2D Laser Scanner Ground Plane Localization
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Solution Overview
Problem
Current localization methods for vehicles require expensive 3D laser sensors and continuous GPS data, making them impractical for cost-effective implementation, especially in areas with poor GPS reception, and are inadequate for handling combinations of roll, pitch, ground strikes, and environmental features like hedgerows and slopes.
Innovation Solution
A method using a single push-broom 2D laser scanner that generates a small 3D swathe of laser data, leveraging a prior 3D survey, by calibrating and matching the data with existing 3D point clouds using probabilistic mappings and Kullback-Leibler divergence to align new and existing point clouds, adjusting for bias factors in velocity measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive 3D laser sensors and DGPS systems are used, then localization precision is improved, but device cost and complexity increase
Solution Approach 1:
The patent replaces expensive, complex 3D laser sensors with a cheap 2D laser scanner that can be easily replaced or recalibrated. The system uses a single 2D scanner mounted on the vehicle to capture ground-plane reflections, eliminating the need for costly Velodyne-style 3D sensors while maintaining sufficient localization accuracy through statistical matching algorithms.
Solution Approach 2:
The patent creates a simplified 2D representation (copy) of the environment by projecting 3D point cloud data onto the ground plane. This 2D ground-plane map serves as a cheaper alternative to full 3D environmental models, reducing computational complexity and sensor requirements while preserving essential localization information.
2Measurement precision
If 3D laser sensors are used to generate accurate environmental maps, then localization accuracy is improved, but cost increases
Solution Approach 1:
The system uses an inexpensive 2D laser scanner instead of expensive 3D laser sensors to capture environmental data. The scanner is mounted to face downward at a specific angle to capture reflections from the ground plane, providing sufficient localization data without requiring costly hardware.
Solution Approach 2:
The patent extracts only the essential information needed for localization by projecting 3D point cloud data onto the 2D ground plane. This extraction process removes unnecessary 3D dimensional data, reducing computational requirements and enabling the use of cheaper 2D scanners while maintaining localization accuracy.
3Loss of information
If continuous GPS data is used for localization, then position estimation is improved, but reliability deteriorates in areas with poor GPS reception
Solution Approach 1:
The patent introduces an intermediary ground-plane reflection mechanism between the laser scanner and the environment. By capturing reflections from the ground surface, the system obtains localization data that is independent of GPS signals, enabling reliable operation in areas with poor GPS reception through a different physical measurement modality.
4Device complexity
If simple 2D scan matching is used, then device complexity is reduced, but measurement precision deteriorates due to roll, pitch, and ground effects
Solution Approach 1:
The patent transitions from traditional 2D horizontal scan matching to 2D ground-plane vertical scan matching. By mounting the laser scanner to face downward and capturing ground-plane reflections, the system creates a vertical 2D measurement dimension that is immune to roll and pitch errors, fundamentally changing the measurement geometry to eliminate susceptibility to vehicle orientation changes.
Solution Approach 2:
The system focuses measurements locally on the ground plane beneath the vehicle rather than attempting to match broad 2D horizontal features. This localized ground-plane approach captures immediate environmental characteristics that are less affected by distant hedgerows, verges, and slopes, improving precision through targeted local measurement.
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 vehicle localization with reduced costs and improved accuracy, even in areas with limited GPS reception, by utilizing a cost-effective 2D laser scanner and existing 3D surveys, effectively handling complex environmental features.
Implementation Method 1
receiving data obtained from a 2-dimensional, 2D, laser scanner of the transportable apparatus configured to collect information relating to at least a surface
Data Source
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AI summary
A method of localising transportable apparatus (100) within an environment including receiving (402) data obtained from a 2D ranging sensor device (102) of the transportable apparatus configured to collect information relating to at least a surface (120) over which the transportable apparatus is moving in an environment, and using (404) the ranging sensor device data to generate a new 3D point cloud (110) of the environment. The method further obtains (406) data representing an existing 3D point cloud (114) of at least part of the environment, and seeks to match (408) the new 3D point cloud with, or within, the existing 3D point cloud in order to localise the transportable apparatus with respect to the existing point cloud.