Patent Description:
As a technology that enhances the work efficiency of a work machine (e.g. a hydraulic excavator) including a work implement (e.g. an articulated front work implement having a plurality of front implement members such as a boom, an arm, and a work tool (attachment)) driven by hydraulic actuators, there is machine control (Machine Control: MC). MC is a technology that assists operation performed by an operator by executing semi-automatic control of operating a work implement according to predetermined conditions when operation devices are operated by the operator.

Examples of MC include a technology of assisting an operator to form a current terrain profile into a desired profile. Regarding this technology, Patent Document <NUM> discloses a controller of a construction machine that determines a limited velocity of a boom from a limited velocity of an entire work implement, an arm target velocity, and a bucket target velocity while defining a distance of the blade tip of a bucket when it is positioned outside (above) a design surface as a positive value, and a velocity in a direction from the inner side (lower side) to the outer side (upper side) of the design surface (hereinafter, referred to also as a "target excavation surface") as a positive value, and controls the boom at the limited velocity of the boom and controls an arm at the arm target velocity when a first limitation condition including that the limited velocity of the boom is higher than a boom target velocity is satisfied.

In addition, as a different example of MC, there is a technology of preventing deviation of an excavator from a preset area (hereinafter, referred to also as a "work area"). In relation to this technology, Patent Document <NUM> discloses a technology of providing a dangerous area (hereinafter, referred to also as an "entry prohibited area") in an operation area space of a work implement (front work implement), decelerating a velocity of the work implement before the dangerous area, and stopping the work implement just before the dangerous area.

In Patent Document <NUM>, in order to prevent a bucket from moving into a design surface while a sense of discomfort felt by an operator is kept low, a limited velocity of a boom is calculated. Specifically, the limited velocity of the boom is calculated such that a vertical velocity generated by operation of all front implement members does not exceed a vertical limited velocity determined by a distance between the design surface and the bucket blade tip. At this time, vertical velocities of the arm and the bucket are velocities generated by operation by the operator. As a result, a sense of discomfort felt by the operator regarding operation at the time of excavation can be suppressed.

In Patent Document <NUM>, a deceleration area is provided before the dangerous area, and control is performed such that a work implement velocity generated by operator operation does not exceed an upper limit value defined in the deceleration area. Accordingly, an operator can concentrate on excavation work, and thus the burden on the operator at the time of excavator operation can be reduced.

On the other hand, at an actual site, there is a situation where both a design surface and a dangerous area are set. For example, when excavation is performed by using the technologies disclosed in Patent Document <NUM> and Patent Document <NUM> in a situation where there is a dangerous area below a design surface, there is a possibility that excavation along the design surface cannot be performed. For example, when excavation along a linear design surface is to be performed, it is necessary to cause a velocity vector. generated at the tip of a bucket by the combination of arm crowding operation and boom raising operation to point to a direction along the design surface. At this time, according to the control of Patent Document <NUM> (referred to as "excavation assistance control" in this document), a limited velocity of a boom for moving the bucket tip along the design surface is calculated with respect to the arm crowding operation according to operator operation. However, when the bucket tip enters a deceleration area, the control of Patent Document <NUM> (referred to as "deviation prevention control" in this document in some cases) is activated, and arm crowding operation actually generated is decelerated more than expected in the excavation assistance control, and thus the boom raising operation becomes excessive. Accordingly, the bucket tip floats above the design surface, and there is a fear that excavation operation along the design surface cannot be performed.

In addition, in some cases, there is also a situation where there is a dangerous area (e.g. a structure) above a design surface, and a work implement is positioned between the design surface and the dangerous area. When excavation is performed by using the technologies disclosed in Patent Document <NUM> and Patent Document <NUM> in such a situation, there is a possibility that a bucket enters the design surface. For example, if the deviation prevention control of Patent Document <NUM> is activated, and boom raising is decelerated or stopped because a rear end section of an arm approaches a dangerous area above the rear end section when linear excavation along a design surface is being performed by arm crowding operation and the boom raising operation according to the excavation assistance control of Patent Document <NUM>, there is a fear that the boom raising is insufficient for an amount expected in the excavation assistance control, a bucket tip enters the design surface, and excavation operation along the design surface cannot be performed.

As in these cases, in a situation where both a design surface (target excavation surface) and a dangerous area (a work area, an entry prohibited area) are set, there is a fear that the functionalities of the excavation assistance control of Patent Document <NUM>, and the deviation prevention control of Patent Document <NUM> interfere with each other.

In view of this, an object of the present invention is to provide a work machine that enables excavation along a target excavation surface even in a situation where a work implement is proximate to a work area boundary which is the boundary between a work area and a dangerous area (entry prohibited area) during excavation of the target excavation surface according to excavation assistance control. Note that, as mentioned above, deviation prevention control is control by which entry into the entry prohibited area is prevented, in other words, control by which deviation from the work area is prevented. In addition, the excavation assistance control is control by which a current terrain profile is formed into a profile defined by the desired target excavation surface.

The present invention is a work machine including: a work implement that is attached to a machine body, and has a plurality of front implement members including a work tool; a plurality of actuators that drive the machine body and the plurality of front implement members; an operation device that operates the plurality of actuators; a posture sensor that senses postural data about the machine body and the work implement; an operation sensor that senses operation data about the operation device; and a controller that is capable of controlling the work implement by using excavation assistance control of controlling the work implement such that the work tool moves along a predetermined target excavation surface and deviation prevention control of preventing deviation of the work implement from a predetermined work area by decelerating or stopping operation of a subject front implement member that is included in the plurality of front implement members and that can deviate the work implement from the work area, in which the controller is configured to control the work implement such that when the controller controls the work implement by using both the excavation assistance control and the deviation prevention control, an operation direction of the work tool approximates to an operation direction of the work tool that is to be generated when the work implement is controlled by using only the excavation assistance control.

According to the present invention, excavation along a target excavation surface becomes possible in a situation where a work machine is proximate to a work area boundary.

Hereinafter, embodiments of the present invention are explained by using the figures. Note that whereas the following illustrates, as a work machine, a hydraulic excavator including a bucket as a work tool (attachment) at the tip of a work implement (front work implement), the present invention may be applied to a work machine including an attachment other than a bucket. In addition, the present invention can also be applied to a work machine other than a hydraulic excavator as long as the work machine has an articulated work implement including a plurality of front implement members (a work tool, a boom, an arm, etc.) that are coupled with each other on a swingable structure.

In addition, in the following explanation, when there are a plurality of identical constituent elements, lowercase letters of the alphabet are given at the ends of reference characters in some cases, but the plurality of constituent elements are denoted collectively by omitting the lowercase letters of the alphabet in some cases. For example, when there are three identical pumps 190a, 190b, and 190c, these are denoted, collectively as pumps <NUM> in some cases.

In addition, a preset area where an excavator can work is referred to as a work area, and a boundary portion defining the work area is referred to as a work area boundary.

Note that in the embodiments depicted below, semi-automatic control, like the excavation assistance control and the deviation prevention control mentioned earlier, that operates a work implement according to predetermined conditions when operation devices are operated by an operator is collectively referred to as "MC.

<FIG> is a configuration diagram of a hydraulic excavator according to embodiments of the present invention, and <FIG> is a figure depicting a controller (controller) <NUM> of the hydraulic excavator according to the embodiments of the present invention along with a hydraulic drive system.

In <FIG>, a hydraulic excavator <NUM> includes an articulated front work implement (work implement) 1A and a body (machine body) 1B. The body (machine body). 1B includes a lower travel structure <NUM> that travels by using left and right travel hydraulic motors 3a and 3b, and an upper swing structure <NUM> that is attached on the lower travel structure <NUM>, is driven by a swing hydraulic motor <NUM>, and can swing in the leftward/rightward direction.

The front work implement 1A includes a plurality of front implement members (a boom <NUM>, an arm <NUM>, and a bucket (work tool) <NUM>) that are individually pivoted vertically, and are coupled with each other. front work implement 1A is attached to the upper swing structure <NUM> (machine body 1B). The base end of the boom <NUM> is pivotably supported at a front section of the upper swing structure <NUM> via a boom pin 8a (see <FIG>). The arm <NUM> is pivotably coupled at the tip of the boom <NUM> via an arm pin 9a, and the bucket <NUM> is pivotably coupled at the tip of the arm <NUM> via a bucket pin 10a. The boom <NUM> is driven by a boom cylinder <NUM>, the arm <NUM> is driven by an arm cylinder <NUM>, and the bucket <NUM> is driven by a bucket cylinder <NUM>.

