Triaxial Electronic Compass Zenith Direction Correction
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Solution Overview
Problem
Conventional triaxial electronic compasses fail to precisely determine the direction of a photographic apparatus when the optical axis is oriented towards the zenith or close to it, leading to incorrect direction readings in celestial-object auto-tracking photography.
Innovation Solution
A method using a triaxial electronic compass with an inclination sensor, where the selection of geomagnetic sensor output values is switched based on elevation angles, and the deviation angle is calculated and corrected to accurately determine the direction, employing equations Δη=ArcTan(Tan(θ)/sin(h)) and A′=A+Δη to adjust for orientation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional triaxial electronic compass is used to determine the photographing direction, then the device complexity remains simple, but the measurement precision deteriorates when the optical axis is oriented towards the zenith
Solution Approach 1:
The patent divides the direction determination process into multiple segments: (1) obtaining elevation angle from inclination sensor, (2) selecting appropriate output values from 3-axis geomagnetic sensor based on elevation angle, (3) calculating deviation angle using specific formulas, and (4) correcting the determined direction. This segmentation allows precise direction determination at zenith by handling different elevation angle ranges separately, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent performs preliminary actions by first obtaining the elevation angle using the inclination sensor before determining the photographing direction. Based on the elevation angle, the system pre-selects which output values from the 3-axis geomagnetic sensor to use and calculates the deviation angle in advance. This preliminary action ensures that the correct calculation method is applied before final direction determination, improving precision without adding complex hardware.
2Measurement precision
If the selection of geomagnetic sensor output values is switched based on elevation angles, then the measurement precision improves for zenith orientation, but the device complexity increases due to additional switching logic
Solution Approach 1:
The patent implements dynamic selection of geomagnetic sensor output values based on the elevation angle. The system continuously monitors the elevation angle and dynamically switches between different output value selections from the 3-axis geomagnetic sensor. This dynamic adaptation allows the system to maintain high measurement precision across different orientations (horizontal vs. zenith) without requiring complex static control logic, as the switching is automatically driven by the elevation angle measurement.
3Measurement precision
If deviation angle calculation and correction is performed, then the measurement precision improves, but the loss of time increases due to additional calculation steps
Solution Approach 1:
The patent replaces complex mechanical or iterative correction methods with direct mathematical calculations. The deviation angle is calculated using closed-form formulas that incorporate the elevation angle and selected geomagnetic sensor outputs. This substitution of calculation-based methods eliminates the need for time-consuming iterative adjustments or mechanical calibration procedures, achieving high measurement precision while minimizing time loss.
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
This approach enables precise direction determination of the photographic apparatus' optical axis, even when tilted, ensuring accurate celestial-object tracking by correcting for deviations caused by changes in elevation angles, thereby improving the accuracy of direction readings.
Implementation Method 1
detects geomagnetism (the magnetism of the earth) through use of the 3-axis geomagnetic sensor
Implementation Method 2
the inclination sensor detects an inclination of the triaxial electronic compass
Data Source
AI summary
A method of determining a direction of a triaxial electronic compass oriented in a specific direction by using the triaxial electronic compass and an inclination sensor, the method includes obtaining an elevation angle of the specific direction from the inclination sensor to switch a selection of two output values from the three output values to another selection of two output values therefrom; determining a geomagnetic aspect from the two output values; obtaining a rotational angle about an axis extending in the specific direction from the inclination sensor; calculating a deviation angle of the direction of the triaxial electronic compass which is caused by the selection switching, in accordance with the elevation angle, the geomagnetic aspect and the rotational angle; and correcting the direction of the triaxial electronic compass in accordance with the deviation angle.