Work machine

Patent metadata

Field	Value
Publication number	US-12252869-B2
Application number	US-202017297007-A
Country	US
Kind code	B2
Filing date	Feb 12, 2020
Priority date	Mar 22, 2019
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

To provide a work machine that enables enhancement of shaping accuracy near a boundary line between two adjacent target surfaces. A controller 10 extracts, from among a plurality of target surfaces, a second target surface S2 that is a target surface adjacent to a first target surface S1, calculates a boundary line L2 between the first target surface S1 and the second target surface S2, and, prior to a work tool 6 passing the first boundary line L2, corrects a control signal for a posture control actuator 6c such that the angular difference EL between a reference line L1 set on the work tool 6 and the boundary line L2 becomes small.

First claim

The invention claimed is:

1. A work machine comprising:
a bucket;
a plurality of actuators including at least one position control actuator that controls a position of the bucket and at least one posture control actuator that controls posture of the bucket;
an operation device that instructs the plurality of actuators about operations of the actuators;
a controller that outputs a control signal for controlling at least one of the plurality of actuators on a basis of an operation amount of the operation device; and
a design surface storage device that stores information concerning design surfaces including a plurality of target surfaces,
the controller being configured to extract a first target surface which is a target surface nearest to the bucket, from among the plurality of target surfaces, and control an operation velocity of at least one actuator of the plurality of actuators on a basis of the position and posture of the bucket relative to the first target surface, wherein
the posture control actuator is a rotary motor that rotates the bucket, and
when the bucket is moved along the first target surface with a cutting edge of the bucket in a line contact state with the first target surface by controlling the position control actuator on a basis of an operation amount of the operation device for the position control actuator, the controller is configured to:
extract a second target surface which is a target surface adjacent to the first target surface, from among the plurality of target surfaces,
calculate a first boundary line which is a boundary line between the first target surface and the second target surface,

calculate an angular difference between a reference line and the first boundary line, the reference line being set as a straight line passing through a left end point and a right end point of the cutting edge of the bucket, and
prior to the cutting edge of the bucket passing the first boundary line, correct a rotational angle of the rotary motor such that the angular difference becomes small and thereby the reference line comes into the line contact state with the second target surface after passing the first boundary line.

2. The work machine according to claim 1 , wherein
the controller is configured to, when correcting the rotational angle of the rotary motor, correct the control signal for the position control actuator such that degree of deceleration of an operating velocity of the bucket on a direction toward the first boundary line is larger as the angular difference is larger.

3. The work machine according to claim 1 , wherein the controller is configured to
calculate a first boundary line distance which is a distance from a reference point set on the cutting edge of the bucket to the first boundary line, and
when the first boundary distance is less than a threshold, correct the rotational angle of the rotary motor such that the angular difference becomes small.

4. The work machine according to claim 1 , wherein the controller is configured to
calculate a first boundary line distance which is a distance from a reference point set on the cutting edge of the bucket to the first boundary line, and
when the first boundary line distance is less than a threshold, correct the control signal for the position control actuator such that a moving velocity of the bucket becomes equal to or less than a limited velocity.

5. The work machine according to claim 1 , wherein the controller is configured to
calculate a boundary line approaching velocity which is a velocity component in a direction toward the first boundary line of an operating velocity of the bucket, and
when the boundary line approaching velocity is equal to or more than a threshold, correct the control signal for the position control actuator such that a moving velocity of the bucket becomes equal to or less than a limited velocity.

6. The work machine according to claim 1 , wherein the controller is configured to
extract a third target surface which is a target surface adjacent to the first target surface separately from the second target surface, from among the plurality of target surfaces,
calculate a second boundary line which is a boundary line between the first target surface and the third target surface,
calculate a first boundary line distance which is a distance from a reference point set on the cutting edge of the bucket to the first boundary line,
calculate a second boundary line distance which is a distance from the reference point to the second boundary line, and
when both the first boundary line distance and the second boundary line distance are less than a threshold, stop correction of the rotational angle of the rotary motor.

Assignees

• Hitachi Construction Mach Co

Inventors

• Kanazawa Akira
• Moriki Hidekazu
• Imura Shinya
• Izumi Shiho
• Chiba Takaaki

Classifications

• E02F3/435

  for dipper-arms, backhoes or the like · CPC title

• E02F9/2203

  Arrangements for controlling the attitude of actuators, e.g. speed, floating function · CPC title

• E02F3/3681

  Rotators · CPC title

• E02F9/2296

  Systems with a variable displacement pump · CPC title

• E02F9/2285

  Pilot-operated systems · CPC title