Comparison of several strategies in the active structural acoustic control using structural strain measurements

Two Optimized approaches are herein proposed to lighten the real-time computation of the radiated acoustic power from planar structures using discrete strain measurements. These approaches are compared to a reference approach involving finite differences reconstruction of the displacement field from the strain held. The first optimized approach allows the direct calculation of the radiated acoustic power from the discrete strain field while the second optimized approach employs an accelerated evaluation of the radiated acoustic power based on a wavelet transform of the displacement field. The evaluation of the radiated acoustic power from discrete strain values is experimentally assessed using the reference finite differences approach and both optimized approaches. Piezoelectric film (PVDF) strain sensors are used for this validation as well as a feedforward filtered-X LMS controller. Details on the real-time implementation of the cost functions are presented, especially on the off-line adaptation of the control filter. Formal comparisons using acoustic and vibration measurements are presented to better illustrate the control performance and mechanism of the different approaches. Experimental results serve to demonstrate the interest of using the optimized approaches as compared to the reference approach and it is shown that a significant gain in computational burden can be obtained using the proposed optimized approaches without sacrificing the control performance. (C) 2000 Academic Press.