On external model controller of vibrations

University dissertation from Luleå : Luleå tekniska universitet

Abstract: A promising way to increase the suppression of vibration in mechanical systems is to apply active damping instead of passive damping, which is most widespread today. An active damper system consists of an actuator, a controller and at least one sensor, usually an accelerometer. The sensor measures the vibration and sends the measurements further to the controller in order to calculate the necessary damping force to be fed back to the mechanical system. A number of questions arises regarding active damper design, namely how to construct the active damper, what kind of sensors to use and where to place them, how to model the vibration and the mechanical system itself, and, last but not least, how to design the controller. This licentiate thesis deals with the controller design issue. The most widely used controller in active vibration control is the Filtered-X Least Mean Square Controller and it is briefly reviewed in this thesis. The main focus of the thesis is however on another structure, the External Model Controller (EMC). The EMC has much more degrees of freedom than the Filtered-X Controller but lacks performance and robust stability analysis as well reliable design methods. The four papers included in the thesis contribute to bridging this gap.

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