Vehicle Wheel Axis Determination via Structured Light
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Solution Overview
Problem
Existing methods for determining the axis of rotation and wheel geometry of a vehicle wheel are prone to inaccuracy and require complex setups, especially under dynamic conditions, and struggle to provide precise and reliable measurements with minimal effort.
Innovation Solution
A method using structured illumination and a 3D point cloud to calculate wheel normal vectors and derive the axis of rotation from spatial movement, employing a parametric surface model and deformable models for shape compensation, allowing for precise and robust measurements during wheel rotation and vehicle movement without the need for complex mechanical setups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mechanical measurement setups are used to determine wheel axis of rotation, then measurement reliability can be maintained, but device complexity and effort required increase significantly
Solution Approach 1:
The patent replaces complex mechanical measurement setups with an optical measurement system. A light pattern is projected onto the wheel and captured by an imaging sensor while the wheel rotates, eliminating the need for mechanical contact points or complex mechanical alignment devices. The axis of rotation is determined through optical triangulation and image evaluation, significantly reducing device complexity while maintaining measurement reliability.
Solution Approach 2:
The patent introduces a light pattern as an intermediary element between the measurement system and the wheel. The projected light pattern serves as a mediator that reflects off the wheel surface and provides measurement information when captured by the imaging sensor, enabling non-contact measurement without direct mechanical interaction with the wheel.
2Stability of the object's composition
If wheel measurements are taken while the vehicle is stationary on a roller test stand, then measurement stability is improved, but productivity and measurement time increase
Solution Approach 1:
The patent transitions from static wheel measurement to dynamic measurement. The wheel is measured while it is rotating on the vehicle, rather than requiring the vehicle to be stationary on a roller test stand. This dynamic measurement approach allows measurements to be taken during normal vehicle operation or movement, significantly improving productivity while the rotation provides sufficient stability for accurate optical capture.
Solution Approach 2:
The patent utilizes the periodic rotation of the wheel during measurement. The light pattern is projected and captured at specific intervals during the wheel's rotation cycle, allowing measurements to be taken across multiple rotational positions. This periodic sampling during rotation enables comprehensive measurement without requiring the wheel to be completely stationary, balancing stability with productivity.
3Ease of operation
If conventional wheel surface features are used for measurement reference, then ease of operation is maintained, but measurement precision decreases due to surface irregularities
Solution Approach 1:
The patent applies a structured light pattern with specific local qualities to the wheel surface for measurement reference. Instead of relying on the wheel's natural surface features, a controlled light pattern (such as lines or grids) is projected onto the wheel, creating artificial reference features with known geometric properties. This allows precise measurement of the axis of rotation while maintaining ease of operation, as the light pattern provides clear, distinguishable reference points regardless of the wheel's surface condition.
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 determination of the axis of rotation and wheel geometry with reduced effort, achieving accurate measurements by using structured lighting and 3D point clouds, independent of wheel surface features, and allowing for dynamic wheel positioning during vehicle movement.
Implementation Method 1
a light pattern is projected onto at least the wheel (2) while the wheel is turning and the light pattern reflected by the wheel is recorded by a calibrated imaging sensor system
Data Source
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AI summary
The invention relates to a method for determining the axis of rotation of a vehicle wheel (2), wherein a light pattern (15) is projected at least onto the wheel (2) during rotation of the wheel (2) and the light pattern (15', 15'') reflected by the wheel (2) is recorded by a calibrated imaging sensor system and evaluated in an evaluation device. In order to achieve an exact and robust measurement of the axis of rotation and optionally of the axle and wheel geometries, especially of a wheel of a vehicle driving past, a wheel-related 3D point cloud (20) is determined during evaluation and a parametric surface model of the wheel (2) is adapted thereto. Normal vectors of the wheel are calculated for various rotational positions of the wheel (2) to obtain the wheel axes (22) and the spatial displacement of the normal vector (22) of the wheel is used to calculate the vector of the axis of rotation as the axis of rotation (24).