Semi-active Control Strategy Research Articles

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.

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.

Technical study of magnetorheological semi-active suspension control strategy for vehicles based on reinforcement learning

The suspension system is an important part of the car, the main function is to alleviate the road surface does not level brought about by the shake, to ensure that the vehicle driving smoothness and comfort, so as to improve the vehicle handling performance and safety, improve the vehicle to reduce the vibration performance more and more become a hot topic in the industry. Among them, semi-active suspension is a popular suspension system. This paper explains the significance and classification of the role of the suspension, and gives a relevant introduction to the magnetorheological fluid, on the basis of which it combines the domestic and international research results, looks forward to the development trend of the semi-active suspension of the vehicle, analyzes the advantages and shortcomings of four important semi-active suspension control strategies, and finally introduces the reinforcement learning and combines the reinforcement learning with the existing control strategies of the semi-active suspension, and designs a reliable reward function to enhance the suspension's damping performance by taking into account the multifaceted driving factors. The reward function to enhance the damping ability of the suspension by considering multiple driving factors, which can provide a reference for further research on the control of magnetorheological semi-active suspensions for vehicles.

Experimental test and analysis of impact suppression for hydraulic-driven leg using a new MR damper with multi-channels

When hydraulic-legged robots move under high loads on irregular ground, they are vulnerable to ground impacts. Vibration affects the motion performance of the robot and damages its mechanical structure. This study aims to improve the properties of vibration absorption and impact resistance of hydraulic-legged robots. Because the traditional MR damper (MRD) has small output in finite volume, a novel MRD with a multistage flow channel (MFC-MRD) can output a large damping force designed. First, an MRD prototype was designed for a mechanical leg’s driving joint. Subsequently, the system is analyzed theoretically, and a semi-active control strategy is designed and simulated. Finally, the vibration and impact resistance of the prototype were tested. The experimental results show that in the signal tracking experiment, the maximum overshoot under semi-active control was reduced by 53.0%, and the settling time was reduced by 76.9% compared with the passive control. The impact test reduced the maximum displacement fluctuation by 41.09%, and the buffer time is only 0.24 s.

Analysis of the influence of mechanical vibration control strategy on structural safety

The vibration of rotating machinery has always been the focus of attention in the engineering field, because it directly affects the performance, life and safety of equipment. In this paper, the influence of vibration control strategy of rotating machinery on structural safety is deeply studied, aiming at providing scientific basis for optimizing vibration control scheme. It is found that the network identification accuracy of vibration signals of rotating machinery is above 96% under different vibration conditions by the vibration control method designed in this paper, which is higher than the traditional control method. Active vibration control strategy has high accuracy and real-time, but it challenges the cost and complexity of the system. Passive vibration control strategy is excellent in specific frequency vibration suppression, but there are some limitations in multimode vibration; Semi-active vibration control strategy has both active and passive advantages and strong adaptability, but it needs complex control algorithm. These efforts will provide useful reference for the development of vibration control field of rotating machinery and the safety improvement of engineering structures.

Semi-Active Groundhook Control of Offshore Tension Leg Platforms Using Tuned Mass Damper With Optimized Parameters and Magneto-Rheological Damper Under Multiple Hazards

Abstract The purpose of the current study is to recommend an offshore tension leg platform (TLP) semi-active control system to lessen vibrations caused by various risks, such as the wind load and regular and irregular waves. State-of-the-art indicates that there has not been much study on semi-active management of offshore TLPs exposed to numerous hazards while taking into account system nonlinearities and employing a control method that is resilient to uncertainty. An augmented velocity–displacement-based groundhook (AVDB-GH) semi-active control scheme using magneto-rheological (MR) dampers, which is an improvement over the displacement-based groundhook (DB-GH) control algorithm, is proposed. The proposed controller uses a semi-active tuned mass damper (SATMD) consisting of a passive tuned mass damper (TMD) and two semi-active MR dampers as the control devices. Constrained nonlinear optimization is used to determine the SATMD's optimized parameters in order to produce the best control performance. A significant reduction in surge response of TLP is observed both in the time domain and the frequency domain. Compared to the SATMD using the usual DB-GH algorithm, the suggested control strategy more successfully decreases the key response variables—deck displacement, power spectral density, and acceleration. The effectiveness of the controller is better for regular waves than for irregular waves and wind forces. Because the performance of the controller is unaffected by changes in the mass and stiffness of the TLP, the controller can be regarded as robust.

