EXCAVATORS AND EXCAVATOR CONTROL DEVICE

Abstract

[Problem] To provide a control device for an excavator capable of preventing a hidden object from being destroyed during excavation work. [Solution] A controller 30 serving as a control device for an excavator 100 includes a detection device configured to detect information about ground raised by excavation. The controller 30 estimates the presence or absence of a hidden object, such as a water pipe U1, based on at least one of an excavation reaction force calculated during excavation by an excavation attachment AT of the excavator 100 and information detected by the detection device. When the controller 30 estimates that the hidden object is present, the controller 30 can control movement of the excavation attachment AT to avoid contact between the hidden object and the excavation attachment AT.

Description

TECHNICAL FIELDThe present invention relates to an excavator and a control device for the excavator.PRIOR ARTConventionally, an excavator is known as an excavation machine for excavation of soil (see Patent Document 1). This excavator is configured to be capable of digging soil by moving a nose piece attached to the upper swing body.PRIOR ART DOCUMENTPATENT DOCUMENTPatent Document 1: WO 2015 / / 194601SUMMARY OF THE INVENTIONPROBLEMS TO BE SOLVED BY THE INVENTIONHowever, when excavation work is performed by an excavator at a construction site where a concealed / buried object such as a water pipe is buried in the ground, there is a possibility that the concealed object is accidentally destroyed.Accordingly, in view of the above-described case, it is desirable to provide a control device for an excavator capable of preventing a hidden object from being destroyed during excavation work.MEANS FOR SOLVING THE PROBLEMSAccording to an embodiment of the present invention, a control device for an excavator is provided. The control device includes:a detection device configured to detect information on a excavated soil,wherein the control device estimates presence or absence of a hidden object on the basis of at least one of an excavation reaction force calculated during excavation by an excavation attachment of the excavator or information detected by the detection device.EFFECT OF THE INVENTIONAccording to the above-described embodiment, there is provided a control device for an excavator capable of preventing a hidden object from being destroyed during excavation work.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a side view of an excavator according to an embodiment of the present invention. FIG. 2 is a side view of the excavator showing a relationship between an excavation extension of the excavator of FIG. 1 and various physical quantities. FIG. 3 is a diagram showing a configuration example of a basic system mounted on the excavator of FIG. 1. FIG. 4 is a diagram showing a configuration example of an excavation control system mounted on the excavator of FIG. 1. FIG. 5 is a cross-sectional view of a floor in which a water pipe is buried. FIG. 6 is a diagram showing a relationship between an excavation reaction force and an approach distance. FIG. 7 is a diagram showing an example of an image output on an image display unit. FIG. 8 is a diagram showing another configuration example of an excavation control system. FIG. 9 is a cross-sectional view of a floor in which a water pipe is buried. FIG. 10 is a plan view of an excavation attachment performing an excavation operation. FIG. 11 is a schematic diagram showing a configuration example of a control system of the excavator.EMBODIMENT OF THE INVENTIONFirst, an excavator (excavator 100) as an excavation machine according to an embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a side view of the excavator 100 according to an embodiment of the present invention. On a lower traveling body 1 of the excavator 100 illustrated in FIG. 1, an upper swing body 3 is pivotally mounted via a swing mechanism 2. A boom 4 is attached to the upper swing body 3, an arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to a tip of the arm 5. The boom 4, the arm 5, and the bucket 6 constitute, as working elements, an excavation attachment AT, which is an example of an attachment. The boom 4 is driven by a boom cylinder 7, the arm 5 is driven by an arm cylinder 8, and the bucket 6 is driven by a bucket cylinder 9. The upper swing body 3 is provided with a cab 10, and a power source such as a motor 11 is mounted in the upper swing body 3.On the excavation attachment AT, a posture detection device M 1 is attached. The posture detection deviceM 1 is an example of a detection device that is a device that detects information on an excavation reaction force. Specifically, the posture detection device M 1 is configured to be capable of detecting the posture of the attachment AT. In the illustrated example, the posture detection device M 1 includes a boom angle sensor M 1 a, an arm angle sensor M 1 b, and a bucket angle sensor M 1 c.The boom angle sensor M 1 ais a sensor that detects a boom angle, and includes, for example, a rotation angle sensor that detects a rotation angle of a boom foot pin, a stroke sensor that detects a stroke amount of the boom cylinder 7, and an inclination sensor (acceleration sensor) that detects an inclination angle of the boom 4. The same applies to the arm angle sensor M 1 band the blade angle sensor M 1 c.The upper swing body 3 is equipped with a cab 10 as an operator seat, and a power source such as a motor 11 is mounted in the upper swing body 3. The drive source may be an electric motor. On the upper swing body 3, an object detection device 70 and the like are mounted. In an operation device 26, a controller 30, a display device 40, a sound output device 45, and the like are provided inside the cabin. In this description, for convenience, a side of the upper swing body 3 on which the boom 4 is mounted is referred to as a front side and a side on which the counterweight is mounted is referred to as a rear side.The object detection device 70 is configured to detect an object located around the excavator 100. The object is, for example, a person, an animal, a vehicle, another construction machine, a building, a hole or the like. The object detection device 70 is, for example, an ultrasonic sensor, a millimeter wave radar, an imaging device, an infrared sensor, or the like. The imaging device is, for example, a monocular camera, a stereo camera, a LIDAR (Light Detection And Ranging), or a range image sensor. In the illustrated example, the object detection device 70 includes a rear camera 70B attached to the rear end of the upper surface of the upper swing body 3, a front camera 70F attached to the front end of the upper surface of the cabin 10, a left camera 70L attached to the left end of the upper surface of the upper swing body 3, and a right camera 70R attached to the right end of the upper surface of the upper swing body 3.The object detection device 70 may be configured to be capable of detecting a predetermined object (for example, a person) in an area set around the excavator 100. For example, the object detection device 70 may be configured to be able to detect a person and an object other than a person in a distinguishable manner.FIG. 2 is a side view of the excavator 100 showing various physical quantities with respect to the excavation attachment AT. The boom angle sensor M 1 adetects a boom angle θ 1, for example. The boom angle θ 1 is an angle of a line segment P 1-P 2 connecting the boom butt pin position P 1 and a P arm coupling pin position P 2 with respect to the horizontal line in an XZ plane. The arm angle sensor M 1 bdetects an arm angle θ 2, for example. The arm angle θ 2 is an angle of a line segment P 2-P 3 connecting the arm coupling bolt position P 2 and a blade coupling bolt position P 3 with respect to the horizontal line in the XZ plane. The blade angle sensor M 1 cdetects a blade angle θ 3, for example. The blade angle θ 3 is an angle of a line segment P 3-P 4 connecting a blade coupling pin position P 3 and a blade claw tip position P 4 with respect to the horizontal line in the XZ plane. The blade angle θ 3 may be calculated based on the operation content of the operation device 26. For example, the blade angle θ 3 may be calculated based on the outputs of pilot pressure sensors 15 aand 15 band the like. In this case, the blade angle sensor M 1 cmay be omitted.Next, a basic system of the excavator 100 will be described with reference to FIG. 3. The basic system of the excavator 100 basically includes the engine 11, a main pump 14, a pilot pump 15, the control valve unit 17, the operation device 26, the controller 30, the display device 40, the sound output device 45, an engine control device 74, an operation mode switching switch 75, a hidden object detection mode switch 76, a posture detection device M 1, an excavation pressure sensor S 1, and the like.The engine 11 is a drive source of the excavator 100, and is, for example, a diesel engine that operates to maintain a predetermined rotational speed. An output shaft of the motor 11 is connected to the respective input shafts of the main pump 14 and the pilot pump 15.The main pump 14 is a hydraulic pump that supplies hydraulic fluid to the control valve 17 via a hydraulic fluid line 16, and is, for example, a swash plate type variable displacement hydraulic pump. In a swash plate type variable displacement hydraulic pump, the stroke length of a piston that determines the displacement volume changes in response to a change in the swash plate inclination angle, thereby changing the discharge flow rate per revolution. The swash plate inclination angle is controlled by a regulator 14a. The regulator 14 achanges the swash plate inclination angle in response to a change in the control current from the controller 30, for example, the regulator 14 aincreases the N swash plate inclination angle in response to an increase in the control current to increase the discharge flow rate of the main pump 14. Alternatively, the regulator 14 adepresses the swash plate inclination angle in response to a decrease in the control current to reduce the discharge flow rate of the main pump 14. A discharge pressure sensor 14 bdetects the discharge pressure of the main pump 14, and an oil temperature sensor 14 cdetects the temperature of the hydraulic fluid sucked by the main pump 14.The pilot pump 15 is a hydraulic pump for supplying the hydraulic fluid to various hydraulic control devices such as the operating device 26 via a pilot line 25, and is, for example, a fixed displacement hydraulic pump.The control valve unit 17 is configured to control the flow of hydraulic fluid with respect to the hydraulic actuator. In the illustrated example, the control valve unit 17 includes a plurality of flow rate control valves. The control valve unit 17 selectively supplies the hydraulic fluid obtained from the main pump 14 through the hydraulic fluid line 16 to one or more hydraulic actuators according to a pressure change (pilot pressure) corresponding to the operation direction and operation amount of the operating device 26. The hydraulic actuators include, for example, the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, a left travel hydraulic motor 1A, a right travel hydraulic motor 1B, and the swing hydraulic motor 2A. In the illustrated example, the hydraulic motors (the left travel hydraulic motor 1A, the right travel hydraulic motor 1B, and the swing hydraulic motor 2A) are swash plate type reciprocating motors. However, at least one of the hydraulic motors may be an electric motor.The operation device 26 is a device that the operator uses to operate the hydraulic actuators, and includes a lever 26A, a lever 26B, a pedal 26C, and the like. The operating device 26 receives the hydraulic fluid supplied from the pilot pump 15 via the pilot line 25 and generates a pilot pressure. The operating device 26 applies the pilot pressure to the pilot port of the corresponding flow rate control valve via the pilot line 25 a. The pilot pressure changes according to the operation direction and the operation amount of the operation device 26. In this case, the operation device 26 generates the pilot pressure according to the information on the operation direction and the operation amount received via wireless communication.The operating device 26 may also be an electric operating device instead of the above-described hydraulic operating device. In this case, an electromagnetic valve for adjusting the pilot pressure may be disposed between the