AUTONOMOUS WORK EXCAVATOR AND OPERATION METHOD THEREOF

Abstract

Embodiments disclosed herein relate to an autonomous work excavator and an operation method therefor. According to an embodiment, an excavator comprises a front work device including an arm, a boom, and a bucket; a sensor device configured to collect state information of the excavator and information related to the surrounding environment; and a processor electrically connected to the front work device and the sensor device. The processor is configured to perform a digging operation based on a work instruction such that soil is loaded in the bucket; calculate a zero-moment point of a force acting on the excavator based on mass information on at least a portion of the front work device after the digging operation has been performed; and obtain a work trajectory for processing the soil loaded in the bucket by using the ZMP and the information related to surrounding environment.

Description

TECHNICAL FIELD

Various embodiments of the present disclosure relate to an autonomous work excavator and an operation method thereof which prevent an excavator from tipping over (and/or overturning), and more specifically, an autonomous work excavator and an operation method thereof which generate a work trajectory based on a zero-moment point (ZMP) and control operation according to the generated work trajectory.

BACKGROUND

Due to the harsh and dangerous environment of a construction site, research on autonomous work construction machines that are automatically controlled using control algorithms rather than manual operation by workers is being actively conducted.

FIG. 1 is a diagram illustrating a system (e.g., an autonomous work system) 100 enabling conventional autonomous work.

Referring to FIG. 1, an autonomous work system 100 may include a control center 110 and at least one construction machine (or autonomous work construction machine) 120 to 150.

The construction machines 120 to 150 are machines that conduct autonomous work at civil engineering or construction sites, such as a mixer truck 120, a dump truck 130, a bulldozer 140, and an excavator 150.

These construction machines may conduct autonomous work according to work instructions received from the control center 110. For example, the excavator 150 receiving the work instruction recognizes surrounding environment and determines a work trajectory along which the tip of the bucket or arm is to move in order to conduct an operation (e.g., digging (or excavation) operation).

However, the conventional excavator 150 limits the speed and acceleration of each joint of the excavator 150 and generates a work trajectory that minimizes the moving time of the excavator 150 in a limited situation. In other words, since the posture, excavation amount, topography, or the like of the excavator 150 are not taken into consideration in generating the work trajectory, there may occur an accident in which the main body of the excavator 150 tilts or overturns and/or tips over when the excavator works on uneven terrain or inclined terrain.

DISCLOSURE

Technical Problem

The technical task to be solved by the present disclosure is to provide an excavator and an operation method therefor which enable autonomous work to be conducted.

An object to be solved by the present disclosure is to provide an excavator and an operation method therefor which generate a work trajectory based on a zero-moment point (ZMP).

The technical tasks to be achieved in the present disclosure are not limited to the technical tasks mentioned above, and other technical tasks not mentioned can be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below.

Technical Solution

According to various embodiments of the present disclosure, an excavator includes a front work device including an arm, a boom, and a bucket, a sensor device configured to collect state information of the excavator and information related to surrounding environment, and a processor electrically connected to the front work device and the sensor device, wherein the processor may perform a digging operation such that soil is loaded in the bucket based on a work instruction, calculate a zero-moment point (ZMP) of a force acting on the excavator based on mass information on at least a portion of the front work device after the digging operation has been performed, and obtain a work trajectory for processing the soil loaded in the bucket by using the ZMP and the information related to surrounding environment.

According to various embodiments of the present disclosure, an operation method of an excavator includes performing a digging operation based on a work instruction, calculating a zero-moment point (ZMP) of a force acting on the excavator based on mass information on at least a portion of a front work device including an arm, a boom, and a bucket after the digging operation has been performed, obtaining a work trajectory for processing soil loaded in the bucket using the ZMP, and performing a rotation operation of moving the bucket from a digging point to a vicinity of a loading container according to the work trajectory.

Advantageous Effect

The excavator according to embodiments of the present disclosure may effectively prevent the excavator from tipping over and/or overturning during operation by generating a work trajectory based on a zero-moment point (ZMP).

The effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the description below.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a conventional system enabling autonomous work.

FIG. 2A is a diagram for describing an autonomous work excavator according to various embodiments.

FIG. 2B is a diagram for describing a sensor provided in an autonomous work excavator according to various embodiments.

FIG. 3 is a conceptual diagram illustrating an autonomous work excavator according to various embodiments of the present disclosure.

FIGS. 4A and 4B are views for describing an optimal rotation trajectory of an autonomous work excavator according to various embodiments.

FIGS. 5A to 5E are views for describing an optimal rotation trajectory for collision avoidance of an autonomous work excavator according to various embodiments.

FIGS. 6A to 6E are views for describing an optimal dumping trajectory of an autonomous work excavator according to various embodiments.

FIG. 7 is a flowchart of a method of operating an autonomous work excavator according to various embodiments.

FIG. 8 is a flowchart of a method of processing a subsequent operation in an autonomous work excavator according to various embodiments.

FIG. 9 is a flowchart of a method of regenerating a trajectory in an autonomous work excavator according to various embodiments.

FIG. 10 is a flowchart of a method of conducting a dumping operation in an autonomous work excavator according to various embodiments.

MODE FOR INVENTION

The features, advantages and method for accomplishment of the present disclosure will be more apparent from referring to the following detailed embodiments described as well as the accompanying drawings. However, the present disclosure is not limited to embodiments disclosed below, but will be implemented in various different forms, and these embodiments are merely provided so that this disclosure will be complete, and will fully convey the scope of the invention to those skilled in the art and the present disclosure is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

What one component is referred to as being “connected to” or “coupled to” another component includes both a case where one component is directly connected or coupled to another component and a case where a further another component is interposed between them. Meanwhile, what one component is referred to as being “directly connected to” or “directly coupled to” another component indicates that a further another component is not interposed between them. The term “and/or” includes each of the mentioned items and one or more all of combinations thereof.

Terms used in the present specification are provided for description of only specific embodiments of the present disclosure, and not intended to be limiting. In the present specification, an expression of a singular form includes the expression of plural form thereof if not specifically stated. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, do not preclude the presence or addition of one or more other components, steps, operations, and/or elements.

While terms such as the first and the second, etc., can be used to describe various components, the components are not limited by the terms mentioned above. The terms are used only for distinguishing between one component and other components.

Therefore, the first component to be described below may be the second component within the spirit of the present disclosure. Unless differently defined, all terms used herein including technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Also, commonly used terms defined in the dictionary should not be ideally or excessively construed as long as the terms are not clearly and specifically defined in the present application.

A term “part” or “module” used in the embodiments may mean software components or hardware components such as a field programmable gate array (FPGA), an application specific integrated circuit (ASIC). The “part” or “module” performs certain functions. However, the “part” or “module” is not meant to be limited to software or hardware. The “part” or “module” may be configured to be placed in an addressable storage medium or to restore one or more processors. Thus, for one example, the “part” or “module” may include components such as software components, object-oriented software components, class components, and task components, and may include processes, functions, attributes, procedures, subroutines, segments of a program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. Components and functions provided in the “part” or “module” may be combined with a smaller number of components and “parts” or “modules” or may be further divided into additional components and “parts” or “modules”.

