This article proposes a novel semiactive 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 semiactive 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 semiactive VIVD device shows great potential in engineering applications.

This article 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 hydraulically interconnected suspensions have been utilized to improve ride comfort and prevent rollover, whereas 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 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 semiactive control strategy based on ${\mathbf{H}}_\infty $ 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% compared to nonversatile EIS. The proposed versatile EIS system has great potential in practical application.

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.

Electrically interconnected suspension (EIS) is an emerging technology for vehicle vibration control. This article proposes an acceleration-measurement-based disturbance compensation control strategy for vehicles with EIS. The EIS system has the decoupling characteristic, and it can achieve variable inertance and variable damping capability in the heave direction and variable stiffness capability in the roll direction. The EIS is interconnected with electrical components, providing more flexibility than mechanically and hydraulicly interconnected systems with similar versatile functions. In applying the EIS, accurately describing unmeasurable disturbances caused by friction forces, simplifying the model, and dealing with the nonlinearity of the electrical network pose challenges. Thus, this article introduces a disturbance observer that utilizes acceleration measurements in the heave and roll directions to estimate unknown disturbances in their respective directions. For each direction, the gains of the disturbance observer and ${\mathbf{H}}_\infty $ controller are obtained simultaneously using the linear matrix inequality method, which simplifies the implementation process. The control strategy utilizes the measured vertical acceleration and angular acceleration of the sprung mass to form a closed-loop feedback control, enhancing robustness. Finally, the effectiveness of the proposed disturbance compensation controller is demonstrated through experiments conducted on a half-car test rig. The results show significant improvements in vibration control compared to both passive suspension systems and EIS systems without disturbance compensation. The proposed observer is cost-effective and easy to implement in practice.

Semi-active devices have been extensively studied for seat suspension to improve passenger riding experience. However, the traditional semi-active devices can only control the amplitude of the generated force and cannot change the direction of the force as needed. This paper proposes a vibration control method for a new seat suspension with a magnetorheological (MR) damper-based controllable inerter (MRDCI) to break the performance bottleneck of the traditional semi-active seat suspension. The MRDCI consists of two MR dampers, two sets of rack and pinion, and a flywheel. The device can convert reciprocating vibration into unidirectional shaft rotation, and the flywheel can release stored energy to generate a controllable force for vibration reduction. It can work as a controllable inerter. Then, a semi-active controller for the seat suspension is designed for vibration control, and it includes a sliding mode controller that calculates the desired control force and a semi-active control strategy for the control of MRDCI to track the desired control force. Finally, experimental tests are conducted to verify the vibration control performance of the suspension. The results show that the new suspension performs better than the traditional passive and semi-active variable damping (VD) suspensions. Under road excitation, the proposed seat suspension’s RMS acceleration and FW-RMS acceleration are reduced by 9.38% and 15.8% compared to the traditional semi-active VD seat suspension.

Seat suspension plays a vital role in improving riding comfort and protecting drivers’ health. This paper develops semi-active seat suspension that equips a controllable electromagnetic damper (EMD) and proposes a prescribed performance control-based semi-active vibration controller with experimental validation. The semi-active EMD mainly consists of a permanent magnet synchronous motor, a ball screw, a three-phase rectifier, and a controllable external resistor, which can vary its damping from $90$ to $800 \mathrm{N}·\mathrm{s}/\mathrm{m}$ by tuning the controllable external resistor in real-time. The EMD is applied to seat suspension, and a semi-active controller is proposed for the EMD seat suspension. In order to control the seat suspension vibration, a prescribed performance method is applied to obtain a desired control force and then a force-tracking strategy is designed to make the EMD track the desired control force. Finally, the semi-active seat suspension with the proposed controller is tested in experiments with different vibration conditions. The semi-active seat suspension performs excellently for the bump, sine wave and random vibration. The root mean square (RMS) acceleration, the frequency-weighted RMS acceleration and the acceleration’s fourth power vibration dose value were reduced by $17.5\%$, $39.9\%$, and $25.4\%$, respectively, in the random vibration, compared with a passive system.