Shovel
A shovel includes a lower traveling body, an upper turning body turnably mounted on the lower traveling body, an attachment including a boom attached to the upper turning body, an arm attached to an end of the boom, and an end attachment attached to an end of the arm, wherein a motion of the arm or the end attachment is corrected according to a stability of a body of the shovel.
1 . A shovel comprising:
a lower traveling body:
an upper turning body turnably mounted on the lower traveling body;
an attachment including a boom attached to the upper turning body, an arm attached to an end of the boom, and an end attachment attached to an end of the arm;
an arm cylinder configured to drive the arm;
a hydraulic pump configured to supply hydraulic oil to the arm cylinder;
a relief valve configured to release a pressure of the hydraulic oil in a rod-side oil chamber of the arm cylinder; and
a hardware processor configured to correct a motion of the arm or the end attachment according to a stability of a body of the shovel during aerial motion of the attachment,
wherein the hardware processor is configured to, in a case of correcting the motion of the arm, correct the motion of the arm to move the arm in a closing direction, in response to identifying a predetermined motion of the shovel that causes the body of the shovel to be in an unstable state,
the hardware processor is configured to, in response to identifying the predetermined motion of the shovel, cause the relief valve to release the pressure in the rod-side oil chamber of the arm cylinder by discharging the hydraulic oil in the rod-side oil chamber of the arm cylinder to a hydraulic oil tank, to allow the arm to be moved in the closing direction by a weight of the arm during the aerial motion of the attachment,
a stable range of the attachment where a degree of static stability of the attachment is more than or equal to a predetermined reference is defined around the shovel,
the stable range is an area surrounding the lower traveling body in a plane in which the lower traveling body is positioned, and an outer edge of the stable range is spaced apart from the lower traveling body, and
the hardware processor is configured to determine whether a position of the end attachment relative to the lower traveling body is beyond the outer edge of the stable range, and to determine that the body of the shovel is in a static unstable state in response to determining that the position of the end attachment relative to the lower traveling body is beyond the outer edge of the stable range.
2 . The shovel according to claim 1 , wherein
the hardware processor is configured to
move the arm and the end attachment according to an operation content or a motion instruction of an automatic drive function when the body is in a stable state, and
correct the motion of the arm or the end attachment in such a manner as to recover the stability compared with the motion according to the operation content or the motion instruction when the body is in an unstable state including the static unstable state.
3 . The shovel according to claim 1 , wherein the hardware processor is configured to move the arm in the closing direction so as to reduce a possibility of a dynamic moment exerted on the body including the lower traveling body and the upper turning body, in response to identifying the predetermined motion of the shovel.
4 . The shovel according to claim 3 , wherein the predetermined motion includes: a motion in which the attachment unloads an object loaded in a bucket serving as the end attachment; a motion in which the lower traveling body rapidly decelerates while the lower traveling body is traveling with the attachment being oriented in a traveling direction: or a motion of increasing an amount of a forward tilt of the body while the lower traveling body is traveling with the attachment being oriented in the traveling direction, or includes two or more thereof.
5 . The shovel according to claim 1 , wherein the hardware processor is configured to move the arm in the closing direction so as to reduce a change in a static moment exerted on the body including the lower traveling body and the upper turning body.
6 . The shovel according to claim 5 , wherein the predetermined motion includes: a lowering motion for lowering the boom while a distance between the end attachment and the body is more than a predetermined threshold value; a motion in which the attachment loads and raises a target object on a bucket serving as the end attachment: a motion of turning the upper turning body so that a direction of the attachment moves away from a traveling direction of the lower traveling body: or a motion in which an amount of forward tilt of the body increases while the lower traveling body is traveling with the attachment being oriented in the traveling direction, or includes two or more thereof.
7 . The shovel according to claim 1 , wherein the hardware processor is configured to slow an opening motion of the end attachment in response to determining that there is a possibility or an occurrence of a lift of a rear part of the lower traveling body.
