[Technical Field]
[0001] The present invention relates to a apparatus and method for controlling work trajectory
of construction equipment, and particularly, to a trajectory controlling device and
method for construction equipment, capable of automatically operating in the most
suitable work trajectory at the point when an automated task is selected.
[Background Art]
[0002] In general, an excavator is configured with: respective work devices (for example,
a boom, an arm, and a bucket); a boom cylinder, an arm cylinder, and a bucket cylinder
for driving the work devices, respectively; a swing motor for the swing operation
of an excavator body; and a motor and a hydraulic pump for supplying compressed oil
as a power source to the respective cylinders. An excavator is hydraulic construction
equipment that performs excavating, ridging, stationary work, and many other types
of work.
[0003] In an excavator, after hydraulic oil drawn from a hydraulic tank is discharged by
means of a main pump, the amount of hydraulic flow and hydraulic pressure being supplied
to the boom cylinder, the arm cylinder, and the bucket cylinder is controlled by means
of a control valve that is switched according to the manipulation of a joystick, and
actuators actuate the boom, arm, bucket, etc. to enable an operator to perform a desired
task.
[0004] In order to perform various tasks with an excavator, because an operator needs to
simultaneously manipulate the joysticks of the respective work devices with skill
according to each task, a high level of operating skill is required. Because the conditions
at excavating sites are very poor and dangerous, there is an increasing need for research
for intelligent excavators that are controlled automatically using predetermined control
algorithms instead of being operated manually by an operator. That is, there is a
need for an automated excavating solution that can be easily implemented by even an
inexperienced operator.
[0005] By automatically performing simple repetitive excavating tasks without a human operator,
an intelligent excavator may help to reduce labor costs and reduce the risk of accidents.
As part of this scheme, in order for an operator to perform automated excavation work,
it is necessary to receive information on the excavating conditions in real time through
various sensors.
[0006] In order for an operator to perform various tasks with an excavator, because the
operator needs to simultaneously manipulate the joysticks of the respective work devices
with skill according to each task, a high level of operating skill is required.
[0007] In particular, when performing the same task repetitively, because an operator repeats
the same manipulations with a high level of skill, this requires concentration over
the course of many hours, which can reduce work efficiency. There is also the problem
of having to perform the same task again when a faulty manipulation of the joystick
by an inexperienced operator causes equipment to greatly deviate from a certain trajectory.
There is thus a great need for a trajectory controlling technology for repetitively
performing the same task in a reliable manner, while actively performing management
according to excavating conditions, repetitively setting the same task, and automatically
and repetitively performing the task.
[Disclosure]
[Technical Problem]
[0008] The present invetion is made to solve the problems, and an object of the present
invention is to provide a trajectory controlling device and method for construction
equipment, capable of automatically operating with the most suitable work trajectory
at the point when an automated task is selected.
[0009] That is, the obejct of the present invention is to provide a trajectory controlling
device and method for construction equipment, which employ a database and are capable
of performing an automated task in a work trajectory at a point after the posture
of a bucket that is not in a work trajectory of a selected point has been corrected,
in consideration of the current posture of the bucket, when automated excavation is
selected.
[0010] Another object of the present invention is to provide a apparatus and method for
controlling work trajectory of construction equipment, which use teaching and playback
to minimize positioning errors when an automated task is performed to follow a teaching
trajectory designated by an operator.
[Technical Solution]
[0011] In a first aspect of the present invention, there is provided a work trajectory controlling
device for construction equipment having at least one work device, and a driving unit
for driving the work device, the work trajectory controlling device including: an
actuating unit configured to generate a joystick signal through a manipulation by
an operator; a data storage unit configured to store driving trajectory data on the
work device, for the work device, to be driven upon starting of an automated task,
to follow; and a driving controller configured, upon the starting of the automated
task, to read trajectory data on the work device stored in the data storage unit,
and control the driving unit to drive the work device to follow the read driving trajectory
data, wherein when the automated task is selected, and an actual position of the work
device falls within a reference error range between a position at which driving of
the work device is started which is stored in the data storage unit, and a preset
position at which driving of the work device is started, the driving controller performs
controlling to start automated driving in a position at a time when the automated
task is selected and controls the driving unit to follow the prestored driving trajectory
over time while the automated driving is performed.
[0012] In a second aspect of the present invention, there is provided a work trajectory
controlling method for construction equipment having at least one work device, a driving
unit configured to drive the work device, and an actuating unit configured to generate
a joystick signal through a manipulation by an operator, the method including: checking
whether an automated task is selected; and when the automated task is selected, comparing
an actual position of the work device with a preset automated task starting position,
and comparing a difference thereof with a preset reference error, wherein when results
of the comparison show that a difference between the actual position of the work device
and the preset automated task starting position is less than the reference error,
preset trajectory data on the work device is read, and trajectory data is generated
for an automated task starting at the actual position of the work device, after which
the automated task is started, and the new trajectory data is generated to follow
the preset trajectory data of the work device as time elapses.
[Advantageous Effects]
[0013] According to the present invention, automated work is possible based on the current
posture of a work device when an automated task is selected, and it is possible to
prevent the automated task from being performed inefficiently due to an improper posture
of the work device when the automated task is begun.
[0014] Moreover, work may be easily performed even by an inexperienced operator, through
an automated task selection function.
[0015] Also, according to the present invention, when playback is selected to follow a teaching
trajectory, a positioning error is compensated for to enable a work device to be driven
in a trajectory desired by an operator.
[0016] Further, even when the position of a work device at the time playback is selected
is different from a starting point of a teaching trajectory learned by an operator,
the operator may perform work within desired work parameters in a short time when
the difference is not great.
[0017] In addition, changes related to gravity brought about by changes in the posture of
a work device may be compensated for in order to minimize positioning errors.
[Description of Drawings]
[0018]
FIG. 1 is a configurative diagram of a work trajectory controlling device for construction
equipment according to an exemplary embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of using a database to control the work
trajectory of construction equipment according to an exemplary embodiment of the present
invention.
