Wearable Activity Monitor Heart Rate Offset Algorithm
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Solution Overview
Problem
Existing wearable activity monitoring devices, particularly those using wrist-based acceleration sensors, provide inaccurate and inconsistent activity estimates due to wrist movement variability, and suffer from short battery life when continuously measuring heart rate data.
Innovation Solution
A wearable device with both acceleration and heart rate sensors that operates in alternating modes to compute and update heart rate offset and activity gain values, reducing battery consumption by intermittent data reading and using linear extrapolation for extended battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous heart rate measurement is performed using optical sensors, then accurate physiological data is obtained, but battery life is significantly reduced
Solution Approach 1:
The patent implements periodic sampling of heart rate data at predetermined intervals rather than continuous measurement. The processing unit reads heart rate data from the optical sensor only at scheduled intervals, allowing the device to alternate between measurement mode and low-power mode, thereby extending battery life while still capturing sufficient physiological data for accurate activity monitoring.
Solution Approach 2:
The device dynamically adjusts its operating mode based on activity detection. When acceleration sensors detect movement exceeding predetermined thresholds, the device transitions to a measurement mode where heart rate data is collected. During periods of low or no activity, the device enters a low-power mode with extended intervals between measurements, optimizing the balance between measurement accuracy and power consumption.
2Device complexity
If acceleration-based activity monitoring is used, then device complexity is reduced, but measurement accuracy deteriorates due to wrist movement variability
Solution Approach 1:
The patent combines data from multiple sensors including acceleration sensors and optical heart rate sensors to monitor physical activity. By merging information from these different sensor types, the processing unit can distinguish between various activity types (such as walking versus running) more accurately than using acceleration data alone, while still maintaining relatively simple device architecture.
Solution Approach 2:
The processing unit acts as an intermediary that correlates acceleration data with heart rate data to improve activity classification accuracy. By using heart rate information as an additional parameter to interpret acceleration patterns, the system can more reliably determine the type and intensity of activity being performed, compensating for the limitations of wrist-based acceleration sensing.
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 device provides more accurate activity monitoring by distinguishing between walking and running activities and extends battery life by intermittent data processing, allowing continuous, reliable heart rate monitoring without frequent battery replacement.
Implementation Method 1
at least one first sensor for measuring acceleration data relating to movements of said person
Implementation Method 2
at least one second sensor for measuring heart rate data corresponding to the heart beat rate of said person
Data Source
AI summary
The invention relates to wearable electronic devices for monitoring physical activities of a person. The invention also concerns related methods and computer program products. According to the invention, a first sensor for measuring acceleration data and a second sensor for measuring heart rate data is provided. A data processing unit is configured to operate in a first mode when data is read from said first and second sensors and in a second mode when data is not read from at least one of said first and second sensors. In the first operating mode the processing unit cumulatively computes and updates a heart rate offset value based on at least one of the following data: a predetermined pulse of the person a rest, a predetermined fitness level of the person, a current recovery pulse of the person, and/or the cumulated acceleration data during the current activity. It also computes a current activity gain value based on acceleration data and heart beat rate data. The data processing unit is further configured to compute an estimate of the heart beat rate based on said offset value and said gain value during said second operating mode.