Lidar Marker Detection via Intensity Thresholds
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Solution Overview
Problem
Existing methods for determining the position and orientation of mobile devices, such as partially automated vehicles or robots, in environments face challenges in reliability and complexity, particularly in areas with limited structure or dynamic objects, where traditional reflector markers and laser localization methods are not effective due to high reflectivity from objects like metal surfaces and reflective clothing.
Innovation Solution
A method using a subset of points with specific intensity thresholds to identify markers, where points with higher intensity than a first threshold are considered part of a marker, and those with lower intensity are adjacent, allowing for robust detection of markers even in environments with disruptive influences, and combining this approach with scan matching for accurate localization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reflector markers are used for laser localization, then the position and orientation can be determined, but the method becomes complex and unreliable in environments with high reflectivity objects
Solution Approach 1:
The patent changes the detection parameter from intensity threshold alone to a combination of intensity threshold and spatial distribution pattern. By analyzing both the intensity values and the geometric arrangement of high-intensity points, the system can distinguish true reflector markers from false reflections, thereby improving localization reliability while maintaining manageable complexity
Solution Approach 2:
The patent introduces an intermediary processing step that analyzes the spatial distribution pattern of high-intensity points before final marker identification. This intermediary analysis layer acts as a filter to eliminate false positives from reflective objects, resolving the contradiction between reliability and complexity
2Measurement precision
If reflector markers are placed throughout the environment, then localization accuracy improves, but the effort and complexity of marker placement increases significantly
Solution Approach 1:
The patent extracts the essential identification features (intensity threshold and spatial distribution pattern) from the complete marker placement system. By focusing detection on these specific features rather than requiring comprehensive marker coverage, the system achieves good localization precision with reduced marker placement effort
Solution Approach 2:
The patent applies partial action by using only the necessary subset of markers rather than placing markers throughout the entire environment. The selective detection based on intensity and spatial patterns allows localization with fewer markers, reducing placement effort while maintaining adequate precision
3Ease of manufacture
If natural contours via scan matching are used for localization, then marker placement effort is reduced, but reliability decreases in areas with limited structure or dynamic objects
Solution Approach 1:
The patent merges the advantages of both approaches by combining reflector marker detection with scan matching. The system first identifies reflector markers using intensity and spatial pattern analysis, then uses these markers to guide and validate scan matching results, achieving reliable localization with reduced marker placement effort
Solution Approach 2:
The patent segments the localization process into two parts: reflector marker identification (using intensity and spatial distribution) and position determination (using scan matching). This segmentation allows the system to leverage the strengths of each method while mitigating their weaknesses, improving reliability without requiring extensive marker placement
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
This method provides significantly improved reliability and reduced marker placement effort, enabling accurate determination of position and orientation in challenging environments, and can be adapted to different lidar sensor models, enhancing the robustness of marker detection and localization results.
Implementation Method 1
This can be achieved, for example, using laser distance measurement (e.g., with lidar sensors).
Implementation Method 2
These reflector markers can be detected by the laser scanner or lidar sensor because points measured on them are reflected with a significantly higher intensity than in the rest of the environment.
Data Source
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AI summary
The invention relates to a method for determining a position and/or orientation of a mobile device (100) in an environment (150) in which the mobile device (100) is moving or is intended to move, comprising: providing a set of points in the environment that have been determined from and relative to the mobile device (100), wherein each point is assigned an intensity, in particular a light intensity;and determine, based on the set of points, a subset of points that can be assigned to one or more markers (160) present in the environment, wherein points to be assigned to a marker (160) are determined according to at least one criterion, wherein the at least one criterion comprises that one or more points with an intensity higher than a first threshold lie within a first predetermined area, and that one or more points with an intensity lower than a second threshold lie within a second and/or third predetermined area, wherein the second and/or third predetermined area adjoins the first predetermined area;and wherein the subset of points, and in particular the one or more markers to which the points of the subset are assigned, are determined based on the one or more points with an intensity higher than the first threshold.