Excavating – Ditcher – Condition responsive
Patent
1994-04-29
1995-09-05
Reese, Randolph A.
Excavating
Ditcher
Condition responsive
172 2, 36442407, G05D 102
Patent
active
054469813
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to construction equipment with a link-type working machine having a bucket or the like, such as a hydraulic power shovel, wherein path control of the tip of the working machine is carried out, and to a method of selecting an automatic operation mode for the working machine whereby a determination, of whether the control of an angle to the ground of the tip of the working machine should be carried out, is automatically made without requiring an input by an operator.
BACKGROUND ART
FIG. 1 shows a working machine of a hydraulic power shovel comprising a boom 1, an arm 2, a bucket 3, a boom cylinder 4, an arm cylinder 5, and a bucket cylinder 6. The boom 1, the arm 2, and the bucket 3 are moved by extending or contracting the cylinders 4, 5, or 6, respectively, causing a distal end of the bucket 3 to follow a predetermined path for excavation.
Conventionally, there are two modes of operation in automatic excavating path correction work by a hydraulic power shovel on a slope. In one mode (nose-fixed mode), as shown in FIG. 2A, the axes of the boom 1 and the arm 2 are activated in an interrelated manner to make the bucket nose excavate and finish a flat surface. In the other mode (fixed-angle to the ground mode), three axes, namely, the boom 1, the arm 2, and the bucket 3 are activated in an interrelated manner to perform excavation and surface finishing using a bottom surface of the bucket, as shown in FIG. 2B. Before beginning automatic operation, an operator must use a switch or the like to select between these two modes.
A prior art system for automatically selecting between the modes is disclosed in Japanese Patent Laid-Open No. 2-47432 publication, wherein a boom angle .theta..sub.1, an arm angle .theta..sub.2, a bucket angle .theta..sub.3, a body inclination .theta..sub.0, and a target excavating grade .theta., shown in FIG. 3 are inputted. An angle .beta. between the bottom surface of the bucket 3 and the flat surface, which is to be excavated, is determined at the beginning of the automatic operation from formula (1) below, and the computation result is compared with a predetermined value, thereby automatically determining the mode. +.theta..sub.3 +.theta.+.alpha.) (1)
Generally, in the case of the bucket used for the hydraulic power shovel, a standard tooth bucket shown in FIG. 4A needs to be replaced by various special buckets according to the particular work. On the other hand, however, a slope finishing bucket, shown in FIG. 4B, comes in an infinite number of shapes with more buckets being produced at general iron works, than genuine buckets produced by construction equipment manufacturers. Buckets produced by general iron works vary in dimensions from one bucket to another except for pin intervals of the buckets. In other words, the use of a method, wherein the mode is determined by determining the angle to the ground .beta. of the bucket bottom surface, poses a problem in that the nose angle .alpha. of the bucket must be corrected each time the bucket is changed except when a bucket having a predetermined shape is used.
Further, a problem arises when automatic operation is performed for purposes other than excavation. For example, if the position of a hook is linearly moved in suspension work, as shown in FIG. 5, the automatic determination by the described mode determination method erroneously selects the nose-fixed mode because of a significant difference between the target direction of movement and the orientation of the angle .beta. between the bottom surface of the bucket and the ground. This presents a problem in that the nose point moves as indicated by a solid line rather than moving along the path intended by the operator and indicated by a broken line.
Hence, in order to maintain the current angle to the ground .beta. when the direction of the movement of the working machine is given, the bucket 3 must be turned either to a dump truck side or an excavating side. For instance, as shown in FIG. 6A, if the angle of movement of the bucket 3 o
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Kamada Seiji
Kuromoto Kazunori
Takeda Shuh
Tochizawa Mamoru
Batson Victor
Kabushiki Kaisha Komatsu Seisakusho
Reese Randolph A.
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