CONTROL DEVICE, CONTROL SYSTEM, AND CONTROL METHOD

Abstract

Provided are a control apparatus, a control system, and a control method for controlling a work machine which reduce inadvertent contact during operation of the work machine and inhibit a decrease in operating rate. A control apparatus for controlling a work machine having a movable part includes: an acquisition means of acquiring state information indicating a posture of the work machine, action information indicating an action of the work machine, and surrounding information indicating an arrangement of a surrounding object around the work machine; a specification means of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

Description

TECHNICAL FIELD

The present invention relates to a control apparatus, a control system, and a control method.

BACKGROUND ART

In recent years, utilization of robots has attracted attention as a measure for dealing with an increase in workload due to a decrease in the number of workers and a shortage of labor. For example, in the construction industry, automation of construction using autonomous construction machines is demanded in order to deal with a shortage of labor and inheritance of skills due to an aging of field workers, a decrease in young workers, and the like. However, since a construction machine is large and contact with another construction machine or equipment may develop into a major accident, it is necessary, in operation by automatic operation, to avoid contact with a structure (e.g., a dump, a column, or the like) that is not intended.

For example, Patent Literature 1 discloses a technique for slowing down or stopping a shovel in a case where the shovel has entered a forbidden region that is set with respect to an obstacle.

CITATION LIST

Patent Literature

[Patent Literature 1]

• PCT International Publication No. WO2019/189203

SUMMARY OF INVENTION

Technical Problem

In regard to the shovel disclosed in Patent Literature 1, in a case where the shovel has entered a forbidden region while the shovel is operating, there is a possibility that the shovel may come into contact with an obstacle before the shovel is controlled after sensor information is acquired and analyzed. In order to reduce such a possibility, it is conceivable that, for example, a forbidden region is set to be wider than an actual region. However, although the possibility of contact is reduced by setting a wider forbidden region, a possibility of entrance into the forbidden region increases. Therefore, it is likely that the shovel will need to be slowed down or stopped, and this may cause a decrease in operating rate.

An example aspect of the present invention is accomplished in view of the above problems, and its example object is to provide a control apparatus, a control system, and a control method for controlling a work machine which reduce inadvertent contact during operation of the work machine and inhibit a decrease in operating rate.

Solution to Problem

A control apparatus according to an example aspect of the present invention is a control apparatus for controlling a work machine having a movable part, the control apparatus including: an acquisition means of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; a specification means of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

A control system according to an example aspect of the present invention is a control system for controlling a work machine having a movable part, the control system including a control apparatus and a first sensor that acquires state information indicating a posture of the work machine, the control apparatus including: a specification means of specifying, based on the state information and action information indicating an action of the work machine, a safe distance that is set between the movable part and a surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and surrounding information indicating an arrangement of the surrounding object around the work machine.

A control method according to an example aspect of the present invention is a control method for controlling a work machine having a movable part, the control method including: acquiring state information, action information, and surrounding information by at least one processor, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; specifying, by the at least one processor and based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and controlling, by the at least one processor, an action of the work machine in accordance with the safe distance and the surrounding information.

Advantageous Effects of Invention

According to an example aspect of the present invention, it is possible to provide a control apparatus, a control system, and a control method for controlling a work machine which reduce inadvertent contact during operation of the work machine and inhibit a decrease in operating rate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of a control system according to a first example embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control apparatus according to the first example embodiment.

FIG. 3 is a flowchart illustrating a method for controlling a work machine according to the first example embodiment.

FIG. 4 is a diagram illustrating a configuration of a control system according to a second example embodiment of the present invention.

FIG. 5 illustrates an example of setting a forbidden area in a work site according to the second example embodiment.

FIG. 6 is a schematic diagram illustrating a shape of the movable part for deriving a forbidden area.

FIG. 7 is a flowchart illustrating a flow of a method for controlling a backhoe according to the second example embodiment.

FIG. 8 is a diagram illustrating a configuration of a control system according to a third example embodiment of the present invention.

FIG. 9 is a flowchart illustrating a flow of a method for controlling a backhoe according to the third example embodiment.

FIG. 10 is a configuration diagram for realizing a control apparatus by software.

EXAMPLE EMBODIMENTS

First Example Embodiment

The following description will discuss a first example embodiment of the present invention in detail with reference to the drawings. The present example embodiment is a basic form of example embodiments described later.

(Configuration of Control System)

FIG. 1 is a block diagram illustrating a configuration of a control system 1 according to the first example embodiment. The control system 1 is a control system for controlling a work machine having a movable part, and includes a control apparatus 30, and a first sensor 40 that acquires state information indicating a posture of the work machine. Specifically, the control system 1 includes: the first sensor 40 that acquires state information; a specification section 35 that specifies, based on the state information and action information indicating an action of the work machine, a safe distance which is set between the movable part of the work machine and a surrounding object; and an action control section 36 that controls an action of the work machine in accordance with the safe distance and surrounding information indicating an arrangement of the surrounding object around the work machine. The specification section 35 is configured to realize the specification means in the present example embodiment. The action control section 36 is configured to realize the action control means in the present example embodiment. The safe distance is a distance that defines a region in which each portion of a backhoe can move. Specifically, the safe distance is a desired value for carrying out control such that a distance between each portion of the backhoe and an object is not less than the safe distance. Note that the first sensor 40 and the control apparatus 30 (specification section 35 and action control section 36) may be connected to each other and communicate with each other via a wired connection or a wireless connection such as 4G, 5G (including local 5G), WiFi (registered trademark), or LTE.

In the example embodiment illustrated in FIG. 1, the specification section 35 and the action control section 36 are described as being incorporated in the single control apparatus 30. Note, however, that the specification section and the action control section 36 do not necessarily need to be incorporated in a single control apparatus. For example, the specification section 35 and the action control section 36 may be disposed in different apparatuses. The specification section 35 and the action control section 36 may be connected to each other via wired communication or wireless communication. Alternatively, the specification section 35 and the action control section 36 may be disposed on a cloud.

