Use of active structural control for isolation

摘要

Active structural control using the ACX QuickPack~R piezoelectric strain actuators has been proven to be an effective method for controlling vibration. However there are structures where the optimal strain actuator location is either inaccessible or undesirable. Under such circumstances, a solution can be an active isolation system where strain actuators are placed along the direct transmission path of the vibration. The feasibility of an active isolation system was demonstrated using a cantilevered beam with a tip mass. Vertical acceleration at the tip was used as the performance metric, and a force near the clamp as the disturbance source. Thin aluminum flexures sandwiched by QuickPack strain actuators were placed between the beam end and the mass to isolate the mass from the beam. A finite element model was built and a state-space representation derived for the transmissibility between disturbance and performance to optimize the flexures and actuators, as well as to predict performance. Once the system was built, transfer functions were taken and a PPF controller was implemented. The amount of vibration transmitted to the mass was reduced by 22 dB overall, with a 5 dB reduction due to the passive isolation effects, and 17 dB due to the active control.