Wireless Terminal Position Estimation Using Posture-Corrected Signal Strength

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Solution Overview

Problem

Existing indoor position measurement techniques for wireless terminals in home energy management systems are inaccurate due to variations in receiving electric field strength caused by terminal posture and antenna directivity, leading to incorrect distance estimation and position calculation.

Innovation Solution

A position estimation device that includes a distance estimation unit, a position estimation unit, and a correction unit to accurately determine the current position of a wireless terminal by using receiving strength from multiple base stations, correcting distance information based on acceleration, direction, and posture, and specifying the positional relationship between the terminal, base stations, and users.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If distance estimation is performed using receiving strength of signals from base stations, then position estimation can be achieved, but measurement precision deteriorates due to variations in receiving strength caused by terminal posture and antenna directivity

Engineering Contradiction:

Improveposition estimation accuracyVSAvoidreceiving strength consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the parameter used for distance estimation from raw receiving strength to a corrected value that accounts for terminal posture and antenna directivity. The correction unit adjusts the receiving strength based on acceleration data (to determine posture) and direction data (to determine antenna orientation), thereby compensating for variations caused by these factors and improving measurement precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a feedback mechanism where the estimated position and terminal posture information are used to correct the receiving strength measurement. The correction unit uses the relationship between terminal orientation and antenna directivity to adjust the receiving strength, creating a closed-loop system that improves the reliability of distance estimation

Inventive Principle:

Principle #23Feedback

2Measurement precision

If simple distance estimation based on receiving strength is used, then device complexity is reduced, but measurement precision worsens due to uncorrected posture and orientation effects

Engineering Contradiction:

Improvedistance estimation accuracyVSAvoidposition estimation system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the existing acceleration sensor and direction sensor serve multiple functions: they are used for terminal posture detection (original function) and also for position estimation correction (new function). By utilizing the same sensors for both purposes, the patent improves measurement precision without significantly increasing device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent enables the terminal to self-correct its position estimation using its own built-in sensors (acceleration and direction sensors). The terminal independently determines its posture and orientation, then uses this information to correct the receiving strength measurement, eliminating the need for external correction systems

Inventive Principle:

Principle #25Self-service

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

The solution enhances the accuracy of wireless terminal position estimation by accounting for posture and environmental factors, improving the precision of distance calculations and reducing signal attenuation errors.

Implementation Method 1

a receiving strength of a signal received by the wireless terminal from each of a plurality of base stations communicating with the wireless terminal

Methodology Applied

Scientific EffectRadio wave propagation and signal attenuation: Absorption (EM radiation)

Implementation Method 2

the receiving electric field strength of the signal transmitted from the base station varies depending on the terminal posture with respect to the base station due to an influence of antenna arrangement or antenna directivity in the wireless terminal

Methodology Applied

Scientific EffectAntenna directivity:

Data Source

PatentUS9372254B2Position estimation device, position estimation method, program and integrated circuit

Publication Date: 2016.06.21 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

A position estimation device which includes: a distance estimation unit which estimates, using a receiving strength of a signal received by a wireless terminal from each of a plurality of base stations communicating with the wireless terminal, distance information indicating a distance from the base station to the wireless terminal; a position estimation unit which estimates a first position to be a current position of the wireless terminal using base station information indicating a position of the base station and the estimated distance information; and a correction unit which corrects the distance information based on an acceleration and a direction of the wireless terminal, the estimated first position, and the base station information. The position estimation unit further estimates a second position to be a current position of the wireless terminal using the base station information and the corrected distance information.