Swing Analysis System Reference Frame Transformation
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Solution Overview
Problem
Current methods for analyzing swings in sports, such as golf or baseball, face challenges in interpreting motion sensor data due to rotational symmetry and lack of transformation to a meaningful reference frame, limiting the ability to correlate data with swing mechanics and efficiency.
Innovation Solution
A swing analysis system transforms sensor data from a local reference frame to a swing plane reference frame, enabling detailed characterization of swings by defining metrics like swing plane speed, tempo, and trajectory, and providing performance ratings and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor data is analyzed in the local sensor reference frame, then the measurement is straightforward and invariant to rotations, but the data lacks physical meaning and cannot be correlated with swing mechanics
Solution Approach 1:
The patent transforms the reference frame parameters from a fixed sensor-local coordinate system to a dynamic swing-plane coordinate system that rotates and translates with the swing. This parameter transformation enables the data to reflect actual swing mechanics while maintaining measurement accuracy through mathematical transformation matrices that preserve the underlying physical quantities.
Solution Approach 2:
The patent introduces an intermediary transformation process that mediates between the sensor's local reference frame and the meaningful swing plane reference frame. This intermediary mathematical transformation preserves the measurement invariance while recovering the physical meaning by mapping sensor readings to swing-relevant coordinates through rotation and translation operations.
2Device complexity
If a fixed reference frame is used for sensor data, then the coordinate system remains stable and simple, but it cannot capture the dynamic nature of swing motion and orientation changes
Solution Approach 1:
The patent transforms the static, fixed reference frame into a dynamic reference frame that moves and rotates with the swing. The swing plane reference frame is continuously updated based on the swing's instantaneous orientation and position, allowing the system to capture dynamic swing motions while maintaining computational tractability through efficient coordinate transformation algorithms.
3Reliability
If vector magnitudes are emphasized for swing metrics, then the metrics are invariant to sensor rotations, but individual components along transformed axes provide more detailed and physically meaningful information
Solution Approach 1:
The patent changes the parameter representation from scalar vector magnitudes to decomposed components along swing-relevant axes. By transforming the data into the swing plane reference frame, the system preserves the invariance property while recovering detailed information about swing mechanics through the individual x, y, z components that correspond to specific swing directions and planes.
Data Source
AI summary
A system that measures a swing of equipment (such as a bat or golf club) with inertial sensors, and analyzes sensor data to create a rotational profile. Swing analysis may use a two-lever model, with a body lever from the center of rotation to the hands, and an equipment lever from the hands to the sweet spot of the equipment. The rotational profile may include graphs of rates of change of the angle of the body lever and of the relative angle between the body lever and the equipment lever, and a graph of the centripetal acceleration of the equipment. These three graphs may provide insight into players' relative performance. The timing and sequencing of swing stages may be analyzed by partitioning the swing into four phases: load, accelerate, peak, and transfer. Swing metrics may be calculated from the centripetal acceleration curve and the equipment/body rotation rate curves.