flow rate control valve in the control valve unit 17 and the pilot pump 15. Information on the operation direction and the operation amount of the electric operation device is transmitted from the electric operation device to the controller 30 as an electric signal. The controller 30 may adjust the amount of pilot pressure acting on the control valve by adjusting the opening area of the electromagnetic valve according to the electric signal received from the electric operating device.The controller 30 is a control device for controlling the excavator 100. In the illustrated example, the controller 30 is configured by a computer including a circuit or a CPU, a volatile memory device, a nonvolatile memory device, and the like. The CPU of the controller 30 reads programs corresponding to various functions from the nonvolatile memory device, loads the programs into the volatile memory device, and executes the programs, thereby implementing the functions corresponding to the programs.The controller 30 implements, for example, a function of controlling the discharge flow rate of the main pump 14. In detail, the controller 30 changes the amount of control current to the regulator 14 aaccording to the hydraulic pressure in the negative control valve, and controls the discharge flow rate of the main pump 14 via the regulator 14 a.The display device 40 is a device that displays various kinds of information and is disposed near an operator seat in the cabin 10. In the illustrated example, the display device 40 includes an image display unit 41 and an input unit 42. The input unit 42 is a membrane switch. An operator can input information and commands to the controller 30 using the input unit 42. Further, the operator can grasp the operation state and the control information of the excavator 100 by viewing the image display unit 41. The display device 40 is connected to the controller 30 via a communication network such as a controller area network (CAN). However, the display device 40 may be connected to the controller 30 via a leased line.The display device 40 operates by receiving power supplied from a storage battery 90. In the example shown, the storage battery 90 is charged with power generated by an alternator 11a. The electric power of the storage battery 90 is also supplied to devices other than the controller 30 and the display device 40, such as an electric component 72 of the excavator 100. A starter 11 bof the engine 11 may be operated by power from the storage battery 90 to start the engine 11.The sound output device 45 is a device that outputs sound information. In the illustrated example, the sound output device 45 is a speaker disposed near the operator seat in the cabin 10. The sound output device 45 may be a buzzer.The motor control device 74 is a device that controls the motor 11. The engine control device 74 controls, for example, the fuel injection amount and the like so that the engine speed set via the input device is implemented.The motor 11 is controlled by the motor control device 74. The engine control device 74 transmits various kinds of information indicating the state of the engine 11 (for example, information on physical quantities such as information on coolant temperature detected by a coolant temperature sensor 11 c) to the controller 30. the controller 30 stores the information in a temporary storage unit (memory) 30 aand may transmit the information to the display device 40 or the like as appropriate. The same applies to data indicating the swash plate inclination angle output from the regulator 14 a, data indicating the output pressure of the main pump 14 output from the output pressure sensor 14 b, data indicating the temperature of the hydraulic fluid output from the oil temperature sensor 14 c, and data indicating the pilot pressure output from the pilot pressure sensors 15 aand 15 b.The operation mode switching switch 75 is a switch for switching an operation mode of the excavator 100, and is provided in the cab 10. In the illustrated example, by operating the mode switch 75, the operator can switch between a manual (M) mode and a semi-automatic (SA) mode. The controller 30 is configured to switch the operation mode of the excavator 100, for example, according to the output of the operation mode switching switch 75. FIG. 3 shows a state in which the SA mode is selected by the operation mode switching switch 75.The M mode is a mode in which the excavator 100 is operated according to the content of an operation input to the operation device 26 by the operator. For example, the operation mode is a mode in which the boom cylinder 7, the arm cylinder 8, the bucket cylinder 9, and the like are operated by the operator according to the content of the operation input to the operation device 26. The SA mode is a mode in which the excavator 100 is automatically operated when a predetermined condition is satisfied, regardless of the content of the operation input to the operation device 26. For example, the SA mode is a mode in which at least one of the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 is automatically operated regardless of the content of the operation input to the operation device 26 when a predetermined condition is satisfied. The operation mode switching switch 75 may be configured to be capable of switching three or more operation modes.The hidden object detection mode switch 76 is a switch for activating the hidden object detection function, and is provided in the cabin 10. The hidden object detection function is a function of detecting a hidden / buried object in the ground to be excavated. In the illustrated example, the hidden / buried object detection function is configured to detect the presence or absence of a hidden / buried object based on the excavation reaction force. In the example shown, by actuating the hidden object detection mode switch 76, the operator may toggle between activation and deactivation of the hidden object detection function. The controller 30 is configured to switch between activation and deactivation of the hidden object detection function, for example, according to an output of the hidden object detection mode switch 76. Specifically, the controller 30 is configured to activate the hidden object detection function in response to an activation command of the hidden object detection mode switch 76, and deactivate the hidden object detection function in response to a deactivation command of the hidden object detection mode switch 76. However, the controller 30 may activate the hidden object detection function when it is determined that the excavation operation is performed based on the posture of the excavation attachment AT or the like independently of the operation of the hidden object detection mode switch 76. In this case, the controller 30 may continuously execute the hidden object detection function from, for example, the time point at which the excavation operation is started to the time point at which the boom raising operation is performed.The excavation pressure sensor S 1 is an example of a detection device that detects information on an excavation reaction force and detects a pressure of a hydraulic fluid in the hydraulic cylinder such as the boom cylinder 7, and outputs the detected pressure to the controller 30. In the illustrated example, the excavation pressure sensor S 1 includes excavation pressure sensors S 11 to S 18. Specifically, the excavation pressure sensor S 11 detects a boom bottom pressure, which is a hydraulic pressure of hydraulic fluid in a bottom-side hydraulic chamber of the boom cylinder 7. The excavation pressure sensor S 12 detects a boom rod pressure, which is a hydraulic pressure of hydraulic fluid in a rod side hydraulic chamber of the boom cylinder 7. Similarly, the excavation pressure sensor S 13 detects an arm bottom pressure, the excavation pressure sensor S 14 detects an arm rod pressure, the excavation pressure sensor S 15 detects a blade bottom pressure, and the excavation pressure sensor S 16 detects a blade rod pressure. The excavation pressure sensor S 17 detects a left swivel pressure that is a hydraulic pressure of the hydraulic fluid at a first port (left port) of the swivel hydraulic motor 2A, and the excavation pressure sensor S 18 detects a right swivel pressure that is a hydraulic pressure of the hydraulic fluid at a second port (right port) of the swivel hydraulic motor 2A.A control valve E1 is operated in response to a command from the controller 30. In the illustrated example, the control valve E 1 is used to forcibly operate the flow rate control valves associated with predetermined hydraulic cylinders regardless of the operation input of the operation content to the operation device 26. When the above-described electric operating device is applied, the control valve E 1 corresponds to an electromagnetic valve disposed between the flow rate control valves and the pilot pump 15.FIG. 4 is a diagram showing a configuration example of an excavation control system mounted on the excavator 100 of FIG. 1. The excavation control system is mainly configured by the posture detection device M 1, the excavation pressure sensor S 1, the operation mode switching switch 75, the hidden object detection mode switch 76, the controller 30, the control valve E 1, the display device 40, and the sound output device 45.The excavation reaction force calculation unit 31 is a functional element that calculates an excavation reaction force. The excavation reaction force calculation unit 31 is configured to calculate an excavation reaction force based on at least the output of the excavation pressure sensor S 1. In the illustrated example, the excavation reaction force calculation unit 31 calculates the excavation reaction force based on outputs of the excavation pressure sensor S 1 and the posture of the excavation attachment AT detected by the posture detection device M 1. The excavation reaction force calculation unit 31 may additionally use an output of a body inclination sensor. The body inclination sensor may be configured by, for example, an acceleration sensor or a gyro sensor.The output of the excavation pressure sensor S 1 includes, for example, at least one of a boom bottom pressure (P 11), a boom rod pressure (P 12), an arm bottom pressure (P 13), an arm rod pressure (P 14), a bucket bottom pressure (P 15), and a bucket rod pressure (P 16) detected by the excavation pressure sensors S 11 to S 16.The excavation reaction force calculation unit 31 may calculate a cylinder thrust based on the output of the excavation pressure sensor S 1. The cylinder thrust is calculated based on, for example, an exhaust pressure and a pressure receiving area of the piston sliding in the cylinder. The cylinder thrust includes, for example, a boom cylinder thrust (f 1), an arm cylinder thrust (f 2), and a bucket cylinder thrust (f 3). Specifically, as illustrated in FIG. 2, the boom cylinder thrust (f 1) is represented by the difference (P 11×A 11- P 12×A 12) between a cylinder extension force, which is a product (P 11×A 11) of the boom bottom pressure (P 11) and a pressure receiving area (A 11) of the piston in a boom bottom side oil chamber, and a cylinder retraction force, which is a product (P 12×A 12) of the boom rod pressure (P 12) and a pressure receiving area (A 12) of the piston in a boom rod oil chamber. The same applies to the arm cylinder thrust (f 2) and the bucket cylinder thrust (f 3).The excavation reaction force calculation unit 31 may calculate an excavation torque based on the posture of the excavation attachment AT and the cylinder thrust. As illustrated in FIG. 2, the amount of bucket lift torque (τ3) is represented by a value obtained by multiplying the amount of bucket cylinder thrust (f3) by a distance G3 between the line of action of the bucket cylinder thrust (f3) and the bucket clutch pin position P3. The distance G 3 is a function of the blade angle θ 3 and is an example of a joint gain. The same applies to the boom excavation torque (τ 1) and an arm excavation torque (τ 2). The distance G 1 is a distance between the line of action of the boom cylinder thrust (f 1) and the boom butt pin position P 1, and the distance G 2 is a distance between the line of action of the arm cylinder thrust (f 2) and the arm link pin position P 2.The excavation reaction force is calculated as, for example, a product of a mechanism function having the boom angle θ 1, the arm angle θ 2, and the bucket angle θ 3 as arguments and a function having a boom excavation torque (τ 1), the arm excavation