Posture Angle Calculation Using Conditional Gyro Filtering
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Solution Overview
Problem
Existing posture angle detection systems face errors due to bias changes in gyro sensors and temperature, which can lead to decreased sensitivity and inaccurate detection, especially when filtering processes assume zero angular velocity to prevent errors.
Innovation Solution
A posture angle calculation apparatus and method that acquires data from acceleration and gyro sensors, adjusts angular velocity values when the posture is stable, and sets angular velocity to zero when acceleration is above a reference and angular velocity is below a preset threshold, reducing detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filtering process that assumes the detected angular velocity is zero is performed to prevent errors in angular velocity detection, then measurement precision is improved, but sensitivity decreases making it difficult to detect posture angle in some cases
Solution Approach 1:
The patent applies dynamics by making the filtering process conditional rather than static. The system dynamically adjusts whether to apply the zero-angular-velocity assumption based on real-time detection of acceleration magnitude and posture change rate. When acceleration exceeds a threshold or posture changes rapidly, the filtering is suspended, allowing sensitive detection. When conditions are stable, filtering is applied to improve precision, thus resolving the contradiction between precision and sensitivity.
2Reliability
If the detected angular velocity is adjusted to zero when acceleration is high and angular velocity is low, then detection errors are reduced, but the system may fail to detect actual small angular velocities
Solution Approach 1:
The system uses feedback by continuously monitoring acceleration magnitude and posture change rate to determine when to apply or suspend the angular velocity filtering. This feedback mechanism ensures that the zero-angular-velocity assumption is only applied when reliable (high acceleration, low angular velocity indicating stability), and suspended when actual motion may be present, thus maintaining both reliability and measurement precision.
3Ease of operation
If gyro sensor data is used directly without filtering, then sensitivity is maintained, but detection errors occur due to bias output changes and temperature variations
Solution Approach 1:
The patent applies parameter changes by modifying the processing of angular velocity data based on the state of the system. Instead of using a fixed filtering approach, the system changes the processing parameter (whether to apply zero-velocity assumption) based on detected acceleration and posture change rate. This allows the system to maintain sensitivity during dynamic conditions while improving accuracy during stable conditions, resolving the contradiction between sensitivity and measurement precision.
Data Source
AI summary
A posture angle calculation apparatus 170 includes an acquisition unit 171 configured to acquire an output of an acceleration sensor 151 installed to output acceleration of a moving apparatus that moves along a moving surface in a vertical axis direction with respect to the moving surface and to acquire an output of a gyro sensor 152 installed to output an angular velocity about the vertical axis. The posture angle calculation apparatus 170 further includes a calculation unit 172 configured to assume, when the acceleration is larger than reference acceleration Rg, and the angular velocity is smaller than a preset reference angular velocity Rw, the angular velocity ωz is zero and calculate a posture angle of the moving apparatus about the vertical axis. The posture angle calculation apparatus 170 further includes an output unit 173 configured to output data of the calculated posture angle.