Vehicle Speed Limit Control System Using Time-Based Estimation
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Solution Overview
Problem
Existing vehicle control systems fail to accurately recognize speed limit values when image capturing conditions are inadequate, leading to potential speed limit violations by using outdated or incorrect speed limit values.
Innovation Solution
A control system that includes an imaging unit, recognition unit, measurement unit, estimation unit, display unit, and command determination unit to measure elapsed time or travel distance since the last recognized speed limit, estimate the current speed limit, and allow the driver to switch to the estimated value if necessary, ensuring the vehicle is not speed-limited by an outdated value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the control system uses image recognition to identify speed limit values, then the speed limit value can be accurately obtained from road signs, but the system may fail to recognize the speed limit value when capturing conditions are inadequate
Solution Approach 1:
The system performs preliminary actions by measuring elapsed time and travel distance continuously before recognition failure occurs. When inadequate capturing conditions are detected, the system has already accumulated time and distance data, enabling it to switch to alternative estimation methods based on navigation information, thereby maintaining reliability while preserving the accuracy of image recognition when conditions are good.
Solution Approach 2:
The system introduces an intermediary mechanism that combines image recognition results with navigation device information. The control unit acts as an intermediary that switches between the recognition unit (for accurate values when visible) and the navigation unit (for fallback estimation), resolving the contradiction by using each source according to its strengths and weaknesses.
2Reliability
If the system switches to estimated speed limit value from navigation device when recognition fails, then the vehicle can maintain speed limitation functionality, but the estimated value may differ from the actual speed limit value on the road
Solution Approach 1:
The system implements feedback by continuously monitoring both the recognition unit output and the estimation unit output. When image recognition succeeds, the system uses that accurate value and can verify it against navigation data. When recognition fails, the system switches to navigation-based estimation, creating a feedback loop that maintains functional reliability while being aware of the reduced precision in fallback mode.
Solution Approach 2:
The system changes the information source parameter dynamically - switching between image-based recognition (high precision, conditional reliability) and navigation-based estimation (lower precision, continuous availability). This parameter change allows the system to maintain the speed limitation function under all conditions while accepting variable precision based on environmental factors.
3Duration of action of stationary object
If the system continues using a previously recognized speed limit value when capturing conditions are repeatedly inadequate, then the speed limitation function remains active, but the speed limit value may be outdated and different from the actual value
Solution Approach 1:
The system applies dynamics by making the speed limit value source adaptive rather than static. The control unit dynamically switches between using the recognition unit output and the navigation unit output based on real-time capturing conditions. This dynamic approach maintains the duration of the speed limitation function while ensuring the validity of the speed limit value through continuous adaptation to changing environmental conditions.
Solution Approach 2:
The system performs preliminary monitoring of capturing conditions and continuously updates elapsed time and travel distance measurements. When inadequate conditions are detected before complete recognition failure, the system can proactively switch to navigation-based estimation, preventing the use of outdated values and maintaining both function duration and value validity.
Data Source
AI summary
A control system for a vehicle includes an imaging device; a co-ECU to limit the travel speed of the vehicle; and an ECU to set the speed limit, that recognizes the speed limit value on a road while traveling, and sets the recognized speed limit value in the co-ECU. If the elapsed time since the speed limit value has been set reaches a predetermined time, the ECU estimates the speed limit value on the road while traveling, and if receiving a switch command, switches the speed limit value set in the co-ECU to the estimated speed limit value so as to avoid limiting the vehicle speed by a speed limit value that is different from the actual speed limit value on the road.