torque (τ 2), and the bucket excavation torque (τ 3) as arguments, as illustrated in FIG. 2. The function having the boom excavation torque (τ1), the arm excavation torque (τ2), and the bucket excavation torque (τ3) as arguments may be a function having the boom cylinder thrust (f1), the arm cylinder thrust (f2), and the bucket cylinder thrust (f3) as arguments.The function having the boom angle θ 1, the arm angle θ 2, and the blade angle θ 3 as arguments may be based on a force balance equation, a Jacobian formula, or the principle of virtual work.In this way, the value of the excavation reaction force is derived based on the current detection values of the various sensors. However, the detection value of the excavation pressure sensor S 1 may be used as a value of the excavation reaction force as it is. Alternatively, a value of the cylinder thrust calculated based on the detection value of the excavation pressure sensor S 1 may be used as the value of the excavation reaction force. Alternatively, as the value of the excavation reaction force, a value of the excavation torque calculated from the value of the cylinder thrust calculated based on the detection value of the excavation pressure sensor S 1 and a value related to the position of the excavation extension AT derived based on the detection value of the posture detection device M 1 may be used.The excavation reaction force calculation unit 31 may calculate an excavation reaction force acting in the swing direction based on the outputs of the excavation pressure sensor S 17 and the excavation pressure sensor S 18. In the illustrated example, the upper swing body 3 attempts to swing in the left direction when a left swing pressure (P 17) detected by the excavation pressure sensor S 17 is greater than a right swing pressure (P 18) detected by the excavation pressure sensor S 18. Further, the upper swing body 3 attempts to swing in the right direction when the right swing pressure (P 18) detected by the excavation pressure sensor S 18 is greater than the left swing pressure (P 17) detected by the excavation pressure sensor S 17. For example, the excavation reaction force calculation unit 31 may calculate the left swivel pressure (P 17) as the excavation reaction force acting in the left swivel direction in a case where the left swivel pressure (P 17) is larger than the right swivel pressure (P 18). Further, for example, the excavation reaction force calculation unit 31 may calculate the right swivel pressure (P 18) as the excavation reaction force acting in the right swivel direction in a case where the right swivel pressure (P 18) is larger than the left swivel pressure (P 17). Note that, when an electric swing motor is mounted instead of the swing hydraulic motor 2A, the excavation reaction force calculation unit 31 may calculate the excavation reaction force acting in the swing direction on the basis of electric power information such as an orientation and amount of an electric current supplied to the electric swing motor.The hidden object detection unit 32 is configured to be capable of detecting a hidden object on the basis of information on the excavation reaction force. In the illustrated example, the hidden object detection unit 32 is configured to be capable of estimating (determining) the presence or absence of a hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31.Then, for example, when the hidden object detection unit 32 estimates that the hidden object exists, the hidden object detection unit 32 outputs a control command to the control valve E 1.The control valve E 1 is configured to forcibly operate the flow rate control valves associated with the predetermined hydraulic cylinders to forcibly extend and retract the predetermined hydraulic cylinders regardless of the content of the operation input to the operation device 26 when receiving the control command from the hidden object detection unit 32. In the illustrated example, the control valve E 1 is configured to be capable of forcibly extending the boom cylinder 7 by forcibly moving the flow rate control valve associated with the boom cylinder 7 even when, for example, the boom operation lever is not operated. As a result, the control valve E1 can keep the excavation depth small by forcibly raising the boom 4. Alternatively, even when the arm operation lever is operated, the control valve E 1 may forcibly deactivate the arm cylinder 8 by forcibly moving the flow rate control valve associated with the arm cylinder 8. In this case, the control valve E 1 can prevent contact between the blade 6 and the concealed object by forcibly deactivating the arm 5. In this way, the control valve E 1 can prevent the contact between the excavation extension AT and the hidden object by forcibly extending or contracting the boom cylinder 7, the arm cylinder 8, or the bucket cylinder 9 in response to the control command of the hidden object detection unit 32.The hidden object detection unit 32 may output a control command to the display device 40 when it estimates that a hidden object is present. The display device 40 may be configured to display an estimated position of the hidden object when receiving a control command from the hidden object detection unit 32. For example, the display device 40 may display a virtual viewpoint image representing a state when the excavator 100 is viewed from a virtual viewpoint directly above the excavator 100, and may superimpose and display a figure relating to an actually invisible object hidden in the ground on the virtual viewpoint image. In the illustrated example, the virtual viewpoint image is generated based on images captured by the rear camera 70B, the left camera 70L, and the right camera 70R. Note that an image captured by the front camera 70F may be additionally used when the virtual viewpoint image is synthesized. Alternatively, the display device 40 may display an image representing a cross section of the ground where the excavator 100 is located, and may superimpose and display a figure relating to an actually invisible object hidden in the ground on the virtual viewpoint image.The hidden object detection unit 32 may output a control command to the sound output device 45 when it is estimated that the hidden object is present. The sound output device 45 may output a voice message to notify the operator of the presence of the hidden object when receiving the control command from the hidden object detection unit 32. Alternatively, the sound output device 45 may output an alarm sound to notify the operator of the presence of the hidden object.The controller 30 may be configured to activate the hidden object detection function in response to an activation command of the hidden object detection mode switch 76. In the illustrated example, when the hidden object detection function is activated, the hidden object detection unit 32 may estimate the presence or absence of the hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31. On the other hand, the controller 30 may be configured to deactivate the hidden object detection function in response to a deactivation command of the hidden object detection mode switch 76. In the illustrated example, when the hidden object detection function is disabled, the hidden object detection unit 32 does not estimate whether or not a hidden object exists. This is intended to prevent the control command from being outputted to the control valve E 1, the display device 40, or the sound output device 45 because the presence of a concealed object is misjudged due to variations in the excavation reaction force even if it is clear that no concealed object is present.When the hidden object detection function is deactivated, the excavation reaction force calculation unit 31 may be configured not to calculate the excavation reaction force. Thereby, the calculation load is reduced.In the illustrated example, the hidden object detection function is configured to be executed even when the operation mode of the excavator 100 is any one of the M (manual) mode or the SA (semi-automatic) mode. However, the hidden object detection function may be configured to be executed only when the SA (semi-automatic) mode is selected. This is because the operator can move the excavation extension AT along a trajectory set in advance when the SA (semi-automatic) mode is selected, and as a result, the detection accuracy of the hidden object can be improved. When the SA (semi-automatic) mode is selected, an excavation operation for finding a hidden object (a series of operations from the insertion of the claw tip of the bucket 6 into the ground to the separation of the bucket 6 from the ground) can be automatically performed, for example, when the hidden object detection mode switch 76 is operated. That is, each excavation operation can be automatically executed each time the hidden object detection mode switch 76 is operated.The target trajectory is, for example, a trajectory to be followed by a predetermined portion of the excavation appendix AT. The predetermined excavation appendix AT is, for example, the claw tip of the bucket 6.Next, the movement of the excavator 100 when the operator of the excavator 100 finds a water pipe U 1 as a hidden object will be described with reference to FIG. 5. FIG. 5 shows a cross section of the floor in which a water line U 1 is concealed. The excavator 100 is located on the ground.In the example illustrated in FIG. 5, the operator of the excavator 100 first operates the operation mode switching switch 75 to switch the operation mode of the excavator 100 to the SA (semi-automatic) mode. Then, the operator manually operates the operating device 26 to bring the claw tip of the bucket 6 to a desired position. The desired position is, for example, a position directly above a point to which the claw tip of the blade 6 is to be inserted. After the operator brings the claw tip of the bucket 6 to the desired position, he operates the hidden object detection mode switch 76 to activate the hidden object detection function.In the example shown, the controller 30 autonomously operates the excavation appendix AT when the hidden object detection function is activated in the SA (semi-automatic) mode. Specifically, the controller 30 automatically extends and retracts the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 to move the predetermined portion of the excavation attachment AT along a trajectory TP set in advance. However, the controller 30 may be configured not to autonomously operate the excavation extension AT even when the hidden object detection function is activated, as in the case of the M (manual) mode. In this case, the excavation attachment AT operates according to the operation content of the operation device 26 by the operator.In the example illustrated in FIG. 5, the operator activates the hidden object detection function after moving the claw tip of the bucket 6 to a first position PS 1. The first position PS 1 is a position on a ground ES before excavation is performed. FIG. 5 shows the ground ES before excavation is performed in dashed lines. When the hidden object detection function is activated, the controller 30 automatically controls the excavation appendix AT so that the claw tip of the bucket 6 moves along a preset first target trajectory TP 1 (a dot-and-dash line).Then, the excavation reaction force calculation unit 31 repeatedly calculates the excavation reaction force based on the output of the posture detection device M 1 and the output of the excavation pressure sensor S 1 in a predetermined control cycle when the claw tip of the blade 6 moves along the first target trajectory TP 1.The hidden object detection unit 32 repeatedly estimates the presence or absence of a hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31 in the predetermined control cycle when the claw tip of the blade 6 moves along the first target trajectory TP 1.When the claw tip of the bucket 6 reaches the end of the first target trajectory TP 1, the controller 30 stops the autonomous operation of the excavation attachment AT. That is, the hidden object detection unit 32 does not detect the hidden object until the claw tip of the blade 6 has reached the end of the first target trajectory TP 1.Thereafter, the operator operates the hidden object detection mode switch 76 to disable the hidden object detection function. The controller 30 may disable the hidden object detection function when the operator manually operates the operation device 26 to perform the boom raising operation or the boom lowering and swinging