RELATED APPLICATIONS

The present application is the national phase of International Application No. PCT/JP2017/029858, filed on Aug. 22, 2017, which claims priority to and the benefit of Japanese Patent Application No. 2016-162737, filed on Aug. 23, 2016, and the disclosures of which are hereby incorporated herein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a travel track creation device, a travel track creation method, and a travel track creation program for creating a travel track on which a vehicle travels on a road, and a driving assistance device and a driving assistance system.

BACKGROUND ART

A curve of a road such as an expressway or a main highway includes an inlet straight portion that is an inlet of the curve, an inlet clothoid portion continuous to the inlet straight portion, an arc portion continuous to the inlet clothoid portion, an outlet clothoid portion continuous to the arc portion, and an outlet straight portion continuous to the outlet clothoid portion. Such a configuration of the road enables a vehicle to travel smoothly at high speed so that side-slip of the vehicle can be reduced and uncomfort of a passenger can be reduced.

On the other hand, an intersection in an urban distinct, for example, includes only an inlet straight portion, an arc portion continuous to the inlet straight portion, and an outlet straight portion continuous to the arc portion and does not include an inlet clothoid portion and an outlet clothoid portion in some cases.

FIG. 26is a plan view illustrating an example of an intersection. This intersection400is a crossroad where four roads meet. In a case where a vehicle410enters the intersection400along an arrow401from the left in the drawing and travels out of the intersection400along an arrow402upward in the drawing, the vehicle410passes through an inlet straight portion403, an arc portion404continuous to the inlet straight portion403, and an outlet straight portion405continuous to the arc portion404.

As a relevant technique, Patent Document 1 listed below describes a driving assistance system that creates a virtual digital travel track using a line, an arc, a clothoid curve, and so forth based on a road parameter and positional information on a vehicle.

Patent Document 2 listed below describes a road map creation device that detects coordinates of a current location of a mobile object at each predetermined time and, based on a group of detected coordinates, creates a map of roads constituted by straight portions, non-straight portions continuous to the straight portions, and straight portions continuous to the non-straight portions.

CITATION LIST

Patent Documents

PATENT DOCUMENT 1: Japanese Patent No. 4125569

PATENT DOCUMENT 2: Japanese Patent No. 5749359

SUMMARY OF THE INVENTION

Technical Problem

In a case where a road is constituted only by an inlet straight portion, an arc portion continuous to the inlet straight portion, and an outlet straight portion continuous to the arc portion, when a vehicle travels along the road, the vehicle cannot travel smoothly at a connection point between the inlet straight portion and the arc portion and a connection point between the arc portion and the outlet straight portion, resulting in an increased possibility of side-slip of the vehicle and increased uncomfort of a passenger.

In particular, a vehicle equipped with a driving assistance device that assists a steering operation of a driver or performs the steering operation for the driver assists or performs the steering operation so that the vehicle travels along the road, resulting in an increased possibility of side-slip of the vehicle and increased uncomfort of a passenger.

Intersections each constituted only by an inlet straight portion, an arc portion continuous to the inlet straight portion, and an outlet straight portion continuous to the arc portion are present at about 200,000 locations with signals and at about 800,000 locations without signals. Thus, it is highly required to reduce side-slip of vehicles with reduction of uncomfort of passengers.

The present invention has been made in view of the foregoing situations, and has an object of creating a travel track on which a vehicle can travel smoothly.

Solution to the Problem

A travel track creation device according to one aspect of the present invention is a travel track creation device that creates a travel track on which a vehicle travels on a road and which includes an inlet straight portion, an arc portion continuous to the inlet straight portion, and an outlet straight portion continuous to the arc portion, the travel track creation device includes: a travel track creator that creates the travel track including an inlet straight track separated from an outer edge of the inlet straight portion by a predetermined distance toward a center side of the arc portion, an inlet clothoid track continuous to the inlet straight track and formed by connecting a first group of clothoid curves, an arc track continuous to the inlet clothoid track, an outlet clothoid track continuous to the ark track and formed by connecting a second group of clothoid curves, and an outlet straight track continuous to the outlet clothoid track and separated from an outer edge of the outlet straight portion by a predetermined distance toward the center side of the arc portion, wherein the travel track creator includes an arc creator 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 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.

Advantages of the Invention

According to some aspects of the present invention, a travel track on which a vehicle can travel smoothly can be created advantageously.

