Work machine control system, work machine, and work machine control method

Abstract

A control system for a work machine comprises a controller. The controller comprises a travel data generation unit that generates travel data indicating travel conditions of the work machine including a target travel route. The travel data generation unit generates travel data so that the steering speed of the work machine does not exceed a first upper limit value when the travel speed of the work machine is equal to or less than a threshold value.

Description

Work machine control system, work machine, and work machine control method

[0001] The present disclosure relates to a work machine control system, a work machine, and a work machine control method.

[0002] In the technical field related to construction machines, there is known a system for searching for a trajectory for an automatic driving vehicle, as disclosed in Patent Document 1. In Patent Document 1, the system searches for a sequence of elements, the position and attitude of the vehicle, which is a path for moving from the initial position of the vehicle to a target position, based on a first constraint condition representing the position of an obstacle, generates a second constraint condition in which a penalty value increases according to the deviation distance from the path, and searches for a sequence of elements, the position, attitude, speed, and steering angle of the vehicle, which is a trajectory for moving from the initial position of the vehicle to the target position, based on the second constraint condition.

[0003] Japanese Patent Application Laid-Open No. 2022-157259

[0004] When the work machine is stationary and steering, the tires of the work machine may wear out.

[0005] An object of the present disclosure is to suppress stationary steering operations of a work machine.

[0006] According to the present disclosure, there is provided a control system for a work machine including a controller. The controller includes a travel data generation unit that generates travel data indicating travel conditions of the work machine including a target travel path, and the travel data generation unit generates the travel data such that the steering speed of the work machine does not exceed a first upper limit when the travel speed of the work machine is equal to or less than a threshold.

[0007] According to the present disclosure, stationary steering operations of a work machine are suppressed.

[0008] FIG. 1 is a diagram that schematically shows a work site management system according to an embodiment. FIG. 2 is a configuration diagram that shows a work machine according to an embodiment. FIG. 3 is a hardware configuration diagram of a controller according to an embodiment. FIG. 4 is a functional block diagram that shows a control system for a work machine according to an embodiment. FIG. 5 is a diagram that explains cyclic work of a work machine according to an embodiment. FIG. 6 is a block diagram that explains a method for generating traveling data according to an embodiment. FIG. 7 is a schematic diagram that explains a method for generating traveling data according to an embodiment. FIG. 8 is a flowchart that shows a method for generating traveling data according to an embodiment. FIG. 9 is a flowchart that shows a method for controlling a work machine according to an embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the embodiments. The components of the embodiments described below can be combined as appropriate. In addition, some components may not be used.

[0010] [Management System] Fig. 1 is a diagram that schematically shows a work site management system 100 according to an embodiment. A work machine 1 operates at a work site. The work machine 1 is an unmanned work machine. An unmanned work machine is a work machine that operates unmanned without being operated by a driver. The work machine 1 is automatically controlled. In this embodiment, the work machine 1 is a wheel loader.

[0011] The management system 100 includes a management server 101. The management server 101 is located outside the work machine 1. The management server 101 includes a computer system. The management server 101 is able to communicate with the work machine 1 via a communication system 102. The communication system 102 includes an internet communication network. Note that the communication system 102 may include a mobile phone communication network, a satellite communication network, or a local area network (LAN).

[0012] [Working Machine] Figure 2 is a configuration diagram showing a working machine 1 according to an embodiment. As shown in Figures 1 and 2, the working machine 1 comprises a body 2, a traveling device 5 including an articulated cylinder 7 and wheels 4, and a working implement 6. The working machine 1 travels around a work site using the traveling device 5. The working machine 1 performs work at the work site using the working implement 6. Examples of work that can be performed by the working machine 1 include excavation work, loading work, and transporting work.

[0013] The vehicle body 2 supports a work implement 6. The vehicle body 2 includes a front vehicle body section 2F and a rear vehicle body section 2R. The front vehicle body section 2F is disposed forward of the rear vehicle body section 2R. The front vehicle body section 2F and the rear vehicle body section 2R are connected via a joint mechanism 3.