operation. Thereafter, the operator performs the earth discharging operation and the boom lowering and swinging operation, and then moves the claw tip of the bucket 6 to a next desired position to perform a next excavation operation. In the example shown in FIG. 5, the operator deflates the soil in the bucket 6 by manual operation, and then moves the claw tip of the bucket 6 to a second position PS 2. At least one of the emptying of the soil in the bucket 6 and the movement of the bucket 6 to the second position PS 2 may be performed automatically. The second position PS 2 is a position on a first exposed surface exposed by the previous excavation operation. Specifically, the second position PS 2 on the first exposed surface is a position at a depth D 1 from the ground ES before the excavation is started, and is a position substantially directly below the first position PS 1. The operator moves the claw tip of the bucket 6 to the second position PS 2 and then activates the hidden object detection function. When the hidden object detection function is activated, the controller 30 automatically operates the excavation appendix AT so that the claw tip of the bucket 6 moves along a preset second trajectory TP 2 (a dash-dot line).Then, the excavation reaction force calculation unit 31 repeatedly calculates the excavation reaction force based on the output of the posture detection device M 1 and the output of the excavation pressure sensor S 1 in the predetermined control cycle when the claw tip of the bucket 6 moves along the second trajectory TP 2.The hidden object detection unit 32 repeatedly estimates the presence or absence of the hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31 in the predetermined control cycle when the claw tip of the bucket 6 moves along the second trajectory TP 2.When the claw tip of the bucket 6 reaches the end of the second trajectory TP 2, the controller 30 stops the autonomous operation of the excavation attachment AT. That is, the hidden object detection unit 32 does not detect the hidden object until the claw tip of the blade 6 has reached the end of the second target trajectory TP 2.Thereafter, the operator operates the hidden object detection mode switch 76 to disable the hidden object detection function. The controller 30 may disable the hidden object detection function when the operator manually operates the operation device 26 to perform the boom raising operation or the boom raising and swinging operation. Thereafter, the operator performs the earth discharging operation and the boom lowering and swinging operation, and then moves the claw tip of the bucket 6 to a next desired position to perform a next excavation operation. In the example illustrated in FIG. 5, the operator moves the claw tip of the bucket 6 to a third position PS 3. The third position PS 3 is a position on the second exposed surface exposed by the previous excavation operation. Specifically, the third position PS 3 is located on the second exposed surface at a depth D 2 from the first exposed surface and is substantially directly below the second position PS 2. In the example illustrated in FIG. 5, the depth D 2 is the same depth as the depth D 1. The operator activates the hidden object detection function after moving the claw tip of the bucket 6 to the third position PS 3. When the hidden object detection function is activated, the controller 30 automatically controls the excavation appendix AT so that the claw tip of the bucket 6 moves along a preset third target trajectory TP 3 (dot-and-dash line).Then, the excavation reaction force calculation unit 31 repeatedly calculates the excavation reaction force based on the output of the posture detection device M 1 and the output of the excavation pressure sensor S 1 in the predetermined control cycle when the claw tip of the blade 6 moves along the third target trajectory TP 3.The hidden object detection unit 32 repeatedly estimates the presence or absence of a hidden object on the basis of the excavation reaction forces calculated by the excavation reaction force calculation unit 31 in the predetermined control cycle when the claw tip of the blade 6 moves along the third target trajectory TP 3.In the example illustrated in FIG. 5, the hidden object detection unit 32 estimates that the hidden object is present when the claw tip of the bucket 6 reaches a fourth position PS 4. The fourth position PS 4 is a position at a depth D 3 from the second exposed surface, and is a position on the third trajectory TP 3. In the example illustrated in FIG. 5, the depth D 3 is the same depth as the depth D 1 and the depth D 2. The fourth position PS 4 is a position at which the distance between the water pipe U 1 and the claw tip of the blade 6 in the direction along the third target trajectory TP 3 becomes an AD 1. In the example illustrated in FIG. 5, the direction along the third target trajectory TP 3 is a horizontal direction.The details of the method for estimating the presence or absence of the hidden object by the hidden object detection unit 32 based on the excavation reaction force calculation unit 31 will be described herein with reference to FIG. 6. FIG. 6 is a diagram illustrating a relationship between an excavation reaction force F and an approach distance AD. A vertical axis of FIG. 6 corresponds to the excavation reaction force F calculated by the excavation reaction force calculation unit 31, and a horizontal axis of FIG. 6 corresponds to the approach distance AD. In the example illustrated in FIG. 5, the approach distance AD is a distance between the current position of the claw tip of the blade 6 and the water pipe U 1 in the direction along the target trajectory TP. FIG. 6 shows that the approach distance AD decreases from left to right on the horizontal axis until the approach distance AD reaches a value of zero. That is, the claw tip of the blade 6 is farther from the water passage U 1 at an approach distance AD of AD 0 than at an approach distance AD of AD 1.Specifically, a first transition TL 1 indicated by a dot-and-dash line in FIG. 6 indicates a relationship between the excavation reaction force and the approach distance AD that is repeatedly calculated at a predetermined control cycle when the excavation appendix AT operates autonomously or semi-autonomously to cause the tip of the bucket 6 to move along the first target trajectory TP 1 (see FIG. 5 ). Moreover, a second transition TL 2 indicated by a dotted line in FIG. 6 indicates a relationship between the excavation reaction force and the approach distance AD that is repeatedly calculated in a predetermined control cycle when the excavation appendix AT operates autonomously or semi-autonomously to cause the tip of the blade 6 to move along the second target trajectory TP 2 (see FIG. 5 ). A third transition TL 3, which is illustrated by a solid line in FIG. 6, indicates a relationship between the excavation reaction force and the approach distance AD, which is repeatedly calculated in a predetermined control cycle when the excavation appendix AT operates autonomously or semi-autonomously to cause the tip of the blade 6 to move along the third target trajectory TP 3 (see FIG. 5 ).All of the first to third transitions TL 1 to TL 3 represent states in which the excavation reaction force F increases substantially constantly as the approach distance AD decreases. This is because the amount of soil taken into the bucket 6 increases as the bucket 6 approaches the body (upper swing body 3).In the first transition TL 1 and the second transition TL 2, the tendency to increase the excavation reaction force F continues at substantially the same rate of increase both when the approach distance AD approaches zero and when the approach distance AD exceeds zero and moves away from zero. This is because the water pipe U 1 is not present on the target trajectory TP (the first target trajectory TP 1 and the second target trajectory TP 2). The points at the first transition TL 1 and the second transition TL 2 (the values of the excavation reaction forces F) when the approach distance AD is zero mean values of the excavation reaction forces F when the tip of the blade 6 is located directly above the water passage U 1.On the other hand, the rate of increase of the third transition TL 3 clearly changes at the time when the approach distance AD reaches the value AD 0. This is because the water pipe U 1 is located on the third target trajectory TP 3 and the earth between the blade 6 and the water pipe U 1 is compressed as the claw tip of the blade 6 approaches the water pipe U 1.FIG. 6 shows a state in which the excavation reaction force F becomes F0 when the approach distance AD is AD0, and the excavation reaction force F becomes F1 when the approach distance AD is AD1. FIG. 5 shows a state in which the approach distance AD becomes the value AD 1 when the tip of the blade 6 reaches the fourth position PS 4 on the third target trajectory TP 3.In the example shown, the hidden object detection unit 32 is configured to estimate that a hidden object is present when the value of the excavation reaction force F exceeds a predetermined excavation reaction force threshold Ft. The predetermined threshold value for the excavation reaction force Ft is a value stored in advance in a nonvolatile storage device or the like. However, the predetermined threshold value for the excavation reaction force Ft may be a value that is dynamically set. For example, the predetermined threshold value for the excavation reaction force Ft may be derived based on the value of the excavation reaction force F calculated during the previous excavation operation.Alternatively, the hidden object detection unit 32 may be configured to estimate that a hidden object is present when the average increase rate of the excavation reaction force F with respect to the approach distance AD exceeds a predetermined threshold value.The hidden object detection unit 32 may be configured to estimate the presence or absence of a hidden object on the basis of the magnitude of a horizontal component or a vertical component of the excavation reaction force F.An example of an image displayed on the image display unit 41 of the display device 40 when the hidden object detection unit 32 detects the water pipe U 1 will be described herein with reference to FIG. 7. FIG. 7 is a diagram showing an example of an image output on the image display unit 41. As illustrated in FIG. 7, the image display unit 41 schematically displays a relationship between the bucket 6 and a hidden object (water pipe U 1). The object concealed / buried in the ground, for example a water pipe U1, is not actually visible. Therefore, in the example illustrated in FIG. 7, the controller 30 acquires position information of the hidden object from construction information. The construction information is stored in advance in, for example, a nonvolatile memory device. The construction information may also include two-dimensional or three-dimensional construction drawing data in addition to the position information of the hidden object.Specifically, FIG. 7 schematically illustrates the relationship between the excavation appendix AT and the hidden object when viewed directly from above with a bucket figure G 11, an arm figure G 12, a hidden object figure G 13, and an approach boundary line G 14. The output image shown in FIG. 7 shows a state immediately after the fourth excavation operation starts after the water pipe U 1 is detected by the third excavation operation shown in FIG. 5. Moreover, the output image shown in FIG. 7 shows that the finer (denser) the dot pattern is, the greater (deeper) the excavation depth is. The output image illustrated in FIG. 7 is displayed on the entire screen of the image display unit 41, but may be displayed on a portion of the image display unit 41.The blade figure G 11 is a figure illustrating a current state of the blade 6. The arm figure G 12 is a figure illustrating a current state of the arm 5. The display position, the display shape, the display size, and the like of the bucket figure G 11 and the arm figure G 12 are determined based on the output posture detection device M 1. The output image may include a boom figure representing a current state of the boom 4.The hidden object figure G 13 is a figure illustrating a position and a size of the hidden object. In the example illustrated in FIG. 7, the hidden object figure G 13 includes a hidden object figure G 13A generated based on the construction information and a hidden object figure G 13B generated based on a detection