CONTROL SYSTEM FOR WORK MACHINE, CONTROL METHOD FOR WORK MACHINE, AND REMOTE OPERATION SYSTEM FOR WORK MACHINE

Description

TECHNICAL FIELD

The present disclosure relates to a control system for a work machine, a control method for a work machine, and a remote operation system for a work machine.

Priority is claimed on Japanese Patent Application No. 2023-123066, filed Jul. 28, 2023, the content of which is incorporated herein by reference.

BACKGROUND ART

Patent Document 1 discloses a technique related to a work machine that performs an automatic excavation process.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Excavation work and soil dumping work using a work machine including a work implement supported by a revolving body are usually carried out by driving the work implement without allowing the revolving body to revolve. On the other hand, the revolving body may revolve depending on the environment even though the revolving body is not operated to revolve during the work. For example, when excavation, such as excavation of a wall surface of a trench, is performed using one side of the bucket, a load applied to the bucket may be unbalanced between the left and right sides, resulting in a moment being generated at the rotation center of the revolving body receiving a reaction force, which could cause the revolving body to revolve. In addition, when the work machine is stopped on a slope, a moment may occur due to gravity, which could cause the revolving body to revolve.

An object of the present disclosure is to provide a control system for a work machine, a control method for a work machine, and a remote operation system for a work machine capable of preventing unintended revolution from occurring during work.

Solution to Problem

According to an aspect of the present invention, a control system for a work machine is a control system for a work machine including a revolving body that can rotate about a revolution center, a work implement attached to the revolving body, and a revolution braking device that stops revolution of the revolving body, the control system including a brake control unit that actuates the revolution braking device when the work implement is driven with no operation of the revolving body.

Advantageous Effects of Invention

According to the above aspect, the control system for a work machine can prevent unintended revolution from occurring during work of a work machine.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A schematic diagram illustrating a configuration of a work machine according to a first embodiment.

FIG. 2 A diagram illustrating an internal configuration of a cab according to the first embodiment.

FIG. 3 A schematic diagram illustrating a configuration of a revolution parking brake according to the first embodiment.

FIG. 4 A schematic block diagram illustrating a configuration of a control device according to the first embodiment.

FIG. 5 A diagram illustrating an example of a target trajectory according to the first embodiment.

FIG. 6 A flowchart showing an automatic excavation control method according to the first embodiment.

FIG. 7 A diagram illustrating a configuration of a revolution motor according to a second embodiment.

FIG. 8 A flowchart showing an automatic excavation control method according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference to the drawings.

First Embodiment

Configuration of Work Machine 100

FIG. 1 is a schematic diagram illustrating a configuration of a work machine 100 according to a first embodiment. The work machine 100 according to the first embodiment performs automatic excavation control following instructions of an operator. The automatic excavation control is control for automatically executing an operation of excavating soil and sand by driving a boom 131, an arm 132, and a bucket 133 with the blade edge of the bucket 133 being disposed at an excavation start position on an excavation target. That is, the work machine 100 under the automatic excavation control drives a work implement 130, without outputting operation signals for a traveling body 110 and a revolving body 120.

The work machine 100 operates at construction sites, excavates a construction target such as soil and sand, and loads the construction target as a load onto a loading platform such as a vessel of a loading target such as a dump truck. Examples of the work machine 100 include a face shovel, a backhoe shovel, a rope shovel, and the like. Furthermore, the work machine 100 may be electrically driven or may be hydraulically driven. The work machine 100 according to the first embodiment is a backhoe shovel. The work machine 100 includes the traveling body 110, the revolving body 120, the work implement 130, and the cab 140. Examples of the loading target include a dump truck, a hopper, and the like.

The traveling body 110 supports the work machine 100 so that the work machine 100 can travel. The traveling body 110 includes two endless tracks 111 provided on left and right sides and two travel motors 112 for driving the endless tracks 111, respectively. The traveling body 110 is an example of a support part.

The revolving body 120 is supported by the traveling body 110 such that the revolving body can revolve about a revolution center.

The work implement 130 is driven by hydraulic pressure. The work implement 130 is supported at a front portion of the revolving body 120 such that the work implement can be driven in the longitudinal direction.

The cab 140 is a space where an operator boards and operates the work machine 100. The cab 140 is provided at a left front portion of the revolving body 120.

Here, a portion of the revolving body 120 where the work implement 130 is attached is referred to as a front portion. In addition, in the revolving body 120, with reference to the front portion, a portion on a side opposite thereto is referred to as a rear portion, a portion on the left side is referred to as a left portion, and a portion on the right side is referred to as a right portion.

Configuration of Revolving Body 120

The revolving body 120 includes an engine 121, a hydraulic pump 122, a control valve 123, a revolution motor 124, and a revolution parking brake 125.

The engine 121 is a prime mover that drives the hydraulic pump 122. The engine 121 is an example of a power source.

The hydraulic pump 122 is a variable displacement pump driven by the engine 121. The hydraulic pump 122 supplies hydraulic oil to actuators (a boom cylinder 131C, an arm cylinder 132C, a bucket cylinder 133C, the travel motor 112, and the revolution motor 124) via the control valve 123.

The control valve 123 controls a flow rate of the hydraulic oil supplied from the hydraulic pump 122.

The revolution motor 124 is driven by the hydraulic oil supplied from the hydraulic pump 122 via the control valve 123 to cause the revolving body 120 to revolve.

