstrate the HABS's ability to adapt to varying loads and environmental disturbances, achieving a 72% reduction in displacement and a 54% reduction in acceleration. These improvements enhance traffic speed, stability, and safety, making the system a promising solution for emergency and floating bridges, providing superior performance under challenging and dynamic conditions.

Magnetostrictive Vibration Suppression via Integration of Current Amplification Negative Capacitor and Current Inversion Semi-Active Control Circuit

When attempting to suppress structural vibrations employing a magnetostrictive transducer, owing to the control force is generated from current, a larger amplification of the current entails superior control performance. The semi-active control theory uses the synchronized switching damping (SSD) technique for structural vibration suppression while requiring a minimal energy supply. However, the absence of external energy input limits the current amplification performance. To address this limitation, this study proposes a novel method that combines semi-active vibration suppression method with negative capacitance to improve the current amplification performance. The proposed circuit switches the circuit status between shunt, inductor-capacitor (LC) electrical oscillation, and negative capacitance circuits. A mathematical model was employed to analyze the current operation, suppression performance, and robustness of the proposed circuit. Further, machine learning and kernel regression model were employed to predict the optimal control force gain. Validation experiments conducted on a 10-bay truss structure identical to the simulation model show that the experimental results align with the simulation predictions. The vibration suppression rates of the proposed method under single-mode and multiple-mode vibrations reached 85.8% and 78.3%, respectively, which are 2.64 and 1.89 times higher than those achieved by conventional methods.

Research on intelligent semi-active control algorithms and seismic reliability based on machine learning

Aiming to address the shortcomings of existing semi-active control algorithms with poor robustness and the limited generalization ability of current evaluation methods based on deterministic analysis, a novel approach based on probability density evolution is proposed. This method is designed to assess the seismic reliability, enabling a more comprehensive evaluation of the control effectiveness of aqueduct structures. Building upon this, an intelligent semi-active control algorithm leveraging machine learning is introduced. The algorithm is further validated through engineering case studies to investigate semi-active control strategies in response to random seismic events. The results show that the seismic reliability of the machine learning-based semi-active control algorithm is significantly higher than that of the uncontrolled state for the same failure threshold under random seismic effects.

Semi-Active Vibration Control for Wind Turbines: A Variable Tuned Mass Damper Approach Utilizing 1st Modal and 3P Tuning

Vibration in wind turbine towers poses a significant threat to the service life and structural integrity of wind turbines. Dampers have been identified as a pivotal strategy for alleviating such vibrations. Despite this, the dynamic behavior of large-scale offshore wind turbines is frequently swayed by wind shear, the tower shadow effect, and the Rotor-Nacelle Assembly (RNA) control system, typically manifesting as responses to the blade passing frequency (3P). To mitigate these vibrations, this study introduces a 3P tuning method for tuned mass dampers (TMDs), alongside a sophisticated design approach that targets optimal frequency and damping ratios. The integration of a semi-active variable-tuned mass damper (SA-V-TMD) offers a dual-mode control solution: The “3P tuning mode” adeptly manages vibrations across a spectrum of operating conditions, while the “1st modal frequency tuning mode” stabilizes the structure during parked states. Simulations substantiate the 3P tuning method’s enhanced efficacy over standard methods under operational conditions. Furthermore, the SA-V-TMD demonstrates superior effectiveness and stability in comparison to traditional TMDs, underscoring its potential as a preeminent solution in wind turbine vibration management.

Dynamic reliability-based assessment for the seismic performance of semi-actively base-isolated buildings with hydraulic dampers

Seismic base isolation faces the challenge of the large displacement demands for the isolators in case of long-period ground motions. Semi-active control has the potential to mitigate the risk against such extreme scenarios and therefore increase the seismic reliability of base-isolated structures. However, the superstructural nonlinearity and the time delay in the control system are always neglected in related studies. Such a knowledge gap may overestimate the benefit of semi-active control in enhancing the seismic reliability of base-isolated buildings. This study explores the seismic reliability of semi-actively base-isolated buildings with realistic considerations of the superstructural nonlinearity and the time delay in a practical hydraulic control system in a fully probabilistic framework. It features the use of the probability density evolution method (PDEM) and the development of a MATLAB-OpenSees interaction technique. The reliability of the semi-actively isolated structure and its passive counterpart are compared, highlighting the effects of nonlinearity and time delay. The results show the superstructural nonlinearity and the inevitable time delay in a practical hydraulic control system may significantly degrade the control performance of semi-actively base-isolated buildings, potentially leading to higher failure probabilities than passive buildings.

