Headset Orientation via Pocket Phone Sensor Comparison
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Solution Overview
Problem
Head-mountable displays (HMDs) face challenges in determining the orientation of a wearer's head relative to their body without requiring a tracking device to be mounted at a specific location, which is necessary for providing accurate augmented-reality graphics that move with the wearer's body movements.
Innovation Solution
The method involves using sensor data from both the HMD and a tracking device, such as a mobile phone, to determine the forward-backward body axis and the orientation of the tracking device relative to this axis, allowing the HMD to calculate its own orientation relative to the body by comparing magnetometer and gyroscope readings, enabling the detection of three-dimensional head position changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a tracking device is mounted at a specific location on the body, then the accuracy of augmented-reality graphics is improved, but the ease of operation is worsened due to the need for precise mounting
Solution Approach 1:
The patent uses sensor data from the HMD itself as an intermediary to determine head orientation relative to the body, eliminating the need for a separately mounted tracking device. The HMD's sensors (accelerometer, gyroscope, magnetometer) serve as the intermediary measurement mechanism that directly provides the orientation information needed for accurate AR graphics without requiring additional mounting infrastructure.
Solution Approach 2:
The HMD performs self-measurement of head orientation using its own integrated sensors. The system uses its accelerometer to detect body movement, gyroscope to determine head orientation relative to the body, and magnetometer to establish magnetic north, thereby serving its own measurement needs without external assistance from separately mounted tracking devices.
2Measurement precision
If sensor data from multiple sources is processed, then the accuracy of head orientation determination is improved, but the device complexity is worsened
Solution Approach 1:
The patent combines data from multiple sensors (accelerometer, gyroscope, magnetometer) into a unified orientation determination system. The accelerometer measures body movement, the gyroscope measures head orientation relative to the body, and the magnetometer provides magnetic north reference, merging these complementary measurements to achieve accurate three-dimensional head orientation without requiring separate tracking devices.
Solution Approach 2:
The HMD's sensor system serves multiple functions: the accelerometer detects both body movement and head orientation changes, the gyroscope measures rotational orientation, and the magnetometer establishes magnetic reference. This multi-functional sensor integration allows a single device to perform what would traditionally require multiple separate tracking devices, reducing overall system complexity while maintaining measurement 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
This approach allows HMDs to accurately determine head orientation relative to the body without the need for a fixed tracking device mounting, enhancing the rendering of augmented-reality graphics that move with the wearer's body, such as applications appearing over the shoulders.
Implementation Method 1
determining a heading of the HMD relative to magnetic north based on magnetometer data from the HMD
Implementation Method 2
determining an orientation of the HMD relative to the tracking device based on gyroscope data from the HMD and the tracking device
Data Source
AI summary
Methods and systems are described that involve a wearable computing device or an associated device determining the orientation of a person's head relative to their body. To do so, example methods and systems may compare sensor data from the wearable computing device to corresponding sensor data from a tracking device that is expected to move in a manner that follows the wearer's body, such a mobile phone that is located in the wearable computing device's wearer's pocket.