The revolution parking brake 125 can stop revolution of the revolving body 120 with a mechanical braking force. The revolution parking brake 125 stops rotation of the revolving body 120 with respect to the traveling body 110. The revolution parking brake 125 may be, for example, a disc brake. The revolution parking brake 125 is a hydraulic negative brake, and the brake is released by introducing pressure oil from a brake solenoid valve 1253. The revolution parking brake 125 is an example of a revolution braking device that stops revolution of the revolving body 120.

Configuration of Work Implement 130

The work implement 130 includes a boom 131, an arm 132, a bucket 133 as a work tool, a boom cylinder 131C, an arm cylinder 132C, and a bucket cylinder 133C. Other examples of the work tool include distal end attachments such as a clamshell bucket, a tilt bucket, a tilt rotator bucket, a grapple, and a lifting magnet.

A base end portion of the boom 131 is rotatably attached to the revolving body 120 via a boom pin. Note that, although the boom 131 is provided at a front center portion of the revolving body 120 in the work machine 100 illustrated in FIG. 1, it is not limited thereto, and the boom 131 may be attached with an offset in the lateral direction. In this case, the revolution center of the revolving body 120 is not located on an operation plane of the work implement 130.

The arm 132 couples the boom 131 and the bucket 133. A base end portion of the arm 132 is rotatably attached to a distal end portion of the boom 131 via an arm pin.

The bucket 133 is rotatably attached to a distal end portion of the arm 132 via a pin. The boom 131 and the arm 132 are members that support the bucket 133. The bucket 133 serves as a container for accommodating excavated soil and sand. The bucket 133 is attached with an opening thereof facing the revolving body 120 side (rearward). That is, the work machine 100, which is a backhoe shovel, performs excavation by pulling the bucket 133 toward the front side of the revolving body 120.

The boom cylinder 131C is a hydraulic cylinder for actuating the boom 131. A base end portion of the boom cylinder 131C is attached to the revolving body 120. A distal end portion of the boom cylinder 131C is attached to the boom 131.

The arm cylinder 132C is a hydraulic cylinder for driving the arm 132. A base end portion of the arm cylinder 132C is attached to the boom 131. A distal end portion of the arm cylinder 132C is attached to the arm 132.

The bucket cylinder 133C is a hydraulic cylinder for driving the bucket 133. A base end portion of the bucket cylinder 133C is attached to the arm 132. A distal end portion of the bucket cylinder 133C is attached to a link mechanism that rotates the bucket 133.

Configuration of Cab 140

FIG. 2 is a diagram illustrating an internal configuration of the cab 140 according to the first embodiment.

An operator seat 141, an operation terminal 142, an operation device 143, and a revolution lock switch 144 are provided in the cab 140. The operation terminal 142 is provided in the vicinity of the operator seat 141 and is a user interface with a control device 160 described below. The operation terminal 142 is a display device constituted by a touch panel, for example, and may include an operation unit to be operated by an operator and an input reception unit that receives operations. Furthermore, the display device displays measurement data of an engine water temperature gauge, a fuel gauge, and the like. In addition, the operation terminal 142 may include a display unit such as an LCD.

The operation device 143 is a device for driving the traveling body 110, the revolving body 120, and the work implement 130 through manual operations by the operator. The operation device 143 includes a left operation lever 143LO, a right operation lever 143RO, a left foot pedal 143LF, a right foot pedal 143RF, a left travel lever 143LT, a right travel lever 143RT, and a start switch 143SW.

The left operation lever 143LO is provided on the left side of the operator seat 141. The right operation lever 143RO is provided on the right side of the operator seat 141.

The left operation lever 143LO is an operation mechanism for performing a revolution operation of the revolving body 120 and an excavation/dumping operation of the arm 132. Specifically, when the operator of the work machine 100 tilts the left operation lever 143LO forward, the arm 132 performs the dumping operation. In addition, when the operator of the work machine 100 tilts the left operation lever 143LO rearward, the arm 132 performs the excavation operation. Furthermore, when the operator of the work machine 100 tilts the left operation lever 143LO rightward, the revolving body 120 revolves to the right. In addition, when the operator of the work machine 100 tilts the left operation lever 143LO leftward, the revolving body 120 revolves to the left. Note that, in another embodiment, the revolving body 120 may revolve to the right or the left when the left operation lever 143LO is tilted in a front-rear direction, and the arm 132 may perform the excavation operation or the dumping operation when the left operation lever 143LO is tilted in the left-right direction.

The right operation lever 143RO is an operation mechanism for performing the excavation/dumping operation of the bucket 133 and the excavation/dumping operation of the boom 131. Specifically, when the operator of the work machine 100 tilts the right operation lever 143RO forward, the excavation operation of the boom 131 is performed. In addition, when the operator of the work machine 100 tilts the right operation lever 143RO rearward, the dumping operation of the boom 131 is performed. Furthermore, when the operator of the work machine 100 tilts the right operation lever 143RO rightward, the dumping operation of the bucket 133 is performed. In addition, when the operator of the work machine 100 tilts the right operation lever 143RO leftward, the excavating operation of the bucket 133 is performed. Note that, in another embodiment, the bucket 133 may perform the dumping operation or the excavation operation when the right operation lever 143RO is tilted in the front-rear direction, and the boom 131 may perform the excavation operation or the dumping operation when the right operation lever 143RO is tilted in the left-right direction.