Dynamic Performance Analysis of Semiactive Vehicle ISD Suspension Based on the Power-Driven-Damper Strategy

In this paper, the vehicle ISD (inerter-spring-damper) suspension and power-driven-damper control strategy are combined to the suspension design, and the power-driven-damper semiactive ISD suspension is proposed. The dynamic models of the passive suspension S1 and two semiactive ISD suspensions S2 and S3 are established. Based on the port-controlled Hamiltonian theory, the power-driven-damper semiactive control strategy is designed by analyzing the power transfer of suspension S3. Then, the parameters of the two models are optimized by the particle swarm optimization algorithm, and the optimization results show that the suspension S3 has better performance. The influence of the semiactive damping coefficient, the spring stiffness, and the inertance on the vibration suppression performance is investigated based on the suspension S3. The effect of parameter perturbation on power-driven-damper semiactive vehicle ISD suspension illustrates that the designed semiactive vehicle ISD suspension has better ride comfort in a wider range frequency and good robust performance.

Semiactive Control of Nonlinear Parametric Vibration of Super‐Long Stay Cable in Cable‐Stayed Bridge Installed with Magnetorheological Fluid Damper

As the stay cables of cable‐stayed bridges become longer, parametric resonance with a large amplitude is more easily triggered, which becomes a vibration hazard of super‐long stay cables. An increasing number of practical applications of vibration mitigation on stay cables demonstrate that vibration control strategies can effectively facilitate hazard mitigation and improve cable‐stayed bridge reliability and service life. This study proposes a semiactive control approach to reduce the parametric vibration of super‐long stay cables in cable‐stayed bridges installed with magnetorheological fluid damper (MRFD). First, using the cable’s gravity sag curve equation, an equation governing the combined stay cable‐bridge deck‐damper control system was established to consider the effect of the chordwise force of cable gravity. Subsequently, a targeted LQR‐based optimal active control law is proposed to provide the target control force in the semiactive control. The parametric influences on the performance of the LQR‐based optimal active control were analysed to provide insight into the proposed control strategy. Since the semiactive control could achieve almost the same control efficacy of the targeted optimal active control, a semiactive control strategy employing MRFD is proposed to mitigate the parametric vibration of a super‐long stay cable. Based on the proposed semiactive control strategy, the system was attached with the MRFD of the longest cable, S36, in the designed prototype long cable‐stayed bridge. The efficacy of the established semiactive control system was also analysed. The analysis results confirm that the proposed semiactive control strategy and designed semiactive control system can perform similar to the LQR‐based optimal active control. The semiactive control system attached to the MRFD can mitigate the parametric vibration of super‐long stay cables in cable‐stayed bridge engineering practice.

Real-Time Integration of Identification and Semiactive Optimization Control for Mass Damper-Building Combined Systems under Known/Unknown Seismic Excitations

The integration of structural identification and vibration optimal control has been studied. Since the semiactive optimization vibrational control of civil structures needs to be implemented by massive control devices such as mass dampers, it is necessary to investigate the real-time integration of identification and semiactive optimization vibration control for mass damper-building combined systems. However, there is a lack of such studies in the literature. In this paper, a methodology is presented for real-time integration of identification and semiactive optimization vibration control of the mass damper-building combined system under known/unknown seismic excitations. For the combined system under known seismic excitations, the identification is implemented by the extended Kalman filter (EKF) using only partial structural acceleration responses. The identified structural state and parameters of mass damper-building systems are integrated in real time for the optimal control of systems by the linear-quadratic regulator (LQR) control algorithm and the Hrovat semiactive optimization control strategy via semiactive optimization mass dampers (SAMD). Then, it is extended to the scenario of unknown seismic excitations. The partially measured structural acceleration responses are absolute ones in this case, so the generalized extended Kalman filter with unknown input (GEKF-UI) developed by the authors is used to identify the structural input-state parameters of the mass dampers-building combined systems. The identification results are also integrated in real time for the semiactive optimization control of the combined system via SAMD. Two numerical simulation examples are used to test the proposed integration methods. It is shown that the proposed integration methods can reach almost the same optimal control effects as the conventional semiactive optimization control with known parameters of the mass damper-building combined systems under known/unknown seismic excitations.

