Trailer Angle Measurement Using Adaptive Lidar Switching
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Solution Overview
Problem
Current methods for trailer angle measurement in semi-trailers face challenges such as limited detection range, insufficient generalization, and accuracy issues, particularly in autonomous reversing scenarios, due to the use of single lidar systems which are not suitable for irregular tractor-trailer movements and require complex preparation.
Innovation Solution
The implementation of a method and apparatus using a single-beam lidar at the rear of the tractor and multiple-beam lidars on both sides, with a laser reflection plate at the trailer head, allowing for the determination of whether to use single-beam or multiple-beam lidar based on the initial trailer angle, and applying coordinate transformations to form a candidate point cloud for accurate boundary line determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lidar system is used for trailer angle measurement, then the device complexity is reduced, but the measurement precision and detection range are insufficient
Solution Approach 1:
The system divides the lidar measurement function into two segments: single-beam lidar for obtaining initial trailer angle and multiple-beam lidar for precise boundary line detection. This segmentation allows each subsystem to be optimized for its specific function, resolving the contradiction between simple structure and high precision measurement.
Solution Approach 2:
The system dynamically switches between single-beam and multiple-beam lidar based on the initial trailer angle. When the angle is small, single-beam lidar is used; when the angle is large, multiple-beam lidar is activated. This dynamic adaptation ensures measurement precision across the full detection range while maintaining structural simplicity.
2Adaptability or versatility
If multiple-beam lidar is used for full-angle detection, then the detection range is improved, but the device complexity increases
Solution Approach 1:
The system implements dynamic configuration where multiple-beam lidar is only activated when needed (when initial trailer angle indicates large deflection). This dynamic approach provides full-angle detection capability while avoiding the complexity of permanently deploying multiple lidars in all operating conditions.
Solution Approach 2:
The multiple-beam lidar system is designed to handle multiple detection scenarios (small angles, large angles, irregular movements) with a single unified apparatus. This multi-functionality achieves comprehensive detection range without requiring separate specialized systems for each scenario.
3Measurement precision
If complex preparation and processing are applied to lidar data, then the measurement precision is improved, but the processing time increases
Solution Approach 1:
The system performs preliminary coordinate transformation and point cloud filtering before boundary line determination. By preprocessing the data in advance and organizing it into candidate point clouds, the subsequent optimization process works with pre-organized data, reducing overall processing time while maintaining precision.
Solution Approach 2:
The system replaces complex iterative boundary detection algorithms with an optimized objective function that directly computes the boundary line from preprocessed point clouds. This substitution of computational mechanics reduces processing time while preserving measurement precision.
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 approach enables fast and accurate trailer angle measurement with a simple structure, achieving full-angle detection and maintaining high accuracy in various scenarios, with an error of within 0.3° and fluctuation of ±0.25°, and supports real-time detection at a frequency of up to 20 Hz.
Implementation Method 1
A single-beam lidar is provided at a rear part of the tractor, at least one multiple-beam lidar is provided on both sides of the tractor
Implementation Method 2
collecting laser light emitted by the multiple-beam lidar on a side of the deflection direction and reflected by a surface of the trailer
Data Source
AI summary
The present disclosure relates to autonomous vehicle technology, and provides a method and an apparatus for trailer angle measurement, as well as a vehicle. With the present disclosure, it can be determined whether to use a single-beam lidar or a multiple-beam lidar for trailer angle measurement based on an initial trailer angle. When it is determined to use the multiple-beam lidar a deflection direction of the semi-trailer can be obtained, and laser light emitted by the multiple-beam lidar on a side of the deflection direction and reflected by a trailer surface can be collected. A coordinate transformation and selection process can be applied on the laser point cloud to form a candidate point cloud. A boundary straight line of the trailer can be determined by means of optimized solution of the candidate point cloud. A trailer angle can be determined based on the boundary straight line of the trailer.