68 of the monitor device 32, the control device 34, and the like.

Note that the hardware configuration of the parking assist system 20 is not limited to that described above, and should be appropriately designed in accordance with a form of the vehicle 10 and the like. For example, in FIG. 2, a configuration is exemplified in which one control device 34 executes various processes for realizing various functions of the vehicle 10, but a plurality of control devices may be configured to realize various functions by performing processing in cooperation.

FIG. 3 is a block diagram illustrating an example of a functional configuration of the parking assist system 20 according to the embodiment. The parking assist system 20 according to the present embodiment includes an obstacle detection unit 101, a parking-slot-entry path generation unit 102, a turning path generation unit 103, and a traveling control unit 104. These functional components 101 to 104 can be configured by cooperation of, for example, pieces of hardware as illustrated in FIG. 2 and software (such as a program for controlling the CPU 34a) for controlling these pieces of hardware.

The obstacle detection unit 101 acquires obstacle information regarding an obstacle present around the vehicle 10. The obstacle detection unit 101 generates obstacle information regarding an obstacle such as another vehicle present around the vehicle 10, on the basis of distance information (for example, time of flight (TOF)), relative speed information (for example, a Doppler frequency), and the like acquired by the ultrasonic sensor 16, for example. The obstacle information may include, for example, a distance from the vehicle 10 to the obstacle, a shape of the obstacle, a relative speed between the vehicle 10 and the obstacle, and the like. The obstacle detection unit 101 updates the obstacle information in accordance with movement of the vehicle 10. The obstacle information may be updated at a predetermined time period.

The parking-slot-entry path generation unit 102 sets a target position in a parking area on the basis of the obstacle information, and generate a parking-slot-entry path for guiding the vehicle 10 to the target position. The parking-slot-entry path generation unit 102 updates the target position and the parking-slot-entry path in accordance with update of the obstacle information.

The turning path generation unit 103 generates a turning path for guiding the vehicle 10 in a direction away from the parking area on the basis of the obstacle information. The turning path generation unit 103 according to the present embodiment generates the turning path when a predicted arrival position of the vehicle 10 present on the parking-slot-entry path corresponding to the target position before update is closer to an obstacle than the target position after update.

The traveling control unit 104 performs a process for causing the vehicle 10 to travel on the basis of the parking-slot-entry path in a case where no turning path is generated, and performs a process for causing the vehicle 10 to travel on the basis of the turning path in a case where the turning path is generated. The “process for causing the vehicle 10 to travel” herein may be, for example, both automatic steering control and automatic acceleration/deceleration control, or only the automatic steering control. The traveling control unit 104 according to the present embodiment outputs a control signal to at least one of the braking mechanism 22, the driving mechanism 24, the steering mechanism 26, or the shifting mechanism 28.

FIG. 4 is a view illustrating an example of a parking-slot-entry path Re. As illustrated in FIG. 4, the parking-slot-entry path Re is a path for guiding the vehicle 10 from a current position Pc (here, a central portion of a line connecting rear wheels) to a target position Pt set in a parking area A.

FIG. 5 is a view illustrating an example of a turning path Rs. As illustrated in FIG. 5, the turning path Rs is a path for guiding the vehicle 10 from the current position Pc in a direction away from the parking area A (the target position Pt).

In the example illustrated in FIGS. 4 and 5, a shape of another vehicle 70 as an example of the obstacle is estimated on the basis of detection results of the ultrasonic sensors 16a and 16b installed on a left side surface of the vehicle 10, and the target position Pt (the parking area A) is set on the basis of the estimation result. At this time, since detection accuracy of the ultrasonic sensors 16a and 16b decreases as the distance increases, it is difficult to estimate a shape of a rear portion of the another vehicle 70. Therefore, the shape of the another vehicle 70 is usually assumed to be extending perpendicularly to a front-rear direction of the vehicle 10.

Here, in the example illustrated in FIG. 4, an angle formed by an own-vehicle direction D1 which is the front-rear direction of the vehicle 10 before a start of the parking operation and an another-vehicle direction D2 which is a front-rear direction of the another vehicle 70 is a substantially right angle. In such a case, even if the ultrasonic sensors 16a and 16b cannot acquire information regarding the shape of the rear portion of the another vehicle 70, the shape of the another vehicle 70 can be estimated relatively accurately, and the target position Pt can be appropriately set.

However, when the angle formed by the own-vehicle direction D1 and the another-vehicle direction D2 is not a right angle, the shape of the another vehicle 70 cannot be accurately estimated, and the target position Pt may not be appropriately set. Such a problem will be described below with reference to FIGS. 6 and 7.

FIG. 6 is a view illustrating an example of the target position Pt set when the angle formed by the own-vehicle direction D1 and the another-vehicle direction D2 is not a right angle. FIG. 7 is a view illustrating an example of an estimated shape 70′ of the another vehicle 70 when the angle formed by the own-vehicle direction D1 and the another-vehicle direction D2 is not a right angle.

In the parking area A, a longitudinal direction thereof should be set to be parallel to the another-vehicle direction D2. Therefore, as illustrated in FIG. 6, when the angle formed by the own-vehicle direction D1 and the another-vehicle direction D2 is not a right angle, an appropriate longitudinal direction of the parking area A is angled with respect to the own-vehicle direction D1. However, when it is difficult to acquire obstacle information (distance information or the like) regarding the rear portion of the another vehicle 70 due to a limit of a detection range of the ultrasonic sensors