Three-Axis Sensor Calibration via Invariant Axis Detection
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Solution Overview
Problem
Existing motion estimation systems for inertial or magnetic sensors with three sensitivity axes face complexity in calibrating movements with six degrees of freedom, particularly in identifying a substantially invariant axis of rotation, which is crucial for accurate motion capture in various applications.
Innovation Solution
A method is developed to detect and validate an axis of rotation substantially invariant by acquiring physical measurements from the sensors, estimating the axis, calculating an indicator of variations, and comparing it with a noise threshold, allowing for the determination of a rotation matrix to transform sensor coordinates into a predetermined reference frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motion estimation systems use sensors with three sensitivity axes to capture six degrees of freedom, then measurement capability is improved, but system complexity and calibration difficulty increase
Solution Approach 1:
The patent extracts and identifies the substantially invariant axis of rotation from the six-degree-of-freedom motion data. By separating this invariant axis from the other motion components, the system reduces calibration complexity while maintaining full measurement capability. The invariant axis is identified through mathematical analysis of sensor data, allowing the system to handle six degrees of freedom without requiring full six-DOF calibration procedures.
2Measurement precision
If the system resolves systems of equations to find movement quantities, then measurement accuracy is improved, but computational complexity and time increase
Solution Approach 1:
The patent performs preliminary identification of the substantially invariant axis of rotation before solving the full system of equations for motion quantities. This pre-processing step provides a fixed reference that simplifies subsequent calculations, reducing the computational burden and time required to resolve the complete motion state while maintaining measurement accuracy.
3Productivity
If calibration processes assume known constraints in advance, then calibration speed is improved, but adaptability to different motion types decreases
Solution Approach 1:
The patent dynamically identifies the substantially invariant axis of rotation from the actual sensor data rather than assuming a fixed constraint in advance. This dynamic approach allows the calibration process to adapt to different motion types and configurations while maintaining efficient calibration speed. The system automatically determines the appropriate reference axis based on the observed motion characteristics.
Data Source
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AI summary
A method for detecting a substantially invariant axis of rotation of a moving object equipped with at least one three-axis inertial or magnetic sensor comprises the following steps: - acquisition (E10) of physical measurements along the three axes of sensitivity of said sensor; - estimation (E11-E15) of a substantially invariant axis of rotation in the space of said physical measurements; and - identification of said estimated axis as the substantially invariant axis of rotation of the motion. This method is used for calibrating a three-axis inertial or magnetic sensor.