Vehicle Pose Estimation Using IMU Gravity Vector Separation

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Solution Overview

Problem

Existing methods struggle to accurately determine the roll angle of a vehicle while traveling on straight roads, leading to errors in localization and mapping due to incorrect assumptions about the vehicle's orientation relative to the ground level, which is often inclined.

Innovation Solution

A device and method that utilize an inertial measurement unit (IMU) to measure the total acceleration vector, separate the dynamic component from the gravitational component, and estimate the direction of the gravity vector to determine the roll angle, using a sliding window method for smoothing and incorporating this data into a graph SLAM algorithm for precise localization and mapping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the vehicle always moves on all four wheels parallel to ground level is assumed, then the calculation is simplified, but the localization and mapping accuracy deteriorates due to road inclines

Engineering Contradiction:

Improvecalculation complexityVSAvoidlocalization and mapping accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the parameter being measured from the simplified assumption of zero roll angle to the actual roll angle determined by IMU gravity vector measurements. This allows the system to account for road inclines and camber, improving localization and mapping accuracy without excessive computational complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical assumption-based approach with a sensor-based measurement approach using IMU to directly measure the gravity vector and determine the actual roll angle, substituting physical measurement for theoretical assumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If GNSS and odometry measurements are used alone, then the system is simple, but the roll angle cannot be determined on linear trajectories

Engineering Contradiction:

Improvesensor system complexityVSAvoidroll angle information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The patent merges IMU gravity vector measurements with existing GNSS and odometry data in a graph SLAM framework. This combination allows the system to determine absolute roll angle information that was previously unavailable from GNSS and odometry alone, while maintaining a unified and efficient processing architecture.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If IMU measurements are processed without separating dynamic and gravitational components, then processing is simpler, but roll angle determination becomes inaccurate during vehicle acceleration

Engineering Contradiction:

Improveprocessing complexityVSAvoidgravity vector estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the total acceleration vector measured by the IMU into two distinct components: the dynamic acceleration component (from vehicle motion) and the gravitational component (from Earth's gravity). This segmentation is achieved through graph SLAM optimization that separates these effects, allowing accurate determination of the gravity vector direction and thus the roll angle even during vehicle acceleration.

Inventive Principle:

Principle #1Segmentation

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

Enables precise determination of the vehicle's roll angle, improving the accuracy of localization and mapping by reducing errors caused by incorrect assumptions about vehicle orientation, particularly on inclined roads.

Implementation Method 1

determine a measured value of an acceleration vector of the vehicle... determine a value of a dynamic component of the measured value of the acceleration vector that is brought about by a movement of the vehicle... determine, on the basis of the measured value of the acceleration vector and on the basis of the value of the dynamic component, an estimate of a gravity vector

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS12528474B2Method and device for pose data relating to pose of a vehicle

Publication Date: 2026.01.20 BAYERISCHE MOTOREN WERKE AG

AI summary

A device for determining positional information relating to the position of a vehicle is configured to determine a measured value of an acceleration vector of the vehicle, and to determine a value of a dynamic component of the measured value of the acceleration vector caused by a movement of the vehicle. The device is further configured to determine an estimated value of the gravity vector based on the measured value of the acceleration vector and based on the value of the dynamic component, and to determine positional data relating to the position of the vehicle based on the estimated value of the gravity vector.