Inertial Heading Determination Using Dual-Mode Sensor Fusion
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Solution Overview
Problem
Existing methods for determining the direction of geographic North using inertial sensor modules are prone to errors due to gyroscope drift and accelerometer bias, especially when there is movement, requiring precise installation and expensive equipment.
Innovation Solution
A method that combines data from inertial sensor modules in North seeker mode and gyrocompass mode to calculate two heading values, with the difference between them used to discriminate and reduce errors, allowing for selection of the most precise value based on movement detection and statistical consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a north finder with a gyroscope is used to determine heading, then measurement precision is improved, but device complexity and installation requirements worsen due to the need for perfect stability and careful installation to avoid movement
Solution Approach 1:
The method segments the heading determination process into two distinct modes: north seeker mode (using only gyrometric data) and gyrocompass mode (using both accelerometric and gyrometric data). This segmentation allows the system to switch between different measurement strategies based on stability conditions, reducing the impact of installation complexity on overall performance
Solution Approach 2:
The system dynamically switches between north seeker mode and gyrocompass mode based on detected movement or instability. When movement is detected, the system transitions to gyrocompass mode which is more robust to movement, thereby maintaining measurement precision despite installation imperfections
2Reliability
If a gyrocompass mode using accelerometer data is used to determine heading, then reliability is improved by limiting errors from angular movement, but manufacturing precision requirements worsen due to the need for expensive high-precision accelerometers
Solution Approach 1:
The system uses accelerometric data partially, only when needed for gyrocompass mode operation. By combining this with north seeker mode that uses only gyrometric data, the system achieves reliability improvement without requiring accelerometers to operate at maximum precision continuously, thereby reducing manufacturing cost requirements
Solution Approach 2:
The system changes operational parameters by switching between two distinct operational modes. In north seeker mode, accelerometric data is not used for heading calculation. In gyrocompass mode, accelerometric data is used alongside gyrometric data. This parameter change allows the system to achieve reliability without requiring expensive high-precision accelerometers
3Ease of manufacture
If north seeker mode using only gyrometric data is used, then device cost is reduced, but measurement precision worsens due to gyroscope drift and sensitivity to movement
Solution Approach 1:
The system merges two different heading determination approaches: north seeker mode (low cost, gyroscope-only) and gyrocompass mode (higher cost, accelerometer-plus-gyroscope). By combining these modes and allowing dynamic switching between them, the system achieves both cost reduction and maintained precision, as the north seeker mode provides accurate measurements when stable while the gyrocompass mode corrects for drift and movement
4Reliability
If the system operates in gyrocompass mode continuously, then reliability is improved, but loss of energy worsens due to continuous processing of accelerometric data
Solution Approach 1:
The system performs periodic movement detection and mode switching rather than continuously operating in gyrocompass mode. By detecting movement periodically and switching modes based on conditions, the system maintains reliability when needed while reducing energy consumption during stable periods when north seeker mode suffices
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 method provides a precise heading determination while minimizing errors associated with gyroscope drift and accelerometer bias, maintaining accuracy without the need for expensive accelerometers, and automatically adjusting for movement.
Implementation Method 1
inertial sensor module in gyrocompass mode using data from the inertial sensor module
Implementation Method 2
inertial sensor module comprising three gyrometric measurement axes and three accelerometric measurement axes
Data Source
AI summary
The invention relates to a method for determining a heading in the direction of true north using an inertia-sensing module comprising three gyrometer measuring axes and three accelerometer measuring axes, said method including the following steps: using the data from the inertia-sensing module according to a north-seeking mode for obtaining a first heading value; using the data from the inertia-sensing module according to a gyrocompass mode for obtaining a second heading value; and determining the heading in the direction of true north using the first heading value and the second heading value.