IMU Posture Estimation with Angular Velocity Range Checking

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Solution Overview

Problem

Existing posture estimation methods using inertial measurement units (IMUs) suffer from bias errors and inaccuracies when angular velocity sensors output values fall outside their effective range, leading to decreased accuracy in estimating object posture.

Innovation Solution

A posture estimation method that adjusts error information by determining whether the output of the angular velocity sensor is within an effective range, increasing posture error components and reducing correlation components during periods when the sensor is out of range, and using an extended Kalman filter to correct predicted posture information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the output of the angular velocity sensor is used for posture estimation without range checking, then the estimation process continues uninterrupted, but the accuracy decreases when the sensor output exceeds the effective range

Engineering Contradiction:

Improveposture estimation reliabilityVSAvoidposture estimation accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The system performs preliminary checking of sensor output ranges before using the data for posture estimation. When the angular velocity sensor output exceeds the effective range, the system proactively increases the posture error component and reduces correlation components in advance, preventing accuracy degradation before it occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors the sensor output range and provides feedback to adjust the error information in real-time. When the sensor output is within the effective range, normal estimation proceeds; when it exceeds the range, the system feedback-adjusts the error covariance matrix to maintain reliable posture estimation despite the out-of-range condition.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If the correlation component between error components is maintained during off-scale conditions, then the error model remains consistent, but the posture estimation accuracy deteriorates due to propagated errors

Engineering Contradiction:

Improveerror model consistencyVSAvoidposture estimation accuracy

Core Design Contradiction:

Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The system dynamically changes the parameters of the error covariance matrix based on sensor operating conditions. During off-scale conditions, it increases the posture error component parameter and reduces the correlation component parameters, adapting the error model to reflect the degraded sensor performance and preventing error propagation that would otherwise deteriorate accuracy.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12606178B2Posture estimation method, posture estimation device, and vehicle

Publication Date: 2026.04.21 SEIKO EPSON CORP

AI summary

A posture estimation method includes calculating a posture change amount of an object based on an output of an angular velocity sensor, predicting posture information of the object by using the posture change amount, adjusting error information in a manner of determining whether or not the output of the angular velocity sensor is within an effective range and, when it is determined that the output of the angular velocity sensor is not within the effective range, increasing a posture error component in error information and reducing a correlation component between the posture error component and an error component other than the posture error component in the error information, and correcting the predicted posture information of the object based on the error information.