Node Localization Using Time Difference of Flight Measurements

Solution Overview

Problem

Distributed sensor networks face challenges in accurately localizing nodes without precise positioning, especially in low-cost and low-power consumption systems, as existing methods like GPS require high timing accuracy and synchronization.

Innovation Solution

The use of time difference of flight measurements between nodes with known locations to determine the location of unknown nodes, reducing the need for precise timing accuracy and synchronization, and employing a mesh network structure for efficient signal transmission and reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GPS or time of flight measurements with precise clock systems are used for localization, then localization accuracy is improved, but system cost and power consumption increase

Engineering Contradiction:

Improvelocalization accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent replaces expensive, power-intensive GPS receivers and precise clock systems with inexpensive, low-power microcontroller units that can be deployed throughout the structure. Each MU acts as a disposable, low-cost localization node that consumes minimal power while collectively providing accurate localization data through the networked TDOA system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces signal propagation time measurements as an intermediary mechanism. Instead of requiring direct GPS signals at each node, the system uses wireless signal transmission times between MUs as intermediaries to calculate positions. This intermediary approach allows accurate localization without requiring precise synchronized clocks at each node.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If GPS or time of flight measurements with precise clock systems are used for localization, then localization accuracy is improved, but system cost increases

Engineering Contradiction:

Improvelocalization accuracyVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive, power-intensive GPS receivers and precise clock systems with inexpensive, low-power microcontroller units that can be deployed throughout the structure. Each MU acts as a disposable, low-cost localization node that consumes minimal power while collectively providing accurate localization data through the networked TDOA system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical/electronic GPS receiver system with a software-based TDOA calculation system running on inexpensive microcontrollers. Instead of relying on GPS hardware and precise clock hardware, the system uses software to measure signal arrival times and calculate positions, dramatically reducing component costs.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If random sensor distribution is used, then system cost is reduced, but localization capability is worsened

Engineering Contradiction:

Improvesystem costVSAvoidlocalization capability

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces signal propagation time measurements as an intermediary mechanism. Instead of requiring direct GPS signals at each node, the system uses wireless signal transmission times between MUs as intermediaries to calculate positions. This intermediary approach allows accurate localization without requiring precise synchronized clocks at each node.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where MUs exchange signal transmission and reception time data, and the central system uses this feedback to calculate positions and potentially refine the localization algorithm. The system processes TDOA measurements from multiple MU pairs to determine accurate positions even with random distribution.

Inventive Principle:

Principle #23Feedback

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 accurate localization of nodes with reduced system cost and power consumption, enabling effective tracking of node positions in large-scale distributed sensor networks.

Implementation Method 1

Localization of nodes whose location is unknown within a network is accomplished by using time difference of flight measurements sent from nodes with known locations

Methodology Applied

Scientific EffectTime difference of flight measurement: Time of Flight

Data Source

PatentUS8102784B1Localization in a network

Publication Date: 2012.01.24 ANALOG DEVICES INT UNLTD CO

AI summary

A system for determining node locations comprises an interface for receiving a first set of measurements at a first set of nodes, the first set of nodes having known locations. The system further comprising an interface for receiving a second set of measurements at a node having an unknown location, and a processor configured for determining a location of the node with unknown location based at least in part on the first set of measurements and the second set of measurements.