Rotatable IMU Stage North Finding for Inertial Navigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional inertial navigation systems (INS) face challenges in accurately determining initial conditions under static conditions, requiring prolonged periods and high-quality, expensive IMUs, which limits their use to high-grade systems and results in accumulating errors over time.
Innovation Solution
The system employs a stage-based north finding method with a rotatable IMU on a stage positioned at multiple orientations, such as 0° and 180°, to improve accuracy and account for sensor errors, allowing for more accurate determination of true north and enabling navigation updates during static periods, even with lower-grade IMUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional gyro-compassing is used to determine initial conditions under static conditions, then the system can obtain navigation initialization, but the process requires prolonged periods and high-quality expensive IMUs, limiting use to high-grade systems
Solution Approach 1:
The patent applies dynamics by transitioning from static gyro-compassing to dynamic move-alignment. The system performs north-finding operations while the platform is in motion, eliminating the need for prolonged static periods. The method uses dynamic measurements combined with mathematical transformations to achieve accurate initial condition determination without requiring the platform to remain stationary for extended times.
Solution Approach 2:
The patent changes the operational parameters of the north-finding process by allowing platform motion during initialization. Instead of requiring static conditions with zero velocity and fixed orientation, the system accepts dynamic measurements with varying velocity and orientation, then uses computational methods to extract accurate initial conditions from these changed parameters.
2Ease of manufacture
If conventional gyro-compassing is used with lower-grade IMUs, then cost is reduced, but accuracy of initial condition determination deteriorates
Solution Approach 1:
The patent replaces the mechanical requirement for high-quality IMUs with a computational approach. By substituting sophisticated algorithms (move-alignment mathematics, dynamic measurements with transformation) for hardware excellence, the system achieves high accuracy with lower-grade, more cost-effective IMUs. The computational method compensates for sensor limitations.
Solution Approach 2:
The patent changes the operational parameters to enable lower-grade IMUs to achieve high accuracy. By allowing dynamic operation during initialization and using mathematical transformations to process the measurements, the system extracts maximum information from lower-quality sensors, achieving accuracy previously only available with expensive high-grade IMUs.
3Extent of automation
If the INS operates continuously without external references, then autonomy is maintained, but navigation errors accumulate over time
Solution Approach 1:
The patent implements self-service by enabling the INS to perform its own initialization and periodic updates using dynamic move-alignment operations. The system uses its own motion and sensors to determine accurate initial conditions and refresh navigation solutions without requiring external references, maintaining autonomy while improving reliability through self-correcting capabilities.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an improved Inertial Navigation System (INS), which comprises: (a) an INS unit which comprises: (a.1) an IMU which in turn comprises a set of at least three gyros and at least three accelerometers, all mounted on a rotatable stage; and (a.2) an INS algorithm for measuring the behavior of said gyros and said accelerometers during a mission, and calculating a navigation solution based on said measurements; and (b) a north finding determination unit, which comprises: (b.1) one or more from said IMU gyros and one or more from said IMU accelerometers; and (b.2) a north finding algorithm which utilizes measurements from said one or more north finding gyros and one or more north finding accelerometers during an initial conditions stationary state in which the stage is positioned in at least two separate stationary orientations, said north finding algorithm determines a north finding solution which is provided to the INS unit for initializing its said INS algorithm.