Head-Mounted Display Head Tracking and Virtual Object Adjustment

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Solution Overview

Problem

Existing augmented reality (AR) systems face challenges in maintaining the accurate positioning of virtual objects relative to a user's head movements, especially when the user experiences head movements due to bumpy rides or accidental contact with the head-mounted display (HMD), leading to a disrupted AR experience.

Innovation Solution

The method involves tracking the head position of the user relative to the HMD using inward-facing cameras to detect and adjust the position of virtual objects, reducing their resolution and number if excessive head movement is detected, and providing notifications to realign the HMD.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the user wears a head-mounted display device, then the user can experience augmented reality environment, but head movements disrupt the positioning of virtual objects relative to the user's head

Engineering Contradiction:

Improvepositioning accuracy of virtual objectsVSAvoidtolerance to head movements

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system continuously tracks head movements using sensors and inward-facing cameras, providing real-time feedback to adjust the positioning of virtual objects. This closed-loop feedback mechanism detects head position changes and compensates for them by updating the virtual object coordinates, thereby maintaining reliable positioning despite head movements.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary tracking system consisting of sensors and cameras that mediate between the user's head movements and the virtual object positioning. This intermediary layer detects head position changes and translates them into appropriate adjustments of virtual object coordinates, resolving the conflict between head movement freedom and positioning accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the system tracks head position continuously, then the positioning accuracy of virtual objects is maintained, but the device complexity increases

Engineering Contradiction:

Improvehead position tracking accuracyVSAvoidtracking system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The inward-facing cameras originally intended for other purposes are repurposed to assist in head position tracking, making them multi-functional. This reduces the need for dedicated tracking components and lowers overall device complexity while maintaining measurement precision through the combined use of sensors and existing cameras.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the device's own inward-facing cameras and sensors to track head position, rather than requiring external tracking equipment. This self-service approach eliminates the need for additional external devices and reduces system complexity while achieving accurate head position measurement.

Inventive Principle:

Principle #25Self-service

3Stability of the object's composition

If the system reduces the number and resolution of virtual objects when excessive head movement is detected, then the AR experience consistency is maintained, but the quality of AR experience deteriorates

Engineering Contradiction:

ImproveAR experience consistencyVSAvoidvirtual object quality

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The system dynamically adjusts the number and resolution of virtual objects based on real-time head movement detection. When head movements are within acceptable thresholds, full-quality virtual objects are displayed. When excessive movement is detected, the system adaptively reduces virtual object complexity to maintain rendering performance and experience consistency, then restores full quality when stability returns.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes key parameters of virtual objects (number and resolution) in response to head movement conditions. This parameter adjustment allows the system to maintain AR experience consistency during unstable periods while preserving the ability to deliver high-quality experiences when the user's head is stable, effectively managing the trade-off between consistency and quality.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3014338B1Tracking head movement when wearing mobile device

Publication Date: 2018.07.25 MICROSOFT TECHNOLOGY LICENSING LLC

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AI summary

Methods for tracking the head position of an end user of a head-mounted display device (HMD) relative to the HMD are described. In some embodiments, the HMD may determine an initial head tracking vector associated with an initial head position of the end user relative to the HMD, determine one or more head tracking vectors corresponding with one or more subsequent head positions of the end user relative to the HMD, track head movements of the end user over time based on the initial head tracking vector and the one or more head tracking vectors, and adjust positions of virtual objects displayed to the end user based on the head movements. In some embodiments, the resolution and/or number of virtual objects generated and displayed to the end user may be modified based on a degree of head movement of the end user relative to the HMD.