Wavelet analysis for structure-borne sound generating sensor in injection molding

For a recently developed novel acoustic sensor for injection molding a signal processing unit was developed. Sensor elements inside the mold generate structure-borne sound in order to detect the filling level of the cavities. One acceleration sensor picks up the vibrations on the surface of the mold. The task of signal processing is to identify the source of the sound and to find the instant of time when each of the cavities has a defined filling status. This information is important if using process control to obtain an optimal coincidence of the filling times. For fast prototyping, the BeagleBoard as a popular low-cost single-board computer was chosen. Analysis and discrimination of the sensor signals was done with a wavelet filter bank. A scientific tool suite with cross-development facility leads to short development time and numerically efficient code.