Methods or algorithm steps described relative to some embodiments of the present disclosure may be directly implemented by hardware and software modules that are executed by a processor or may be directly implemented by a combination thereof. The software module may be resident on a RAM, a flash memory, a ROM, an EPROM, an EEPROM, a resistor, a hard disk, a removable disk, a CD-ROM, or any other type of record medium known to those skilled in the art. An exemplary record medium is coupled to a processor and the processor can read information from the record medium and can record the information in a storage medium. In another way, the record medium may be integrally formed with the processor. The processor and the record medium may be resident within an application specific integrated circuit (ASIC). The ASIC may reside in a user terminal.

FIG. 2A is a diagram for describing an autonomous work excavator according to various embodiments of the present disclosure. Further, FIG. 2B is a diagram for describing a sensor provided in the autonomous work excavator. In the following description, an excavator is described as a construction machine, but the embodiment of the present disclosure is not limited to the excavator and may be applied to various construction machines. In addition, the following embodiments of the present disclosure may be applicable to an excavator which a worker is capable of manual operation.

Referring to FIG. 2A, the autonomous work excavator 200 (hereinafter referred to as the excavator 200) may include a lower body 210 that serves as a mobility, an upper body 220 mounted on the lower body 210 and rotating 360 degrees and a front work device 230 coupled to the front of the upper body 220. However, this is merely an example, and embodiments of the present disclosure are not limited thereto. For example, one or more other components (e.g., a plate coupled to the rear of the lower body 210) may be added in addition to the components of the excavator 200 described above.

According to various embodiments, the upper body 220 may include an interior space (not shown) in which a cab 222 in which a driver rides and operates is positioned and on which a power generating device (e.g., an engine) is mounted. The cab 222 may be provided in a portion close to a work area. The work area is a space in which the excavator 200 works and is located in the front of the excavator 200. For example, in consideration of a position where the driver on board perform operation with a secured field of view and the front work device 230 is mounted, the cab 222 may be located at a position which is close to the work area as shown in FIG. 2A and the upper body 220 and is deflected to one side in the upper body 220.

According to various embodiments, the front work device 230 is mounted on the top of the upper body 220 and may be a device for performing operation such as digging land or transporting an object having a large load. According to one embodiment, the front work device 230 may include a boom 231 rotatably coupled to the upper body 220, a boom cylinder 232 configured to rotate the boom 231, an arm 233 rotatably coupled to the front end of the boom 231, an arm cylinder 234 configured to rotating the arm 233, a bucket 235 rotatably coupled to the front end of the arm 233, and a bucket cylinder 236 configured to rotating bucket 235. During the operation of the excavator 200, one end of the boom 231, one end of the arm 233, and one end of the bucket 235 may individually rotate to maximize the reachable area of the bucket 235. Since the above-described front work device 230 is known from many documents, a detailed description thereof will be omitted.

According to various embodiments, the lower body 210 may be coupled to the bottom of the upper body 220. The lower body 210 may include a traveling body formed in a wheel type using wheels or a crawler type using caterpillars. The traveling body may implement forward, backward, left and right movements of the excavator 200 by using power generated by the power generating device as a driving power. According to one embodiment, the lower body 210 and the upper body 220 may be rotatably coupled by a center joint.

According to various embodiments, the excavator 200 may perform unmanned automation, that is, autonomous operation, and may include a plurality of sensors.

According to one embodiment, the plurality of sensors may include a first sensor for detecting a state of the excavator 200 For example, the state of the excavator 200 may include a rotational state of the upper body 220 (or lower body 210). The first sensor may be disposed at a center joint to detect the rotational state of the upper body 220. In addition, the state of the excavator 200 may include a rotational state of the front work device 230. The first sensor may be disposed on each of the boom 231, the arm 233, and the bucket 235, or may be disposed on the joint (e.g., hinge connection) of the boom 231, the arm 233, and the bucket 235 to detect at least a rotational state of each of the boom 231, the arm 233, and the bucket 235. The position of the above-described first sensor is an example, and the present disclosure is not limited thereto, and the first sensor may be disposed at various locations at which the first sensor is able to detect a state of the excavator 200.

According to one embodiment, a plurality of sensors may include a second sensor for detecting a work area in which the excavator 200 is capable of operating. As described above, the work area is a space where the excavator is able to operate and may be located in front of the excavator 200. The second sensor may be disposed in a portion of the upper body 220 close to the work area, for example, on one side of the upper surface of the cab 222 close to the front work device 230 to detect the work area. However, this is merely an example, and the position of the second sensor is not limited thereto. For example, the second sensor may be disposed on the front work device 230, for example, the arm 233 or the bucket 235 to additionally or selectively detect the work area.

According to one embodiment, the plurality of sensors may include a third sensor for detecting an obstacle around the excavator 200. The third sensor may be disposed at the front, side, and rear of the upper body 220 to detect an obstacle around the excavator 200. The position of the above-described third sensor is an example, and the present disclosure is not limited thereto, and the third sensor may be disposed at various locations at which the third sensor is able to detect an obstacle around the excavator 200.

According to various embodiments, the various sensors described above may include an angle sensor, an inertial sensor, a rotation sensor, an electromagnetic wave sensor, a camera sensor, a radar, a LiDAR, an ultrasonic sensor or the like. For example, the first sensor may include at least one of an angle sensor, an inertial sensor, and a rotation sensor, and each of the second and third sensors may include at least one of an electromagnetic wave sensor, a camera sensor, a radar, a LiDAR, or an ultrasonic sensor. For example, as indicated by reference numeral 240 in FIG. 2B, a camera sensor disposed on the upper surface of the cab 222 or the arm 233 of the excavator 200 may be used as the second sensor. In addition, a LiDAR disposed on the front of the excavator 200 as indicated by reference numeral 250 in FIG. 2B, ultrasonic sensors disposed on the side and rear surface of the excavator 200 as indicated by reference numeral 260 in FIG. 2B, camera sensors disposed on the front, side, and rear of the excavator 200 as indicated by reference numeral 270 in FIG. 2B, may be used as the third sensor. Additionally, or alternatively, when the image sensor is used as the second sensor and the third sensor, the image sensor may be configured as a stereo vision system capable of obtaining an image from which a distance to an object is able to be obtained.

In addition, each of the first sensor, the second sensor, and the third sensor may perform the same or similar operation as the other sensors. For example, by using the third sensor for detecting an obstacle around the excavator 200, the operation of the second sensor for detecting the work area in which the excavator 200 is operating may be performed.

According to various embodiments, the excavator 200 may perform unmanned automation, that is, autonomous operation, and may include at least one positioning device.

According to an embodiment, a global navigation satellite system (GNNS) module capable of receiving a satellite signal may be used as the positioning device, and a real time kinematic (RTK) GNSS module may be used for precise measurement. For example, at least one positioning device may be disposed on the upper body 220 of the excavator 200.

FIG. 3 is a diagram conceptually illustrating an autonomous work excavator 300 according to various embodiments of the present disclosure. FIGS. 4A and 4B are views for describing an optimal rotation trajectory of the autonomous work excavator 300 according to various embodiments of the present disclosure, FIGS. 5A to 5E are views for describing an optimal rotation trajectory for collision avoidance of an autonomous work excavator 300 according to various embodiments of the present disclosure, and FIGS. 6A to 6E are views for describing an optimal dumping trajectory of the autonomous work excavator 300 according to various embodiments of the present disclosure.

