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Electromagnetic damper (EMD), which has shown good vibration isolation and energy harvesting potential, has received much attention in recent years. In addition, the harvested energy of EMD systems can be used to further suppress severe vibration. When the harvested energy of the suspension system is more than the consumed energy, the suspension system can realize self-powered functions. However, the integration of the above three functions is a challenge for the design of EMD systems. In this paper, a novel multi-function electromagnetic damper (MFEMD) system, which integrates the semi-active vibration control mode, energy-harvesting mode, and self-powered mode, is introduced first. The MFEIS system applies an H-bridge circuit to control the multi-directional flow of circuit energy flow, and the supercapacitor is used as the energy storage device because of its high-power density and rapid response speed. Since vehicles are driving in complex road conditions in the real world, road information needs to be considered to control the MFEMD system. Additionally, the energy recovery efficiency and vibration suppression performance of the MFEMD system also need to be balanced. A switchable control strategy based on road classification is proposed to switch the state of the MFEMD system. According to the real driving conditions, roads are classified into three categories, namely high-speed smooth roads, medium-speed good roads, and low-speed bad roads. The state of the MFEMD system is switched based on the road information to balance the ride comfort and energy recovery efficiency. A complex road, which contains different levels of random roads, is adopted to verify the effectiveness of the proposed control strategy. Simulation results verified the effectiveness of the proposed switchable control strategy compared with a well-tuned passive suspension and a semi-active suspension.

Overshoot and long settling time are two common problems of the positioning control for robotic arms. To solve the positioning control problems, an innovative variable stiffness and variable damping (VSVD) magnetorheological (MR) actuation system for robotic arms was designed, prototyped and evaluated in this paper. The system can reduce the overshoot and settling time of the robotic arm with less energy consumption by controlling the stiffness and damping of its VSVD unit. A robotic arm with the VSVD actuation system was developed and prototyped. In order to evaluate the performance of the system, a step route and a customised route were designed for the robotic arm system to trace. Under these two routes, the positioning control performances of the VSVD robotic arm were evaluated numerically and experimentally with the control modes of uncontrolled, VD, VS and VSVD, respectively. Both the numerical and experimental results demonstrated that the VSVD control mode works best in general with less overshoot, settling time and energy consumption, indicating that the proposed VSVD actuation system can serve as a good candidate to solve the positioning control problems of robotic arms.

This paper proposes a novel semi-active electromagnetic device with the capability of variable inertance and damping (VIVD) and an energy storage priority control (ESPC) strategy for vibration reduction of vehicle seat suspensions. The VIVD device can control its inertance and damping by adjusting resistances in a variable admittance (VA) circuit different from the traditional mechanical damper. The circuit and mechanical dynamics model of the VIVD seat suspension is analyzed and verified with tests, and the energy storage characteristic and controllability of the VIVD device are explored. Also, the frequency response characteristics of the VIVD device are derived from the admittance characteristics of the VA circuit. For the semi-active VIVD seat suspension, an H controller is designed to obtain the desired control force. An ESPC strategy is proposed to make the electromagnetic force of the VIVD device track the desired control force. The test results show that the VIVD seat suspension can successfully suppress the seat's vibration, which is better than the traditional variable damping seat suspension performance. Under the random excitation, the root means square acceleration of the VIVD seat is reduced by 32.99% compared with a passive seat. This new semi-active VIVD device shows great potential in engineering applications.

In order to ensure the detection accuracy, an improved adaptive weighted (IAW) method is proposed in this paper to fuse the data of images and lidar sensors for the vehicle object’s detection. Firstly, the IAW method is proposed in this paper and the first simulation is conducted. The unification of two sensors’ time and space should be completed at first. The traditional adaptive weighted average method (AWA) will amplify the noise in the fusion process, so the data filtered with Kalman Filter (KF) algorithm instead of with the AWA method. The proposed IAW method is compared with the AWA method and the Distributed Weighted fusion KF algorithm in the data fusion simulation to verify the superiority of the proposed algorithm. Secondly, the second simulation is conducted to verify the robustness and accuracy of the IAW algorithm. In the two experimental scenarios of sparse and dense vehicles, the vehicle detection based on image and lidar is completed, respectively. The detection data is correlated and merged through the IAW method, and the results show that the IAW method can correctly associate and fuse the data of the two sensors. Finally, the real vehicle test of object vehicle detection in different environments is carried out. The IAW method, the KF algorithm, and the Distributed Weighted fusion KF algorithm are used to complete the target vehicle detection in the real vehicle, respectively. The advantages of the two sensors can give full play, and the misdetection of the target objects can be reduced with proposed method. It has great potential in the application of object acquisition.

