Distance Calculation for Curved Road Segments in Autonomous Vehicles

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Solution Overview

Problem

Autonomous vehicles face difficulties in determining the closest distance between a point and a road segment, especially when the road segment includes curves, as existing methods are slow, prone to errors, and inaccurate due to global sampling, derivative-based optimization, and approximation techniques.

Innovation Solution

The technique involves dividing the xy-plane into regions associated with a reference line, using lines normal to the endpoints and a perpendicular bisector to determine the closest point, and applying rules and equations to calculate the minimum distance between points and the reference line, employing algorithms like the Brent Minimization Algorithm.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If global sampling or derivative-based optimization methods are used to determine distance to curved road segments, then measurement coverage is improved, but computational speed deteriorates and accuracy is reduced

Engineering Contradiction:
Improvedistance measurement accuracyVSAvoidcomputational speed
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the space around the curved road segment into multiple regions (first region, second region, third region, fourth region) based on perpendicular lines at endpoints and a perpendicular bisector. Each region has predetermined rules for determining the closest point, avoiding global optimization while ensuring accurate distance measurement for objects in any region.

Inventive Principle:
Principle #1Segmentation

2Productivity

If approximation techniques are used to calculate distance to curved road segments, then computational speed is improved, but measurement precision deteriorates

Engineering Contradiction:
Improvecomputational speedVSAvoiddistance measurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary actions by pre-defining regions and their associated rules before actual distance calculation. The perpendicular lines at endpoints and the perpendicular bisector are established in advance, creating a structured framework that enables rapid determination of the closest point without requiring approximation during runtime.

Inventive Principle:
Principle #10Preliminary action

3Measurement precision

If complex optimization algorithms are used to find the closest point on curved road segments, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvedistance measurement accuracyVSAvoidalgorithm complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the approach from continuous optimization parameters to discrete regional parameters. By defining four distinct regions with specific boundary conditions (perpendicular lines at endpoints, perpendicular bisector), the system transforms a complex continuous optimization problem into a simpler discrete classification problem where the closest point can be determined using predetermined rules for each region.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11661076B1Techniques for determining a distance between a point and a spiral line segment
Publication Date: 2023.05.30 ZOOX INC
  • US11661076B1 patent drawing
  • US11661076B1 patent drawing
  • US11661076B1 patent drawing

AI summary

Techniques and methods for determining a distance between a point within an environment and a reference line are discussed herein. For instance, a vehicle may be navigating. While navigating, the vehicle may receive a reference line that represents a road segment and determine various regions relative to the reference line. Additionally, the vehicle may generate sensor data representing the environment and identify an object using the sensor data. The vehicle may then determine that a location of the object corresponds to a region from the regions. Based on the region, the vehicle may determine a rule for identifying the distance between the vehicle and the reference line. The vehicle may then determine the distance using the rule, the location of the object, and the reference line. Additionally, the vehicle may determine an action for the vehicle to perform that is based on the distance.