Indoor Positioning via Fixed Station Placement and Insulating Spacers
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Solution Overview
Problem
Existing position estimation systems for mobile objects in buildings face challenges in achieving high accuracy due to multipathing effects, which affect the correspondence between signal strength and distance, leading to inaccurate position estimation.
Innovation Solution
The system includes multiple fixed stations installed at specific positions within a building, such as ceilings, walls, and equipment, with a calculator estimating the mobile object's position based on signal strength measurements. Each station is positioned to be within a predetermined distance from the mobile object when it is directly below, and uses a radio signal transmitter on the mobile object to reduce multipathing by blocking downward radiation, allowing for accurate position estimation using signal strength thresholds and trilateration principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed stations are installed at arbitrary positions in a building, then the system configuration is simple, but the position estimation accuracy deteriorates due to multipathing effects
Solution Approach 1:
The patent applies local quality by specifying particular installation positions for fixed stations (ceiling, wall, equipment) rather than arbitrary positions. Each location provides specific geometric relationships that minimize multipathing effects. The insulating spacers create localized isolation zones around fixed stations, ensuring optimal signal reception characteristics at these specific locations while maintaining overall system simplicity.
2Measurement precision
If fixed stations are installed close to the mobile object (within predetermined distance), then the signal strength measurement accuracy is improved, but the coverage area of each fixed station is reduced
Solution Approach 1:
The patent resolves this contradiction by utilizing vertical dimension for fixed station installation (ceiling, wall, equipment surfaces) rather than only horizontal placement. This dimensional approach allows fixed stations to be positioned close to mobile objects in the vertical direction while maintaining adequate horizontal coverage. The insulating spacers extend the effective coverage area by isolating the fixed station's electromagnetic field, allowing proximity installation without excessive signal confinement.
3Measurement precision
If radio waves are transmitted with high power, then the signal strength is sufficient for accurate measurement, but the power consumption increases and adjacent area interference occurs
Solution Approach 1:
The patent applies local quality by creating localized signal zones using insulating spacers around each fixed station. These spacers confine the electromagnetic field to specific local areas, allowing low-power transmission while maintaining sufficient signal strength at the intended reception points. This localized field confinement eliminates the need for high-power transmission, reducing both power consumption and interference with adjacent areas.
4Measurement precision
If the fixed station is installed without isolation from surrounding structures, then the installation is easier, but the receiving characteristics become directional and measurement accuracy deteriorates
Solution Approach 1:
The patent introduces insulating spacers as intermediary elements between the fixed station and surrounding structures (ceiling, wall, equipment). These spacers act as mediators that electrically isolate the fixed station, preventing direct contact that would create directional receiving characteristics. The spacers are simple components that add minimal structural complexity while effectively achieving non-directional receiving characteristics through electromagnetic isolation.
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 configuration enables highly accurate position estimation of mobile objects by minimizing multipathing effects, stabilizing signal strength, and reducing computational load, while also simplifying system configuration and extending battery life through non-directional receiving characteristics and efficient power usage.
Implementation Method 1
the fixed station receives a radio signal from a mobile object and measures the signal strength of the received signal
Implementation Method 2
an influence of multipathing and the like
Data Source
AI summary
A position estimation system (11) includes: a plurality of fixed stations (100a-100d) installed inside a building, the plurality of fixed stations (100a-100d) each measuring the signal strength of a radio signal transmitted from a mobile object (300); and a calculator configured to estimate a position of the mobile object (300) based on the signal strengths measured at the plurality of fixed stations (100a-100d), wherein each of the plurality of fixed stations (100a-100d) is installed in such a position that a distance to a top part of the mobile object (300) is equal to or less than a predetermined distance when the mobile object (300) is directly below the fixed station (100a-100d).