Laser Scanner Alignment Using Camera Road Model Overlay
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Solution Overview
Problem
Existing methods for aligning laser scanners alongside roadways are complex and require known installation heights, making it difficult to set pitching angles and azimuth angles, especially for mobile devices with varying installation heights, and do not allow for reliable measurement at non-horizontal alignments.
Innovation Solution
A method using a camera fixedly connected to the laser scanner to visualize a road model on a display, allowing the scanner to be aligned at a predefined acute azimuth angle and pitching angle dependent on the installation height, with adjustments made through pulse time-of-flight measurements and trigonometric calculations to ensure optimal measurement range alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the laser scanner is installed at a different installation height with respect to the roadway margin, then the laser scanner can adapt to different ground heights outside the roadway, but the alignment with respect to the roadway margin and roadway surface becomes more complex
Solution Approach 1:
The patent applies parameter changes by adjusting the pitching angle based on the installation height. The control unit calculates the appropriate pitching angle from stored reference values corresponding to different installation heights, allowing the laser scanner to maintain optimal alignment across varying heights without increasing alignment complexity
Solution Approach 2:
The patent replaces complex mechanical alignment procedures with an automated optical and computational system. The camera captures images of the roadway, the control unit processes these images to determine installation height and calculate the required pitching angle, and the drive unit automatically adjusts the scanner's orientation, eliminating the need for manual mechanical alignment
2Area of stationary object
If the laser scanner is installed at a greater installation height, then the measurement range can cover more area, but the pitching angle setting becomes more difficult without known installation height
Solution Approach 1:
The system performs self-measurement by using the camera to capture images of the roadway and automatically determining the installation height from these images. The control unit processes the image data to calculate the scanner's height above the roadway surface, eliminating the need for external measurement tools or pre-known installation height information
Solution Approach 2:
The patent introduces a camera as an intermediary device to indirectly measure the installation height. Instead of directly measuring the height, the camera captures visual information about the roadway and scanner position, which the control unit then processes to derive the installation height and determine the appropriate pitching angle
3Ease of operation
If the measurement range is aligned horizontally with the roadway surface, then the alignment is simple, but reliable measurement is not ensured at greater installation heights
Solution Approach 1:
The patent implements dynamic alignment by making the pitching angle adjustable based on installation height rather than fixed at horizontal. The system automatically determines the optimal pitching angle from stored reference values and adjusts the scanner accordingly, ensuring reliable measurements across different installation heights while maintaining operational simplicity through automation
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 straightforward and reliable alignment of laser scanners at varying installation heights with minimal complexity, ensuring accurate vehicle detection and measurement range optimization without requiring special aids or known installation heights.
Implementation Method 1
By means of the pulse time-of-flight measurement, from the reflection signals that arise as a result of reflection of the pulsed laser beam at areas (reflection points) of vehicles travelling through the measurement range, the distance of the reflection point is ascertained
Implementation Method 2
from the reflection signals that arise as a result of reflection of the pulsed laser beam at areas (reflection points) of vehicles
Implementation Method 3
By means of a scanner mirror that rotates or pivots about a scanning axis, a pulsed laser beam coming from a laser source is deflected, within a predefined scanning angle range
Data Source
AI summary
A method for aligning a measuring device installed alongside a roadway at an unknown installation height, the measuring device including a laser scanner, a camera and a display. A camera image generated by the camera is inserted into the display and superimposed by a road model, formed from a multiplicity of straight lines running towards an intersection point. The measuring device is subsequently rotated and tilted, as a result of which the camera image is rotated and shifted on the display, until the images of the roadway margins and edges running parallel thereto are in alignment at the intersection point.