Active Vibration Noise Control Device Stability
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Solution Overview
Problem
Existing active vibration noise control devices in vehicles fail to maintain effective noise cancellation due to unstable operation in narrow environments, where sound wave interference and reflection cause deep dips in transfer characteristics, leading to decreased noise-canceling effects, as they only consider transfer characteristics from speakers to microphones without accounting for vibration noise characteristics.
Innovation Solution
An active vibration noise control device that generates error signals from microphones to adjust control sounds from multiple speakers, using an adaptive notch filter and filter coefficient updates based on transfer characteristics and vibration noise characteristics to ensure effective noise cancellation, by changing the amplitude and step-size parameters of control signals according to the similarity degree between transfer characteristics and vibration noise characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple speakers are used and speaker paths are switched based on transfer characteristics, then noise-canceling effect is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic switching between multiple speaker paths based on real-time evaluation of transfer characteristics. The system continuously monitors the similarity degree between transfer characteristics and vibration noise characteristics, and dynamically selects or switches speaker paths to maintain optimal noise cancellation performance. This dynamic adaptation resolves the contradiction by enabling reliability improvement through multiple speakers while managing complexity through automated dynamic selection rather than permanent multi-path infrastructure.
Solution Approach 2:
The patent changes the parameter of similarity degree calculation between transfer characteristics and vibration noise characteristics to determine optimal speaker selection. By evaluating and comparing these parameter similarities, the system intelligently selects the most appropriate speaker path without requiring complex manual configuration or permanent activation of all speaker paths, thus improving noise-canceling effect while controlling device complexity.
2Reliability
If gain is increased to compensate for transfer characteristic dips, then noise-canceling effect is improved, but operation stability deteriorates
Solution Approach 1:
The patent performs preliminary evaluation of the similarity degree between transfer characteristics and vibration noise characteristics before executing noise cancellation. By pre-assessing whether the transfer characteristics match the vibration noise characteristics, the system can proactively select appropriate speaker paths or adjust parameters before instability occurs, rather than reactively increasing gain when dips are detected. This preliminary action prevents operation instability while maintaining noise-canceling effect.
Solution Approach 2:
The patent implements feedback mechanisms that continuously monitor the similarity degree between transfer characteristics and vibration noise characteristics. This feedback allows the system to detect potential instability conditions early and adjust speaker selection or parameters accordingly, preventing the need for aggressive gain increases that would compromise operational stability. The feedback loop maintains both noise-canceling effectiveness and operation stability.
Data Source
AI summary
An active vibration noise control device obtains error signals corresponding to a cancellation error between vibration noise and control sounds generated by multiple speakers, from microphone(s), and actively controls the vibration noise. A basic signal generating unit generates a basic signal based on a vibration noise frequency. An adaptive notch filter unit generates control signals provided to each of the multiple speakers by applying a filter coefficient to the basic signal. A reference signal generating unit generates a reference signal from the basic signal based on multiple transfer characteristics from the multiple speakers to the one or more microphones. A filter coefficient updating unit updates the filter coefficient used by the adaptive notch filter unit so as to minimize the error signals. A controlling unit changes amplitude of the control signals of the speakers based on a similarity between the transfer characteristics and characteristics of the vibration noise.