(Configuration of Control Apparatus)

FIG. 2 is a block diagram illustrating a configuration of the control apparatus 30 according to the first example embodiment. The control apparatus 30 includes an acquisition section 31, a safe distance specification section (specification section) 35, and the action control section 36. The acquisition section 31 acquires state information indicating a posture of the work machine, action information indicating an action of the work machine, and surrounding information indicating an arrangement of a surrounding object around the work machine. The safe distance specification section 35 specifies, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object. The action control section 36 controls an action of the work machine in accordance with the safe distance and the surrounding information. The acquisition section 31 is configured to realize the acquisition means in the present example embodiment. The safe distance specification section (specification section) 35 is configured to realize the specification means in the present example embodiment.

(Flow of Control Method)

FIG. 3 is a flowchart illustrating a method for controlling a work machine having a movable part according to the first example embodiment. In the control method, at least one processor acquires, in step S10, state information indicating a posture of the work machine, action information indicating an action of the work machine, and surrounding information indicating an arrangement of a surrounding object around the work machine. Next, in step S12, the at least one processor specifies, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object. Next, in step S14, the at least one processor controls an action of the work machine in accordance with the safe distance and the surrounding information.

According to the foregoing control apparatus, control system, and control method, it is possible to provide a control apparatus, a control system, and a control method for controlling a work machine which reduce inadvertent contact during operation of the work machine and inhibit a decrease in operating rate.

Second Example Embodiment

(Configuration of Control System)

Next, the following description will discuss a configuration of a control system 2 according to the second example embodiment with reference to the drawings. In the second example embodiment, the control system 2 in which a backhoe 100 that is operated by unmanned operation is controlled will be described as an example. FIG. 4 is a diagram illustrating the configuration of the control system 2 according to the second example embodiment of the present invention. The control system 2 includes a control apparatus 30A and a sensor 40 (first sensor, 401, 402, 403, 404). The following description will discuss the control apparatus 30 and the sensor 40 in order, and before that, the backhoe 100 will be described.

The backhoe 100 according to the present example embodiment operates based on a control instruction received from the control apparatus 30A. As illustrated in FIG. 4, the backhoe 100 includes a traveling section 10, a movable part 20 that is attached to the traveling section and a controller 80. The traveling section 10 is a traveling apparatus that allows the backhoe 100 to move forward and backward, and to turn right and left. The traveling section 10 travels, for example, with use of an endless track belt. The movable part 20 includes a rotary section 21, a boom 22 that is attached to the rotary section, an arm 23 that is attached to an end portion of the boom 22, and a bucket 24 that is attached to an end portion of the arm 23. The controller 80 controls the backhoe 100 in accordance with an action control signal received from the control apparatus 30A.

In the following descriptions, the backhoe 100 operates in accordance with an instruction by the control apparatus 30A. Note, however, that remote operation by an operator may be carried out. In addition, in a case where remote control by an operator is different from a work program or is an operation error, etc., the control apparatus 30A may modify the remote control. The control apparatus 30A may be mounted on the backhoe 100.

The rotary section 21 can turn on the traveling section 10 in a plane perpendicular to the paper surface of the drawing. Note that, in a case where the backhoe 100 is on a level ground, the plane perpendicular to the paper surface of FIG. 4 is a horizontal plane. Therefore, hereinafter, this plane is referred to as a “horizontal plane” for convenience. The boom 22 can turn and return around a boom shaft 221 in a plane that is substantially perpendicular to the horizontal plane. The arm 23 can turn and return around an arm shaft 231 on the same turning plane as that of the boom 22. The bucket 24 can turn and return around a bucket shaft 241 on the same turning plane as that of the arm 23.

The backhoe 100 is controlled by the controller 80 that has received an action control signal from the control apparatus 30A via the Internet Ni. The backhoe 100 is a work machine which moves in a predetermined work range with the traveling section 10 by unmanned operation, shovels earth and sand with the bucket 24 by operating the rotary section 21, the boom 22, and the arm 23, and transports the earth and sand to a predetermined position.

Note that the backhoe 100 may be operated by attaching an attachment to an operation lever and sending an action control signal to the attachment, instead of the case of being controlled by the controller 80. Although an example in which the controller 80 is mounted on the backhoe 100 is described in the present example embodiment, the operation method is not limited to this example. For example, a server may be disposed within a work site and an action control signal may be transmitted from the server to operate the backhoe 100. Alternatively, the server may be disposed on a cloud rather than within a work site.

(Configuration of Control Apparatus)

Next, the following description will discuss a configuration of the control apparatus 30A. As illustrated in FIG. 4, the control apparatus 30A is a control apparatus for controlling the backhoe 100 having the movable part 20, and includes the acquisition section 31, the safe distance specification section 35, the action control section 36, a storage section 38, and a communication section 39. The acquisition section 31, the safe distance specification section 35, the action control section 36, the storage section 38, and the communication section 39 are electrically connected to each other.

In the example embodiment illustrated in FIG. 4, the acquisition section 31, the safe distance specification section 35, the action control section 36, and the like are described as being incorporated in the single control apparatus 30A. Note, however, that the acquisition section 31, the safe distance specification section 35, the action control section 36, and the like do not necessarily need to be incorporated in a single control apparatus. For example, the acquisition section 31, the safe distance specification section 35, the action control section 36, and the like may be disposed separately. The acquisition section 31, the safe distance specification section 35, the action control section 36, and the like may be connected to each other via wired communication or wireless communication. Alternatively, the acquisition section 31, the safe distance specification section 35, the action control section 36, and the like may be provided on a cloud.

The acquisition section 31 includes a state information acquisition section 32 that acquires state information indicating a posture of the backhoe 100, an action information acquisition section 33 that acquires action information indicating an action of the backhoe 100, and a surrounding information acquisition section 34 that acquires surrounding information indicating an arrangement of a surrounding object 60 around the backhoe 100. The state information acquisition section 32 is configured to realize the state information acquisition means in the present example embodiment. The action information acquisition section 33 is configured to realize the action information acquisition means in the present example embodiment. The surrounding information acquisition section 34 is configured to realize the surrounding information acquisition means in the present example embodiment. The following description will discuss the sections in order.

The state information acquisition section 32 acquires, via the Internet Ni, a detection value (state information) from sensors 401, 402, 403 and 404 (collectively referred to as “first sensor 40”), which will be described later. Specifically, the detection values by the first sensors 40 are transmitted to, for example, the controller 80, and the controller 80 collectively transmits the detection values to the control apparatus 30A via the Internet Ni. Alternatively, the detection values by the first sensors 40 may be transmitted to the control apparatus directly via the Internet Ni without using the controller 80.

