Acoustic Localization System Position Accuracy
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Solution Overview
Problem
Conventional marking units face challenges in conserving energy while maintaining the ability to distinguish between power-saving mode and loss or theft, as they cannot switch off their transmitter and receiver without creating ambiguity.
Innovation Solution
The marking unit operates in a synchronous mode, transmitting telegrams at predetermined times based on a transmission schedule and using a motion sensor to determine its movement profile, adapting transmission behavior to the estimated base unit, and switching to search mode if communication fails or the profile is unknown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If acoustic waves are emitted to detect objects, then object detection capability is improved, but position accuracy deteriorates due to multipath effects and noise
Solution Approach 1:
The patent segments the acoustic signal processing into multiple independent components: cross-power spectral density estimation, coherence calculation, and time-delay estimation. This segmentation allows each component to be optimized independently, improving overall position accuracy while maintaining detection capability in noisy environments with multipath effects
Solution Approach 2:
The patent introduces coherence as an intermediary metric between the acoustic signals and position estimation. By using coherence to filter out incoherent signals (noise and multipath reflections) before final position calculation, the system achieves better position accuracy while maintaining robust object detection
2Measurement precision
If multiple acoustic sensors are deployed to improve position accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent designs each acoustic sensor to perform multiple functions: detecting acoustic waves from objects, estimating cross-power spectral density, calculating coherence, and determining time delays. This multi-functionality allows the system to achieve high position accuracy with fewer sensors, reducing overall device complexity while maintaining measurement precision
Solution Approach 2:
The system uses the acoustic signals themselves to generate the reference cross-power spectral density estimates through mutual coherence calculation between sensor pairs. This self-service approach eliminates the need for external calibration signals or complex reference systems, achieving high precision with simpler device architecture
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 minimizes energy consumption by only transmitting when near a base unit and efficiently detects loss or theft by adjusting transmission frequency and mode, ensuring reliable location tracking without continuous operation.
Implementation Method 1
a first acoustic sensor of a group of acoustic sensors arranged in a predetermined geometric configuration, wherein the first acoustic sensor is configured to detect an acoustic wave emitted by the object
Data Source
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AI summary
The invention relates to a method (45) for localizing a marking unit (11) of an object (15) by means of at least one base unit (12, 13, 14), wherein during at least one predetermined transmission time (T), the marking unit (11) emits a transmission message (20) and operates a receiving device (32) in order to receive a response message (21) from one of the at least one base unit (12, 13, 14) as a response to the relevant transmission message (20). The invention provides for the marking unit (11) to define the at least one transmission time (T) in a synchronous mode (M1) by means of a predetermined transmission plan (24) assigned to the at least one base unit (12, 13, 14).