Roundabout Exit Speed Control Using Route-Based Acceleration Timing
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Solution Overview
Problem
Existing vehicle control systems inaccurately determine exit from a roundabout, leading to unnecessary acceleration and potential speed limit violations.
Innovation Solution
A vehicle control device that acquires the traveling route and speed limits of a roundabout and connected roads, calculates a target vehicle speed and necessary acceleration period/distance, and initiates acceleration control based on predetermined conditions to ensure compliance with speed limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exit determination is based on traveling dynamics quantity (yaw rate or steering angle), then the system can detect exit motion, but it may erroneously determine exit when the vehicle changes lanes, causing unnecessary acceleration
Solution Approach 1:
The exit determination process is segmented into multiple independent checks: (1) acquiring the planned traveling route from navigation device, (2) identifying whether the route includes a roundabout with exit road, (3) determining current position on the circular road, and (4) calculating distance to exit. This multi-stage segmentation replaces the single unreliable dynamics-based detection, ensuring each stage validates the exit condition independently to prevent false positives during lane changes.
Solution Approach 2:
The traveling route information from the navigation device serves as an intermediary reference that mediates between the vehicle's actual motion and the exit determination logic. By comparing the vehicle's current position and motion against the pre-acquired route data (which includes the circular road and exit road identification), the system achieves accurate exit detection without relying solely on dynamics quantities that can be ambiguous during normal maneuvers like lane changes.
2Device complexity
If target vehicle speed from ACC is used as acceleration target, then the system can maintain simple control logic, but the vehicle may accelerate exceeding the speed limit in the roundabout when exit is erroneously determined early
Solution Approach 1:
The system performs preliminary acquisition of speed limit information for both the circular road and the exit road before initiating acceleration control. By pre-obtaining these speed limits and storing them for comparison, the system ensures that when acceleration is commanded, the target speed is calculated based on the appropriate speed limit (circular road limit while in the roundabout, exit road limit after exiting). This preliminary preparation prevents speed limit violations without adding complex real-time decision logic during acceleration.
3Productivity
If acceleration control starts immediately when exit is detected, then the vehicle can reach optimal speed quickly, but it may cause unnecessary acceleration when exit determination is erroneous
Solution Approach 1:
The system calculates the distance to the exit road and the required acceleration period in advance, before initiating acceleration control. By pre-determining these parameters based on the acquired traveling route and current position, the system can then start acceleration at the optimal moment with confidence that the exit is genuine. This preliminary calculation of acceleration parameters (distance and time) ensures rapid response when needed while preventing premature acceleration triggered by false exit detection.
Data Source
AI summary
A vehicle control device that controls traveling of a vehicle at a roundabout in which a plurality of connected roads is connected to a circular road, acquires a traveling route of the vehicle including an exit road that is a connected road to which the vehicle is to exit from the circular road, acquires speed limits of the circular road and the exit road, calculates a target vehicle speed when the vehicle exits to the exit road from the circular road based on the speed limits, calculates an acceleration necessary period or an acceleration necessary distance necessary for accelerating the vehicle to the target vehicle speed based on current vehicle speed of the vehicle traveling on the circular road and the target vehicle speed, and starts acceleration control of accelerating the vehicle at predetermined acceleration when the calculated acceleration necessary period or acceleration necessary distance satisfies a predetermined start condition.