The left foot pedal 143LF is disposed on the left side of the floor surface in front of the operator seat 141. The right foot pedal 143RF is disposed on the right side of the floor surface in front of the operator seat 141. The left travel lever 143LT is pivotally supported by the left foot pedal 143LF and is configured such that an inclination of the left travel lever 143LT and a depression of the left foot pedal 143LF are linked with each other. The right travel lever 143RT is pivotally supported by the right foot pedal 143RF and is configured such that an inclination of the right travel lever 143RT and a depression of the right foot pedal 143RF are linked with each other.

The left foot pedal 143LF and the left travel lever 143LT correspond to a rotational drive of the left crawler track of the traveling body 110. Specifically, when the operator of the work machine 100 tilts the left foot pedal 143LF or the left travel lever 143LT forward, the left crawler track rotates in the forward traveling direction. Furthermore, when the operator of the work machine 100 tilts the left foot pedal 143LF or the left travel lever 143LT rearward, the left crawler track rotates in the rearward traveling direction.

The right foot pedal 143RF and the right travel lever 143RT correspond to a rotational drive of the right crawler track of the traveling body 110. Specifically, when the operator of the work machine 100 tilts the right foot pedal 143RF or the right travel lever 143RT forward, the right crawler track rotates in the forward traveling direction. In addition, when the operator of the work machine 100 tilts the right foot pedal 143RF or the right travel lever 143RT rearward, the right crawler track rotates in the rearward traveling direction.

The start switch 143SW is provided, for example, at a handle portion of the left operation lever 143LO. Note that the start switch 143SW is disposed to be located in the vicinity of the operator seated on the operator seat 141. When the start switch 143SW is operated, an excavation instruction signal is output to the control device 160. Upon receiving an input of the excavation instruction signal, the control device 160 starts automatic excavation control.

The revolution lock switch 144 is provided in the vicinity of the operator seat 141. The revolution lock switch 144 is an alternate switch manually operated by the operator to bring the revolution parking brake 125 into either an actuated state or a released state. When the revolution lock switch 144 is in an ON state, the revolution parking brake 125 is in the actuated state, and the revolving body 120 does not revolve. The revolution lock switch 144 is manually switched to the ON state when it is desired to stop and hold the revolving body 120. When the revolution lock switch 144 is in an OFF state, the revolution parking brake 125 is in the released state, and the revolving body 120 can revolve.

For example, once the revolution lock switch 144 is operated by the operator to bring the revolution parking brake 125 into the actuated state, the revolution parking brake 125 is actuated and the revolution of the revolving body 120 is stopped. When the revolution parking brake 125 is actuated, the revolving body 120 does not revolve even if the left operation lever 143LO is operated to make the revolving body 120 perform a revolving operation. For example, when the work implement 130 is operated in a manual mode without causing the revolving body 120 to revolve, the operator operates the revolution lock switch 144. When the revolving body 120 does not revolve, it is highly likely that the left operation lever 143LO for causing the revolving body 120 to revolve is in a neutral state. When the work machine 100 works on, for example, an inclined surface, if the left operation lever 143LO is in the neutral state, it is likely that the revolving body 120 revolves due to its own weight. Even when the left operation lever 143LO is in the neutral state due to actuation of the revolution parking brake 125 by the operation of the revolution lock switch 144, the revolution of the revolving body 120 is prevented.

Configuration of Revolving Brake

FIG. 3 is a schematic diagram illustrating a configuration of the revolution parking brake 125 according to the first embodiment.

The revolution parking brake 125 includes a brake cylinder 1251, a pair of brake discs 1252, and a brake solenoid valve 1253.

The revolution lock switch 144 is disposed between the control device 160 and the brake solenoid valve 1253. The control device 160 receives either or both of an input signal indicating that the revolution lock switch 144 has been operated to bring the revolution parking brake 125 into the actuated state and an input signal indicating that the revolution lock switch 144 has been operated to bring the revolution parking brake 125 into the released state.

The brake cylinder 1251 is a spring-loaded hydraulic cylinder driven by hydraulic oil. The brake cylinder 1251 is normally in a pushed-out state, and the rod is retracted when the hydraulic oil is supplied to the rod side.

The brake discs 1252 are provided at the distal end of the rod of the brake cylinder 1251. The brake discs 1252 come into contact with a revolution motor 124 when the rod is pushed out and lock the rotation of the revolution motor 124. The brake discs 1252 move away from the revolution motor 124 when the rod is retracted and release the revolution motor 124. That is, the revolution parking brake 125 is released by supplying hydraulic oil to the oil chamber on the rod side of the brake cylinder 1251. When the brake solenoid valve 1253 is driven and the brake cylinder 1251 is contracted, the pair of brake discs 1252 are separated from each other, and the actuation of the revolution parking brake 125 is released. Once the drive of the brake solenoid valve 1253 is stopped, the brake cylinder 1251 extends by the elastic force of a spring provided at the brake cylinder 1251. When the brake cylinder 1251 extends, the pair of brake discs 1252 come into contact with each other, leading to actuation of the revolution parking brake 125.

The brake solenoid valve 1253 controls the actuation and release of the revolution parking brake 125. When the brake solenoid valve 1253 is switched to the ON state, the brake solenoid valve 1253 is driven to set the valve position to an open state, bringing the revolution parking brake 125 to an open state. The brake solenoid valve 1253 releases the revolution parking brake 125 when magnetized, and actuates the revolution parking brake 125 when de-magnetized.