In order to make it possible to measure pivot angles α, β, and γ (see <FIG>) of the boom <NUM>, the arm <NUM>, and the bucket <NUM>, a boom angle sensor <NUM> is attached to the boom pin 8a, an arm angle sensor <NUM> is attached to the arm pin 9a, a bucket angle sensor <NUM> is attached to a bucket link <NUM>, and a body inclination angle sensor <NUM> that senses an inclination angle θ (see <FIG>) of the upper swing structure <NUM> (body 1B) relative to a reference plane (e.g. a horizontal plane) is attached to the upper swing structure <NUM>. Note that each of the angle sensors <NUM>, <NUM>, and <NUM> can be replaced with an angle sensor (e.g. an inertial measurement unit (IMU: Inertial Measurement Unit)) that senses an angle relative to the reference plane (e.g. the horizontal plane). Alternatively, a cylinder stroke sensor that senses the stroke of each of the hydraulic cylinders <NUM>, <NUM>, and <NUM> may be used alternatively, and the obtained cylinder stroke may be converted into an angle. In addition, a swing angle sensor <NUM> that can sense a relative angle (swing angle θsw) between the upper swing structure <NUM> and the lower travel structure <NUM> is attached near the rotation center between the upper swing structure 12and the lower travel structure <NUM>. In addition, a swing-angular-velocity sensor <NUM> that can sense the angular velocity of a swing is attached to the upper swing structure <NUM>.

The five angle sensors <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are collectively referred to as a posture sensor <NUM> (see <FIG>) that senses postural data about the upper swing structure (machine body) <NUM> and the front work implement 1A, in some cases.

Operation devices that operate a plurality of the hydraulic actuators 3a, 3b, <NUM>, <NUM>, <NUM>, and <NUM> are installed in a cab provided on the upper swing structure <NUM>. Specifically, as the operation devices, a travel right lever 23a for operating the travel right hydraulic motor 3a (lower travel structure <NUM>), a travel left lever 23b for operating the travel left hydraulic motor 3b (lower travel structure <NUM>), an operation right lever 22a for operating the boom cylinder <NUM> (boom <NUM>) and the bucket cylinder <NUM> (bucket <NUM>), and an operation left lever 22b for operating the arm cylinder <NUM> (arm <NUM>) and the swing hydraulic motor <NUM> (upper swing structure <NUM>) are installed. Hereinbelow, these are collectively referred to as operation levers <NUM> and <NUM> in some cases.

An engine <NUM> which is a prime mover mounted on the upper swing structure <NUM> drives a hydraulic pump <NUM> and a pilot pump <NUM>. The hydraulic pump <NUM> is a variable displacement pump, and the pilot pump <NUM> is a fixed displacement pump.

In the present embodiment, the operation levers <NUM> and <NUM> are electric levers as depicted in <FIG>. , The controller <NUM> uses operation sensors (operator operation sensors) 52a to 52f such as rotary encoders or potentiometers to sense data (e.g. operation amounts and operation directions) about operation of the operation levers <NUM> and <NUM> by an operator, and sends electric current commands according to the sensed operation data to solenoid proportional valves 47a, 47b, 47c, 47d, 47e, 47f, <NUM>, <NUM>, 47i, 47j, <NUM>, and <NUM> (hereinafter, collectively referred to as solenoid proportional valves 47a-l in some cases). The solenoid proportional valves 47a-l are provided on a pilot line <NUM>, are driven when commands from the controller <NUM> are input thereto, output pilot pressures to flow control valves (control valves) <NUM>, and thereby drive the flow control valves <NUM>. The flow control valves <NUM> are configured to be able to supply a hydraulic fluid from the pump <NUM>. according to the operation data (the pilot pressures from the solenoid proportional valves 47a to 47f to the flow control valves <NUM>) about the operation levers <NUM> and <NUM> to each of the swing hydraulic motor <NUM>, the arm cylinder <NUM>, the boom cylinder <NUM>, the bucket cylinder <NUM>, the travel right hydraulic motor 3a, and the travel right hydraulic motor 3b. Note that the solenoid proportional valves 47a and 47b supply pilot pressures to flowcontrol valves <NUM> that supply the hydraulic fluid to the swing hydraulic motor <NUM>, the solenoid proportional valves 47c and 47d supply pilot pressures to flow control valves <NUM> that supply the hydraulic fluid to the arm cylinder <NUM>, the solenoid proportional valves 47e and 47f supply pilot pressures to flow control valves <NUM> that supply the hydraulic fluid to the boom cylinder <NUM>, the solenoid proportional valves <NUM> and <NUM> supply pilot pressures to flow control valves <NUM> that supply the hydraulic fluid to the bucket cylinder <NUM>, the solenoid proportional valves 47i and 47j supply pilot pressures to flow control valves <NUM> that supply the hydraulic fluid to the travel right hydraulic motor 3a, and the solenoid proportional valves <NUM> and <NUM> supply pilot pressures to flow control valves <NUM> that supply the hydraulic fluid to the travel right hydraulic motor 3b.

A lock valve <NUM> connected with the controller <NUM> is included between the pilot pump <NUM> and the solenoid proportional valves 47a-l on the pilot line <NUM>. A position sensor of a gate lock lever (not depicted) in the cab is connected with the controller <NUM>. When the gate lock lever is at the lock position, the lock valve <NUM> is locked, and the hydraulic fluid is not supplied to the pilot line <NUM>. When the gate lock lever is at the unlock position, the lock valve <NUM> is unlocked, and the hydraulic fluid is'supplied to the pilot line <NUM>.

The hydraulic fluid delivered from hydraulic pump <NUM> is supplied to the travel right hydraulic motor 3a, the travel left hydraulic motor 3b, the swing hydraulic motor <NUM>, the boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM> via the flow control valves <NUM> driven by pilot pressures. The supplied hydraulic fluid causes the boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM> to expand or contract to thereby pivot the boom <NUM>, the arm <NUM>, and the bucket <NUM>, respectively, and change the position and posture of the bucket <NUM>. In addition, the supplied hydraulic fluid rotates the swing hydraulic motor <NUM> to thereby swing the upper swing structure <NUM> relative to the lower travel structure <NUM>. Then, the supplied hydraulic fluid rotates the travel right hydraulic motor 3a and the travel left hydraulic motor 3b to thereby cause the lower travel structure <NUM> to travel. Hereinbelow, the travel hydraulic motors <NUM>, the swing hydraulic motor <NUM>, the boom cylinder <NUM>, the arm cylinder <NUM>, and the bucket cylinder <NUM> are collectively referred to as hydraulic actuators <NUM> to <NUM> in some cases.

<FIG> is a configuration diagram of an MC system included in the hydraulic excavator according to the present embodiment. The MC system in <FIG> includes: the controller <NUM>; a target excavation. surface setting device <NUM> which is an interface on which a target excavation surface <NUM> is set; an operation sensor (operator operation sensor) <NUM> that senses data about operation of the operation levers <NUM> and <NUM> operated by an operator; the posture sensor (excavator posture sensor) <NUM> including the swing angle sensor <NUM> and the angle sensors <NUM> to <NUM>; a work area setting device <NUM> which is an interface for setting a work area <NUM> (work area boundary <NUM>); two GNSS antennas <NUM> for receiving satellite signals used for positioning of the upper swing structure <NUM>; a notification device <NUM> that notifies the operator of various types of data including the states of excavation assistance control and deviation prevention control; and the solenoid proportional valves <NUM> that output pilot pressures for controlling the flow control valves <NUM>.

The controller <NUM> (<NUM>) singly uses the excavation assistance control to control the front work implement 1A in some cases, (<NUM>) singly uses the deviation prevention control to control the front work implement 1A in some cases, and (<NUM>) uses both the excavation assistance control and the deviation prevention control to control the front work implement 1A in some cases. Among them, in the cases (<NUM>) in which the controller <NUM> uses both the excavation assistance control and the deviation prevention control to control the front work implement 1A, the controller <NUM> controls the front work implement 1A such that the operation direction of the bucket <NUM> approximates to the operation direction of the bucket <NUM> when the front work implement 1A is controlled by using only the excavation assistance control (i.e. in the cases (<NUM>)).