FIG. 3 is a detailed configurative diagram of a work trajectory controlling device
in playback mode according to an exemplary embodiment of the present invention.
FIG. 4 is a flowchart of a method for controlling a work trajectory of construction
equipment by using a database according to an exemplary embodiment of the present
invention.
FIG. 5 is a flowchart of a method for controlling a work trajectory in teaching mode
according to an exemplary embodiment of the present invention.
FIG. 6 is a flowchart of a method for controlling a work trajectory in playback mode
according to an exemplary embodiment of the present invention.
[Description of Main Reference Numerals of Drawings]
[0019]
100: |
Work trajectory controlling device |
110: |
Actuating unit |
120: |
Driving controller |
130: |
Gravity compensating unit |
140: |
Driving unit |
150: |
Data storage unit |
[Mode for Carrying Out the Invention]
[0020] Hereinafter, exemplary embodiments of the present invention will be described in
detail with reference to the accompanying drawings. The structure of the present invention
and the effects derived therefrom will be clearly understood through the detailed
description below. Before providing the detailed description of the present invention,
it should be noted that the same components are identified by the same reference numerals
whenever possible even in different drawings, and when it is determined that detailed
description relating to well-known functions or configurations may make the subject
matter of the present invention unnecessarily ambiguous, the detailed description
will be omitted.
[0021] FIG. 1 is a configurative diagram of a work trajectory controlling device for construction
equipment according to an exemplary embodiment of the present invention.
[0022] As illustrated in FIG. 1, a work trajectory controlling device 100 according to the
present invention includes an actuating unit 110, a driving controller 120, a gravity
compensating unit 130, a driving unit 140, and a data storage unit 150. Here, the
work trajectory controlling device 100 controls the work trajectory of construction
equipment, and includes at least one work device, and the driving unit 140 for driving
the work device. When performing an automated task with the work trajectory controlling
device for construction equipment according to the present invention, the position
of a work device is described in terms of having a large positioning error or a small
positioning error with respect to a preset reference value, and a case in which a
work trajectory controlling device for construction equipment operates using a database
and a case in which a work trajectory controlling device for construction equipment
operates using teaching and playback are described. Also, an example of applying the
present invention to an excavator among the work devices will be described.
[0023] First, a description will be provided starting with a work trajectory controlling
device for construction equipment using a database according to the present invention.
[0024] Preset driving trajectory data for a work device is stored in the data storage unit
150, in order for an automated task to be started at a position corresponding to any
of the positions of the work device. That is, the data storage unit 150 builds and
stores a database with driving trajectory data for each set of position coordinates
for the end of the excavator bucket. Here, the driving trajectory data includes joystick
data and cylinder length data, or angle data on each link of the boom, the arm, and
the bucket. In the present exemplary embodiment, the above-described driving trajectory
data is described in terms of the position of the bucket, as an example. However,
the present invention is not necessarily limited thereto, and trajectory data may
be formed on the basis of the boom, the arm, and various other work devices. However,
when the bucket forms the basis for the trajectory data as in the present exemplary
embodiment, because the moving trajectory of the bucket that directly contacts the
surface that is actually worked is very similar to the work parameters intended by
the operator, it may be preferable to perform controlling with the position of the
bucket at the center, as in the present exemplary embodiment.
[0025] To describe the driving trajectory data of the excavator, the data storage unit 150
stores driving trajectory data for each set of position coordinates that may begin
at position coordinates of the end of the excavator bucket as a reference, and may
include driving trajectory data from all points on which the end of the bucket may
be disposed. Also, the driving trajectory data is made and stored as a database, in
terms of the desirable bucket angles for performing tasks. At the time the excavator
is delivered, driving trajectory data related to excavating at all points may be compiled
in a database. Such driving trajectory data based on position may be set through the
following example. First, the range over which the end of the bucket is driven for
a task is divided into ranges of predetermined sizes. Excavating, flattening, trenching,
and other tasks are predicted to respectively be performed from where the end of the
bucket is disposed at the center of each range, and trajectory data based thereon
is prestored.
[0026] Based on manipulations by an operator, the actuating unit 110 outputs information
on whether automated task start has been selected and position information on the
work device at the time when the automated task is started to the driving controller
120. Here, the actuating unit 110 may include a joystick or an automated task start
button, or the like. In this case, a joystick signal, an automated task button signal,
or the like is output according to the manipulations of the operator.
[0027] When an automated task is selected, the driving controller 120 reads driving trajectory
data corresponding to the current position of the work device from the data storage
unit 150, and controls the driving unit 140 to drive the work device to follow the
driving trajectory data read from the data storage unit 150.
[0028] That is, when the automated task is selected, the driving controller 120 checks the
posture of the work device. When the checked results show that the posture of the
work device is a posture with which a designated task cannot be performed immediately,
the driving controller 120 controls the driving unit 140 so that the work device is
changed in posture so as to be capable of performing the designated task. Conversely,
when it is found that the posture of the work device is a posture allowing the designated
task to be performed immediately, the driving controller 120 checks whether the new
position of the work device brought about by the change in posture will be largely
different from a preset reference value.
[0029] Next, when the checked results for the reference value show that the new position
will differ largely from the preset reference value, the driving controller 120 reads
new driving trajectory data corresponding to a new position changed by a change in
the posture of the bucket from the data storage unit 150, and then controls the driving
unit 140 so that the work device is driven to follow the new driving trajectory data.
Conversely, when the checked results for the reference value show that the new position
will not differ largely from the preset reference value, the driving controller 120
controls the driving unit 140 so that the work device is driven to follow driving
trajectory data corresponding to the initially selected position.
[0030] To describe an excavator equipped with a bucket from among work devices as an example,
the driving controller 120 checks the posture of the bucket when an automated task
is started. When the checked results show that the posture of the bucket is similar
to a reference posture, the driving unit 140 is controlled so that driving trajectory
data will be followed at the time of an operator's selection. Conversely, when the
posture of the bucket differs largely from the reference posture, the driving controller
120 changes the posture of the bucket. The driving controller 120 changes the angle
of bucket to a reference bucket angle at the time of the operator's selection, in
consideration of the current bucket angle.