The brake solenoid valve 1253 is electrically connected to the control device 160, which will be described below, via the revolution lock switch 144.

When the revolution lock switch 144 is in the OFF state, the brake solenoid valve 1253 is always magnetized to release the revolution parking brake 125, so the revolution lock is released. When the revolution lock switch 144 is in the ON state, a brake actuation signal from the control device 160 is supplied to the brake solenoid valve 1253, and thus the brake solenoid valve 1253 is de-magnetized, the revolution parking brake 125 is actuated, blocking revolution.

Configuration of Measurement System

The work machine 100 includes a position and orientation calculator 151, an inclination measuring instrument 152, a boom stroke sensor 153, an arm stroke sensor 154, and a bucket stroke sensor 155, and a shape detection device 156 as illustrated in FIG. 1.

The position and orientation calculator 151 calculates a position of the revolving body 120 and an orientation in which the revolving body 120 is directed. The position and orientation calculator 151 includes two receivers that receive positioning signals from artificial satellites constituting the global navigation satellite system (GNSS). The two receivers are installed at different positions on the revolving body 120. The position and orientation calculator 151 detects a position of a representative point (origin of shovel coordinate system) of the revolving body 120 in a site coordinate system based on the positioning signals received by the receivers.

Using the positioning signals received by the two receivers, the position and orientation calculator 151 calculates the orientation in which the revolving body 120 is directed as a relationship between an installation position of one receiver and an installation position of the other receiver. The orientation in which the revolving body 120 is directed is a direction orthogonal to the front surface of the revolving body 120. The orientation in which the revolving body 120 is directed is equal to a horizontal component in an extending direction of a straight line extending from the boom 131 to the bucket 133 of the work implement 130.

The inclination measuring instrument 152 measures an acceleration and an angular velocity of the revolving body 120, and detects a posture (for example, roll angle, pitch angle, and yaw angle) and a revolution speed of the revolving body 120 based on the measurement result. The inclination measuring instrument 152 is installed, for example, on a lower surface of the revolving body 120. As the inclination measuring instrument 152, an inertial measurement unit (IMU) can be used, for example.

The boom stroke sensor 153 is attached to the boom cylinder 131C and detects a cylinder length of the boom cylinder 131C. The cylinder length of the boom cylinder 131C can be converted into a relative angle of the boom 131 with respect to the revolving body 120.

The arm stroke sensor 154 is attached to the arm cylinder 132C and detects a cylinder length of the arm cylinder 132C. The cylinder length of the arm cylinder 132C can be converted into a relative angle of the arm 132 with respect to the boom 131.

The bucket stroke sensor 155 is attached to the bucket cylinder 133C and detects a cylinder length of the bucket cylinder 133C. The cylinder length of the bucket cylinder 133C can be converted into a relative angle of the bucket 133 with respect to the arm 132.

The work machine 100 according to the first embodiment identifies an angle of each link component of the work implement 130 using the boom stroke sensor 153, the arm stroke sensor 154, and the bucket stroke sensor 155, but is not limited thereto in other embodiments. For example, in another embodiment, a potentiometer that detects a relative rotation angle of a link component may be provided, or an inclination sensor that detects a ground angle of each link component may be provided instead of the stroke sensor.

The shape detection device 156 detects the position and surface shape of an object present in the detection direction. Examples of the shape detection device 156 include a stereo camera, a laser scanner, and the like. The shape detection device 156 is provided such that the detection direction is directed toward the front side of the cab 140 of the work machine 100, for example. The shape detection device 156 identifies a surface shape of a target object in a coordinate system using a position of the shape detection device 156 as a reference. Note that the shape detection device 156 according to another embodiment may specify the surface shape of a target object with reference to the vehicle body coordinate system based on the dimension value obtained by measuring the attachment position of the shape detection device 156 in advance with reference to the vehicle body coordinate system. Furthermore, the shape detection device 156 according to another embodiment may specify the surface shape of a target object with reference to the on-site coordinate system based on the dimension value obtained by measuring the attachment position of the shape detection device 156 in advance with reference to the vehicle body coordinate system, and the position and posture information of the vehicle body in the on-site coordinate system.

Configuration of Control Device 160

FIG. 4 is a schematic block diagram illustrating a configuration of the control device 160 according to the first embodiment.

The work machine 100 includes the control device 160. The control device 160 may be mounted on the operation terminal 142, or may be provided separately from the operation terminal 142 and receive inputs and outputs from the operation terminal 142. The control device 160 receives operation signals from the operation device 143. The control device 160 drives the work implement 130, the revolving body 120, and the traveling body 110 by outputting the received operation signal or an operation signal generated for automatic control to the control valve 123. Hereinafter, the operation signal received from the operation device 143 is referred to as a manual operation signal, and the operation signal generated for automatic control is referred to as an automatic operation signal. Note that the automatic operation signal is composed of operation signals for driving the revolving body 120 and the work implement 130, and does not include an operation signal for driving the traveling body 110. When a manual operation signal from the operator is received during automatic control, the control device 160 may stop the automatic control.

The control device 160 is a computer including a processor 610, a main memory 630, a storage 650, and an interface 670. The storage 650 stores a program. The processor 610 reads the program from the storage 650, loads the program into the main memory 630, and executes processing according to the program.

