Browse Topic: Electromagnetic suspension

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Deep Reinforcement Learning–Based Control Strategy for Electro-Hydrostatic Active Suspension15-18-03-00167/9/2025
A DRL (deep reinforcement learning) algorithm, DDPG (deep deterministic policy gradient), is proposed to address the problems of slow response speed and nonlinear feature of electro-hydrostatic actuator (EHA), a new type of actuation method for active suspension. The model-free RL (reinforcement learning) and the flexibility of optimizing general reward functions are combined with the ability of neural networks to deal with complex temporal problems through the introduction of a new framework called “actor-critic”. A EHA active suspension model is developed and incorporated into a 7-degrees-of-freedom dynamics model of the vehicle, with a reward function consisting of the vehicle dynamics parameters and the EHA pump–valve control signals. The simulation results show that the strategy proposed in this article can be highly adapted to the nonlinear hydraulic system. Compared with iLQR (iterative linear quadratic regulator), DDPG controller exhibits better control performance, achieves the EHA control objective at faster speed, and notably improves the ride comfort and handling stability of the car. Moreover, DDPG’s optimized valve–pump joint control strategy can reduce the energy consumption of the EHA system and improve the life of the hydraulic components while ensuring the control accuracy, solving the problem of low reliability of the active suspension system.
Wang, Jiawei, Guo, Huiru, Deng, Xiaohe
Research on Multi-Mode Switching Strategy for Electromagnetic Suspension2024-01-700511/15/2024
This study proposes a multi-mode switching control strategy based on electromagnetic damper suspension (EMDS) to address the different performance requirements of suspension systems on variable road surfaces. The working modes of EMDS are divided into semi-active damping mode and energy harvest mode, and the proposed mode switching threshold is the weighted root mean square value of acceleration. For the semi-active damping mode, a controller based on LQR(Linear Quadratic Regulator) was designed, and a variable resistance circuit was also designed to meet the requirements of the semi-active mode, which optimized the damping effect relative to passive suspension. For the energy harvest mode, an energy harvest circuit was designed to recover vibration energy. In order to reduce the deterioration of suspension performance caused by frequent mode switching in the mode switching strategy, as frequent system switching can lead to system disorder, deterioration of damping effect, and reduction of energy harvest efficiency, two switching conditions are introduced to increase system stability, namely mode switching judgment frequency and sampling interval time. The setting of mode switching judgment frequency is to avoid sudden and occasional switching, while the setting of sampling interval time is to obtain a more reasonable weighted acceleration root mean square value. By selecting these two parameters reasonably, the stability and effect of mode switching can be optimized. The results indicate that the multi-mode switching control strategy can achieve reasonable switching of electromagnetic suspension in two modes, achieving good vibration reduction effect and certain energy harvest capability.
Zeng, Sheng, Zhang, Bangji, Tan, Bohuan, Qin, An, Lai, Jiewen, Wang, Shichen
Hierarchical Control Strategy for Active Suspension Equipped with an Electromagnetic Actuator2023-01-707712/31/2023
Electromagnetic suspension systems have increasingly gained widespread attention due to their superiority in improving ride comfort while providing fast response, excellent controllability and high mechanical efficiency, but their applications are limited due to the accuracy of the underlying control actuation tracking. For addressing this problem, this study presents a novel hierarchical control strategy for an electromagnetic active suspension (EMAS) system equipped with an electromagnetic actuator (EMA) structure. The structure of the EMA device and the working principle of the motion conversion model are introduced in detail first, and the motion conversion equation is derived based on the force-torque relationship. Based on this, a linear quadratic regulator (LQR) control method is proposed to be applied to a half-vehicle suspension system to improve the vibration isolation performance of the vehicle and ensure the ride comfort. Then, the underlying layer control of the permanent magnet synchronous motor (PMSM) based on field-oriented control (FOC) is adopted to tracking the active control forces generated by the upper LQR controller. Immediately afterwards, the EMA converts the torque generated by the motor into vertical forces acting on the suspension through rational synergies between the upper LQR controller and the underlying motor controller, which ultimately achieves active control of the vehicle suspension system. The simulations are carried out from the perspective of the half-vehicle integrated with the EMA, which demonstrate that the proposed EMAS system has greatly reduced vehicle vertical and pitch accelerations compared to the conventional passive suspension, significantly improving the ride comfort and vibration isolation effect on external excitation.
Lai, Jiewen, Zhang, Bangji, Qin, An, Zeng, Sheng, Wang, Shichen
Research on Vibration Control and Energy Study of Vehicle Electromagnetic Suspension Based on Sliding Mode Control2023-01-708412/31/2023
This article proposes an electromagnetic damper (EMD) based on a ball screw mechanical structure actuator. To prove the damping effect of the new damper proposed in this paper. In this paper, the EMD suspension is validated on a quarter vehicle suspension. A mathematical model of quarter vehicle suspension is developed and a sliding mode variable structure controller is designed. This sliding mode controller enables vibration control of the suspension and improves ride comfort. To make the EMD track the ideal current effectively, a variable resistance circuit that can change the electromagnetic damping force is proposed to achieve the graded adjustment of resistance. A semi-active vehicle vibration control strategy was designed, and experiments were conducted using a quarter-vehicle test platform to verify the vibration-damping performance of this EMD suspension. The energy transfer to the road was analyzed and the higher the variable resistance, the more energy is transferred to the vehicle. The experimental results show that the EMD suspension reduces the acceleration RMS by 25.53 %, 23.57 % and 16.48 % under sinusoidal, bump and random road conditions, respectively, compared to the passive suspension. This ensures that the dynamic travel of the suspension and the dynamic loading of the tire is within reasonable limits. The energy of the road surface, the energy consumed by the EMD, the energy transferred to the tire and the energy of the vehicle were also analysed. The experimental results show that the lower the resistance in the EMD circuit, the less energy is transferred to the vehicle, and that the EMD suspension reduces the energy transferred from the road surface to the vehicle by 8 % compared to the passive suspension under random road conditions. The experiment proves that it greatly improves the comfort of the vehicle while ensuring the stability of vehicle control.
