Shoe-Mounted Accelerometer Foot Strike Detection

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Solution Overview

Problem

Existing fitness tracking systems are complex, power-intensive, and expensive, with inadequate accuracy in determining foot strike patterns, which are essential for improving user experience and tracking metrics.

Innovation Solution

A fitness tracking system that includes a shoe-mounted monitoring device with an accelerometer to generate acceleration data, identifying foot strike patterns by sampling and analyzing acceleration data to determine local minima, thereby determining foot strike characteristic data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complicated pressure sensor arrangement is used to determine foot strike pattern, then measurement precision is improved, but device complexity increases and power consumption increases

Engineering Contradiction:

Improvefoot strike pattern detection accuracyVSAvoidsensor arrangement complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential information needed for foot strike pattern detection from the complex pressure sensor system. By using a single accelerometer to capture vertical acceleration data and identifying local minima in the acceleration signal, the system obtains sufficient information to determine foot strike patterns without the complexity of multiple pressure sensors.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical pressure sensor arrangement with an accelerometer-based system that measures acceleration forces. This substitution uses dynamic mechanical measurement (acceleration) instead of static pressure sensing, simplifying the device while maintaining the ability to detect foot strike patterns through signal processing of acceleration data.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If complicated pressure sensor arrangement is used to determine foot strike pattern, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefoot strike pattern detection accuracyVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent extracts only the essential measurement capability from complex sensor systems. By using a single accelerometer instead of multiple pressure sensors, the system maintains sufficient measurement precision for foot strike pattern detection while dramatically reducing component count and manufacturing complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs inexpensive accelerometer components that can be easily manufactured and integrated into footwear. The simplified sensor arrangement reduces bill of materials costs and assembly complexity, making the system more cost-effective for mass production compared to complex pressure sensor arrays.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Use of energy by moving object

If accelerometer is used to generate acceleration data, then power consumption is reduced, but measurement precision may be insufficient

Engineering Contradiction:

Improvepower consumptionVSAvoidfoot strike pattern detection accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent uses an accelerometer to measure vertical acceleration forces during foot strike, replacing more power-intensive pressure sensor systems. The accelerometer captures dynamic motion data that, when processed to identify local minima, provides sufficient precision for determining foot strike patterns while consuming less power.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses only the vertical acceleration component (partial action) from the accelerometer data to determine foot strike patterns. By focusing on the specific aspect of motion most relevant to foot strike detection and using signal processing to extract local minima, the system achieves adequate measurement precision without requiring full three-axis acceleration data or more complex sensing.

Inventive Principle:

Principle #16Partial or excessive action

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

The system provides accurate foot strike pattern analysis with reduced power consumption, improving user experience and tracking efficiency while being cost-effective and user-friendly.

Implementation Method 1

an accelerometer configured to generate acceleration data corresponding to acceleration of a foot

Methodology Applied

Scientific EffectAcceleration: Accelerometer

Data Source

PatentUS11564439B2System and method for determining foot strike pattern

Publication Date: 2023.01.31 UNDER ARMOUR INC

AI summary

A fitness tracking system includes a shoe, a monitoring device, and a controller. The monitoring device is mounted on the shoe and includes an accelerometer configured to generate acceleration data corresponding to acceleration of a foot received by the shoe. The controller is operably connected to the accelerometer and is configured to collect sampled acceleration data by sampling the generated acceleration data, to identify foot strike data of the sampled acceleration data, to identify a local minimum of the sampled acceleration data collected prior to the foot strike data, and to determine foot strike characteristic data corresponding to the foot strike data based on an acceleration value at the local minimum.