Racket Inertial Sensor Six-DOF Motion Tracking

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Solution Overview

Problem

Current motion tracking and analysis techniques for racket sports, such as tennis, lack comprehensive real-time stroke reconstruction and analysis capabilities, particularly in integrating aerodynamic and kinematic data to provide detailed feedback for player performance improvement.

Innovation Solution

A racket system equipped with an inertial sensor array providing six degrees of freedom, connected to a processor that generates stroke profiles based on accelerometer and gyro data, allowing for real-time tracking and analysis, and includes a memory device for storing these profiles, along with optional external processing for offline analysis and aerodynamic studies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If an inertial sensor array with six degrees of freedom is integrated into the racket, then measurement precision and data comprehensiveness are improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvestroke reconstruction accuracyVSAvoidsensor integration complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple inertial sensors (accelerometers and gyroscopes) into an integrated sensor array that measures six degrees of freedom simultaneously. This merging of multiple measurement functions into a single integrated system improves measurement precision while managing device complexity through unified sensor architecture.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The inertial sensor array serves multiple functions: measuring linear acceleration, angular velocity, and reconstructing three-dimensional stroke trajectories. This multi-functionality allows a single sensor system to provide comprehensive stroke analysis data, improving measurement precision without proportionally increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Productivity

If real-time stroke profile generation and processing is implemented, then productivity and feedback timeliness are improved, but use of energy and computational requirements increase

Engineering Contradiction:
Improvestroke analysis speedVSAvoidprocessor energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary processing of sensor data by generating stroke profiles directly from raw accelerometer and gyro measurements in real-time. This preliminary action of data processing at the source enables immediate stroke analysis without requiring extensive post-processing, improving productivity while managing energy consumption through efficient on-device computation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex mechanical motion capture systems with inertial sensor-based electronic measurement and processing. This substitution uses digital signal processing and computational algorithms to generate stroke profiles, improving productivity and feedback timeliness while reducing the physical complexity of the measurement system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If comprehensive aerodynamic and kinematic data collection is performed, then measurement precision and analysis depth are improved, but device complexity and data processing requirements worsen

Engineering Contradiction:
Improveaerodynamic data accuracyVSAvoiddata processing system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the comprehensive stroke analysis into distinct components: kinematic data from inertial sensors and aerodynamic data from additional sensors. This segmentation allows for specialized processing of each data type, improving measurement precision for both kinematic and aerodynamic parameters while managing overall system complexity through modular data handling.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses an intermediary processing layer that combines kinematic and aerodynamic data to generate comprehensive stroke profiles. This intermediary layer integrates multiple data sources and applies computational models to produce unified stroke analysis, improving measurement precision while managing data processing complexity through structured integration.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables high-fidelity stroke reconstruction and analysis, providing detailed insights into player and racket performance, including aerodynamic forces, allowing for improved training and competitive abilities by offering real-time feedback and comprehensive data analysis.

Implementation Method 1

The basic inertial magnetic motion capture (IMMCAP) module consists of a 3D printed circuit board having MEMS sensors configured to provide a tri-axial accelerometer

Methodology Applied
Scientific EffectAccelerometer: Accelerometer

Implementation Method 2

a tri-axial gyroscope, and a tri-axial magnetometer all in communication with analog to digital converters to convert the analog motion data to digital data

Methodology Applied
Scientific EffectGyroscope: Gyroscope

Implementation Method 3

a tri-axial magnetometer all in communication with analog to digital converters to convert the analog motion data to digital data for determining classic inertial measurement and change in spatial orientation

Methodology Applied
Scientific EffectMagnetometer: Magnetometer

Implementation Method 4

tracking and analysis techniques for tennis and other racket sports. In particular, the invention concerns inertial sensor-based techniques for stroke reconstruction and analysis

Methodology Applied
Scientific EffectAerodynamic forces: Drag

Data Source

PatentEP3385937B1Racket sport inertial sensor motion tracking
Publication Date: 2020.08.19 ICUEMOTION LLC
  • EP3385937B1 patent drawingFigure 1A~1B
  • EP3385937B1 patent drawingFigure 2
  • EP3385937B1 patent drawingFigure 3A~3B

AI summary

A system for a racket comprises an inertial sensor for coupling to the racket, a processor connected to the inertial sensor, and a memory device connected to the processor. The inertial sensor includes an accelerometer array with three degrees of freedom in acceleration and a gyro array with three degrees of freedom in rotation. The processor is configured to generate stroke profiles describing acceleration and rotation of the racket based on signals from the accelerometer and the gyro arrays, and the memory device is configured to store the stroke profiles.