Wearable Capacitive Sensing for Drift Calibration and Motion Detection
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Solution Overview
Problem
Wearable devices face challenges in integrating intelligent capabilities due to limited space, making it difficult to incorporate effective sensors that can accurately detect component drift and user interaction.
Innovation Solution
Incorporating capacitive sensors into wearable devices that use capacitance sensing and calibration logic to determine when a conductive surface is in proximity, allowing for deferred drift calibration and enabling motion detection, thereby optimizing sensor performance and user interaction detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If capacitive sensors are integrated into wearable devices, then user interaction detection capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the capacitive sensor, drift calibration logic, and motion detection logic into a single integrated sensor system. The capacitive sensor serves multiple functions: detecting user interaction (touch/swipe gestures), performing drift calibration to maintain accuracy, and detecting motion through capacitance changes. This merging reduces the number of separate components needed in the wearable device.
Solution Approach 2:
The capacitive sensor is designed to perform multiple functions simultaneously: it detects user interactions through direct touch and swipe gestures, performs drift calibration by detecting when the device is stationary, and detects motion through changes in capacitance. This multi-functionality allows a single component to address multiple detection needs, reducing overall device complexity.
2Measurement precision
If drift calibration is performed continuously, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The drift calibration process is made dynamic rather than static. The system continuously monitors capacitance values and automatically determines when drift calibration is needed based on detected changes. When the device is stationary and no user interaction is detected, the system performs drift calibration. When motion or user interaction is detected, the system suspends calibration to conserve energy. This dynamic approach optimizes both precision and energy consumption.
Solution Approach 2:
The system uses feedback from continuous capacitance monitoring to control the drift calibration process. The capacitive sensor provides real-time feedback about device state (stationary vs. moving, touched vs. untouch ed), and this feedback controls when calibration operations are performed. The system only performs calibration when the feedback indicates appropriate conditions (device stationary, no user interaction), thereby optimizing energy usage while maintaining precision.
3Volume of moving object
If sensor size is reduced to fit wearable devices, then device portability is improved, but measurement precision deteriorates
Solution Approach 1:
The patent employs parameter changes in the calibration process to compensate for the small sensor size. By performing drift calibration and adjusting capacitance baseline values, the system compensates for environmental factors and manufacturing variations that have greater impact on smaller sensors. The calibration process modifies operational parameters to optimize the sensitivity and accuracy of the miniaturized capacitive sensor, maintaining measurement precision despite reduced physical dimensions.
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
This solution enables efficient detection of user interaction and optimal sensor performance by deferring drift calibration until necessary, ensuring accurate capacitance readings and reliable operation in wearable devices with limited space.
Implementation Method 1
a capacitive sensor within the housing. The sensor may be coupled to capacitance sensing and calibration logic that is operative to perform the disclosed methods
Data Source
AI summary
A wearable device includes a capacitive sensor and capacitance sensing and calibration logic operative to determine that component drift for a capacitive sensor cannot be determined based on a capacitance sensed by the capacitive sensor. The capacitance sensing and calibration logic deactivates a drift calibration operation for the capacitive sensor while the capacitive sensor senses the capacitance. The capacitance sensing and calibration logic is further operative to determine that the capacitance sensed by the capacitive sensor is within a detection threshold that indicates that a conductive surface is within proximity of the capacitive sensor. The capacitance sensing and calibration logic can also determine that a wearable device, that includes the capacitive sensor, is in motion based on sensed intermittent changes in the capacitance. Various other methods of operation are disclosed.