Furthermore, the state information acquisition section 32 derives a shape of the movable part 20 from the acquired state information. The state information of the backhoe 100 is, for example, respective turning angles of the rotary section 21, the boom 22, the arm 23, and the bucket 24. It is possible to derive the shape of the movable part 20 from these turning angles. The shape may be, for example, three-dimensional coordinates at a specific point of the movable part 20. The three-dimensional coordinates are a coordinate system identical with that of a three-dimensional map which is generated based on surrounding information (described later).

The specific point is a point at which a possibility of collision with an obstacle is high. A specific point of the movable part 20 may be, for example, an end portion of the boom 22, an end portion of the arm 23, an end portion of the bucket 24, or the like. A specific point of the traveling section 10 may be, for example, left and right front end portions and left and right rear end portions of the traveling section 10.

Note that the state information of the backhoe 100 may include position information and orientation information of the backhoe 100. The position information can be acquired with use of, for example, a global positioning system (GPS). The orientation information indicates an orientation of the traveling section 10. The orientation information can be acquired with use of an orientation sensor. Alternatively, the position information and the orientation information of the backhoe 100 may be utilized as follows: That is, an initial position, which is a stop position before starting work, and an orientation are stored in surrounding information that is stored in the storage section 38; a movement direction and a movement distance are derived from action information of the backhoe 100 after starting work; the position and the orientation at the moving destination are updated at any time; and pieces of information thus obtained are used as the position information and the orientation information.

The action information acquisition section 33 acquires action information of the backhoe 100. The action information of the backhoe 100 is, for example, information indicating a dynamic characteristic of the backhoe 100. The information indicating the dynamic characteristic includes information indicating a dynamic characteristic of the traveling section 10 or information indicating a dynamic characteristic of the movable part 20. The information indicating the dynamic characteristic is information indicating a characteristic of an action of each portion of the backhoe 100. Specifically, the information indicates, for example, whether each portion of the backhoe 100 is stopped, moving, or starting to move. In the case of moving or starting to move, the information indicates a speed, acceleration, or the like thereof. The dynamic characteristic includes, for example, at least one of a speed and acceleration of the movable part 20. Note that the speed includes an angular velocity, and the acceleration includes angular acceleration.

In a case where a speed or acceleration of an action of each portion of the backhoe 100 is high, a risk of collision with another object increases. Moreover, in a case where a speed or acceleration is high, impact by collision increases, and accordingly a risk increases. That is, the dynamic characteristic is an index indicating a risk, and it is possible to infer a risk based on the dynamic characteristic. An action of the backhoe 100 may be controlled in accordance with such a risk.

The action information such as the speed and acceleration can be acquired from a detection value from the first sensor 40. For example, in a case where the first sensor 40 can detect a speed and acceleration like an acceleration sensor, the speed and acceleration can be directly derived from detection values of the first sensor Even in a case where the first sensor 40 cannot detect a speed and acceleration, it is possible that a movement distance by which each portion of the backhoe 100 has moved per unit time is calculated from a distance of each portion of the backhoe 100 and a turning angle of each portion of the backhoe 100 that the first sensor 40 has most recently detected, and the speed and acceleration is derived from the movement distance and the unit time. Thus, it is possible to derive a speed (or angular velocity) and acceleration (or angular acceleration) of a specific point of the movable part 20 including the traveling section 10 at the three-dimensional coordinates.

The action information may be acquired, for example, from an action control signal output by the action control section 36. For example, it is possible that a speed and acceleration of movement of the traveling section 10 and each portion of the movable part 20 based on an action control signal are accumulated in a database, and the speed and acceleration of the movement of each portion are derived from the action control signal with reference to the database. The database may be prepared by observing in advance a speed and acceleration of movement of the traveling section 10 and each portion of the movable part 20 based on an action control signal. The database may include state information indicating a posture of the backhoe 100, in addition to the action control signal.

The surrounding information acquisition section 34 acquires surrounding information stored in the storage section 38 and generates a three-dimensional map. Specifically, the surrounding information is information in which position (surface) data of an object existing in a work site of the backhoe 100 is three-dimensionally recorded. The surrounding information may include a forbidden area (described later).

The safe distance specification section 35 specifies, based on the state information and the action information, a safe distance that is set between the movable part 20 and the surrounding object 60. The state information and the action information are as described above. The safe distance specification section 35 specifies a safe distance in accordance with, for example, a speed or acceleration of the movable part 20. Preferably, the safe distance specification section 35 specifies a safe distance in accordance with a speed or acceleration of the movable part 20 while taking into consideration a speed or acceleration of the traveling section 10.

The safe distance is a distance that defines a region in which each portion (e.g., a specific point) of the backhoe 100 can move. Specifically, the safe distance is a desired value for carrying out control such that a distance between each portion of the backhoe 100 and an object is not less than the safe distance. The safe distance specification section 35 changes the safe distance in accordance with action information of the backhoe 100. A specific method for deriving a safe distance will be described later.

In a case where a distance between the object 60 indicated in the surrounding information and the movable part 20 is less than the safe distance, the action control section 36 controls the movable part 20 to avoid the object Specifically, in a case where the distance between the object 60 and the movable part 20 is less than the safe distance, the action control section 36 moves the rotary section 21, the boom 22, the arm 23, or the bucket 24 to avoid collision with the object 60. A movement speed of each portion of the backhoe 100 may also be reduced. Ultimately, the action control section 36 may stop the backhoe 100.

The surrounding information is information indicating a three-dimensional arrangement of the object that exists in a work site in which the backhoe 100 carries out work. The object 60 existing in the work site is also referred to as a “surrounding object”. Note that a forbidden area 70 (described later) which has been generated based on a position of the surrounding object can also be a part of the surrounding information. In the present example embodiment, the surrounding information is stored in the storage section 38 in advance. Specifically, the surrounding information is stored in the storage section 38 before work is started. For example, the surrounding information may be input by an operator before work is started, or the surrounding information may be collected by the control apparatus 30A from a server or the like in which pieces of facility information are aggregated.

