Unfused Pose Drift Correction for AR Totem Tracking
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Solution Overview
Problem
User interaction systems in augmented reality struggle to maintain the realistic pose of virtual objects relative to a totem in six degrees of freedom, leading to drift and jitter due to electromagnetic measurement noise and integration errors.
Innovation Solution
A user interaction system that includes an electromagnetic transmitter on a totem body, a totem inertial measurement unit, and a head unit with an electromagnetic receiver, processor, and vision algorithms to generate a fused pose by combining EM wave data, head unit pose, and totem IMU data, with a comparator to detect drift and a pose correction routine to reset the totem IMU location, ensuring accurate tracking of the virtual object's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic waves and IMU data are fused to generate pose information, then tracking accuracy is improved, but measurement noise and integration errors cause drift and jitter
Solution Approach 1:
The system continuously compares the fused pose with the unfused pose and uses the difference (drift) as feedback to correct the fused pose. The drift correction routine adjusts the fused pose based on the comparison result, creating a closed-loop feedback system that eliminates accumulated errors and maintains long-term pose accuracy.
Solution Approach 2:
The system combines two different measurement approaches (EM wave-based unfused pose and IMU-fused pose) into a composite solution. By merging the short-term accuracy of IMU fusion with the long-term stability of EM wave tracking through comparison and selective correction, the system achieves both precision and reliability.
2Reliability
If drift correction is applied by resetting fused pose to unfused pose, then long-term stability is improved, but frequent corrections may introduce jitter
Solution Approach 1:
The system applies drift correction selectively rather than continuously. By comparing the magnitude of drift against a threshold and only correcting when necessary, the system avoids over-correction that would cause jitter while still addressing significant drift issues. This partial action approach balances stability with smoothness.
3Measurement precision
If continuous comparison between fused and unfused pose is performed, then drift detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The system performs full pose comparison continuously but applies correction only when drift exceeds a threshold. This partial action strategy maintains accurate drift detection through continuous monitoring while reducing computational overhead by executing the expensive correction operation only when necessary.
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 effectively reduces jitter and maintains the virtual object's correct pose relative to the totem, enhancing the stability and accuracy of augmented reality experiences by correcting drift and ensuring precise alignment with the totem's movement.
Implementation Method 1
an electromagnetic (EM) transmitter on the totem body to transmit an electromagnetic (EM) wave
Implementation Method 2
a totem inertial measurement unit (IMU) located on the totem to generate a totem IMU signal due to movement of the totem
Data Source
AI summary
The invention relates generally to a user interaction system having a head unit for a user to wear and a totem that the user holds in their hand and determines the location of a virtual object that is seen by the user. A fusion routine generates a fused location of the totem in a world frame based on a combination of an EM wave and a totem IMU data. The fused pose may drift over time due to the sensor's model mismatch. An unfused pose determination modeler routinely establishes an unfused pose of the totem relative to the world frame. A drift is declared when a difference between the fused pose and the unfused pose is more than a predetermined maximum distance.