[0031] Also, the driving controller 120 checks for a position change brought about by a
change in the posture of the bucket. Here, the excavator includes the bucket, and
the driving controller 120 determines whether there is a change in the posture of
the excavator based on the posture of the bucket. When the checked position change
results show that there is no large change in position, the driving controller 120
controls the driving unit 140 so that the initially selected trajectory data is ultimately
followed. Conversely, when there is a large change in position, the driving controller
120 reads new driving trajectory data corresponding to the changed position from the
data storage unit 150, and then controls the driving unit 140 so that the new driving
trajectory data is followed. Here, whether or not the new driving trajectory data
is to be read is selected based on a position change of the bucket corresponding to
a change in the posture of the bucket.
[0032] In this case, the driving controller 120 has various sensors so that when it is sensed
that a change in the posture of the bucket will be impeded by an obstacle such as
a ground surface, the posture of the bucket may be changed by automatically driving
other work devices such as the boom/arm in an optimized trajectory.
[0033] To describe in detail a case in which the bucket angle is preset at 10° by the work
trajectory controlling device 100, during automated excavating, the driving controller
120 compares a preset bucket angle (for example, 10°) to the current bucket angle,
and controls the driving unit 140 to move the bucket cylinder when the current bucket
angle exceeds the preset angle, so that the bucket angle falls within the preset angle.
If it is determined that the bucket is stuck on the ground surface or in a difficult-to-drive
situation, the driving controller 120 controls the driving unit 140 to actuate the
cylinders of the boom, arm, and bucket together in order to set the bucket angle in
order to set the bucket angle.
[0034] If the position of the end of the bucket is changed after the bucket angle is set,
the driving controller 120 reads new driving trajectory data for the changed position
from the data storage unit 150.
[0035] Then, in order to perform an automated excavating task, the driving controller 120
may control a task starting point and the following of a trajectory so as to compensate
for a positioning error based on driving trajectory data stored in the data storage
unit 150, and may compensate for changes related to gravity brought about by posture
changes, in order to minimize positioning errors for the end of the bucket of the
excavator and control the driving of the excavator. Here, the driving controller 120
may apply a gravity compensating value, calculated by the gravity compensating unit
130, for drive control. Length data for each cylinder of the excavator may be substituted
with angle data on each link of the boom, arm, and bucket. Here, when a new joystick
signal is generated for a predetermined time from the actuating unit 110 during an
automated task, the driving controller 120 controls the driving unit 140 to stop the
automated task and follow the new joystick signal that is generated.
[0036] During automated excavating, the driving controller 120 obtainsdriving trajectory
data (for example, joystick data (Joy_ref data) and cylinder length data (Cyl_ref
data)) that is stored in the data storage unit 150. Also, the driving controller 120
adds a joystick signal (O_Joy), a positioning error signal (O_PI1), and a gravity
compensating signal value (Ga), and outputs a drive control signal (Com_out) to the
driving unit 140.
[0037] To describe in detail the outputting process of the drive control signal (Com_out),
the driving controller 120 obtains a joystick signal (O_Joy) from joystick data (Joy_ref
data). Also, the driving controller 120 subtracts a cylinder length signal and a current
measured signal from the cylinder length data (Cyl_ref data) to obtain an error signal
(Er). In addition, the driving controller 120 uses the error signal (Er) to calculate
a positioning error signal (O_PI1) through a PI controller.
[0038] The gravity compensating unit 130 obtains a mass inertia moment through a current
posture change of the excavator and calculates a gravity compensating value (Ga).
This is to minimize a positioning error for the end of the bucket caused by a posture
change of the excavator.
[0039] When the gravity compensating value (Ga) is determined, the driving controller 120
calculates a driving output value (O_joy+O_PI1+Ga) which is the sum of the joystick
signal (O_Joy), the positioning error signal (O_PI1), and the gravity compensating
value (Ga). Also, the driving controller 120 converts the added driving output value
(O_joy+O_PI1+Ga) to a drive control signal (Com_out) to output to the driving unit
140.
[0040] If a new joystick signal is generated by the actuating unit 110 for a preset time
(for example, 0.3 sec) during automated excavation, the driving controller 120 assumes
an emergency situation and controls the driving unit 140 to stop the automated task
and follow the joystick signal generated by the actuating unit 110.
[0041] FIG. 2 is a diagram illustrating an example of using a database to control the work
trajectory of construction equipment according to an exemplary embodiment of the present
invention.
[0042] As illustrated in FIG. 2, the data storage unit 150 forms a database with driving
trajectory data at coordinates (211) at which the end of the bucket is disposed, and
stores the database. The data storage unit 150 designates a bucket position at which
excavation is possible as a position coordinate value, and stores driving trajectory
data corresponding to the designated position coordinate value as a database. Here,
all position coordinates 210 are represented by (0, 0) to (x, y) in the database.
Here, x and y are position coordinates representing positions at which excavation
is possible in a basic length unit. For example, x and y represent the maximum position
coordinates, at which an excavating task is possible within the range in which the
excavator operates.
[0043] The data storage unit 150 stores driving trajectory data on the position coordinates
211 at a selected point. When the driving controller 120 requests driving trajectory
data on the position coordinates 211, the data storage unit 150 relays driving trajectory
data on the position coordinates 211 to the driving controller 120. Here, the driving
trajectory data may include joystick data and cylinder length data, or angle data
on each link of the boom, arm, and bucket, relayed from the driving controller 120.
[0044] A detailed description of each element will be provided for the case where the work
trajectory controlling device 100 for construction equipment illustrated in FIG. 1
according to the present invention operates as a work trajectory controlling device
for construction equipment using teaching and playback.
