Tilted IMU Sensor Axes for In-Drive Vehicle Calibration
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Solution Overview
Problem
Existing inertial measurement units in vehicles require frequent calibration for accurate 3D position and orientation estimation, which is challenging due to limited dynamics in land vehicle movements, especially when sensors are aligned along main vehicle axes.
Innovation Solution
The inertial measurement unit employs tilted sensor axes, with each axis aligned orthogonally to the vehicle direction, allowing all axes to be calibrated through typical vehicle dynamics, using a combination of sensors like acceleration, rate-of-rotation, and additional sensing devices for data calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sensor axes are aligned along main vehicle axes, then device complexity is reduced and ease of manufacture is improved, but measurement precision and calibration reliability deteriorate due to limited dynamics in land vehicle movements
Solution Approach 1:
The patent introduces a tilted arrangement of sensor axes relative to the main vehicle axes. Instead of aligning sensors purely along the longitudinal, lateral, and vertical vehicle axes, the sensor axes are tilted by a specific angle (e.g., 45 degrees) to create a new dimensional orientation. This dimensional transformation allows the sensors to capture vehicle dynamics more effectively, enabling reliable calibration of all three sensor axes using typical land vehicle movements without requiring complex calibration procedures or additional device complexity
2Device complexity
If sensor axes are aligned along main vehicle axes, then device complexity is reduced, but calibration reliability worsens due to insufficient exposure to significant acceleration directions
Solution Approach 1:
The patent changes the orientation parameter of the sensor axes from alignment with main vehicle axes to a tilted arrangement. By modifying this geometric parameter, the sensors become exposed to significant acceleration directions (particularly longitudinal acceleration during propulsion and braking) more effectively. This parameter change enables reliable calibration without increasing device complexity or requiring complex calibration procedures
3Measurement precision
If sensor axes are tilted with respect to vehicle direction, then measurement precision and calibration reliability are improved, but device complexity increases
Solution Approach 1:
The patent employs an asymmetric tilted arrangement of sensor axes rather than symmetric alignment with vehicle axes. This asymmetric configuration, where sensor axes are tilted by a specific angle (e.g., 45 degrees) relative to the vehicle's longitudinal axis, creates optimal conditions for capturing vehicle dynamics. The asymmetry allows all three sensor axes to be calibrated using typical vehicle movements, improving measurement precision without requiring proportionally higher 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 reliable and accurate calibration of all sensor axes during driving, enhancing the accuracy of 3D position and orientation estimation without requiring significant changes to the vehicle structure or additional calibration methods.
Implementation Method 1
The basic principle of acceleration measurement is usually mass inertia. Thus, for example, a seismic mass under acceleration moves toward or counter to a sensing sensor element.
Implementation Method 2
The rate-of-rotation sensors are also referred to as a whole as a gyroscope.
Data Source
AI summary
A system for checking an inertial measurement unit of a vehicle, in particular a land vehicle, during driving includes the inertial measurement unit having: a first acceleration sensor configured to measure a translational acceleration along a first sensor axis and/or a first rate-of-rotation sensor configured to measure a rate of rotation about the first sensor axis and also a second acceleration sensor configured to measure a translational acceleration along a second sensor axis and/or a second rate-of-rotation sensor configured to measure a rate of rotation about the second sensor axis. A sensing device senses a movement of the vehicle in a first vehicle direction and/or about the first vehicle direction. Both the first sensor axis and the second sensor axis are tilted with respect to the first vehicle direction.