Referring to FIG. 3, an autonomous work excavator 300 (hereinafter, referred to as an excavator 300) may include a processor 310, a communication device 320, a storage device 330, a sensor device 340, and a work control device 350. However, this is merely an example, and embodiments of the present disclosure are not limited thereto. For example, at least one of the above-described components of the excavator 300 may be omitted or one or more other components (e.g., an input device, an output device, or the like) may be added to the excavator 300.

According to various embodiments, the processor 310 may be configured to control overall operation of the excavator 300. According to one embodiment, the processor 310 may execute software (e.g., a program) stored in the storage device 330 to control at least one of components connected to the processor 310 (e.g., the communication device 320, the storage device 330, the sensor device 340, or the work control device 350) and perform various data processing or operations. For example, as at least a part of data processing or operation, the processor 310 may store instructions or data received from other components in the storage device 330, process the instructions or data stored in the storage device 330, and store result data in the storage device 330. The processor 310 may be composed of a main processor and an auxiliary processor capable of being operated independently of or together with the main processor. According to one embodiment, the processor 310 may perform CAN (Controller Area Network) communication with the aforementioned component (e.g., the communication device 320, the storage device 330, the sensor device 340, or the work control device 350) but the present disclosure is not limited thereto.

According to various embodiments, the communication device 320 may transmit/receive data to/from an external device using wireless communication technology. The external device may include control centers and other construction machinery. For example, the communication device 320 may receive a work instruction from an external device and transmit work-related information (e.g., work result) to the external device. In this case, the communication technology used by the communication device 320 may include GSM (Global System for Mobile communication), CDMA (Code Division Multi Access), LTE (Long Term Evolution), 5G, WLAN (Wireless LAN), Wi-Fi (Wireless-Fidelity), Bluetooth™, RFID (Radio Frequency Identification), Infrared Data Association (IrDA), ZigBee, NFC (Near Field Communication), and the like. Also, the communication device 320 may include at least one positioning device (e.g., GNNS, RTK GNSS, or the like) as described above with reference to FIG. 2.

According to various embodiments, the storage device 330 may store various data used by at least one component of the excavator 300 (e.g., the processor 310, the communication device 320, the sensor device 340, or the work control device 350). According to one embodiment, the storage device 330 may store an algorithm for generating a work trajectory, specifications of the excavator 300 (e.g., model name, serial number, basic specifications), map data, and the like. For example, the storage device 330 may include at least one of a non-volatile memory device and a volatile memory device.

According to various embodiments, the sensor device 340 may collect information related to at least one of a state of the excavator 300, a work area of the excavator 300, or a surrounding obstacle of the excavator 300 using various sensors. As described above with reference to FIG. 2, the sensor device 340 may include a first sensor, a second sensor, and a third sensor. For example, at least one of an angle sensor, an inertial sensor, or a rotation sensor for collecting information related to the state of the excavator 300 may be used as a configuration of the sensor device 340, and at least one of an electromagnetic wave sensor, a camera sensor, a radar, a LiDAR, and an ultrasonic sensor for collecting information related to the surrounding environment of the excavator 300 (e.g., a work area and a surrounding obstacle) may be used as a component of the sensor device 340. However, this is merely an example, and embodiments of the present disclosure are not limited thereto. For example, various types of sensors capable of collecting information related to the state of the excavator 300, the work area of the excavator 300, or a surrounding obstacle of the excavator 300 may be used as the component of the sensor device 340.

According to various embodiments, the work control device 350 may control an operation of the excavator 300. For example, the work control device 350 may include a work planning unit 352 and a driving control unit 354.

According to various embodiments, the work control device 350 may receive a work instruction from an external device.

According to an embodiment, the work instruction may include a work area and a type of operation (or operation contents) to be performed in the work area. The type of operation may include a digging operation, a trench operation, a grading operation, a breaking operation, a dumping operation for loading excavated soil, a swing operation for rotating the upper body 220 and a moving operation for changing a position of the excavator 300. Also, the work area is a portion of a work area and may be an area where at least one operation is to be performed (e.g., a digging operation, a grading work, or the like). Additionally, the work instruction may include a movement path for guiding the excavator 300, which is out of the work area and then waits for, to the work area. In this case, the excavator 300 may leave a waiting area and move to the work area based on the movement path.

According to various embodiments, the work control device 350 (or the work planning unit 352) may obtain (or generate) a work trajectory for performing an operation based on a work instruction. The work trajectory may be a trajectory on which at least a portion of the front working device 230 (e.g., the front end of the bucket 235 or the arm 233) needs to move. For example, the work control device 350 (or the work planning unit 352) may obtain a digging trajectory for performing a digging operation, a rotation trajectory for performing a rotation operation, and a dumping trajectory for performing a dumping operation.

According to various embodiments, the digging trajectory may be obtained based on a digging start position, a digging end position, an angle of the bucket 235, a movement amount of the bucket 235, or the like. In addition, when the digging trajectory is obtained, the work control device 350 (or the driving control unit 354) may control the front work device 230 to perform a digging operation according to the digging trajectory.

According to various embodiments, the rotation trajectory may be obtained based on a rotation start position, a rotation end position, a height of a dumping point, a rotation amount to a dumping point, or the like. In addition, when the rotation trajectory is obtained, the work control device 350 (or the driving control unit 354) may control the front work device 230 to perform a rotation operation according to the rotation trajectory.

In this case, the work control device 350 (or the work planning unit 352) may generate an optimal rotation trajectory so as to enable movement according to the rotation trajectory in a minimum time. For example, the work control device 350 (or the work planning unit 352) may determine a path parameter value according to time by applying a path parameterization function to a rotation trajectory. The path parameter may be defined as in Equation 1 below.

$\begin{array}{cc}s\left(0\right)=0\le s\left(t\right)\le 1=s\left(T\right)& \left[\mathrm{Equation}1\right]\end{array}$ $\stackrel{.}{s}\ge 0\mathrm{where}\mathrm{for}t\in \left[0,T\right]$

In addition, for trajectory optimization, an optimization variable may be defined as shown in Equation 2 below, and an optimal rotation trajectory may be formulated as shown in Equation 3 below using Equation 2.

$\begin{array}{cc}\alpha \left(s\right)=\ddot{s}& \left[\mathrm{Equation}2\right]\end{array}$ $\beta \left(s\right)={\stackrel{.}{s}}^2$ ${\beta }^{\prime }\left(s\right)=2\alpha \left(s\right)$ $\stackrel{.}{\beta }\left(s\right)=2\alpha \left(s\right)\stackrel{.}{s}$ $\begin{array}{cc}\underset{\alpha ,\beta }{\min }{\int }_0^1\frac{1}{\sqrt{\beta \left(s\right)}}\mathrm{ds}& \left[\mathrm{Equation}3\right]\end{array}$ $\mathrm{subject}\mathrm{to}\beta \left(0\right)={\stackrel{.}{s}}_0^2$ $\beta \left(1\right)={\stackrel{.}{s}}_T^2$ ${\beta }^{\prime }\left(s\right)=2\alpha \left(s\right)$ $\beta \left(s\right)\ge 0$ $❘{\stackrel{.}{q}}_i❘\le c_i$

Additionally, the work control device 350 (or the work planning unit 352) may consider a zero-moment point (ZMP) to obtain an optimal rotation trajectory in order to prevent the excavator 300 from overturning (and/or tipping over). The ZMP may refer to a point where a moment on the z axis remains alone and moments on the x and y axes are zero. For example, when the ZMP is located within a supporting polygon, which is the minimum polygon of the ground surface which the lower body (e.g., the lower body 210) of the excavator 300 is in contact with, the excavator 300 may be in a state capable of stable work. On the other hand, when the ZMP is out of the supporting polygon, there may be a possibility that the excavator 300 overturns.