The storage section 38 may store, in addition to the foregoing surrounding information in advance, programs for the state information acquisition section 32, the action information acquisition section 33, the surrounding information acquisition section 34, the safe distance specification section 35, and the action control section 36 in a read only memory (ROM). Such programs may be loaded into RAM and executed by one or more processors of the control apparatus 30A. Thus, the programs can function as the respective sections.

The sensor (first sensor) 40 is, for example, a sensor that detects a turning angle of each of the rotary section 21, the boom 22, the arm 23, and the bucket 24. Specifically, the sensor 401 is, for example, a gyro sensor that detects a turning angle of the rotary section 21. Alternatively, the sensor 401 can be an encoder that detects the number of rotations of a motor that causes the rotary section 21 to turn. The sensor 402 is an inclination sensor or a gyro sensor that detects an angle of the boom 22 from the horizontal plane. Alternatively, the sensor 402 can be an encoder that detects a movement distance of a rod of a hydraulic cylinder that causes the boom 22 to turn. The sensor 403 is, for example, an inclination sensor, a gyro sensor, or an encoder that detects an angle of the arm 23 with respect to the boom 22. The sensor 404 is, for example, an inclination sensor, a gyro sensor, or an encoder that detects an angle of the bucket 24 with respect to the arm 23. The sensors 402 through 404 may each be disposed outside or inside the backhoe 100. In a case of being disposed outside, each of the sensors 402 through 404 is an inclination sensor, an acceleration sensor, a gyro sensor, a stroke sensor, an encoder, or the like. In a case of being disposed inside, each of the sensors 402 through 404 is a pressure sensor, a flow sensor, a cylinder sensor, a hydraulic sensor, a stroke sensor, or the like.

(Setting of Safe Distance)

Next, the following description will discuss a method for setting a safe distance by the safe distance specification section 35. First, the safe distance specification section 35 may be configured to generate a forbidden area 70 in advance based on surrounding information. The forbidden area 70 represents an object that should not be in contact with the backhoe 100 or represents, in a plane, an area where the backhoe 100 should not enter.

The forbidden area 70 may be set as a plane having a predetermined shape that surrounds the object 60. For example, as illustrated in FIG. 5, a forbidden area 70A, which is a rectangular plane, is provided around a material storage site in a work site. Further, a forbidden area 70B, which is a rectangular plane, is provided around a beam that is passed above. Note that it is not necessary to set a forbidden area 70B at a height not lower than a maximum reaching height that the movable part 20 can reach. That is, an upper limit for setting the forbidden area 70B may be up to the maximum reaching height that the movable part 20 can reach. A forbidden area 70C is provided in front of a slope region where the backhoe 100 cannot carry out work. A width and a depth of the forbidden area 70C can be set in accordance with a reachable range of the backhoe 100.

The forbidden areas 70A and 70B are restriction areas for the backhoe 100 not to make contact with the object 60 such as a material storage site or a beam. Meanwhile, the forbidden area 70C is a restriction area that restricts the backhoe 100 from entering a slope on which the backhoe 100 cannot carry out work. By thus setting predetermined planes, it is possible to provide a forbidden area not only for preventing contact but also for preventing falling.

As described above, in a case where a plane having a regular shape surrounding the object 60 is set as a forbidden area, it is possible to reduce an amount of data of the forbidden area and an amount of data and an amount of calculation necessary for setting a safe distance, and it is thus possible to increase a computation speed for obtaining a safe distance, as compared with a case where an irregular surface of the object 60 is set as a forbidden area.

The safe distance specification section 35 specifies, for example, a safe distance of a specific point of the movable part 20 based on the state information and the action information. More specifically, the safe distance specification section 35 sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part 20, and specifies the safe distance as a radius of the ellipsoid. The following description will discuss an example of specifying a safe distance between an end portion of the bucket 24 and the object 60.

FIG. 6 is a schematic diagram illustrating a shape of the movable part 20. As illustrated in FIG. 6, three-dimensional coordinates of the end portion of the bucket 24 are assumed to be (x,y,z). This three-dimensional coordinate system is identical with a three-dimensional coordinate system representing surrounding information. The three-dimensional coordinates of the end portion of the bucket 24 can be derived from state information. For example, assuming that a middle point of the boom shaft 221 is an origin of three-dimensional coordinates, each of the coordinates is expressed as in expression (1) below. Here, θ₀ represents an orientation of the backhoe 100, θ₁ represents a boom angle, θ₂ represents an arm angle, and θ₃ represents a bucket angle. The boom angle θ₁ is an angle of the boom 22 with respect to a reference plane (i.e., a turning plane of the rotary section 21), the arm angle θ₂ is an angle of the arm 23 with respect to the boom 22, and the bucket angle θ₃ is an angle of the bucket 24 with respect to the arm 23.

$\begin{array}{cc}\begin{array}{c}x=f_x\left({\theta }_0,{\theta }_1,{\theta }_2,{\theta }_3\right)\\ y=f_y\left({\theta }_0,{\theta }_1,{\theta }_2,{\theta }_3\right)\\ z=f_z\left({\theta }_0,{\theta }_1,{\theta }_2,{\theta }_3\right)\end{array}\}& \mathrm{Expression}\left(1\right)\end{array}$

The safe distance can be expressed as a variable length ellipsoid in accordance with action of the backhoe 100 or with a sensor characteristic. That is, whether or not any point (x_n, y_n, z_n) of the object 60 collides with the end portion of the bucket 24 can be calculated by the following expression (2).

$\begin{array}{cc}\frac{{\left(x_n-x\right)}^2}{a^2}+\frac{{\left(y_n-y\right)}^2}{b^2}+\frac{{\left(z_n-z\right)}^2}{c^2}\le 1& \mathrm{Expression}\left(2\right)\end{array}$

A point (x_n, y_n, z_n) at which the equality in the above expression (2) holds true forms an ellipsoid, and a point outside of the ellipsoid is determined not to collide with the end portion of the bucket 24. In the above expression (2), a, b, and c are variable numbers. By changing these numbers, it is possible to change radial distances in three axial directions (i.e., x-axis direction, y-axis direction, and z-axis direction) of the ellipsoid, respectively.

