When you’re driving down the highway, the last thing you want to hear is unexpected engine noises. These noises, including buzzes, squeaks, and rattles (BSRs), make drivers nervous. Before a car ever hits the road, auto manufacturers perform rigorous tests to remove annoying BSRs. However, sometimes it’s hard to tell where the noise is coming from. To address this issue, Hyundai developed a portable system that uses acoustic beamforming to identify and display noise sources in real time.
Acoustic beamforming involves mapping noise sources using an acoustical array. It determines the direction of the sound by the time delays that occur as the sound passes over an array of microphones such as a sound camera. (A sound camera turns sound into color, similar to the way a thermal camera visualizes temperature.) Several commercial beamforming devices convert the signals of the array into noise magnitude contours. Voila—you can see the noise overlaid on an image of the engine.
The first systems Hyundai developed used analog microphones. They acquired data using the NI 9234 dynamic signal acquisition (DSA) module in an NI CompactDAQ system for the 30-channel version and they used the NI PXIe-4497 DSA module for the 48-channel version. They also developed a sound camera application in LabVIEW with the NI Sound and Vibration Measurement Suite that included sound quality measurements for real-time display.
They then ported the application using the LabVIEW FPGA Module to convert the computationally intensive beamforming algorithms to run on an NI Single-Board RIO FPGA, which further helped with size, cost, and portability of the system. This also made it possible to integrate signal conditioning, data acquisition, filtering, and beamforming into a single chip to connect the acquisition hardware directly with the processing unit in the FPGA.
Hyundai mounted all the sensors in the main body with integrated cabling, which reduced size by 60 percent and reduced weight by 70 percent versus the previous system. In the end, the system weighs less than five pounds and is being used to test several new luxury models such as the Hyundai Genesis.