Work vehicle, method of controlling work vehicle, and controller for work vehicle

A work vehicle comprising:

• a joint;
• an implement connected to the joint and including an implement tip opposite to the joint;
• an arm assembly including an arm distal end and arm proximal end opposite to the arm distal end, the arm distal end being connected to the joint to swingably support the implement;
• a vehicle body configured to swingably support the arm proximal end;
• a traveling device configured to move the vehicle body;
• a first hydraulic cylinder configured to control an implement direction from the joint to the implement tip;
• a second hydraulic cylinder configured to control an arm height which is a height of the arm distal end with respect to a ground contact surface of the traveling device in a height direction perpendicular to the traveling direction of the traveling device;
• a hydraulic circuit configured to control the first hydraulic cylinder and the second hydraulic cylinder;
• an implement posture detection sensor configured to detect the implement direction;
• an arm posture detection sensor configured to detect the arm height;
• a memory configured to store first information corresponding to a reference direction which is a standard of the implement direction, and second information corresponding to a reference height which is a standard of the arm height;
• control circuitry configured to control the hydraulic circuit;
• an input device configured to receive an instruction to perform automatic control for changing the implement direction and the arm height respectively to the reference direction and the reference height;
• and
• the control circuitry configured to
• control the hydraulic circuit so that the arm height and the implement direction respectively approach the reference height and the reference direction in response to the instruction received by the input device, and
• control the hydraulic circuit so that during the automatic control, the implement direction is changed to the reference direction when the arm height reaches a target height which is greater than the reference height,
• wherein the first information includes a first reference value of a first parameter, the first parameter representing the implement direction, the first reference value corresponding to the reference direction,
• wherein the second information includes a second reference value of a second parameter, the second parameter representing which indicates the arm height, the second reference value corresponding to the reference height, and
• wherein the control circuitry is configured to
• control the hydraulic circuit such that the first parameter and the second parameter respectively approach the first reference value and the second reference value in response to the instruction received by the input device, and
• control the hydraulic circuit such that the first parameter is changed to the first reference value when the arm height reaches the target height, wherein the first parameter includes a position of the first hydraulic cylinder,
• wherein the second parameter includes a position of the second hydraulic cylinder,
• wherein the control circuitry is configured to perform processes in response to the instruction received by the input device, the processes comprising:
• obtaining a first reference position, a second reference position, a second target position, a first initial position, and a second initial position, the first reference position being a position of the first hydraulic cylinder which corresponds to the reference direction, the second reference position being a position of the second hydraulic cylinder which corresponds to the reference height, the second target position being a position of the second hydraulic cylinder which corresponds to the target height, the first initial position being a position of the first hydraulic cylinder upon reception of the instruction, the second initial position being a position of the second hydraulic cylinder upon reception of the instruction;
• and
• controlling the hydraulic circuit, while a position of the first hydraulic cylinder is changed from the first initial position to the first reference position, such that the hydraulic circuit performs a target operation in which an absolute value of an amount of change in positions of the first hydraulic cylinder per unit time is set to an absolute value of an amount of change in the second hydraulic cylinder per unit time multiplied by a quotient, the quotient being an absolute value of a difference between the first reference position and the first initial position divided by an absolute value of a difference between the second target position and the second initial position.

A control method of a work vehicle, comprising:

• acquiring a reference direction which is a standard of an implement direction from a joint to an implement tip of an implement, the joint rotatably connecting the implement to an arm distal end of the work vehicle;
• acquiring a reference height which is a standard of an arm height which is a height of the implement tip with respect to a ground contact surface of a traveling device of the work vehicle in a height direction perpendicular to a traveling direction of the traveling device;
• controlling a second hydraulic cylinder of the work vehicle such that the arm height approaches the reference height in response to an instruction to perform automatic control to change the implement direction to the reference direction and to decrease the arm height to the reference height;
• controlling a first hydraulic cylinder of the work vehicle to change the implement direction in accordance with change in the arm height such that the implement direction is changed to the reference direction when the arm height reaches a target height which is greater than the reference height;
• and
• controlling the hydraulic circuit so that the position of the first hydraulic cylinder is unchanged until the arm height reaches the reference height while the arm height is below the target height.

A controller for a work vehicle, comprising:

• a memory configured to store a first reference value and a second reference value, the first reference value corresponding to a reference direction which is a standard of an implement direction of a first parameter, the first parameter representing the implement direction representing an implement direction to an implement tip of an implement from a joint that rotatably connects the implement, the second reference value corresponding to a reference height which is a standard of an arm height of a second parameter, the second parameter representing the arm height which is a height of the implement tip with respect to a ground contact surface of a traveling device of the work vehicle in a height direction perpendicular to a traveling direction of the traveling device;
• a processor configured to control a second hydraulic cylinder of the work vehicle such that the arm height approaches the reference height in response to an instruction to perform automatic control to change the implement direction to the reference direction and to decrease the arm height to the reference height;
• the processor being configured to control a first hydraulic cylinder of the work vehicle to change the implement direction in accordance with change in the arm height such that the implement direction is changed to the reference direction when the arm height reaches a target height which is greater than the reference height;
• and
• the processor being configured to control the hydraulic circuit so that the position of the first hydraulic cylinder is unchanged until the arm height reaches the reference height while the arm height is below the target height.