[0014] The traveling device 5 supports the vehicle body 2. The traveling device 5 includes wheels 4 and articulate cylinders 7. The wheels 4 are attached to each of the front vehicle body 2F and the rear vehicle body 2R. The wheels 4 include tires. The articulate cylinders 7 connect the front vehicle body 2F and the rear vehicle body 2R. The articulate cylinders 7 are hydraulic cylinders. When the articulate cylinders 7 extend and retract, the front vehicle body 2F bends left and right relative to the rear vehicle body 2R. When the front vehicle body 2F bends relative to the rear vehicle body 2R, the traveling direction of the work machine 1 is adjusted. The articulate cylinders 7 are an example of a steering device for the work machine 1.

[0015] The work implement 6 is supported by the vehicle body 2. The work implement 6 is connected to the vehicle body front portion 2F. The work implement 6 has a boom 8, a bucket 9, a bell crank 10, a bucket link 11, a lift cylinder 12, and a bucket cylinder 13.

[0016] The base end of boom 8 is rotatably connected to the front vehicle body 2F. Bucket 9 is a working member that excavates an excavation target. The base end of bucket 9 is rotatably connected to the tip end of boom 8. The middle portion of bell crank 10 is rotatably connected to bracket 14 of boom 8. The lower end of bell crank 10 is rotatably connected to the base end of bucket link 11. The tip end of bucket link 11 is rotatably connected to bracket 15 of bucket 9. Bell crank 10 is connected to bucket 9 via bucket link 11.

[0017] The boom 8 is operated by a lift cylinder 12. The lift cylinder 12 is a hydraulic cylinder. The base end of the lift cylinder 12 is connected to the front vehicle body 2F. The tip end of the lift cylinder 12 is connected to the boom 8. The bucket 9 is operated by a bucket cylinder 13. The bucket cylinder 13 is a hydraulic cylinder. The base end of the bucket cylinder 13 is connected to the front vehicle body 2F. The tip end of the bucket cylinder 13 is connected to the upper end of the bell crank 10.

[0018] In this embodiment, the work machine 6 is a front-loading type work machine in which the opening of the bucket 9 faces forward during excavation work. The boom 8 is raised or lowered by extending or contracting the lift cylinder 12. The bucket cylinder 13 is extended or contracted by extending or contracting the bucket 9, causing the bucket 9 to tilt or dump.

[0019] 2 , the work machine 1 includes an engine 16, a power take-off (PTO) 17, a power transmission device 18, wheels 4, a brake device 19, a steering pump 20, a steering control valve 21, an articulated cylinder 7, a work implement pump 22, a work implement control valve 23, a lift cylinder 12, a bucket cylinder 13, a position sensor 24, a direction sensor 25, a speed sensor 26, a steering sensor 27, and a controller 28. The traveling device 5 includes the power transmission device 18, the brake device 19, wheels 4, and the articulated cylinder 7.

[0020] The engine 16 is a drive source for the work machine 1. The engine 16 is supported by the vehicle body 2. An example of the engine 16 is a diesel engine. A power take-off 17 distributes the drive force of the engine 16 to a power transmission device 18, a steering pump 20, and a work implement pump 22.

[0021] The power transmission device 18 transmits the driving force of the engine 16 to the wheels 4. The power transmission device 18 controls the traveling speed and direction of travel of the work machine 1. The traveling direction of the work machine 1 includes forward and reverse. The power transmission device 18 may be a transmission having a torque converter, or may be a transmission having a plurality of speed-changing gears. The brake device 19 slows down or stops the working machine 1 while it is traveling.

[0022] The steering pump 20 is a hydraulic pump that is operated by the driving force generated by the engine 16. The hydraulic oil discharged from the steering pump 20 is supplied to the articulate cylinder 7 via a steering control valve 21. The steering control valve 21 controls the flow rate and direction of the hydraulic oil supplied from the steering pump 20 to the articulate cylinder 7. The articulate cylinder 7 is operated by the hydraulic oil from the steering pump 20.

[0023] The work implement pump 22 is a hydraulic pump that is operated by the driving force generated by the engine 16. The hydraulic oil discharged from the work implement pump 22 is supplied to each of the lift cylinder 12 and the bucket cylinder 13 via a work implement control valve 23. The work implement control valve 23 controls the flow rate and direction of the hydraulic oil supplied from the work implement pump 22 to each of the lift cylinder 12 and the bucket cylinder 13. The work implement 6 is operated by the hydraulic oil from the work implement pump 22.

