Autonomous Vehicle Speed Control for Accurate Roundabout Entry

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Solution Overview

Problem

Existing autonomous vehicle systems using simple definition maps inaccurately locate the beginning of a roundabout, leading to uncomfortable and anxiety-inducing acceleration control due to positioning errors, especially when transitioning onto roundabouts.

Innovation Solution

A method that determines a new starting distance for a roundabout by combining data from a simple definition map, a geolocation system, and an onboard camera, considering the type and position of road signs related to intersections or priority roads, to improve the accuracy of speed regulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If simple definition map data is used to determine roundabout starting distance, then device complexity is reduced, but measurement precision deteriorates due to positioning errors

Engineering Contradiction:
Improvemapping system complexityVSAvoidroundabout start position accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent uses road signs as intermediary objects to bridge the gap between simple definition maps and accurate roundabout positioning. By detecting road signs (yield signs, stop signs, priority road signs) that are reliably positioned relative to roundabout entrances, the system indirectly determines the roundabout start position with high accuracy without requiring complex HD mapping infrastructure.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system leverages existing road infrastructure (road signs) to provide positioning information that would otherwise require complex mapping systems. The road signs themselves serve as the positioning reference, eliminating the need for the vehicle system to carry or process complex mapping data while achieving accurate location determination.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If road sign detection is added to improve positioning accuracy, then measurement precision improves, but device complexity increases due to additional sensors and processing

Engineering Contradiction:
Improveroundabout start position accuracyVSAvoidsensor and processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent makes the existing camera system universal by using it for multiple purposes: general environment perception and specific road sign detection for positioning. The same image processing algorithms and detection mechanisms are leveraged to identify road signs, eliminating the need for dedicated positioning sensors and reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system uses the existing camera and image processing pipeline to create a 'copy' of the road sign detection capability without adding new sensing hardware. The same optical sensors and processing resources that capture general scene information are reused to detect and locate road signs, achieving positioning accuracy without proportional increases in device complexity.

Inventive Principle:
Principle #26Copying

3Ease of operation

If inaccurate roundabout start position is used, then speed regulation simplicity is maintained, but object-affected harmful factors increase due to uncomfortable acceleration control

Engineering Contradiction:
Improvespeed control simplicityVSAvoidpassenger comfort
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary detection of road signs and calculation of accurate roundabout start positions before the vehicle reaches the roundabout. This advance positioning information allows the speed regulation system to plan and execute smooth acceleration and deceleration profiles in advance, avoiding last-minute abrupt control actions that would compromise passenger comfort.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4552938B1Method and device for controlling a speed regulation of an autonomous vehicle
Publication Date: 2026.03.04 STELLANTIS AUTO SAS
  • EP4552938B1 patent drawingFigure 1
  • EP4552938B1 patent drawingFigure 2
  • EP4552938B1 patent drawingFigure 3

AI summary

Method for controlling the speed regulation of an autonomous vehicle to manage the acceleration of said vehicle approaching a roundabout, said method being implemented by a processor and comprising the steps of: • Determining, from data from a simple definition map and a geolocation system, ∘ a first distance (400), relative to said vehicle, from the start of said roundabout; ∘ a first type (410) of a first road sign; and ∘ a second distance (420), relative to said vehicle, from said first road sign when said first type relates to an intersection or a priority road; • Determining a new distance (450) from the start of said roundabout based on said first distance, on said first type and on said second distance; • Regulating (460) the speed of the vehicle from said new distance from the start of the roundabout.