MEMS Sensor Motion Offset for Pedestrian Direction Accuracy
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Solution Overview
Problem
MEMS-based dead reckoning in mobile devices is prone to inaccuracies due to uncertainties in the direction of movement, often resulting in incorrect direction of travel estimates, especially when the device undergoes swinging or other movements that confuse algorithms.
Innovation Solution
The technique involves identifying the type of motion the mobile device is subject to and offsetting vertical acceleration data with horizontal acceleration data by a predetermined time offset, using the offset data to determine a corrected direction of travel, which is then used to enhance the accuracy of dead reckoning estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS sensor data is used for dead reckoning, then location determination capability is provided, but direction of travel accuracy deteriorates due to device swinging and movements
Solution Approach 1:
The patent segments the acceleration data into vertical and horizontal components, processing them separately with different time offsets. This segmentation allows the system to handle the distinct characteristics of vertical bouncing motion versus horizontal swinging motion, improving direction determination accuracy while maintaining location determination capability
Solution Approach 2:
The patent applies preliminary time offset adjustments to the vertical acceleration data based on the identified motion type before combining it with horizontal data. This preliminary action compensates for the phase difference between vertical and horizontal accelerations during walking, preventing direction determination errors before they occur
2Ease of operation
If vertical acceleration data is combined with horizontal acceleration data, then direction of travel can be determined, but errors increase due to phase differences from bouncing and swinging motions
Solution Approach 1:
The system performs preliminary identification of the motion type (bouncing, swinging, or combined) and applies appropriate time offsets to vertical acceleration data before combining it with horizontal data. This preliminary adjustment aligns the phases of vertical and horizontal acceleration components, enabling accurate direction determination without errors from motion-induced phase differences
Solution Approach 2:
The patent changes the time parameter (applying different time offsets) to the vertical acceleration data based on the identified motion type. By adjusting this parameter, the system compensates for phase differences caused by bouncing and swinging motions, allowing accurate combination of vertical and horizontal acceleration data for direction determination
Data Source
AI summary
Techniques provided herein are directed toward resolving a direction of travel of a mobile device based on MEMS sensor data by identifying a type of motion the mobile device is subject to and offsetting vertical acceleration data with horizontal acceleration data by a predetermined time offset based on the identified type of motion. The offset vertical and horizontal acceleration data can then be used to resolve, with an increased accuracy, a direction of travel of the mobile device.