[0024] The position sensor 24 detects the position of the work machine 1. The position of the work machine 1 is detected using a global navigation satellite system (GNSS). The global navigation satellite system includes a global positioning system (GPS). The global navigation satellite system detects the position of a global coordinate system defined by coordinate data of latitude, longitude, and altitude. The global coordinate system is a coordinate system fixed to the Earth. The position sensor 24 includes a GNSS receiver, and detects the absolute position of the work machine 1, which indicates the position of the work machine 1 in the global coordinate system.

[0025] The orientation sensor 25 detects the orientation of the work machine 1. An example of the orientation sensor 25 is an inertial measurement unit (IMU). The orientation sensor 25 may include a calculator that calculates the orientation from position data detected by two GNSS antennas provided on the work machine 1. The calculator can calculate the orientation from a vector connecting the two GNSS antennas.

[0026] The speed sensor 26 detects the traveling speed of the work machine 1. An example of the speed sensor 26 is a magnetic sensor that detects the rotation speed of a drive shaft connected to the wheel 4.

[0027] The steering sensor 27 detects one or both of the steering angle and the steering angular velocity of the work machine 1. An example of the steering sensor 27 is a stroke sensor that detects the stroke length of the articulate cylinder 7.

[0028] FIG. 3 is a hardware configuration diagram of a controller 28 according to an embodiment. The controller 28 includes a computer system. The controller 28 includes a processor 29 such as a CPU (Central Processing Unit), a main memory 30 including a nonvolatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory), a storage 31, and an interface 32 including an input / output circuit. The functions of the controller 28 are stored in the storage 31 as a computer program. The processor 29 reads the computer program from the storage 31, loads it into the main memory 30, and executes processing in accordance with the computer program. The computer program may be distributed to the controller 28 via a network. The management server 101 also includes a computer system such as that shown in FIG. 3.

[0029] 4 is a functional block diagram showing a control system 200 for the work machine 1 according to the embodiment. The control system 200 includes a management server 101 and a controller 28. The detection data of the position sensor 24, the direction sensor 25, the speed sensor 26, and the steering sensor 27 are transmitted to the controller 28. The controller 28 transmits control commands to the traveling device 5 and the work implement 6, respectively.

[0030] 4, the management server 101 has a task data generation unit 33. The controller 28 has a sensor data acquisition unit 34 and an operation control unit 35. The task data generation unit 33, the sensor data acquisition unit 34, and the operation control unit 35 are each realized by the computer system (controller) described above.

[0031] The work data generation unit 33 generates work data indicating the work conditions of the work machine 1. The work conditions include the operating conditions of the traveling device 5 and the operating conditions of the work implement 6. The operating conditions of the traveling device 5 are the traveling conditions of the work machine 1. The work data includes traveling data that indicates the traveling conditions of the work machine 1 and work implement data that indicates the operating conditions of the work implement 6. The work data generation unit 33 includes a traveling data generation unit 331 that generates traveling data that indicates the traveling conditions of the work machine 1, and a work implement data generation unit 332 that generates work implement data that indicates the operating conditions of the work implement 6. The work data generation unit 33 transmits the work data to the work machine 1 via the communication system 102.

[0032] The travel data indicating the travel conditions of the work machine 1 includes a target travel route 36, target position, target orientation, and target travel speed of the work machine 1. In the following description, travel by the work machine 1 based on the travel data will be referred to as work travel as appropriate.

[0033] The components of the travel data of the work machine 1 may be at least one of the target travel route 36, target position, target orientation, and target travel speed of the work machine 1. Based on the work accuracy or work time required of the work machine 1, at least one of the target travel route 36, target position, target orientation, and target travel speed may be appropriately selected as the components of the travel data.

[0034] The sensor data acquisition unit 34 acquires detection data from the position sensor 24, detection data from the orientation sensor 25, detection data from the speed sensor 26, and detection data from the steering sensor 27. The detection data from the position sensor 24 indicates the position of the work machine 1. The detection data from the orientation sensor 25 indicates the orientation of the work machine 1. The detection data from the speed sensor 26 indicates the traveling speed of the work machine 1. The detection data from the steering sensor 27 indicates the steering speed or steering angular velocity of the work machine 1.

[0035] The operation control unit 35 outputs control commands to control each of the traveling device 5 and the work machine 6 based on the work data transmitted from the management server 101. The operation control unit 35 outputs control commands to the traveling device 5 including the articulated cylinder 7 so that the work machine 1 travels based on the traveling data transmitted from the management server 101. The operation control unit 35 outputs control commands to the work machine 6 so that the work machine 6 operates based on the work machine data transmitted from the management server 101.

