Road structure – process – or apparatus – Apparatus – Automatic control
Reexamination Certificate
1997-11-10
2001-01-09
Lillis, Eileen D. (Department: 3673)
Road structure, process, or apparatus
Apparatus
Automatic control
C404S084100
Reexamination Certificate
active
06171018
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in an automatic control system for construction machines which automatically perform leveling of ground and paving. The construction machines are used in the civil engineering and construction field and include, for example, motor graders, pavers, and bulldozers.
2. Description of the Related Art
In the civil engineering and construction field, the ground leveling implements of a construction machine, such as a blade and a screed, are automatically controlled in performing ground leveling and paving.
In the system for automatically controlling a ground leveling implement that is used in a construction machine, a ground leveling string corresponding to a finished cross section is stretched over the construction site in order to obtain an expected finished surface. The interval between the ground leveling string and the ground leveling implement is detected with a contact type cantilever or a non-contact type ultrasonic sensor. Based on the detection result, the ground leveling implement is controlled so as to follow the ground leveling string by oil pressure. However, the system for automatically controlling a ground leveling implement so that the implement follows a ground leveling string requires a great deal of labor to stretch a ground leveling string over a construction site.
Hence, there has been proposed an automatic control system for construction machinery which is capable of automatically controlling a ground leveling implement and obtaining an expected finished surface without stretching a ground leveling string over a construction site.
An example of the aforementioned automatic control system is shown in FIG.
1
. In the figure, reference numeral
1
denotes a bulldozer which is a construction machine for leveling a construction site,
2
a rotating laser unit installed in a construction site,
3
a blade which is a ground leveling implement,
4
a pole stood up in the blade
3
, and
5
a laser sensor fixed to the pole
4
.
The rotating laser unit
2
forms a reference plane Rs at a position of a predetermined height (h) away from a finished plane
6
by means of a generated laser beam. The blade
3
is controlled so that the laser light from the rotating laser unit
2
strikes against the vertical center Ho of the laser sensor
5
(center Ho in the height direction of the laser sensor
5
), by an oil pressure control unit
7
serving as ground leveling implement control means. In this way, the ground of a construction site is leveled to an expected finished plane
6
. According to this automatic control system for construction machines, a ground leveling operation and a paving operation can be simply performed compared with an operation of stretching a ground leveling string over a construction site.
However, in the case where the ground
6
′ and finished plane
6
of a construction site have a complicated configuration with undulations and inclination, the rotating laser unit
2
has to be reinstalled as shown in
FIG. 2
in order to obtain the reference plane Rs. For this reason, in the case of the leveling and paving of complicated ground, there will arise the problem that the operation for reinstalling the rotating laser unit
2
will be troublesome.
Hence, another system for automatically controlling the construction machine
1
has been proposed. This system employs an automatic tracking type survey unit, also called a total tracking station (which is available as “AP-L1” manufactured by TOPCON). The automatic tracking type survey unit measures a distance to a target, a horizontal angle between a reference direction and a direction in which the target exists, and a vertical angle between a reference height and a direction in which the target exists, and tracks the target.
FIG. 3
illustrates an example of the system for automatically controlling a construction machine by employing an automatic tracking type survey unit. In the figure, reference numeral
8
denotes an automatic tracking type survey unit, which is installed at the known coordinate point O of a construction block. The survey unit
8
is connected to a personal computer (PC)
9
, which is in turn connected to a radio transmitter
10
. A bulldozer
1
is provided with a blade
3
, a pole
4
stood up in the blade
3
, an oil pressure control unit
7
, a prism
11
attached to the pole
4
as a target to be tracked, and a radio receiver
12
.
The PC
9
stores finished-height data in correspondence with each horizontal coordinate position in the construction block. The survey unit
8
tracks the prism
11
and measures the distance from the known coordinate position O to the prism
11
and the horizontal angle between a reference direction and a direction in which the prism
11
exists. Based on the measured distance and horizontal angle, the survey unit
8
computes the coordinate position data or horizontal coordinate position data of the prism
11
(target) relative to the known coordinate O. The computed coordinate position data or horizontal coordinate position data is transferred from the survey unit
8
to the PC
9
.
The PC
9
calls out finished-height data corresponding to the computed horizontal coordinate position, that is, finished-height data relative to the known coordinate point O. Then, the PC
9
transfers the finished-height data to the radio transmitter
10
. The radio transmitter
10
transmits the finished-height data to the radio receiver
12
. The oil pressure control unit
7
controls the blade
3
, based on the finished-height data received by the radio receiver
12
. The blade
3
digs or cuts ground so that the ground has a designed finished height (construction height). Note that the aforementioned finished-height data is referred to as a height relative to known coordinate point O.
The system for automatically controlling a construction machine with the automatic tracking type survey unit
8
has the advantage that the finished plane of complicated ground can be created without increasing the number of steps, because the blade
3
is controlled based on finished-height data (construction data).
However, it is to be desired that, after a construction task is completed, construction evaluation can be performed by comparing an actually finished plane with each finished-height data, because a finished height is indicated by the use of the personal computer in which the finished-height data is stored per each horizontal coordinate position.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an automatic control system for a construction machine which is capable of gathering data for performing construction evaluation when a finishing operation is conducted.
To achieve this end, there is provided an automatic control system for a construction machine, comprising: a construction machine situated on a construction site and provided with a ground leveling implement, a target, and a laser sensor; a survey unit for projecting a laser beam indicating a finished-plane height toward the laser sensor, the survey unit having coordinate position measuring means for optically measuring a coordinate position of the target; storage means for storing finished-plane height data in correspondence with a horizontal coordinate position in the coordinate position; and computation means for computing a finished-plane height at the horizontal coordinate position, based on determined finished-plane height data. In the automatic control system, the survey unit is equipped with rotation means for rotating the laser beam in a vertical direction so that a height of the laser beam at the horizontal coordinate position becomes a height from a determined finished plane. The construction machine is provided with control means for controlling the ground leveling implement so that the ground leveling implement reaches the finished-plane height, based on a position at which the laser beam is received on the laser sensor. The computation means computes a deviation
Brabec Vernon J.
Hirano Satoshi
Kimura Kazuaki
Ohtomo Fumio
Omori Makoto
Addie Ramond W
Kabushiki Kaisha Topcon
Lillis Eileen D.
Limbach & Limbach LLP
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