For the "excavation assistance control," target velocities related to at least two front implement members in the plurality of front implement members <NUM>, <NUM>, and <NUM> are computed on the basis of postural data obtained by the posture sensor <NUM> and operation data obtained by the operation sensor <NUM> such that the bucket <NUM> positioned at the tip of the work implement 1A moves along a predetermined target excavation surface <NUM> (see <FIG>), and the at least two front implement members, that is, the front work implement 1A, are controlled on the basis of the computed target velocities.

For the "deviation prevention control," a limited velocity related to a front implement member (subject front implement member) which is included in the plurality of front implement members <NUM>, <NUM>, and <NUM>, and is likely to deviate the front work implement 1A from a predetermined work area <NUM> (work area boundary <NUM> (see <FIG>)) is computed on the basis of postural data obtained by the posture sensor <NUM>, and control is performed such that the velocity of the front implement member which is likely to cause the deviation does not exceed the computed limited velocity to thereby prevent the deviation of the front work implement 1A from the work area <NUM>.

Note that a "target velocity related to a front implement member" includes a target velocity of the front implement member itself, and a target velocity of a hydraulic cylinder (actuator) that drives the front implement member. Similarly, a "limited velocity related to a front implement member" includes a limited velocity of the front implement member itself, and a limited velocity of a hydraulic cylinder (actuator) that drives the front implement member.

The controller <NUM>, by programs stored on a storage device (e.g. a hard disk drive or a flash memory) in the controller <NUM> being executed by a processing device (e.g. a CPU), functions as a target excavation surface computing section <NUM>, an operator-operation-velocity estimating section <NUM>, an excavator posture computing section <NUM>, a work area computing section <NUM>, an excavation assistance demanded velocity calculating section <NUM>, a deviation prevention demanded velocity calculating section <NUM>, a notification control section <NUM>, and an actuator control section <NUM>.

The target excavation surface computing section <NUM> measures the position and direction of the upper swing structure (machine body) <NUM> on the basis of satellite signals received at the two GNSS antennas <NUM>, computes the target excavation surface <NUM> on the basis of a result of the measurement and data from the target excavation surface setting device <NUM>, and executes a computation of converting the computed positional data about the target excavation surface <NUM> into positional data in an excavator reference coordinate system depicted in <FIG>. Note that a coordinate system before the conversion is a global coordinate system (geographic coordinate system) or a site reference coordinate system. Note that the direction of the upper swing structure <NUM> may be computed by using the direction of the upper swing structure <NUM> measured at a certain time and a sensing value of the swing angle sensor <NUM>.

The operator-operation-velocity estimating section <NUM> estimates velocities (operator operation velocities) of the hydraulic actuators <NUM>, <NUM>, and <NUM>, according to operator operation, by using a table of a correlation between operation amounts retained in the storage device of the controller <NUM> in advance, and a velocity (actuator velocity) of each of the hydraulic actuators <NUM>, <NUM>, and <NUM>, on the basis of operator operation amounts of the operation levers 22a and 22b sensed by the operation sensor <NUM>. In the present embodiment, furthermore, the computed velocities of the hydraulic actuators <NUM>, <NUM>, and <NUM> are converted into velocities (angular velocities) of the front implement members <NUM>, <NUM>, and <NUM> by using postural data about the excavator <NUM> computed by the excavator posture computing section <NUM> (mentioned below). Note that temporal changes in the angles may be computed from sensing values of the angle sensors <NUM> to <NUM>, and velocities of the front implement members <NUM>, <NUM>, and <NUM> may be calculated on the basis of the computed temporal changes.

The excavator posture computing section <NUM> computes a swing angle of the upper swing structure <NUM> in the excavator reference coordinate system from a sensing value of the swing angle sensor <NUM>. In addition, the excavator posture computing section <NUM> computes the posture of the front work implement 1A (front implement members <NUM>, <NUM>, and <NUM>) in the excavator reference coordinate system from sensing values of the boom angle sensor <NUM>, the arm angle sensor <NUM>, and the bucket angle sensor <NUM>. The posture of the hydraulic excavator <NUM> can be defined on the excavator reference coordinate system (local coordinate system) in <FIG>. The excavator reference coordinate system in <FIG> has its origin at a point which is on the swing center axis, and at which the lower travel structure <NUM> contacts the ground. The X axis of the excavator reference coordinate system is a direction along which the advancing direction of the lower travel structure <NUM> advancing straight and the operation plane of the front work implement 1A become parallel to each other, and along which the operation direction of the extending direction of the front work implement 1A and the operation direction of the lower travel structure <NUM> advancing forward coincide with each other. The Z axis is fixed at the lower surface of the lower travel structure <NUM> (a ground-contacting surface on which the lower travel structure <NUM> touches the ground), and the Y axis is determined to form a right-handed coordinate system with the Z axis at the swing center of the upper swing structure <NUM>. In addition, the swing angle of the upper swing structure <NUM> becomes <NUM> degrees in a state in which the front work implement 1A is parallel to the X axis. The rotation angle of the boom <NUM> relative to the X axis is defined as a boom angle α, the rotation angle of the arm <NUM> relative to the boom <NUM> is defined as an arm angle β, the rotation angle of the claw tip of the bucket <NUM> relative to the arm <NUM> is defined as a bucket angle γ, and the swing angle of the upper swing structure <NUM> relative to the lower travel structure <NUM> is defined as a swing angle δ. The boom angle α is sensed by the boom angle sensor <NUM>, the arm angle β is sensed by the arm angle sensor <NUM>, the bucket angle γ is sensed by the bucket angle sensor <NUM>, and the swing angle δ is sensed by the swing angle sensor <NUM>. By using these types of angle data, and dimensional data Lbm, Lam, and Lbk (see <FIG>) about the front implement members <NUM>, <NUM>, and <NUM>, the posture and position of each section (including the front implement members <NUM>, <NUM>, and <NUM>) of the hydraulic excavator <NUM> in the excavator reference coordinate system can be computed. In addition, the inclination angle θ of the body 1B relative to the horizontal plane (reference plane) orthogonal to the direction of gravity can be sensed by the body inclination angle sensor <NUM>. Note that, in another possible configuration, the controller <NUM> may be connected to the GNSS antennas <NUM>, and the positions and directions of the target excavation surface <NUM>, the work area <NUM>, and the excavator <NUM> in the global coordinate system may be calculated to perform control.

The work area computing section <NUM> executes a computation of converting positional data about the work area boundary <NUM> (work area <NUM>) that an operator can set as desired into positional data in the excavator reference coordinate system, on the basis of data from the work area setting device <NUM>: The work area boundary <NUM> (work area <NUM>) may be defined in the global coordinate system or the site reference coordinate system.

Here, an example of horizontal excavation operation according to the excavation assistance control is depicted in <FIG>. When an operator operates the operation levers <NUM> to perform horizontal excavation by pulling operation of the arm <NUM> in the direction of arrow A, a boom raising command is output as appropriate from the controller <NUM> such that the tip of the bucket <NUM> does not enter the space below the target excavation surface <NUM>, and the solenoid proportional valve 47e is controlled such that raising operation of the boom <NUM> is performed automatically. In addition, the solenoid proportional valve 47c is controlled to perform pulling operation of the arm <NUM> such that an excavation velocity, which is a velocity of the tip of the bucket <NUM> demanded by the operator, or excavation precision, which is positional precision of the tip of the bucket <NUM>, is realized. At this time, for enhancement of the excavation precision, the velocity of the arm <NUM> may be decelerated as necessary. In addition, the solenoid proportional valve <NUM> may be controlled such that the bucket <NUM> is automatically pivoted as appropriate in the direction of arrow C (dumping direction), according to the pulling operation of the arm <NUM>, such that an angle B of the backside of the bucket <NUM> relative to the target excavation surface <NUM> becomes a constant value and levelling work becomes easy. In this manner, the excavation assistance control is control in which the hydraulic cylinders <NUM>, <NUM>, and <NUM> are controlled automatically or semi-automatically in response to operation of the front work implement 1A operated by the operator, and front implement members like the boom <NUM>, the arm <NUM>, and the bucket <NUM> are operated to attain the desired excavation profile (target excavation surface <NUM>).