Examples of the storage 650 include a semiconductor memory, a magnetic disk, a magneto-optical disc, an optical disc, and the like. The storage 650 may be an internal medium directly connected to a common communication line of the control device 160, or may be an external medium connected to the control device 160 via the interface 670. The main memory 630 and the storage 650 are non-transitory tangible storage media.

For execution of the program, the processor 610 includes a measurement data acquisition unit 611, an operation signal input unit 612, a work implement positioning unit 613, a trajectory generation unit 614, a movement control unit 615, a revolution determination unit 616, a brake control unit 617, and an operation signal output unit 618.

The measurement data acquisition unit 611 acquires, for example, the revolution speed, the position, and the orientation of the revolving body 120, the inclination angles of the boom 131, the arm 132, and the bucket 133, the posture of the revolving body 120, and the surface shape of the environment of the work machine 100. Note that the surface shape of the environment of the work machine 100 includes the surface shape of the excavation target.

The measurement data acquisition unit 611 acquires measurement data acquired by the measurement system of the work machine 100. Specifically, the measurement data acquisition unit 611 acquires measurement data from each of the position and orientation calculator 151, the inclination measuring instrument 152, the boom stroke sensor 153, the arm stroke sensor 154, the bucket stroke sensor 155, and the shape detection device 156. The measurement data acquisition unit 611 calculates an angle of the revolving body 120 by integrating the angular velocity of the revolving body 120 measured by the inclination measuring instrument 152.

The operation signal input unit 612 receives input of manual operation signals manually operated by the operator from the operation device 143. The manual operation signals include a drive signal for performing a dumping operation or an excavation operation of the boom 131, a drive signal for performing a dumping operation or an excavation operation of the arm 132, a drive signal for performing a dumping operation or an excavation operation of the bucket 133, a drive signal for performing a right revolution operation or a left revolution operation of the revolving body 120, a drive signal for performing a travel operation of the traveling body 110, and an excavation instruction signal for the work machine 100.

The work implement positioning unit 613 identifies the position of the blade edge of the bucket 133 in a vehicle coordinate system with reference to the revolving body 120 based on the measurement data acquired by the measurement data acquisition unit 611.

The work implement positioning unit 613 calculates the vertical direction component and the horizontal direction component of the length of the boom 131 based on an inclination angle of the boom 131 and a known length of the boom 131 (distance from the pin at the base end portion to the pin at the distal end portion). Similarly, the work implement positioning unit 613 calculates the vertical direction component and the horizontal direction component of the length of the arm 132. Furthermore, the work implement positioning unit 613 calculates the vertical direction component and the horizontal direction component from the pin to the blade edge of the bucket 133 based on an inclination angle of the bucket 133 and a known shape of the bucket 133. The work implement positioning unit 613 identifies the position separated from the position of the work machine 100 by the sum of the vertical direction components and the sum of the horizontal direction components of the lengths of the boom 131, the arm 132, and the bucket 133 in the direction identified from the orientation and the posture of the work machine 100 as the position of the blade edge of the bucket 133.

The trajectory generation unit 614 generates a target trajectory T of the bucket 133 based on the position of the blade edge of the bucket 133 specified by the work implement positioning unit 613 when an excavation instruction signal is input and the measurement data of the shape detection device 156. FIG. 5 is a diagram illustrating an example of a target trajectory according to the first embodiment. The target trajectory T of the bucket 133 is drawn as a trajectory of the blade edge of the bucket 133 excavating an excavation target in the excavation direction from the position of the blade edge when an excavation instruction signal is input. In the backhoe shovel, the excavation direction is the backward direction of the revolving body 120. The shape of the target trajectory T according to the first embodiment is an arc. The target trajectory T is a target trajectory when only the work implement is operated to perform excavation without a revolving operation. The target trajectory T of the bucket 133 draws an arc according to a predetermined excavation curve ratio as illustrated in FIG. 5. The excavation curve ratio is a value expressed as a ratio of an excavation depth D to an excavation length L (D/L). The lower the excavation curve ratio, the longer the excavation length L and the shallower the excavation depth D. The higher the excavation curve ratio, the shorter the excavation length L and the deeper the excavation depth D. A method of specifying an excavation curve ratio will be described below. The trajectory generation unit 614 generates the target trajectory T of the bucket 133 such that the excavation amount when excavation is performed in accordance with the generated target trajectory T is calculated and the excavation amount is equal to the maximum storage capacity of the bucket 133. Note that the shape of the target trajectory T according to other embodiments may be any curve having a downward convex shape such as an elliptical arc, a parabola, and a gentle curve having no inflection point.

When the operation signal input unit 612 receives input of an excavation instruction signal, the movement control unit 615 generates an automatic operation signal for moving the blade edge of the bucket 133 along the target trajectory T.

The revolution determination unit 616 determines whether revolution not intended by the operator has occurred based on the difference between the orientation of the revolving body 120 at the time of the start of automatic excavation control measured by the position and orientation calculator 151 and the current orientation of the revolving body 120. For example, the orientation of the revolving body 120 refers to a posture of the revolving body.

The brake control unit 617 switches on/off a brake release signal supplied to the brake solenoid valve 1253. The brake release signal is a binary signal having either an ON value or an OFF value. When the value of the brake release signal is OFF, the revolution parking brake 125 is actuated, and when the value of the brake release signal is ON, the revolution parking brake 125 is released. The brake control unit 617 sets the value of the brake release signal to OFF when revolution not intended by the operator occurs. When the automatic excavation control is ended, the brake control unit 617 sets the value of the brake release signal to ON.