result of the hidden object detection unit 32.The approach limit line G 14 is a figure illustrating a position and a size of an approach limit range set around the hidden object. In the example illustrated in FIG. 7, as in the hidden object image G 13, the approach boundary line G 14 includes an approach boundary line G 14A corresponding to the hidden object image G 13A generated based on the construction information and an approach boundary line G 14B corresponding to the hidden object image G 13B generated based on a detection result of the hidden object detection unit 32.The display device 40 does not display the hidden object figure G 13B and the approach boundary line G 14B until the hidden object is detected by the hidden object detection unit 32. This is because the display device 40 cannot indicate display positions for the hidden object figure G 13B and the approach boundary line G 14B. On the other hand, after the hidden object is detected by the hidden object detection unit 32, the display device 40 may omit the display of the hidden object figure G 13A and the approach boundary line G 14A. This is because the hidden object represented by the hidden object figure G 13A is estimated to be actually present at the position represented by the hidden object figure G 13B.The approach limiting area is an area in which the intrusion of the predetermined portion of the excavation attachment AT is limited. In the example illustrated in FIG. 7, the approach limiting area is a space including a space in which it is determined whether the hidden object is present. The controller 30 alerts the operator that, for example, the predetermined portion of the excavation attachment AT does not enter the approach limiting area. Specifically, the controller 30 may inform the operator of the amount of the distance between the claw tip of the bucket 6 and the concealed object by outputting, for example, an intermittent sound from the sound output device 45. In this case, the controller 30 may shorten the interval of the intermittent sound as the distance decreases. When the claw tip of the bucket 6 enters the approach limiting range, the controller 30 may issue a warning to the operator via the sound output device 45. The warning is, for example, a sound that is significantly louder than the intermittent sound. The controller 30 may display to the operator the amount of distance between the claw tip of the bucket 6 and the concealed object using a bar blade.The controller 30 may autonomously control the movement of the excavation attachment AT so that the predetermined portion of the excavation attachment AT does not enter the approach limiting area. Specifically, for example, when the controller 30 determines that the claw tip of the bucket 6 will enter the approach limiting region, when the operator manually performs the arm closing operation as it is, the controller 30 may disable this arm closing operation. Alternatively, the controller 30 may automatically extend the boom cylinder 7 to raise the boom 4 so that the claw tip of the bucket 6 does not enter the approach limiting area.The controller 30 may simultaneously display the hidden object figure G 13A and the hidden object figure G 13B. This is because the degree of deviation of the hidden object from the initial position or the deformation of the hidden object is displayed to the operator in an easily comprehensible manner. The operator can estimate the deviation of another nearby hidden object by viewing such an image. Further, the operator can predict the deviation of the hidden object that may occur in the future.Further, the controller 30 may display auxiliary information represented by a dash-dot line, a double arrow, or the like. The auxiliary information may include, for example, a sub-window for displaying details of the hidden object data, a balloon image for displaying information on the to-be-lifted object taken in the bucket 6, and the like. The sub-window may indicate, for example, the time at which the buried object is buried, the type of the buried object, the material of the buried object, the size of the buried object, or the like. The balloon image may indicate, for example, the weight of the soil picked up in the bucket 6.The auxiliary information may include a vertical distance between the approach limiting area and the ground above the approach limiting area, a vertical distance between the hidden object and the ground above the hidden object, a vertical distance between the claw tip of the bucket 6 and the hidden object, a horizontal distance between the hidden object and the ground (wall surface) on the excavator 100 side, a horizontal distance between the claw tip of the bucket 6 and the hidden object, a bucket back surface angle, or the like. The blade back surface angle is an angle between a virtual plane including the back surface of the blade 6 and a virtual horizontal plane.The auxiliary information may include information on a horizontal deviation or a vertical deviation between the position of the hidden object based on the construction information and the position of the hidden object based on the detection result of the hidden object detection unit 32.The controller 30 can project an output image onto the ground as illustrated in FIG. 7 using a projector mounted on the upper swing body 3. In this case, the bucket figure G 11 and the arm figure G 12 are preferably not displayed, and the image is projected so that the actual position of the hidden object coincides with the display position of the hidden object figure G 13.Next, another configuration example of the excavation control system that can be mounted on the excavator 100 of FIG. 1 will be described with reference to FIG. 8. FIG. 8 is a diagram showing another configuration example of an excavation control system. The excavation control system of FIG. 8 is different from the excavation control system of FIG. 4 configured to detect a hidden object based on excavation reaction force mainly in that the hidden object is detected using an image captured by the front camera 70F which is one of the object detection devices 70.In the excavation control system of FIG. 8, the front camera 70F also functions as a detection device that is a device that detects information on the ground lifted by the excavation. The front camera 70F may be an imaging device attached to the excavation extension AT, such as an imaging device attached to the side surface or the inner surface e of the arm 5.The hidden object detection unit 32 is configured to be capable of detecting a hidden / buried object on the basis of information on the ground lifted by excavation. In the example illustrated in FIG. 8, the hidden / buried object detection unit 32 is configured to be capable of estimating the presence or absence of a hidden / buried object on the basis of an image captured by the front camera 70F.Here, an example of a method in which the hidden object detection unit 32 estimates the presence or absence of a hidden object will be described (see FIG. 9 ). FIG. 9 is a view showing a cross section of the ground in which the water pipe U 1 is buried as a hidden object. The position shown by the dotted circle PT 1 in FIG. 9 denotes a excavation start position, the position shown by the dotted circle PT 2 in FIG. 9 denotes a bucket claw tip position, and the position shown by the dotted circle PT 3 in FIG. 9 denotes an upland end position. In Fig. 9, for the sake of clarity, a coarse dot pattern is shown on a cross section of the ground to be excavated and a fine dot pattern is shown on a cross section of a pile of soil formed by the elevated ground.The bucket claw tip position is a position of the bucket claw tip of the bucket 6. the hidden object detection unit 32 can calculate the position of the bucket claw tip on the basis of the data output from the posture detection device M 1. The hidden object detection unit 32 can calculate the bucket claw tip position on the basis of the image captured by the front camera 70F.The excavation start position is a position at which excavation starts. In the illustrated example, the excavation start position is a bucket claw tip position when the claw tip of the bucket 6 comes into contact with the soil to be excavated. The hidden object detection unit 32 may determine whether or not the claw tip of the bucket 6 has come into contact with the ground based on the output of the excavation pressure sensor S 1. The hidden object detection unit 32 may determine whether the claw tip of the bucket 6 has come into contact with the ground based on the image captured by the front camera 70F. The hidden object detection unit 32 may calculate the excavation start position based on the image captured by the front camera 70F.The landing end position indicated by the dotted circle PT 3 in FIG. 9 denotes a position of the excavation-raised bottom edge on the side closer to the cabin 10 (upper swing body 3). In the illustrated example, the hidden object detection unit 32 may calculate the landing end position on the basis of the image captured by the front camera 70F. In this case, the hidden object detection unit 32 may determine an area of the ground (an area of the pile of soil) that has been raised by the excavation, for example, based on an image of the ground before excavation and an image of the ground during excavation. For example, the hidden object detection unit 32 may set an area in which an image change due to excavation work occurs as an area of the pile of the earth. Alternatively, the hidden object detection unit 32 may calculate distances between the front camera 70F and corresponding points on the ground based on the image captured by the front camera 70F. The hidden object detection unit 32 may set an area that has been elevated by excavation by a predetermined height or more as the area of the pile of the earth.In the illustrated example, the hidden object detection unit 32 repeatedly calculates the position of the bucket claw tip and the elevation end position in a predetermined calculation cycle. The hidden object detection unit 32 repeatedly calculates the distances DS 1, DS 2, and DS 3 in the predetermined calculation cycle based on the calculated excavation start position, the bucket claw tip position, and the earth heap end position. The hidden object detection unit 32 may omit the calculation of a distance DS 3.A distance DS 1 is a distance (horizontal distance) between the excavation start position and the bucket claw tip position in the front-rear direction, and corresponds to an "excavation length". The front-rear direction is a direction parallel to the front-rear axis of the excavator 100. The front-rear axis of the excavator 100 is an axis perpendicular to the pivot axis of the excavator 100 and perpendicular to the right-left axis of the excavator 100, and extends to bisect the excavation attachment AT in plan view. The left-right axis of the excavator 100 is an axis perpendicular to the pivot axis of the excavator 100 and perpendicular to the front-rear axis of the excavator 100. The distance DS 2 is a distance (horizontal distance) between the bucket claw tip position and the uphair end position in the front-rear direction. The distance DS 3 is a distance (vertical distance) between the starting position of the excavator and the bucket claw tip position in the up-down direction, and corresponds to a "excavation depth". The up-down direction is a direction parallel to the pivot axis of the excavator 100. The position of the claw tip that determines the distances DS 1, DS 2, and DS 3 may be replaced with a monitoring position such as the coupling pin position connecting the arm 5 and the bucket 6 or the position of the tip of the rod of the bucket cylinder 9. This is because the monitoring position is less likely to be buried in the ground than the blade claw tip position.The hidden object detection unit 32 estimates the presence or absence of a hidden / buried object on the basis of a comparison result between the distance DS 2 and a predetermined threshold value. In detail, the hidden object detection unit 32 estimates that the hidden object is present when the distance DS 2 falls below the threshold value. This is because, when the hidden object is present in the moving direction of the bucket 6, the ground is prevented from being lifted by the hidden object, and the edge (the edge including the end position of the pile of the ground represented by the dashed line circle PT 3 in FIG. 9 ) of the ground lifted by the excavation on the side