Loudspeaker Diaphragm Excursion Estimation with Adaptive Nonlinear Modeling
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Solution Overview
Problem
Accurately estimating diaphragm excursion in electrodynamic loudspeakers is challenging due to their non-linear nature and time-varying parameters, leading to potential mechanical damage from exceeding maximum excursion limits or unnecessary sound pressure restriction.
Innovation Solution
A method involving a linear adaptive digital loudspeaker model and a non-linear state-space model, where voice coil current and voltage are used to compute non-linearity compensated parameter values, allowing for accurate diaphragm excursion estimation and control by applying a predetermined non-linear function representing the relationship between loudspeaker parameters and variables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a linear loudspeaker model is used for diaphragm excursion estimation, then the device complexity is reduced, but the measurement precision deteriorates due to non-linear effects at high sound pressure levels
Solution Approach 1:
The patent transforms the loudspeaker parameters from constant values to time-varying adaptive parameters. The linear model parameters (mass, compliance, resistance, inductance) are continuously updated to reflect changing operating conditions, allowing the simple linear model structure to capture non-linear behavior through parameter adaptation rather than through complex model structure
Solution Approach 2:
The system uses the loudspeaker's own operating signals (voice coil voltage and current) to automatically update its model parameters. The adaptive algorithm continuously learns from the actual operating conditions without requiring external calibration or complex measurement equipment, enabling the model to self-adjust to non-linear effects
2Device complexity
If loudspeaker parameters are treated as constant, then the device complexity is reduced, but the measurement precision deteriorates due to time-varying parameter effects
Solution Approach 1:
The patent makes the previously static model parameters dynamic and time-varying. The adaptive algorithm continuously updates the loudspeaker parameters based on real-time operating conditions, allowing the model to track changes in mechanical compliance, electrical resistance, and other parameters that naturally vary with temperature, wear, and operating state
Solution Approach 2:
The system implements feedback by using the measured voice coil voltage and current to continuously update the model parameters. The adaptive algorithm processes the operating signals and feeds back updated parameter values to the estimation model, creating a closed-loop system that maintains accuracy despite parameter drift over time
3Measurement precision
If complex non-linear models are used to account for non-linear effects, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
Instead of changing the model structure to complex non-linear forms, the patent maintains a simple linear model structure but changes the parameters from constant to time-varying adaptive values. This approach captures non-linear effects through parameter adaptation while preserving the computational simplicity and structural elegance of linear models
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 improves the accuracy of diaphragm excursion estimation, preventing mechanical damage while maintaining sound quality by accurately limiting diaphragm excursion without requiring complex calibration or excessive computational resources.
Implementation Method 1
applying the audio output signal to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound
Implementation Method 2
The electrodynamic loudspeaker may be utilized for sound reproduction purposes
Data Source
AI summary
A method of estimating diaphragm excursion of an electrodynamic loudspeaker may be performed using audio signals. An audio output signal may be applied to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound. A detected voice coil current and a determined voice coil voltage may be applied to a linear adaptive digital loudspeaker model that has a plurality of adaptive loudspeaker parameters. The parameter values of the adaptive loudspeaker parameters may be computed based on the linear adaptive digital loudspeaker model and applied to a non-linear state-space model of the electrodynamic loudspeaker. For the non-linear state-space model, a predetermined non-linear function may be applied to at least one of the plurality of received parameter values to compute at least one non-linearity compensated parameter value of the adaptive loudspeaker parameters, to determine an instantaneous excursion of the diaphragm.