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The University of Southampton

Research project: Modelling of an electromagnetic regenerative shock absorber with a mechanical motion rectifier

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This research project is mainly concerned with the modelling of an electromagnetic regenerative shock absorber (RSA) with mechanical motion rectifier (MMR), and its performance evaluation when it is implemented in the suspension of a road vehicle.

Unlike a conventional RSA, the inclusion of a sprag-clutch within the MMR module enables the conversion of bi-directional rotational motion into unidirectional rotary input to the coupled electromagnetic generator. The MMR based system potentially works as a switchable inerter in parallel with a switchable damper. To characterise the proposed energy harvesting technique, the system is initially studied when one terminal of the design is blocked. Additionally, an analogy between the electrical and mechanical active and reactive power flow, using force-current analogy is carried out. This allows better understanding of the power transmission between sub-systems. It is shown that MMR is able to offer much superior performance than electrical rectifiers, typically for lower power application. To validate theoretical predictions, the MMR based RSA is tested in a hydraulic Instron machine. A dynamic model of the proposed design is implemented, and its parameters are estimated from the measured data.

Next, by using the concept of mechanical impedance and mobility, dynamics of the vibration source is studied when the RSA is incorporated into a road vehicle. According to the vibration source characteristic results, the implementation of the MMR based RSA in the suspension system of road vehicles enables better performance under certain conditions, but it results in a high jerk motion as a trade-off. Finally, the procedure for the design of a mechanical motion rectified RSA for a road vehicle suspension system is presented. The proposed design guidelines enable a designer to select desirable parameters for the regenerative shock absorber based on the system constraints and the application environment.

Related research groups

Mechatronics Engineering Group
Dynamics Group
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