Excavating – Scoop or excavating and transporting container – Supported on vehicle between longitudinally spaced ground...
Patent
1998-07-20
2000-08-08
Novosad, Christopher J.
Excavating
Scoop or excavating and transporting container
Supported on vehicle between longitudinally spaced ground...
37443, 701 50, E02F 343, E02F 922
Patent
active
060983221
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a construction machine such as a hydraulic excavator for excavating the ground, and more particularly to a control apparatus for a construction machine of the type mentioned.
BACKGROUND ART
Generally, a construction machine such as a hydraulic excavator has a construction wherein it includes, for example, as shown in FIG. 14, an upper revolving unit 100 with an operator cab (cabin) 600 provided on a lower traveling body 500 having caterpillar members 500A, and further, a joint type arm mechanism composed of a boom 200, a stick 300 and a bucket 400 is provided on the upper revolving unit 100.
And, based on extension/contraction displacement information of the boom 200, stick 300 and bucket 400 obtained by stroke sensors 210, 220, 230 and so forth, the boom 200, stick 300 and bucket 400 can be driven suitably by hydraulic cylinders 120, 121 and 122, respectively, to perform an excavating operation while keeping the advancing direction of the bucket 400 or the posture of the bucket 400 fixed so that control of the position and the posture of a working member such as the bucket 400 can be performed accurately and stably.
It is to be noted that the hydraulic cylinders 120 to 122 are operated by operation levers (not shown) normally provided in the operator cab 600.
By the way, a semiautomatic control system for such a construction machine as described above has been proposed wherein the boom 200, stick 300, bucket 400 and so forth are set so that they may perform a sequence of operations set in advance and the hydraulic cylinders 120, 121 and 122 are controlled individually so that their operations set in this manner may be performed.
Here, as the semiautomatic control mode described above, a bucket angle control mode in which the angle (bucket angle) of the bucket 400 with respect to a horizontal direction (vertical direction) is always kept fixed even if the stick 300 and the boom 200 are moved, a slope face excavation mode (bucket tip linear excavation mode or raking mode) in which a tip 112 of the bucket 400 moves linearly, and so forth are available.
By the way, in such semiconductor control modes as described above, the operation levers for controlling the operations of the hydraulic cylinders 120 to 122 function as members for setting target moving velocities for the stick 300 and the boom 200.
In particular, in a semiautomatic control mode, the moving speeds of the stick 300 and the boom 200 are determined in response to operation amounts of the operation levers.
However, a semiautomatic system applied to a conventional construction machine has such various subjects as given below.
(1) If an operator operates an operation lever suddenly upon starting of working in a semiautomatic control mode, then control instruction values to the hydraulic cylinders 120 to 122 of the boom 200, stick 300 and bucket 400 vary instantly, and it is considered that the load may be applied suddenly to the hydraulic cylinders 120, 121 and 122. In this instance, there is the possibility that the hydraulic cylinder 120, 121 or 122 may not operate smoothly but operate while accompanying a light impact, vibrations, a shock or the like, and further, there is the possibility that the accuracy of the locus of the bucket tip position may be deteriorated.
In order to eliminate such a situation as described above, it is a possible idea to increase the moving velocity of the bucket tip gradually (ramp up process) or give a smooth velocity variation through a low-pass filter even if an operation lever is operated suddenly. However, in a semiautomatic control mode, since control signals to the hydraulic cylinders are fed-back information obtained by time differentiating the cylinder positions, even if such a ramp up process as mentioned above or the like is performed, the instruction values to the hydraulic cylinders vary discontinuously depending upon the time differentiation information of the cylinder positions. Consequently, there still is a subject that the boom, stick or bucket does not
Ono Tomoaki
Tozawa Shoji
Novosad Christopher J.
Shin Caterpillar Mitsubishi Ltd.
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