Active Metamaterial Cell Using Non-Collocated Velocity Feedback (vor Ort)
* Presenting author
This paper deals with the development of an active metamaterial cell which does not obey the principle of dynamic reciprocity. Within the metamaterial cell two decentralized velocity feedback loops are implemented, where the sensor-actuator transducers are non-collocated. A lumped parameter mathematical model of the active electromechanical system is derived. The model is used to conduct a detailed analysis of the system in terms of stability, paying special attention to the selection of parameters of the passive system which would ensure good stability margins. It is shown that, when the dynamics of the sensors and actuators are neglected, the system can be made unconditionally stable despite the non-collocated transducer arrangement. However, when these dynamics are taken into account, no such property can be guaranteed and the system becomes conditionally stable. Nevertheless, a substantial gain margin can be expected. The theoretical model is verified using a 3D printed experimental prototype of the metamaterial cell. Measurements were made both with and without active control. A considerable loss of dynamic reciprocity is registered when the active control is present, along with a substantial vibration transmission reduction in one direction, accompanied by a vibration transmission increase in the opposite direction.