Particle swarm optimized fuzzy proportional-integral-derivative controller-based transverse leaf spring active suspension for vibration control

The transverse leaf spring (TLS) suspensions are a promising option for van vehicles due to their high load-carrying capacity and excellent handling stability. However, its ride comfort remains a major challenge. This paper investigates and compares the effects of semi-active and active control strategies to enhance the ride comfort of TLS suspensions. Firstly, a four-degree-of-freedom (4-DOF) half-car model and a multi-body dynamics (MBD) model of the TLS suspensions are established. The MBD model has higher accuracy and can describe the medium and high frequency characteristics of the TLS suspensions, such as the suspension offset frequency and the frequency response function of the body vertical acceleration (BVA). Therefore, based on the MBD half-car model with TLS suspensions, this paper proposes an optimal fuzzy PID active control strategy considering the left and right suspension coupling. The optimization objectives are the BVA, the left and right suspensions dynamic deflection, and the left and right wheels dynamic displacement. The integral absolute error is used as the evaluation criterion. The left and right fuzzy PID controllers’ parameters are obtained through particle swarm optimization. Simulation results demonstrate that the particle swarm optimization fuzzy PID active control strategy effectively controls the low-frequency vibration of the TLS suspensions and suppresses the medium- and high-frequency vibration characteristics compared with the traditional skyhook semi-active control strategy. This technology provides a reference for improving the ride comfort of the TLS suspensions.

Robust predictive compensation control for lateral magnetorheological semi-active suspension of high-speed trains with time delay

ABSTRACT Aiming at reducing the effect of time delay on the control performance of magnetorheological (MR) damper semi-active suspension, a control strategy with strong robustness to time delay is investigated in this study, including the force controller of MR damper, the robust controller and the predictive compensator. The force controller of MR damper is built based on the hyperbolic tangent function; the robust controller is built based on the simplified model of car body lateral vibration and is designed by μ-synthesis method considering the effect of time delay; then the Smith predictive model and the lateral velocity predictor are designed, which form the predictive compensator of semi-active controller to reduce the effect of time delay. To validate the effectiveness of the proposed control strategy, several conventional semi-active controllers are designed as comparative objects. The simulation results show that the proposed semi-active control strategy can maintain good performance when time delay is in the range of 0–100 ms and has better robustness to time delay compared with the conventional control strategy.

Research on Two-Stage Semi-Active ISD Suspension Based on Improved Fuzzy Neural Network PID Control.

To better improve the ride comfort and handling stability of vehicles, a new two-stage ISD semi-active suspension structure is designed, which consists of the three elements, including an adjustable damper, spring, and inerter. Meanwhile, a new semi-active ISD suspension control strategy is proposed based on this structure. Firstly, the fuzzy neural network's initial parameters are optimized using the grey wolf optimization algorithm. Then, the fuzzy neural network with the optimal parameters is adjusted to the PID parameters. Finally, a 1/4 2-degree-of-freedom ISD semi-active suspension model is constructed in Matlab/Simulink, and the dynamics simulation is carried out for the three schemes using PID control, fuzzy neural network PID control, and improved fuzzy neural network PID control, respectively. The results show that compared with adopting PID control and fuzzy neural network PID control strategy, the vehicle body acceleration and tire dynamic loads are significantly reduced after using the grey wolf optimized fuzzy neural network PID control strategy, which shows that the control strategy proposed in this paper can significantly improve the vehicle smoothness and the stability of the handling.

Application of metal rubber for semi-active vibration control of mechanical transmission systems

This study proposes a novel semi-active vibration control technique for mechanical transmission systems. The backbone of current research technology is the adaptive stiffness and damping properties of metal rubber (MR) which plays the role of tuning to the vibrational system eigenmodes. The adaptive properties of MR material were proved by a previous study, but the present research investigates the effect of this feature on the structural response and designs an MR-based semi-active vibration controller for industrial application. For this purpose, the semi-active control strategy is created based on an optimal tuning using experimental harmonic test results. The control strategy is applied in practice using a linear actuator controlled by a double pole double throw (DPDT) relay, and National Instruments hardware and software for reading data and writing the control task. The isolator attachment position is defined through the analysis of eigenmode shapes that are predetermined by numerical simulation. A maximum isolation rate of 55.17% is measured near the vibration isolator position. It is observed that the isolation position has a prominent effect on structure vibration behavior where the elastic wave has been reduced in amplitude by passing the isolator position. The effectiveness of the MR-based semi-active control approach is eminent and its application for vibration isolation of commercial mechanical transmission systems could be studied in the future.