For example, the safe distance should be large in an axial direction in which a movement speed vector of the movable part 20 is large. Therefore, each of axial radii of the ellipsoid can be determined in accordance with a movement speed vector indicated in expression (3) below. The movement speed can be derived from action information.

a=f_a(v_x),b=f_b(v_y),c=f_c(v_z)  Expression (3)

In expression (3), f_a(v_x) is a function having a positive correlation that changes the variable number a in accordance with a speed v_x in the x-axis direction. That is, as the speed v_x increases, the variable number a becomes larger. Similarly, f_b(v_y) is a function having a positive correlation that changes the variable number b in accordance with a speed v_y in the y-axis direction. Moreover, f_c(v_z) is a function having a positive correlation that changes the variable number c in accordance with a speed v_z in the z-axis direction. Thus, it is possible to take a large safe distance in an axial direction in which the movement speed is high.

Further, for example, as indicated in expression (4) below, the radius of the ellipsoid can be changed in accordance with an error characteristic of the sensor 40.

$\begin{array}{cc}\begin{array}{c}{a}^{\prime }=a+l\Delta {\theta }_{3x}\\ b^{\prime }=b+l\Delta {\theta }_{3y}\\ c^{\prime }=c+l\Delta {\theta }_{3z}\end{array}\}& \mathrm{Expression}\left(4\right)\end{array}$

Expression (4) is used, in a case where an error is included in output from the sensor 404, as a calculation formula for determining a radius while taking into consideration the error. Specifically, in a case where a detected bucket angle θ₃ includes an angular error Δθ_3x in the x-axis direction, an angular error Δθ_3y in the y-axis direction, and an angular error Δθ_3z in the z-axis direction, the variable numbers a, b, and c in expression (2) are replaced with a′, b′, and c′, respectively. In expression (4), 1 is a distance from the bucket shaft 241 to the end portion of the bucket 24. Thus, even if there is an error in the sensor 404, it is possible to set a safe distance on the safe side while taking into consideration the error.

The safe distance is changed timely in accordance with state information and action information of the backhoe 100. For example, in a case where a speed of a part of the movable part 20 has changed, the safe distance specification section 35 may be set to recalculate the safe distance. Thus, in a case where the backhoe 100 is in operation, the safe distance can be recalculated and updated in a short time.

In a case where a safe distance in the three-dimensional direction is set as described above, the action control section 36 can control an action of the backhoe 100 in accordance with the set safe distance. For example, in a case where a distance between the object 60 and the end portion of the bucket 24 is less than the safe distance, the action control section 36 controls the movable part 20 to avoid the object 60. In a case where a distance between the forbidden area 70 and the end portion of the bucket 24 is less than the safe distance, the action control section 36 may control the movable part 20 to avoid the forbidden area 70.

In the above described method for specifying a safe distance, while taking into consideration a dynamic characteristic (e.g., a movement speed vector) of the backhoe 100, particularly, the movable part 20, it is possible to take a safe distance larger in a direction in which the speed is higher, and take a safe distance smaller in a direction in which the speed is lower. Therefore, the safe distance can be specified to be a necessary minimum distance.

(Configuration and Effect of Control System 2)

As described above, the control system 2 according to the second example embodiment is configured to include the control apparatus 30A for controlling the work machine (backhoe 100) having the movable part 20 and the first sensor 40 that acquires state information indicating a posture of the backhoe 100, and the control apparatus specifies, based on the state information and action information of the backhoe 100, a safe distance that is set between the movable part 20 and a surrounding object 60, and controls an action of the backhoe 100 in accordance with the safe distance and the surrounding information. Therefore, according to the control system 2 according to the second example embodiment, it is possible to reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

Note that, in a case where the distance between the object 60 and the backhoe 100 is less than the safe distance, the action control section 36 may ultimately stop the backhoe 100. In such a case, the action control section 36 may fold down the movable part 20 of the backhoe 100 to retract the movable part 20 to a safe region where there is no risk of collision, move the backhoe 100 toward another location in the work area that has been set in advance, and resume work.

(Configuration and Effect of Control Apparatus 30A)

The control apparatus 30A according to the second example embodiment includes the acquisition section that acquires state information of the backhoe 100, action information of the backhoe 100, and surrounding information indicating an arrangement of a surrounding object 60 around the backhoe 100, the specification section that specifies, based on the state information and the action information, a safe distance that is set between the movable part 20 and the surrounding object 60, and the action control section that controls an action of the backhoe 100 in accordance with the safe distance and the surrounding information. Therefore, according to the control apparatus 30A according to the second example embodiment, it is possible to reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

(Flow of Control Method)

The following description will discuss a flow of a control method S2 according to the present example embodiment with reference to FIG. 7. FIG. 7 is a flowchart illustrating the flow of the control method S2 of the backhoe 100.

First, in step S20, the surrounding information acquisition section (at least one processor) 34 acquires surrounding information indicating an arrangement of a surrounding object around the backhoe 100 from the storage section 38. Next, in step S21, the state information acquisition section (at least one processor) 32 acquires state information indicating a posture of the backhoe 100 from the sensor 40. Next, in step S22, the action information acquisition section (at least one processor) 33 acquires action information indicating an action of the backhoe 100 from the action control section 36. Next, in step S23, the safe distance specification section 35 specifies, based on the state information and the action information, a safe distance that is set between the movable part 20 of the backhoe 100 and the surrounding object 60. Next, in step S24, the action control section 36 controls an action of the backhoe 100 in accordance with the safe distance and the surrounding information. Next, in step S25, the action control section 36 determines whether or not the action control has been completed. In a case where the action control has been completed (step S25: Y), the action control ends. In a case where the action control has not been completed (step S25: N), the action control returns to step S21. The case where the action control has been completed is, for example, a case where work of the backhoe 100 has been completed, a case where the control apparatus 30A has received an instruction to complete action control, or the like.

Note that, as described above, the action information in step S22 may be information indicating a dynamic characteristic of the backhoe 100, and the dynamic characteristic includes at least one of a speed and acceleration of the movable part 20. As described above, the specifying of the safe distance in step S23 includes setting an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part 20, and specifying the safe distance as a radius of the ellipsoid. As described above, controlling of an action of the backhoe 100 in step S24 includes controlling the movable part 20 to avoid the object 60 in a case where a distance between the object 60 indicated in the surrounding information and the movable part 20 is less than the safe distance.