[0036] [Work Machine Cyclic Work] Figure 5 is a diagram illustrating cyclic work of the work machine 1 according to this embodiment. The work data generation unit 33 generates work data so that the work machine 1 performs cyclic work in which a series of tasks are repeated. A cyclic work is made up of a number of tasks that are interrelated. The cyclic work includes the travel of the work machine 1 and the operation of the work implement 6.

[0037] In this embodiment, the cycle work is made up of a series of six operations, including an empty load forwarding operation M1, an excavating operation M2, a loaded load reverse operation M3, a loaded load forwarding operation M4, a loading operation M5, and an empty load reverse operation M6.

[0038] The sequence of the series of operations is fixed. After the empty load forwarding operation M1 is performed, the digging operation M2 is performed. After the digging operation M2 is performed, the loaded load reversing operation M3 is performed. After the loaded load reversing operation M3 is performed, the loaded load forwarding operation M4 is performed. After the loaded load forwarding operation M4 is performed, the loading operation M5 is performed. After the loading operation M5 is performed, the empty load reversing operation M6 is performed.

[0039] The work machine 1 performs cycle work, which is a series of operations repeated multiple times. After a first empty-load backward movement operation M6 is performed, a second empty-load forward movement operation M1 is performed.

[0040] In cyclical work, the work machine 1 operates based on work data generated by the work data generation unit 33. As described above, the work data includes travel data indicating the travel conditions of the work machine 1 and work implement data indicating the operating conditions of the work implement 6. The travel data includes the target travel path 36, target position, target orientation, and target travel speed of the work machine 1.

[0041] The target travel path 36 is defined in a global coordinate system. The target travel path 36 is defined by a trajectory that passes through a plurality of travel points. The travel points define the target position of the work machine 1. A target heading and a target travel speed for the work machine 1 are set for each of the plurality of travel points. The plurality of travel points are set at intervals. The intervals between the travel points may be uniform or uneven. The target travel path 36 is a virtual line connecting the plurality of travel points. The operation control unit 35 controls the traveling device 5 so that the work machine 1 travels according to the target travel path 36. The operation control unit 35 causes the work machine 1 to travel so that, for example, the center of the rear body 2R of the work machine 1 coincides with the target travel path 36 in the vehicle width direction of the work machine 1.

[0042] The target position refers to the target position of the work machine 1 when it passes through a travel point. The target position of the work machine 1 is defined in a global coordinate system. The target heading of the work machine 1 refers to the target heading of the work machine 1 when it passes through a travel point. The target traveling speed of the work machine 1 refers to the target traveling speed of the work machine 1 when it passes through a travel point.

[0043] The operation control unit 35 controls the traveling device 5 based on the detection data from the position sensor 24 and the detection data from the orientation sensor 25 so that the work machine 1 travels along the target traveling route 36. In other words, the operation control unit 35 controls the traveling device 5 so that the deviation between the detected position of the work machine 1 detected by the position sensor 24 when passing a traveling point and the target position of the work machine 1 set for the traveling point is reduced. The operation control unit 35 also controls the traveling device 5 so that the deviation between the detected orientation of the work machine 1 detected by the orientation sensor 25 when passing a traveling point is reduced and the target orientation of the work machine 1 set for the traveling point is reduced. The operation control unit 35 also controls the traveling device 5 based on the detection data from the speed sensor 26 so that the work machine 1 travels at the target traveling speed. In other words, the operation control unit 35 controls the traveling device 5 so that the deviation between the detected traveling speed of the work machine 1 detected by the speed sensor 26 when passing a traveling point is reduced and the target traveling speed of the work machine 1 set for the traveling point is reduced.

[0044] Empty-load forward movement work M1 is work of moving forward to approach the excavation target. In the embodiment, the excavation target is a mound of natural ground 37 placed on the ground. The mound of natural ground 37 refers to a pile of earth and sand. In empty-load forward movement work M1, the movement control unit 35 moves the work machine 1 forward based on the traveling data so that the work machine 1 approaches the mound of natural ground 37. When moving the work machine 1 forward, the movement control unit 35 controls the attitude of the work machine 6 based on the work machine data so that the mound of natural ground 37 is excavated with the bucket 9. The movement control unit 35 controls the attitude of the work machine 6 so that the cutting edge of the bucket 9 approaches the ground. When the work machine 1 moves forward with the cutting edge of the bucket 9 approaching the ground, the cutting edge of the bucket 9 is inserted into the lower end of the mound of natural ground 37.