The stability analysis is studied for H

This paper presents a smart passive MR damper with fast-responsive characteristics for impact mitigation. The hybrid powering system of the MR damper, composed of batteries and self-powering component, enables the damping of the MR damper to be negatively proportional to the impact velocity, which is called rate-dependent softening effect. This effect can keep the damping force as the maximum allowable constant force under different impact speed and thus improve the efficiency of the shock energy mitigation. The structure, prototype and working principle of the new MR damper are presented firstly. Then a vibration platform was used to characterize the dynamic property and the self-powering capability of the new MR damper. The impact mitigation performance of the new MR damper was evaluated using a drop hammer and compared with a passive damper. The comparison results demonstrate that the damping force generated by the new MR damper can be constant over a large range of impact velocity while the passive damper cannot. The special characteristics of the new MR damper can improve its energy dissipation efficiency over a wide range of impact speed and keep occupants and mechanical structures safe.

This paper presents the modelling and experimental evaluation of a semi-active vehicle suspension installed with a self-powered MR damper which is able to perform variable stiffness. Its variable stiffness feature as well as the self-powering capability was evaluated and verified using a hydraulic Instron test system. The testing results show that the stiffness of the damper is dependent on the current which can be generated by the self-powering component. A mathematic model was established to describe the dynamic properties of the MR damper and its power-generating capability. Finally, the self-powered MR suspension was installed on a quarter car test rig for its vibration isolation evaluation. A controller based on the short-time Fourier transform (STFT) was developed for the stiffness control. The evaluation result illustrates that the proposed MR damper can reduce the acceleration and displacement of the sprung mass by 16.8% and 21.4% respectively, compared with the passive system.

© 1982-2012 IEEE. This article introduces a rotary semiactive variable stiffness (VS) device, including its system design and model validation. A variable damping (VD) device and springs can form mechanical networks with specific topologies, and the VD device can control the equivalent stiffness of the network by varying its damping. The proposed rotary electromagnetic VS device consists of an electromagnetic VD device and a torsion spring, which are in series, while a planetary gear reducer is used to amplify the torque output of the VS device. The models of the electromagnetic VD and VS devices are both built and validated with tests. Then, a seat suspension applies the VS device by installing the device in the center of its scissors structure. Bump and random vibration experiments are implemented to validate the effectiveness of the proposed VS system for seat suspension vibration control. The new system has merits in controllability and energy efficiency. It is easier to design the controller than the conventional one with magnetorheological damper due to the linear damping of the electromagnetic VD device. Besides, the system energy consumption is low and has energy harvesting capability. The proposed semiactive electromagnetic VS device also has potential in other practical applicationss.

Numerous research studies have been performed to help develop advanced control algorithms for semi-active seat suspension. This paper experimentally investigates a state observer-based Takagi-Sugeno (T-S) fuzzy controller for a semi-active seat suspension by equipping an electrorheological (ER) damper. A new ER damper prototype is designed, assembled, and tested. Then, a T-S fuzzy model is established to describe the ER seat suspension, which can facilitate the $\text{H}\infty $ controller design considering the multi-objective optimization. A state observer is established and integrated into the controller to estimate the state information for the T-S fuzzy model in real-time. Additionally, the experimental validation of the control algorithm is critical in the practical application. A seat suspension test rig is built to validate the effectiveness of the proposed controller. The presented control algorithm is evaluated by comparing the corresponding test results to those with a skyhook controller. The experimental results demonstrate that the proposed T-S fuzzy control method, compared to the traditional control method, can further improve the performance of an ER seat suspension system.

As the concept of variable stiffness and variable damping (VSVD) has increasingly drawn attention, suspensions applied with magnetorheological (MR) dampers to achieve varying stiffness and damping have been an attractive method to improve vehicle performance and driver comfort further. As highly nonlinearity of MR damper dynamics and coupled interconnections in the case of multi-output control, to build a direct control system for VSVD suspension based on multiple MR dampers is difficult. Applying Takagi-Sugeno (T-S) fuzzy model on the VSVD system enables the linear control theory to be directly utilized to build the multi-output controller for multi-MR dampers. In this paper, a T-S fuzzy model is established to describe an MR VSVD suspension model, and then an H∞ controller that considers the multi-input/multi-output (MIMO) coupled interconnections characteristic and multi-object optimization is designed. To estimate state information for the T-S fuzzy model in real-time, a state observer is designed and integrated in the controller. Then, the performance of the VSVD control algorithm was evaluated by numerical simulation. The results demonstrate that the T-S fuzzy model-based H∞ controller outperforms the independent control method for a VSVD suspension system with multi-MR dampers.