For example, the ZMP may be derived based on a mass (m) applied to at least a portion (e.g., the boom 231, the arm 233 or the bucket 235) of the front work device 230 as shown in Equation 4 below. In order to obtain an optimal rotation trajectory in consideration of the ZMP, as shown in Equation 5 below, the joints of the front work device 230 (e.g., the bucket (235) joint, the arm (233) joint, or the boom (231) joint) are defined as functions for the path parameterization function, and as shown in Equation 6 below, a center of mass and acceleration of each link are expressed as a function for the joint of the front work device 230 using the kinematic information of the excavator 300, so that terms required for derivation of the ZMP may be organized.

$\begin{array}{cc}\sum _i\left(r_i-p\right)\times m_i\left({\ddot{r}}_i+g\right)+\sum _i{T}_i=M_p=[\begin{array}{ccc}0& 0& {M_z]}^T\end{array}& \left[\mathrm{Equation}4\right]\end{array}$ $\mathrm{where}{T}_i=I_i·{\stackrel{.}{w}}_i+w_i\times I_i·w_i$ $r_i=[\begin{array}{ccc}{x}_i& y_i& {z_i]}^T:\mathrm{COM}\mathrm{of}i-\mathrm{th}\mathrm{link}\end{array}$ $x_{\mathrm{zmp}}=\frac{{\sum }_i{m}_i\left({\ddot{z}}_i+g\right)x_i-{\sum }_i{m}_i{\ddot{x}}_i{z}_i-{\sum }_i{\left(T_y\right)}_i}{{\sum }_i{m}_i\left({\ddot{z}}_i+g\right)}$ $y_{\mathrm{zmp}}=\frac{{\sum }_i{m}_i\left({\ddot{z}}_i+g\right)y_i-{\sum }_i{m}_i{\ddot{y}}_i{z}_i-{\sum }_i{\left(T_x\right)}_i}{{\sum }_i{m}_i\left({\ddot{z}}_i+g\right)}$ $\begin{array}{cc}q=q\left(s\right),\stackrel{.}{q}=q_s\stackrel{.}{s},\ddot{q}=q_s\ddot{s}+q_{\mathrm{ss}}{\stackrel{.}{s}}^2& \left[\mathrm{Equation}5\right]\end{array}$ $\begin{array}{cc}{p}_i=[\begin{array}{ccc}{x}_i& y_i& {z_i]}^T:\mathrm{COM}\mathrm{of}i-\mathrm{th}\mathrm{link}\end{array}& \left[\mathrm{Equation}6\right]\end{array}$ $p_i=r^p\left(q\right)$ ${\stackrel{.}{p}}_i=r_q^p\stackrel{.}{q}$ ${\ddot{p}}_i=r_q^p\ddot{q}+{\stackrel{.}{q}}^T{r}_{\mathrm{qq}}^p\stackrel{.}{q}$ ${\omega }_i=r^{\omega }\left(q\right)\stackrel{.}{q}$ ${\stackrel{.}{\omega }}_i=r^{\omega }\ddot{q}+q^T{r}_q^{\omega }\stackrel{.}{q}$ $T_i=I_i\left(r^{\omega }\ddot{q}+{\stackrel{.}{q}}^T{r}_q^{\omega }\stackrel{.}{q}\right)+\left(r^{\omega }\stackrel{.}{q}\right)\times I_i{r}^{\omega }\stackrel{.}{q}$ $\begin{array}{c}\to {\ddot{p}}_i=\left(r_q^p{q}_s\right)\ddot{s}+\left(r_q^p{q}_{\mathrm{ss}}+q_s^T{r}_{\mathrm{qq}}^p{q}_s\right){\stackrel{.}{s}}^2\\ =p_{i_1}\ddot{s}+p_{i_2}{\stackrel{.}{s}}^2\end{array}$ $\begin{array}{c}\to T_i=\left(I_i{r}^{\omega }{q}_s\right)\ddot{s}+\left[I_i\left(r^{\omega }{q}_{\mathrm{ss}}+q_s^T{r}_q^{\omega }{q}_s\right)+\left(r^{\omega }{q}_s\right)\times I_i\left(r^{\omega }{q}_s\right)\right]{\stackrel{.}{s}}^2\\ =T_{i_1}\ddot{s}+T_{i_2}{\stackrel{.}{s}}^2\end{array}$

In addition, a function for *** may be arranged as shown in Equation 7 below using the function defined through Equation 5 and the terms organized through Equation 6, and the optimal rotation trajectory may be formulated as shown in Equation 8 below.

$\begin{array}{cc}{x}_{\mathrm{ZMP}}=\frac{a_x\left(s\right)\ddot{s}+b_x\left(s\right){\stackrel{.}{s}}^2+c_x\left(s\right)}{d\left(s\right)\ddot{s}+e\left(s\right){\stackrel{.}{s}}^2+\mathrm{mg}}& \left[\mathrm{Equation}7\right]\end{array}$ $y_{\mathrm{ZMP}}=\frac{a_y\left(s\right)\ddot{s}+b_y\left(s\right){\stackrel{.}{s}}^2+c_y\left(s\right)}{d\left(s\right)\ddot{s}+e\left(s\right){\stackrel{.}{s}}^2+\mathrm{mg}}$ $\mathrm{where}{a}_x\left(s\right)=m_i{p}_{i_{1z}}{r}_x^p-m_i{p}_{i_{1x}}{r}_z^p-T_{i_{1y}}$ $b_x\left(s\right)=m_i{p}_{2_{1z}}{r}_x^p-m_i{p}_{i_{2x}}{r}_z^p-T_{i_{2y}}$ $c_x\left(s\right)=m_i{r}_x^{p}g$ $a_y\left(s\right)=m_i{p}_{i_{1z}}{r}_y^p-m_i{p}_{i_{1y}}{r}_z^p-T_{i_{1x}}$ $b_y\left(s\right)=m_i{p}_{i_{2z}}{r}_y^p-m_i{p}_{i_{2y}}{r}_z^p-T_{i_{2x}}$ $c_y\left(s\right)=m_i{r}_y^{p}g$ $d\left(s\right)=m_i{p}_{i_{1z}}$ $e\left(s\right)=m_i{p}_{i_{2z}}$ $\begin{array}{cc}\underset{\alpha ,\beta }{\min }{\int }_0^1\frac{1}{\sqrt{\beta \left(s\right)}}\mathrm{ds}& \left[\mathrm{Equation}8\right]\end{array}$ $\mathrm{subject}\mathrm{to}\beta \left(0\right)={\stackrel{.}{s}}_0^2$ $\beta \left(1\right)={\stackrel{.}{s}}_T^2$ ${\beta }^{\prime }\left(s\right)=2\alpha \left(s\right)$ $\beta \left(s\right)\ge 0$ $x_{\min }\le x_{\mathrm{ZMP}}\le x_{\max }$ $y_{\min }\le y_{\mathrm{ZMP}}\le y_{\max }$ $❘{\stackrel{.}{q}}_i❘\le c_i$

As described above, when the optimal rotation trajectory is obtained in consideration of the ZMP, the overturning of the excavator 300 may be effectively prevented, and a result thereof may be identified through simulation results. Specifically, reference numeral 410 in FIG. 4A denotes an optimization variable, reference numeral 420 denotes a path parameterization function over time, and reference numeral 430 denotes trajectories of joints of the front working device 230 over time. In addition, as shown by reference numerals 450 and 460 in FIG. 4B, when the excavator 300 follows the planned optimal rotation trajectory, it can be seen through simulation that the ZMP 443 is positioned within the supporting polygon 441 of the excavator 300.

