MEMS Gyro North-Finding for Low-Cost Underground INS
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Solution Overview
Problem
Inertial navigation systems in underground mining vehicles face challenges in accurately determining the north direction due to the high bias repeatability and instability of low-cost MEMS gyroscopes, which limits their precision and reliability for navigation.
Innovation Solution
A north-finding system utilizing three-axis MEMS gyroscopes that estimates rotation rate biases in all three axes, correcting for inaccuracies and using the Earth rotation rate vector to calculate the vehicle's pose, thereby improving accuracy and reducing the need for complex mechanical structures like gimbals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If low-cost MEMS gyroscopes are used in inertial navigation systems, then the cost and device complexity are reduced, but the measurement precision and reliability deteriorate due to high bias repeatability and instability
Solution Approach 1:
The patent replaces complex mechanical north-finding structures (such as gimbals and mechanical rotation mechanisms) with an electronic/software-based bias correction system. The system uses computational algorithms to estimate and correct gyroscope biases, substituting mechanical complexity with electronic processing while maintaining or improving measurement precision.
Solution Approach 2:
The patent changes the operational parameters of the MEMS gyroscope by implementing a bias correction process that dynamically adjusts measurement parameters. The system estimates bias parameters through specific measurement sequences and applies corrections to the raw gyroscope data, thereby improving measurement precision without changing the physical gyroscope hardware.
2Measurement precision
If complex mechanical structures like gimbals are used to maintain accurate orientation, then the measurement precision improves, but the device complexity and cost increase
Solution Approach 1:
The patent replaces complex mechanical north-finding structures (such as gimbals and mechanical rotation mechanisms) with an electronic/software-based bias correction system. The system uses computational algorithms to estimate and correct gyroscope biases, substituting mechanical complexity with electronic processing while maintaining or improving measurement precision.
Solution Approach 2:
The patent extracts and removes the unnecessary mechanical components (gimbals, mechanical rotation stages) from the navigation system. By taking out these complex mechanical structures and replacing them with a simplified electronic bias correction approach, the system achieves the same or better precision with reduced complexity.
3Measurement precision
If high-precision gyroscopes are used to accurately determine north direction, then the measurement precision improves, but the cost and device complexity increase
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors gyroscope measurements, estimates biases through specific measurement sequences, and applies corrections to the raw data. This closed-loop feedback process compensates for the inherent instability of low-cost MEMS gyroscopes, improving both measurement precision and reliability without requiring expensive high-precision hardware.
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 solution provides a more accurate and cost-effective navigation system by compensating for the lower accuracy of MEMS gyroscopes, enabling continuous pose maintenance during motion and reducing the complexity of mechanical structures, thus enhancing navigation precision in underground mining environments.
Implementation Method 1
uses the Earth rotation rate vector to calculate the rotation rate bias about the rotation axis
Data Source
AI summary
This disclosure relates to an underground mining vehicle comprising a three-axis MEMS gyroscope rotatable about a rotation axis and a gyroscope interface that calculates a first rotation rate bias with respect to a first axis different to the rotation axis, a second rotation rate bias with respect to a second axis different to the first axis and different to the rotation axis, a rotation rate about the rotation axis based on the Earth rotation rate vector by correcting the rotational measurement data using the first rotation rate bias and the second rotation rate bias and a third rotation rate bias with respect to the rotation axis based on the calculated rotation rate about the rotation axis. A navigation unit receives the first rotation rate bias, the second rotation rate bias and the third rotation rate bias and calculates a pose of the vehicle.