[0045] The present invention relates to a apparatus and method for controlling work trajectory
of construction equipment which are capable of minimizing positioning errors when
playback is selected, whereby an operator rides a work device (for example, an excavator
and a wheel loader) and a trajectory for performing a certain task is stored in the
work device (this task is hereinafter referred to as "teaching"), and the stored trajectory
(for example, for the position of the end of a bucket) is followed to drive the work
device automatically. Below, an excavator will be described as an example of a work
device to which the present invention is applied.
[0046] The work trajectory controlling device 100 is operated in teaching mode or in playback
mode. Here, the actuating unit 110 generates a joystick signal through manipulation
by an operator, and the operator may select and actuate teaching mode and playback
mode.
[0047] First, teaching mode denotes a mode in which an operator teaches a task process of
an excavator. When the operator manipulates a joystick in teaching mode, the work
trajectory controlling device 100 stores the joystick signal according to the joystick
manipulation and each piece of cylinder length data (hereinafter referred to as "driving
data") of the driving unit 140. Here, the operator may start or end teaching mode
through a teaching start and end button, and the like provided on the actuating unit
110 of the excavator.
[0048] To specifically describe teaching mode, while operating in teaching mode, the actuating
unit 110 transfers joystick signals generated according to the manipulation of the
joystick by the operator to the driving controller 120. Here, the driving controller
120 receives the joystick signals from the actuating unit 110 and controls the driving
of the driving unit 140. Also, when teaching mode is selected, the driving controller
120 processes driving data on the work device and the joystick signals corresponding
to the manipulations of the operator, and stores generated trajectory data in the
data storage unit 150. That is, the driving controller 120 stores the joystick signals
transferred from the actuating unit 110 as joystick data in the data storage unit
150. Also, the driving controller 120 stores cylinder length data of the boom, arm,
and bucket driven by the driving unit 140, or angle data for each link in the boom,
arm, and bucket in the data storage unit 150.
[0049] The driving unit 140 drives the cylinders of the boom, arm, and bucket according
to the drive control of the driving controller 120.
[0050] Second, the playback mode denotes a mode in which the work trajectory controlling
device 100 automatically plays back the task process stored in the teaching mode.
[0051] The data storage unit 150 stores trajectory data (for example, joystick data and
data on the length of each cylinder) taught in teaching mode. Also, the data storage
unit 150 may store joystick data and angle data for each link of the boom, arm, and
bucket as trajectory data.
[0052] When playback mode is selected, the driving controller 120 controls the driving unit
140 to automatically drive the work device to follow trajectory data stored in the
data storage unit 150 in teaching mode. First, the position of the work device is
compared to a starting position of the work device stored in the data storage unit
150 at the point when playback mode is selected. When the results of the comparison
show that the positions are within a preset reference error range, the driving controller
120 performs controlling to start automated driving at the position at which playback
mode is selected. Any of the work devices may be used to measure the positioning error
range. For performing a task such as excavation, the present exemplary embodiment
describes an example of a controlling method that sets the position of the bucket,
which directly contacts the surface to be worked and can be said to be central to
the task, as the basis for performing controlling. That is, a positional difference
is determined between the current position of the end of the bucket and a preset initial
position of the end of the bucket, so that the control of playback mode is made possible.
Here, the driving controller 120 controls the driving unit 140 to follow a preset
driving trajectory as the time elapses in which automated driving is performed. This
is to enable a task to be performed within an initially input working range as time
elapses, even when automated driving is started at a point not desired by an operator.
The driving controller 120 compensates for a positioning error with respect to the
trajectory data stored in the data storage unit 150, while automated driving of the
work device is performed. In order to minimize a positioning error for the end of
the bucket of the excavator in the present exemplary embodiment, the driving of the
excavator is controlled by compensating for the effects of gravity corresponding to
the posture of the work device. Here, the driving controller 120 applies a gravity
compensating value calculated by the gravity compensating unit 130 and updates trajectory
data, and controls the driving unit 140 on the basis of the updated trajectory data.
Data on the length of each cylinder of the excavator from trajectory data may be substituted
with angle data on each link of the boom, arm, and bucket. The gravity compensating
unit 130 obtains a mass inertia moment through a change in the current posture of
the excavator and calculates a gravity compensating value. This is to minimize a positioning
error for the end of the bucket brought about by a change in posture of the excavator.
These gravity compensating results are used to compensate for the flow discharged
from a pump or the degree to which a control valve has been switched, and thus enables
the driving speed of the work device initially intended by the operator to be followed.
The system may be configured to enable the operator to perform controlling through
playback start and end buttons, and the like provided on the actuating unit 110 for
starting/ending the playback mode.
[0053] The controlling method above is described as an example in which the operator needs
to move the work device back to the initial position for the desired task when desiring
to reuse playback mode after playback mode is ended. However, the above-described
playback mode is not necessarily limited thereto. That is, an application may be possible
in which playback mode is selected to automatically repeat. When playback mode is
thus automatically repeated, as described above, controlling is possible where a portion
where a task could not be performed when playback mode is initially started may be
automatically redone. This may be accomplished by performing playback mode again after
the work device is automatically moved to the initial position for the task which
is automatically stored in teaching mode, when being repeated a second time. Accordingly,
even when playback is started with the work device in an inaccurate position through
the inexperienced performing of a task, the area intended to be worked by the operator
may be worked by repeating the task.
[0054] When the positioning error at the time playback mode is started is greater than a
preset reference error, a notification may be issued that playback mode cannot be
started because automated work is not possible in a work area intended by the operator,
and the system may wait for an actuating signal to be input again by the operator.
Conversely, in order to enable the work device to work actively, when the above-described
positioning error is greater than the reference error, the method may be used of automatically
controlling each work device so that the work device (more particularly, the bucket)
is positioned at the playback mode starting point stored in teaching mode.
[0055] In the above playback mode state, when a new joystick signal is generated through
an operator from the actuating unit 110 for a predetermined time, the driving controller
120 may stop playback mode and control the driving unit 140 according to the new joystick
signal generated from the actuating unit 110, in anticipation of a similarity.
