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Exploitable results

Reasarch was carried out in order to quantify the performance of an active control system which minimizes structural power input, in comparison with conventional active control methods. The main conclusions derived from the evaluation of the control strategies were as follows; minimization of the sum of the squared velocities on the source structure gives very large reductions in transmitted power at almost all frequencies, but requires a large number of sensors and a control system with a large number of channels; minimization of an estimate of the transmitted power, obtained from only the out-of-plane forces and velocities at the mounting points, can give rise to significant increase in total structural power transmission; cancellation of either the out-of-plane forces or velocities at the mounting points can give good reductions in the total power being transmitted into the receiving structure at most excitation frequencies, but can fail to give adequate control at frequencies for which the controlled system is in resonance; a new active control strategy of minimizing the weighted sum of squared forces and velocities at the mounting points gives reductions in transmitted power which are close to optimal over the whole frequency range. The most important results include: establishment of total power transmission as a criterion for quantifying the performance of active control systems; identification of power circulation as a significant problem in control systems which directly minimize a measured estimate of total power; development of new control strategy which uses an indirect but robust method of achieving reductions in total transmitted power which are close to the optimal; experimental demonstration of prototype active control system on a realistic structure to illustrate these principles; L% comparison of different sensor and actuator technologies and the development of a novel active mount.