MIMO DFAT System Real-Time Control via Magnitude Updates
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Solution Overview
Problem
Current multiple-input-multiple-output (MIMO) direct field acoustic test (DFAT) systems face limitations in real-time control performance due to geometrically increasing calculations and hardware constraints, particularly limiting frequency control to below 2 kHz, number of control inputs, and outputs.
Innovation Solution
Implementing a MIMO DFAT system with simplified reference spectrum data and focusing on magnitude updates of drive signals, using equal numbers of control inputs and outputs, and suppressing phase and coherence calculations to enable faster real-time updates, extending the controlled frequency range above 2 kHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple separately controllable outputs are used to drive separate groups of acoustical transducers with multiple microphones for control inputs, then the control precision and spatial uniformity of the acoustic field are improved, but the calculation complexity and hardware requirements increase geometrically
Solution Approach 1:
The patent segments the MIMO system into multiple independently controllable output channels, each driving a separate group of acoustical transducers. This segmentation allows the complex acoustic field control problem to be divided into manageable sub-problems, where each output channel can be controlled independently while contributing to the overall spatial uniformity and control precision of the acoustic field.
Solution Approach 2:
The patent introduces multiple microphones as intermediary sensing elements that measure the acoustic field at different locations and provide feedback to the control system. These microphones act as mediators between the acoustical transducers and the control processor, enabling precise measurement and control of the acoustic field characteristics without requiring direct complex calculations between all transducer elements.
2Measurement precision
If multiple microphones are used to provide separate control inputs for real-time control, then the control accuracy is improved, but the number of calculations required increases geometrically
Solution Approach 1:
The patent performs preliminary measurement and characterization of the acoustic transfer functions between each transducer group and each microphone location before real-time control operation. This preliminary action creates a lookup table or pre-computed model that can be used during real-time operation, allowing the control system to achieve high accuracy without performing geometrically increasing calculations during the actual test.
Solution Approach 2:
The patent uses multiple microphones to provide comprehensive control input coverage, which would ideally provide complete control accuracy. However, the system implements partial action by using a subset of the available microphone data and pre-computed transfer functions, achieving sufficient control accuracy while maintaining real-time processing capability and avoiding the full geometric increase in calculation complexity.
3Measurement precision
If full real-time control calculations are performed for all control inputs and outputs, then the control accuracy is maintained, but the maximum controllable frequency is limited to below 2 kHz
Solution Approach 1:
The patent performs preliminary measurement of the acoustic transfer functions and system characteristics before real-time control operation. By pre-characterizing the system response across the full frequency range, the control system can operate at higher frequencies (above 2 kHz) without performing complete real-time calculations for all control inputs and outputs, thus maintaining control accuracy while extending the maximum controllable frequency.
Solution Approach 2:
The patent changes the control parameters by using pre-computed transfer functions and magnitude updates instead of performing complete real-time control calculations at each frequency point. This parameter change allows the system to operate at higher frequencies where complete real-time control would be computationally prohibitive, while still maintaining sufficient control accuracy for acoustic vibration testing.
4Measurement precision
If the system updates all drive signal parameters in real-time, then the control precision is maintained, but the update speed is insufficient for frequencies above 2 kHz
Solution Approach 1:
The patent extracts and updates only the magnitude component of the drive signals in real-time, while the phase information is derived from pre-computed transfer functions. This extraction of the essential magnitude parameter for real-time updates reduces the computational burden and update time, enabling the system to maintain control precision while achieving update speeds sufficient for frequencies above 2 kHz.
Solution Approach 2:
The patent implements partial action by updating only the magnitude component of the drive signals rather than all parameters (magnitude and phase). This partial update approach maintains sufficient control precision for acoustic vibration testing while significantly reducing the update time, allowing the system to operate at higher frequencies where complete parameter updates would be too slow.
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 allows for more accurate and faster real-time control of acoustic fields, enabling frequency control up to substantially above 2 kHz and potentially above 10 kHz in some configurations, enhancing the system's performance and flexibility.
Implementation Method 1
multiple groups of separately driven acoustical transducers
Implementation Method 2
at least four microphones are employed to measure the acoustic field at four separate locations and to provide preferably at least four control input signals
Data Source
AI summary
A direct field acoustic testing system includes at least one control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and at least four acoustic transducer groups operatively coupled to the controller such that each transducer is separately controllable by the controller such that a separate output signal is received by each transducer from the controller. A setup signal is applied to each of the acoustical transducers. The acoustic output of each of the acoustical transducers is monitored using the at least one control microphone. Assumptions regarding the relationship between the acoustic fields measured by the control microphones are made to enable the controller to reduce the number of calculations needed to compute error functions and corrected drive signals to be applied to the acoustic transducer groups.