3D Optical Axle Geometry Measurement
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Solution Overview
Problem
Current methods for determining vehicle axle geometry, particularly steering geometry, suffer from measurement errors due to reliance on limited data points, leading to inaccuracies in calculating spread angle, caster angle, caster offset, and kingpin offset during axle alignment.
Innovation Solution
A 3D measurement method that calculates the parameters of the steering axis using a kinematic model, determining the axis of rotation and center of rotation via 3D wheel position measurements, allowing for direct calculation of steering axis characteristics without toe and camber value determination, and incorporating optical recording and transformation into a fixed vehicle coordinate system for enhanced accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional methods measure only two individual toe and camber values during wheel steering movement, then the measurement process is simple, but the calculation of spread angle and caster angle results in significant errors
Solution Approach 1:
The patent replaces traditional mechanical measurement systems (toe and camber meters) with an optical 3D measurement system using cameras to capture wheel position coordinates. This substitution enables continuous 3D recording of wheel movement, providing multiple measurement points that significantly improve the accuracy of spread angle and caster angle calculations while eliminating the limitations of two-point mechanical measurement.
Solution Approach 2:
The patent transitions from 2D measurement (toe and camber angles in a plane) to 3D measurement by recording the spatial coordinates of wheel positions during steering movement. This dimensional expansion allows for more comprehensive data collection throughout the steering range, enabling more accurate determination of steering geometry characteristics through multi-point 3D analysis.
2Measurement precision
If polynomial fitting is used to link multiple toe and camber measurements, then measurement accuracy increases, but the complexity of data processing increases
Solution Approach 1:
The patent replaces complex polynomial fitting procedures with a more direct approach using 3D coordinate data from optical measurement. By capturing wheel position in three-dimensional space throughout the steering movement, the system obtains sufficient data points that can be processed through coordinate transformation and geometric calculation, simplifying the overall data processing while maintaining high accuracy.
3Loss of information
If optical 3D recording of wheel movement is implemented, then complete 3D position and alignment data is obtained, but the measurement system becomes more complex
Solution Approach 1:
The patent employs optical measurement systems with multi-functional capabilities that can simultaneously capture wheel position, orientation, and movement trajectory in 3D space. The camera system serves multiple purposes: recording spatial coordinates, determining wheel attitude angles, and tracking steering movement throughout the measurement process, thereby reducing the need for separate measurement devices and minimizing overall system complexity.
Data Source
AI summary
A method for determining characteristics of an axle geometry of a vehicle including the following: steering a wheel mounted on an axle of the vehicle to various steering positions having different steering angles; determining the spatial position of the wheel at the different steering positions; determining the particular axis of rotation of the wheel in the different steering positions from the results of the determination of the spatial position; modeling a parametric model of the steering axis; adapting the parametric model of the steering axis to the axes of rotation of the wheel determined from the measurement of the spatial position; and determining characteristics of the axle geometry from the adapted parametric model of the steering axis.