Clothoid Travel Track Creation for Intersection Stability
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Solution Overview
Problem
Vehicles traveling through intersections with only inlet and outlet straight portions and arc portions experience increased side-slip and passenger discomfort due to abrupt changes in curvature, which existing driving assistance systems struggle to mitigate effectively.
Innovation Solution
A travel track creation device that includes an inlet straight track, an inlet clothoid track, an arc track, an outlet clothoid track, and an outlet straight track, where the clothoid tracks are formed by connecting clothoid curves to smooth the vehicle's transition through these sections, reducing lateral acceleration and jerk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a road is constituted only by an inlet straight portion, an arc portion, and an outlet straight portion, then the road structure is simple, but the vehicle cannot travel smoothly at connection points resulting in increased side-slip and passenger discomfort
Solution Approach 1:
The invention divides the road into six distinct segments: inlet straight portion, inlet clothoid portion, arc portion, outlet clothoid portion, outlet straight portion, and connection portions. By segmenting the road structure and introducing clothoid portions at connection points, the patent resolves the contradiction between structural simplicity and travel stability, as each segment serves a specific function in ensuring smooth vehicle transition.
Solution Approach 2:
The clothoid portion acts as an intermediary element between the straight portion and the arc portion. This intermediate curve with gradually changing curvature radius mitigates the abrupt transition that would otherwise occur, thereby reducing side-slip and passenger discomfort while maintaining overall structural efficiency.
2Ease of operation
If driving assistance devices assist steering operations to make vehicles travel along the road, then the vehicle follows the road trajectory accurately, but the possibility of side-slip increases and passenger comfort deteriorates due to abrupt curvature changes
Solution Approach 1:
The invention applies curved geometry, specifically clothoid curves, at the connection points between straight and arc portions. This curvature design ensures that the steering angle changes gradually rather than abruptly, allowing driving assistance devices to maintain accurate trajectory control while minimizing lateral acceleration shocks that cause side-slip and discomfort.
3Reliability
If clothoid portions are added to intersections to enable smooth travel, then vehicle stability improves, but the road structure and travel track creation complexity increases
Solution Approach 1:
The invention changes the curvature radius parameter along the travel track, specifically using clothoid curves where the curvature radius varies continuously from the straight portion to the arc portion. This parameter variation enables smooth transitions and improved vehicle stability, while the systematic approach to implementing these changes across standard road segments helps manage the complexity of travel track creation.
Data Source
AI summary
A travel track creation device (2) includes a travel track creator (42) that creates a travel track including an inlet straight track, an inlet clothoid track formed by connecting a first group of clothoid curves, an arc track, an outlet clothoid track formed by connecting a second group of clothoid curves, and an outlet straight track, wherein the travel track creator (42) includes an arc creator (42a) that creates the arc track which is located further on a side opposite to the center side of the arc portion than a passing target point and a radius of which is as large as possible, the passing target point being separated from an inner edge of the arc portion by a predetermined distance toward the side opposite to the center side of the arc portion, and a clothoid creator (42b) that creates the inlet clothoid track in which a radius of a last tangential arc corresponds to a radius of the arc track and a start point of which is in contact with the inlet straight track and in which a direction angle of the start point corresponds to a direction angle of the inlet straight track, and the outlet clothoid track in which a radius of a last tangential arc corresponds to a radius of the arc track and which is in contact with the outlet straight track and in which a direction angle of a start point corresponds to a direction angle of the outlet straight track.