In the deviation prevention control, when operation of the front work implement 1A and the upper swing structure <NUM> are instructed by using the operation devices <NUM>, the operation of the hydraulic cylinders <NUM>, <NUM>, and <NUM> is decelerated or stopped to prevent deviation from the work area <NUM> on the basis of the predetermined work area boundary <NUM>, the position of each section of the excavator, and operation data about the operation devices <NUM>.

Here, an example of limitation of actuator operation according to the deviation prevention control is depicted in <FIG> depicts state S1 and state S2 in one cycle of repeatedly-performed excavation work. In state S1, excavation work has ended, and the front work implement 1A is folded. In state S2, reaching work is being performed for next excavation work. When the state transitions from state S1 to state S2, an operator implements raising operation of the boom <NUM> in order to prevent a contact between the bucket <NUM> and the target excavation surface <NUM>, but when the raising operation of the boom <NUM> is excessive, there is a possibility that, for example, a rear end section <NUM> of the arm <NUM> goesbeyond the work area boundary <NUM>, and deviates from the work area <NUM>. In view of this, by the deviation prevention control, a command for decelerating the raising operation of the boom <NUM> (i.e. extending operation of the boom cylinder <NUM>) is computed in order to prevent deviation of the rear end section <NUM> of the arm <NUM> from the work area <NUM> when the raising operation of the boom <NUM> is excessive in a situation like the one depicted in <FIG> where the state transitions from state S1 to state S2. In this manner, the deviation prevention control is control in which an actuator is decelerated or stopped in response to operation performed by the operator, and deviation from the work area <NUM> is prevented.

Returning to <FIG>, the excavation assistance demanded velocity calculating section (target velocity calculating section) <NUM> computes excavation assistance demanded velocities, which are target velocities related to at least two front implement members (e.g. the arm <NUM> and the boom <NUM>) in the three front implement members <NUM>, <NUM>, and <NUM>, such that the bucket <NUM> operates along the predetermined target excavation surface <NUM> when there is operation of an operation lever by the operator (e.g. operation of the arm <NUM>). For example, the excavation assistance demanded velocity calculating section <NUM> computes the excavation assistance demanded velocities (target velocities) on the basis of postural data about the front work implement 1A computed from a sensing value of the posture sensor <NUM>, operation data (operation amounts) about the operation levers <NUM> computed from a sensing value of the operation sensor <NUM>, positional data about the target excavation surface <NUM> computed at the target excavation surface computing section <NUM>, and positional data about the upper swing structure <NUM> computed from satellite signals received by the GNSS antennas <NUM>.

The deviation prevention demanded velocity calculating section (limited velocity calculating section) <NUM> computes a deviation prevention demanded velocity, which is a limited velocity related to a front implement member that is included in the plurality of three front implement members <NUM>, <NUM>, and <NUM> and that islikely to deviate from the work area. <NUM>, such that the front work implement 1A does not go beyond the work area boundary <NUM> and does not deviate from the predetermined work area <NUM> (i.e. such that entry into an entry prohibited area is prevented). For example, the deviation prevention demanded velocity calculating section <NUM> computes the deviation prevention demanded velocity (limited velocity) on the basis of positional data about the work area boundary <NUM> computed at the work area computing section <NUM>, postural data about the front work implement 1A computed from a sensing value of the posture sensor <NUM>, an operator operation velocity computed at the operator-operation-velocity estimating section <NUM>, and excavation assistance demanded velocities computed at the excavation assistance demanded velocity calculating section <NUM>. The deviation prevention demanded velocity becomes closer to zero as the distance between the front work implement 1A and the work area boundary <NUM> becomes closer to, zero. The deviation prevention demanded velocity can be a limited velocity of an excavation assistance demanded velocity (target velocity) computed at the excavation assistance demanded velocity calculating section <NUM> during execution of the excavation assistance control. On the other hand, when there is not intervention by the excavation assistance control or when the excavation assistance control is disabled, the deviation prevention demanded velocity can be a limited velocity of the operator operation velocity computed at the operator-operation-velocity estimating section <NUM>. When an excavation assistance demanded velocity or an operator operation velocity of a front implement member exceeds the deviation prevention demanded velocity, the velocity related to the front implement member is limited to the deviation prevention demanded velocity, and the front implement member is forcibly decelerated or stopped. On the contrary, when an excavation assistance demanded velocity or an operator operation velocity of a front implement member is equal to or lower than the deviation prevention demanded velocity, the velocity related to the front implement member is not limited, and the front member is controlled according to the excavation assistance demanded velocity or the operator operation velocity.

Furthermore, the deviation prevention demanded velocity calculating section <NUM> according to the present embodiment decides whether there is a front implement member (referred to as a "subject front implement member" in some cases) that is included in at least two front implement members for which excavation assistance demanded velocities (target velocities) have been computed at the excavation assistance demanded velocity calculating section <NUM>, and for which a deviation prevention demanded velocity (limited velocity) has been computed at the deviation prevention demanded velocity calculating section <NUM>, and whether or not an excavation assistance demanded velocity (target velocity) related to the subject front. implement member exceeds the deviation prevention demanded velocity (limited velocity) related to the subject front implement member. Then, when the excavation assistance demanded velocity (target velocity) related to the subject front implement member exceeds the deviation prevention demanded velocity (limited velocity), a deviation prevention demanded velocity related to the remaining front implement member which is included in the at least two front implement members for which the excavation assistance demanded velocities (target velocities) have been computed at the excavation assistance demanded velocity calculating section <NUM>, and is not the subject front implement member is computed on the basis of the deviation prevention demanded velocity related to the subject front implement member. It should be noted however that in the computation of the deviation prevention demanded velocity of the remaining front implement member, the deviation prevention demanded velocity of the remaining front implement member is calculated such that the operation direction of the bucket <NUM> (the direction of a velocity vector of the bucket tip) defined by the deviation prevention demanded velocity of the subject front implement member and the deviation prevention demanded velocity of the remaining front implement member approximates to or matches the operation direction of the bucket defined by the excavation assistance demanded velocities (target velocities) of the at least two front implement members (a specific example of the computation is mentioned below by using <FIG> and <FIG>). Then, the deviation prevention demanded velocities of the subject front implement member and the remaining front implement member are output to the actuator control section <NUM>. Thereby, even if the front work implement 1A approaches the work area boundary <NUM>, and the deviation prevention control intervenes, significant changes in the operation direction of the bucket <NUM> defined by the excavation assistance control are suppressed.

The notification control section <NUM> outputs a command signal to the notification device <NUM> such that the notification device <NUM> outputs work assistance information. For example, the work assistance information output by the notification device <NUM> includes: information about presence or absence of deceleration of the front implement members <NUM>, <NUM>, and <NUM> according to the deviation prevention control; identification data (e.g. a name or an image) about a front implement member decelerated by the control; the activation status of the deviation prevention control and the excavation assistance control; a positional relation between the bucket <NUM> and the target excavation surface <NUM>; and a positional relation between the work implement 1A and the work area <NUM> (work area boundary <NUM>). For example, examples of the notification device <NUM> include a monitor, a speaker, and a warning light, and the notification device <NUM> can be configured with any one of these or with a combination of a plurality of these.

The actuator control section <NUM> outputs, to the solenoid proportional valves, command signals necessary for controlling operation of the front implement members <NUM>, <NUM>, and <NUM> according to velocities (referred to as "control demanded velocities" in some cases) output from the deviation prevention demanded velocity calculating section <NUM>. Examples of the control demanded velocity include operator operation velocities, excavation assistance demanded velocities before correction, deviation prevention demanded velocities, and excavation assistance demanded velocities after correction.

Here, an example in which the front work implement 1A is controlled such that the tip (control point) of the bucket <NUM> is positioned on or above the target excavation surface <NUM> by automatically adding operation of raising the boom <NUM> to operation of the arm <NUM> operated by an operator is explained as an example of the excavation assistance control by using <FIG> and <FIG>.

<FIG> is a flowchart of a process executed by the excavation assistance demanded velocity calculating section <NUM> in the controller <NUM>. In the case considered here, as depicted in an upper right legend in <FIG>, it is supposed that a velocity vector B is generated at the tip of the bucket <NUM> due to arm operation by the operator, and boom raising operation that generates a velocity vector C is automatically added to the arm operation that generates the velocity vector B, such that a component (vertical component) of a velocity vector actually generated at the tip of the bucket <NUM>, the component being perpendicular to the target excavation surface <NUM>, is limited to a limited value az defined in <FIG>.