[0045] Excavation work M2 is work to excavate an excavation target with the bucket 9 of the work machine 6. The operation control unit 35 tilts the bucket 9 after the cutting edge of the bucket 9 is inserted into the natural ground 37 based on the work machine data. This causes the bucket 9 to excavate the natural ground 37. The bucket 9 scoops up the excavated material. The excavated material is held in the bucket 9.

[0046] The load reversing work M3 is work in which the work machine 6 moves backward so as to move away from the excavation target with the excavated material held in the bucket 9 of the work machine 6. In the load reversing work M3, the operation control unit 35 reverses the work machine 1 so that the work machine 1 moves away from the natural ground 37, based on the traveling data. The operation control unit 35 also controls the attitude of the work machine 6 so that the excavated material does not spill from the bucket 9.

[0047] Load forward operation M4 is an operation in which the work machine 1 moves forward to approach the loading target. In load reverse operation M3, the work machine 1 moves backward toward switchback point 36P defined on the target travel path 36. After switching back at switchback point 36P, the work machine 1 transitions to load forward operation M4. Switchback point 36P refers to the position at which the work machine 1 switches back. Switchback refers to the operation in which the work machine 1, while moving backward, changes direction of travel at an acute angle and moves forward.

[0048] In this embodiment, the loading target is a dump body 39 of a transport vehicle 38 that is capable of traveling on the ground. An example of the transport vehicle 38 is a dump truck. After completing the load reversing operation M3, the work machine 1 moves forward while turning so as to approach the transport vehicle 38. In the load advancing operation M4, the operation control unit 35 moves the work machine 1 forward so as to approach the transport vehicle 38 based on the traveling data.

[0049] The loading operation M5 is an operation of loading the excavated material held in the bucket 9 of the work implement 6 onto a loading target. Based on the work implement data, the operation control unit 35 controls the attitude of the work implement 6 so that the excavated material held in the bucket 9 is loaded into the dump body 39 of the transport vehicle 38. Based on the work implement data, the operation control unit 35 controls the attitude of the work implement 6 so that the excavated material does not spill out of the bucket 9 and so that the bucket 9 is positioned above the upper end of the dump body 39.

[0050] The empty reverse operation M6 is an operation of moving the work machine 1 in reverse so as to move away from the loading target. After the loading operation M5 is completed, the operation control unit 35 moves the work machine 1 in reverse so as to move away from the transport vehicle 38 based on the travel data.

[0051] The work machine 1 repeats a cycle of operations including an empty forward operation M1, an excavation operation M2, a loaded reverse operation M3, a loaded forward operation M4, a loading operation M5, and an empty reverse operation M6 until the excavated material is loaded onto the transport vehicle 38 at the target load amount.

[0052] [Traveling Data Generation Method] Figure 6 is a block diagram illustrating a method for generating travelling data according to the embodiment. In the embodiment, the travelling data generation unit 331 generates travelling data so that the steering speed of the work machine 1 does not exceed a first upper limit when the travelling speed of the work machine 1 is equal to or less than a threshold value. The travelling data generation unit 331 generates travelling data so that the steering speed of the work machine 1 does not exceed a second upper limit that is greater than the first upper limit when the travelling speed of the work machine 1 exceeds the threshold value. The travelling data generation unit 331 generates travelling data so that the articulate cylinder 7, which is the steering device of the work machine 1, does not operate when the travelling speed of the work machine 1 is zero. In the embodiment, the travelling data generation unit 331 generates travelling data for the work machine 1, including the target travel path 36, using a distributed data parallel (DDP) method.

[0053] As shown in FIG. 6 , the traveling data generation unit 331 has a model of the work machine 1. The model of the work machine 1 is a model in which the steering speed does not exceed a first upper limit when the traveling speed of the work machine 1 is equal to or less than a threshold. The threshold for traveling speed is set to an arbitrary value. The first upper limit for steering speed is set to an arbitrary value. As an example, the threshold for traveling speed set in the model is 0 [km / h]. The first upper limit for steering speed set in the model when the traveling speed is equal to or less than 0 [km / h] is 0 [deg / s]. When the traveling speed of the model is equal to or less than 0 [km / h], the steering speed of the model does not exceed 0 [deg / s]. The model is a model in which the articulate cylinder 7 does not operate when the traveling speed is 0 km / h. In other words, the model is a model in which stationary steering does not occur.