Zhou, Xiangru, Liu, Pengfei, Ning, Donghong, Yu, Jianqiang, Du, Haiping
Electrically Interconnected Suspension and Related Technologies: A Comprehensive Review10-07-03-00248/10/2023
The electrically interconnected suspension (EIS) is a novel suspension system that has gained attention due to its potential to improve vehicle vibration control. This article provides a comprehensive review of EIS and related technologies. It starts with an overview of the research on hydraulic interconnected suspension (HIS) and its limitations. Then, it discusses the development of the electromagnetic suspension (EMS) and its advantages in adjusting mechanical characteristics. The article focuses on the electrical network and decoupling control characteristics of EIS, demonstrating the principle of synchronous decoupling control of multiple vibration modes. A comparison of the structure and control characteristics of EIS and HIS highlights the advantages of EIS in vehicle vibration control. The article concludes by identifying some unresolved issues and potential research areas to guide future studies on EIS, such as improving the controllability and energy efficiency of EIS systems.
Du, Haiping, Liu*, Pengfei, Ning*, Donghong, Zhang, Nong
Nonlinear Force Model of Electromagnetic Damper and Its Influence on Vibration Control2021-01-03194/6/2021
In this paper, a nonlinear force model of an electromagnetic damper (EMD) is established and the model’s parameters are obtained by experiments. The effect of nonlinear force on vibration control of vehicle suspension system is analyzed by comparing the simulation data. Firstly, according to the mechanical and circuit structure of the EMD, a nonlinear model including electromagnetic force, friction force, and inertial force is established. Based on the EMD bench test, the mechanical parameters of the DC motor and the ball screw are obtained by the least square method. Then a quarter-car model including the electromagnetic suspension is established. By analyzing the transmission rate of the suspension response to the road excitation, the nonlinear force of the EMD shows an obvious influence on the high-frequency vibration performance of the suspension. Finally, using the linear quadratic regulator (LQR) controller combined with the control logic of the semi-active EMD, the vibration control performance of the vehicle suspension under bump and random excitation is analyzed through numerical simulation. The results show that the nonlinear force of the EMD deteriorates the sprung mass acceleration (SMA) and the dynamic tire deformation (DTD), but improves the deflection of suspension (DDS). Moreover, in the nonlinear force of EMD, the influence of inertia force on suspension vibration control performance is more obvious than friction force.
Liu, Pengfei, Zheng, Minyi, Luo, Liang, ning, Donghong, Zhang, Nong
Actively suspending off-road vehiclesOFHFEB01_042/1/2001
The University of Texas Center for Electromechanics evaluated a retrofit electromechanical active suspension that shows promise of improved cross-country mobility for military vehicles. Passive suspension systems compromise ride quality with handling. An active suspension system, on the other hand, can discriminate between vertical suspension displacements associated with terrain variations and those associated with the vehicle rollover forces during turning. As such, active elements in the suspension can respond to provide both a soft: and comfortable ride with limited body roll during turning. Hydraulic active suspension systems have achieved only limited success in off-road applications because response lag from hydraulic actuators results in a transmission of terrain harshness to the body structure. A study by the University of Texas Center for Electromechanics (UT-ECM) demonstrated the performance of an electromagnetic (EM) active force-producing element that is reversible.
Superconducting Maglev and its Electromagnetic Characteristics9519228/1/1995
A new test line of superconducting maglev is under construction, reflecting the results of Miyazaki test line. The null flux levitation system arranging 8-figured levitation coils on the sidewall is installed about 2km long in the middle part of the 7km guideway. The characteristics of the levitation, guidance and propulsion system have been tested with the test vehicle MLU002N. The results agreed well with analytical ones. As levitation and guidance forces were larger than those of normal flux system, lower take-off speed was attained on this section. The new test line of 42.8km long adopts this null flux system, implementing those results. Vehicle and coils to be tested on the new test line are summarized as far as they are related to electromagnetic characteristics are concerned.
Fujiwara, Shunsuke
The Transrapid Maglev System - An Update9215838/1/1992
This paper presents the status of the Transrapid Maglev System and the first commercial super-speed maglev application in the world planned for Orlando, Florida. It includes a brief summary of SAE paper No. 89 1714 which was presented in August 1989 and covers subsequent developments. It also includes some discussion of institutional factors to be considered when planning the implementation of a new system. The purpose of this paper is to provide an update on the status of the 500 km/hr super-speed magnetically levitated ground transportation system that was developed in Germany. This maglev system features contactless electromagnetic suspension and long stator three-phase propulsion. This transportation mode has little effect on the environment, is safe and cost effective.
Dickhart, William W.
The Transrapid Maglev System8917148/1/1989
A 300 mph (500km/hr) magnetically levitated ground transportation system, developed in Germany, is now ready for revenue application. The Maglev system features contactless electromagnetic suspension and long stator three-phase propulsion. This transportation mode has little effect on the environment, is safe, and is cost effective. A revenue system is planned in Germany and a proposal for a system in Florida is under consideration.
Dickhart, William W.
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