Note that, in a case where a shape or a movement state (whether to move or whether to turn, movement speed, acceleration, angular velocity, angular acceleration, and the like) of the backhoe 100 has changed, it is preferable that state information and action information are newly acquired, a safe distance is specified again, and action control is carried out in accordance with the new safe distance and surrounding information.

(Effect of Control Method S2)

As described above, in the control method S2 according to the present example embodiment, a configuration is employed in which the state information, the action information, and the surrounding information are acquired, the safe distance is specified based on the state information and the action information, and the action of the backhoe 100 is controlled in accordance with the safe distance and the surrounding information. Therefore, according to the control method S2 according to the present example embodiment, it is possible to reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

Third Example Embodiment

Next, the following description will discuss a third example embodiment of the present invention in detail with reference to the drawings. The same reference numerals are given to constituent elements which have functions identical with those described in the second example embodiment, and descriptions as to such constituent elements are omitted as appropriate.

FIG. 8 is a diagram illustrating a configuration of a control system 3 according to the third example embodiment of the present invention. The control system 3 according to the third example embodiment includes a control apparatus 30B and a distance sensor (second sensor) 50 that acquires distance information. The backhoe 100 which is to be controlled has a configuration identical with that of the backhoe 100 according to the second example embodiment. Therefore, descriptions thereof are omitted.

The distance sensor 50 is, for example, 3D laser imaging detection and ranging (3D Lidar) in which a position to an object is measured by a laser. The 3D Lidar is disposed at a high location in a work site, and emits laser light and measures a time until a reflected wave returns from a surrounding object 60. Note that the distance sensor 50 is not limited to the 3D Lidar, and may be a sensor that can acquire surrounding information. For example, a time of flight (ToF) camera or the like may be used. The ToF camera acquires surrounding information by emitting light and measuring a time until reflected light returns, and converting the time into a distance. The surrounding information may be acquired, for example, when the backhoe 100 is activated. The surrounding information may be acquired, for example, at a fixed time (7 o'clock, 12 o'clock, 20 o'clock, or the like) or may be acquired periodically (every 3 hours, or the like) by the distance sensor 50 that is installed in the site.

As illustrated in FIG. 8, the control apparatus 30B according to the third example embodiment includes an acquisition section 31, a safe distance specification section 35, an action control section 36, a surrounding information generation section 37, a storage section 38, and a communication section 39. The control apparatus differs from the control apparatus 30A according to the second example embodiment in that the control apparatus 30B includes the surrounding information generation section 37.

The surrounding information generation section 37 generates a three-dimensional map that includes the backhoe 100 as surrounding information based on a detection value by the distance sensor 50. Specifically, the surrounding information acquisition section 34 acquires a detection value from the distance sensor 50 and converts the detection value into a distance to the surrounding object 60. Then, the distance information is transmitted to the surrounding information generation section 37. The surrounding information generation section 37 generates surrounding information from the distance information acquired from the surrounding information acquisition section 34. The surrounding information to be generated is a three-dimensional map that includes the object 60 and the backhoe 100. The surrounding information generation section 37 can specify a position and an orientation of the backhoe 100 based on the distance information.

In a work site of the backhoe 100, materials are frequently carried in and carried out. Moreover, other work vehicles such as a truck or other work apparatuses frequently enter and leave the work site. Therefore, a position of the object 60 that is an obstacle changes from moment to moment. That is, surrounding information changes from moment to moment. In the control system 2 according to the second example embodiment described above, the surrounding information is stored in advance in the storage section 38, and cannot be updated immediately. In contrast, in the present example embodiment, the surrounding information can be timely updated to the latest information.

(Configuration and Effect of Control System 3)

As described above, in the control system 3 according to the third example embodiment, it is possible to quickly update three-dimensional surrounding information by using the distance sensor 50. Moreover, the position and orientation of the backhoe 100 can be updated quickly. Therefore, it is possible to quickly update the position of the object 60 and the position and orientation of the backhoe 100 in accordance with the state of the object 60 which changes from moment to moment and the movement of the backhoe 100. Then, from the state information and the action information, it is possible to specify the safe distance and carry out action control so as not to make contact with a newly constructed object 60. Therefore, it is possible to further reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

(Configuration and Effect of Control Apparatus 30B)

The control apparatus 30B according to the third example embodiment further includes the surrounding information generation section 37 that generates a three-dimensional map including the backhoe 100 as surrounding information based on a detection value by the distance sensor 50. Therefore, it is possible to further reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

(Flow of Control Method S3)

Next, the following description will discuss a control method S3 for controlling an action of the backhoe 100 in the control system 3 with reference to the drawings. FIG. 9 is a flowchart illustrating the flow of the control method S3 for controlling the backhoe 100 according to the third example embodiment.

First, in step S30, the surrounding information generation section 37 generates surrounding information from distance information acquired from the distance sensor (second sensor) 50. Next, in step S31, the state information acquisition section 32 acquires state information of the backhoe 100 from the sensor (first sensor) 40. The subsequent steps S32 through S35 are similar to steps S22 through S25 described above in the control method S2 of the second example embodiment. Therefore, descriptions thereof are omitted.

(Effect of Control Method S3)

In the control method S3 also, it is possible to further reduce inadvertent contact of the backhoe 100 during operation and to inhibit a decrease in operating rate.

In the foregoing second and third example embodiments, the example has been described in which the work machine is a backhoe. However, the work machine to which the present invention can be applied is not limited to that example. For example, the present invention can be applied to a machine having a movable part, such as a construction machine, an earth-moving machine, a transportation machine, a machine tool, an assembly machine, or the like. In particular, the present invention is suitably applicable to work machines in general including a robot which carry out work while changing a position.

[Software Implementation Example]

The functions of part of or all of the control apparatuses 30, 30A, and 30B can be realized by hardware such as an integrated circuit (IC chip) or can be alternatively realized by software.

In the latter case, each of the control apparatuses 30A, and 30B is realized by, for example, a computer that executes instructions of a program that is software realizing the foregoing functions. FIG. 10 illustrates an example of such a computer (hereinafter, referred to as “computer C”). The computer C includes at least one processor C1 and at least one memory C2. The memory C2 stores a program P for causing the computer C to function as the control apparatuses 30, 30A, and 30B. In the computer C, the processor C1 reads the program P from the memory C2 and executes the program P, so that the functions of the control apparatuses 30, 30A, and 30B are realized.

