Indoor Localization via UWB and Motion Sensor Fusion
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Solution Overview
Problem
Existing indoor positioning techniques, such as Bluetooth and WiFi, suffer from poor accuracy, while UWB-based methods like TWR and ToA are not scalable for multiple users and pose privacy concerns, and DL-TDoA lacks robustness against multipath and occlusion.
Innovation Solution
The integration of motion sensor fusion with UWB DL-TDoA measurements to provide a robust and accurate indoor localization system, using a combination of UWB distance difference measurements and motion sensor data to calculate the location of an object, even in scenarios with poor or absent UWB signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If UWB-based localization techniques (TWR or ToA) are used, then measurement precision is improved, but device complexity and scalability worsen due to inability to cater to multiple users simultaneously
Solution Approach 1:
The patent segments the localization function into two independent parts: (1) UWB anchors transmit downlink signals and DL-TDoA calculations are performed by a central server, and (2) motion sensors independently track steps and headings. This segmentation allows multiple users to be served simultaneously without increasing anchor complexity, resolving the scalability issue while maintaining accuracy.
Solution Approach 2:
The patent introduces a central server as an intermediary that performs DL-TDoA calculations based on anchor measurements, freeing the anchors from complex bidirectional communication requirements. This intermediary enables multiple users to be localized simultaneously, improving scalability while maintaining measurement precision.
2Reliability
If motion sensor fusion is integrated with UWB DL-TDoA, then reliability is improved against multipath and occlusion, but device complexity increases
Solution Approach 1:
The patent merges UWB DL-TDoA measurements with motion sensor data (accelerometer, gyroscope, magnetometer) to create a hybrid localization system. Motion sensors provide continuous tracking independent of UWB signal quality, while UWB provides absolute position references. This combination improves reliability against multipath and occlusion by providing redundant measurement paths.
Solution Approach 2:
The patent dynamically switches between UWB-based localization and motion sensor-based dead reckoning based on signal availability. When UWB signals are strong, DL-TDoA provides accurate position fixes; when signals are weak or occluded, the system transitions to motion sensor fusion, maintaining continuous reliable localization throughout environmental variations.
Data Source
AI summary
A method includes receiving at least one wireless signal measurement and motion sensor measurements. The method also includes generating a location estimate based on the at least one wireless signal measurement. The method also includes determining whether a step is present based on the motion sensor measurements. The method also includes, in response to determining that a step is present, determining a step heading offset based on the location estimate and the motion sensor measurements, and determining a step length and heading based on the motion sensor measurements and the step heading offset. The method also includes determining a location of an object based on at least one of (i) the at least one wireless signal measurement or (ii) the step length and heading.