Automotive MEMS accelerometer enhances vehicle acoustics
A vibration sensor, the AIS25BA, is optimised for sensing road noise and related vibration to enable quieter in-vehicle cabins and eliminate road noise, said STMicroelectronics.
The sensor is claimed to be a best-in-class automotive MEMS accelerometer for accuracy in controlling and quieting in-cabin acoustic environment.
The sensor can enable more acoustic cars with road noise cancellation (RNC) through active noise control (ANC) techniques.
Cars have traditionally been defined by engine performance, exterior design and powertrains, but drivers and passengers are increasingly focused on comfort. EVs are intrinsically less noisy than internal combustion engine (ICE) cars, which has led to car makers to focus on lowering in-cabin noise due to wheel or vibration for a quieter ambient environment.
Noise cancellation algorithms, working with an array of sensors installed throughout the vehicle, measure the ambient sounds, and eliminate vibration using noise-cancelling waveforms that act as anti-vibration (cancelling) sounds.
ST has leveraged its competencies in MEMS ICs to give the AIS25BA characteristics for enhancing RNC system accuracy. The sensor has the lowest electrical noise in the market, claimed ST, which helps vehicle engineers achieve the calmest possible in-car environment. It also has the fast response / low latency needed by the RNC system to calculate corrective waveforms in real-time as well as wide bandwidth to capture disturbances across the full spectrum of sound frequency relevant for the application. The sensor’s wide temperature range and mechanical robustness allows placement in the harshest places of today’s vehicles: near the engine or electric drive as well as close to wheels and suspension.
ST’s AIS25BA three-axis accelerometer is engineered to prioritise RNC system accuracy. At 30 micro g / √Hz in X and Y axes and 50 micro g / √Hz in the Z axis, it has extremely low noise density, which is up to 58 per cent better than the closest competing alternative, according to ST.
Frequency response extends to two and hence covers all the spectrum relevant for in-car noise cancellation. Similarly, the total sensor latency of 266 microseconds is engineered for leaving the system plenty of time to generate noise-cancellation signals in real-time.
The sensor has a time-division multiplex (TDM) digital interface that enables the system to synchronise the outputs from multiple accelerometers installed to measure vibrations throughout the vehicle. The audio-friendly interface also allows easy connection to other types of data buses widely adopted in automotive. The full-scale measurement range is selectable up to ±7.7g, providing a margin with respect to the intense vibrations typical of the application. The supply voltage range is 1.71 to 1.99V.
The AIS25BA is compliant with AEC-Q100 and is available now in a 14-lead 2.5 x 2.5 x 0.86mm LGA package.
Picture credit: Renault Arkana E-Tech