According to various embodiments, the work control device 350 (or the work planning unit 352) may prevent collision with an obstacle while the excavator 300 performs a rotation operation. For example, the work control device 350 (or the work planning unit 352) may monitor the possibility of collision between the front work device 230 (e.g, the bucket 235, the arm 233, or the boom 231) and an obstacle while the rotation operation is being performed and regenerate an optimal rotation trajectory capable of avoiding collision in response to detection of the possibility of collision.

According to one embodiment, the work control device 350 (or the work planning unit 352) may calculate a minimum distance between the work device 230 and the obstacle based on information obtained through the sensor device 340 while the excavator 300 is performing a rotation operation, and monitor the possibility of collision based on the minimum distance. In this case, the work control device 350 (or the work planning unit 352) may perform modeling of the front work device 501 (e.g., the bucket 235) the the obstacle 503 in a polyhedron form as shown in FIG. 5A, in order to calculate the minimum distance between the front work device 230 and the obstacle.

According to one embodiment, the work control device 350 (or the work planning unit 352) may obtain a repulsion force (frep) and a contraction force (fcon) for at least a portion of the optimal rotation trajectory 505, for example, a portion of the optimal rotational trajectory where a collision with the obstacle 503 as shown in FIG. 5B in order to regenerate an optimal rotational trajectory capable of avoiding a collision. The repulsion force and the contraction force may be obtained by Equation 9 below based on the elastic band theory.

$\begin{array}{cc}{p}_i=[\begin{array}{ccc}{x}_i& y_i& {z_i]}^T\end{array}\leftarrow \mathrm{position}\mathrm{of}\mathrm{bucket}\mathrm{joint}& \left[\mathrm{Equation}9\right]\end{array}$ $f_{\mathrm{con}}=k_{\mathrm{con}}\left(\frac{p_{i-1}-p_i}{p_{i-1}-p_i}+\frac{p_{i+1}-p_i}{p_{i+1}-p_i}\right)$ $f_{\mathrm{rep}}=\{\begin{array}{cc}{k}_{\mathrm{rep}}\left(d_0-d_i\right)\frac{d_i}{d_i}& \mathrm{for}{d}_i<d_o\\ 0& \mathrm{for}{d}_i\ge d_o\end{array}$

In addition, the work control device 350 (or the work planning unit 352) may identify a collision avoidance point using the repulsion force and the contraction force, as shown in Equation 10 below, and regenerate (or update) the optimal rotation trajectory 507 capable of avoiding collision using the collision avoidance point as shown in FIG. 5C and Equation 11 below.

$\begin{array}{cc}{p}_i^{k+1}=p_i^k+\alpha f_i^k& \left[\mathrm{Equation}10\right]\end{array}$ $\mathrm{where}\{\begin{array}{c}{(·)}^k:k-\mathrm{th}\mathrm{iteration}\\ f_i=f_{i_{\mathrm{rep}}}+f_{i_{\mathrm{con}}}\end{array}$ $\begin{array}{cc}\mathrm{if}\left(p_{i+1}^k+\alpha f_{i+1}^k\right)-\left(p_i^k+\alpha f_i^k\right)\ge d_{\mathrm{threshold}},& \left[\mathrm{Equation}11\right]\end{array}$ $p_i^{k+1}=\left(p_i^k+\alpha f_i^k\right)$ $p_{i+2}^{k+1}=\left(p_{i+1}^k+\alpha f_{i+1}^k\right)$ $p_{i+1}^{k+1}=\frac{p_i^{k+1}+p_{i+2}^{k+1}}{2}$

As described above, it is possible to effectively detect collision between the excavator 300 and an obstacle through the operation of performing monitoring and the operation of regenerating an optimal rotation trajectory and results thereof may be identified as simulation results. Specifically, as shown in FIG. 5D, an optimal rotation trajectory capable of avoiding collision may be finally regenerated by repeatedly generating a new trajectory that is farther away from a collision point by a certain distance or more based on the first optimal rotation trajectory. As shown in FIG. 5E, it can be seen through simulation that the rotation trajectory 511 of the front work device 230, the movement trajectory 513 of the arm 233, the movement trajectory 515 of the boom 231, and the movement trajectory 517 of the bucket 235 avoid collision with the obstacle 503.

According to various embodiments, a dumping trajectory may be determined based on a dumping position and a dumping operation. The dumping position is the position of the tip of the bucket 235 for starting the dumping operation, and the dumping operation may include a waiting operation of placing the bucket 235 at the dumping position, a starting operation of rotating the bucket 235 to start dumping of soil, and a completion operation of completing the dumping of soil loaded on the bucket 235. In addition, when the dumping trajectory is obtained, the work control device 350 (or the driving control unit 354) may control the front work device 230 to perform a dumping operation according to the dumping trajectory.

According to various embodiments, the work control device 350 (or the work planning unit 352) may determine a dumping position based on information obtained through the sensor device 340.

According to one embodiment, the work control device 350 (or the work planning unit 352) may determines a dumping position such that the soil is evenly loaded in a loading container based on information on soil loaded in the loading container of the dump truck.

For example, as shown in FIG. 6A and Equation 12 below, a loading container 610 of the dump truck may be defined in the form of a polyhedron, the coordinates of the four vertices (c) constituting the upper surface of the loading container 610 may be identified, and the state of the soil loaded inside the loading container 610 may be obtained in the form of a point cloud.

$\begin{array}{cc}{𝒞}_{\mathrm{node}}=[\begin{array}{cccc}{c}_1& c_2& c_3& c_4]\mathrm{with}{c}_i\in {ℛ}^2\end{array}& \left[\mathrm{Equation}12\right]\end{array}$ $\begin{array}{c}𝒫=\bigcup _i{p}_i\\ =\bigcup _i\begin{array}{ccc}[p_{x_i}& p_{y_i}& p_{z_i}]\mathrm{with}[\begin{array}{cc}{p}_{x_i}& p_{y_i}]\in 𝒞\end{array}\end{array}\end{array}$

In addition, the work control device 350 (or the work planning unit 352) may divide the interior of the loading container 610 into grids of a certain size in order to determine the dumping position, and define a dumping area when the tip 622 of the bucket 235 of the excavator 620 is located in each grid and a point cloud corresponding to the dumping area as shown in Equation 13 below.

