Region limiting excavation control system for construction machi

Details Region limiting excavation control system for construction machi Region limiting excavation control system for construction machi

1996-01-31

1997-12-30

Melius, Terry Lee

Excavating

Ditcher

Condition responsive

172 4, 414699, 36442407, E02F 502

Patent

active

057016917

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a region limiting excavation control system for a construction machine, and more particularly to a region limiting excavation control system which is mounted on a construction machine such as a hydraulic excavator a multi-articulated front attachment which can perform excavation while limiting the region where the front attachment is movable.


BACKGROUND ART

There is known a hydraulic excavator type of construction machine. A hydraulic excavator is made up by a front attachment comprising a boom, an arm and a bucket which are each rotatable in the vertical direction, and a body comprising an upper structure and an undercarriage, the boom of the front attachment having its base end supported to a front portion of the upper structure. In such a hydraulic excavator, the front members such as the boom are operated by respective manual control levers. However, because the front members are coupled to each other in an articulated manner for pivotal motion, it is very difficult to carry out excavation work over a predetermined region by controlling the front members. In view of the above, a region limiting excavation control system is proposed in JP, A, 4-136324 for facilitating the excavation work. The proposed region limiting excavation control system comprises means for detecting a posture of a front attachment, means for calculating a position of the front attachment based on a signal from the detecting means, means for teaching an entrance forbidden region where the front attachment is inhibited from entering, lever gain calculating means for determining the distance d between the position of the front attachment and a boundary line of the taught entrance forbidden region, and outputting the product of a lever control signal multiplied by a function depending on the distance d that takes a value 1 when the distance d is greater than a certain value, and a value between 0 and 1 when it is smaller than the certain value, and actuator control means for controlling motion of an actuator in accordance with a signal from the lever gain calculating means. With the construction of the proposed system, since the lever control signal is restricted depending on the distance to the boundary line of the entrance forbidden region, even when the operator attempts to move the end of the bucket into the entrance forbidden region by mistake, the bucket end is smoothly stopped at the boundary line automatically, or on the way of movement of the bucket end to the boundary line, the operator can notice the movement approaching the entrance forbidden region, judging from a reduction in the speed of the front attachment, and return the
Further, JP, A, 63-219731 discloses a hydraulic excavator wherein a work limit position beyond which the work carried out by a front attachment may encounter any trouble is set, and an arm is controlled to return its end into a work permitted region if the arm end goes out of the work limit position.


DISCLOSURE OF THE INVENTION

However, the above-mentioned prior arts have problems as follows.
With the prior art disclosed in JP, A, 4-136324, since the lever gain calculating means outputs, to the actuator control means, the product of the lever control signal multiplied by the function depending on the distance d, the bucket end is gradually slowed down as it approaches the boundary of the entrance forbidden region, and is finally stopped at the boundary of the entrance forbidden region. Therefore, a shock that would otherwise be generated when the operator attempts to move the bucket end into the entrance forbidden region can be avoided. But, this prior art is arranged to reduce the speed of the bucket end such that the speed is always reduced regardless of the direction in which the bucket end is moving. Accordingly, when excavation is performed along the boundary of the entrance forbidden region, the digging speed in the direction along the boundary of the entrance forbidden region is also reduced as the bucket end approaches the entrance forbi

REFERENCES:
patent: 5198800 (1993-03-01), Tozawa et al.
patent: 5490081 (1996-02-01), Kuromoto et al.

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