closer to the cabin 10 is formed at a position closer to the bucket 6 than when the hidden object is not present.The nonvolatile storage device of the controller 30 stores in advance a correspondence between the distances DS 1 and the distance threshold value as a reference table. The hidden object detection unit 32 may repeatedly derive a distance threshold value corresponding to the calculated current distance DS 1 in the predetermined calculation cycle with reference to the reference table. In the illustrated example, the distance threshold is set to increase as the distance DS 1 increases, that is, the distance threshold is set to increase as the bucket pawl tip position moves away from the excavation start position. Note that the nonvolatile memory device of the controller 30 may store, in advance, a correspondence among the distances DS 1, the distances DS 3, and the distance thresholds as a reference table. In this case, the hidden object detection unit 32 may repeatedly derive the distance threshold value corresponding to the calculated current distance DS 1 (excavation length) and the distance DS 3 (excavation depth) in the predetermined calculation cycle. Further, the nonvolatile storage device of the controller 30 may store a plurality of reference tables in a selectable manner in consideration of differences in the shape of the bucket 6, the characteristics (viscosity, and the like) of the soil, the type of the soil, and the like. In this case, information on the shape of the bucket 6, the characteristics (viscosity and the like) of the soil, the type of the soil, and the like may be input to the controller 30 before excavation is performed.The hidden object detection unit 32 estimates the presence or absence of a hidden object by comparing the current distance DS 2 with the distance thresholds derived from the reference table. In the illustrated example, the hidden object detection unit 32 repeatedly estimates the presence or absence of a hidden object in an estimation cycle that coincides with the predetermined calculation cycle from the time when the claw tip of the bucket 6 comes into contact with the ground to the time when the claw tip of the bucket 6 is separated from the ground. For example, the hidden object detection unit 32 may determine that the claw tip of the bucket 6 is separated from the ground when the distance DS 3 becomes zero.The hidden object detection unit 32, which is a part of the excavator control system of FIG. 8, may output a control command to the control valve E 1, may output a control command to the display device 40, and may output a control command to the sound output device 45 when it is estimated that a hidden object is present, as in the case of the excavator control system of FIG. 4.The controller 30, which is a part of the excavation control system of FIG. 8, may be configured to activate the hidden object detection function in response to an activation command hidden object detection mode switch 76, as in the case of the excavation control system of FIG. 4. In the example illustrated in FIG. 8, when the hidden object detection function is activated, the hidden object detection unit 32 may estimate the presence or absence of a hidden object based on the image captured by the front camera 70F. On the other hand, the controller 30 may be configured to deactivate the hidden object detection function in response to a deactivation command of the hidden object detection mode switch 76.In the example illustrated in FIG. 8, the hidden object detection function may be configured to be executed even when the operation mode of the excavator 100 is operated in one of the M (manual) mode or the SA (semi-automatic) mode, as in the case of the excavation control system of FIG. 4, however, the hidden object detection function may be configured to be executed only when the SA (semi-automatic) mode is selected.When the SA (semi-automatic) mode is selected, an excavation operation for finding a concealed object (a series of operations from inserting the claw tip of the bucket 6 into the ground to separating the bucket 6 from the ground) can be automatically performed when the concealed object detection mode switch 76 is operated, as in the case of the excavation control system in FIG. 4.Further, the controller 30, which is a part of the excavation control system of FIG. 8, may include the excavation reaction force calculation unit 31 as in the case of the excavation control system of FIG. 4. in this case, the hidden object detection unit 32 may estimate that the hidden object is present when the value of the excavation reaction force F calculated by the excavation reaction force calculation unit exceeds a predetermined threshold value for the excavation reaction force Ft and the distance DS 2 falls below a distance threshold value.Alternatively, the hidden object detection unit 32 may start deriving the distances DS 1, DS 2 and the distance threshold value when the value of the excavation reaction force F calculated by the excavation reaction force calculation unit 31 exceeds the predetermined excavation reaction force threshold Ft. In addition, the hidden object detection unit 32 may estimate that the hidden object is present when the distance DS 2 falls below the distance threshold. However, the hidden object detection unit 32 may start calculating the excavation reaction force F when the distance DS 2 falls below the distance threshold. In addition, the hidden object detection unit 32 may estimate that the hidden object is present when the value of the excavation reaction force F exceeds the predetermined excavation reaction force threshold value Ft. This is to reduce the computational load of the controller 30.Next, an example of a process in which the hidden object detection unit 32 estimates a hidden object arrangement will be described with reference to FIG. 10. FIG. 10 comprises plan views of the excavation attachment AT during an excavation operation. A rectangle indicated by a broken line in FIG. 10 indicates an arrangement of a concealed / buried object U concealed / buried in the ground and not visible in practice. In FIG. 10, the hidden / buried object U is a rod-shaped member extending horizontally. In Fig. 10, for the sake of convenience, a coarse dot pattern is formed on the ground to be excavated, a fine dot pattern is formed on the ground pile formed by the elevated ground, and a cross pattern is formed on a hole formed by the excavation. Specifically, the left drawing of FIG. 10 shows the hidden object U (a hidden object U 11) extending leftward and rightward (perpendicular with respect to the front-rear direction) as viewed from the operator seat in the cabin 10 on the side closer to the bucket 6. The middle drawing of FIG. 10 shows the hidden object U (a hidden object U 12) hidden / buried such that a left end of the hidden object is closer to the cabin 10 than a right end of the bent object (oblique with respect to the front-rear direction). The right drawing of FIG. 10 shows the hidden object U (a hidden object U 13) hidden / buried such that the right end of the hidden object is closer to the cabin 10 than the left end of the hidden object (oblique with respect to the front-rear direction).The hidden object detection unit 32 estimates the layout of the hidden object U on the basis of information on the ground lifted by the excavation. In the illustrated example, the hidden object detection unit 32 repeatedly calculates a left end position and a right end position in a predetermined calculation cycle. The left end position means a position of an edge on the front left side (a position closest to the cab 10) of the excavation-raised floor, and the right end position means a position of an edge on the front right side (a position closest to the cab 10) of the excavation-raised floor. The term "left" means to the left of the central plane CP of the excavation extension AT, and the term "right" means to the right of the central plane CP of the excavation extension AT. The central plane CP of the attachment AT is a plane including the front-rear axis of the excavator 100 and the pivot axis of the excavator 100. In the illustrated example, the hidden object detection unit 32 may calculate the left end position and the right end position based on the image captured by the front camera 70F. The hidden object detection unit 32 repeatedly calculates the distance DS 2 (a left-side distance DS 2L and a right-side distance DS 2R) in the predetermined calculation cycle based on the calculated left end position and right end position.The left side distance DS 2L is a distance between the blade claw tip position and the left end position in the front-rear direction. The right-side distance DS 2R is a distance between the blade claw tip position and the right end position in the front-rear direction.When the hidden object detection unit 32 estimates that the hidden / buried object U exists based on the excavation reaction force and the like, the hidden object detection unit 32 estimates the arrangement of the hidden object U based on the comparison result between the link-side distance DS 2L and the right-side distance DS 2R. The hidden object detection unit 32 may simultaneously perform determination of the presence or absence of the hidden object U and estimation of the layout of the hidden object U, may estimate the layout of the hidden object U without performing the determination of the presence or absence of the hidden object U, or may perform the determination of the presence or absence of the hidden object U after the estimation of the layout of the hidden object U.For example, as illustrated in the left drawing of FIG. 10, when the difference between the left-side distance DS 2L and the right-side distance DS 2R falls below a first threshold, the hidden object detection unit 32 may estimate that the hidden object U 11 is hidden / buried so as to extend along the left-right direction. This is because, when the hidden object U is hidden / buried along the left-right direction, the shape of the ground heap on the left side of the center plane CP and the shape of the ground heap on the right side of the center plane CP are likely to be substantially the same. The left-right direction is a direction parallel to the left-right axis of the excavator 100.Alternatively, as illustrated in the middle drawing of FIG. 10, when the left-side distance DS 2L is larger than the right-side distance DS 2R and the difference between the left-side distance DS 2L and the right-side distance DS 2R is equal to or larger than a second threshold, the hidden object detection unit 32 may estimate that the hidden object U 12 is hidden / buried such that the left end is closer to the cabin 10 than the right end (oblique with respect to the front-rear direction). This is because, when the hidden object U 12 is buried as illustrated in the middle drawing of FIG. 10, the elevation on the left side of the center plane CP is likely to propagate in the front-rear direction, and the elevation on the right side of the center plane CP is likely not to propagate in the front-rear direction.Alternatively, as illustrated in the right drawing of FIG. 10, when the right-side distance DS 2R is larger than the left-side distance DS 2L and the difference between the left-side distance DS 2L and the right-side distance DS 2R is equal to or larger than a third threshold, the hidden object detection unit 32 may estimate that the hidden object U 13 is hidden / buried such that the right end is closer to the cabin 10 than the left end (oblique with respect to the front-rear direction). This is because, when the hidden object U 13 is hidden / buried as illustrated in the right drawing of FIG. 10, the ground heap on the left side of the center plane CP is less likely to spread in the front-rear direction, and the ground heap on the right side of the center plane CP is more likely to spread in the front-rear direction. The first threshold, the second threshold, and the third threshold may be the same value or may be different values.Alternatively, the hidden object detection unit 32 may repeatedly calculate a left landing end position and a right landing end position in a predetermined calculation cycle. The left-hand landing end position means a position of a left edge of the excavation-raised floor, and the right-hand landing end position means a position of a right edge of the excavation-raised floor. In the illustrated example, the hidden object detection unit 32 may calculate the left landing end position