Experimental and Analytical Evaluation of an Acceleration-Based Semiactive Control Strategy for Automotive Suspension Systems with Magneto-Rheological Damper

<div>Most of the control strategies presented to date are based on either the velocities or displacement of the vehicle body and the wheel which are derived by filtering and converting the data from the accelerometer. This increases the computational load and therefore directly affects the performance of the semiactive suspension system. This study presents a control strategy purely based on the acceleration for semiactive control of vehicle suspension with a magneto-rheological MR damper. The effectiveness of the acceleration-based skyhook (ASH) control strategy is compared with the existing velocity-based skyhook (VSH) control strategy based on the vibration response of a single-degree-of-freedom (SDOF) system. The effectiveness of ASH is evaluated experimentally, and the reaction time is evaluated analytically. The experimental results revealed that the ASH reduces the peak displacement and peak acceleration of the mass under the free vibration test and also improves the settling time as compared to VSH. The amplitude of the displacement and acceleration was also found to be reduced under the forced vibration test with maximum improvement observed during high-frequency excitation. The reaction time of ASH was also found to be considerably lower than VSH. Therefore, it was learned that the proposed ASH performed better under high-frequency excitation than under lower-frequency excitation. Moreover, the lower reaction time of the ASH could improve the overall performance of the semiactive suspension system.</div>

A Versatile Semiactive Electrically Interconnected Suspension With Heave-Roll Vibration Decoupling Control

This paper develops a versatile electrically interconnected suspension (EIS) system with variable inertance and variable damping (VIVD) in the heave direction and variable stiffness (VS) in the roll direction for vehicles to improve ride comfort. The conventional hydraulicly interconnected suspensions have been utilized to improve ride comfort and prevent rollover, while such a hydraulic system results in more design complexity, maintenance, and cost. The EIS can achieve the suspension interconnection electrically and offer more design flexibility, energy efficiency, and faster system response. The proposed EIS comprises two electromagnetic dampers (EMDs), which are interconnected by an electrical network (EN) with controllable resistors, capacitors, and inductors, enabling the suspension to generate VIVD and VS characteristics in heave and roll, respectively. The system only requires energy for controlling electronic switches, which is low and efficient. Then, a decoupling semi-active control strategy based on <inline-formula><tex-math notation="LaTeX">${\mathbf{H}}_\infty $</tex-math></inline-formula> controller is proposed to mitigate the heave and roll vibration. Moreover, a half-car test rig is developed to evaluate the vibration control performance of the proposed EIS system by conducting a series of comprehensive tests. As a result, the EIS has a significant improvement in performance than a passive suspension. The versatile EIS has reduced the resonance by 13.0&#x0025; compared to non-versatile EIS. The proposed versatile EIS system has great potential in practical application.

Semi-Active Vibration Control of Seat Suspension Equipped with a Variable Equivalent Inertance-Variable Damping Device

The seat suspension has a significant influence on riding comfort in many practical applications, such as heavy duty vehicles, military vehicles, and high-speed crafts. This paper proposes a seat suspension equipped with a variable equivalent inertance-variable damping (VEI–VD) device and a novel semi-active vibration control strategy. The VEI–VD device can control its equivalent inertance and damping by controlling two external resistors in its electric circuit. Especially, the VEI part of the device can store and release vibration energy via the inside flywheel, which enables the seat suspension to have a four-quadrant controllable capability in the available force–velocity diagram, similar to an active system. First, the dynamic model of the VEI–VD device is built, and a prototype is developed and tested to identify the model parameters and verify its characteristics. Then, a semi-active vibration control method is proposed for the VEI–VD seat suspension. The control method uses a sliding mode controller to acquire the desired control force for reducing vibration; then, according to the desired force and system states, the VEI–VD device is tuned by a force-tracking scheme to generate a real force. In the numerical validation, the vibration transmissibility of VEI–VD seat suspension around its natural frequency is tested with different states. The effectiveness of force-tracking control strategies for different types of suspensions is verified. In the random excitation test, the root means square acceleration of the VEI–VD seat is reduced by 30.72% compared with a passive seat. The VEI–VD seat suspension shows great potential in applications.