[0054] The model of the work machine 1 is a model in which the steering speed does not exceed a second upper limit when the traveling speed of the work machine 1 exceeds a threshold value. The second upper limit is a value greater than the first upper limit. The second upper limit for the steering speed is set to an arbitrary value. As an example, the second upper limit for the steering speed set in the model when the traveling speed is 1 km / h or greater is 20 deg / s. When the traveling speed of the model is 1 km / h or greater, the steering speed of the model does not exceed 20 deg / s. The model is a model in which the articulate cylinder 7 is operable when the traveling speed is 1 km / h or greater.

[0055] The internal state of the model includes element values ​​related to driving. When the target driving path 36 is generated on the xy plane, the element values ​​of the internal state of the model include the following values: [t] in the element value is time.

[0056] ・x[t]: x coordinate indicating the position of the model in the x direction ・y[t]: y coordinate indicating the position of the model in the y direction ・θ[t]: azimuth angle of the model (direction in which the model's body is facing) ・s[t]: steering angle of the model ・u[t]: steering angular velocity of the model ・v[t]: running speed of the model ・a[t]: accelerator operation amount of the model

[0057] The change in the internal state of the model at each time interval dt is expressed by the state transition model equations shown in the following equations (1) to (7).

[0058]

[0059] In equation (3), L is the wheelbase of the model (work machine 1). In equation (5), Lim is the upper limit (first upper limit or second upper limit) of the steering speed at the traveling speed v[t+dt]. In the embodiment, when the traveling speed v[t+dt] is 0 [km / h] or less, the upper limit value Lim is 0 [deg / s], and when the traveling speed v[t+dt] exceeds 1 [km / h], the upper limit value Lim is 20 [deg / s]. In equation (6), F is a function for determining the acceleration force of the model based on the traveling speed v[t] and the accelerator operation amount a[t].

[0060] 7 is a schematic diagram illustrating a method for generating travel data according to an embodiment. As shown in FIG. 7, a target travel path 36 is generated to connect an initial position Pi and a target position Pg. As an example, the initial position Pi is the position where the empty forward movement operation M1 described with reference to FIG. 5 is started, and the target position Pg is the position where the loading operation M5 is performed.

[0061] The traveling data generation unit 331 changes the internal state of the model based on the state transition model equation so that the model travels from the initial position Pi to the target position Pg. The traveling data generation unit 331 sequentially changes the internal state of the model from the initial state of the model in accordance with the input series at the time interval dt to generate the final state of the model. The traveling data generation unit 331 generates traveling data so that the final state of the model becomes the target state of the model. The initial state of the model refers to the internal state of the model at the initial position Pi. The target state of the model refers to the internal state of the model at the target position Pg. The final state of the model refers to the internal state of the model at the final position Pf. Figure 7 shows an example in which the position (x coordinate and y coordinate) of the target state of the model does not match the position (x coordinate and y coordinate) of the final state.

[0062] The input sequence input to the state transition model equation at each time interval dt includes the following control input values: The control input values ​​are values ​​related to the driving operation of the model.

[0063] w [t]: Steering angular acceleration b [t]: Accelerator operation speed

[0064] The steering angular acceleration w[t] is input to equation (5), and the accelerator operation speed b[t] is input to equation (7).

[0065] 8 is a flowchart illustrating a method for generating travel data according to an embodiment. The travel data generation unit 331 determines an initial state and a target state of the model (step SA1). That is, the travel data generation unit 331 determines an initial state element value that indicates the internal state of the model at the initial position Pi and a target state element value that indicates the internal state of the model at the target position Pg.

[0066] The traveling data generation unit 331 determines the initial value of the control input value (step SA2). That is, the traveling data generation unit 331 determines the control input value to be input to the state transition model equation of the initial state.

[0067] The traveling data generation unit 331 inputs the element values ​​of the initial state determined in step SA1 into the state transition model formula (step SA3).

[0068] The travel data generation unit 331 sequentially inputs the control input values ​​to the state transition model formula at each time interval dt to generate the final state of the model (step SA4). The travel data generation unit 331 calculates the element values ​​of the final state that indicate the internal state of the model at the final position Pf.