As the processor C1, for example, it is possible to use a central processing unit (CPU), a graphic processing unit (GPU), a digital signal processor (DSP), a micro processing unit (MPU), a floating point number processing unit (FPU), a physics processing unit (PPU), a microcontroller, or a combination of these. The memory C2 can be, for example, a flash memory, a hard disk drive (HDD), a solid state drive (SSD), or a combination of these.

Note that the computer C can further include a random access memory (RAM) in which the program P is loaded when the program P is executed and in which various kinds of data are temporarily stored. The computer C can further include a communication interface for carrying out transmission and reception of data with other apparatuses. The computer C can further include an input-output interface for connecting input-output apparatuses such as a keyboard, a mouse, a display and a printer.

The program P can be stored in a non-transitory tangible storage medium M which is readable by the computer C. The storage medium M can be, for example, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like. The computer C can obtain the program P via the storage medium M. The program P can be transmitted via a transmission medium. The transmission medium can be, for example, a communications network, a broadcast wave, or the like. The computer C can obtain the program P also via such a transmission medium.

[Additional Remark 1]

The present invention is not limited to the foregoing example embodiments, but may be altered in various ways by a skilled person within the scope of the claims. For example, the present invention also encompasses, in its technical scope, any example embodiment derived by appropriately combining technical means disclosed in the foregoing example embodiments.

[Additional Remark 2]

Some of or all of the foregoing example embodiments can also be described as below. Note, however, that the present invention is not limited to the following supplementary notes.

(Supplementary note 1)

A control apparatus for controlling a work machine having a movable part, the control apparatus including: an acquisition means of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; a specification means of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

According to the configuration, it is possible to reduce inadvertent contact during operation of the work machine and to inhibit a decrease in operating rate.

(Supplementary note 2)

The control apparatus according to supplementary note 1, in which: the action information is information indicating a dynamic characteristic of the work machine.

According to the configuration, it is possible to specify a safe distance to be shorter.

(Supplementary note 3)

The control apparatus according to supplementary note 2, in which: the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

According to the configuration, it is possible to specify a safe distance to be shorter.

(Supplementary note 4)

The control apparatus according to any one of supplementary notes 1 through 3, in which: the specification means sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifies the safe distance as a radius of the ellipsoid.

According to the configuration, it is possible to change the safe distance in accordance with each component of the speed vector.

(Supplementary note 5)

The control apparatus, further including: a surrounding information generation means of generating, as the surrounding information, a three-dimensional map that includes the work machine based on a detection value by a distance sensor.

According to the configuration, the surrounding information including the work machine can be timely updated.

(Supplementary note 6)

The control apparatus, in which: in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the action control means controls the movable part to avoid the object.

According to the configuration, it is possible to reduce inadvertent contact during operation of the work machine.

(Supplementary note 7)

A control system for controlling a work machine having a movable part, the control system including a control apparatus and a first sensor that acquires state information indicating a posture of the work machine, the control apparatus including: a specification means of specifying, based on the state information and action information indicating an action of the work machine, a safe distance that is set between the movable part and a surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and surrounding information indicating an arrangement of the surrounding object around the work machine.

According to the configuration, it is possible to reduce inadvertent contact during operation of the work machine.

(Supplementary note 8)

The control system according to supplementary note 7, in which: the action information is information indicating a dynamic characteristic of the work machine.

According to the configuration, it is possible to specify a safe distance to be shorter.

(Supplementary note 9)

The control system according to supplementary note 8, in which: the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

According to the configuration, it is possible to specify a safe distance to be shorter.

(Supplementary note 10)

The control system according to any one of supplementary notes 7 through 9, in which: the specification means sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifies the safe distance as a radius of the ellipsoid.

According to the configuration, it is possible to change the safe distance in accordance with each component of the speed vector.

(Supplementary note 11)

The control system according to any one of supplementary notes 7 through 10, further including: a second sensor for acquiring the surrounding information, the control apparatus further including a surrounding information generation means of generating a three-dimensional map that includes the work machine based on a detection value by the second sensor.

According to the configuration, the surrounding information including the work machine can be timely updated.

(Supplementary note 12)

The control system according to any one of supplementary notes 7 through 11, in which: in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the action control means controls the movable part to avoid the object.

According to the configuration, it is possible to reduce inadvertent contact during operation of the work machine.

(Supplementary note 13)

A control method for controlling a work machine having a movable part, the control method including: acquiring state information, action information, and surrounding information by at least one processor, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; specifying, by the at least one processor and based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and controlling, by the at least one processor, an action of the work machine in accordance with the safe distance and the surrounding information.

According to the method, it is possible to reduce inadvertent contact during operation of the work machine and to inhibit a decrease in operating rate.

(Supplementary note 14)

The control method according to supplementary note 13, in which: the action information is information indicating a dynamic characteristic of the work machine.

According to the method, it is possible to specify a safe distance to be shorter.

(Supplementary note 15)

The control method according to supplementary note 14, in which: the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

According to the method, it is possible to specify a safe distance to be shorter.

(Supplementary note 16)

The control method according to any one of supplementary notes 13 through 15, in which: the specifying of the safe distance includes setting an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifying the safe distance as a radius of the ellipsoid.

According to the method, it is possible to change the safe distance in accordance with each component of the speed vector.

(Supplementary note 17)

The control method according to any one of supplementary notes 13 through 16, in which: the acquiring of the surrounding information includes generating, as the surrounding information, a three-dimensional map that includes the work machine based on a detection value by a distance sensor.

According to the method, the surrounding information including the work machine can be timely updated.

(Supplementary note 18)

The control method according to any one of supplementary notes 13 through 17, in which: the controlling of the action of the work machine includes, in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, controlling the movable part to avoid the object.

According to the method, it is possible to reduce inadvertent contact during operation of the work machine.

(Supplementary note 19)

A program for causing a computer to function as a control apparatus for controlling a work machine having a movable part, the program causing the computer to function as: an acquisition means of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; a specification means of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

According to the configuration, an effect similar to that of supplementary note 1 is brought about.