Three-Axis Vibration Isolation of a Full-Scale Magnetorheological Seat Suspension.

This study examines the three-axis vibration isolation capabilities of a full-scale magnetorheological (MR) seat suspension system utilizing experimental methods to assess performance under both single-axis and simultaneous three-axis input conditions. To achieve this, a semi-active MR seat damper was designed and manufactured to address excitations in all three axes. The damper effectiveness was tested experimentally for axial and lateral motions, focusing on dynamic stiffness and loss factor using an MTS machine. Prior to creating the full-scale MR seat suspension, a scaled-down version at one-third size was developed to verify the damper's ability to effectively reduce vibrations in response to practical excitation levels. Additionally, a narrow-band frequency-shaped semi-active control (NFSSC) algorithm was developed to optimize vibration suppression. Ultimately, a full-scale MR seat suspension was assembled and tested with a 50th percentile male dummy, and comprehensive three-axis vibration isolation tests were conducted on a hydraulic multi-axis simulation table (MAST) for both individual inputs over a frequency range up to 200 Hz and for simultaneous multi-directional inputs. The experimental results demonstrated the effectiveness of the full-scale MR seat suspension in reducing seat vibrations.

Latching control for pendulum tuned mass damper: Theoretical analysis and proof-of-concept experiment

Long-period vibrations are very common in various flexible structures, such as high-rise buildings and floating structures. Inspired by latching-based phase optimization in wave energy converters (WECs), a latching control mechanism is applied to realize long-period vibration control. Based on pendulum tuned mass dampers which are a traditional type of vibration control device, an innovative pendulum latched mass damper (PLMD) is proposed, fabricated, and investigated for the first time in this study. First, the concept of PLMD is introduced, and the theoretical model is established. Second, the mechanism and semi-active control strategies for the proposed PLMD are designed. Third, an innovative bench-scale PLMD system is designed and fabricated, wherein the latching control is achieved by using a permanent magnet (PM) brake. Proof-of-concept experiments and numerical simulations are conducted to examine the characteristics, feasibility, and effectiveness of the proposed PLMD. The effects of different latching strategies and time delay are particularly discussed. The proposed latching control mechanism will offer a new and promising solution to remarkably advance long-period vibration control and adaptive-frequency vibration control for various engineering structures.

Research on the sensing properties and vibration reduction performance of self-sensing self-tuning magnetic fluid damper

Abstract The semi-active control damping system has gained popularity due to its quick response time and versatility. However, external sensors are susceptible to environmental interference, affecting system reliability and increasing complexity and maintenance costs, restricting their use. To address this, a self-sensing self-tuning magnetic fluid damper (SSMFD) is proposed. The vibration-measuring induction coil is wound on the damper to sense the magnetic fluid vibration information in real time, and the vibration signal is communicated to the self-tuning control circuit. The control circuit calculates and determines the dominant frequency of structural vibration, then outputs the relevant current signal to set the damper’s natural frequency to track the excitation frequency, resulting in self-tuning vibration reduction. First, the self-sensing unit’s output induced electromotive force model is created, followed by an expression of the damper’s natural frequency, indicating that the self-sensing unit can achieve self-tuning vibration reduction by tracking the excitation frequency. The multi-field coupling simulation model of the magnetic fluid damper is generated, and the induction coil coupling mode and damper excitation angle are defined to obtain the maximum induced voltage. Finally, an experimental platform was developed to assess the damper’s self-sensing and self-tuning vibration reduction performance. The experimental results show that the proposed SSMFD performs well, making it a feasible solution for achieving self-sensing and self-tuning vibration reduction.

Dynamic Modeling of Suspension with Air Spring

The present work aims to model a ¼ vehicle semi-active suspension, using a combination of air spring and magneto-rheological damper. The modeling of the magneto-rheological damper will be based on the Wang model, which will be calibrated through experimental tests. The air spring model will be employed to compare performance between discrete mechanical models and the thermodynamic model. Various semi-active control strategies, such as bang-bang type skyhook/groundhook and PID, will be explored for comparison with existing selective passive systems on the market. The study of the air suspension with magneto-rheological damper will be evaluated from the perspective of comfort and drivability, following standardized parameters (ISO 2631:1978).

