Car Navigation System Yaw Angle Correction
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Solution Overview
Problem
Conventional car navigation systems face reduced detection accuracy of vehicle position and heading angle due to sensor axis inclination and the failure to properly correct for lateral acceleration and body attitude when the navigation system casing is set at an angle, leading to incorrect yaw rate and distance measurements.
Innovation Solution
A car navigation system that includes a distance sensor, angular velocity sensor, acceleration sensor, and dedicated units for measuring body roll and pitch angles, as well as a yaw direction mounted angle detector to correct the sensor output and accurately determine the body attitude, thereby improving the accuracy of position and heading angle measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the navigation system casing is set in the car body with sensor detection axes askew, then the device complexity is reduced and ease of installation is improved, but the measurement precision of body attitude and heading angle deteriorates due to incorrect sensor output
Solution Approach 1:
The system performs preliminary detection of the mounted angle between the casing and car body, and pre-calculates the correction values for sensor output based on this detected angle. This preliminary action allows the system to compensate for the askew sensor axes without requiring precise physical alignment during installation.
Solution Approach 2:
The system changes the parameter of sensor output by applying correction values that depend on the mounted angle. By adjusting the correction parameters based on the detected orientation, the system maintains measurement precision even when the physical installation angle deviates from the ideal alignment.
2Device complexity
If the sensor detection axes are kept askew in the casing, then the device complexity is reduced, but the reliability of position and heading angle detection deteriorates due to uncorrected lateral acceleration components
Solution Approach 1:
The system uses feedback from the acceleration sensor to detect the mounted angle and generate correction values. The acceleration sensor output is used to determine the orientation state, which then feeds back into the correction calculation, creating a closed-loop system that maintains reliability without complex mechanical adjustments.
Solution Approach 2:
The system introduces an intermediary correction mechanism that processes the sensor output through mathematical corrections based on mounted angle. This intermediary correction layer bridges the gap between the simple askew installation and the requirement for accurate measurements, without adding complex mechanical structures.
3Device complexity
If conventional correction methods are used without detecting mounted angle, then the calculation process is simpler, but the measurement precision of angular velocity and acceleration deteriorates due to superimposed lateral acceleration components
Solution Approach 1:
The system performs preliminary detection of the mounted angle using acceleration sensor output, and pre-calculates the correction values based on this angle. This preliminary action allows the subsequent correction process to be more straightforward, as the correction parameters are determined in advance based on the detected orientation.
Solution Approach 2:
The system changes the correction parameters dynamically based on the mounted angle detected from acceleration sensor output. By adjusting the correction values according to the actual orientation, the system achieves higher measurement precision while maintaining a relatively simple calculation process that adapts to the installation conditions.
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
The system effectively corrects for sensor axis inclination and body attitude, enhancing the accuracy of angular velocity, acceleration, and distance measurements, even when the navigation system is set with rotations or tilts, thereby improving the overall detection accuracy of vehicle position and heading angle.
Implementation Method 1
an acceleration sensor (3) for detecting acceleration in a longitudinal direction of the casing on a horizontal plane
Implementation Method 2
an angular velocity sensor (1) for detecting angular velocity in a vertical direction of the casing
Implementation Method 3
a distance sensor (2) for outputting a pulse signal corresponding to a distance of vehicle movement
Data Source
AI summary
A car navigation system includes a distance sensor 2; an angular velocity sensor 1 for detecting angular velocity having a sensor detection axis in a vertical direction of a casing; an acceleration sensor 3 for detecting acceleration having a sensor detection axis in a back and forth direction of the casing on a horizontal plane; a body velocity and acceleration measuring unit 42 for measuring velocity and acceleration in the body direction of vehicle movement from the signal from the distance sensor; an angular velocity measuring unit 41 for measuring angular velocity from the signal from the angular velocity sensor; a body roll angle estimating unit 43 for estimating a body roll angle from the body direction of vehicle movement velocity and angular velocity; an acceleration sensor output estimating unit 45 for outputting, when the casing is set in the body with a rotation in a yaw direction, estimation values of the output signal of the acceleration sensor at every prescribed angle; and a yaw direction mounted angle detecting unit 46 for determining as a yaw direction mounted angle in the body an angle at a time when an estimated value is obtained which agrees most closely with a value remaining after subtracting from the signal from the acceleration sensor its offset component.