Dual-Terminal Swimming Trajectory Correction Using Sensor Fusion
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Solution Overview
Problem
Existing GPS-based sports tracking devices struggle to accurately record swimming trajectories due to satellite signal obstruction underwater, leading to cumulative errors and instability issues with arm-mounted sensors, limiting their applicability to strokes where the arm frequently breaks the water surface.
Innovation Solution
A dual-terminal system where one terminal collects swimming direction and acceleration, and another terminal collects positioning data, allowing for trajectory determination without real-time positioning data and subsequent correction using satellite positioning when available, reducing errors across various swimming strokes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sports tracking apparatus with GPS positioning is fixed on the user's arm during swimming, then the device can record positioning data when the arm is out of water, but the satellite signal cannot be transmitted through water leading to incomplete trajectory data
Solution Approach 1:
The patent introduces an intermediary calculation method that uses swimming direction and acceleration data as intermediate parameters to infer position changes underwater, bridging the gap between surface positioning and underwater movement without requiring direct satellite signal transmission through water
Solution Approach 2:
The system performs preliminary trajectory calculation using sensor data (swimming direction and acceleration) before positioning data becomes available, and then corrects the trajectory when positioning data is obtained, ensuring continuous trajectory recording despite intermittent positioning signal loss
2Measurement precision
If a movement sensor is fixed on the arm to recognize swimming trajectory, then continuous trajectory data can be obtained, but the speed cumulative error increases with time and is affected by arm swing instability
Solution Approach 1:
The patent implements a feedback correction mechanism where positioning data obtained when the arm is out of water is used to correct and adjust the cumulative trajectory calculation, creating a closed-loop system that reduces error accumulation over time
Solution Approach 2:
The trajectory determination is segmented into two parts: continuous estimation using movement sensors during swimming, and correction using positioning data when available. This segmentation allows the system to maintain accuracy by periodically resetting the cumulative error through positioning corrections
3Measurement precision
If positioning data is obtained continuously, then trajectory accuracy can be maintained, but the device cannot accurately record trajectories for strokes where the arm does not frequently break the water surface
Solution Approach 1:
The patent creates a universal trajectory determination method that works for all swimming strokes by combining two data sources: movement sensors that continuously capture swimming dynamics and positioning data that periodically provides location corrections, making the system adaptable to any stroke type regardless of arm exposure frequency
Data Source
AI summary
An outdoor swimming trajectory determination method includes in a situation where positioning data is not obtained, obtaining a swimming direction of a user and a swimming acceleration of the user, the swimming direction being collected by a first terminal, determining a swimming trajectory of the user according to the swimming direction and the swimming acceleration, and in a situation where the positioning data is obtained, correcting the swimming trajectory according to the positioning data, The swimming acceleration is collected by at least one of the first terminal or a second terminal. The positioning data is collected by the second terminal.