Adaptive Reference Head Tracking in Moving Environments
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Solution Overview
Problem
Head tracking in non-static environments, such as during movement, faces challenges in maintaining accurate placement of virtual objects relative to the user, as the frame of reference changes, leading to erroneous placement of virtual objects.
Innovation Solution
A system utilizing two or more inertial measurement units (IMUs) or sensors to track the user's head orientation and adjust the reference frame based on movement data, adapting the reference orientation to maintain accurate tracking of head movements, even in changing environments, through processing units that receive and process data from both head sensors and additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed reference frame is used for head tracking, then the system is simple to implement, but the placement of virtual objects becomes erroneous in non-static environments
Solution Approach 1:
The patent applies the dynamics principle by transforming the static reference frame into a dynamic one that adapts to user movement. The system continuously adjusts the reference frame orientation based on acceleration data from sensors, allowing it to respond to changes in the user's motion state. This enables accurate head tracking in non-static environments where the user is walking, running, or changing direction, as the reference frame moves with the user rather than remaining fixed in space.
2Reliability
If multiple sensors are used to detect frame of reference changes, then tracking accuracy in non-static environments improves, but device complexity increases
Solution Approach 1:
The patent combines multiple sensor types (acceleration sensors and orientation sensors) into an integrated sensing system. The acceleration sensors detect changes in the user's frame of reference, while orientation sensors track head position. By merging these sensor inputs and processing them together through a processing unit, the system achieves reliable tracking in non-static environments without requiring each sensor type to operate independently, thus managing complexity through integration.
3Measurement precision
If the reference orientation is continuously adapted towards head orientation, then virtual object placement remains accurate during movement, but processing requirements increase
Solution Approach 1:
The system performs preliminary detection of frame of reference changes using acceleration sensors before full head tracking is required. When acceleration beyond a threshold is detected, the system proactively adjusts the reference frame orientation in advance, preparing the tracking system for upcoming movements. This preliminary action reduces the processing burden during actual head tracking, as the reference frame is already partially adapted, requiring less computational power to maintain accuracy.
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 continuous and accurate head tracking in non-static environments, ensuring proper placement of virtual objects relative to the user, enhancing VR and AR experiences by maintaining virtual objects' stability and correct positioning during movement.
Implementation Method 1
one or more sensors (116) configured to operate independently of the head sensor and to provide data indicative of changes in a current frame of reference of the user
Data Source
AI summary
Computing a relative-head-orientation relative to a moving-reference. First and second data are received. The first data are indicative of a head-orientation of a head of a user. The second data are indicative of at least one of: a location, a motion, an orientation, a velocity and an acceleration of the user. A head-orientation is computed according to the first data. A moving-reference is updated by an adjustment toward the head-orientation, to produce an updated-moving-reference. The amount of adjustment is indicated by processing the second data. A relative-head-orientation is computed relative to the updated-moving-reference. Binaural audio is rendered in accordance with the relative-head-orientation.