Ramp Lane Exit Detection Using Traffic Sign Speed Patterns
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Solution Overview
Problem
Conventional driving assistance devices struggle to detect the exit of a ramp lane connected to a highway without navigation information, making it difficult for drivers to accurately determine when they have left the highway.
Innovation Solution
A driving assistance device equipped with a traffic sign detection system using an in-vehicle camera to identify traffic signs, including ramp signs with speed limit symbols, which detects entry into a ramp lane by recognizing specific speed reduction patterns and notifies the driver through a display unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If navigation information is used to detect ramp lane exit, then detection accuracy is improved, but device complexity and cost increase due to requiring navigation systems
Solution Approach 1:
The invention extracts the essential detection function from the navigation system by using only the camera to capture traffic signs. The judgment section analyzes traffic sign images to detect ramp lane exit without requiring the complex navigation information processing system, thereby reducing device complexity while maintaining detection accuracy.
Solution Approach 2:
Instead of relying on navigation information, the system creates a visual copy of traffic signs through the camera and analyzes their characteristics (such as speed limit symbols and arrangement patterns) to determine ramp lane exit. This copying approach replaces the need for navigation system data while achieving the same detection goal.
2Reliability
If navigation system is required for ramp lane detection, then detection reliability is improved, but ease of operation deteriorates due to limited applicability
Solution Approach 1:
The invention makes the ramp lane detection function universal by using a camera that can be mounted on any vehicle, rather than requiring a navigation system. The traffic sign detection and analysis capability works across different vehicle types and configurations, significantly improving ease of operation and system applicability while maintaining reliable detection through image-based judgment.
3Device complexity
If traffic sign detection is used instead of navigation information, then device complexity is reduced, but measurement precision may deteriorate
Solution Approach 1:
The judgment section focuses on detecting specific local characteristics of traffic signs (such as speed limit symbols and their arrangement patterns) rather than requiring overall navigation information. By concentrating on these key local features, the system achieves accurate ramp lane exit detection with a simpler camera-based approach, resolving the contradiction between device complexity and measurement precision.
Data Source
AI summary
An ECU as a driving assistance device has a traffic sign detection section, a lane entry detection section and a judgment section. The traffic sign detection section detects traffic signs including a speed limit symbol based on front-image data captured by an in-vehicle camera. The lane entry detection section detects that the own vehicle has entered a ramp lane to leave a highway. The judgment section detects an extent of a current driving lane as the ramp lane when following conditions (c1) and (c2) are satisfied after the lane entry detection section detects the entry of the own vehicle into the ramp lane: (c1) not less than two traffic signs are arranged along the current driving lane in forward direction of the vehicle; and (c2) an arrangement of speed limit symbols included in the detected traffic signs satisfy a predetermined speed reduction pattern.