Vehicle IMU Calibration Using Level Sensors for Misalignment
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Solution Overview
Problem
Existing inertial measurement sensor systems in vehicles suffer from misalignment and offset errors due to incorrect installation and external influences, leading to inaccurate measurements and limiting their usability in applications like vehicle dynamics control and augmented reality.
Innovation Solution
A method for calibrating inertial measurement sensors during vehicle operation using vehicle-level sensors to determine misalignment and offset errors, allowing automatic and cost-effective calibration without the need for controlled conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a special measurement set-up is used to provide predefined accelerations and rotation rates for calibration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The calibration method enables the inertial measurement sensor system to calibrate itself using data from other sensors already present in the vehicle (wheel speed sensors, level sensors, headlamp adjustment sensors). The system uses naturally occurring vehicle movements and states during normal operation to determine offset errors and misalignments, eliminating the need for external calibration equipment.
Solution Approach 2:
The patent uses intermediate sensors as mediators to transfer reference information to the inertial measurement sensor system. Wheel speed sensors provide reference data for yaw rate calibration, level sensors provide reference for pitch angle calibration, and headlamp adjustment sensors provide reference for alignment calibration. These intermediaries enable indirect calibration without direct measurement equipment.
2Measurement precision
If a special measurement set-up is used for comprehensive calibration, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The calibration process operates continuously during vehicle operation rather than requiring a separate calibration step. The system continuously collects sensor data, determines offset errors and misalignments, and updates calibration parameters in real-time during normal driving, making the calibration process ongoing and eliminating dedicated calibration time.
Solution Approach 2:
The system performs preliminary calibration actions by continuously preparing and updating calibration data during vehicle operation. The calibration information is determined in advance during normal driving and stored for immediate use, so that when calibration is needed, it is already available without requiring additional time.
3Ease of operation
If long-term comparison of measured values is used to determine offset errors, then ease of operation is improved, but measurement precision deteriorates due to external influences
Solution Approach 1:
The system uses feedback from multiple sensors to continuously monitor and correct offset errors. Wheel speed sensor data provides feedback for yaw rate calibration, level sensor data provides feedback for pitch angle calibration, and headlamp adjustment sensor data provides feedback for alignment calibration. This multi-source feedback mechanism maintains precision while keeping operation simple.
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 and reliable calibration of inertial sensors by iteratively determining misalignment and offset errors, reducing the need for costly and time-consuming calibration procedures and improving sensor accuracy for vehicle dynamics and headlamp range control.
Implementation Method 1
the offset error estimation already attempts to compensate for the effect of the installation position of the sensor. As the amount of gravity is known from the position of the vehicle on the earth, excess acceleration amounts in a stationary situation are offset-related.
Data Source
AI summary
An inertial measurement sensor system of a vehicle is calibrated during a driving operation of the vehicle and is based on a determination of a misalignment of a sensor coordinate system of the inertial measurement sensor system with respect to a vehicle coordinate system. The determination of the misalignment is interrupted in situations in which a level deviation from a reference level exceeding a predetermined threshold value is determined by means of at least one of the vehicle's own level sensors.