Control system for work vehicle, method, and work vehicle

1. A control system for a work vehicle including a work implement, the control system comprising

a controller that controls the work implement, the controller being configured to obtain a final design topography,

determine a target design topography, at least a portion of the target design topography being positioned above the final design topography,

generate a command signal to operate the work implement in accordance with the target design topography,

determine whether at least a portion of the target design topography is positioned below the final design topography,

change the target design topography such that an entirety of the target design topography is positioned at or above the final design topography when it is determined that at least a portion of the target design topography is positioned below the final design topography, and

control the work implement in accordance with the command signal such that the work implement follows the target design topography.

2. The control system for a work vehicle according to claim 1 , wherein

the controller is further configured to

determine a target tilt angle,

generate the command signal to operate the work implement in accordance with the target design topography at the target tilt angle.

3. The control system for a work vehicle according to claim 1 , wherein

the controller is configured to change the target tilt angle to change the target design topography such that the entirety of the target design topography is positioned at or above the final design topography.

4. The control system for a work vehicle according to claim 3 , further comprising:

an operating device that outputs an operation signal indicating an operation by an operator,

the controller being further configured to

receive the operation signal from the operating device,

when the tilt angle of the work implement is changed due to an operation of the operating device, correct the target tilt angle of the work implement in accordance with the changed tilt angle, and

when at least a portion of the target design topography is positioned below the final design topography, prioritize

correcting the target tilt angle so that the entire target design topography is positioned at or above the final design topography, over

correcting the target tilt angle according to the operation of the operating device.

5. The control system for a work vehicle according to claim 2 , wherein

the controller is further configured to determine an initial value of the target tilt angle in accordance with the final design topography.

6. The control system for a work vehicle according to claim 1 , wherein

the target design topography indicates a target shape of a topography.

7. A control system for a work vehicle including a work implement, the control system comprising

a controller that controls the work implement, the controller being configured to obtain a first design topography,

determine a second design topography, at least a portion of the target design topography being positioned above the first design topography,

determine a target tilt angle,

generate a command signal to operate the work implement in accordance with the second design topography at the target tilt angle, and

change the second design topography when at least a portion of the second design topography is positioned below the first design topography,

the controller being further configured to determine an initial value of the target tilt angle in accordance with the first design topography so that the work implement becomes parallel to the first design topography.

8. A method executed by a controller for controlling a work vehicle including a work implement, the method comprising:

obtaining a final design topography;

determining a target design topography, at least a portion of the target design topography being positioned above the final design topography;

generating a command signal to operate the work implement in accordance with the target design topography;

determining whether at least a portion of the target design topography is positioned below the final design topography;

changing the target design topography such that an entirety of the target design topography is positioned at or above the final design topography when it is determined that at least a portion of the target design topography is positioned below the final design topography; and

controlling the work implement in accordance with the command signal such that the work implement follows the target design topography.

9. The method according to claim 8 , further comprising:

determining a target tilt angle,

the generating the command signal to operate the work implement in accordance with the target design topography at the target tilt angle.

10. The method according to claim 9 , wherein

the changing the target design topography such that an entirety of the target design topography is positioned at or above the final design topography includes changing the target tilt angle so that the target design topography is positioned at or above the final design topography.

11. The method according to claim 10 , further comprising:

receiving an operation signal indicating an operation by an operator, from an operating device; and

when the tilt angle of the work implement is changed due to the operation of the operating device, correcting the target tilt angle of the work implement in accordance with the changed tilt angle,

when at least a portion of the target design topography is positioned below the final design topography,

correcting the target tilt angle so that the target design topography is positioned at or above the final design topography, is prioritized over

correcting the target tilt angle according to the operation of the operating device.

12. The method according to claim 9 , further comprising:

determining an initial value of the target tilt angle in accordance with the final design topography.

13. The method according to claim 12 , wherein

the determining the initial value of the target tilt angle includes determining the initial value of the target tilt angle so that the work implement becomes parallel to the final design topography.