[0069] The traveling data generation unit 331 evaluates the final state relative to the target state of the model (step SA5). The target state of the model includes the element values ​​of the target state determined in step SA1. The final state of the model includes the element values ​​of the final state calculated in step SA4. As shown in FIG. 6 , the traveling data generation unit 331 inputs the element values ​​of the target state and the element values ​​of the final state into an evaluation function. The element values ​​of the target state and the element values ​​of the final state are input into the evaluation function to calculate an evaluation value.

[0070] The traveling data generation unit 331 determines whether the evaluation value calculated in step SA5 is equal to or less than a predetermined specified value (step SA6).

[0071] In the embodiment, a small evaluation value means that the final state of the model is close to the target state, and a small evaluation value means that the element values ​​of the final state are close to the element values ​​of the target state.

[0072] If it is determined in step SA6 that the evaluation value exceeds the specified value (step SA6: No), the traveling data generation unit 331 returns to the processing of step SA4. If it is determined in step SA6 that the evaluation value is equal to or less than the specified value (step SA6: Yes), the traveling data generation unit 331 ends the processing of generating the traveling data.

[0073] That is, the traveling data generation unit 331 changes the control input values ​​(w[t], b[t]) input to the state transition model equation until the final state of the model approximates the target state. The traveling data generation unit 331 determines, as traveling data, the control input values ​​and the traveling route of the model when the evaluation value becomes equal to or less than a specified value.

[0074] As described above, the model of the work machine 1 is a model in which the steering speed of the model does not exceed the first upper limit when the traveling speed is equal to or less than the threshold, and the steering speed of the model does not exceed the second upper limit when the traveling speed exceeds the threshold. The traveling data generation unit 331 generates traveling data using the model. Therefore, the traveling data generation unit 331 can generate traveling data so that the steering speed of the work machine 1 does not exceed the first upper limit when the traveling speed of the work machine 1 is equal to or less than the threshold, and so that the steering speed of the work machine 1 does not exceed the second upper limit when the traveling speed of the work machine 1 exceeds the threshold. In an embodiment, the traveling data generation unit 331 generates traveling data so that the articulate cylinder 7 does not operate when the traveling speed of the work machine 1 is zero, and can therefore generate traveling data so that the work machine 1 does not perform stationary steering.

[0075] The operation control unit 35 controls the traveling device 5 including the articulate cylinder 7 based on the traveling data generated by the traveling data generation unit 331. The operation control unit 35 controls the traveling device 5 based on the control input values ​​(w[t], b[t]) that make the evaluation value equal to or less than a specified value. The operation control unit 35 controls the traveling device 5 so that the work machine 1 travels along a target traveling route 36 that makes the evaluation value equal to or less than the specified value.

[0076] [Control Method] Figure 9 is a flowchart showing a control method for the work machine 1 according to the embodiment. The travel data generation unit 331 uses a model to generate travel data for the work machine 1 so that the work machine 1 performs cyclic work. The work implement data generation unit 332 generates work implement data for the work implement 6 so that the work machine 1 performs cyclic work. The work data generated by the work data generation unit 33, including the travel data and work implement data, is transmitted to the work machine 1 via the communication system 102. The operation control unit 35 starts cyclic work based on the work data including the travel data and work implement data.

[0077] During cyclical work, the operation control unit 35 causes the work machine 1 to travel for work based on the travel data generated by the travel data generation unit 331. During cyclical work, the operation control unit 35 controls the travel devices 5 including the articulate cylinder 7 based on the travel data generated by the travel data generation unit 331. The operation control unit 35 controls each of the travel devices 5 so that the work machine 1 travels for work according to the target travel path 36.

[0078] For example, at a position where the operation of the work machine 1 is switched, such as switchback point 36P, there is a possibility that the work machine 1 will perform stationary steering. In this embodiment, the travel data is created so that the work machine 1 will not perform stationary steering, and therefore stationary steering of the work machine 1 is suppressed during work travel.

[0079] The operation control unit 35 acquires detection data from the position sensor 24, the direction sensor 25, the speed sensor 26, and the steering sensor 27 (step SB1).

[0080] The operation control unit 35 controls the traveling device 5 based on the detection data of the position sensor 24, the detection data of the direction sensor 25, and the detection data of the speed sensor 26 so as to reduce the deviation between the position of the work machine 1 and the target traveling path 36, and so as to cause the work machine 1 to travel based on the target traveling speed. The operation control unit 35 controls the traveling device 5 based on the control input values ​​(w[t], b[t]) that make the evaluation value equal to or less than a specified value.

