Wearable Motion Tracking Calibration with Simulated Magnetometer Data
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Solution Overview
Problem
Wearable audio devices face challenges in accurately estimating position and orientation due to the absence of magnetometers, leading to inaccuracies in yaw direction measurements and calibration drift caused by hardware aging and temperature changes.
Innovation Solution
A wearable device equipped with an accelerometer, gyroscope, and processing unit performs motion tracking calibration using simulated magnetometer data from an offboard computing device, incorporating 9DOF tracking to correct for yaw drift and temperature effects, ensuring accurate spatial audio localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometer is used in wearable audio device, then position and orientation estimation accuracy is improved, but device complexity and electromagnetic interference increase
Solution Approach 1:
The patent uses an offboard computing device as an intermediary to generate simulated magnetometer data based on imaging sensor data. This simulated data is then transmitted to the wearable audio device to correct yaw drift without requiring a physical magnetometer in the wearable device, thus avoiding electromagnetic interference while maintaining measurement accuracy.
Solution Approach 2:
The patent creates a copy of magnetometer functionality through simulated magnetometer data generated from imaging sensor data captured by an offboard computing device. This virtual copy provides the necessary magnetic field information without requiring actual magnetic sensing hardware in the wearable device.
2Measurement precision
If magnetometer is used in wearable audio device, then yaw direction measurement accuracy is improved, but electromagnetic interference from speakers increases
Solution Approach 1:
The offboard computing device acts as an intermediary that captures imaging data and generates simulated magnetometer data, isolating the magnetic field measurement function from the electromagnetic environment of the wearable audio device's speakers.
Solution Approach 2:
The patent replaces the physical magnetometer (electromagnetic sensing system) with an optical-based imaging system that captures visual information and processes it into simulated magnetometer data, substituting electromagnetic measurement with optical measurement.
3Device complexity
If hardware components are used without calibration correction, then device simplicity is maintained, but calibration drift from hardware aging and temperature changes increases
Solution Approach 1:
The patent implements a feedback mechanism where simulated magnetometer data continuously corrects yaw drift in the wearable device's orientation estimates. This ongoing calibration process compensates for hardware aging and temperature effects, maintaining reliability without adding complex calibration hardware.
Solution Approach 2:
The system performs preliminary calibration by using imaging sensor data to establish accurate reference frames before motion tracking begins, and continuously updates these references to account for environmental changes and hardware drift.
Data Source
AI summary
A wearable device is provided, including an accelerometer, a gyroscope, and a processing device. The processing device is configured to receive acceleration data from the accelerometer, receive orientation data from the gyroscope, and receive simulated magnetometer data from an offboard computing device. Based at least in part on the acceleration data, the orientation data, and the simulated magnetometer data, the processing device is further configured to perform motion tracking calibration to obtain an estimated position and orientation of the wearable device relative to the offboard computing device. The processing device is further configured to output the estimated position and orientation to an additional computing process.