8 . The shovel according to claim 7 , wherein the hardware processor is configured to slow the opening motion of the end attachment in response to determining that a weight of the end attachment is larger than a predetermined value, or in response to determining that a distance between the position of the end attachment and the lower traveling body is more than a predetermined threshold value.
9 . The shovel according to claim 7 , wherein the end attachment is a bucket, and the hardware processor is configured to slow an opening motion of the bucket when the attachment makes a movement of unloading an object loaded in the bucket.
10 . The shovel according to claim 9 , wherein the hardware processor is configured to slow the opening motion of the bucket in response to determining that a distance between a position of the bucket and the lower traveling body is more than a predetermined threshold value when the attachment makes the movement of unloading.
11 . The shovel according to claim 9 , wherein the hardware processor is configured to slow the opening motion of the bucket in response to determining that there is the possibility or the occurrence of the lift of the rear part of the lower traveling body when the attachment makes the movement of unloading.
12 . The shovel according to claim 7 , further comprising:
an end attachment cylinder configured to drive the end attachment,
wherein the hydraulic pump is configured to supply the hydraulic oil to the end attachment cylinder, and
the hardware processor is configured to slow the opening motion of the end attachment by: limiting a discharge flowrate of the hydraulic pump supplying the hydraulic oil to the end attachment cylinder; causing a control valve configured to control a flowrate of the hydraulic oil supplied from the hydraulic pump to the end attachment cylinder to limit the flowrate of the hydraulic oil to the end attachment cylinder; or causing a throttle valve provided in a hydraulic path between the control valve and the end attachment cylinder to reduce a flowrate of the hydraulic oil discharged from the end attachment cylinder.
13 . The shovel according to claim 12 , wherein the hardware processor is configured to slow the opening motion of the end attachment by limiting a movement velocity or a movement acceleration of the end attachment cylinder to a predetermined upper limit value or less or limiting both of the movement velocity or the movement acceleration to the predetermined upper limit value or less.
14 . The shovel according to claim 13 , further comprising:
a predetermined sensor configured to detect a state of the attachment,
wherein the hardware processor is configured to calculate the predetermined upper limit value based on detection information of the predetermined sensor.
15 . The shovel according to claim 14 , wherein the hardware processor is configured to calculate an overturning moment in a direction to lift up the rear part of the lower traveling body and a restraining moment in a direction to restrain lifting up of the rear part of the lower traveling body based on the detection information of the predetermined sensor, and to calculate the predetermined upper limit value so that the overturning moment falls below the restraining moment.
16 . The shovel according to claim 1 , wherein
the end attachment is a bucket,
the hardware processor is configured to correct the motion of the arm to move the arm in the closing direction while the bucket is opening during the aerial motion of the attachment, and
the hardware processor is configured to slow an opening of the bucket while moving the arm in the closing direction.
17 . The shovel according to claim 16 , further comprising:
a bucket cylinder configured to drive the bucket,
wherein the hardware processor is configured to slow the opening of the bucket by limiting a movement acceleration of the bucket cylinder to an upper limit movement acceleration.
18 . The shovel according to claim 17 , wherein the hardware processor is configured to slow the opening of the bucket by further limiting a movement velocity of the bucket cylinder to an upper limit movement velocity after limiting the movement acceleration of the bucket cylinder to the upper limit movement acceleration.
19 . The shovel according to claim 1 , wherein
the hydraulic pump is a variable displacement hydraulic pump and is configured to supply the hydraulic oil to the rod-side oil chamber of the arm cylinder, and
the relief valve is configured to discharge the hydraulic oil in the rod-side oil chamber of the arm cylinder supplied by the hydraulic pump.
20 . The shovel according to claim 1 , wherein the outer edge of the stable range is defined by a first side, a second side, a third side, and a fourth side, the first side curving toward a front side of the lower traveling body, the second side curving toward a rear side of the lower traveling body, the third side curving toward a left side of the lower traveling body, the fourth side curving toward a right side of the lower traveling body.