Design and experimental study of a semi-active shear-mode vibration absorber using magnetorheological elastomer

This paper presents the design process of a magnetorheological elastomer (MRE) absorber with a shear symmetric structure based on detailed simulation and experiments. First, the MRE materials and dimensional parameters of the MRE absorber are determined, and magnetic field simulation is performed to analyze the magnetic induction performance in the working area. Then, a dynamic simulation model is constructed to analyze the frequency response characteristics of a semi-active vibration system. Finally, a vibration experimental platform is built to test the response performance of the shear-mode MRE absorber. The experimental results showed that the stiffness of the MRE absorber can be effectively adjusted by current. When the applied current changes from 0.5 to 2 A, a vibration reduction frequency band of 8.91 to 14.19 Hz will be formed. The closer the natural frequency in this frequency band is to the external excitation frequency, the better the vibration reduction effect, which verifies the effectiveness of semi-active vibration control for the primary system. These results validate the rationality and feasibility of the semi-active MRE absorber, providing a good reference for the design of MRE absorbers.

Comparative Study of Semi-Active Control Effectiveness of Structures on Soft Soil Using MR Damper: Shaking Table Investigation

The effect of soil-structure interaction (SSI) cannot be neglected in semi-active vibration control of structures located on soft soil. To investigate the mitigating effect of magnetorheological (MR) damper on the semi-active control of structures considering the SSI, shaking table tests were conducted to evaluate the performance of the MR damper-based semi-active control system for structures on soft soil. In addition to a novel fuzzy control method based on online learning deep neural network (OL-DFNN), various control strategies, including passive OFF, passive ON, ON–OFF and deep neural network fuzzy control (DFNN) were systematically evaluated. The test results showed that the OL-DFNN control method exhibited superior adaptability to varying ground motion and structural dynamic characteristics compared to the other control methods. In particular, the OL-DFNN controller effectively mitigated the peak displacement and root mean square displacement, outperforming the passive OFF, passive ON, ON–OFF and DFNN control strategies. The test results highlight the effectiveness of the OL-DFNN control method in addressing the challenges posed by dynamic and time-varying characteristics in structural vibration control systems considering SSI.

Semi-Active Suspension Control Strategy Based on Negative Stiffness Characteristics

This paper investigates the potential of negative stiffness suspensions for enhanced vehicle vibration isolation. By analyzing and improving traditional control algorithms, we propose and experimentally validate novel skyhook, groundhook, and hybrid control strategies for suspensions with negative stiffness characteristics. We establish pavement models, incorporate negative stiffness into suspension modeling, and develop a performance evaluation index. Our research identifies shortcomings of classical semi-active control algorithms and introduces a new band selector to combine improved control methods. Simulation results demonstrate that the proposed semi-active suspension control strategy based on negative stiffness effectively reduces body vibration and enhances vehicle ride performance.

Semi-active vibration control via a magnetorheological damper and active disturbance rejection control

This work provides an alternative for the semi-active vibration control problem via state feedback plus an active disturbance rejection control (K-ADRC) for a multistory building structure equipped with one magnetorheological damper (MRD) located between the ground and the first story. This control law introduces a disturbance observer (DOB) to estimate the total disturbance in real time, produced by the earthquake perturbation, unmodeled dynamics, and parametric uncertainties, and then cancel their effect using a part of the control signal. Moreover, using a diffeomorphism, the K-ADRC provides a proportional derivative (PD) controller designed to improve internal stability. A prominent feature of the active disturbance rejection control (ADRC) algorithm is that the value of the DOB gain is selected according to the system bandwidth. The stability of the system is verified via Lyapunov analysis. Moreover, the building structure model and the MRD are accomplished by incorporating a nonlinearity state that represents the hysteresis effect to perform real behavior in addition to assuming that acceleration is the only available measurement of building structures. Thus, integral filters are provided based on the appropriate cut-off frequency to estimate displacement and velocity, avoiding bias, offset, and phase shifts. Experimental results from a reduced-scale two-story building prototype demonstrate that the proposed K-ADRC is promising for real applications, and it has better performance than the state feedback (K) and the linear quadratic regulator (LQR) control techniques.

Optimal replicator dynamic controller for semi active control of long span cable stayed bridge with considering special variability of seismic excitations

