Wearable RF Sensing for Hand Tracking Beyond Camera View
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Solution Overview
Problem
Existing MR systems struggle to accurately track user movements, particularly when hands move outside the camera's field of view, and strain gauge sensors are cumbersome and not ideal for wearable applications.
Innovation Solution
A wearable device using RF sensors that oscillate at a preselected frequency to resonate with conductive matter on the user's body, generating a waveform that reflects movement, allowing for precise tracking without direct skin contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image analysis is used to track hand movement, then the system can detect hand position, but the tracking fails when the hand moves outside the camera's field of view
Solution Approach 1:
The patent replaces optical/image-based tracking with electromagnetic field-based RF sensing. The RF sensor detects changes in electromagnetic fields caused by conductive matter (such as salt water in sweat or electrolytes in blood) near the skin surface, enabling tracking without line-of-sight requirements and extending functionality beyond camera field of view.
Solution Approach 2:
The patent introduces conductive matter on or near the skin surface as an intermediary between the RF sensor and the tracking system. This intermediary modulates the electromagnetic field in response to hand movements, allowing the RF sensor to detect position changes through field perturbations rather than direct optical observation.
2Measurement precision
If strain gauge sensors are used to detect skin displacement, then movement can be monitored, but the sensors require close contact with skin and extend along the whole surface being sensed, making them cumbersome
Solution Approach 1:
The patent replaces mechanical strain gauge sensors with electromagnetic field-based RF sensing. This substitution eliminates the need for physical contact with the skin surface and removes the requirement for sensors to extend along the entire surface being sensed, thereby improving wearability and comfort while maintaining movement detection capability.
Solution Approach 2:
The patent extracts the sensing function from the bulk material (strain gauge extending along the surface) and concentrates it into a localized RF sensor that detects movements through electromagnetic field interactions with conductive matter, reducing the physical footprint and improving comfort.
3Ease of operation
If RF sensors are used to track conductive matter movement, then contact-free tracking is achieved, but the system requires the conductive matter to be within resonance distance of the sensor
Solution Approach 1:
The patent utilizes changes in electromagnetic field parameters (frequency, amplitude, phase) as conductive matter moves within the sensing range. The RF sensor is tuned to resonate at specific frequencies, and movements of conductive matter modulate these parameters, enabling detection while maintaining contact-free operation. The resonance condition creates a sensitive detection zone that balances range and precision.
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
Enables accurate, contact-free tracking of body movements, including health metrics, and interaction with holograms, even outside the camera's view, with a compact and comfortable design.
Implementation Method 1
The RF sensor is caused to oscillate at a preselected frequency. The RF sensor is tuned to resonate when the RF sensor is located a preselected distance from the user's conductive matter
Data Source
AI summary
A wearable device that tracks body movement is disclosed. The device includes a housing and a connection member. The connection member is coupled to the housing, and the connection member enables the device to be coupled to a user's body part. This body part is associated with the conductive matter. The device includes an RF sensor in the housing. The RF sensor oscillates at a preselected frequency. The RF sensor is tuned to resonate when the RF sensor is located a preselected distance from the conductive matter. As the conductive matter moves closer or farther from the RF sensor based on user movement, a resulting waveform generated based on data from the RF sensor is modified, and the resulting waveform is usable to determine how the user moved.