Accelerometer Swim Stroke Segmentation With Envelope Signal Detection

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Solution Overview

Problem

Existing swim tracking solutions rely on IMU sensors like gyroscope or magnetometer for stroke segmentation, which have high power consumption.

Innovation Solution

A controller using an accelerometer to filter input signals, determine parameters, generate an envelope signal, and segment swim strokes, with an activity detection module to validate stroke segments and reduce false positives.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gyroscope or magnetometer is used for stroke segmentation, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improvestroke segmentation accuracyVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the sensor type parameter from high-power gyroscope/magnetometer to low-power accelerometer, and modifies the signal processing parameters (filtering, envelope detection, parameter extraction) to maintain segmentation accuracy while reducing energy consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical sensing system (gyroscope/magnetometer) with an accelerometer-based system combined with sophisticated signal processing algorithms to achieve the same stroke segmentation function with lower power consumption

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Use of energy by moving object

If accelerometer is used for stroke segmentation, then use of energy is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidstroke segmentation accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent introduces intermediate processing steps including filtering modules, envelope signal generation, and parameter extraction as mediators between the accelerometer and the stroke segmentation decision, enabling accurate stroke detection despite using a lower-cost sensor

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the signal processing into distinct stages (filtering, envelope detection, parameter extraction, stroke determination) to systematically extract stroke information from accelerometer data, improving measurement precision through multi-stage analysis

Inventive Principle:

Principle #1Segmentation

3Device complexity

If simple filtering is applied to accelerometer signal, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:

Improvesignal processing complexityVSAvoidstroke detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent employs dynamic adaptive filtering where the envelope signal and its derivatives are continuously updated based on incoming accelerometer data, allowing the system to adapt to varying swim strokes and conditions while maintaining manageable complexity

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12533552B2Controller and a method to determine a swim stroke

Publication Date: 2026.01.27 ROBERT BOSCH GMBH

AI summary

A controller is connected to receive an input signal from at least one accelerometer. The controller comprises an interface facilitating input and output pins/ports, and a filter module to filter the input signal from at least one accelerometer. The controller includes a stroke segmentation module configured to determine at least two parameters comprising a first parameter and a second parameter from the filtered input signal, generate an envelope signal using the at least two parameters and the filtered input signal, and determine the swim stroke of the swimmer based on the filtered input signal and the envelope signal. Further, an activity detection module is used in combination with the stroke segmentation module.