(Supplementary note 20)

The program according to supplementary note 19, in which: the action information is information indicating a dynamic characteristic of the work machine.

According to the configuration, an effect similar to that of supplementary note 2 is brought about.

(Supplementary note 21)

The program according to supplementary note 20, in which: the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

According to the configuration, an effect similar to that of supplementary note 3 is brought about.

(Supplementary note 22)

The program according to any one of supplementary notes 19 through 21, in which: the specification means sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifies the safe distance as a radius of the ellipsoid.

According to the configuration, an effect similar to that of supplementary note 4 is brought about.

(Supplementary note 23)

The program according to any one of supplementary notes 19 through 22, further including: a surrounding information generation means of generating, as the surrounding information, a three-dimensional map that includes the work machine based on a detection value by a distance sensor.

According to the configuration, an effect similar to that of supplementary note 5 is brought about.

(Supplementary Note 24)

The program according to any one of supplementary notes 19 through 23, in which: in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the action control means controls the movable part to avoid the object.

According to the configuration, an effect similar to that of supplementary note 6 is brought about.

(Supplementary Note 25)

A computer-readable non-transitory tangible storage medium storing a program for causing a computer to function as a control apparatus for controlling a work machine having a movable part, the program causing the computer to function as: an acquisition means of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; a specification means of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and an action control means of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

(Supplementary Note 26)

A control apparatus for controlling a work machine having a movable part, the control apparatus including at least one processor, the at least one processor carrying out: a process of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine; a process of specifying, based on the state information and the action information, a safe distance that is set between the movable part and the surrounding object; and a process of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

Note that the control apparatus can further include a memory. In the memory, a program for causing the processor to execute the above processes can be stored.

REFERENCE SIGNS LIST

• • 1, 2, 3: Control system
  • 10: Traveling section
  • 20: Movable part
  • 21: Rotary section
  • 22: Boom
  • 23: Arm
  • 24: Bucket
  • 30, 30A, 30B: Control apparatus
  • 31: Acquisition section (acquisition means)
  • 32: State information acquisition section (state information acquisition means)
  • 33: Action information acquisition section (action information acquisition means)
  • 34: Surrounding information acquisition section (surrounding information acquisition means)
  • 35: Safe distance specification section (safe distance specification means)
  • 36: Action control section (action control means)
  • 37: Surrounding information generation section (surrounding information generation means)
  • 38: Memory
  • 39: Communication means
  • 40 (401, 402, 403, 404): Sensor (first sensor)
  • 50: Distance sensor (second sensor)
  • 60: Object
  • 70 (70A, 70B, 70C): Forbidden area
  • 80: Controller
  • 100: Backhoe

Claims

1. A control apparatus for controlling a work machine, said control apparatus comprising at least one processor, the at least one processor carrying out:

an acquisition process of acquiring state information, action information, and surrounding information, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine;

a specification process of specifying, based on the state information and the action information, a safe distance that is set between a movable part of the work machine and the surrounding object; and

an action control process of controlling an action of the work machine in accordance with the safe distance and the surrounding information.

2. The control apparatus according to claim 1, wherein:

the action information is information indicating a dynamic characteristic of the work machine.

3. The control apparatus according to claim 2, wherein:

the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

4. The control apparatus according to claim 1, wherein:

in the specification process, the at least one processor sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifies the safe distance as a radius of the ellipsoid.

5. The control apparatus according to claim 1, wherein:

the at least one processor further carries out a surrounding information generation process of generating, as the surrounding information, a three-dimensional map that includes the work machine based on a detection value by a distance sensor.

6. The control apparatus according to claim 1, wherein:

in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the at least one processor controls, in the action control process, the movable part to avoid the object.

7. A control system for controlling a work machine, said control system comprising a control apparatus and a first sensor that acquires state information indicating a posture of the work machine,

the control apparatus including at least one processor, the at least one processor carrying out:

a specification process of specifying, based on the state information and action information indicating an action of the work machine, a safe distance that is set between a movable part of the work machine and a surrounding object; and

an action control process of controlling an action of the work machine in accordance with the safe distance and surrounding information indicating an arrangement of the surrounding object around the work machine.

8. The control system according to claim 7, wherein:

the action information is information indicating a dynamic characteristic of the work machine.

9. The control system according to claim 8, wherein:

the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

10. The control system according to claim 7, wherein:

in the specification process, the at least one processor sets an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and specifies the safe distance as a radius of the ellipsoid.

11. The control system according to claim 7, further comprising:

a second sensor for acquiring the surrounding information,

the at least one processor further carrying out a surrounding information generation process of generating a three-dimensional map that includes the work machine based on a detection value by the second sensor.

12. The control system according to claim 7, wherein:

in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the at least one processor controls, in the action control process, the movable part to avoid the object.

13. A control method for controlling a work machine, said control method comprising:

acquiring state information, action information, and surrounding information by at least one processor, the state information indicating a posture of the work machine, the action information indicating an action of the work machine, and the surrounding information indicating an arrangement of a surrounding object around the work machine;

specifying, by the at least one processor and based on the state information and the action information, a safe distance that is set between a movable part of the work machine and the surrounding object; and

controlling, by the at least one processor, an action of the work machine in accordance with the safe distance and the surrounding information.

14. The control method according to claim 13, wherein:

the action information is information indicating a dynamic characteristic of the work machine.

15. The control method according to claim 14, wherein:

the dynamic characteristic includes at least one of a speed and acceleration of the movable part.

16. The control method according to claim 13, wherein:

the specifying of the safe distance includes

setting an ellipsoid having axial radii corresponding to respective components of a speed vector of the movable part, and

specifying the safe distance as a radius of the ellipsoid.

17. The control method according to claim 13, wherein:

the acquiring of the surrounding information includes generating, as the surrounding information, a three-dimensional map that includes the work machine based on a detection value by a distance sensor.

18. The control method according to claim 13, wherein:

in a case where a distance between the object indicated in the surrounding information and the movable part is less than the safe distance, the controlling of the action of the work machine includes controlling the movable part to avoid the object.

19. A computer-readable non-transitory tangible storage medium storing a program for causing a computer to carry out the acquisition process, the specification process, and the action control process which are recited in claim 1.