Acoustic Echo Room Shape Reconstruction and Self-Localization
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Solution Overview
Problem
Existing indoor localization techniques require pre-established infrastructure and fail to provide accurate location information in environments without functioning infrastructure, such as during natural disasters, due to issues like microwave attenuation and multi-path propagation.
Innovation Solution
A method using a single mobile device equipped with a loudspeaker and microphone to emit and receive acoustic echoes, allowing for simultaneous room shape reconstruction and self-localization without external infrastructure, utilizing a chirp signal and motion sensors to determine distances and reconstruct 2-D convex polygonal room shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite-based GPS is used for outdoor localization, then localization accuracy and coverage are improved, but the system becomes vulnerable to microwave attenuation and multi-path propagation in indoor environments
Solution Approach 1:
The patent replaces electromagnetic wave-based GPS with acoustic wave-based localization. The mobile device emits acoustic signals and measures echoes to determine position, substituting the mechanical/acoustic measurement system for the electromagnetic GPS system. This resolves the contradiction by using a different physical domain (acoustics instead of electromagnetics) that is less susceptible to building material attenuation and multi-path effects.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary medium for localization. Instead of directly using electromagnetic waves from satellites, the system uses acoustic echoes as an intermediate carrier to convey position information. The acoustic waves interact with the environment differently (reflecting off surfaces) compared to electromagnetic waves, providing a complementary approach that overcomes GPS limitations in indoor settings.
2Measurement precision
If existing indoor localization techniques (WiFi, Bluetooth, UWB, LED) are used, then localization is achieved, but the system requires pre-established infrastructure and fixed anchor nodes
Solution Approach 1:
The patent implements self-service localization where the mobile device itself performs both the signal emission and reception functions. The device uses its own built-in loudspeaker and microphone to generate and detect acoustic echoes, eliminating the need for external anchor nodes or infrastructure. The mobile device autonomously measures distances to walls and reconstructs the room shape, serving its own localization needs without relying on pre-deployed systems.
Solution Approach 2:
The patent makes the mobile device universal by enabling it to perform multiple functions: acoustic signal emission, echo reception, distance measurement, room shape reconstruction, and self-localization. This multi-functionality eliminates the need for separate specialized infrastructure components, allowing any mobile device to serve as a self-contained localization system without requiring external anchors or dedicated hardware.
3Device complexity
If acoustic echoes are used for localization, then infrastructure requirements are reduced, but the system must handle complex echo processing and noise interference
Solution Approach 1:
The patent employs periodic action by using repeated acoustic emissions at different locations and times. The mobile device emits signals at multiple positions along a trajectory, creating a series of echoes that can be processed together. This temporal and spatial repetition allows the system to distinguish genuine echo patterns from noise through consistency analysis, improving detection reliability without requiring complex single-shot processing.
Solution Approach 2:
The patent applies preliminary action by first reconstructing the room shape using acoustic echoes before performing localization. The system pre-processes the environmental map by identifying walls and boundaries from echo data, creating a simplified geometric representation of the space. This preliminary room shape reconstruction provides a framework that guides subsequent localization measurements, making the overall system more robust to noise and measurement errors.
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
Enables autonomous room shape recovery and self-localization in enclosed spaces without pre-existing infrastructure, demonstrating effective SLAM in 2-D convex polygonal rooms with high accuracy and robustness against noise.
Implementation Method 1
a loudspeaker capable of emitting a predetermined sound
Implementation Method 2
receive a series of echoes of the predetermined sound when emitted by the loudspeaker
Implementation Method 3
Motion sensor assisted room shape reconstruction and self-localization
Data Source
AI summary
Simultaneous 2-D room shape reconstruction and self-localization is accomplished using no pre-established infrastructure. A mobile device with co-located microphone and loudspeaker is used to collect echoes reflected by the walls. The system uniquely recovers arbitrary 2-D convex room shape as well as the position of mobile device 10 by collecting and processing distances between three consecutive measurement points as well as acoustic echoes from the device. A practical algorithm for room shape reconstruction and self-localization in the presence of noise and higher order echoes is proposed. Experimental results are provided to demonstrate the effectiveness of the approach.