Optical Reader Calibration Using Virtual Reference Targets
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Solution Overview
Problem
Existing vehicle optical scanning systems face challenges in calibrating optical readers when a vehicle is present between them, requiring the control station to be free of vehicles and necessitating frequent adjustments, which is inconvenient for mechanical operators.
Innovation Solution
The system includes optical image reader apparatuses with a target placed close to the image capturing device, allowing calibration even when a vehicle is interposed, using a plate-shaped element and support column with sliding wheels for easy positioning and a magnetic coupling system for quick attachment, enabling precise calibration and compensation for movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference targets are vertically fixed on optical readers and calibration is performed using targets fixed on opposite optical readers, then calibration precision can be achieved, but the control station cannot have vehicles present during calibration and frequent adjustments are required
Solution Approach 1:
A virtual reference target is introduced as an intermediary concept. Instead of requiring physical targets fixed on optical readers, the system uses a virtual target positioned at a predetermined location that can be detected by the optical reader. This mediator enables calibration without requiring vehicles to be removed from the control station, as the virtual target can be positioned and detected regardless of vehicle presence.
Solution Approach 2:
The patent creates a virtual copy of the reference target rather than relying on physical targets. The virtual reference target is digitally positioned at predetermined coordinates, allowing the calibration process to proceed without physical interference from vehicles in the control station. This digital copying eliminates the need for physical target placement and removal.
2Measurement precision
If optical readers are arranged to face lateral sides of the vehicle for three-dimensional imaging, then geometric parameters can be determined, but the system requires precise geometric characterisation of the optical readers that is sensitive to movements and thermal expansions
Solution Approach 1:
The system incorporates a feedback mechanism where the optical reader detects the virtual reference target and uses this information to determine its own position and orientation. The processing system continuously monitors the detection results and adjusts the geometric characterisation parameters accordingly, compensating for movements and thermal expansions in real-time.
Solution Approach 2:
The virtual reference target is pre-positioned at predetermined coordinates before the calibration process begins. This preliminary positioning establishes a stable reference frame that remains consistent even when the optical readers experience movements or thermal changes, providing a reliable basis for subsequent geometric parameter determination.
Data Source
AI summary
An optical scanning system for measuring and/or controlling a vehicle and/or parts of a vehicle, wherein the vehicle is arranged on a support surface. The optical scanning system comprises two optical reader apparatuses, which are arranged on said support surface, on opposite sides of the vehicle, and are provided with respective optical image capturing devices configured to provide respective data/signals encoding one or more images of the vehicle, an electronic system, which is designed to process the data/signals in order to construct one or more three-dimensional images of the vehicle. The optical image reader apparatuses each comprise a calibration target, which lies on an approximately horizontal support surface and is arranged immediately adjacent to the optical image capturing device of the relative optical image reader apparatus at a predetermined distance from it.