Virtual Rigid Framework for Sensor Calibration in AR Headsets
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Solution Overview
Problem
Designing Near-to-Eye Display (NED) devices like HMDs for AR/VR applications poses a challenge in maintaining sensor calibration accuracy over the device's lifetime, as traditional rigid support structures are bulky and restrictive, while software-based solutions are less accurate and resource-intensive.
Innovation Solution
Implementing a non-line-of-sight virtual rigid framework (VRF) with magnetic tracking and inertial measurement units to dynamically determine and correct sensor misalignment in real-time, allowing for more streamlined headset designs and improved sensor layout flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional rigid support structures are used to maintain sensor calibration accuracy, then sensor positioning stability is improved, but device bulkiness and design flexibility worsen
Solution Approach 1:
The patent replaces the mechanical rigid support structure with a magnetic field-based tracking system. Magnetic transmitters and receivers establish a virtual rigid framework that dynamically tracks sensor positions without requiring physical rigid connections, thereby reducing device bulkiness while maintaining calibration accuracy.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between sensors and the reference frame. Instead of direct mechanical coupling, magnetic transmitters and receivers mediate the positioning information, allowing sensors to be positioned flexibly while maintaining accurate calibration through field-based tracking.
2Device complexity
If software-based calibration solutions are used, then device complexity is reduced, but measurement accuracy and processing resource requirements worsen
Solution Approach 1:
The patent introduces magnetic fields as an intermediary to provide continuous, high-precision positioning data without complex software calibration algorithms. The magnetic VRF system directly measures sensor positions and orientations, eliminating the need for resource-intensive computational correction methods.
3Measurement precision
If magnetic field strength is increased to improve tracking accuracy at distance, then measurement precision is improved, but energy consumption and harmful electromagnetic effects worsen
Solution Approach 1:
The patent employs dynamic adjustment of transmitter power based on receiver distance and signal quality. The system continuously adapts transmission strength to maintain optimal signal-to-noise ratio, consuming minimal energy when sensors are close or signal quality is high, and increasing power only when needed for distance tracking.
Solution Approach 2:
The system dynamically changes magnetic field parameters (strength, frequency, modulation) based on operational conditions. By adjusting these parameters in real-time, the system maintains high tracking accuracy across varying distances while minimizing energy consumption and electromagnetic interference.
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 enables high-frequency correction of sensor misalignment, maintaining calibration accuracy and enabling more sophisticated and portable AR/VR applications with reduced bulkiness and increased innovation in sensor layout.
Implementation Method 1
a magnetic field sensor mounted on or proximate to a second sensor... to measure a parameter that varies with a position or orientation of the second sensor
Data Source
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AI summary
A technique for dynamically controlling performance parameters in a six degrees-of-freedom non-line-of-sight sensor subsystem disclosed. In certain embodiments, a magnetic field sensor is mounted on or proximate to an object to measure a parameter that varies with a position or orientation of the object, where the magnetic field sensor is part of a sensor calibration subsystem. The position or an orientation of the object is determined based on the parameter as indicated in an output of the magnetic field sensor. A receiver bandwidth and/or other operation parameter of the subsystem is dynamically adjusted during operation of the subsystem based on, for example, a transmitter-receiver distance or an operational state of the subsystem.