$\begin{array}{cc}\stackrel{\_}{𝒞}=\bigcup _k\left(x_k,y_k\right)& \left[\mathrm{Equation}13\right]\end{array}$ ${𝒟}_k:\mathrm{dumping}\mathrm{area}\mathrm{of}k-\mathrm{th}\mathrm{grid}\left(x_k,y_k\right)$ ${𝒟}_{k_{\mathrm{node}}}=\left[\begin{array}{ccc}\dots & R_{{\vartheta }_k}{d}_{k_i}+\left[\begin{array}{c}{x}_k\\ y_k\end{array}\right]& \dots \end{array}\right]$ $\mathrm{where}{\theta }_k={\tan }^{-1}\left(\frac{y_k}{x_k}\right)-\frac{\pi }{2}$ $R_{{\theta }_k}=\left[\begin{array}{cc}\cos {\theta }_k& -\sin {\theta }_k\\ \sin {\theta }_k& \cos {\theta }_k\end{array}\right]$ $[\begin{array}{cccc}{d}_{k_1}& d_{k_2}& d_{k_3}& d_{k_4}]\end{array}=\left[\begin{array}{cccc}w& w& -w& -w\\ 0& -h& -h& 0\end{array}\right]$ ${𝒫}_k=\bigcup _i\begin{array}{ccc}[p_{x_i}& p_{y_i}& p_{z_i}]\mathrm{with}[\begin{array}{cc}{p}_{x_i}& p_{y_i}]\in {𝒟}_k\end{array}\end{array}$ $:\mathrm{PCD}\mathrm{of}k-\mathrm{th}\mathrm{grid}\left(x_k,y_k\right)$

In addition, the work control device 350 (or the work planning unit 352) may determine a dumping position in such a way to set an average loading amount in a dumping area for each grid as a difference value (cost) and define a constraint such that the dumping area defined in each grid is located in the loading container 610.

$\begin{array}{cc}\underset{k}{\min }\frac{1}{N_k}\sum _{i=1}^{N_k}{p}_{z_i}& \left[\mathrm{Equation}14\right]\end{array}$ $\mathrm{subject}\mathrm{to}{𝒟}_{k_{\mathrm{node}}}\in 𝒞$ $\begin{array}{ccc}[p_{x_i}& p_{y_i}& p_{z_i}]\in {𝒫}_k\end{array}$ $\mathrm{where}{(·)}_k:k-\mathrm{th}\mathrm{grid}$ $N_k:\mathrm{number}\mathrm{elements}\mathrm{in}{𝒫}_k$

As described above, the dumping position may enable soil to be evenly loaded in the loading container, and the result thereof may be identified through simulation results. Specifically, as shown in FIG. 6B, the state 612 of soil inside the loading container 610 is represented inside the black line box, and it can be seen through simulation that the position of the tip 622 of the bucket 235 and the dumping area 630 obtained through the above algorithm are set such that the soil is not concentrated and loaded in one place in the loading container 610, and is loaded evenly.

According to one embodiment, the work control device 350 (or the work planning unit 352) may obtain a dumping operation based on the dumping position. For example, as shown in FIG. 6C, in the standby operation 641, it may be set that the lowermost end of the bucket 235 or 640 is spaced apart from the the loading container by a certain distance “d”, and the angle of the bucket 235 or 640 is horizontal with the ground surface, and the end of the tip 622 of the bucket 235 or 640 is positioned at the dumping position (x axis). Also, in the completion operation 645, it may be set that the end of the tip 622 of the bucket 235 or 640 and the joint of the bucket 235 or 640 are positioned at the dumping position, and the end of the tip 622 of the bucket 235 or 640 is spaced apart from the loading container 610 by a certain distance “d”. Based on this, while the standby operation 641, the start operation 643, and the completion operation 645 are sequentially performed, the position of the tip 622 of the bucket 235 or 640 correspond to the dumping position, so that soil may be evenly loaded in the loading container. As shown in FIG. 6D, it can be seen through results of simulation in which the the boom 231, the arm 233, and the bucket 235 are controlled such that the x-axis position of the tip 622 of the bucket 235 or 640 does not change and only the z-axis position and angle of the tip 622 of the bucket 235 change linearly while the dumping operation is performed.

In this case, the work control device 350 (or the work planning unit 352) may generate an optimal dumping trajectory which enables a dumping operation (or dumping trajectory) to be performed in a minimum time. A method of generating an optimal dumping trajectory may be the same as or similar to a method of generating an optimal rotation trajectory. For example, the optimal dumping trajectory may be obtained by the above-described <Equation 1> to <Equation 8>. In addition, it is possible to effectively prevent the excavator 300 from overturning in such a way that the optimal dumping trajectory uses the ZMP, and the result thereof may be identified through simulation results. Specifically, as shown in FIG. 6E, reference numeral 660 denotes an optimization variable, reference numeral 670 denotes a path parameterization function over time, and reference number 680 denotes trajectories of the joints of the front work device 230 over time, and it can be seen through simulation that rotation does not occur during dumping operation and the rotation angle is constant.

According to various embodiments, the work control device 350 (or the work planning unit 352) may obtain a return trajectory for returning the bucket 235 moved to the dumping position to a digging point as a portion of the work trajectory. The return trajectory may be obtained based on a position where the dumping operation has been performed and a position where the previous digging operation has been performed. In addition, when the return trajectory is obtained, the work control device 350 (or the driving control unit 354) may control the front work device 230 to perform a return operation according to the return trajectory or perform a digging operation with return operation.

In this case, the work control device 350 (or the work planning unit 352) may generate an optimal return trajectory for enabling the return operation to be performed in a minimum time. The optimal return trajectory may be the same as or similar to the method for generating the optimal rotation trajectory. For example, the optimal return trajectory may be obtained by the above-described <Equation 1> to <Equation 8>. Also, the work control device 350 (or the work planning unit 352) may monitor the possibility of collision between the front work device 230 (e.g, the bucket 235, the arm 233, or the boom 231) and an obstacle while the return operation is being performed and also regenerate an optimal return trajectory capable of avoiding collision in response to detection of the possibility of collision.

In the foregoing embodiment, the processor 310 and the work control device 350 have been described as being separated from each other, but this is only an example, and the present disclosure is not limited thereto. For example, the work control device 350 and the processor 310 may be designed as one component.

FIG. 7 is a flowchart illustrating an operating method of an autonomous work excavator 300 according to various embodiments of the present disclosure. In the following embodiments, operations may be performed sequentially, but not necessarily sequentially. In addition, the following operations may be performed by the processor 310 of the excavator 300 or implemented with instructions executable by the processor 310.

Referring to FIG. 7, an autonomous work excavator 300 (hereinafter referred to as an excavator 300) according to various embodiments may perform a digging operation in operation S710. The excavator 300 may perform a digging operation based on a work instruction received from an external device. According to one embodiment, the excavator 300 may generate a digging trajectory by recognizing surrounding environment and the state of the excavator 300 based on information obtained through at least one sensor device, and perform the digging operation according to the digging trajectory.