At Step S200, the excavation assistance demanded velocity calculating section <NUM> computes the velocity vector B of the tip of the bucket <NUM> generated by the operator operation on the basis of operation velocity data (velocity data (angular velocity data) about the front implement members <NUM>, <NUM>, and <NUM> estimated from the operator operation) about the front work implement 1A from the operator-operation-velocity estimating section <NUM>, and postural data about the front work implement 1A from the excavator posture computing section <NUM>.

At Step S201, the excavation assistance demanded velocity calculating section <NUM> calculates a distance D from the tip of the bucket <NUM> to the target excavation surface <NUM> from the position (coordinates) of the tip of the bucket <NUM> computed at the excavator posture computing section <NUM> and a distance of a straight line including the target excavation surface <NUM> from the target excavation surface computing section <NUM>. Then, on the basis of the distance D and the graph in <FIG>, the limited value az of the component of the velocity vector of the tip of the bucket <NUM>, the component being perpendicular to the target excavation surface <NUM>, is calculated.

At Step S202, the excavation assistance demanded velocity calculating section <NUM> acquires a component bz of the velocity vector B of the tip of the bucket <NUM> according to the operator operation calculated at Step S200, the component bz being perpendicular to the target excavation surface <NUM>.

At S203, the excavation assistance demanded velocity calculating section <NUM> decides whether or not the limited value az calculated at S201 is equal to or larger than <NUM>. Note that xz coordinates are set as depicted in the upper right portion in <FIG>. In the xz coordinates, the rightward direction in the figure, which is parallel to the target excavation surface <NUM>, is defined as the positive direction of the x axis, and the upward direction, in the figure, perpendicular to the target excavation surface <NUM> is defined as the positive direction of the z axis. In the legend in <FIG>, the vertical component bz and the limited value az point to the negative direction, and a horizontal component bx, a horizontal component cx, and a vertical component cz point to the positive directions. In addition, the legend in <FIG> depicts a situation where the target excavation surface is located below the tip of the bucket <NUM>. Then, on the basis of <FIG>, a case where the limited value az is <NUM> is a case where the distance D is <NUM>, that is, the tip of the bucket <NUM> is positioned on the target excavation surface <NUM>, a case where the limited value az is a positive value is a case where the distance D is a negative distance, that is, the tip of the bucket <NUM> is positioned below the target excavation surface <NUM>, and a case where the limited value az is a negative value is a case where the distance D is a positive value, that is, the tip of the bucket <NUM> is positioned above the target excavation surface <NUM>. When it is decided at S203 that the limited value az is equal to or larger than <NUM> (i.e. a case where the tip of the bucket <NUM> is positioned on or below the target excavation surface <NUM>), the process proceeds to S204, and when the limited value az is smaller than <NUM>, the process proceeds to S206.

At S204, the excavation assistance demanded velocity calculating section <NUM> decides whether or not the vertical component bz of the velocity vector B of the tip of the bucket <NUM> according to the operator operation is equal to or larger than <NUM>. When bz is a positive value, this represents that the vertical component bz of the velocity vector B points to the upward direction, and when bz is a negative value, this represent that the vertical component bz of the velocity vector B points to the downward direction. When it is decided at S204 that the vertical component bz is equal to or larger than <NUM> (i.e. a case where the vertical component bz points to the upward direction), the process proceeds to S205, and when the vertical component bz is smaller than <NUM>, the process proceeds to S208.

At S205, the excavation assistance demanded velocity calculating section <NUM> compares the absolute values of the limited value az and the vertical component bz with each other, and when the absolute value of the limited value az isequal to or larger than the absolute value of the vertical component bz, the process proceeds to S208. On the other hand, when the absolute value of the limited value az is smaller than the absolute value of the vertical component by, the process proceeds to S211.

At S208, the excavation assistance demanded velocity calculating section <NUM> selects "cz = az - bz" as a formula for calculating the component cz of the velocity vector C of the tip of the bucket <NUM> that should be generated by operation of the boom <NUM> according to the excavation assistance control, the component cz being perpendicular to the target excavation surface <NUM>, and calculates the vertical component cz on the basis of the formula, the limited value az calculated at S201, and the vertical component bz acquired at S202. Then, at Step S209, the velocity vector C that can output the calculated vertical component cz is calculated, and the horizontal component is set as cx.

At S210, the excavation assistance demanded velocity calculating section <NUM> calculates a target velocity vector T. If a component of the target velocity vector T, the component being perpendicular to the target excavation surface <NUM>, is defined as tz, and a horizontal component of the target velocity vector T is tx, they can be represented by "tz = bz + cz, tx = bx + cx," respectively. Assigning these to the formula (cz = az - bz) in S208 gives "tz = az, tx = bx + cx" about the target velocity vector T after all. That is, the vertical component tz of the target velocity vector when the process has reached S210 is limited to the limited value az, and automatic boom raising according to the excavation assistance control is activated.

At S206, the excavation assistance demanded velocity calculating section <NUM> decides whether or not the vertical component bz of the velocity vector B of the claw tip according to the operator operation is equal to or larger than <NUM>. When it is decided at S206 that the vertical component bz is equal to or larger than <NUM> (i.e. a case, where the vertical component bz points to the upward direction), the process proceeds to S211, and when the vertical component bz is smaller than <NUM>, the process proceeds to S207.

At S207, the excavation assistance demanded velocity calculating section <NUM> compares the absolute values of the limited value az and the vertical component bz with each other, and when the absolute value of the limited value az is equal to or larger than the absolute value of the vertical component bz, the process proceeds to S211. On the other hand, when the absolute value of the limited value az is smaller than the absolute value of the vertical component bz, the process proceeds to S208.

When the process has reached S211, the velocity vector C is set to zero because it is not necessary to operate the boom <NUM> by the excavation assistance control. In this case, the target velocity vector T calculated at Step S212 is "tz = bz, tx = bx" on the basis of the formula (tz = bz + cz, tx = bx + cx) used at S210, and matches the velocity vector B according to the operator operation.

At S213, the excavation assistance demanded velocity calculating section <NUM> computes excavation assistance demanded velocities of the front implement members <NUM>, <NUM>, and <NUM> on the basis of the target velocity vector T (tz, tx) determined at S210 or S212, and outputs them to the deviation prevention demanded velocity calculating section <NUM>. In the present embodiment, it is supposed that the excavation assistance demanded velocities are computed for the boom <NUM> and the arm <NUM>.

As a result of the processing above, when the vertical component of the velocity vector B exceeds the limited value az, boom operation to generate the velocity vector C is added automatically, and thereby the vertical component of the velocity vector of the tip of the bucket <NUM> is maintained at the limited value az. The limited value az is set such that it approaches zero as the tip of the bucket <NUM> approaches the target excavation surface <NUM>, but because the horizontal component of the velocity vector of the tip of the bucket <NUM> is the sum of the horizontal components of the velocity vectors B and C and is not limited, the tip of the bucket <NUM> can be moved along the target excavation surface <NUM> on the target excavation surface <NUM>.

<FIG> is a flowchart of a process executed by the deviation prevention demanded velocity calculating section <NUM> in the controller <NUM>. Note that Steps S105, S106, and S107, in processes at Steps S100 to S108 that are depicted are processes that are to be performed when the excavation assistance control and the deviation prevention control are executed simultaneously.

At Step S100, the deviation prevention demanded velocity calculating section <NUM> acquires data from the work area computing section <NUM>, and determines whether or not the work area <NUM> (or the work area boundary <NUM>) has been set. When it is determined that the work area <NUM> has been set, the process proceeds to Step S101, and when it is determined that the work area <NUM> has not been set, the process proceeds to Step S108.

At Step S101, the deviation prevention demanded velocity calculating section <NUM> determines whether or not there is a front implement member that is likely to deviate the front work implement 1A from the work area <NUM> when the front implement members <NUM>, <NUM>, and <NUM> are operated from the current posture. In the present embodiment, the aforementioned determination is made on the basis of whether or not the front work implement 1A reaches the work area boundary <NUM> when each of the boom <NUM>, the arm <NUM>, and the bucket <NUM> is operated singly to the limit of its movable range from the current posture. When it is determined that at least one front implement member in the three front implement members <NUM>, <NUM>, and <NUM> can deviate the front work implement 1A from the work area <NUM>, the process proceeds to Step S102, and when it is determined that none of the front implement members <NUM>, <NUM>, and <NUM> deviates the front work implement 1A from the work area <NUM>, the process proceeds to Step S108.

