Turbocharger Rotational Speed Estimation via Acoustic Measurements

This paper deals with the estimation of the turbocharger rotating speed via the numerical processing of the overall sound emissions acquired via a microphone placed under the vehicle hood. As a matter of fact, this kind of signals represents an extremely rich information source about the operating conditions of all the noisy powertrain subsystems. The core of the scheme is represented by an adaptive Frequency Locked-Loop (FLL) filter that is properly designed so as to extract useful frequency content from the acquired audio signals. The whole architecture, requiring the use of a single microphone only, can be considered innovative and low-cost for automotive applications. Experimental outcomes demonstrate that the approach is ready to be introduced in the Engine Control Unit (ECU) in order to implement suitable strategies for turbocharger control.