Vehicle Speed Limit Display Using Distance-Gated Sign Detection
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Solution Overview
Problem
Existing speed limit display devices for vehicles often incorrectly display speed limits from adjacent roads, leading to the display of irrelevant or incorrect speed limits, which can confuse drivers and increase the likelihood of non-applicable speed limits being shown.
Innovation Solution
A speed limit display device equipped with a camera and processing unit that captures images of the landscape in front of the vehicle, detects traffic signs, and only displays the speed limit if the sign is within a predetermined distance, using a distance-based condition to determine relevance and adjusting this distance based on the detected speed limit's value to accurately display applicable speed limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the camera captures traffic signs in the landscape without distance verification, then the device can detect more speed limit signs, but it increases the likelihood of displaying incorrect speed limits from adjacent roads
Solution Approach 1:
The patent introduces an intermediary element (a sign-mounted illumination device with a specific symbol) that acts as a mediator between the traffic sign and the detection system. This illumination device is captured by the camera along with the traffic sign, and its presence serves as verification that the detected speed limit sign is relevant to the vehicle's current road, thereby resolving the contradiction between detecting more signs and ensuring correctness
Solution Approach 2:
The patent replaces the traditional mechanical/physical verification method (manual checking of sign relevance) with an optical detection system. The camera captures both the traffic sign and the associated illumination device, and the processing unit automatically verifies the relationship between them through image analysis, substituting human judgment with automated optical-mechanical detection
2Reliability
If the predetermined distance threshold is set to filter out distant signs, then the device reduces false positives from adjacent roads, but it may miss relevant signs on wider roads
Solution Approach 1:
The patent makes the distance threshold dynamic rather than fixed. The processing unit adjusts the predetermined distance based on detected road width characteristics - allowing larger thresholds for wider roads (like expressways) and smaller thresholds for narrower roads. This dynamic adjustment resolves the contradiction by adapting the filtering criterion to different road types, maintaining reliability while preserving versatility
Solution Approach 2:
The patent changes the parameter of distance threshold based on road characteristics. By analyzing the captured image to determine road width and adjusting the distance parameter accordingly, the system maintains high reliability across different road types. This parameter adaptation allows the system to handle both narrow local roads and wide expressways effectively
Data Source
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AI summary
A speed limit display device (10) for a vehicle, includes an indicator (13) configured to display information related to a speed limit of a road; an image obtaining device (11) configured to capture an image of a landscape and obtain image data of the landscape; and a processing portion (12) configured to detect the speed limit indicated on a traffic sign in the captured landscape, and display the speed limit on the indicator. The processing portion is configured to i) determine whether a predetermined condition is satisfied when the traffic sign is detected, the predetermined condition including a condition that a distance between the vehicle and the traffic sign be less than a predetermined distance, ii) display the detected speed limit when the predetermined condition is satisfied, and iii) not display the detected speed limit when the predetermined condition is not satisfied.