Heading Computation Without Reference Axis
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Solution Overview
Problem
Current motion tracking techniques for mobile devices face inaccuracies and computational singularities when the reference axis approaches vertical, leading to increased complexity and accuracy degradation.
Innovation Solution
A system that uses an orientation sensor, an orientation analysis module, and a motion direction tracker module to compute the motion direction of a mobile device relative to an Earth-based coordinate system without relying on a reference axis, employing sensors like accelerometers, gyroscopes, and magnetometers, and satellite positioning systems to determine three-dimensional orientations and project motion directions onto a horizontal plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a reference axis is used in heading computation, then the computation structure is simple, but numerical singularities occur when the reference axis approaches vertical
Solution Approach 1:
The patent removes the reference axis from the computation system entirely. Instead of using a reference axis that causes singularities when vertical, the system directly computes heading from the motion vector and device orientation sensors, extracting only the necessary computational elements while eliminating the problematic reference axis component.
Solution Approach 2:
The patent changes the computational parameters from reference-axis-based angles to direct vector projections. By computing the heading as the angle between the horizontal projection of the motion vector and the horizontal projection of the device orientation, the system transforms the parameter space to avoid the singularity that occurs when the reference axis becomes vertical.
2Reliability
If the reference axis is replaced with another axis to avoid singularity, then computational stability is improved, but device complexity increases
Solution Approach 1:
Rather than replacing the reference axis with another axis (which would increase complexity), the patent extracts the essential heading information directly from sensor data through vector operations. The system computes heading by projecting the motion vector and device orientation onto the horizontal plane and calculating their relative angle, eliminating the need for any reference axis substitution mechanism.
3Measurement precision
If projection onto horizontal plane is used to compute heading, then accuracy is improved, but computational operations increase
Solution Approach 1:
The patent works in three-dimensional space throughout the computation process, using 3D vectors for motion and orientation. The horizontal projection is performed implicitly through vector mathematics rather than explicit 2D projection operations. This approach maintains accuracy by preserving the full 3D information while avoiding the computational overhead of separate projection and angle calculation steps.
Data Source
AI summary
Systems and methods are described for computing device motion direction and orientation. A system as described herein includes an orientation sensor configured to collect data relating to orientation of the mobile device; an orientation analysis module communicatively coupled to the orientation sensor and configured to determine a three-dimensional orientation of the mobile device relative to an Earth-based coordinate system based on the data collected by the orientation sensor; and a motion direction tracker module communicatively coupled to the orientation analysis module, configured to compute a first direction, that is a three-dimensional direction of motion of the mobile device relative to a coordinate system of the mobile device, and configured to compute a second direction, that is a direction of motion of the mobile device relative to the Earth-based coordinate system, based on the first direction using the three-dimensional orientation of the mobile device relative to the Earth-based coordinate system.