Monocular Chassis Measurement Using Coded Markers
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Solution Overview
Problem
Existing wheel alignment systems are complex, expensive, and prone to measurement errors due to high-precision optical targets that can be damaged or deformed, leading to uncontrollable measuring errors.
Innovation Solution
A method and device using four monocular image recording devices with known relative positions, allowing for 3D reconstruction of wheel geometry without the need for high-precision targets or additional distance measuring sensors, utilizing natural wheel features and enabling cost-effective and accurate wheel alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If binocular (stereo) image recording devices are used, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses monocular image recording devices that capture images of measurement targets with artificially added depth information through stereoscopic markers. Instead of using complex binocular cameras, the system creates a virtual stereo effect by placing coded markers on the measurement target that encode depth information, allowing a single camera to capture three-dimensional measurement data through image processing of these coded patterns.
2Measurement precision
If high-precision measurement targets with control point fields are used, then measurement accuracy is improved, but manufacturing cost increases and reliability decreases
Solution Approach 1:
The patent replaces expensive, fragile high-precision measurement targets with simple, durable alternatives. The measurement targets can be ordinary objects or even the vehicle components themselves, marked with coded patterns that can be applied through printing or attachment. These targets are much more resistant to damage and deformation in workshop environments while still providing accurate measurement data through the coded marker system.
3Measurement precision
If high-precision measurement targets are used, then measurement accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The measurement targets are manufactured as simple objects with printed or attached coded patterns rather than expensive precision-machined components. The coded markers can be applied to various surfaces using conventional printing or attachment methods, making the targets inexpensive to produce and replace if damaged.
4Device complexity
If monocular image recording devices are used, then device complexity and cost are reduced, but measurement precision deteriorates
Solution Approach 1:
The patent introduces coded markers as an intermediary element between the monocular camera and the measurement target. These markers contain encoded depth and position information that the single camera captures and decodes through image processing algorithms, effectively mediating the transformation from 2D image capture to 3D measurement data without requiring binocular vision hardware.
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 solution provides reliable, cost-effective, and accurate wheel alignment by eliminating the need for expensive optical targets and reducing measurement errors, while allowing for easy implementation and use in various workshop conditions.
Implementation Method 1
By performing local 3D reconstructions with a local scale, the translation vectors, the rotation vectors, the wheel rotation angles between the run-in positions and the main measurement positions, as well as the wheel rotation centers and the wheel axles of the wheels can be determined from the captured images
Data Source
AI summary
The method according to the invention for measuring a chassis comprises the steps of providing a chassis measuring system having four measuring heads (2, 4, 14, 16) arranged in known positions relative to each other, each of which has a monocular imaging device (22, 24, 26, 28), wherein the relative position of the measuring heads (2, 4, 14, 16) to each other is known, and wherein the distance (dVA) of the front measuring heads (2, 4) to each other differs from the distance (dHA) of the rear measuring heads (14, 16) to each other; capturing a front wheel (6, 8) or a measuring target arranged thereon in at least one first positioning location of the vehicle (1) by way of the rear measuring heads (14, 16); capturing the four wheels (6, 8, 10, 12) or the measuring targets arranged thereon by way of each of the four measuring heads (2, 4, 14, 16) in a first main measuring position and in a second main measuring position of the vehicle (1); carrying out local 3D reconstructions for determining the translation vectors (t1, t2, t3, t4), the rotation vectors (R1, R2, R3, R4) and the rotational angles of the wheel among said positions and the wheel rotational centers and the wheel rotational axes of the wheels (6, 8, 10, 12) from the captured images of the wheels (6, 8, 10, 12) or the measuring targets attached thereon; adapting the local scales to a common, global scale by the driving movement; transmitting the global scale from the main measurement to the positioning measurement; determining an absolute scale for the measuring heads (2, 4, 14, 16) from the measurements of the front wheels (6, 8) or of the measuring targets attached thereon in the positioning locations and in the main measuring positions; determining the measuring parameters of the chassis of the vehicle (1), particularly camber, individual and/or total track.