Travel trajectory preparation device, method, and program, and drive assist device and system

A driving assistance method for creating a travel track and automatically steering a vehicle that is traveling on a road 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 method comprising:

• a first step of creating 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 arc 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 first step includes
• a second step of creating 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 third step of creating 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;
• and,
• the method further comprising:
• a fourth step of generating a control signal to steer the vehicle according to the travel track;
• and
• a fifth step of applying the control signal to a steering actuator.

A non-transitory computer-readable medium with instructions stored therein, the instructions, when executed by a data processing system, cause the data processing system to perform a travel track creation method for creating a travel track and automatically steering a vehicle that is traveling on a road 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 method comprising:

• a first step of creating 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 arc 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 first step includes
• a second step of creating 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 third step of creating 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;
• and,
• the method further comprising:
• a fourth step of generating a control signal to steer the vehicle according to the travel track;
• and
• a fifth step of applying the control signal to a steering actuator.