Theoretical models of the various parts of a system with multiple active mounts have been developed which includes a flexible receiving structure and distributed active mounts, and these models can be connected together to produce an overall theoretical description of a realistic active isolation system. Total transmitted power has been found to be an excellent criterion to quantify the effect of various control strategies in this model in which the contributions to the transmitted power in the various degrees of freedom can be clearly understood. It has also been found, however, that an active control system which minimises a practical estimate of transmitted power, calculated from the product of the axial forces and velocities under the mounts, can give a very poor performance in terms of reducing the total transmitted power, and can even increase it under some circumstances. Such a control system was also found to be very sensitive to measurement errors and the presence of flanking paths, which give rise to the phenomena of power circulation. A more practical control strategy appears to be to minimise the weighted sum of squared forces and velocities below the mounts, which gives near-optimal performance in simulations. These theoretical results are supported by experiments with a real-time control systems.
The proposed research will investigate the ways in which measurements of structural power transmission can be used to actively control vibration. Active control has potential applications in reducing vibration in road vehicles, domestic appliances and fixed and rotary wing aircraft. The advantage of active control in these applications is that vibration control can generally be achieved more efficiently and with less added mass than with the use of conventional, passive, solutions. Active control has traditionally been achieved by the use of a large number of sensors to continuously sample the vibration over the whole structure, and the adjustment of the inputs to the secondary sources to minimise this measure of the vibration. Recent theoretical work at both ISVR and CETIM has demonstrated that a similar objective can be the primary and secondary sources. The aim of this research is to build on this theoretical work to investigate the physical effects and control algorithms required for power minimisation in a variety of structures. This research is timely because of the rapid developments taking place in the techniques of structural power measurement, and the new generation of sensors and actuators which are now becoming available. The project would culminate in a practical demonstration of active vibration control by power input minimisation.
The project builds on the established strength in active sound and vibration control at ISVR in the measurement of structural power transmission at CETIM, ISVR and TUD.
Funding SchemeCSC - Cost-sharing contracts