At Step S102, the deviation prevention demanded velocity calculating section <NUM>, on the basis of the posture of the front work implement 1A and positional data about the work area boundary <NUM>, calculates a target stop angle θt which is an angle to be formed when the front work implement 1A reaches the work area boundary <NUM> when each of the boom <NUM>, the arm <NUM>, and the bucket <NUM> is singly operated to the limit of its movable range from the current posture. The target stop angle θt is defined similarly to the pivot angles α, β, and γ of the front implement members <NUM>, <NUM>, and <NUM>. A calculation of the target stop angle θt is mentioned in detail by using <FIG>.

First, in <FIG>, a position (height) Zamr of an arm rear end section 9b can be calculated according to the following Formula (<NUM>). It should be noted however that, as depicted in <FIG>, Lbm is the distance between the boom pin 8a and the arm pin 9a, Lbs is the distance from the arm pin 9a to the arm rear end section 9b, and τ is geometric data (angle) related to the arm <NUM>. [Equation <NUM>] <MAT>.

By using the geometric data about the hydraulic excavator <NUM> including the front work implement 1A in this manner, it is possible to similarly calculate the positions of other portions of the front work implement 1A also. The calculation of a target stop angle θt is implemented for each of front implement members for which a result of the decision at Step S101 has been Yes, and the calculation of a target stop angle θt is not implemented for a front implement member for which a result of the decision is No..

Here, if the distance from the origin of the coordinate system of the excavator <NUM> to the upper work area boundary <NUM> is Dist, and the distance in the Z-axis direction from the origin of the coordinate system of the excavator <NUM> to the boom pin 8a is Loz, a target stop angle θtbm of the boom <NUM> when only the boom <NUM> operates from the current posture is represented by the following Formula (<NUM>). Note that A and B are values related to the R-alpha method of trigonometric functions. [Equation <NUM>]
<MAT>.

At Step S103, the deviation prevention demanded velocity calculating section <NUM> calculates a deviation prevention demanded velocity ωa of a subject front implement member from the current posture of the front work implement 1A and the target stop angle θt computed at Step S102. The calculation of the deviation prevention demanded velocity ωa can be implemented as in the following Formula (<NUM>), for example. It should be noted however that ωa is the deviation prevention demanded velocity of the subject front implement member, da is a degree of deceleration of the subject front implement member, θt is the target stop angle of the subject front implement member, and θc is the current angle of the subject front implement member. [Equation <NUM>] <MAT>.

The calculation of a deviation prevention demanded velocity ωa at Step S103 is implemented for each of the front implement members for which a result of the decision at Step S101 is Yes, and a deviation prevention demanded velocity ωa of the front implement member for which a result of the decision is No is set to an excavation assistance demanded velocity.

At Step S104, the deviation prevention demanded velocity calculating section <NUM> determines whether or not the excavation assistance demanded velocity of the front implement member (subject front implement member) for which the deviation prevention demanded velocity ωa has been calculated at Step S103 exceeds the deviation prevention demanded velocity ωa of the subject front implement member. When the excavation assistance demanded velocity exceeds the deviation prevention demanded velocity ωa, the excavation assistance demanded velocity is reduced to the deviation prevention demanded velocity, and when the excavation assistance demanded velocity does not exceed the deviation prevention demanded velocity ωa, velocity limitation of the excavation assistance demanded velocity is not performed. Here, when it is determined that the excavation assistance demanded velocity of at least one front implement member which is included in the at least two front implement members (here, the arm <NUM>, and the boom <NUM>) for which the excavation assistance demanded velocities have been computed exceeds its deviation prevention demanded velocity ωa, the process proceeds to Step S105. On the other hand, when it is determined that none of the excavation assistance demanded velocities exceed their deviation prevention demanded velocities ωa, the process proceeds to Step S108.

At Step S105, the deviation prevention demanded velocity calculating section <NUM>, regarding the front - implement member whose excavation assistance demanded velocity has been decided as exceeding the deviation prevention demanded velocity wa at Step S104, calculates a deceleration ratio Dr of an actuator (hydraulic cylinder) to be decelerated from the excavation assistance demanded velocity. Here, if the excavation assistance demanded velocity is defined as wmc, and the deviation prevention demanded velocity is defined as ωa, the deceleration ratio Dr can be calculated in the following manner. Note that the ratio (ωa/ωmc) of the deviation prevention demanded velocity ωa to the excavation assistance demanded velocity ωmc is referred to as a velocity ratio in some cases. [Equation <NUM>] <MAT>.

According to Formula (<NUM>) described above, the velocity ratio (ωa/ωmc) becomes zero (smallest value), and the deceleration ratio Dr becomes <NUM> (largest value) when the deviation prevention demanded velocity ωa is zero at which the subject front implement member is decelerated most. Regarding the front implement member for which a deviation prevention demanded velocity ωa has not been computed, the deviation prevention demanded velocity ωa is set to the excavation assistance demanded velocity ωmc, and the velocity ratio (ωa/ωmc) becomes <NUM> (largest value), and the deceleration ratio Dr becomes zero (smallest value) in this case.

The calculation of a velocity ratio (ωa/ωmc) and a deceleration ratio Dr at Step S105 is implemented for all of the at least two front implement members (here, the boom <NUM>, and the arm <NUM>) for which the excavation assistance demanded velocities have been computed.

At Step S106, the deviation prevention demanded velocity calculating section <NUM> calculates again the deviation prevention demanded velocity ωa of a remaining front implement member, which is included in all of the front implement members for which the deceleration ratios Dr have been calculated at Step S105 and which is not the one having the largest deceleration ratio Dr, such that the deceleration ratio of the remaining front implement member matches the deceleration ratio (reference deceleration ratio) of the front implement member having the largest deceleration ratio Dr. Thereby, the operation direction of the bucket <NUM> defined by the deviation prevention demanded velocity ωa related to the subject front implement member and the deviation prevention demanded velocity ωa related to the remaining front implement member matches the operation direction of the bucket <NUM> defined by the excavation assistance demanded velocities ωmc related to the at least two front implement members for which the excavation assistance demanded velocities ωmc have been computed. For example, when a deviation prevention demanded velocity wabm of the boom <NUM> becomes zero, that is, when the velocity ratio becomes zero and the deceleration ratio becomes <NUM>, deviation prevention demanded velocities ωaam and coabk of the arm <NUM> and the bucket <NUM> are corrected to zero as a result of the process at Step S106 even if the deceleration ratios Dr of the arm <NUM> and the bucket <NUM> computed at Step S105 are smaller than <NUM>.

At Step S107, the deviation prevention demanded velocity calculating section <NUM> outputs, as the control demanded velocity of each front implement member, the deviation prevention demanded velocity wa of each front implement member calculated at Step S106.

When the process has reached Step S108, the deviation prevention demanded velocity calculating section <NUM> outputs the excavation assistance demanded velocities as the control demanded velocities.

The control demanded velocities output by the deviation prevention demanded velocity calculating section <NUM> at Step S107 or S108 are input to the actuator control section <NUM> depicted in <FIG>. The actuator control section <NUM> converts the control demanded velocities which are angular velocities of the front implement members into control demanded actuator velocities which are velocities of actuators corresponding to the front implement members. Then, the actuator control section <NUM> outputs command values to realize the control demanded actuator velocities to corresponding solenoid proportional valves <NUM>. Thereby, the solenoid proportional valves <NUM> operate to apply pilot pressures to flow control valves <NUM>, applicable hydraulic cylinders operate according to the control demanded actuator velocities, and the excavation assistance control and the deviation prevention control are realized.

Note that when MC (the excavation assistance control and the deviation prevention control) is not enabled in each step depicted in <FIG>, each step may be executed by reading excavation assistance demanded velocities as meaning operator operation velocities.