and the right landing end position based on the image captured by the front camera 70F. The hidden object detection unit 32 repeatedly calculates a left side width WDL and a right side width WDR in a predetermined calculation cycle based on the calculated left landing end position and the right landing end position.The left side width WDL is a distance between the center plane CP of the spout attachment AT and the left elevation end position in the left-right direction. The right-side width WDR is a distance between the center plane CP of the excavation extension AT and the right-hand uphole end position in the right-left direction.When the hidden object detection unit 32 estimates that the hidden object U is present based on the excavation reaction force or the like, the hidden object detection unit 32 may estimate the layout of the hidden object U based on the comparison result between the left side width WDL and the right side width WDR. The hidden object detection unit 32 can simultaneously perform determination of the presence or absence of the hidden object U and estimation of the layout of the hidden object U, can estimate the layout of the hidden object U without performing the determination of the presence or absence of the hidden object U, or can perform the determination of the presence or absence of the hidden object U after the estimation of the layout of the hidden object U.For example, as illustrated in the left drawing of FIG. 10, when the difference between the left-side width WDL and the right-side width WDR falls below the first threshold, the hidden object detection unit 32 may estimate that the hidden object U 11 is hidden / buried so as to extend along the left-right direction. This is because, when the hidden object U is hidden / buried along the left-right direction, the shape of the ground heap on the left side of the center plane CP and the shape of the ground heap on the right side of the center plane CP are likely to be substantially the same.When the left width WDL is larger than the right width WDR and the difference between the left width WDL and the right width WDR is equal to or larger than the second threshold, the hidden object detection unit 32 may detect a hidden object as in the middle drawing of FOG. Alternatively, as illustrated in FIG. 10, the hidden object U 12 is hidden / buried such that the left end is closer to the cabin 10 than the right end (oblique with respect to the front-rear direction). This is because, when the hidden object U 12 is hidden / buried as illustrated in the middle drawing of FIG. 10, the elevation on the left side of the center plane CP is likely to spread to the left side and the elevation on the right side of the center plane CP is likely not to spread to the right side.Alternatively, as illustrated in the right drawing of FIG. 10, when the right width WDR is larger than the left width WDL and the difference between the left width WDL and the right width WDR is equal to or larger than the third threshold, the hidden object detection unit 32 may estimate that the hidden object U 13 is hidden / buried such that the right end is closer to the cabin 10 than the left end (oblique with respect to the front-rear direction). When the hidden object U 13 is hidden / buried as illustrated in the right drawing of FIG. 10, the elderge on the left side of the center plane CP is less likely to spread toward the left side, and the elderge on the right side of the center plane CP is more likely to spread toward the right side. The first threshold, the second threshold, and the third threshold may be the same value or may be different values.The hidden object detection unit 32 may estimate the layout of the hidden object U based on the comparison result between the left-side distance DS 2L and the right-side distance DS 2R and the comparison result between the left-side width WDL and the right-side width WDR.The hidden object detection unit 32 may estimate the layout of the hidden object U based on the excavation reaction force information, or may estimate the layout of the hidden object U based on the excavation-raised floor information and the excavation reaction force information. For example, the hidden object detection unit 32 may estimate the layout of the hidden object U on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31 acting in the swing direction.Specifically, the hidden object estimation detection unit 32 may estimate that the hidden object U 12 is hidden / buried such that the left end is closer to the cabin 10 than the right end (oblique with respect to the front-rear direction) when the excavation reaction force acting in the left swing direction is equal to or greater than a left swing threshold. This is because, when digging the hidden object U 12, as illustrated in the middle drawing of FIG. 10, the excavation reaction force acting on the right half of the bucket 6 becomes larger than the excavation reaction force acting on the left half of the bucket 6, and a torque acts on the bucket 6 in a direction indicated by an arrow AR 1. In the example shown, the excavation reaction force acting in the left swing direction is the left swing pressure (P 17) when the left swing pressure (P 17) is greater than the right swing pressure (P 18).Similarly, the hidden object detection unit 32 may estimate that the hidden object U 13 is hidden / buried such that the right end is closer to the cabin 10 than the left end (oblique with respect to the front-rear direction) when the excavation reaction force acting in the right swing direction is equal to or greater than a right swing threshold. This is because, when digging the hidden object U 13, as illustrated in the middle drawing of FIG. 10, the excavation reaction force acting on the left half of the bucket 6 becomes larger than the excavation reaction force acting on the right half of the bucket 6, and a torque acts on the bucket 6 in a direction indicated by an arrow AR 2. In the illustrated example, the excavation reaction force acting in the right swing direction is the right swing pressure (P 18) when the right swing pressure (P 18) is larger than the left swing pressure (P 17). The left swing threshold and the right swing threshold may be the same value or may be different values.FIG. 10 shows an example of a case where the hidden object U is present in the traveling direction of the left half of the bucket 6 and the hidden object U is also present in the traveling direction of the right half of the bucket 6. However, the hidden object detection unit 32 may estimate that the hidden object U is hidden / buried so that the hidden object U is present only in the direction of travel of the left half of the blade 6 and the hidden object U is not present in the direction of travel of the right half of the blade 6 according to the same method. Moreover, the hidden object detection unit 32 may estimate that the hidden object U is buried according to the same method so that the hidden object U is present only in the traveling direction of the right half of the blade 6 and the hidden object U is not present in the traveling direction of the left half of the blade 6.Next, a control system SYS of the excavator will be described with reference to FIG. 11. FIG. 11 is a diagram showing an example of the configuration of the control system SYS of the excavator. The information acquired by the excavator 100 may be shared with a manager, an operator of another excavator, and the like via the control system SYS of the excavator as illustrated in FIG. 11.The control system SYS is a system that controls the excavator 100. In the illustrated example, the control system SYS is configured mainly by the excavator 100, a support device 200, and a management device 300. The excavator 100, the support device 200, and the management device 300 each include a communication device, and are directly or indirectly connected to each other via a mobile phone communication network, a satellite communication network, a near field communication network, or the like. The number of excavators 100, support devices 200, and management devices 300 constituting the control system SYS may be one or more, respectively. In the example of FIG. 11, the control system SYS includes an excavator 100, a support device 200, and a management device 300.The support device 200 is typically a portable terminal, for example, a computer such as a laptop PC, a tablet PC, or a smartphone that is carried by a worker or the like on a construction site. The support device 200 may be a computer worn by an operator of the excavator 100. However, the support device 200 may also be a stationary terminal device.The management device 300 is typically a stationary terminal device, for example, a server computer installed in a management center or the like outside the construction site. The management device 300 may be a portable computer (for example, a portable terminal device such as a laptop, a tablet PC, or a smartphone).At least one of the support device 200 and the management device 300 may include a monitor and an operation device for remote control. In this case, the excavator 100 and at least one of the support device 200 and the management device 300 constitute a remote control system of the excavator. The operator can operate the excavator 100 using the operating device for remote control. The remote control operation device is connected to the controller 30 via a communication network such as a mobile phone communication network, a satellite communication network, or a near field communication network. The controller 30 may be included in the support device 200 or may be included in the management device 300. All or some of the functions executed by the controller 30 may be executed by the support device 200 or the management device 300. The excavator 100 may be an unmanned excavator. In this case, the excavator 100 operates autonomously and independently of the operation performed on the operation device 26 (including an operation device for remote control).In the example illustrated in FIG. 11, the hidden object detection mode switch 76 may be provided in the support device 200 or the management device 300. The hidden object detection function may be executed by the support device 200 or the management device 300.As described above, the excavator 100 according to the embodiment of the present invention includes the lower travel body 1, the upper swing body 3 mounted on the lower travel body 1, the controller 30 mounted on the upper swing body 3, the excavation attachment AT fixed to the upper swing body 3, and the detection device that detects information on at least one of the excavation reaction force during excavation performed by the excavation attachment AT or the soil lifted by excavation. The detection device that detects information on the excavation reaction force is, for example, an excavation pressure sensor S 1. The excavation reaction force information is, for example, an analog value, a digital value, or the like representing a physical quantity used for calculating the excavation reaction force. The detection device that detects information on the excavation force may include the posture detection device M 1. The raised floor information detecting device that detects information on the ground surface is, for example, the object detecting device 70. the raised floor information is, for example, a boundary line between the raised floor and the non-raised floor, a height of the raised portion, a shape of the raised portion, a volume of the raised portion, a surface area of the raised portion, or the like. The object detection device 70 is, for example, an imaging device such as a monocular camera or a LIDAR. The detection device that detects information on the raised ground may include at least one of the posture detection device M 1 and the excavation pressure sensor S 1. The excavator 100 is configured to estimate the presence or absence of the hidden object on the basis of the information detected by the detection device.With this configuration, the excavator 100 can estimate the presence or absence of the hidden object during excavation work, and thus prevent the hidden object from being destroyed due to contact between the excavation attachment AT and the hidden object during excavation work.The excavator 100 may include the controller 30 that controls the movement of the excavation attachment AT. In this case, the controller 30 may be configured to control the movement of the excavation attachment AT so as to avoid contact