[0056] FIG. 3 is a detailed configurative diagram of a work trajectory controlling device
in playback mode according to an exemplary embodiment of the present invention.
[0057] When the playback button is selected, the driving controller 120 performs controlling
to estimate the task starting point and trajectory in order to compensate for the
positioning error of the bucket, and minimizes the error to compensate for the effects
of gravity brought about by a change in the posture of the work device.
[0058] That is, at the start of playback, the driving controller 120 includes the processes
of measuring the distance between the current position of the end of the bucket and
the position of the end of the bucket when teaching mode is started, and of comparing
a value of the difference between the current position of the end of the bucket and
a preset initial position of the end of the bucket with a preset reference error (for
example, 10 cm). This takes into account that when a playback task is begun after
an ordinary operator positions a work device at an intended position, and the playback
task is started, the posture/position of the work device at the time playback is started
can only be different from a prestored playback initial position. As described above,
when the difference value with the initial position is less than the reference error,
and playback is started, the work device is operated directly at the position selected
through the manipulation of the operator and is controlled to keep close to the taught
driving trajectory as time passes. In this case, a portion of the work area intended
by the operator at the start of playback may not have been worked, and in this case
when playback is repeatedly performed, the work device is automatically positioned
at the taught initial position for the next session of playback work, to thereby solve
the problem of the unworked area. When there is a large difference between the posture/position
of the work device at the start of playback and a prestored playback initial position,
a method may be used for indicating that playback work is not possible and waiting
for a further manipulation by the operator, or for automatically positioning the work
device to the playback initial position and then performing work by following a taught
trajectory. The present exemplary embodiment is described as an example of moving
the work device and then performing playback work.
[0059] After the start of playback, the driving controller 120 receives pre-taught joystick
data (Joy_ref data) and cylinder length data (Cyl_ref data). Also, the driving controller
120 adds a joystick signal (O_Joy), a positioning error signal (O_PI1), and a gravity
compensating value (Ga), and outputs a drive controlling signal (Com_out) to the driving
unit 140.
[0060] To describe the process of outputting the drive controlling signal (Com_out) in detail,
the driving controller 120 receives the joystick signal (O_Joy) from the joystick
data (Joy_ref data). Also, the driving controller 120 deducts a cylinder length signal
and a currenly measured signal from the cylinder length data (Cyl_ref data) to obtain
an error signal (Er). The driving controller 120 also calculates a positioning error
signal (O_PI1) from the error signal (Er) through a PI controller.
[0061] The gravity compensating unit 130 calculates the gravity compensating value (Ga)
by obtaining a mass inertia moment from the current posture of the work device.
[0062] When the gravity compensating value (Ga) is determined, the driving controller 120
calculates a driving output value (O_joy+O_PI1+Ga) which is the sum of the joystick
signal (O_Joy), the positioning error signal (O_PI1), and the gravity compensating
value (Ga). Also, the driving controller 120 converts the summed driving output value
(O_joy+O_PI1+Ga) to a drive controlling signal (Com_out) to output to the driving
unit 140.
[0063] When a joystick signal is generated by the actuating unit 110 for a preset time (for
example, 0.3 sec) or more during playback, the driving controller 120 assumes an emergency
situation and controls the driving of the driving unit 140 according to the joystick
signal generated by the actuating unit 110.
[0064] The method for controlling the work trajectory of construction equipment according
to the present invention will be described as divided into a work trajectory controlling
method for construction equipment using a database, and a work trajectory controlling
method in teaching mode. First, a work trajectory controlling method for construction
equipment using a database will be described.
[0065] FIG. 4 is a flowchart of a method for controlling the work trajectory of construction
equipment by using a database according to an exemplary embodiment of the present
invention.
[0066] First, to describe the process of selecting an automated task for the work device,
an operator positions the work device at a desired position through a joystick and
the like provided on the actuating unit 110. Then, when the operator selects an automated
task start through an automated task selecting button and the like provided on the
actuating unit 110, the automated task for the work device is selected.
[0067] After the selection of the automated task, the work trajectory controlling device
100 calculates the current position of the bucket and receives driving trajectory
data at those position coordinates from the database (DB) in step 402.
[0068] The work trajectory controlling device 100 also compares the current posture of the
bucket with a preset reference posture, and checks whether a difference between a
current bucket angle at the current bucket position and a bucket angle in the database
exceeds a certain angle (for example, 10°) in step 404.
[0069] According to the results of the comparison, the work trajectory controlling device
100 changes the posture of the work device to the reference posture.
[0070] To describe the process of change to the reference posture in detail, when the results
of the check in step 404 show that the difference between the current bucket angle
and the initial bucket angle exceeds the certain angle, the work trajectory controlling
device 100 moves the current bucket angle to the initial bucket angle in step 406.
Here, the initial bucket angle may be preset as a bucket angle that is preferable
to perform an excavating task or may be set by the operator. If the bucket is stuck
on the ground surface or is in a difficult-to-drive state, the work trajectory controlling
device 100 may actuate the cylinders of the boom, arm, and bucket to move the bucket,
in order to set the bucket angle. This state in which the bucket cannot be moved can
be determined by sensing changes in the hydraulic pressure and changes in posture
of each work device, and in the present exemplary embodiment, various sensors are
installed on each hydraulic line and joint portions for that purpose.
[0071] The work trajectory controlling device 100 receives trajectory data corresponding
to a change in position of the work device according to a change in posture from the
database, and controls the driving of the work device so that the work device is automatically
driven to follow the read trajectory data.
[0072] That is, when the current bucket is moved to an initial bucket angle, and then the
position of the end of the bucket is changed, the work trajectory controlling device
100 calculates the changed position of the bucket and receives driving trajectory
data on the position coordinates at which the end of the bucket is positioned from
the database in step 408.
[0073] Conversely, when the checked results in step 404 show that the difference between
the current bucket angle and the initial bucket angle is below a certain angle, the
work trajectory controlling device 100 performs step 410 onward.
[0074] Then, the work trajectory controlling device 100 starts automated excavation in step
410 by using the driving trajectory data on the current position according to the
received database in steps 402 or 408.