In addition, whereas the deceleration ratio Dr is used to compute the deviation prevention demanded velocity of the remaining front implement member at Steps S105 and S106 in the example in <FIG>, the velocity ratio (ωa/ωmc) may be used. In this case, the velocity ratio (ωa/ωmc) of the subject front implement member is used as the reference velocity ratio, and the deviation prevention velocity related to the remaining front implement member, which is included in the at least two front implement members for which the excavation assistance demanded velocities have been computed and which is not the subject front implement member, is computed such that the velocity ratio (ωa/ωmc) of the remaining front implement member matches the reference velocity ratio. Note that when there are two or more subject front implement members, a velocity ratio (coa/comc) of each of the two or more subject front implement members may be calculated, and the smallest velocity ratio of the plurality of calculated velocity ratios (ωa/ωmc) may be used as the reference velocity ratio to compute the deviation prevention demanded velocity of the remaining front implement member.

Next, a situation where the controller <NUM> controls the front work implement 1A by using both the excavation assistance control and the deviation prevention control is explained.

First, in the example in <FIG>, the work area boundary <NUM> is set below the target excavation surface <NUM>. If an operator inputs arm crowding operation to the operation levers <NUM> in the situation in <FIG>, by the excavation assistance control of the controller <NUM>, an excavation assistance demanded velocity of boom raising (an excavation assistance demanded velocity of the boom <NUM>) for moving the bucket tip along the target excavation surface <NUM> is calculated for an operator operation velocity of the arm <NUM> (an excavation assistance demanded velocity of the arm <NUM>) computed from the arm crowding operation performed by the operator (i.e. excavation assistance demanded velocities of the arm <NUM> and the boom <NUM> are computed). On the other hand, it is supposed that because the front work implement 1A has approached the work area boundary <NUM> due to the arm crowding operation by the operator, by the deviation prevention control of the controller <NUM>, a deviation prevention demanded velocity lower than the operator operation velocity of the arm <NUM> (the excavation assistance demanded velocity of the arm <NUM>) has been computed (i.e. a deviation prevention demanded velocity of the arm <NUM> in the arm <NUM> and the boom <NUM> for which the excavation assistance demanded velocities have been computed has been computed).

In the situation described above, in conventional technologies, whereas arm crowding is reduced in velocity from the excavation assistance demanded velocity (operator operation velocity) to the deviation prevention demanded velocity, boom raising is not reduced, but is kept at the excavation assistance demanded velocity. Accordingly, the boom raising becomes excessive relative to the arm crowding, and there is a fear that the bucket tip floats above from the target excavation surface <NUM>, and excavation along the target excavation surface <NUM> becomes impossible.

However, the controller <NUM> (deviation prevention demanded velocity calculating section <NUM>) according to the present embodiment computes also a deviation prevention demanded velocity of the boom raising according to the calculated deviation prevention demanded velocity of the arm crowding such that the direction of the velocity vector of the bucket tip does not change even if the magnitude of the velocity vector is reduced by execution of the deviation prevention control. Because of this, even if the excavation assistance control and the deviation prevention control function simultaneously, the bucket tip moves along the target excavation surface <NUM>, and thus excavation along the target excavation surface <NUM> becomes possible.

Next, in the example in <FIG>, the target excavation surface <NUM> is set below the excavator <NUM>, and the work area boundary <NUM> is set in front of the excavator <NUM>. If an operator inputs arm dumping operation (pressing operation) to the operation levers <NUM> in the situation in <FIG>, by the excavation assistance control of the controller <NUM>, an excavation assistance demanded velocity of boom lowering (an excavation assistance demanded velocity of the boom <NUM>) for moving the bucket tip along the target excavation surface <NUM> is calculated for an operator operation velocity of the arm <NUM> (an excavation assistance demanded velocity of the arm <NUM>) computed from the arm dumping operation performed by the operator (i.e. excavation assistance demanded velocities of the arm <NUM> and the boom <NUM> are computed). On the other hand, it is supposed that because the front work implement 1A has approached the work area boundary <NUM> due to the arm dumping operation by the operator, by the deviation prevention control of the controller <NUM>, a deviation prevention demanded velocity lower than the operator operation velocity of the arm <NUM> (the excavation assistance demanded velocity of the arm <NUM>) has been computed (i.e. a deviation prevention demanded velocity of the arm <NUM> in the arm <NUM> and the boom <NUM> for which the excavation assistance demanded velocities have been computed has been computed).

In this situation also, in conventional technologies, whereas arm dumping is reduced in velocity from the excavation assistance demanded velocity (operator operation velocity) to the deviation prevention demanded velocity, boom lowering is not reduced, but is kept at the excavation assistance demanded velocity. Accordingly, the boom lowering becomes excessive relative to the arm dumping, and there is a fear that the bucket tip goes down below the target excavation surface <NUM>, and excavation along the target excavation surface <NUM> becomes impossible.

However, the controller <NUM> (deviation prevention demanded velocity calculating section <NUM>) according to the present embodiment computes also a deviation prevention demanded velocity of the boom lowering according to the calculated deviation prevention demanded velocity of the arm dumping such that the direction of the velocity vector of the bucket tip does not change even if the magnitude of the velocity vector is reduced by execution of the deviation prevention control. Because of this, even if the excavation assistance control and the deviation prevention control operate simultaneously, the bucket tip moves along the target excavation surface <NUM>, and thus excavation along the target excavation surface <NUM> becomes possible.

The hydraulic excavator <NUM> configured in the manner described above can realize the deviation prevention control by which when there is a possibility that the front work implement 1A deviates from the work area <NUM>, the velocity of a front implement member is decelerated or stopped at a predetermined degree of deceleration while the direction of a velocity vector of the tip of the bucket <NUM> computed by the excavation assistance demanded velocity calculating section <NUM> is maintained. That is, when there is not a possibility that the front work implement 1A reaches the work area boundary <NUM> from the current posture, the deviation prevention control does not function, but the front work implement 1A operates according to an excavation assistance demanded velocity or an operator operation velocity. In addition, when an excavation assistance demanded velocity of at least one front implement member exceeds a deviation prevention demanded velocity, another front implement member for which an excavation assistance demanded velocity has been computed also is decelerated at the same deceleration ratio. with the configuration in this manner, even if at least one front implement member in a plurality of front implement members (e.g. the arm <NUM> and the boom <NUM>) is decelerated or stopped by the deviation prevention control in a situation where the plurality of front implement members are operating according to the excavation assistance control, the remaining front implement member is similarly decelerated or stopped according to it, and thus variations of a velocity vector of the bucket tip before and after the activation of a deviation prevention demanded velocity can be prevented.

In addition, in the calculation of the deviation prevention demanded velocity at Step S103, it may be made possible for an operator to change the value of the degree of deceleration da of the subject front implement member, and values of individual front implement members (i.e. individual hydraulic cylinders) may be made changeable. Thereby, for example, by setting the absolute value of a degree of deceleration to a relatively small value for an operator who is inexperienced with operation of the excavator <NUM>, the deviation prevention control intervenes earlier than in a case where the absolute value is relatively large, and the front work implement 1A is decelerated and stopped moderately.

The hydraulic excavator <NUM> according to the present embodiment includes the controller <NUM> having the deviation prevention demanded velocity calculating section <NUM> that performs computation processes that are different from the first embodiment. In other respects, the present embodiment is the same as the first embodiment, and the following explains the processes performed by the deviation prevention demanded velocity calculating section <NUM> by using <FIG>. Note that processes (Steps S100, S101, S102, and S108) which are processes in <FIG>, but are the same as those in <FIG> of the first embodiment are given the same reference characters, and explanations thereof are omitted.

At Step S303, for each front implement member decided as being likely to deviate the front work implement 1A from the work area <NUM> at Step S101, the deviation prevention demanded velocity calculating section <NUM> calculates a deceleration coefficient on the basis of the current posture (the pivot angle α, β, or γ of each front implement member), and a target stop angle θt. The deceleration coefficient is defined within the range of <NUM> to <NUM> as depicted in <FIG>. The smaller the difference between the target stop angle θt and the current pivot angle is, the smaller the value of the deceleration coefficient is. It is assumed that when the deceleration coefficient is <NUM>, the velocity of the front implement member becomes <NUM>, and when the deceleration coefficient is <NUM>, the front implement member is not decelerated. The relation between the deceleration coefficient, the target stop angle, and the current posture (pivot angle) may be defined linearly from the point where the difference becomes equal to or smaller than dth1 as represented by a solid line, or may be defined by a curve expressed by a polynomial from the point where the difference becomes equal to or smaller than dth2 as represented by a broken line.

