The paper introduces a new design of a platform mechanism with 6 DOF. The platform is supported on three active legs, each equipped with two rotating drives. The mechanism can be used in active vibration control systems. The values of drive angular velocities are precisely controlled, so that the transmission of the base vibrations onto the platform could be minimal. The values of drive torques to be generated are determined. The mechanism was modelled using the Working Model® 30. The effects of active vibration control are also presented.

A gyroscopic rotor exposed to unbalance is studied and controlled with an active piezoelectrical bearing. A model is required in order to design a suited controller. Due to the lack of related publications utilizing piezoelectrical bearings and obtaining a modal model purely exploiting experimental modal analysis, this paper reveals a method to receive a modal model of a gyroscopic rotor system with an active piezoelectrical bearing. The properties of the retrieved model are then incorporated into the design of an originally model-free control approach for unbalance vibration elimination, which consists of a simple feedback control and an adaptive feedforward control. After the discussion on the limitations of the model-free control, a modified controller using the priorly identified modal model is implemented on an elementary rotor test-rig comparing its performance to the original model-free controller.

A gyroscopic rotor exposed to unbalance and internal damping is controlled with an active piezoelectrical bearing in this paper. The used rotor test-rig is modelled using an FEM approach. The present gyroscopic effects are then used to derive a control strategy which only requires a single piezo actuator, while regular active piezoelectric bearings require two. Using only one actuator generates an excitation which contains an equal amount of forward and backward whirl vibrations. Both parts are differently amplified by the rotor system due to gyroscopic effects, which cause speed-dependent different eigenfrequencies for forward and backward whirl resonances. This facilitates eliminating resonances and stabilize the rotor system with only one actuator but requires two sensors. The control approach is validated with experiments on a rotor test-rig and compared to a control which uses both actuators.

It is possible to enhance acoustic isolation of the device from the environment by appropriately controlling vibration of a device casing. Sound insulation efficiency of this technique for a rigid casing was confirmed by the authors in previous publications. In this paper, a light-weight casing is investigated, where vibrational couplings between walls are much greater due to lack of a rigid frame. A laboratory setup is described in details. The influence of the cross-paths on successful global noise reduction is considered. Multiple vibration actuators are installed on each of the casing walls. An adaptive control strategy based on the Least Mean Square (LMS) algorithm is used to update control filter parameters. Obtained results are reported, discussed, and conclusions for future research are drawn.

Successful implementation of an active vibration control system is strictly correlated to the exact knowledge of the dynamic behavior of the system, of the excitation level and spectra and of the sensor and actuator’s specification. Only the correct management of these aspects may guarantee the correct choice of the control strategy and the relative performance. Within this paper, some preliminary activities aimed at the creation of a structurally simple, cheap and easily replaceable active control systems for metal panels are discussed. The final future aim is to control and to reduce noise, produced by vibrations of metal panels of the body of a car. The paper is focused on two points. The first one is the realization of an electronic circuit for Synchronized Shunted Switch Architecture (SSSA) with the right dimensioning of the components to control the proposed test article, represented by a rectangular aluminum plate. The second one is a preliminary experimental study on the test article, in controlled laboratory conditions, to compare performances of two possible control approach: SSSA and a feed-forward control approach. This comparison would contribute to the future choice of the most suitable control architecture for the specific attenuation of structure-born noise related to an automotive floor structure under deterministic (engine and road-tyre interaction) and stochastic (road-tyre interaction and aerodynamic) forcing actions.