PPG Heart Rate Sampling During Motion With Activity-Based Timing
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Solution Overview
Problem
Existing PPG sensors struggle to accurately measure physiological signals during predetermined activities like walking, climbing stairs, or biking without requiring user input, as they are affected by motion artifacts and noise, leading to inaccurate heart rate measurements.
Innovation Solution
The system employs criteria such as inter-sampling waiting time, continuous motion criteria, predetermined activity criteria, and confidence values to minimize the effects of motion during these activities, using light sources and detectors to measure physiological parameters like heart rate, and switches between modes to optimize accuracy and battery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PPG sensors continuously measure physiological signals during predetermined activities, then measurement completeness is improved, but measurement precision deteriorates due to motion artifacts and noise
Solution Approach 1:
The system dynamically adjusts the sampling strategy based on detected activity state. During predetermined activities like walking or running, the system switches from continuous sampling to periodic sampling triggered by motion detection events, allowing measurements during activity while adapting to motion conditions
Solution Approach 2:
The system changes measurement parameters based on activity detection. When motion is detected, the system adjusts sampling intervals, integration times, and signal processing filters to optimize measurements under motion conditions, balancing completeness with precision
2Measurement precision
If PPG sensors take frequent physiological measurements during activities, then data quality is improved, but power consumption increases
Solution Approach 1:
Instead of continuous measurement, the system uses periodic sampling triggered by motion detection events. The accelerometer detects activity patterns and triggers PPG measurements at appropriate intervals, reducing overall measurement frequency while capturing physiologically relevant data during activities
Solution Approach 2:
The system uses the accelerometer's motion detection capability to automatically trigger and control PPG measurements without continuous processor intervention. The motion sensor serves the dual purpose of activity detection and measurement triggering, optimizing power usage
3Reliability
If the system requires user input to initiate measurements, then measurement reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The system automatically detects predetermined activities using the accelerometer and autonomously initiates PPG measurements without requiring user input. The motion sensor detects activity patterns and triggers the measurement sequence automatically, making the system self-activating while maintaining reliability through activity-based triggering
4Measurement precision
If the system uses multiple sampling criteria and modes, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measurement system is segmented into distinct operational modes (continuous mode, periodic mode, event-triggered mode) with dedicated control logic for each. This modular approach allows precise control in each mode while keeping individual mode complexities manageable through clear separation of functions
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 effectively measures physiological signals during predetermined activities by ensuring accurate heart rate detection, reducing power consumption, and maintaining measurement quality by adjusting sampling intervals and sensor configurations based on activity type.
Implementation Method 1
The amount of light measured by the light detectors can vary based on the amount of light absorbed by the user's tissue
Implementation Method 2
The one or more light detectors can receive and measure light that has been transmitted through, reflected by, and/or scattered within and exited the user's tissue
Implementation Method 3
The one or more light detectors can receive and measure light that has been transmitted through, reflected by, and/or scattered within and exited the user's tissue
Implementation Method 4
The light detector(s) can convert the measured light into an electrical signal indicative of the intensity thereof
Data Source
AI summary
This disclosure relates to methods for measuring one or more physiological signals while the user is engaged in a predetermined activity. Exemplary predetermined activities can include activities such as walking, climbing stairs, biking, and the like. The physiological measurements can include, but are not limited to, heart rate signals. The physiological measurements may be affected by the predetermined activity, so the system may be configured to employ one or more criteria prior to measuring physiological information to minimize the effects. The one or more criteria can include, but are not limited to, an inter-sampling waiting time, continuous motion criteria, predetermined activity criteria, a post-physiological measurement amount of time, and a confidence value. The continuous motion criteria can be based on the type of predetermined activity. For example, walking may have walking state criteria and a step count criteria.