INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-237486 filed on Dec. 19, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to an automatic driving system that controls automatic driving of a vehicle.

2. Description of Related Art

International Publication No. WO 2017/141426 discloses a vehicle control device that controls automatic driving of a vehicle. The vehicle control device ends the automatic driving at a predetermined scheduled end point. When the position of the vehicle reaches a predetermined distance before the scheduled end point, the vehicle control device starts a deceleration control for decelerating the vehicle. A purpose of the deceleration control is to prompt a driver of the vehicle to transition to manual driving. The vehicle control device sets a transition completion point where the deceleration control is ended, to a point in front of the scheduled end point. Then, the vehicle control device performs the deceleration control, such that the vehicle stops at the transition completion point, that is, such that vehicle velocity becomes zero at the transition completion point.

Japanese Patent Application Publication No. 2017-159885 discloses a driving alternation control device. The alternation execution zone is a zone in which the driver starts to perform driving operations instead of an automatic driving function. For reducing a driving load on the driver in the alternation execution zone, the driving alternation control device changes a traveling control parameter in a switching zone in front of the alternation execution zone, such that the driving load decreases.

Japanese Patent Application Publication No. 2018-134971 discloses a vehicle control device that controls the automatic driving of the vehicle. The vehicle control device causes the driver to take over at least a part of the automatic driving and perform manual driving. In advance, the vehicle control device gives a taking-over demand to the driver. The vehicle control device sets the timing to give the taking-over demand, based on a driving difficulty level after the taking-over.

SUMMARY

An automatic driving system controls the automatic driving of the vehicle. Suppose that the automatic driving system ends at least a part of the automatic driving. The driver of the vehicle takes over at least a part of the driving of the vehicle, from the automatic driving system. On this occasion, the driver is likely to take over the driving while recognizing the external environment of the vehicle. Accordingly, if the vehicle velocity when the driver takes over the driving is set in the same way regardless of the external environment, there is concern that the driver has a strange feeling.

An object of the present disclosure is to provide a technology that makes it possible to reduce the strange feeling of the driver when the driver takes over at least a part of the driving of the vehicle from the automatic driving system.

An aspect of the present disclosure relates to an automatic driving system. The automatic driving system includes a control device that controls automatic driving of a vehicle, and a storage device that contains external environment information indicating an external environment of the vehicle. A driving transition zone is a zone in which a driver of the vehicle takes over at least a part of driving of the vehicle, from the control device. A termination target velocity is a target velocity of the vehicle at an end point of the driving transition zone. The control device variably sets the termination target velocity, depending on the external environment at the end point or the external environment surrounding the end point, and controls the velocity of the vehicle in the driving transition zone, such that the velocity of the vehicle at the end point is the termination target velocity.

The automatic driving system according to the present disclosure variably sets the termination target velocity at the end point, depending on the external environment at the end point of the driving transition zone or the external environment surrounding the end point. Then, the automatic driving system executes the velocity control such that the velocity of the vehicle at the end point is the set termination target velocity. This reduces the strange feeling of the driver when the driver takes over the driving of the vehicle from the automatic driving system.

