Inertial Sensor Cadence Detection via Frequency Analysis
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Solution Overview
Problem
Conventional personal health monitors are cumbersome and unable to accurately measure cadence in various scenarios, such as cycling and running, due to their size and limited functionality.
Innovation Solution
A cadence measurement system using an inertial sensor mounted on or near the user's body, which determines cadence by analyzing frequency components of inertial signals and applying peak frequency to threshold comparisons to differentiate between walking, running, and cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional cyclocomputers with sensors mounted to crank arm and frame are used to monitor cycling cadence, then cycling cadence can be measured, but the device becomes cumbersome and cannot easily be used with multiple bicycles
Solution Approach 1:
The patent replaces the mechanical sensor system mounted on the bicycle (crank arm and frame sensors) with an inertial measurement unit (IMU) that uses accelerometers and gyroscopes to detect body motion. This substitution eliminates the need for mechanical mounting on the bicycle, making the device portable and versatile for use with multiple bicycles or other activities like running and walking.
Solution Approach 2:
The inertial sensor system is designed to be universal and can measure cadence for multiple activities including cycling, running, and walking. The same wearable device can be used across different scenarios, eliminating the need for activity-specific devices and enabling use with multiple bicycles or other transportation modes.
2Measurement precision
If conventional devices are used to monitor cycling cadence, then cycling-specific measurement is possible, but accurate estimation of steps per minute for running cannot be provided
Solution Approach 1:
The inertial sensor system is designed to be universal and can measure cadence for multiple activities including cycling, running, and walking. The same wearable device can be used across different scenarios, eliminating the need for activity-specific devices and enabling use with multiple bicycles or other transportation modes.
Solution Approach 2:
The system adapts to different activities by detecting and analyzing different motion patterns and frequency characteristics. The processing system identifies whether the user is cycling, running, or walking by analyzing the inertial data patterns, and adjusts the measurement interpretation accordingly to provide accurate cadence for each specific activity.
3Adaptability or versatility
If inertial sensors are used to determine cadence from frequency components, then accurate cadence measurement for multiple activities is achieved, but the system complexity increases
Solution Approach 1:
The signal processing is segmented into distinct stages: raw inertial data collection, frequency domain transformation (FFT), peak frequency identification, harmonic analysis, and cadence calculation. This segmentation allows each stage to be optimized independently and simplifies the overall processing architecture by breaking down the complex task into manageable steps.
Solution Approach 2:
The patent uses frequency domain analysis as an intermediary between the raw inertial sensor data and the final cadence measurement. By transforming the time-domain signal into the frequency domain, the system can easily identify peak frequencies and harmonics, which simplifies the cadence calculation process compared to direct time-domain analysis.
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 cadence measurements for a wide range of activities, including cycling and running, by effectively distinguishing between peak frequencies and their harmonics, allowing for precise tracking of user performance.
Implementation Method 1
an inertial sensor configured to output an inertial signal comprising one or more frequency components
Data Source
AI summary
The method and apparatus disclosed herein determine a user cadence from the output of an inertial sensor mounted to or proximate the user's body. In general, the disclosed cadence measurement system determines the user cadence based on frequency measurements acquired from an inertial signal output by the inertial sensor. More particularly, a cadence measurement system determines a user cadence from an inertial signal generated by an inertial sensor, where the inertial signal comprises one or more frequency components. The cadence measurement system determines a peak frequency of the inertial signal, where the peak frequency corresponds to the frequency component of the inertial signal having the largest amplitude. After applying the peak frequency to one or more frequency threshold comparisons, the cadence measurement system determines the user cadence based on the peak frequency and the frequency threshold comparison(s).