US-12617406-B2 - Travel control device, travel control method, and storage medium storing travel control program

Abstract

A travel control device is configured to execute: a coasting travel process; a cruise travel process, a gradient information acquisition process acquiring, as gradient information, information indicating a gradient of a road surface on which a vehicle is traveling; a deviation variable acquisition process acquiring a deviation variable for determining an acceleration generated in the vehicle when the vehicle travels, by performing the coasting travel process, a downward slope having a predetermined gradient; and a switching process using the gradient information and the deviation variable as inputs and performing switching to the coasting travel process according to a value of the deviation variable even though a magnitude of the gradient of the road surface is different from a reference value.

Inventors

• Yuuki Ozawa
• Riku Koyama

Assignees

• J-QuAD DYNAMICS INC.

Dates

Publication Date

20260505

Application Date

20240426

Priority Date

20211029

Claims (6)

1. 1 . A travel control device comprising: a computer; and a non-transitory storage device, wherein the computer, by executing a control program stored in the non-transitory storage device, is configured to execute: a coasting travel process; a cruise travel process; a gradient information acquisition process; a deviation variable acquisition process; and a switching process, the coasting travel process performs a coasting travel of a vehicle, the cruise travel process controls a speed of the vehicle to a set vehicle speed while giving a priority to satisfaction of a predetermined condition, the predetermined condition is a condition for maintaining a distance to a preceding vehicle within a predetermined distance range when the preceding vehicle is located within a predetermined range ahead of the vehicle, the gradient information acquisition process acquires, as gradient information, information indicating a gradient of a road surface on which the vehicle is traveling, the deviation variable acquisition process acquires, separately from the gradient information, a deviation variable for determining an acceleration generated in the vehicle when the vehicle travels, by performing the coasting travel process, a downward slope having a predetermined gradient, the switching process uses the gradient information and the deviation variable as inputs and performs switching to the coasting travel process when the vehicle travels the downward slope while the cruise travel process is being executed, the switching process performs switching to the coasting travel process according to a value of the deviation variable even though a magnitude of the gradient of the road surface is smaller than a reference value, the deviation variable includes a variable indicating whether the vehicle is traveling in a one-way tunnel, and the switching process performs switching to the coasting travel process when the deviation variable indicates that the vehicle is traveling in the one-way tunnel, even though the magnitude of the gradient of the road surface is smaller than the reference value set for a traveling outside the one-way tunnel.
2. 2 . The travel control device according to claim 1 , wherein the switching process accelerates the vehicle by executing the coasting travel process.
3. 3 . The travel control device according to claim 1 , wherein the switching process performs switching to the coasting travel process when the vehicle travels the downward slope using the gradient information of the road surface on which the vehicle is predicted to travel after the vehicle advances a predetermined distance as an input.
4. 4 . The travel control device according to claim 1 , wherein the deviation variable includes a variable indicating one or more weights of one or more occupants of the vehicle, and the switching process performs switching to the coasting travel process when a number of the one or more occupants is smaller than a reference number, even though the magnitude of the gradient of the road surface is smaller than a reference value set for the reference number of the one or more occupants.
5. 5 . A travel control method comprising steps for executing the processes described in claim 1 .
6. 6 . A non-transitory storage medium storing a travel control program, the travel control program comprising instructions for executing, using a computer, the processes described in claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of International Patent Application No. PCT/JP2022/039580 filed on Oct. 24, 2022, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2021-177588 filed on Oct. 29, 2021. The entire disclosures of all of the above applications are incorporated herein by reference. TECHNICAL FIELD The present disclosure relates to a travel control device, a travel control method, and a storage medium storing a travel control program. BACKGROUND A known travel control device switches a travel mode of a vehicle to coasting travel during cruise control. The travel control device determines a switch time to coasting travel and a time to end the coasting travel in accordance with an inter-vehicle time, which is the time required for a host vehicle to travel a distance between the host vehicle and a preceding vehicle. SUMMARY A travel control device is configured to perform: a coasting travel process; a cruise travel process; a gradient information acquisition process; a deviation variable acquisition process; and a switching process. The coasting travel process performs a coasting travel of a vehicle. The cruise travel process controls a speed of the vehicle to a set vehicle speed while giving a priority to satisfaction of a predetermined condition. The predetermined condition is a condition for maintaining a distance to a preceding vehicle within a predetermined distance range when the preceding vehicle is located within a predetermined range ahead of the vehicle. The gradient information acquisition process acquires, as gradient information, information indicating a gradient of a road surface on which the vehicle is traveling. The deviation variable acquisition process acquires, separately from the gradient information, a deviation variable for determining an acceleration generated in the vehicle when the vehicle travels, by performing the coasting travel process, a downward slope having a predetermined gradient. The switching process uses the gradient information and the deviation variable as inputs and performs switching to the coasting travel process when the vehicle travels the downward slope while the cruise travel process is being executed, the switching process performs switching to the coasting travel process according to a value of the deviation variable even though a magnitude of the gradient of the road surface is different from a reference value. BRIEF DESCRIPTION OF DRAWINGS The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: FIG. 1 is a diagram showing a configuration of a travel control system according to an embodiment; FIG. 2 is a flowchart showing a procedure of process executed by a control device according to the first embodiment; FIG. 3 is a flowchart showing a procedure of process executed by the control device according to the first embodiment; FIG. 4 is a flowchart showing a procedure of process executed by the control device according to the first embodiment; FIG. 5A and FIG. 5B are diagrams showing examples in which switching is determined according to inside or outside of one-way tunnel; FIG. 6 is a flowchart showing a procedure of process executed by a control device according to a second embodiment; and FIG. 7 is a flowchart showing the procedure of process executed by a control device according to a third embodiment. DETAILED DESCRIPTION The coasting travel is effective in reducing energy consumption rate of the vehicle. However, the above-mentioned device cannot sufficiently reduce the energy consumption rate when the vehicle is traveling a downward slope. According to an aspect of the present disclosure, a travel control device includes a computer and a non-transitory storage device. The computer, by executing a control program stored in the non-transitory storage device, is configured to execute: a coasting travel process; a cruise travel process; a gradient information acquisition process; a deviation variable acquisition process; and a switching process. The coasting travel process performs a coasting travel of a vehicle. The cruise travel process controls a speed of the vehicle to a set vehicle speed while giving a priority to satisfaction of a predetermined condition. The predetermined condition is a condition for maintaining a distance to a preceding vehicle within a predetermined distance range when the preceding vehicle is located within a predetermined range ahead of the vehicle. The gradient information acquisition process acquires, as gradient information, information indicating a gradient of a road surface on which the vehicle is traveling. The deviation variable acquisition process acquires, separately from the gradient information, a deviation variable for determining an acceleration gener