RF Position Tracking Using Carrier Phase Difference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current augmented and virtual reality systems face challenges in accurately tracking objects with six degrees of freedom due to issues like smooth and accurate tracking of controllers, high latency, robustness problems when line-of-sight is obscured, and high system complexity and cost.
Innovation Solution
A position and orientation determining system using RF devices with a constellation of antennae and a processor to compute angles from carrier phase difference measurements, coupled with inertial data to accurately determine the position and orientation of one RF device relative to another, enabling robust and real-time tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical or mechanical tracking systems are used to track controller position and orientation, then tracking can be achieved, but the system complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex optical or mechanical tracking systems with an RF-based electromagnetic field sensing system. The HMD device uses RF antennae to detect the position and orientation of controllers through electromagnetic field interactions, eliminating the need for complex optical cameras, lasers, or mechanical encoders while achieving comparable or superior tracking accuracy.
2Loss of time
If traditional tracking systems are used, then position tracking can be achieved, but latency is high and real-time tracking is not achieved
Solution Approach 1:
The system implements continuous periodic RF signal transmission and reception between the HMD and controllers. The RF system continuously measures carrier phase differences and updates position calculations at high frequency, enabling real-time tracking with minimal latency. This periodic electromagnetic field sampling occurs much faster than traditional optical tracking refresh rates.
3Reliability
If line-of-sight based tracking is used, then tracking works when visible, but tracking becomes unreliable when line-of-sight is obscured
Solution Approach 1:
The patent introduces RF electromagnetic fields as an intermediary medium for tracking. Instead of requiring direct visual line-of-sight between cameras and trackers, the system uses RF waves that can penetrate walls and obstacles. The electromagnetic field serves as a mediator that carries position information through environments where optical lines of sight are blocked, maintaining tracking reliability.
4Measurement precision
If high-precision tracking components are used, then tracking accuracy improves, but system cost increases making it unsuitable for commercial applications
Solution Approach 1:
The HMD device performs multiple functions using the same RF hardware: it tracks controllers, provides spatial audio, and enables wireless communication. The RF antennae and signal processing circuitry serve universal purposes rather than dedicated tracking components, reducing overall system cost while maintaining high measurement precision through sophisticated signal processing algorithms.
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
The system achieves high-resolution position and orientation determination with low latency and robustness, suitable for commercial applications, reducing system complexity and cost while maintaining accurate tracking even when line-of-sight is obscured.
Implementation Method 1
determine a three-dimensional position of the first RF device relative to the second RF device based on computing at least two of three angles in the second RF device coordinate frame (XY, XZ and YZ) computed from carrier phase difference (CPD) measurements taken between each pair of the at least three receiving antennae when receiving a single RF signal transmitted from the at least one antenna of the first RF device
Data Source
AI summary
A position and orientation determining system includes a first radio frequency (RF) device including at least one antenna configured to receive and transmit RF signals, a first radio unit in communication with the at least one antenna, and an inertial measurement unit (IMU). The system further includes a second RF device includes a constellation of antennae including at least three receiving antennae, a second radio unit in communication with the constellation of antennae, and a processor configured to determine a three-dimensional position and three-axis angular orientation of the first RF device relative to the second RF device based on computing at least two of three angles in the second RF device coordinate frame (XY, XZ and YZ) computed from carrier phase difference (CPD) measurements taken between each pair of the at least three receiving antennae when receiving a single RF signal transmitted from the at least one antenna of the first RF device, and estimating a direction of a gravity vector generated by the IMU.