At Step S304, it is determined whether a deceleration coefficient of at least one front implement member in the front implement members for which deceleration coefficients have been computed at Step S303 is different from <NUM>, in other words, whether it is necessary to decelerate at least one front implement member from its excavation assistance demanded velocity. Here, when it is determined that a deceleration coefficient of at least one front implement member is different from <NUM>, the process proceeds to Step S305, and when it is not determined so, the process proceeds to Step S108.

At Step S305, the excavation assistance demanded velocities of all the actuators (hydraulic cylinders) for which excavation assistance demanded velocities have been computed are decelerated at the smallest deceleration coefficient in the deceleration coefficients computed at Step S303. For example, when regarding the deceleration coefficients calculated at Step S303, the deceleration coefficient of the boom is <NUM>, and the deceleration coefficients. of the arm and the bucket are <NUM>, the arm and the bucket are also decelerated at the deceleration coefficient <NUM> at Step S305.

At Step S306, excavation assistance demanded velocities decelerated at Step S305 (deviation prevention demanded velocities) are output as control demanded velocities.

According to the hydraulic excavator including the controller <NUM> (deviation prevention demanded velocity calculating section <NUM>) that functions in the manner mentioned above, according to a deceleration coefficient of a front implement member whose excavation assistance demanded velocity is decelerated most significantly, excavation assistance demanded velocities of other front implement members are also decelerated. Thereby, similarly to the first embodiment, the operation direction of the bucket <NUM> defined by the excavation assistance demanded velocity of each front implement member reduced according to the deceleration coefficient matches the operation direction of the bucket <NUM> defined by the excavation assistance demanded velocity of each front implement member. Because of this, even if the excavation assistance control and the deviation prevention control function simultaneously, the bucket tip moves along the target excavation surface <NUM>, and thus excavation along the target excavation surface <NUM> becomes possible.

Note that whereas, in the cases explained in the embodiments described above, when the controller controls the front work implement 1A by using both the excavation assistance control and the deviation prevention control, the front work implement 1A is controlled such that the operation direction of the bucket <NUM> matches the operation direction of the bucket <NUM> that is to be generated when the front work implement 1A is controlled by using only the excavation assistance control, the front work implement 1A may be controlled such that the operation direction of the bucket <NUM> approximates to the operation direction of the bucket <NUM> that is to be generated when the front work implement 1A is controlled by using only the excavation assistance control. That is, the operation directions of the bucket <NUM> that are seen in both the cases need not to match completely, and they may be different only to such an extent that demanded construction precision of the target excavation surface <NUM> is satisfied.

In addition, whereas the configuration is explained by mentioning as an example the work machine including electric levers as the operation levers <NUM> and <NUM> in the embodiments described above, the present invention can also be applied to a work machine including hydraulic levers.

In addition, in another possible configuration, that both the excavation assistance control and the deviation prevention control are being executed is notified to an operator by using the notification device <NUM>. Examples of the configuration include, for example, a configuration in which that excavation assistance demanded velocities related to at least two front implement members (i.e. a subject front implement member and a remaining front implement member) that are computed by the excavation assistance demanded velocity calculating section <NUM> of the controller <NUM> are corrected (decelerated) on the basis of deviation prevention demanded velocities computed by the deviation prevention demanded velocity calculating section <NUM> is notified by the notification device <NUM>. Furthermore, data (identification data (e.g. names or images of front implement members)) that can identify the at least two front implement members whose excavation assistance demanded velocities are corrected (decelerated) may be notified by the notification device <NUM>. Then, when the at least two front implement members for which computations are performed by the excavation assistance demanded velocity calculating section <NUM> are stopped by the deviation prevention control, data to that effect or the identification data of the at least two front implement members may be notified by the notification device <NUM>. In addition, when the subject front implement member is decelerated by the deviation prevention control, data to that effect or the identification data of the subject front implement member may be notified by the notification device <NUM>, or when the subject front implement member is stopped, data to that effect or the identification data of the subject front implement member may be notified by the notification device <NUM>. A decision as to whether there is deceleration or a stop may be made by using a deceleration ratio Dr calculated at Step S105 in <FIG>. In addition, when a notification is made, data (identification data) that can identify a front implement member stopped by the deviation prevention control or data that can specify a front implement member (hydraulic cylinder) whose deceleration ratio Dr is the largest may be provided to an operator. By notifying an operator of a reason why the behavior of the front work implement 1A is changed by the deviation prevention control in the manner mentioned above, a sense of discomfort felt by the operator can be reduced. Note that the form of a notification is not limited to display on a monitor display, but, for example, a warning sound including consecutive buzzer sounds may be output from a speaker, or a warning light may be turned on.

In addition, in another possible configuration that may be adopted as the configuration of the controller <NUM>, excavation assistance demanded velocities are calculated by the excavation assistance demanded velocity calculating section <NUM>, deviation prevention demanded velocities are calculated by the deviation prevention demanded velocity calculating section <NUM>, an arbitrating section that executes ` a process of arbitrating the demanded velocities (specifically, the processes at Steps S104 to S107 in <FIG>, and the processes at Steps S304, <NUM>, and <NUM> in <FIG>) is installed additionally, and the demanded velocities after being arbitrated are output to the actuator control section <NUM>.

Note that, in the case explained in the description above, as velocities (excavation assistance demanded velocities and deviation prevention demanded velocities). related to the front implement members computed at the excavation assistance demanded velocity calculating section <NUM> and the deviation prevention. demanded velocity calculating section <NUM>, "angular velocities" of the front implement members are computed, and thereafter the actuator control section <NUM> converts the angular velocities of the front implement members into velocities (actuator velocities) of corresponding hydraulic cylinders. However, in another configuration that can be adopted, as the velocities (excavation assistance demanded velocities and deviation prevention demanded velocities) related to the front implement members computed at the excavation assistance demanded velocity calculating section <NUM> and the deviation prevention demanded velocity calculating section <NUM>, "velocities of hydraulic cylinders" (actuator velocities) corresponding to the front implement members may be computed, and they may be output to the actuator control section <NUM>.

Note that the present invention is not limited to the embodiments described above, and includes various modification examples within the scope not deviating from the gist of the present invention. For example, the present invention is not limited to those including all the configurations explained in the embodiments described above, but also includes those from which some of the configurations are eliminated. In addition, some of configurations related to an embodiment can be added to or replaced with configurations related to another embodiment.

In addition, each configuration related to the controller described above, and the functionality, execution process and the like of each configuration may be partially or entirely realized by hardware (e.g. designing logic to execute each functionality in an integrated circuit, etc.). In addition, configurations related to the controller described above may be a program (software) that is read out/executed by a computation processing device (e.g. a CPU) to thereby realize each functionality related to the configurations of the controller. Data related to the program can be stored on, for example, a semiconductor memory (a flash memory, an SSD, etc.), a magnetic storage device (a hard disk drive, etc.), a recording medium (a magnetic disc, an optical disc, etc.), and the like.

Claim 1:
A work machine comprising:
a work implement (1A) that is attached to a machine body (1B), and has a plurality of front implement members (<NUM>, <NUM>, <NUM>) including a work tool (<NUM>);
a plurality of actuators (<NUM>, <NUM>, <NUM>, <NUM>) that drive the machine body (1B) and the plurality of front implement members (<NUM>, <NUM>, <NUM>);
an operation device that operates the plurality of actuators (<NUM>, <NUM>, <NUM>, <NUM>);
a posture sensor (<NUM>) that senses postural data about the machine body (1B) and the work implement (1A);
an operation sensor (<NUM>) that senses operation data about the operation device; and
a controller (<NUM>) that is capable of controlling the work implement (1A) by using excavation assistance control of controlling the work implement (1A) such that the work tool (<NUM>) moves along a predetermined target excavation surface (<NUM>) and deviation prevention control of preventing deviation of the work implement (1A) from a predetermined work area (<NUM>) by decelerating or stopping operation of a subject front implement member that is included in the plurality of front implement members (<NUM>, <NUM>, <NUM>) and that can deviate the work (1A) implement from the work area (<NUM>), wherein
the controller (<NUM>) is configured to control the work implement (1A) such that when the controller (<NUM>) controls the work implement (1A) by using both the excavation assistance control and the deviation prevention control, an operation direction of the work tool (<NUM>) approximates to an operation direction of the work tool (<NUM>) that is to be generated when the work implement (1A) is controlled by using only the excavation assistance control.