Vehicle Road Noise Control via Beamforming Microphone Array
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Solution Overview
Problem
Existing active road noise control systems face challenges in efficiently reducing road noise experienced by cabin occupants in vehicles, particularly due to the complexity of noise sensor arrangements required to observe road noise signals from moving parts like rolling wheels.
Innovation Solution
An active road noise control system utilizing a noise sensing microphone array with at least three microphones arranged in a line or plane around a wheel arch, beamformers to generate reference signals with specific sensitivity characteristics, and error microphones to provide adaptive noise reducing signals, which are then used by loudspeakers to generate noise reducing sound at listening positions within the vehicle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex noise sensor arrangements are used throughout the vehicle structure to observe road noise signals, then measurement precision of road noise is improved, but device complexity increases
Solution Approach 1:
The patent extracts the noise sensing function from multiple distributed sensors throughout the vehicle structure and concentrates it into a single microphone array located at the wheel arch. This extraction approach captures road noise signals effectively while avoiding the complexity of multiple sensors distributed across the vehicle structure.
Solution Approach 2:
The patent introduces beamforming technology as an intermediary signal processing method that enables a single microphone array to achieve the measurement capability of multiple distributed sensors. The beamforming algorithm processes signals from the microphone array to selectively capture noise from specific directions (wheel and hub), effectively acting as a virtual sensor array without requiring physical distribution of multiple sensors.
2Measurement precision
If multiple distributed sensors are used to capture road noise from different sources, then measurement precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent extracts the noise sensing function from multiple distributed sensors throughout the vehicle structure and concentrates it into a single microphone array located at the wheel arch. This extraction approach captures road noise signals effectively while avoiding the complexity of multiple sensors distributed across the vehicle structure.
3Device complexity
If a single microphone array is used instead of multiple distributed sensors, then device complexity is reduced, but measurement precision of road noise sources deteriorates
Solution Approach 1:
The patent introduces beamforming technology as an intermediary signal processing method that enables a single microphone array to achieve the measurement capability of multiple distributed sensors. The beamforming algorithm processes signals from the microphone array to selectively capture noise from specific directions (wheel and hub), effectively acting as a virtual sensor array without requiring physical distribution of multiple sensors.
Solution Approach 2:
The patent changes the operational parameters of the single microphone array by applying beamforming processing that dynamically adjusts the sensitivity characteristic to have two main lobes directed at different noise sources. This parameter change in the signal processing domain compensates for the physical limitation of having a single array location, enabling precise source separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy and frequency range of road noise control, creating quiet zones around passengers and improving overall noise reduction performance without modifying the vehicle's structure.
Implementation Method 1
one or two beamformers configured to process the multiplicity of noise sense signals to generate a first reference signal and a second reference signal, and to provide, in connection with the noise sensing microphone array, a sensitivity characteristic that comprises two main lobes
Implementation Method 2
a first loudspeaker arrangement disposed in an interior of the vehicle and configured to generate, from the noise reducing signal, noise reducing sound at a listening position
Implementation Method 3
a noise sensing microphone array configured to generate a multiplicity of noise sense signals representative of road noise originating from road noise sources
Data Source
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AI summary
An active road noise control system method for a vehicle includes picking up noise at a multiplicity of positions in or on the vehicle and generating a multiplicity of noise sense signals representative of road noise originating from a road noise source in or at the vehicle, and processing, according to a beamforming scheme, the multiplicity of noise sense signals to generate a reference signal and to provide a sensitivity characteristic for picking up the noise that comprises one main lobe directed to the road noise source. The system and method further includes iteratively and adaptively processing the reference signal to provide a noise reducing signal, and generating at one or more positions in an interior of the vehicle, from the noise reducing signal, noise reducing sound at a listening position in the interior of the vehicle.