Angular Speed Derivation Using Quaternion Attitude and Pitch Threshold Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The accuracy of angular speed derivation using a triaxial gyro sensor is compromised due to sensitivity errors caused by roll and pitch angles, leading to poor position detection in vehicle navigation systems, especially when the vehicle is inclined.
Innovation Solution
An angular speed derivation device that converts initial attitudes from triaxial acceleration sensors into quaternion representation, updates attitudes using differential equations from gyro sensor outputs, and switches to monoaxial gyro sensor outputs when pitch angle differences exceed a threshold, thereby reducing errors and maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a triaxial gyro sensor is used to calculate absolute attitude angle by integrating angular speed, then the sensitivity error caused by roll and pitch is resolved, but errors in the angular speed of respective axes are integrated into the absolute attitude angle, deteriorating detection accuracy
Solution Approach 1:
The patent introduces an intermediary mechanism that uses triaxial acceleration sensor data to calculate pitch angle, which then serves to correct the triaxial gyro sensor outputs. This intermediary correction process prevents the direct integration of erroneous angular speed data into the absolute attitude angle, resolving the contradiction between utilizing triaxial gyro data and maintaining attitude calculation accuracy.
Solution Approach 2:
The system implements feedback by continuously monitoring the pitch angle derived from acceleration sensors and using this information to correct the gyro sensor measurements in real-time. This feedback loop ensures that errors in angular speed measurement do not accumulate in the integrated attitude angle calculation, thereby maintaining reliability while using triaxial gyro data.
2Measurement precision
If angular speed is corrected by pitch angle derived from triaxial acceleration sensor, then sensitivity drop when vehicle is inclined is resolved, but the complexity of the system increases
Solution Approach 1:
The patent makes the pitch angle calculation serve multiple functions: it corrects the triaxial gyro sensor measurements and is also used to dynamically select between different angular speed derivation methods. This multi-functionality reduces the need for separate correction mechanisms, thereby managing system complexity while improving measurement precision.
Solution Approach 2:
The system dynamically adjusts its operation mode based on the calculated pitch angle, switching between using corrected triaxial gyro data and alternative derivation methods. This dynamic adaptation allows the system to maintain accuracy across varying vehicle conditions without requiring complex fixed-structure correction systems for all possible scenarios.
3Device complexity
If monoaxial gyro sensor is used, then the system is simpler, but sensitivity error caused by roll and pitch deteriorates position detection accuracy
Solution Approach 1:
The patent introduces pitch angle calculation from acceleration sensors as an intermediary that corrects monoaxial gyro sensor outputs. This intermediary correction compensates for the sensitivity errors caused by roll and pitch, enabling the use of simpler monoaxial sensors while maintaining position detection accuracy comparable to or better than uncorrected triaxial systems.
Data Source
AI summary
An updating unit updates an attitude represented by quaternion by defining an initial attitude represented by quaternion as an initial value, and 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. The output unit outputs an angular speed derived based on an output value of a monoaxial gyro sensor, when a difference between a pitch angle derived based on the output value of the triaxial acceleration sensor and the output value of the second converter and a pitch angle from the second converter is equal to or larger than a threshold value.