Acoustics

Through the use of specific electronic technologies, the sound emitted by the various mechanical moving organs of a vehicle can be used to improve the overall performances. 

The development of more sophisticated control functions, based on the listening of the emitted sound and on its processing through “Signal Processing” algorithms for the purpose of extracting all the typical and distinctive information of the phenomenon to be controlled has found several applications in the automotive and industrial sector.

Magneti Marelli has developed a Smart Acoustic platform consisting of modular electronics that includes a microphone sensor with basic functions such as:

• Management with optimized signal processing algorithms, in the realm of microphone signal frequencies
• Extraction of acoustic information and reconstruction of engineering information requested to carry out the desired control function
• Communication of engineering parameters reconstructed by the microphone signal towards external control electronics. Communication is supported through CAN or LIN protocols, either one or the other.

The Smart Acoustic platform is available in two versions:

• Smart Acoustic Sensor (SAS):   dedicated to the management of the acoustic signal and to the transmission of the reconstructed acoustic and engineering information to other electronics assembled on the vehicle
• Smart Acoustic Sensor/Actuator (SASA):  carries out the same function as the Smart Acoustic Sensor but also offers the possibility to carry out actuations by closing the control loop locally to the same acoustic platform.

The following applications have been developed so far by Magneti Marelli through the use of the acoustic platform:

• Detection and control of knocking noise (Knock Control)
• Detection and diagnostics of misfires (Misfire detection)
• Detection of Turbocharger revolutions on turbocharged vehicles with improved turbocharger control performances (protection against overspeeds, efficiency optimization)
• Estimate of ethanol percentage contained in “green” fuels and optimization of engine performances according to the detected percentage

The advantages derived from the use of acoustics for the aforementioned applications are tied to an overall increase in system performances as well as to optimal management of system costs based on the use of acoustic information as a “virtual sensor” that can be used by various engine control strategies.