[0075] The work trajectory controlling device 100 outputs joystick signals, which are stored
at 10ms intervals, every 10ms in step 412.
[0076] Also, the work trajectory controlling device 100 calculates an error (Er=Cyl_ref-Cyl_cur)
between cylinder length data (Cyl_ref) stored for each cylinder and currently measured
data (Cyl_cur) in step 414.
[0077] Subsequently, the work trajectory controlling device 100 checks whether the error
between the cylinder length for even one of three cylinders, from the cylinder lengths
stored for each cylinder, and the currently measured cylinder length is a preset cylinder
length error value (for example, 5cm) or greater in step 416.
[0078] When the checked results in step 416 show that the error between the reference cylinder
length and the currently measured cylinder length is greater than the preset cylinder
length error value (for example, 5cm), the work trajectory controlling device 100
shows the operator a message that the task cannot be performed and ends trajectory
control in step 418.
[0079] Conversely, when the checked results in step 416 show that the error between the
reference cylinder length and the currently measured cylinder length is below the
preset cylinder length error value (for example, 5cm), the work trajectory controlling
device 100 calculates a positioning error signal (O_PI1=Kp*Er+Ki*sum(Er)) to perform
feedback control through a proportional integral (PI) controller in step 420.
[0080] Next, in step 422, the work trajectory controlling device 100 calculates a compensating
value (Ga) by obtaining a mass inertia moment from the current posture of the work
device, and obtains a PI controlling signal (O_PI=O_PI1+Ga) to which gravity compensation
has been applied according to the positioning error signal (O_PI1) calculated in step
420, and posture. For example, because the boom, arm, and bucket of an excavator are
heavy, the pressures required to move the boom, arm, and bucket are different when
they are all spread out and when they are all converged. Therefore, the work trajectory
controlling device 100 compensates for when the effects of gravity on the boom, arm,
and bucket are different, so as to perform fast and accurate control. That is, when
the boom, arm, and bucket are spread out, the work trajectory controlling device 100
adds a gravity compensating value (Ga) corresponding to a gravity compensation to
the positioning error signal (O_PI1) calculated in step 420 so that a greater output
can be generated.
[0081] The work trajectory controlling device 100 also calculates a driving output value
(O_co=Ojoy+O_PI1+Ga) as a final output in step 424 by adding the joystick output signal
(O_joy) received in step 412, the positioning error signal (O_PI1) from step 420,
and the PI controlling signal (O_PI) calculated in step 422.
[0082] The work trajectory controlling device 100 checks in step 426 whether an executing
length matches a buffer length stored in the data storage unit 150.
[0083] When the results of the checking in step 426 show that the executing length does
not match the buffer length, the work trajectory controlling device 100 outputs the
driving output value calculated in step 424 and performs the steps again from step
412. Conversely, when the executing length and the buffer length match, the work trajectory
controlling device 100 ends trajectory control together with a task completed message.
[0084] If, during work trajectory control, a new joystick signal is generated by the operator
for a preset time (for example, 0.3 sec), the work trajectory controlling device 100
may assume an emergency situation, and end the automated task and control the work
device according to the new joystick signal.
[0085] A work trajectory controlling method in teaching mode will be described from among
work trajectory controlling methods for construction equipment using teaching and
playback according to the present invention.
[0086] FIG. 5 is a flowchart of a method for controlling a work trajectory in teaching mode
according to an exemplary embodiment of the present invention.
[0087] The work trajectory controlling method according to the present invention is applied
to a work trajectory controlling device 100 for construction equipment that includes
at least one work device, a driving unit 140 for driving the work device, and an actuating
unit 110 for generating a joystick signal corresponding to a manipulation by an operator,
and is capable of selective operation in teaching mode and playback mode.
[0088] The work trajectory controlling device 100 checks in step 502 whether a start button
signal for indicating teaching start has been input by an operator.
[0089] When teaching mode is selected, the work trajectory controlling device 100 stores
the joystick signal generated by the manipulation of the operator and the driving
data of the work device as trajectory data. That is, when the checked results in step
502 show that the start button is input, after the start button signal, the work trajectory
controlling device 100 stores an angle at which the joystick is moved by the operator
in preset time intervals (for example, 10ms), and senses and stores the cylinder length
for each of the boom, arm, and bucket in step 504. For example, the work trajectory
controlling device 100 may store the joystick angle and cylinder length at 10ms intervals.
The work trajectory controlling device 100 may also sense and store the angles of
each link of the boom, arm, and bucket. Here, the work trajectory controlling device
100 may calculate the cylinder length or angles of each link of the boom, arm, and
bucket in order to mechanically calculate the position of the end of the bucket. Conversely,
when the checked results in step 502 show that the start button signal is not input,
the work trajectory controlling device 100 continuously monitors whether the start
button signal is input.
[0090] Then, the work trajectory controlling device 100 checks in step 506 whether an end
button signal indicating the end of teaching is input.
[0091] When the checked results in step 506 show that the end button signal is input, the
work trajectory controlling device 100 stores the joystick angles and cylinder lengths
of the boom, arm, and bucket stored until the present as one piece of trajectory data.
Conversely, when the end button signal is not input, the work trajectory controlling
device 100 performs the steps again from 504, in which trajectory data is stored.
[0092] FIG. 6 is a flowchart of a method for controlling a work trajectory in playback mode
according to an exemplary embodiment of the present invention.
[0093] The work trajectory controlling device 100 checks in step 602 whether a playback
start button signal, indicating that playback is started by an operator, is input.
[0094] When the checked results in step 602 show that the playback start button signal is
input by the operator, the work trajectory controlling device 100 measures the distance
between the current position of the end of the bucket and the position of the end
of the bucket when teaching is started, and checks whether a difference value between
the current position of the end of the bucket and a preset initial position of the
end of the bucket exceeds a preset reference error (for example, 10cm) in step 604.
