LiDAR Localization Using RNN for Temporal Smoothness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LiDAR localization methods for autonomous vehicles require substantial engineering efforts and are scenario-dependent, lacking in effectively addressing 3D geometry-related tasks, particularly in achieving centimeter-level accuracy and sub-degree orientation estimation.
Innovation Solution
A learning-based LiDAR localization system using convolutional neural networks (CNNs) and recurrent neural networks (RNNs) to create a probability offset volume representing the matching cost between online LiDAR frames and a pre-built point cloud map, generating a trajectory of localization results through recurrent neural networks, thereby achieving temporal smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing LiDAR localization approaches are used, then localization accuracy and robustness are improved, but engineering efforts and system complexity increase substantially
Solution Approach 1:
The patent replaces traditional handcrafted localization pipelines with a neural network-based system. Specifically, it uses a U-Net architecture for cost volume processing and RNNs for temporal smoothing, substituting manual feature engineering and geometric algorithms with learned representations that automatically adapt to different scenarios without requiring substantial engineering tuning.
Solution Approach 2:
The patent transforms the localization problem into a parameter estimation task where the neural network learns optimal parameters (localization offsets) from training data. By changing from fixed handcrafted parameters to learned parameters, the system achieves high accuracy across diverse scenarios while reducing the need for scenario-specific engineering adjustments.
2Measurement precision
If handcrafted localization pipelines are used, then localization accuracy is improved, but adaptability to different scenarios decreases
Solution Approach 1:
The patent replaces scenario-specific handcrafted pipelines with a universal neural network system. The U-Net and RNN architecture learns generalizable features from training data across multiple scenarios, enabling the same system to adapt to different environments (urban, rural, daytime, nighttime) without requiring scenario-specific tuning or multiple specialized pipelines.
Solution Approach 2:
The patent performs preliminary learning during a training phase where the neural network processes labeled data from various scenarios. This preliminary action allows the system to pre-learn scenario-invariant features and adaptations, so that during actual operation, the same trained model can generalize to new scenarios without requiring additional scenario-specific engineering work.
3Reliability
If neural networks are used for semantics processing, then processing quality is improved, but effectiveness in 3D geometry tasks decreases
Solution Approach 1:
The patent merges semantics processing and 3D geometry localization into a unified neural network framework. The U-Net processes the cost volume (which encodes both semantic and geometric information) and the RNN processes temporal sequences, combining the strengths of neural networks in both semantic understanding and geometric parameter estimation within a single end-to-end trainable system.
Solution Approach 2:
The patent creates a composite neural network architecture that combines different network types (U-Net for spatial processing, RNN for temporal processing) to handle both semantic and geometric aspects of localization. This composite structure leverages the complementary strengths of each network type, with U-Net excelling at spatial feature extraction and RNN at temporal smoothness, achieving superior performance in both semantics and 3D geometry tasks.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A method for temporal smoothness in localization results for an autonomous driving vehicle includes creating a probability offset volume that represents an overall matching cost between a first set of keypoints from the online point cloud and a second set of keypoints from a pre-built point cloud map for each of a series of sequential light detection and ranging (LiDAR) frames in an online point cloud (1301). The method further includes compressing the probability offset volume into multiple probability vectors across a X dimension, a Y dimension and a yaw dimension (1303); providing each probability vector of the probability offset volume to a number of recurrent neural networks (RNNs) (1305); and generating, by the RNNs, a trajectory of location results across the plurality of sequential LiDAR frames (1307).