Inertial Sensor Bias Estimation via Virtual Posture Angle
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Solution Overview
Problem
Inertial sensors, particularly multi-axis acceleration sensors, face challenges with misalignment errors and bias components, such as turn-on bias and temperature variations, which affect their accuracy and reliability in sensing applications.
Innovation Solution
A method and device for estimating bias values in inertial sensors by calculating a virtual posture angle assuming zero bias, allowing separation of gravitational and bias components in detection values, and correcting for temperature-dependent components, thereby improving accuracy in posture estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature compensation is performed to remove temperature-dependent components, then temperature stability is improved, but bias value magnitude remains considerable due to turn-on bias and other external influences
Solution Approach 1:
The patent performs bias value estimation as a preliminary action before actual measurement operations. By calculating the bias value in advance using the virtual posture angle method during a calibration phase, the system prepares corrected detection values that can be used in subsequent measurements, thereby addressing the bias issue before it affects measurement precision
Solution Approach 2:
The patent introduces a virtual posture angle as an intermediary concept to separate and estimate the bias component. By assuming a zero-bias virtual posture and comparing it with the actual posture, the system can isolate and correct the bias value without directly measuring it, thus improving measurement precision while maintaining temperature stability
2Measurement precision
If misalignment error correction is applied to improve detection accuracy, then manufacturing precision requirements increase, but device complexity increases
Solution Approach 1:
The patent enables the sensor system to self-correct its own errors through autonomous bias estimation and correction. The system uses its own detection values and the virtual posture angle calculation to automatically determine and compensate for misalignment errors, eliminating the need for external calibration equipment or complex manual adjustment mechanisms
Solution Approach 2:
The patent changes the parameter approach by introducing a virtual posture angle as an additional computational parameter. This virtual parameter serves as a mathematical tool to separate and correct the bias component, transforming a physical alignment problem into a computational solution that reduces device complexity
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 approach enables accurate estimation and correction of bias values, enhancing the reliability of inertial sensor outputs and improving posture estimation in various applications, including navigation systems.
Implementation Method 1
The detection values of the plural axes of the multi-axis acceleration sensor contain two components of a gravitational acceleration component in a detection axis direction and a bias component
Data Source
AI summary
A bias estimating method includes: calculating a virtual posture angle which is a posture angle with a bias which is assumed to be zero by the use of detection values of a plurality of axes in a calibration posture where one axis of a multi-axis acceleration sensor is parallel to the vertical direction; and estimating a bias value contained in the detection value of the axis using the detection value of the axis and the virtual posture angle.