Multi-Modal Kalman Filter for Mobile Device Location Consistency

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Solution Overview

Problem

Existing location determination methods in mobile devices often yield inconsistent and erratic location estimates due to the use of single Kalman filters on multi-modal location data from different sources, such as GPS and wireless access points, leading to inaccurate positioning.

Innovation Solution

Implementing a multi-modal Kalman filter that maintains multiple location approximations, each determined by filtering a subset of location estimates using a respective Kalman filter, and designates one as active based on consistency with recent data, allowing for smoother and more consistent location estimation by switching between approximations as data quality changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single Kalman filter is used to process location estimates from multiple sources, then the device complexity is reduced, but the location estimation becomes inconsistent and erratic

Engineering Contradiction:
Improvefiltering system complexityVSAvoidlocation estimation consistency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent divides the location estimation problem into multiple independent Kalman filters, each handling a specific subset of location data sources (e.g., GPS-only, Wi-Fi-only, cellular-only). This segmentation allows each filter to process homogeneous data with consistent characteristics, avoiding the inconsistency that arises when a single filter processes heterogeneous multi-modal data together.

Inventive Principle:
Principle #1Segmentation

2Reliability

If multiple independent Kalman filters are used to process different subsets of location data, then the location estimation consistency is improved, but the device complexity increases

Engineering Contradiction:
Improvelocation estimation consistencyVSAvoidfiltering system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a dynamic selection mechanism that chooses which Kalman filter approximation to use based on current data quality and availability. The system dynamically adjusts the active filter based on real-time conditions such as GPS signal strength, Wi-Fi availability, and cellular network status, allowing the system to maintain consistency while adapting to changing environments without requiring all filters to operate simultaneously at full complexity.

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If location estimates from different sources are averaged, then the computation is simple, but the location accuracy deteriorates when estimates differ significantly

Engineering Contradiction:
Improvecomputation simplicityVSAvoidlocation accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

Instead of averaging all location estimates together, the patent segments the estimates by source type and processes them through separate Kalman filters. This allows the system to maintain computational simplicity within each homogeneous group while avoiding the accuracy degradation that occurs when significantly different estimates from heterogeneous sources are averaged together.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS8768618B1Determining a location of a mobile device using a multi-modal kalman filter
Publication Date: 2014.07.01 GOOGLE LLC
  • US8768618B1 patent drawing
  • US8768618B1 patent drawing
  • US8768618B1 patent drawing

AI summary

Methods and systems for determining a location of a mobile device using a multi-modal Kalman filter are described. According to an example method, a mobile device may maintain multiple approximations of a location of a mobile device. Each approximation includes an estimated geographic location of the mobile device that is determined by filtering a respective subset of location estimates received by the mobile device using a respective Kalman filter, and one of the multiple approximations is designated as an active approximation. The method also involves receiving data indicating an estimate of a geographic location of the mobile device and, based on a distance between the estimate of the geographic location and a given approximation of the multiple approximations, updating the given approximation using the estimate of the geographic location. Additionally, the method involves providing for display a visual indication of an estimated geographic location associated with the active approximation.