Active Acoustic Control of Conical Bores Through Actuating Boundary Conditions

This paper presents an investigation into control of sealed conical bores. Beginning with an impedance model of the enclosure, frequency domain and state-space models of the system are developed as functions of the geometric and mechanical properties of the cone. A discussion of coupling this acoustic model with the electrical and mechanical dynamics of a permanent magnet speaker are also presented. Using a sample geometry, the accuracy of this coupled model is validated against experimental results, indicating accuracy levels of 1.75% or lower in prediction of resonance frequencies. This paper concludes with a study on applying Linear Quadratic Regulator techniques to this system, relating trade-offs between average pressure and control voltages. The results of our simulations indicate that pressure reductions of 40.5% are attainable with average control voltages of 3.26 volts when subject to low level impulse disturbances, as applied to an example geometry.