Vehicle Noise Cancellation Using Transient Waveform Database
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Solution Overview
Problem
Existing noise cancellation systems in vehicles fail to effectively mitigate transient and steady-state sound deviations caused by disturbances such as exhaust gas recirculation valve operations, A/C Clutch operations, and other automotive system changes, which can be objectionable to vehicle operators and occupants.
Innovation Solution
A noise cancellation system that includes a processor to determine the current operating point and disturbance type, selecting corresponding noise cancellation waveform data from a database to output a noise cancelling waveform to audio transducers, with phase adjustment based on engine crank angle, and using fast Fourier transformation coefficients for efficient noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional noise cancellation systems are used, then steady-state noise can be mitigated, but transient noise deviations caused by disturbances cannot be effectively reduced
Solution Approach 1:
The system dynamically adapts its noise cancellation strategy based on real-time detection of disturbance events. When a transient disturbance is detected (such as EGR valve operation or A/C clutch engagement), the system switches from steady-state cancellation to transient-specific cancellation using pre-stored waveform data corresponding to the detected disturbance type and current operating point, thereby effectively handling both steady-state and transient noise conditions.
Solution Approach 2:
The system changes operational parameters by selecting different noise cancellation waveforms from a database based on the detected disturbance type and current operating point (engine speed, load, temperature). This parameter switching allows the system to optimize noise cancellation for specific transient events rather than using a fixed cancellation strategy.
2Object-affected harmful factors
If real-time noise cancellation is implemented, then noise can be reduced, but system complexity and computational requirements increase
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing noise cancellation waveforms in a database during offline characterization for various disturbance types and operating points. During real-time operation, the controller only needs to detect the disturbance type, identify the current operating point, and retrieve the corresponding pre-computed waveform data, significantly reducing online computational requirements while maintaining effective noise cancellation.
Solution Approach 2:
The system uses copied waveform data from the database rather than generating new cancellation waveforms in real-time. The pre-stored waveform representations are retrieved and applied directly, eliminating the need for complex real-time signal processing and Fourier transformations during actual noise cancellation operation.
3Adaptability or versatility
If comprehensive disturbance coverage is achieved, then all noise sources can be addressed, but data management and system response time are affected
Solution Approach 1:
The noise cancellation database is segmented into distinct sections for different disturbance types (EGR valve, A/C clutch, fuel injector pump, etc.) and operating conditions. This segmentation allows the controller to quickly navigate to and retrieve only the relevant waveform data corresponding to the currently active disturbance, minimizing data retrieval time while maintaining comprehensive coverage of all possible disturbance scenarios.
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
The system effectively reduces undesirable sound deviations by generating tailored noise cancelling waveforms that destructively interfere with disturbance-induced sounds, improving passenger comfort by minimizing objectionable noise variations during transient and steady-state responses.
Implementation Method 1
generating tailored noise cancelling waveforms that destructively interfere with disturbance-induced sounds
Data Source
AI summary
A method for noise cancellation includes monitoring a system for a current operating point, monitoring the system for a predetermined disturbance, and in response to the predetermined disturbance, determining the disturbance to be in one of a transient or steady state response period. A set of data is selected corresponding to the current operating point of the system, the disturbance, and the response period from a database containing predetermined noise cancellation waveform data. A noise cancelling waveform is output to audio transducers based upon the selected set of data.