According to various embodiments, the excavator 300 may obtain a subsequent work trajectory in operation S720. The subsequent work trajectory may be a work trajectory for a subsequent operation that may be performed after the digging operation. For example, the subsequent work trajectory may include a rotation trajectory along which the tip of the bucket 235 or the arm 233 is to move to perform a rotation operation and a dumping trajectory along which the tip of the bucket 235 or arm 233 is to move to perform a dumping operation. Additionally, the subsequent work trajectory may include a return trajectory for moving the tip of the bucket 235 or the arm 233 to a digging point after the dumping operation.

According to various embodiments of the present disclosure, the excavator 300 may obtain (or generate) an optimal work trajectory using the subsequent work trajectory and the ZMP in operation S730. As described above, the ZMP refers to a point where a moment on the z axis exist but moments on the x and y axes are zero. For example, the optimal work trajectory may be obtained using <Equation 1> to <Equation 8> described above, and the optimal work trajectory may effectively prevent the excavator 300 from tipping over.

According to various embodiments of the present disclosure, the excavator 300 may perform a subsequent operation based on the obtained optimal work trajectory in operation S740. For example, the excavator 300 may perform control such that at least a portion of the front work device 230 (e.g., the boom 231, the arm 233 or the bucket 235, or the like) follows the optimal work trajectory.

FIG. 8 is a flowchart illustrating a method of processing a subsequent operation in an autonomous work excavator 300 according to various embodiments of the present disclosure. Operations of FIG. 8 described below may represent various embodiments for operations S720 to S740 of FIG. 7. In addition, in the following embodiments, the operations are not necessarily performed sequentially, and at least one operation among the operations disclosed may be omitted or another operation may be added.

Referring to FIG. 8, an autonomous work excavator 300 according to various embodiments (hereinafter, referred to as an excavator 300) may perform a digging operation and then perform a rotation operation and a dumping operation as subsequent operations.

According to various embodiments, the excavator 300 may obtain a rotation trajectory for dumping soil in operation S810. For example, the rotation trajectory may be a trajectory along which at least a portion of the front work device 230 (e.g., the tip of the bucket 235 or the arm 233) is to move in order to move the bucket 235 loaded with soil to the vicinity of the loading container.

According to various embodiments, the excavator 300 may obtain an optimal rotation trajectory using the rotation trajectory and the ZMP in operation S820. The optimal rotation trajectory may be a trajectory that allows the rotation operation to be performed in a minimum time, and the excavator 300 may limit a movement range of at least a portion of the front work device 230 by using the ZMP. This means that the movement of at least a portion of the front work device 230 is made within the ZMP range, thus effectively preventing the excavator 300 from overturning.

According to various embodiments, the excavator 300 may perform a rotation operation based on an optimal rotation trajectory in operation S830. For example, the excavator 300 may perform a boom-up operation of raising the position of the bucket 235 to a predetermined height or higher with respect to the digging point, and a rotation operation of moving the bucket 235 loaded with soil to the vicinity of the loading container.

According to various embodiments of the present disclosure, the excavator 300 may monitor the rotation operation based on the optimal rotation trajectory and sensor information in operation S840. The excavator 300 may detect a possibility of collision between at least a portion of the front work device 230 and an obstacle through monitoring while the rotation operation is performed. For example, the excavator 300 may calculate a minimum distance between the front work device 230 and the obstacle based on information obtained through the sensor device while the rotation operation is performed, and monitor the possibility of collision based on the minimum distance.

According to various embodiments, the excavator 300 may determine whether a collision with an obstacle is detected in operation S850.

According to various embodiments, when a collision with an obstacle is detected, the excavator 300 may regenerate an optimal rotation trajectory in operation S860. As will be described later with reference to FIG. 9, the optimal rotation trajectory may be regenerated as an optimal rotation trajectory capable of avoiding a collision based on the elastic band theory. However, this is merely an example, and embodiments of the present disclosure are not limited thereto. For example, various methods for avoiding collision with an obstacle may be used to regenerate an optimal rotation trajectory.

According to various embodiments of the present disclosure, when a collision with an obstacle is detected, the excavator 300 may determine whether the rotation operation is completed in operation S870. Completion of the rotation operation may include a state in which the bucket 235 is moved to the vicinity of the loading container.

According to various embodiments, when the rotation operation is completed, the excavator 300 may perform a dumping operation in operation S880.

FIG. 9 is a flowchart illustrating a method of regenerating a trajectory in an autonomous work excavator 300 according to various embodiments of the present disclosure. Operations of FIG. 9 described below may represent various embodiments of the operation S860 of FIG. 8. In addition, in the following embodiments, the operations are not necessarily performed sequentially, and at least one operation among the operations disclosed may be omitted or another operation may be added.

Referring to FIG. 9, the autonomous work excavator 300 (hereinafter, referred to as the excavator 300) according to various embodiments may obtain has a repulsion force (frep) and a contraction force (fcon) for a portion of the optimal rotation trajectory where a collision with an obstacle occurs in operation S910. The repulsion force and the contraction force may be obtained by <Equation 9> described above based on the elastic band theory.

The excavator 300 according to various embodiments may regenerate an optimal rotation trajectory based on the repulsion force and the contraction force in operation S920. According to an embodiment, the excavator 300 may identify a collision avoidance point using the repulsion force and the contraction force, and regenerate an optimal rotation trajectory capable of avoiding collision based on the collision avoidance point. The collision avoidance point may be identified based on the above-described Equation 10, and the optimal rotation trajectory may be regenerated based on the above-described Equation 11.

FIG. 10 is a flowchart illustrating a method of performing a dumping operation in an autonomous work excavator 300 according to various embodiments of the present disclosure. Operations of FIG. 10 described below may represent various embodiments of operations S720 to S740 of FIG. 7 or operation S880 of FIG. 8. In addition, in the following embodiments, the operations are not necessarily performed sequentially, and at least one operation among the operations disclosed may be omitted or another operation may be added.

Referring to FIG. 10, the autonomous work excavator 300 (hereinafter, referred to as the excavator 300) according to various embodiments may obtain a dumping position based on sensor information in operation $1010. The dumping position may be a position of the tip of the bucket 235 for starting the dumping operation. According to an embodiment, the dumping position may be determined such that soil is evenly loaded in a loading container based on the information obtained through a sensor device. At least a part of the sensor information obtained through the sensor device may be related to the shape of the loading container and the state of soil loaded inside the loading container. For example, the excavator 300 may use at least one of <Equation 12> to <Equation 14> described above in order to obtain the dumping position.

The excavator 300 according to various embodiments may obtain a dumping operation based on the dumping position in operation S1020. The dumping operation may include a waiting operation of placing the bucket 235 at the dumping position, a starting operation of rotating the bucket 235 to start dumping of soil, and a completion operation of completing the dumping of soil loaded on the bucket 235. According to an embodiment, the excavator may perform control such that the position of the tip of the bucket 235 corresponds to the dumping position while the standby operation, start operation, and completion operation are sequentially performed. This dumping operation may be used as a dumping trajectory.

The excavator 300 according to various embodiments may obtain an optimal dumping trajectory based on the dumping operation and the ZMP in operation S1030. The excavator 300 may limit a movement range of at least a portion of the front work device 230 using the ZMP. This means that the movement of at least a portion of the front work device 230 is made within the ZMP range, thus effectively preventing the excavator 300 from overturning.

