Work machine and control method for work machine
A wheel loader includes a vehicle body, a work implement, a bucket-to-ground angle detection section, and a control section. The work implement operates with respect to the vehicle body and includes a bucket or a fork. The bucket-to-ground angle detection section detects information on a tilt angle of the bucket or the fork with respect to a gravity direction. The control section controls the tilt angle of the bucket or the fork with respect to the gravity direction based on a detection value of the bucket-to-ground angle detection section.
1 . A wheel loader comprising:
a body including
a front frame to which a work implement is connected, the work implement being movably attached to the front frame and including an attachment,
a rear frame disposed behind the front frame,
front tires disposed on the front frame, and
rear tires disposed on the rear frame;
a plurality of sensors, the plurality of sensors being configured to detect information on an attachment-to-ground angle of the attachment with respect to a gravity direction, the plurality of sensors being further configured to detect an articulation angle of the front frame with respect to the rear frame; and
a controller including a processor and a storage, the controller being configured to calculate the attachment-to-ground angle by adjusting the information on the attachment-to-ground angle in accordance with the articulation angle,
the controller being configured to control the attachment-to-ground angle based on a detection value from the plurality of sensors such that the attachment-to-ground angle matches a target value,
the controller being configured to determine whether a posture of the work implement required to match the attachment-to-ground angle to the target value is within a moveable range of the work implement,
the controller being configured to execute a ground-reference control such that the attachment-to-ground angle is maintained constant at the target value when the posture of the work implement required to match the attachment-to-ground angle to the target value is within the movable range, and
the controller being configured to execute a vehicle-body-reference control such that an attachment-to-body angle of the attachment with respect to the body is maintained constant when the posture of the work implement required to match the attachment-to-ground angle to the target value is outside the movable range.
2 . The wheel loader according to claim 1 , wherein
the plurality of sensors is configured to
detect a body tilt angle of the body with respect to the gravity direction, and
detect information on a relative position of the attachment with respect to the body, and
the controller is configured to calculate the attachment-to-body angle from the information on the relative position and calculate the attachment-to-ground angle from the attachment-to-body angle and the body tilt angle.
3 . The wheel loader according to claim 2 , wherein
the work implement further includes a boom that is rotatably connected to the body,
the attachment is rotatably connected to the boom,
the plurality of sensors is configured to
detect information on a rotation angle of the boom, and
detect information on a rotation angle of the attachment, and
the controller is configured to calculate the attachment-to-body angle using the information on the rotation angle of the boom and the information on the rotation angle of the attachment.
4 . The wheel loader according to claim 1 , wherein
the work implement further includes a boom that is rotatably connected to the body,
the attachment is rotatably connected to the boom, and
the controller is configured to maintain the attachment-to-ground angle constant at the target value when the boom is raised.
5 . The wheel loader according to claim 1 , wherein
the plurality of sensors is further configured to detect a relative position of the attachment with respect to the body, and
the controller is configured to control the attachment-to-ground angle based on the information on the attachment-to-ground angle and the relative position of the attachment with respect to the body.
6 . A control method for a work machine that includes a body and a work implement that has an attachment and is movably attached to the body,
the body including
a front frame to which the work implement is connected,
a rear frame disposed behind the front frame,
front tires disposed on the front frame, and
rear tires disposed on the rear frame,
the control method comprising using a controller and a plurality of sensors to perform the following:
detecting information on an attachment-to-ground angle of the attachment with respect to a gravity direction;
detecting an articulation angle of the front frame with respect to the rear frame,
calculating the attachment-to-ground angle by adjusting the information on the attachment-to-ground angle in accordance with the articulation angle;
controlling the attachment-to-ground angle such that the attachment-to-ground angle matches a target value;
determining whether a posture of the work implement required to match the attachment-to-ground angle to the target value is within a moveable range of the work implement;
executing a ground-reference control such that the attachment-to-ground angle is maintained constant at the target value when the posture of the work implement required to match the attachment-to-ground angle to the target value is within the movable range; and
executing a vehicle-body-reference control such that an attachment-to-body angle of the attachment with respect to the body is maintained constant when the posture of the work implement required to match the attachment-to-ground angle to the target value is outside the movable range.