The operation signal output unit 618 outputs a manual operation signal input to the operation signal input unit 612 or an automatic operation signal generated by the movement control unit 615. Specifically, the operation signal output unit 618 outputs the automatic operation signal generated by the movement control unit 615 and the brake control unit 617 when the automatic excavation control is being performed, and outputs the manual operation signal input to the operation signal input unit 612 when the automatic excavation control is not being performed.

Operation

When the operator of the work machine 100 moves the blade edge of the bucket 133 to the excavation start position, the operator operates the start switch 143SW. The operation device 143 thereby generates and outputs an excavation instruction signal. The excavation start position is a position on the surface of an excavation target.

When the control device 160 receives input of an excavation instruction signal from the operator, the control device first generates a target trajectory T of the bucket 133. Specifically, the control device 160 generates the target trajectory T in the following procedure.

First, the measurement data acquisition unit 611 acquires measurement data related to the position and the orientation of the revolving body 120, the relative angles of the boom 131, the arm 132, and the bucket 133, the posture of the revolving body 120, and the surface shape of the excavation target. The work implement positioning unit 613 identifies the position of the blade edge of the bucket 133 at the time of the input of the excavation instruction signal based on the measurement data acquired by the measurement data acquisition unit 611. The trajectory generation unit 614 generates the target trajectory T of the bucket 133 such that the target trajectory passes through the position of the blade edge identified by the work implement positioning unit 613 and the excavation amount is equal to the maximum storage capacity of the bucket 133. In addition, at this time, the revolution determination unit 616 records the orientation of the revolving body 120 at the time of the input of the excavation instruction signal in the main memory 630.

FIG. 6 is a flowchart showing an automatic excavation control method according to the first embodiment. When the target trajectory is generated, the control device 160 executes the automatic excavation control shown in FIG. 6.

The measurement data acquisition unit 611 acquires measurement data about the position and orientation of the revolving body 120, the relative angles of the boom 131, the arm 132, and the bucket 133, the posture of the revolving body 120, and the surface shape of the excavation target (step S1). The work implement positioning unit 613 identifies the position of the blade edge of the bucket 133 at the time of the input of the excavation instruction signal based on the measurement data acquired by the measurement data acquisition unit 611 (step S2). The movement control unit 615 determines the target position of the blade edge of the bucket 133 and the target posture of the bucket 133 based on the target trajectory T and the position of the blade edge of the bucket 133 (step S3).

The movement control unit 615 determines the target positions and the target postures of the boom 131 and the arm 132 based on the target position of the blade edge and the target posture of the bucket 133 (step S4). For example, the movement control unit 615 can identify the position of the distal end portion of the boom 131, that is, the position of the base end portion of the arm 132, for moving the blade edge of the bucket 133 to the target position, according to the relationship between the position of the base end portion of the bucket 133 identified from the target position of the blade edge and the target posture of the bucket 133 and the known position of the base end portion of the boom 131. The movement control unit 615 generates an automatic operation signal of the work implement 130 based on the identified target positions and target postures of the boom 131, the arm 132, and the bucket 133 (step S5).

The revolution determination unit 616 calculates the angle (revolution angle) of the difference between the orientation of the revolving body 120 indicated by the measurement data acquired from the position and orientation calculator 151 in step S1 and the orientation of the revolving body 120 at the time of the input of the excavation instruction signal recorded in the main memory 630 (step S6).

The revolution determination unit 616 determines whether the absolute value of the calculated revolution angle exceeds a predetermined revolution angle threshold value (step S7). The revolution angle threshold value may be set in consideration of a measurement error of the position and orientation calculator 151.

When the absolute value of the revolution angle exceeds the revolution angle threshold value (step S7: YES), the revolution determination unit 616 determines that revolution not intended by the operator has occurred.

When it is determined that revolution not intended by the operator has occurred, the brake control unit 617 switches the value of the brake release signal supplied to the brake solenoid valve 1253 to OFF (step S8). Thereafter, the brake control unit 617 maintains the value of the brake release signal to be OFF until the automatic excavation control is ended.

On the other hand, when the absolute value of the revolution angle does not exceed the revolution angle threshold value (step S7: NO), the revolution determination unit 616 determines that revolution not intended by the operator has not occurred. When it is determined that revolution not intended by the operator has not occurred, the brake control unit 617 maintains the value of the brake release signal.

Next, the operation signal output unit 618 outputs the automatic operation signal generated by the movement control unit 615 in step S5 to the control valve 123 (step S9). Accordingly, the work implement 130 moves along the target trajectory T.

The movement control unit 615 determines whether the position of the blade edge of the bucket 133 is positioned at the end point of the target trajectory T (step S10). When the position of the blade edge of the bucket 133 is not positioned at the end point of the target trajectory T (step S10: NO), the control device 160 returns the processing to step S1 and determines the next target position and target posture of the work implement 130. On the other hand, when the blade edge of the bucket 133 is positioned at the end point of the target trajectory T (step S10: YES), the brake control unit 617 sets the value of the brake release signal to ON (step S11). Then, the control device 160 ends the automatic excavation control.

