Swing Analysis Using Sweet Spot Trajectory Reference Frame
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Solution Overview
Problem
Current methods for analyzing baseball swings using motion capture sensors face challenges in interpreting sensor data due to the rotational symmetry of the bat, which complicates the transformation of data into a meaningful reference frame, and lack methods to combine sweet spot trajectory analysis with swing plane reference frames.
Innovation Solution
The method transforms sensor data from a local reference frame to a swing plane reference frame, defined by the bat's orientation and impact velocity, allowing for detailed characterization of the swing and calculation of metrics such as swing plane speed, tempo, and sweet spot trajectory, using sensors like accelerometers and gyroscopes to capture bat motion and impact data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sensor data is captured in a local reference frame defined by sensor geometry, then the data can be easily collected during the swing, but the data becomes difficult to interpret due to constant movement and rotation of the reference frame
Solution Approach 1:
The patent introduces an intermediary coordinate transformation process that converts sensor data from the moving local reference frame to a fixed global reference frame. This intermediary transformation enables the data to maintain ease of collection while becoming interpretable by eliminating the effects of bat rotation and movement.
Solution Approach 2:
The patent changes the reference frame parameters from a moving local coordinate system to a fixed global coordinate system. This parameter change allows the same sensor data to be collected easily during swing motion while becoming meaningful for analysis by removing the time-varying rotational components.
2Reliability
If vector magnitudes are used to define swing metrics, then the metrics are invariant to rotations in the sensor reference frame, but detailed and physically meaningful information is lost
Solution Approach 1:
The patent segments the swing analysis into two parts: using vector magnitudes for rotation-invariant metrics and using transformed vector components for detailed information. This segmentation allows both reliability through invariance and information retention by analyzing different aspects of the data separately.
Solution Approach 2:
The patent adds another dimension to the analysis by transforming sensor data into a global reference frame, enabling extraction of both rotation-invariant magnitudes and directionally-specific components. This dimensional transformation preserves information that would otherwise be lost to rotation.
3Measurement precision
If a swing analysis method combines sweet spot trajectory with swing plane reference frame, then detailed characterization of swing performance is achieved, but the complexity of the analysis method increases
Solution Approach 1:
The patent creates a universal analysis framework that works for any swing type and equipment by defining a general swing plane reference frame. This multi-functional approach enables detailed characterization across different scenarios without requiring separate complex methods for each case.
Solution Approach 2:
The patent introduces dynamic elements to the reference frame by defining the swing plane based on the actual motion trajectory of the sweet spot. This dynamic reference frame adapts to each swing's unique characteristics, providing precise characterization while maintaining a systematic analysis approach.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a detailed analysis of the swing, enabling comparison across swings, performance rating, and feedback to users, improving swing efficiency and power by accurately capturing and interpreting the bat's motion and impact dynamics.
Implementation Method 1
accelerometer data, i.e., or acceleration data, may detect the shock of the impact
Implementation Method 2
a three axis gyroscope... The angular velocity vector of the bat, which is the rotational axis that is perpendicular to the bat's instantaneous plane of rotation
Data Source
AI summary
A method for analyzing sensor data from baseball swings (or swings in similar sports) that transforms data into a reference frame defined by the bat orientation and velocity at impact. The trajectory of the sweet spot of the bat is tracked through the swing, and is analyzed to generate metrics describing the swing. A two-lever model of the swing may be used to model the effects of body rotation and wrist rotation. Data may be analyzed to identify relevant events during the swing such as start of downswing, commit (wrist release), on-plane, peak bat speed, and impact. Illustrative swing metrics derived from the sweet spot trajectory, the swing plane reference frame, and the two-lever model include: forward bat speed, on-plane rotation, hinge angle at commit, hinge angle at impact, body rotation ratio, body tilt angle, and swing plane tilt angle.