between the hidden object and the excavation attachment AT when it is estimated that the hidden object is present.The controller 30 may be configured to calculate an excavation reaction force during excavation by the excavation extension AT. In this case, the detection device may be configured to detect information on the ground lifted by the excavation. The controller 30 may be configured to estimate the presence or absence of the hidden object on the basis of the excavation reaction force and / or the information detected by the detection device.With this configuration, even when the operator of the excavator 100 manually brings the excavation attachment AT close to the hidden object, the controller 30 can move the excavation attachment AT away from the hidden object or stop the movement of the excavation attachment AT. Thereby, the controller 30 can more reliably prevent the hidden object from being destroyed due to contact between the excavation extension AT and the hidden object during excavation work.The excavator 100 may be configured to notify an outsider of the presence of the hidden object when the presence of the hidden object is estimated. For example, as illustrated in FIG. 4, the hidden object detection unit 32 may output a control command to the controller 30 at least at one of the display device 40 and the sound output device 45 when the presence of the hidden object is estimated, and visually or auditively notify the operator of the excavator 100 that the hidden object is present near the claw tip of the bucket 6.With this configuration, the controller 30 can more reliably prevent the hidden object from being destroyed due to contact between the excavation attachment AT and the hidden object during excavation work.The excavator 100 may be configured to estimate the presence or absence of a hidden object on the basis of at least one of the excavation reaction force calculated when the excavation attachment AT is moved along a predetermined trajectory to perform excavation and the excavation-raised-ground information. For example, the hidden object detection unit 32 of the controller 30 may be configured to estimate the presence or absence of a hidden object on the basis of a comparison result between the excavation reaction force calculated by the excavation reaction force calculation unit 31 and the excavation reaction force threshold value when the claw tip of the blade 6 moves along the target trajectory TP. Alternatively, the hidden object detection unit 32 may be configured to estimate the presence or absence of the hidden object on the basis of the comparison result between the distance DS 2 calculated when the claw tip of the blade 6 moves along the target trajectory TP and the distance threshold. Alternatively, the hidden object detection unit 32 may be configured to estimate the presence or absence of a hidden object on the basis of the comparison result between the excavation reaction force calculated when the claw tip of the blade 6 moves along the target trajectory TP and the excavation reaction force threshold value and the comparison result between the distance DS 2 calculated when the claw tip of the blade 6 moves along the target trajectory TP and the distance threshold value.The excavator 100 may be configured to estimate the presence or absence of a hidden object on the basis of at least one of an excavation reaction force generated when the bucket 6, which is a part of the excavation attachment AT, is moved in a direction approaching a body of the upper swing body 3 to perform excavation and information on the ground lifted by the excavation. For example, as illustrated in FIG. 5, the hidden object detection unit 32 of the controller 30 may be configured to estimate the presence of a hidden object when the excavation reaction force F calculated when the claw tip of the blade 6 moves toward the body of the upper swing body 3 along the target trajectory TP exceeds the predetermined excavation reaction force threshold Ft (see FIG. 6 ). Alternatively, as illustrated in FIG. 9, the hidden object detection unit 32 may be configured to estimate the presence of a hidden object when the distance DS 2 calculated when the claw tip of the blade 6 moves in the direction of the upper swing body 3 falls below the distance threshold. Alternatively, the hidden object detection unit 32 may be configured to estimate the presence of a hidden object when the excavation reaction force F calculated when the claw tip of the bucket 6 moves toward the body of the upper swing body 3 along the target trajectory TP exceeds the excavation reaction force threshold value Ft and the distance DS 2 calculated when the claw tip of the bucket 6 moves toward the body of the upper swing body 3 falls below the distance threshold value.With this configuration, the excavator 100 can accurately estimate the presence or absence of the hidden object and thus more reliably prevent the hidden object from being destroyed due to contact between the excavation attachment AT and the hidden object during excavation work.In the above-described embodiment, the hidden object detection unit 32 is configured to estimate the presence or absence of a hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31 when the claw tip of the blade 6 moves along the target trajectory TP. However, the hidden object detection unit 32 may be configured to estimate the presence or absence of a hidden object on the basis of the excavation reaction force calculated by the excavation reaction force calculation unit 31 when the claw tip of the blade 6 moves independently of a predetermined trajectory such as the target trajectory TP.As illustrated in FIG. 1, an excavator 100 according to the embodiment of the present invention includes a lower travel body 1, an upper swing body 3 mounted on the lower travel body 1, an excavation extension AT attached to the upper swing body 3, and a detection device that detects information on at least one of an excavation reaction force during excavation by the excavation extension AT and a ground lifted by the excavation. The detection device that detects information on the excavation reaction force is, for example, the excavation pressure sensor S 1. The detection device that detects information on the excavation reaction force may include the posture detection device M 1. The detection device that detects information on the ground surface is, for example, the object detection device 70. the object detection device 70 is, for example, an imaging device such as a monocular camera or a LIDAR. The excavator 100 is configured to estimate the arrangement of the hidden object U on the basis of the information detected by the detection device.With this configuration, the excavator 100 can estimate the arrangement of the hidden object U during excavation work, and thus prevent the hidden object U from being destroyed due to contact between the excavation attachment AT and the hidden object U during excavation work.Further, as illustrated in FIG. 10, the excavation-raised-ground information may include information on a region of a part of the excavation formed by the excavation-raised ground, the part being located on the left side of the center plane CP of the excavation attachment AT extending in the front-rear direction, and information on a region of a part of the excavation formed by the excavation-raised ground, the part being located on the right side of the center plane CP.The excavation reaction force during excavation information performed by the excavation extension AT may include excavation reaction force information acting in the swing direction.With these configurations, the excavator 100 can more accurately estimate the location of the hidden object U in the ground. For example, the excavator 100 may estimate whether or not the hidden object U is obliquely buried with respect to the front-rear direction. Alternatively, the excavator 100 may estimate whether the distance between the left end of the bucket 6 and the concealed object U in the front-rear direction is greater than or less than the distance between the right end of the bucket 6 and the concealed object U in the front-rear direction. Alternatively, the excavator 100 may estimate that the hidden object U is present in the travel direction of the left half of the bucket 6 and that the hidden object is absent in the travel direction of the right half of the bucket 6.Although the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention.DESCRIPTION OF THE REFERENCE NUMERALS1 Lower traveling body 1A Left traveling hydraulic motor 1B Right traveling hydraulic motor 2 Swing mechanism 2A Swing hydraulic motor 3 Upper swinging body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cab 11 Motor 11 a Licht 11 b Starter 11 c Kühlmittel temperature sensor 14 Main pump 14 a Regler 14 b Abgabe pressure sensor 14 cOil temperature sensor 15 Pilot pump 15 a, 15 b Pressure sensor 16 Hydraulic fluid line 17 Control valve unit 25, 25 a Vorsteuer line 26 Operating device 26A, 26B Lever 26C Pedal 30 Controller 30 a Vorübergehende storage unit 31 Excavation reaction force calculation unit 32 Hidden object detection unit 40 Display device 41 Image display unit 42 Input unit 45 Sound output device 70 Object detection device 72 Electric component 74 Motor control device 75 Operation mode switching switch 76 Hidden object detection mode switching switch 90 Storage battery 100 Excavator 200 Support device 300 Management device E 1 Control valve M 1 Posture detection device M 1 a Ausleger angle sensor M 1 bArm angle sensor M 1 c Shovel angle sensor S 1, S 11-S 18 Excavation pressure sensor SYS Control system U 1 Water pipe

Claims

A control device for an excavator, the control device comprising: a detection device configured to detect information on a excavation-raised ground, wherein the control device estimates presence or absence of a hidden object on the basis of at least one of an excavation reaction force calculated during excavation by an excavation attachment of the excavator or information detected by the detection device.The control device according to claim 1, wherein the control device controls a movement of the excavation attachment to avoid contact between the hidden object and the excavation attachment when the presence of the hidden object is estimated.The control device according to claim 1, wherein the control device notifies an outside of the presence of the concealed object when the presence of the concealed object is estimated.The control device according to claim 1, wherein the control device estimates the presence or absence of the hidden object on the basis of at least one of an excavation reaction force calculated when the excavation attachment is moved along a predetermined trajectory to perform excavation or the excavation-raised ground information.The control device according to claim 1, wherein the control device estimates the presence or absence of the hidden object on the basis of at least one of an excavation reaction force generated when a bucket that is a part of the excavation attachment is moved in a direction approaching a body of the excavator to perform excavation or the excavation-raised-ground information.A control device for an excavator, the control device comprising: a detection device configured to detect excavation-raised ground information, wherein the control device estimates an arrangement of a hidden object on the basis of at least one of the excavation reaction force during excavation by an excavation attachment of the excavator or information detected by the detection device.The control device according to claim 6, wherein the excavation-raised-ground information includes information on an area of a portion of an excavation formed by the excavation-raised ground, the portion being located on a left side of a central plane of the excavation extension piece extending in a front-rear direction, and information on an area of another portion of the excavation formed by the excavation-raised ground, the other portion being located on a right side of the central plane.The control device according to claim 6, wherein the excavation reaction force during excavation by the excavator attachment includes an excavation reaction force acting in a swing direction.An excavator comprising: the control device according to any one of claims 1 to 8; a lower travel body; an upper swing body mounted on the lower travel body; and an excavation attachment attached to the upper swing body.

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