On-Board Camera Speed Limit Detection for Multi-Lane Roads
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Solution Overview
Problem
Existing speed limit notification devices for automotive vehicles on multi-lane roads fail to accurately inform drivers of lane-specific speed limits, as they presume a common speed limit for all lanes, leading to insufficient functionality when different speed limits are set for each lane.
Innovation Solution
A navigation system-equipped device using an on-board camera to capture road surface images, a control circuit to specify the speed limit from these images, and a display or speaker to inform the driver, which also checks map data for accuracy and notifies the driver of any discrepancies, allowing for easy detection and display of speed limits for both the own lane and neighboring lanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common speed limit is presumed for all lanes of a multi-lane road, then the device structure can be simplified, but the device fails to function sufficiently when different speed limits are set for each lane
Solution Approach 1:
The device segments the multi-lane road into individual lanes and detects speed limits for each lane separately using multiple detection methods (road surface camera for own lane, map data for all lanes, neighboring lane detection). This segmentation allows the device to handle different speed limits for different lanes while maintaining a relatively simple overall structure.
Solution Approach 2:
The device uses map data as an intermediary to provide speed limit information for lanes where direct detection is not available. The map data serves as a backup and supplementary source, allowing the device to notify drivers of speed limits for all lanes even when the camera can only directly detect the own lane.
2Speed
If the speed limit is read from map data stored in an on-board memory device, then the information can be obtained quickly, but the information may not be updated and may differ from the actual speed limit
Solution Approach 1:
The device implements a feedback mechanism by comparing the speed limit read from map data with the speed limit detected by the road surface camera. When a discrepancy is detected, the system notifies the driver that the map data may be outdated and recommends updating it. This feedback loop ensures the driver is aware of potential inaccuracies in the map data.
Solution Approach 2:
The device performs preliminary detection of speed limits using map data before the vehicle actually reaches the location. This allows the system to have speed limit information ready in advance, providing quick notification to the driver while still allowing for later verification and updates based on actual camera detection.
3Measurement precision
If sophisticated lane detection methods are used to identify the own lane, then accurate speed limit notification can be achieved, but the device complexity increases significantly
Solution Approach 1:
The device uses the fact that the road surface camera is mounted on the own vehicle to automatically identify the own lane - the lane directly beneath the camera is by definition the own lane. This self-service approach eliminates the need for complex lane detection algorithms while still achieving accurate speed limit notification for the own lane.
Solution Approach 2:
The device treats all lanes uniformly by using the same road surface camera to detect speed limits for the own lane and using similar image recognition techniques for neighboring lanes. This homogeneous approach simplifies the system architecture while maintaining accuracy across different lanes.
Data Source
AI summary
A device for informing to a driver a speed limit set for an own lane included in a multi-lane road is installed in a navigation system mounted on an automotive vehicle. The device includes a road surface camera for taking pictures of the speed limit painted on a road surface and informing devices such as a display panel and/or a speaker. The speed limit set for the own lane is specified based on the pictures taken by the road surface camera, and the specified speed limit is informed to the driver. Speed limits set for neighboring lanes may be also specified, and if they are different from the speed limit set for the own lane, this is informed to the driver together with the speed limits set for the neighboring lanes. It is not required to distinguish the own lane from among other lanes included in the multi-lane road because the speed limit set for the own lane is detected by the camera mounted on the own vehicle.