Conversely, when the playback start button signal is not input by the operator, the
work trajectory controlling device 100 performs step 602 onward until the playback
start button signal is input.
[0095] When the checked results in step 604 show that the position difference value between
the current position and the initial position of the end of the bucket exceeds the
preset reference error, the work trajectory controlling device 100 controls the bucket
to move the current position of the end of the bucket to the preset initial position
in step 606. The work trajectory controlling device 100 controls each actuator to
move the bucket so that the position of the end of the bucket is within 10cm of the
position difference value. Here, when a selection is made so that an automated task
is repeatedly performed through playback mode selection when the position difference
is greater than the reference error, the work trajectory controlling device 100 performs
controlling so that the automated task is performed after the work device is returned
to the position at which teaching mode is started after the automated task is first
performed.
[0096] Conversely, when the checked results in step 604 show that the position difference
value between the current position and the initial position of the end of the bucket
is less than the preset reference error - that is, the position of the end of the
bucket is within 10cm, the work trajectory controlling device 100 outputs a playback
signal every 10ms in order to automatically drive the work device at the current position,
and uses the signal as a reference playback signal. Here, even when there is a difference
between the initial position and the teachingposition of the work device when a position
compensating method as described below is used, when the playback task is performed,
data is compensated for so as to follow a taught trajectory within the shortest time
possible and is used for driving the work device.
[0097] In more detail, the work trajectory controlling device 100 receives a prestored joystick
signal (O_joy) every 10ms in step 608.
[0098] The work trajectory controlling device 100 also calculates an error (Er=Cyl_ref-Cyl_cur)
between cylinder length data (Cyl_ref) stored for each cylinder and currently measured
data (Cyl_cur) in step 610.
[0099] Next, the work trajectory controlling device 100 checks in step 612 whether the error
between the cylinder length for even one of three cylinders, from the cylinder lengths
stored for each cylinder, and the currently measured cylinder length is a preset cylinder
length error value (for example, 5cm) or greater.
[0100] When the checked results in step 612 show that the error between the reference cylinder
length and the currently measured cylinder length is the preset cylinder length error
value (for example, 5cm) or greater, the work trajectory controlling device 100 shows
the operator a message that the task cannot be performed and ends trajectory control
in step 614.
[0101] Conversely, when the checked results in step 612 show that the error between the
reference cylinder length and the currently measured cylinder length is below the
preset cylinder length error value (for example, 5cm), the work trajectory controlling
device 100 calculates a positioning error signal (O_PI1=Kp*Er+Ki*sum(Er)) in step
616 to perform feedback control through a proportional integral (PI) controller.
[0102] Next, in step 618, the work trajectory controlling device 100 calculates a compensating
value (Ga) by obtaining a mass inertia moment from the current posture, and obtains
a PI controlling signal (O_PI=O_PI1+Ga) to which gravity compensation has been applied
according to the positioning error signal (O_PI1) calculated in step 416, and posture.
For example, because the boom, arm, and bucket of an excavator are heavy, the pressures
required to move the boom, arm, and bucket are different when they are all spread
out and when they are all converged. Therefore, the work trajectory controlling device
100 compensates for when the effects of gravity on the boom, arm, and bucket are different,
so as to perform fast and accurate control. That is, when the boom, arm, and bucket
are spread out, the work trajectory controlling device 100 adds a gravity compensating
value (Ga) corresponding to a gravity compensation to the positioning error signal
(O_PI1) calculated in step 616 so that a greater output can be generated.
[0103] The work trajectory controlling device 100 also calculates a driving output value
(O_co=O_oy+O_PI1+Ga) as a final output in step 620 and controls the work device by
adding the joystick output signal (O_joy) received in step 608, the positioning error
signal (O_PI1) from step 616, and the PI controlling signal (O_PI) calculated in step
618. That is, the work trajectory controlling device 100 may calculate a gravity compensating
value by using a change in the effects of gravity brought about by a change in the
posture of the work device, and may apply the calculated gravity compensating value
to control the work device to follow a driving speed of the work device, which is
included in the trajectory data stored in teaching mode.
[0104] The work trajectory controlling device 100 checks in step 622 whether the executing
length matches a buffer length stored in the data storage unit 150.
[0105] When the results of the checking in step 622 show that the executing length does
not match the buffer length, the work trajectory controlling device 100 outputs the
driving output value calculated in step 622 and performs the steps again from step
408. Conversely, when the executing length and the buffer length match, the work trajectory
controlling device 100 ends trajectory control together with a task completed message.
[0106] As described above, the work trajectory controlling device 100 controls the operation
of a work device by following prestored trajectory data when playback mode is selected.
Here, the work trajectory controlling device 100 compares the position of the work
device at the point when playback mode is selected to the starting position when teaching
mode is started, and when the difference in positions is less than a preset reference
error, performs an automated task that follows the trajectory data at the selecting
point of playback mode selected by an operator, and performs controlling to follow
the stored trajectory data as time elapses.
[0107] If, during trajectory control, a joystick signal is input by a user for a preset
time (for example, 0.3 sec) or more, the work trajectory controlling device 100 assumes
an emergency situation and performs drive control according to the joystick signal.
[0108] As described above, although certain exemplary embodiments of the present invention
have been described in detail, it is to be understood by those skilled in the art
that the spirit and scope of the present invention are not limited to the certain
exemplary embodiments, but are intended to cover various modifications and changes
without departing from the subject matter of the present invention. Accordingly, the
exemplary embodiments disclosed in the specification of the present invention do not
limit the present invention in any way. The scope of the present invention is to be
defined by the scope of the appended claims below, and all technology that lies within
a similar scope shall be construed as falling within the scope of the present invention.
[Industrial Applicability]
[0109] The present invention is capable of performing an automated task using a work trajectory
at a point after the posture of a bucket that is not in a work trajectory at a selected
point has been corrected, in consideration of the current posture of the bucket, when
automated excavation is selected. Also, the present invention may control a task starting
point and the following of a trajectory to compensate for a positioning error when
playback is selected to follow a teaching trajectory, and may minimize positioning
errors by compensating for changes related to gravity due to changes in the posture
of a work device.