This paper presents the concept of the variable admittance network (VAN) with indirect energy supply for semiactively controlled systems and the admittance analysis of three basic VANs with indirect energy supply in resonance vibration control. A mechanical network is describable with the admittance, which includes the damping, stiffness, and inertance information. The VAN with variable admittance parameters is beneficial for the resonance vibration control of the suspension. However, according to the energy analysis, the variation of inertance and stiffness parameters without direct energy supply to compensate kinetic energy will cause the mechanical itemsʼ physical discontinuity as the inerter and spring can store kinetic energy. The variable damping (VD) device applies the indirect energy supply that is only related to the damping control but not to the exchange with kinetic energy. This paper proposes the VAN with indirect energy supply to achieve the VD, variable equivalent inertance (VEI), and variable equivalent stiffness (VES) characteristics by controlling a VAN with only the VD device in it. The vibration transmissibility of a suspension equipped with VD, VEI, and VES devices is investigated, respectively, to verify their effectiveness in resonance vibration control. The VAN with indirect energy supply is realizable in different applications; the admittance analysis method can facilitate the VAN design and optimization in practice.

This paper establishes a 7-degree-of-freedom full-vehicle suspension system with two 2-degree-of-freedom controllable electrically interconnected suspensions (EIS) to achieve the control effect of the entire vehicle. The motions between the sprung mass and unsprung masses are converted into electrical energy via the electromagnetic suspensions, and then the energy is electrically interconnected with the electrical network (EN). This research is based on the previous study of a 2-degree-of-freedom EIS system, which shows the vehicle performance at heave and roll is improved by controlling resistances in the EN. On this basis, this project utilizes the genetic algorithm (GA) and regards the parameters of variable resistors in EN as the optimizing targets. Based on the factors of vehicle comfort and suspension deflection limits, the 11 control objectives have been defined in order to achieve optimal performance through GA optimization. The final parameters of the resistors $\boldsymbol{R_{e}}$ and $\boldsymbol{R_{l}}$ in the EN are obtained as $\boldsymbol{14.78\Omega}$ and $\boldsymbol{7.29\Omega}$ , respectively. Both the time-domain simulation and the frequency weighted root mean square analyses show that the three sprung mass accelerations of the full vehicle have been significantly improved. The optimized vertical heave acceleration has decreased by 48.13%, while the roll and pitch angular acceleration has also decreased by 34.91% and 49.76%, respectively. These outcomes have sufficiently proved the effectiveness of GA optimization for the vehicle model. Furthermore, the EIS system can also benefit from the reduction of motion sickness; the optimized motion sickness dosing value has reduced almost 45.43% compared with the initial value

Tuned mass damper technologies are progressively advancing through innovative application of smart materials, facilitating more versatile infrastructure protection. During seismic events, primarily encountered surrounding fault lines, high-rise buildings and other civil structures can suffer catastrophic failures if not adequately protected. Where traditional passive structural protection may mitigate such damage, adaptive systems which provide controllable vibration attenuation across a wide range of excitation frequencies have seen growth in use, overcoming the challenges resulting from unpredictable seismic spectrums. As a robust solution to this problem, this article presents and analyses a variable resonance magnetorheological-fluid-based pendulum tuned mass damper which employs a rotary magnetorheological damper in a controllable differential transmission to add stiffness to a swinging pendulum mass. The device is mathematically modelled based on magnetic field analysis, the Bingham plastic shear-stress model for magnetorheological fluids, and planetary gearbox kinematic and torque relationships, with the model then being validated against experimental data. The passive and semi-active-controlled performance of the device in seismic vibration suppression is then experimentally investigated using a scale five-storey building. In tests conducted with the 1985 Mexico City record, the semi-active device outperformed the (optimal) passive-on tuning, at best reducing peak displacement by 15.47% and acceleration by 28.28%, with similar improvement seen against the passive-off case for the 1940 El Centro record.

In this paper, a novel semi-active variable admittance (VA) concept is proposed, and a seat suspension prototype with a magnetorheological fluid damper based rotary VA device is designed, manufactured, and experimentally validated. The conventional inerter with a single flywheel has a constant inertance, which can effectively improve the suspension performance by being integrated into a mechanical network with springs and dampers. The proposed rotary VA device comprises a gear reducer, two flywheels and a variable damping (VD) device which is used to connect the two flywheels. With carefully designing, the rotary VA device is compacted and is similar with a VD device in size. The rotary VA device is installed in the centre of a seat suspension's scissors structure to form a VA seat suspension. According to the test results, the equivalent inertance of the seat suspension can vary from 11.3 Kg–76.6 Kg with a 3 Hz frequency and 5 mm amplitude sinusoidal movement by changing the current from 0 A–1 A. By analysing the system characteristics, a hybrid controller with two acceleration feedbacks is proposed. Thereafter, the seat suspension and controller are validated in experiments by comparing the performance with a conventional passive seat suspension. The random vibration test shows the excellent performance of the proposed seat suspension; the frequency weighted root mean square acceleration of the seat is reduced by 43.6%, which indicates a great improvement of the ride comfort. The VA device shows great prospect in the suspension application.

