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This paper presents the modeling, simulation and testing of a novel eddy current damper (ECD) to be used in vehicle suspension systems. The conceived ECD utilizes permanent magnets (PMs), separated by iron poles that are screwed to an iron rod, and a conductive hollow cylinder to generate damping. Eddy currents develop in the conductor due to its relative motion with respect to the magnets. Since the eddy currents produce a repulsive force that is proportional to the velocity of the conductor, the moving magnet and conductor behave as a viscous damper. The structure of the new passive ECD is straightforward and does not require an external power supply or any other electronic devices. An accurate, analytical model of the system is obtained by applying electromagnetic theory to estimate the electromagnetic forces induced in the system. To optimize the design, simulations are conducted and the design parameters are evaluated. After a prototype ECD is fabricated, experiments are carried out to verify the accuracy of the theoretical model. The heat transfer analysis is established to ensure that the damper does not overheat, and the demagnetization effect is studied to confirm the ECD reliability. The eddy current model has 1.4 N RMS error in the damping force estimation, and a damping coefficient as high as 53 N s m−1 is achievable with the fabricated, scaled-down prototype. Finally, a full-size ECD is designed and its predicted performance is compared with that of commercial dampers, proving the applicability of the ECD in vehicle suspension systems.

The use of electromagnetic dampers (ED) in vehicle active suspension systems has drawn considerable attention in the past few years, attributed to the fact that active suspension systems have shown superior performance in improving ride comfort and road handling of terrain vehicles, compared with their passive and semi-active counterparts. Although demonstrating superb performance, active suspensions still have some shortcomings that must be overcome. They have high energy consumption, weight, and cost and are not fail-safe in case of a power breakdown. The novel hybrid ED, which is proposed in this paper, is a potential solution to the above-mentioned drawbacks of conventional active suspension systems. The proposed hybrid ED is designed to inherit the high-performance characteristics of an active ED with the reliability of a passive damper in a single package. The eddy current damping effect is utilised as a source of the passive damping. First, a prototype ED is designed and fabricated. The prototype ED is then utilised to experimentally establish the design requirements for a real-size active ED. This is accomplished by comparing its vibration isolation performance in a 1-DOF quarter-car test rig with that of a same-class semi-active damper. Then, after a real-size active ED is designed, the concept of hybrid damper is introduced to the damper design to address the drawbacks of the active ED. Finally, the finite-element method is used to accurately model and analyse the designed hybrid damper. It is demonstrated that by introducing the eddy current damping effect to the active part, a passive damping of approximately 1570 Ns/m is achieved. This amount of passive damping guarantees that the damper is fail-safe and reduces the power consumption more than 70%, compared with an active ED in an automotive active suspension system.

This paper proposes a new type of microrobot that can move along a narrow area such as blood vessels which has great potential for application in microsurgery. Also, the development of a wireless microrobot that can be manipulated inside a pipe by adjusting an external magnetic field has been discussed. The model microrobot utilizes an electromagnetic actuator as the servo actuator to realize movement in biomedical applications. The structure, motion mechanism, and evaluation characteristic of motion of the microrobot have been discussed, and the directional control can be realized via the frequency of the input current. The moving experiments have been carried out in branching points in the horizontal direction, and the moving speed of the robot has been measured in vertical direction by changing frequency. Based on the results, the microrobot has a rapid response, and it can clear out dirt which is adhering to the inner wall of pipe. This microrobot will play an important role in both industrial and medical applications such as microsurgery.

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This paper discusses the design of an eddy current passive damper using different configurations of permanent magnets. Motional eddy current damping effect is used for the development of a passive damper. Eddy currents are generated in a conductor in a time-varying magnetic field. They are induced either by movement of the conductor in a static field or by changing the strength of the magnetic field, initiating motional and transformer electromotive forces, respectively. The conceived eddy current damper consists of a conductor as an outer tube, and an array of axially magnetized, ring-shaped permanent magnets (PMs), separated by iron pole pieces as a mover. The relative movement of the magnets and the conductor causes the conductor to undergo motional eddy currents. Using this concept, damping characteristics of the new damper is obtained through analytical modeling, and verified by experimental analysis. The optimum PMs' size and configuration are also derived using analytical and finite element analysis, respectively. A damping coefficient as high as 53 kg/s is achievable with the proposed design specifications.