Cable-stayed bridges are lifeline infrastructures. However, due to their design and structural characteristics, they are sensitive to the vibrations. Thus, vibration control in these structures is essential. Semi-active control systems have gained significant attention due to their high performance and adaptability. However, the implementation of these systems has always faced serious challenges particularly when it comes to developing appropriate control algorithms because semi active devices have complex and non-linear characteristics. Inspired by evolutionary game theory, the author utilizes the replicator dynamic controller concept to optimize the performance of MR dampers to improve the vibration reduction of cable-stayed bridges. Two key parameters in the proposed control methodologies using replicator dynamics are the total population (total available resources or the sum of actuator forces) and the growth rate. Instead of using the sensitivity analysis that has been done in previous studies for vibration reduction of highway bridges using a replicator controller, the author used an evolutionary algorithm named the nondominated sorting genetic algorithm (NSGA-II) to create an optimal replicator dynamic controller for more effective vibration reduction. The proposed methodology is evaluated through its numerical application to a second-generation benchmark example based on the Bill Emerson Memorial Bridge, which considers a more realistic behavior of the cable-stayed bridge by accounting for multiple support excitations. The study indicates that the optimal replicator dynamic controller improves the vibration reduction performance of MR dampers. Specifically, deck displacement is reduced by 46 % compared to passive control system and shear forces at the tower base are reduced by 33 % compared to active control systems for the El Centro earthquake. The results indicate that the proposed Replicator Dynamic Controller optimized through NSGA-II provides a robust and effective solution for improving seismic resilience of cable-stayed bridges.

Intelligent vibration control of tensile cable based on deep reinforcement learning

Vibration of tensile cables commonly occurs in the engineering structures such as cable-stayed bridges, which may have negative effect on the driving comfort and safety, and further lead to the fatigue problems of the structure. This paper proposes a semi-active control strategy based on deep reinforcement learning and magneto-rheological (MR) damper, for the vibration control of tensile cables, and the corresponding algorithm have been developed. Through the interaction with the cable-damper system, the intelligent agent can evaluate every possible control parameter and achieve an effective control policy. Then, according to the real-time vibration state, the agent would determine an action current for the MR damper and thus change the damping coefficient of the damper, further make influences on the vibrating cable. Basically, the proposed strategy realizes the model-free semi-active control of cable vibrations. To validate the effectiveness of the proposed semi-active control strategy, a scale model test has been conducted, where the test cases of passive and semi-active control strategies are carried out and compared. Results show that, the semi-active control shows a prior performance in vibration reduction compared to the passive control strategy, with regard to the vibration profile, the vibration energy, as well as the energy dissipation of MR damper.

Design of semi-active suspension control method based on an enhanced inverse model for nonlinear magnetorheological dampers

Design of semi-active suspension control method based on an enhanced inverse model for nonlinear magnetorheological dampers

Magnetorheological damper parameter identification and its application in semi-active control of power equipment

In recent years, magnetorheological dampers (MRD) have played a significant role in vibration control in various fields such as vehicles, military, building structures, etc. However, the mechanical model of MRD is very complex due to its hysteresis, which makes it difficult to identify the model’s parameters. In addition to experimental data, under the condition of no other prior knowledge, eight unknown parameters of the Bouc-Wen model are identified in this study based on the particle swarm optimization (PSO) algorithm. According to the trend of parameter variation with current, fitting research is conducted, and the variation law of parameters with current is summarized. Based on the identified parameters, the MRD’s output force is predicted under any current other than the experimental current. Subsequently, the application of MRD in semi-active control of power equipment is performed out, and proposed Simulink calculation programs for single-stage and two-stage vibration control systems are built. Then, a comparative study with passive and active control is conducted. In this paper, linear quadratic regulator (LQR) control is adopted for the active control, and the controller’s parameters are optimized based on the PSO algorithm. The results show that the adopted semi-active control can significantly reduce the transmitted force from power equipment to the foundation and can effectively mitigate the disturbance of power equipment to the environment. This study offers important guidance for the vibration control of MRD in industrial engineering.

Research on dynamic performance and mechanical model of a novel magnetorheological shear thickening damper with adaptive variable damping gap

Abstract Magnetorheological shear thickening fluid (MRSTF) is an intelligent composite material, which shows considerable potential in semi-active vibration control. However, the current research is mostly limited to the study of the rheological properties of materials, and there is still a lack of damper structures that can effectively utilize the dual-control characteristics of MRSTF. In this paper, a novel damper structure with adaptive adjustable damping gap length is proposed. Its unique design integrates an adaptive internal damping gap that changes with the movement of the piston and an external gap controlled by the magnetic field, providing a relatively wide range of current-controlled damping force and reliable adaptive adjustment capabilities. Based on the M-S shear stress constitutive model and structural characteristics, the mechanical model is derived from the force balance of the micro-element, and verified by performance test and curve fitting. The effectiveness of the new damper structure proposed in this paper is verified by dynamic performance test. The results show that the damper has a wide range of current controlled damping force at low speed and reliable adaptive adjustment capability at high speed. Finally, the accuracy and universality of the modified mechanical model of damper are verified by curve fitting method. All these studies can offer an effective guidance for further application of MRSTF in the field of semi-active vibration control.