The noise and vibration effects of rails can have a significant impact on the environment surrounding the railways. Rail dampers are elements that are attached to the sides of the rail and can improve the track decay rate of rail and then enhance the rails’ ability to attenuate noises and vibrations. However, in practical applications, the most efficient rail damper design still cannot adjust its own parameters to adapt to different requirements because their stiffness and damping are fixed after designed. In this work, a tunable magnetorheological elastomer rail damper that works on the principle of a dynamic vibration absorber has been designed, analysed, characterised, and experimentally tested for the suppression of railway noise and vibration. The new rail damper incorporates variable stiffness magnetorheological elastomer layers, whose stiffness can be controlled by an externally applied magnetic field, to realise adaptive characteristics. Experimental characterisations of the magnetorheological elastomer rail damper were performed with an electromagnetic shaker. Subsequently, theoretical predictions of the track decay rate of a UIC-60 rail with different rail dampers and without rail damper were conducted; simulation results verified that magnetorheological elastomer rail dampers can improve the track decay rate of rail over a wider frequency range compared to conventional rail dampers and thus the performance of the magnetorheological elastomer rail damper outperforms other conventional rail dampers on rail noise reduction.

As the concept of variable stiffness (VS) and variable damping (VD) has increasingly drawn attention because of its superiority on reducing unwanted vibrations, dampers with property of varying stiffness and damping have been an attractive method to further improve vehicle performance and driver comfort. This paper presents the design, prototyping, modeling, and experimental evaluation of a VS and VD magnetorheological (MR) vehicle suspension system. It was first characterized by an INSTRON machine. Then, a phenomenological model was proposed to capture the characteristics of the damper and TS fuzzy approach was used to model the quarter car system where the proposed damper was installed. Different controllers, including skyhook, short-time Fourier transform and state observer based controller were designed to control the damper. Experimental results demonstrate that the quarter car system with the VS and VD suspension performs best in terms of reducing the sprung mass accelerations comparing with other suspensions.

Of the recent developments in legged robotics, compliance control of legs has potential to make a huge impact in the transition from simple mechanisms to life-like machines. Given the nature of legged locomotion in humans and animals involves such compliance control, this is a step forward in terms of the artificial embodiment of the biological traits that make these living beings superior to the robots we have today. Taking a literal Rolling Spring Loaded Inverted Pendulum (R-SLIP) morphology, this work proposes a magnetorheological-fluid-centric (MRF) variable stiffness leg, aiming to further investigate this area and take advantage of the improved energy efficiency and gait stability made possible through leg stiffness control. With the potential for adaptive tunability of leg stiffness through semi-active control, the design is shown to be capable of a maximum stiffness increase of 257%, with behaviour predicted by a force model describing the mechanism. In subsequent dynamic locomotion testing was conducted and the testing results demonstrate that the new leg is able to reduce cost-of-transport (CoT) and verified the potential of the MRF leg on improving the locomotive performance.

This article presents a novel rotary shock absorber which combines the abilities of variable stiffness and variable damping by assembling a set of two magnetorheological damping units, one of which being placed in series with a rubber spring. This allows the damping and stiffness to be controlled independently by the internal damping and the external damping units, respectively. A test bench was established to verify the variable stiffness and damping functionality. The experimental results for variable damping test, variable stiffness test and co-working test are presented. At the amplitude of 10° and the frequency 0.5 Hz, increases of 141.6% and 618.1% are obtained for damping and stiffness separately if the corresponding current increased from 0 to 1 A and from 0 to 2 A, respectively. A mathematical model is then developed and verified to predict the changing of the damping and stiffness. The test results and the simulated model confirm the feasibility of the shock absorber with the ability of varying damping and stiffness simultaneously.

