Angular Speed Derivation Device Using Quaternion Attitude Updates
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Solution Overview
Problem
The accuracy of angular speed derivation using a triaxial gyro sensor is compromised due to sensitivity errors caused by vehicle inclination, leading to poor position detection in navigation systems, especially when the vehicle is inclined or on slopes.
Innovation Solution
An angular speed derivation device that converts initial attitudes from triaxial acceleration sensors into quaternion representation, updates attitudes using differential equations with gyro sensor outputs, and adjusts derivation time based on variance values to reduce errors and improve accuracy, optionally switching to monoaxial gyro outputs when integral values or temperature variations exceed thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a triaxial gyro sensor is used to calculate absolute attitude angle, then the sensitivity error caused by roll and pitch is reduced, but errors in angular speed of respective axes are integrated into the absolute attitude angle, deteriorating detection accuracy
Solution Approach 1:
The patent segments the attitude calculation process into two independent parts: (1) calculating absolute attitude angle using triaxial gyro sensor outputs, and (2) calculating angular speed using only the yaw axis gyro sensor output. This segmentation prevents error propagation from triaxial gyro integration while maintaining accurate attitude detection, thus resolving the contradiction between improved attitude detection accuracy and deteriorated angular speed detection accuracy
Solution Approach 2:
The patent extracts only the necessary component (yaw axis angular speed) from the triaxial gyro sensor data for angular speed calculation, while using all three axes for attitude calculation. This selective extraction ensures that angular speed detection relies on a single, stable measurement source, preventing error integration while maintaining comprehensive attitude awareness
2Speed
If the derivation period is shortened to reduce integration error accumulation, then real-time performance improves, but measurement accuracy deteriorates due to increased noise impact
Solution Approach 1:
The patent changes the derivation period parameter dynamically based on vehicle speed conditions. When vehicle speed exceeds a threshold, a first (shorter) derivation period is used for real-time responsiveness. When vehicle speed is at or below the threshold, a second (longer) derivation period is used to reduce noise impact and improve measurement accuracy. This parameter adaptation resolves the contradiction between derivation speed and measurement precision
Data Source
AI summary
A first converter converts an initial attitude in an Euler angle representation into an initial attitude represented by quaternion. An updating unit updates an attitude represented by quaternion by defining the initial attitude represented by quaternion as an initial value, successively substituting output values of the triaxial gyro sensor. A second converter converts the attitude represented by quaternion into an attitude in the Euler angle representation. An angular speed derivation unit derives an angular speed based on a time-dependent change in the attitude in the Euler angle representation. A controller adjusts a period of time for derivation by an initial attitude derivation unit based on a variance value of the output value of the triaxial acceleration sensor or a variance value of the output value of the triaxial gyro sensor, when the speed is lower than a threshold value.