Loudspeaker Excursion Prediction Using Adaptive Impedance Modeling
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Solution Overview
Problem
Existing loudspeaker models are unreliable when there are discrepancies between expected and actual loudspeaker/enclosure characteristics due to manufacturing tolerances or mechanical damage, leading to inaccurate diaphragm displacement predictions.
Innovation Solution
A time-domain estimation method that calculates the input-voltage-to-excursion transfer function using impedance or admittance functions, delta function, and force factor, allowing for adaptive filtering and robust noise handling without requiring prior knowledge of the enclosure type, thus maintaining model validity across different configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If parametric loudspeaker models with fixed enclosure assumptions are used, then the model structure is simple and easy to implement, but the model becomes invalid when there are defects or changes in the loudspeaker/enclosure characteristics
Solution Approach 1:
The patent implements dynamic adaptation of the loudspeaker model by continuously updating model parameters based on real-time measurements of electrical impedance, mechanical resonance frequency, and acoustic output. This allows the model to transition from static parametric assumptions to dynamic adaptive modeling, maintaining validity even when enclosure characteristics change due to defects or environmental factors.
Solution Approach 2:
The system performs self-diagnosis and self-adjustment by monitoring its own performance parameters (impedance, resonance frequency, acoustic output) and automatically updating the model parameters without external intervention. This self-service mechanism ensures the model remains valid despite changes in loudspeaker or enclosure characteristics.
2Reliability
If variable cut-off filters with feedforward or feedback control loops are used to limit diaphragm displacement, then loudspeaker protection is improved, but the system complexity and computational requirements increase
Solution Approach 1:
The patent calculates the input-voltage-to-excursion transfer function in advance using pre-measured or pre-stored parameters (electrical impedance, force factor, resonance frequency, Q-factor). This preliminary calculation allows the system to predict diaphragm excursion without requiring complex real-time feedback control loops, reducing system complexity while maintaining protection capabilities.
Solution Approach 2:
The patent replaces complex mechanical feedback measurement systems with electrical parameter measurements (impedance, current, voltage) that are easier to obtain and process. By substituting direct mechanical displacement sensing with electrical parameter-based prediction, the system achieves protection with reduced complexity.
3Reliability
If time-domain estimation methods are used to calculate the input-voltage-to-excursion transfer function, then the model remains valid for different enclosure configurations and is robust to noise, but the computational processing requirements increase
Solution Approach 1:
The patent changes the approach from frequency-domain parameter estimation to time-domain parameter estimation. By measuring electrical impedance and acoustic output in the time domain and deriving the transfer function directly from time-domain responses, the system achieves robustness to noise and enclosure variations without requiring complex frequency-domain transformations, balancing computational requirements with reliability.
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 provides a robust and adaptable method for predicting diaphragm displacement and controlling loudspeaker output, ensuring accurate protection and acoustic signal processing even with production defects or mechanical damage, and is applicable to complex enclosure designs without needing parametric assumptions.
Implementation Method 1
an important cause of loudspeaker failures is a mechanical defect that arises when the loudspeaker diaphragm is displaced beyond a certain limit
Implementation Method 2
the loudspeaker/enclosure configuration corresponds to that expected from the design
Data Source
AI summary
A loudspeaker control system is disclosed. The loudspeaker control system includes a loudspeaker, a sensor for measuring a voltage and current and a processor. The processor is adapted to calculate an input-voltage-to-excursion transfer function over time from an admittance function, blocked electrical impedance and force factor, use the input-voltage-to-excursion transfer function over time to predict an excursion and use the excursion to control audio processing of the loudspeaker.