MEMS Gyro Array Common-Mode Error Separation
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Solution Overview
Problem
MEMS gyros used in spacecraft attitude determination suffer from significant common-mode noise and bias errors, limiting their accuracy and range of applications compared to traditional gyro technologies.
Innovation Solution
An array of four or more MEMS gyros is configured to separate and remove common-mode error effects, using a common-mode transformation and processor-based correction to enhance attitude estimation and pointing accuracy, while also reducing the need for precise power supplies and electronics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If MEMS gyros are used for spacecraft attitude determination, then cost, weight, and power consumption are reduced, but measurement precision deteriorates due to common-mode noise and bias errors
Solution Approach 1:
The patent segments the error sources by separating common-mode errors from individual gyro errors. By using multiple gyros (four or more) and applying a common-mode transformation, the system divides the total error into separable components that can be independently processed and removed, thereby improving measurement precision while maintaining the use of lightweight MEMS devices
Solution Approach 2:
The patent combines outputs from multiple MEMS gyros (four or more) into a unified measurement system. By merging the data from multiple sensors and applying collective processing (common-mode transformation followed by bias correction), the system achieves higher measurement precision than individual gyros could provide alone, while still using low-cost MEMS technology
2Device complexity
If MEMS gyros are used for spacecraft attitude determination, then device complexity is reduced, but measurement precision deteriorates due to common-mode noise and bias errors
Solution Approach 1:
The patent extracts common-mode errors from the gyro measurements through a mathematical transformation. By separating the common-mode component from individual gyro signals, the system removes a major source of measurement error without adding physical complexity to the gyro devices themselves, thereby improving precision while maintaining simple MEMS-based hardware
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously estimates and corrects for gyro biases using the array of multiple gyros. The common-mode transformation provides feedback information about systematic errors, which is then used to adjust and correct the measurements, improving precision through software-based feedback rather than hardware complexity
3Measurement precision
If traditional gyro technologies are used, then measurement precision is improved, but cost and weight increase
Solution Approach 1:
The patent uses multiple copies of low-cost MEMS gyros (four or more) to replicate the measurement function. By taking measurements from multiple identical, inexpensive sensors and processing them collectively through common-mode transformation and bias correction, the system achieves precision comparable to traditional gyros while maintaining the weight and cost advantages of MEMS technology
Data Source
AI summary
The present invention addresses performance limitation of gyros (e.g., MEMS gyros) by significantly reducing common-mode noise and bias effects. In one embodiment, an array of gyros, which may comprise four or more gyros, is configured so that common-mode error effects can be separated from the sensed rotational motion of the gyros and therefore removed. Removing the common-mode effects increases attitude estimation and spacecraft pointing accuracy, particularly during periods when the gyros must solely provide the attitude reference.