1. A work trajectory controlling device for construction equipment having at least one
work device, and a driving unit configured to drive the work device, the work trajectory
controlling device comprising:
an actuating unit configured to generate a joystick signal through a manipulation
by an operator;
a data storage unit configured to store driving trajectory data on the work device,
for the work device, to be driven upon starting of an automated task, to follow; and
a driving controller configured, upon the starting of the automated task, to read
trajectory data on the work device stored in the data storage unit, and control the
driving unit to drive the work device to follow the read driving trajectory data,
wherein when the automated task is selected, and an actual position of the work device
falls within a reference error range between a position at which driving of the work
device is started which is stored in the data storage unit, and a preset position
at which driving of the work device is started, the driving controller performs controlling
to start automated driving in a position at a time when the automated task is selected
and controls the driving unit to follow the prestored driving trajectory over time
while the automated driving is performed.
2. The device of claim 1, wherein the data storage unit stores driving trajectory data
on the work device to be driven for each position of the work device when the automated
task is performed; when the automated task is selected, and a posture of the work
device is a posture in which the work device is unable to immediately perform a designated
task, the driving controller performs controlling such that the work device is changed
to a posture in which to perform the designated task; and when a new position of the
work device brought about by the change in posture is greater than a preset reference
error for a preset position, the driving controller reads new driving trajectory data
corresponding to the new position and then controls the driving unit to drive the
work device to follow the new driving trajectory data.
3. The device of claim 2, wherein the work device includes a bucket, and the driving
controller determines whether a change has been made in a posture of the work device
based on a posture of the bucket and selects whether or not to read the new driving
trajectory data according to an amount of change in position of the bucket corresponding
to a change in the posture of the bucket.
4. The device of claim 1, wherein when the automated task is selected, and a posture
of the work device is a posture in which the work device is unable to immediately
perform a designated task, the driving controller performs controlling such that the
work device is changed to a posture in which to perform the designated task; and when
a new position of the work device brought about by the change in posture is greater
than a preset reference error for a preset position, the driving controller changes
a position of the work device to a position at which driving of the work device is
started, and then controls the driving unit to follow the prestored driving trajectory.
5. The device of any one of claims 1 to 4, wherein the work device includes a bucket,
and the driving controller reads the preset driving trajectory data on the work device
based on a position of the bucket.
6. The device of any one of claims 1 to 4, wherein when a new joystick signal is generated
from the actuating unit for a predetermined time during the performing of the automated
task, the driving controller ends the automated task and controls the driving unit
to follow the generated new joystick signal.
7. The device of any one of claims 1 to 4, wherein the driving controller further includes
a gravity compensating unit configured to calculate a gravity compensating value through
a posture of the work device.
8. The device of claim 1, wherein the actuating unit is capable of selecting and actuating
teaching mode and playback mode; and the driving controller stores the trajectory
data in the data storage unit in accordance with a manipulation by the operator, when
the teaching mode is selected, and controls the driving unit when the playback mode
is selected such that the work device is automatically driven to follow the trajectory
data of the work device stored in the data storage unit.
9. The device of claim 8, wherein when playback mode is selected by the operator, a current
position of an end of a bucket of the work device and a preset initial position of
the end of the bucket are compared in terms of a positional difference, and the driving
unit is controlled such that after the end of the bucket is moved to the preset initial
position, an automated task is performed to follow a prestored driving trajectory.
10. The device of claim 8 or 9, wherein when a new joystick signal is generated from the
actuating unit for a predetermined time during the performing of the automated task,
the driving controller ends the automated task and controls the driving unit to follow
the generated new joystick signal.
11. The device of claim 8 or 9, further comprising:
a gravity compensating unit configured to calculate a gravity compensating value corresponding
to a posture of the work device,
wherein the driving controller applies the gravity compensating value to update the
trajectory data, and controls the driving unit based on the updated trajectory data.
12. A work trajectory controlling method for construction equipment having at least one
work device, a driving unit configured to drive the work device, and an actuating
unit configured to generate a joystick signal through a manipulation by an operator,
the method comprising:
checking whether an automated task is selected; and
when the automated task is selected, comparing an actual position of the work device
with a preset automated task starting position, and comparing a difference thereof
with a preset reference error,
wherein when results of the comparison show that a difference between the actual position
of the work device and the preset automated task starting position is less than the
reference error, preset trajectory data on the work device is read, and trajectory
data is generated for an automated task starting at the actual position of the work
device, after which the automated task is started, and the new trajectory data is
generated to follow the preset trajectory data of the work device as time elapses.
13. The method of claim 12, wherein the comparing with the reference error includes:
a posture comparing step of comparing a current posture of at least one of a plurality
of work devices with a preset reference posture; and
a posture changing step of changing a posture of the work device to the reference
posture, according to results of the comparison, wherein
an actual position of the work device is revised to a changed position of the work
device according to the change in posture.
14. The method of claim 13, wherein the determining of a change in position of the work
device, after dividing a virtual range in which the work device is capable of being
driven for a task into a plurality of ranges, is based on whether to move the work
device from a range in which the work device is positioned initially to another range,
through a change in posture of the work device, and
the driving trajectory data are stored in the database to correspond to each of the
plurality of ranges.
15. The method of claim 14, wherein the construction equipment is capable of selecting
teaching mode and playback mode through a manipulation of an operator, and
the checking of whether the automated task is selected includes:
selecting the teaching mode for storing a joystick signal generated by a manipulation
of the operator and the driving data on the work device as trajectory data; and
selecting a playback step for selecting to start the automated task to follow the
trajectory data stored in the teaching mode selecting step.
16. The method of any one of claims 12 to 15, wherein in the trajectory playback step,
a gravity compensating value is calculated using a change in effects of gravity according
to a change in a posture of the work device, and the calculated gravity compensating
value is applied to control the work device to follow a driving speed of the work
device included in the trajectory data stored in the teaching mode.