Seismic events leading to catastrophic outcomes around the world, particularly in built-up regions surrounding fault lines, often have high death tolls and cause costly damages to societies’ existing infrastructure. To suppress damaging vibrations in multi-story buildings across a wide frequency spectrum, much research has been put into the study of variable-resonance tuned mass dampers, which maintain their usefulness across a range of frequencies, unlike passive alternatives. As a novel implementation of fast responsive magnetorheological materials to enable variable resonance, this paper presents a prototype magnetorheological-fluid-based pendulum tuned mass damper, integrating a differential gearbox to yield a damper-controlled transmission between the pendulum mass and a mechanical spring. The device is demonstrated to be highly effective, at its best reducing peak relative displacement by 12.8%, and peak acceleration by 22.0%, in contrast to comparable passive tuning modes in scale-building seismic experiments. This is owed to its controllable resonance which can be increased by 104% from its base value at 2.24 Hz. Further, other performance benefits are demonstrated in RMS structure displacement, and interstory drift ratio.

In this paper, the problem of the output reachable set estimation is investigated for seat suspension systems. A singular seat suspension system is established, and the definition of the output reachable set is given. The acceleration and deflection are defined as the output of the singular seat suspension system, and their reachable set is estimated. The simulation results are shown to illustrate the effectiveness of the proposed method.

In this chapter, a novel electromagnetic variable inertance (EMVI) device is designed for vehicle vibration reduction, which consists of a controllable damper and an inerter in serial. First, the composition of the EMVI system is introduced and its mathematical model is established. Next, based on the time and frequency domain simulation, the control methods and dynamic control effects of the EMVI device are studied. Simulation results show that the EMVI device can achieve variable inertance by PWM signal control. To verify the performance of the EMVI device for vehicle suspension, a quadratic optimal controller was designed for real-time control of the EMVI suspension. The overall performance of EMVI suspension and conventional suspension under sinusoidal and random road excitation is compared. The results confirmed that the EMVI device can improve the suspension performance of a vehicle. Furthermore, it can effectively reduce the vibration of the vehicle body in the frequency range of 1 to 3 Hz.

This paper proposes a novel decoupling vibration control method for the semi-active electrically interconnected suspension (EIS) and develops a mechanical hardware-in-the-loop (mHIL) test platform to verify the effectiveness of the method. Firstly, according to the decoupling characteristic of the interconnected electrical network, the half-car model is divided into vertical and roll ones, and their frequency response could show the capability of EIS on vibration control. Then, two H ∞ state feedback controllers are designed based on the decoupled model to acquire the ideal force and torque for vertical and roll vibration control; the adjustment logics of the resistance control unit are proposed to track the ideal force and torque. Finally, the mHIL experiment platform is designed to validate the decoupling vibration control performance of the EIS system. In the experiment, the EIS can significantly improve the vehicle suspension's overall performance under sinusoidal and bump road excitations compared with that of the passive suspension. On the C-level random road, the test results show that the EIS can reduce the root-mean-square vertical and roll angular accelerations of the sprung mass by 22.90% and 21.75%, respectively, which significant improvement the ride comfort of the vehicle.

This paper proposes a singular system-based approach for active vibration control of vehicle seat suspensions, where the drivers' acceleration is augmented into the conventional seat suspension model together with seat suspension deflection and relative velocity as system states to make the suspension model as a singular system. In this novel seat suspension system, all the system states are easy to measure in real-time. A friction observer is applied to estimate the real system friction and an H∞ controller is designed to achieve the optimal ride comfort performance with consideration of the friction compensation, actuator saturation, and time delay issues. The cone complementarity linearization (CCL) algorithm is applied to solve the nonlinear constraints. The experimental results show that good ride comfort performance can be achieved by the proposed controller in both the time and frequency domain compared with the uncontrolled seat suspension.

© 1996-2012 IEEE. In this article, we propose a novel controllable electrically interconnected suspension (EIS) for improving vehicle ride comfort, which is systematically studied and experimentally validated. Different to the mechanical or hydraulic energy in the traditional interconnected suspensions, the EIS system is interconnected with the electrical energy that is transformed from vibration energy by independent electromagnetic suspensions. We introduce a two-degree-of-freedom (two-DOF) EIS system comprising a controllable electrical network (EN) and two independent electromagnetic suspensions to present the system design and analysis method. The electromagnetic suspension's mechanical characteristics are related to the applied electrical elements. Similarly, the EN of the EIS can determine the heave and roll dynamics. Experiments are implemented to validate the system model. The EIS system is then applied in a half-car model with one kind of EN topology. The frequency and time domains simulations show that the vehicle performance at heave and roll are both improved by controlling resistors in the EN. The proposed EIS system can determine the suspension characteristics (damping, stiffness, and inertance) in different DOFs with electrical elements, and the EN is easy to embed into the vehicle system. Besides, the system only requires energy for controlling the electrical elements, which is very low. The EIS system shows great potential in the practical applications.