Vehicle Speed Estimation Using Single Lidar Scan Alignment
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Solution Overview
Problem
Existing methods for estimating the speed of vehicles using lidar sensors require multiple acquisitions and complex data fusion, which can be inefficient and prone to errors.
Innovation Solution
A method utilizing a single acquisition from a scanning lidar sensor that aligns point cloud data in a reference direction to calculate relative speed between the ego-vehicle and objects, allowing for speed estimation based on a single scan by correcting positions and using time stamps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple acquisitions and complex data fusion are used to estimate vehicle speed, then measurement precision is improved, but device complexity and processing time increase
Solution Approach 1:
The patent extracts and utilizes only the essential information needed for speed estimation from the point cloud data - specifically the position of points at different time stamps along the scanning path. By focusing only on the displacement of specific points rather than fusing complex multi-sensor data, the method achieves speed estimation without requiring complex data fusion systems.
Solution Approach 2:
The patent applies preliminary geometric correction to align points corresponding to the same azimuth or elevation value along a reference direction before speed calculation. This preliminary alignment simplifies subsequent speed computation by ensuring that point displacements directly reflect actual object movement rather than scanning artifacts, eliminating the need for complex post-processing fusion.
2Measurement precision
If multiple acquisitions are used for speed estimation, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent computes speed from point cloud data acquired continuously during a single scanning operation, utilizing the temporal progression of points within one acquisition. By processing points as they are acquired during the scan rather than waiting for multiple complete acquisitions, the method maintains continuous useful action and reduces time loss while preserving measurement precision through the use of time-stamped position data.
3Productivity
If a single acquisition is used for speed estimation, then productivity is improved, but measurement precision deteriorates
Solution Approach 1:
The patent transitions from analyzing only spatial coordinates to incorporating the temporal dimension by utilizing time stamps associated with each point in the point cloud. This dimensional addition allows speed calculation from a single acquisition by measuring displacement over time, achieving both high productivity and measurement precision without requiring multiple acquisitions.
Solution Approach 2:
The patent changes the approach from using multiple acquisitions to utilizing temporal parameter variations within a single acquisition. By focusing on the time stamp parameter and computing displacement between points at different times within one scan, the method achieves accurate speed estimation while maintaining high processing efficiency.
Data Source
AI summary
A method for estimating the speed of a vehicle, including a scanning lidar sensor acquiring a point cloud, each point associated with an initial three-dimensional position, a time stamp, and an azimuth and elevation orientation of the line of sight of the lidar sensor. The computer processing the point cloud, including: detecting at least one object represented by a subset of points of the point cloud; determining a corrected position of a plurality of points of the object corresponding to the same azimuth or elevation value of the line of sight of the lidar sensor, the corrected positions of the plurality of points being aligned in a reference direction; and determining a relative speed between the ego-vehicle and the object, based on a difference between a corrected position and an initial position of at least one point of the object, and based on the time stamp associated with the point.