Actions and Effects

As described above, the control device 160 of the work machine 100 according to the first embodiment determines whether the revolving body 120 has revolved during the automatic excavation control, and actuates the revolution parking brake 125 when it is determined that the revolving body 120 has revolved. The automatic excavation control of the work machine 100 is control for driving the work implement 130, without outputting operation signals for the traveling body 110 and a revolving body 120.

Accordingly, the control device 160 can lock the rotation of the revolving body 120 and prevent the revolution of the revolving body 120 not intended by the operator from occurring.

Note that, although the control device 160 according to the first embodiment compares the posture of the revolving body 120 when the automatic excavation control starts, with the posture of the revolving body 120 during the automatic excavation control using the orientation of the revolving body 120 indicated by the measurement data of the position and orientation calculator 151, the present invention is not limited thereto. For example, the control device 160 according to another embodiment may compare the posture of the revolving body 120 when the automatic excavation control starts, with the posture of the revolving body 120 during the automatic excavation control using the integrated value of the angular velocity of the revolving body 120 indicated by the measurement data of the inclination measuring instrument 152 after the start of the automatic excavation control. In addition, the control device 160 according to another embodiment may compare the posture of the revolving body 120 when the automatic excavation control starts, with the posture of the revolving body 120 during the automatic excavation control using an integrated value of measurement values of an encoder, which is not illustrated, provided in the revolving body.

Second Embodiment

The control device 160 according to the first embodiment determines whether the revolving body 120 has revolved by comparing the posture of the revolving body 120 when the automatic excavation control starts, with the posture of the revolving body 120 during the automatic excavation control. In contrast, the control device 160 in a second embodiment determines whether the revolving body 120 has revolved based on the measurement value of the pressure of the hydraulic oil of the revolution motor 124 from the start of the automatic excavation control.

FIG. 7 is a diagram illustrating a configuration of the revolution motor 124 according to the second embodiment.

The revolution motor 124 is connected to the control valve 123. The work machine 100 according to the second embodiment includes pressure gauges 157 that measure the pressure of the hydraulic oil at each of two ports of the revolution motor 124. The revolution direction of the revolution motor 124 is determined by a valve position of the control valve 123. When the control valve 123 is in the neutral position, the hydraulic oil is not supplied to the revolution motor 124. At this time, when the revolution motor 124 rotates due to an action from the outside, the internal pressures of the two ports of the revolution motor 124 change. As a result, the control device 160 can determine whether the revolving body 120 has revolved based on a difference between measurement values of the two pressure gauges 157. Note that, as illustrated in FIG. 7, the hydraulic circuit is provided with a check valve for preventing the internal pressures of the two ports from becoming negative pressure, and a relief valve for preventing an excessive rise in the internal pressures caused by an action from the outside.

The revolution determination unit 616 according to the second embodiment calculates a differential pressure between the ports of the revolution motor 124 based on a difference between the measurement data acquired from the two pressure gauges 157. The revolution determination unit 616 determines that revolution not intended by the operator has occurred when the absolute value of the differential pressure between the ports of the revolution motor 124 exceeds a predetermined differential pressure threshold value. When it is determined that revolution not intended by the operator has occurred, the brake control unit 617 sets the value of the brake release signal to OFF.

Actions and Effects

As described above, the control device 160 of the work machine 100 according to the second embodiment determines whether the revolving body 120 has revolved during the automatic excavation control, and actuates the revolution parking brake 125 when it is determined that the revolving body 120 has revolved. Accordingly, the control device 160 according to the second embodiment can prevent revolution of the revolving body 120 not intended by the operator, similarly to the first embodiment.

Note that, although the control device 160 according to the second embodiment determines whether there is revolution of the revolving body 120 using the differential pressure between the ports of the revolution motor 124, the present invention is not limited thereto. For example, the control device 160 according to another embodiment may measure the flow velocity of the hydraulic oil in the revolution motor 124 and determine whether there is revolution based on the flow velocity. In this case, the control device 160 can identify the direction of the revolution based on the flow direction of the hydraulic oil.

Third Embodiment

The work machine 100 according to the first embodiment and the second embodiment actuates the revolution parking brake 125 when an unintended revolution has occurred. In contrast, the work machine 100 according to a third embodiment actuates the revolution parking brake 125 when the automatic excavation control starts regardless of whether an unintended revolution has occurred. For this reason, the control device 160 according to the third embodiment may not include the revolution determination unit 616.

FIG. 8 is a flowchart showing an automatic excavation control method according to the third embodiment. When a target trajectory T is generated, the control device 160 executes the automatic excavation control shown in FIG. 8. The target trajectory T is generated in the same method as that of the control device 160 according to the first embodiment.

When the automatic excavation control is started, the brake control unit 617 switches the value of the brake release signal supplied to the brake solenoid valve 1253 to OFF (step S21). That is, the brake control unit 617 actuates the revolution parking brake 125 with the input of an excavation instruction signal, that is, an instruction of starting automatic control, as a trigger. Thereafter, the brake control unit 617 maintains the value of the brake release signal to be OFF until the automatic excavation control is ended.

The measurement data acquisition unit 611 acquires measurement data about the position and orientation of the revolving body 120, the relative angles of the boom 131, the arm 132, and the bucket 133, the posture of the revolving body 120, and the surface shape of the excavation target (step S22). The work implement positioning unit 613 identifies the position of the blade edge of the bucket 133 at the time of the input of the excavation instruction signal based on the measurement data acquired by the measurement data acquisition unit 611 (step S23). The movement control unit 615 determines the target position of the blade edge of the bucket 133 and the target posture of the bucket 133 based on the target trajectory T and the position of the blade edge of the bucket 133 (step S24).