According to various embodiments, the excavator 300 may perform a dumping operation based on an optimal dumping trajectory in operation S1040. For example, soil in the bucket 235 may be loaded into a loading container.

According to various embodiments, the excavator 300 may monitor a possibility of collision with an obstacle based on an optimal dumping trajectory and sensor information while the dumping operation is performed. Also, when a collision with an obstacle is detected, the excavator 300 may regenerate an optimal dumping trajectory to avoid the collision. A method of regenerating an optimal dumping trajectory may be similar to or the same as a method of reproducing an optimal rotation trajectory.

According to various embodiments, the excavator 300 may perform a return operation of returning the bucket 235 located at a dumping position to a previous digging point. In this case, the excavator 300 may determine a return trajectory based on a position where the dumping operation wad performed and a position where the previous digging operation was performed, and obtain an optimal return trajectory based on the return trajectory and the ZMP. Additionally, the excavator 300 may monitor a possibility of collision with an obstacle based on the optimal return trajectory and sensor information while the return operation is being performed. In this case, when a collision with an obstacle is detected, the excavator 300 may regenerate a return dumping trajectory to avoid the collision. A method of regenerating an optimal return trajectory may be similar to or the same as a method of reproducing an optimal rotation trajectory.

An operating method of the excavator 300 according to embodiments of the present disclosure may be implemented with instructions stored in a computer-readable storage medium and executable by a processor (e.g., the processor 310).

The storage medium can comprise a database, including distributed, such as a relational database, a non-relational database, an in-memory database, or other suitable databases, which can store data and allow access to such data via a storage controller, whether directly and/or indirectly, whether in a raw state, a formatted state, an organized stated, or any other accessible state. In addition, the storage medium can comprise any type of storage, such as a primary storage, a secondary storage, a tertiary storage, an off-line storage, a volatile storage, a non-volatile storage, a semiconductor storage, a magnetic storage, an optical storage, a flash storage, a hard disk drive storage, a floppy disk drive, a magnetic tape, or other suitable data storage medium.

Although the embodiments have been provided to illustrate the present disclosure in conjunction with the drawings, it will be apparent to those skilled in the art that the embodiments are given by way of illustration only, and that various modifications and equivalent embodiments can be made without departing from the spirit and scope of the invention. Therefore, the true technical protection scope of the present disclosure should be determined by the technical spirit of the attached claims.

Claims

1. An excavator comprising: a front work device including an arm, a boom, and a bucket;a sensor device configured to collect state information of the excavator and information related to surrounding environment; anda processor electrically connected to the front work device and the sensor device,wherein the processor is configured to:perform a digging operation such that soil is loaded in the bucket based on a work instruction;calculate a zero-moment point (ZMP) of a force acting on the excavator based on mass information on at least a portion of the front work device after the digging operation has been performed; andobtain a work trajectory for processing the soil loaded in the bucket by using the ZMP and the information related to surrounding environment.

2. The excavator of claim 1, wherein the processor is configured to: obtain a rotation trajectory for at least a portion of the front work device based on the state information of the excavator and the information related to surrounding environment;obtain the work trajectory using the rotation trajectory and the ZMP; andperform a rotation operation of moving the bucket from a digging point to a vicinity of a loading container according to the work trajectory.

3. The excavator of claim 2, wherein the processor is configured to obtain the work trajectory to follow the rotation trajectory in a minimum time.

4. The excavator of claim 1, wherein the processor is configured to: obtain a dumping position where a tip of the bucket is to be located based on the state information of the excavator and the information related to surrounding environment;obtain a dumping trajectory for at least a portion of the front work device such that the soil is loaded at the dumping position;obtain the dumping trajectory using the rotation trajectory and the ZMP; andperform a dumping operation of loading the soil stored in the bucket into a loading container according to the work trajectory.

5. The excavator of claim 4, wherein the processor is configured to obtain the work trajectory to follow the dumping trajectory in a minimum time.

6. The excavator of claim 4, wherein the processor is configured to control at least a portion of the front working device such that a position of the tip of the bucket is maintained at the dumping position while the dumping operation is performed.

7. The excavator of claim 4, wherein the processor is configured to obtain the dumping position based on a state of the soil loaded in the loading container.

8. The excavator of claim 1, wherein the processor is configured to: process the soil based on the work trajectory;monitor a collision between the at least a portion of the front work device and an obstacle based on the state information of the excavator and the information related to surrounding environment while the soil is being processed; andupdate the work trajectory when a collision between the at least a portion of the front work device and the obstacle is detected.

9. The excavator of claim 8, wherein the processor is configured to: obtain a repulsion force and a contraction force for a portion of the work trajectory where the collision with an obstacle occurs;obtain a collision avoidance point based on the repulsion force and the contraction force; andupdate the work trajectory based on the collision avoidance point.

10. The excavator of claim 1, wherein the processor is configured to: obtaining a return trajectory for the front work device based on the state information of the excavator and the information related to surrounding environment;recalculate a ZMP (Zero-moment Point) of the force acting on the excavator based on the mass information of the at least a portion of the front work device;obtain the work trajectory using the return trajectory and the recalculated ZMP; andperform a return operation of returning the bucket to a digging point according to the work trajectory.

11. The excavator of claim 1, wherein the mass information includes weight measurement information of the bucket.

12. An operation method of an excavator comprising: performing a digging operation based on a work instruction;calculating a zero-moment point (ZMP) of a force acting on the excavator based on mass information on at least a portion of a front work device including an arm, a boom, and a bucket after the digging operation has been performed;obtaining a work trajectory for processing soil loaded in the bucket using the ZMP; andperforming a rotation operation of moving the bucket from a digging point to a vicinity of a loading container according to the work trajectory.

13. The excavator of claim 12, wherein the obtaining of the work trajectory comprises: obtaining a rotation trajectory for at least a portion of the front work device based on the state information of the excavator and the information related to surrounding environment; andobtaining the work trajectory using the rotation trajectory and the ZMP.

14. The excavator of claim 12, wherein the obtaining of the work trajectory comprises:obtaining a dumping position where a tip of the bucket is to be located based on the state information of the excavator and the information related to surrounding environment;obtaining a dumping trajectory for at least a portion of the front work device such that the soil is loaded at the dumping position; andobtaining the work trajectory using the dumping trajectory and the ZMP; andwherein the method further comprises:performing a dumping operation of loading the soil stored in the bucket into a loading container according to the work trajectory.

15. The excavator of claim 12, further comprising: processing the soil based on the work trajectory;monitoring a collision between the at least a portion of the front work device and an obstacle based on the state information of the excavator and the information related to surrounding environment while the soil is being processed; andupdating the work trajectory when a collision between the at least a portion of the front work device and the obstacle is detected.

16. The excavator of claim 15, wherein the updating of the work trajectory comprises: obtaining a repulsion force and a contraction force for a portion of the work trajectory where the collision with an obstacle;obtaining a collision avoidance point based on the repulsion force and the contraction force; andupdating the work trajectory based on the collision avoidance point.

17. The excavator of claim 12, wherein the obtaining of the work trajectory comprises: obtaining a return trajectory for the front work device based on the state information of the excavator and the information related to surrounding environment; andobtaining the work trajectory using the return trajectory and the ZMP,wherein a return operation of returning the bucket to a digging point is performed according to the work trajectory.