Relative Inertial Measurement with Visual Drift Correction
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Solution Overview
Problem
Conventional virtual reality and augmented reality systems fail to separate user motion from the motion of a reference frame, leading to nausea and sickness due to oculovestibular mismatch and erratic control, and visual inertial odometry algorithms malfunction in moving reference frames, causing drift errors.
Innovation Solution
A relative inertial measurement system with two inertial measurement devices, one coupled to the user and one to the reference frame, determines relative motion by subtracting reference frame motion from user device motion, using visual corrections to adjust and calibrate inertial measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional VR/AR devices use a single IMU to track user motion, then the device can determine user movement, but it cannot separate user motion from reference frame motion, causing oculovestibular mismatch and nausea
Solution Approach 1:
The system segments motion measurement into two independent components: a first IMU mounted on the user device measures combined user and reference frame motion, while a second IMU mounted on the reference frame measures only reference frame motion. The processor separates these measurements to isolate pure user motion, eliminating the oculovestibular mismatch that causes nausea.
Solution Approach 2:
The second IMU acts as an intermediary that measures reference frame motion independently. This intermediary measurement is then used to subtract reference frame motion from the first IMU's measurements, allowing accurate separation of user motion from reference frame motion and preventing the harmful oculovestibular mismatch.
2Measurement precision
If visual inertial odometry algorithms are used to correct drift errors, then positioning accuracy improves, but the algorithms malfunction in moving reference frames, causing over-compensation and erratic behavior
Solution Approach 1:
The system segments the motion measurement function between two IMUs, allowing the visual inertial odometry algorithm to operate on corrected relative motion data rather than raw combined data. This segmentation enables the algorithm to function reliably in moving reference frames by providing it with already-separated user motion measurements.
Solution Approach 2:
The system performs preliminary action by separating reference frame motion from user motion before the visual inertial odometry algorithm processes the data. This preliminary separation prevents the algorithm from malfunctioning due to moving reference frame effects, ensuring stable and reliable operation.
3Measurement precision
If a single high-frequency IMU is used for motion tracking, then motion detection sensitivity is high, but the device complexity and computational burden increase
Solution Approach 1:
The system uses two standard-frequency IMUs instead of one high-frequency IMU. Each IMU operates at standard frequency, reducing individual sensor complexity and computational burden while maintaining high overall measurement precision through the segmentation of motion measurement functions.
Data Source
AI summary
Methods and systems for relative inertial measurement may include a user device comprising an inertial measurement device and/or a camera. A second inertial measurement device may be configured to move with a reference frame. One or more processors may receive inertial measurements from the first and second inertial measurement devices and determine movement of the user device relative to the reference frame by comparing the received inertial measurements. Additionally reference objects in a view of a camera may be used to calibrate the determined motion of the user device within the reference frame.