The movement control unit 615 determines the target position and the target posture of the boom 131 and the arm 132 based on the target position of the blade edge and the target posture of the bucket 133 (step S25). The movement control unit 615 generates an automatic operation signal of the work implement 130 based on the identified target positions and target postures of the boom 131, the arm 132, and the bucket 133 (step S26). The operation signal output unit 618 outputs the automatic operation signal generated by the movement control unit 615 to the control valve 123 (step S27). Accordingly, the work implement 130 moves along the target trajectory T.

The movement control unit 615 determines whether the blade edge of the bucket 133 is positioned at the end point of the target trajectory T (step S28). When the position of the blade edge of the bucket 133 is not positioned at the end point of the target trajectory T (step S28: NO), the control device 160 returns the processing to step S22 and determines the next target position and target posture of the work implement 130. On the other hand, when the position of the blade edge of the bucket 133 is positioned at the end point of the target trajectory T (step S28: YES), the brake control unit 617 sets the value of the brake release signal to ON (step S29). Then, the control device 160 ends the automatic excavation control.

Actions and Effects

In this way, the control device 160 according to the third embodiment actuates the revolution parking brake 125 and executes the automatic excavation control with the excavation instruction signal as a trigger. For example, the revolution parking brake 125 is actuated following the excavation instruction signal, and the automatic excavation control is executed. As a result, the control device 160 can prevent unintended revolution caused by the work machine 100 from occurring during work.

Other Embodiments

Although embodiments have been described above in detail with reference to the drawings, specific configurations are not limited to those described above, and various design changes and the like can be made. That is, in other embodiments, the order of the processing described above may be changed as appropriate. Furthermore, some processing operations may be executed in parallel.

The control device 160 according to the embodiments described above may be constituted by a single computer, and the configuration of the control device 160 may be arranged to be divided into a plurality of computers, and the plurality of computers may cooperate with each other to serve as the control device 160. In this case, some of the computers constituting the control device 160 may be mounted inside the work machine, and the other computers may be provided outside the work machine.

Although the control device 160 according to the above-described embodiment automatically actuates the revolution parking brake 125 during the automatic excavation control, it is not limited thereto. For example, the control device 160 according to another embodiment may have a function of executing the automatic soil dumping control and may automatically actuate the revolution parking brake 125 during the automatic soil dumping control.

Furthermore, for example, the control device 160 according to another embodiment may determine whether an unintended revolution has occurred in the manual operation by the operator. For example, the control device 160 according to another embodiment may determine whether there is revolution of the revolving body 120 when a manual operation signal for the work implement 130 has been input but a manual operation signal for the revolving body 120 has not been input or when a neutral signal for maintaining the posture of the revolving body 120 has been input. In this case, the control device 160 may release the revolution parking brake 125 with an input of a manual operation signal for the revolving body 120 as a trigger.

Although the revolution motor 124 of the work machine 100 according to the above-described embodiment is a hydraulic motor driven with hydraulic oil as a working medium, it is not limited thereto. For example, the revolution motor 124 according to another embodiment may be an electric motor. A current flowing through the electric motor is an example of a working medium.

Although the work machine 100 according to the embodiments described above is a man-driven vehicle operated by an onboard operator, it is not limited thereto. For example, the work machine 100 according to another embodiment may be a remote-driven vehicle that is actuated following operation signals acquired through communication by a remote operation device operated by an operator in a remote office while viewing the monitoring screen. In that case, some of the functions of the control device 160 may be provided in the remote operation device.

Industrial Applicability

According to the above-described embodiments, the control system for the work machine can prevent unintended revolution caused by the work machine from occurring during work.

Reference Signs List

• • 100 Work machine, 110 Traveling body, 111 Endless track, 112 Travel motor, 120 Revolving body, 121 Engine, 122 Hydraulic pump, 123 Control valve, 124 Revolution motor, 125 Revolution parking brake, 1251 Brake cylinder, 1252 Brake disc, 1253 Brake solenoid valve, 130 Work implement, 131 Boom, 131C Boom cylinder, 132 Arm, 132C Arm cylinder, 133 Bucket, 133C Bucket cylinder, 134 Tilt rotator, 1341 Attachment unit, 1342 Tilt unit, 1343 Rotation unit, 1344 Tilt encoder, 1345 Rotator encoder, 140 Cab, 141 Operator seat, 142 Operation terminal, 143 Operation device, 143LF Left foot pedal, 143LO Left operation lever, 143LT Left travel lever, 143RF Right foot pedal, 143RO Right operation lever, 143RT Right travel lever, 143SW Start switch, 144 Revolution lock switch, 151 Position and orientation calculator, 152 Inclination measuring instrument, 153 Boom stroke sensor, 154 Arm stroke sensor, 155 Bucket stroke sensor, 156 Shape detection device, 157 Pressure gauge, 160 Control device, 610 Processor, 611 Measurement data acquisition unit, 612 Operation signal input unit, 613 Work implement positioning unit, 614 Trajectory generation unit, 615 Movement control unit, 616 Revolution determination unit, 617 Brake control unit, 618 Operation signal output unit, 630 Main memory, 650 Storage, 670 Interface, T Target trajectory