Pedestrian Motion Prediction Grids for Autonomous Vehicle Path Planning

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Solution Overview

Problem

Autonomous vehicles face challenges in predicting the motion of diverse and unpredictable pedestrians, such as those who are partially occluded, change direction quickly, and traverse various terrains, due to suboptimal data quality and complexity in trajectory modeling.

Innovation Solution

A grid-based prediction method is employed, where a grid is projected around detected pedestrians to predict their possible future locations within a short time frame, using observed speed, direction, and orientation, with high-probability cells forming a heat map that helps in path planning and contour generation to avoid potential areas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If learned trajectory proposal based behavior models are used to predict pedestrian motion, then prediction accuracy can be improved when data quality is high, but the system becomes overly complex and computationally intensive when dealing with diverse and unpredictable pedestrian behaviors

Engineering Contradiction:
Improveprediction accuracyVSAvoidtrajectory modeling complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the continuous trajectory prediction problem into discrete grid cells around the pedestrian. Instead of modeling continuous trajectories, the system divides space into a grid and predicts the probability of the pedestrian entering each cell within a time window. This segmentation simplifies the computational complexity while maintaining prediction accuracy for diverse pedestrian behaviors.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a computationally inexpensive grid-based probability map that is regenerated frequently (short-lived) rather than relying on complex, pre-trained trajectory models. Each grid cell stores a simple probability value that is quickly updated based on current pedestrian state, avoiding the need for extensive training data and complex model architectures.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If extensive training data is collected to improve pedestrian behavior prediction, then model accuracy improves, but data collection time and processing complexity increase significantly

Engineering Contradiction:
Improveprediction accuracyVSAvoiddata collection and processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system uses the pedestrian's own observed motion data (speed, direction, orientation) to generate predictions in real-time, rather than relying on pre-collected training data from extensive datasets. The grid-based probability calculation is performed autonomously using current sensor data, eliminating the need for separate data collection and training phases.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent pre-defines the grid structure and probability calculation methodology before operation, so that during runtime, only simple probability computations are needed based on current pedestrian state. This preliminary setup avoids the need for time-consuming data collection and model training during deployment.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the vehicle maintains a larger safety distance from pedestrians to avoid collisions, then collision risk decreases, but the vehicle's mobility and efficiency are reduced

Engineering Contradiction:
Improvecollision avoidanceVSAvoidvehicle mobility
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies different safety considerations to different spatial locations by computing cell-by-cell probability maps around each pedestrian. The vehicle can maintain larger distances in high-probability cells (where collision risk is high) while allowing closer proximity in low-probability cells, optimizing the balance between safety and mobility dynamically based on local risk assessment.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The safety margin is not fixed but dynamically adjusted based on real-time probability predictions. The vehicle continuously updates the grid-based probability map and adjusts its path planning accordingly, allowing it to take calculated risks in low-risk areas while maintaining conservative distances in high-risk areas, thereby improving overall mobility without compromising safety.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS11783614B2Pedestrian behavior predictions for autonomous vehicles
Publication Date: 2023.10.10 WAYMO LLC
  • US11783614B2 patent drawing
  • US11783614B2 patent drawing
  • US11783614B2 patent drawing

AI summary

The technology relates to controlling a vehicle in an autonomous driving mode. For instance, sensor data identifying an object in an environment of the vehicle may be received. A grid including a plurality of cells may be projected around the object. For each given one of the plurality of cells, a likelihood that the object will enter the given one within a period of time into the future is predicted. A contour is generated based on the predicted likelihoods. The vehicle is then controlled in the autonomous driving mode in order to avoid an area within the contour.