This paper deals with an electromagnetic damper, which is composed of a permanent-magnet direct current motor, a ball screw, and a nut, as an active actuator. The main objective pursued in the paper is to study the active electromagnetic suspension system (AEMSS) considering hybrid control strategy (the hybrid control strategy is a linear combination of skyhook and groundhook control strategy). For this purpose, the nonlinear equations of the electric circuit of the AEMSS should be developed. Supposing linear conditions, the coefficients determination of the hybrid control strategy is carried out in the frequency domain using the genetic algorithm in order to improve the vehicle performance and energy regeneration simultaneously. Afterwards, the achieved coefficients are used to examine the designed AEMSS in the actual conditions for an actual road profile. The simulation results demonstrate that the designed AEMSS has the desired performance while energy can be regenerated from the road excitation and transformed into electric energy. Furthermore, it has been shown that the designed AEMSS regenerates energy during the ascent and descent of a bump and consumes energy near the top of the bump.

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This paper deals with the electromagnetic damper, which is composed of a permanent-magnet DC motor, a ball screw and a nut, as the passive, semi-active and active actuator in the vehicle suspension system. The main objective pursued in the paper is to study the dependences of the performance and energy regeneration of the electromagnetic suspension system on the road unevenness and the travel speed. For this purpose, the nonlinear equations of the electromagnetic damper electric circuit in the three mentioned suspension systems are developed. For the vehicle passing over the road unevenness, a seven degrees of freedom model is considered, and the simplest point-follower model is used for the tyre representation. To investigate the electromagnetic suspension system performance and energy regeneration, two types of road unevenness including a road section with a standard pure random profile and a bump modelled by cosine wave of variable height and length are applied. The simulation results demonstrate that an increase in the travel speed leads to the power spectral density increment of the road profile and in turn causes the negative effects on the performance and growth in the energy regeneration. Furthermore, when the bump height gets larger, maximum body acceleration, maximum suspension travel and energy regeneration will increase. There will be a peak on the maximum body acceleration response course when the bump length is equal to 1.1 m because of exciting the sprung mass frequencies. On the maximum suspension travel and energy regeneration response course, there is a peak when the travel speed is equal to 30 km/h, which excites the unsprung mass frequencies.

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This paper deals with the two degrees of freedom response-type mechanism (2 DOF RTM) designed at Iran University Science and Technology. The applications of the 2 DOF RTM are to measure the longitudinal road profile and assess the vehicle suspension system. When the 2 DOF RTM is connected to a vehicle, it is able to measure the longitudinal road profile and it is capable of assessing the vehicle suspension system while it is perched upon the exciting device. The most important part of the 2 DOF RTM is its hub planned for decreasing the vehicle movement effects on the measurement. Moreover, this paper develops a novel procedure in order to convert the measured profile from the variable speed to the constant speed. To examine the 2 DOF RTM, a profile of a road is measured by the mechanism in the time-domain, and then the highly significant roughness indices such as power spectral density (PSD) of the road unevenness, international roughness index (IRI) and present serviceability index (PSI) are estimated using the measured profile.