Wearable Audio Orientation Tracking via IMU and Distance Sensor Fusion
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Solution Overview
Problem
Detecting user orientation from wearable devices is challenging due to measurement errors caused by bias drift in inertial measurement units (IMUs), which complicates orientation-based control of these devices.
Innovation Solution
A wearable audio device equipped with an inertial measurement unit (IMU) and a set of distance sensors, such as infra-red, vision, ultrasonic, or 3D depth cameras, that verifies user orientation by correlating motion data from the IMU with positional data from the distance sensors to correct for drift and execute orientation-based actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If IMU is used to detect user orientation, then orientation tracking is enabled, but measurement precision deteriorates due to bias drift
Solution Approach 1:
The patent combines IMU with distance sensors (ToF, ultrasonic, or stereo cameras) to create a hybrid orientation detection system. The distance sensors provide periodic reference measurements that correct IMU drift, merging inertial data with absolute position references to maintain both continuous tracking and measurement precision.
Solution Approach 2:
The system implements feedback by using distance sensors to periodically verify and correct IMU-derived orientation. The controller compares IMU measurements with distance sensor readings and applies corrections to compensate for bias drift, creating a closed-loop system that maintains accuracy over time.
2Measurement precision
If distance sensors are added to verify orientation, then measurement precision improves, but device complexity increases
Solution Approach 1:
The distance sensors serve multiple functions: they verify orientation accuracy, provide drift correction references, and can independently measure distance to surfaces. This multi-functionality justifies the added complexity by extracting maximum utility from each additional sensor component.
Solution Approach 2:
The controller acts as an intermediary that fuses data from IMU and distance sensors, reconciling their different measurement approaches. It processes both data streams, identifies drift conditions, and applies corrections, mediating between the two sensor systems to produce accurate orientation output.
3Reliability
If orientation verification is implemented, then reliability improves by preventing false triggers, but loss of time increases due to additional verification steps
Solution Approach 1:
The system uses periodic verification where distance sensors check orientation at regular intervals rather than continuously. This periodic sampling provides sufficient drift correction to maintain reliability while minimizing the time overhead compared to continuous verification of both sensor systems.
Solution Approach 2:
The system performs preliminary orientation detection using the IMU, which provides rapid initial orientation estimates. Distance sensor verification is then applied selectively to correct drift, allowing the system to benefit from fast IMU response while periodically ensuring accuracy through verification.
Data Source
AI summary
Various implementations include devices, systems and approaches for tracking user orientation. In some cases, a wearable audio device includes: an electro-acoustic transducer for providing an audio output; an inertial measurement unit (IMU) for indicating motion of the wearable audio device; a set of distance sensors; and a controller coupled with the electro-acoustic transducer, the IMU and the set of distance sensors, the controller configured to: determine an orientation of a user of the wearable audio device based on the indication of motion from the IMU; verify the orientation of the user as detected by the IMU, using data from the set of distance sensors; and execute an orientation-based action in response to verifying the orientation of the user.