Work machine

Patent metadata

Field	Value
Publication number	US-10801187-B2
Application number	US-201716090605-A
Country	US
Kind code	B2
Filing date	Feb 28, 2017
Priority date	Jun 30, 2016
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

Provided is a work machine that is equipped with a control unit that executes area limiting control with respect to a work device. The control unit includes: a position computing section that calculates the position, on an operation plane, of the forward end (first reference point) of a bucket and the rear end (second reference point) of the bucket; and a first distance computing section that calculates the distances in the operating plane from the first reference point and the second reference point to the target face A to be controlled. When the smaller one of the two distances is equal to or lower than a threshold during area limiting control, the control unit corrects an operation signal output from an operation lever device so as to reduce the operating speed of a hydraulic actuator that is a control target of the operation signal.

First claim

The invention claimed is:

1. A work machine comprising:
a multi-joint type work device formed by connecting a plurality of driven members and configured to operate in a predetermined operational plane;
a plurality of hydraulic actuators each driving corresponding one of the plurality of driven members on the basis of an operation signal;
an operation device outputting the operation signal to a hydraulic actuator desired by an operator among the plurality of hydraulic actuators; and
a controller that executes area limiting control such that the work device moves on a target surface of a control object and in an area above the target surface, by outputting the operation signal to at least one hydraulic actuator among the plurality of hydraulic actuators or by outputting a corrected operation signal to said at least one hydraulic actuator,
wherein the controller is configured to:
store two segments that are connected at a different angle in the operational plane and that can be the target surface of the control object, a position of an inflection point that is an intersection of the two segments in the operational plane, and a first reference point and a second reference point set at a distal end portion of the work device;
calculate positions of the first reference point and the second reference point in the operational plane on the basis of a posture of the work device, and
calculate distances from the first reference point and the second reference point in the operational plane to the target surface of the control object, calculate positions in the operational plane of two projection points obtained through projection of the first reference point and the second reference point onto the target surface of the control object, and calculate the distances from the positions of the two projection points in the operational plane to the inflection point;
when a smaller one of the distances from the first reference point and the second reference point to the target surface of the control object is larger than a threshold value, output the operation signal to said at least one hydraulic actuator; and
when the smaller one of the distances from the first reference point and the second reference point to the target surface of the control object is equal to or lower than a threshold value, correct the operation signal such that the operational speed of said at least one hydraulic actuator is reduced by a larger amount as a smaller one of the distances from the two projection points to the inflection point becomes smaller.

2. The work machine according to claim 1 ,
wherein the controller is configured to:
determine whether or not the inflection point exists between the two projection points on the target surface of the control object and in the extension thereof, and
when the smaller one of the distances from the first reference point and the second reference point to the target surface of the control object is equal to or lower than the threshold value, and when the controller determines that the inflection point exists between the two projection points,
correct the operation signal such that the reduction degree of the operational speed of the hydraulic actuator constituting the control target of operation signal is set to a value equal to or more than a maximum value of the reduction degree set based on the smaller one of the distances from the two projection points to the inflection point.

3. The work machine according to claim 1 ,
wherein the controller is configured to:
calculate an angle change amount which is an absolute value of a difference between a target surface angle of the target surface constituting the control object and a target surface angle of a target surface constituting a next control object, and
when the controller reduces the operational speed of the hydraulic actuator constituting the control target of the operation signal,
set a reduction degree of the operational speed to be larger as the angle change amount becomes larger.

Assignees

• Hitachi Construction Mach Co

Inventors

• Izumi Shiho
• NARIKAWA Ryuu
• Ishikawa Kouji
• SAKAI Daito
• Kurose Takahiko

Classifications

• E02F9/2033 Primary

  Limiting the movement of frames or implements, e.g. to avoid collision between implements and the cabin (sub-groups of E02F3/431 of E02F3/435 take precedence; for turntables E02F9/123) · CPC title

• E02F3/435 Primary

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

• E02F9/2271

  Actuators and supports therefor and protection therefor · CPC title

• E02F3/43

  Control of dipper or bucket position; Control of sequence of drive operations · CPC title

• E02F9/265 Primary

  with follow-up actions (e.g. control signals sent to actuate the work tool) · CPC title