Seismic reliability research of continuous girder bridge considering fault-tolerant semi-active control

Continuous girder bridge is one of the most widely used bridge types at present, but its structural characteristics are not conducive to earthquake resistance. Therefore, it is of great practical significance to study the damping control of continuous girder bridges. Considering that the control device may fail due to external factors, this paper uses the magnetorheological damper as the damping device to carry out the research on the damping control of the large-span continuous girder bridge. The traditional damping control scheme is improved, and a semi-active control scheme considering fault-tolerance is proposed. That is, when some dampers fail, the fault-tolerant control algorithm provides compensation output to the control system. The seismic response and damping rate of bridges under different control schemes are compared and analyzed, and the seismic reliability of structures under different control schemes and different threshold conditions under random seismic excitation is obtained based on probability density evolution method and random ground motion model. It is found that the semi-active control scheme considering fault tolerance can still make the continuous girder bridge achieve the expected control effect when the control system has faults.

A semi-active quasi-zero stiffness vibration isolator based on magnetorheological elastomer with a fast convergence switch control

Quasi-zero stiffness (QZS) isolators have attracted extensive attention due to their high-static–low-dynamic stiffness. The effectiveness of the traditional QZS (T-QZS) isolators to attenuate low-frequency vibration has been extensively studied. The T-QZS isolator, however, cannot usually provide satisfactory vibration mitigation performance under ultra-low frequency excitation. To tackle this challenge, we propose a semi-active QZS isolator featuring magnetorheological elastomer (SAQZS-MRE isolator). The prominent merit of the proposed design is that the applied MRE material can provide varying stiffness and damping to the proposed SAQZS-MRE isolator, making the isolator suitable for vibration isolation under wide-band low-frequency range. The dynamic viscoelasticity properties of the MRE are experimentally characterized, to formulate the dynamic modeling of the SAQZS-MRE isolator. The open-loop vibration isolation characteristics of the SAQZS-MRE isolator are assessed using the harmonic balance method (HBM). Subsequently, two semi-active control strategies including skyhook and fast convergence switch (FCS) are effectively utilized in the proposed SAQZS-MRE isolator to evaluate their closed-loop performance. The results demonstrate that the SAQZS-MRE isolator with FCS control can eliminate the resonance peak and reduce the initial isolation frequency. In the higher frequency range, it can also improve the vibration isolation performance compared with the SAQZS-MRE isolator with passive control.

Mitigating borehole drill string torsional vibration and shock

This paper provides an analysis of one of the dysfunctions in borehole drill strings, which is torsional vibration. Additionally, an analysis of mitigation through systematic adjustment of the key parameters of Weight on the Bit (WOB) and Rotations per Minute (RPM) is conducted. One of the key forms of dysfunction is undesired vibration and shocks on the drill strings. The vibration and shock experienced by drill strings have a detrimental impact on equipment life, resulting from damage to the drill bit and the drill string components. This paper studies a generalized lumped-parameter model of the drill-string system to provide a fundamental understanding of the torsional stick-slip vibrations during drilling operations. The impact of various parameters such as the weight on the bit, rotational speed, and damping on the severity of vibration, in particular, stick-lip vibration, is analyzed. Various passive, active, and semi-active control strategies to mitigate the torsional vibrations have been studied and implemented with varying degrees of success, subject to continual development. From the simulation, the WOB, the drive torque, and rotational velocity determine the stick-slip onset and severity. This paper focuses on active control of the rotational speed and the weight on the bit by systematic adjustment to eliminate stick-slip while avoiding other undesirable effects and thus achieving optimum performance. Further study will be on multi-stability analysis to define the optimum operation zones and the design of vibration reduction tools and control strategies.

Semi-active structural vibrations control with magneto-rheological damper based on the hybrid fuzzy sliding mode controller

Recently, the semi-active control of structural vibration has demonstrated its ability to preserve human life and keep structures safe during earthquakes. In the civil engineering area, the literature is full of investigation in both numerical and experimental research in which the Magneto-Rheological damper is the most used device. This paper investigates the semi-active control of three scaled excited structures. The proposed control is assured by a Magneto-Rheological damper controlled using a hybrid Fuzzy Sliding Mode controller. Although, a Clipped optimal algorithm is proposed to calculate the required current for the damper operating. Otherwise, the robustness of the suggested controller is proved by the obtained numerical results of the seismic excited scaled structure. Therefore, the tested structure is subjected to four time-scaled earthquake records. Finally, the effectiveness of the proposed semi-active control strategy in mitigating earthquake structural vibration is shown clearly in the compared controlled and uncontrolled responses. The simulation results show that the peak reduction reaches 65% under the 2011 Tōhoku earthquake. In addition, the performance indices prove the robustness of the proposed strategy.