[0081] The operation control section 35 determines whether the traveling speed of the work machine 1 is equal to or less than a threshold value based on the detection data of the speed sensor 26 (step SB2).

[0082] If it is determined in step SB2 that the traveling speed of the work machine 1 is equal to or less than the threshold value (step SB2: Yes), the operation control unit 35 controls the articulate cylinder 7 so that the steering speed of the work machine 1 does not exceed the first upper limit. In the embodiment, if the operation control unit 35 determines that the traveling speed of the work machine 1 detected by the speed sensor 26 is zero, it does not operate the articulate cylinder 7 (step SB3).

[0083] Although the travel data is created so that the work machine 1 does not perform stationary steering, there is a possibility that the articulated cylinder 7 will operate when the travel speed of the work machine 1 has decreased due to, for example, the work machine 1 deviating from the target travel path 36. In other words, although the travel data is created so that the work machine 1 does not perform stationary steering, there is a possibility that the work machine 1 will perform stationary steering if a situation arises in which the work machine 1 is unable to travel in accordance with the travel data. In the embodiment, the operation control unit 35 does not operate the articulated cylinder 7 when it is determined that the travel speed of the work machine 1 detected by the speed sensor 26 is zero. Therefore, stationary steering of the work machine 1 is suppressed.

[0084] In step SB2, if it is determined that the traveling speed of the work machine 1 exceeds the threshold value (step SB2: No), the operation control unit 35 controls the articulate cylinder 7 so that the steering speed of the work machine 1 does not exceed the second upper limit value.

[0085] The operation control unit 35 determines whether to end the cycle work (step SB4). If it is determined in step SB4 that the cycle work should be continued (step SB4: No), the operation control unit 35 returns to the processing of step SB1. If it is determined in step SB4 that the cycle work should be continued (step SB4: Yes), the operation control unit 35 ends the cycle work.

[0086] [Effect] As described above, in the embodiment, the control system 200 of the work machine 1 is equipped with a travel data generation unit 331 that generates travel data that indicates the travel conditions of the work machine 1, including the target travel path 36. The travel data generation unit 331 generates travel data such that the steering speed of the work machine 1 does not exceed the first upper limit when the travel speed of the work machine 1 is equal to or less than the threshold value.

[0087] According to this embodiment, the operation of the articulate cylinder 7, which is a steering device, is limited when the travel speed of the work machine 1 is low, thereby suppressing stationary steering operations of the work machine 1. By suppressing stationary steering operations of the work machine 1, the occurrence of inconveniences such as wear on the tires of the work machine 1 and the formation of ruts on the ground at the work site is suppressed.

[0088] Stationary steering operations are likely to be performed at positions where the operation of the work machine 1 is switched, such as switchback point 36P. Switching the operation of the work machine 1 includes at least one of causing a forward moving work machine 1 to move backward, causing a backward moving work machine 1 to move forward, stopping a traveling work machine 1, and causing a stopped work machine 1 to move. In this embodiment, stationary steering operations of the work machine 1 are suppressed even if the traveling data includes a position where the operation of the work machine 1 is switched.

[0089] The control system 200 of the work machine 1 comprises a sensor data acquisition unit 34 that acquires detection data from the speed sensor 26 that detects the traveling speed of the work machine 1, and an operation control unit 35 that controls the articulate cylinder 7, which is the steering device of the work machine 1. When the operation control unit 35 determines that the traveling speed of the work machine 1 is equal to or less than a threshold based on the detection data of the speed sensor 26, it controls the articulate cylinder 7 so that the steering speed of the work machine 1 does not exceed a first upper limit. As a result, even if a situation arises in which the work machine 1 cannot travel in accordance with the traveling data, stationary steering operation of the work machine 1 is suppressed.

[0090] Other Embodiments In the above-described embodiments, the functions of the management server 101 may be provided in the controller 28. For example, the controller 28 may have the functions of the work data generation unit 33. In the above-described embodiments, the management server 101 may be omitted.

[0091] [Supplementary Notes] The present disclosure may also adopt the following configurations. (Supplementary Note 1) A work machine control system comprising a controller, wherein the controller comprises a travel data generation unit that generates travel data indicative of work machine travel conditions including a target travel path, and wherein the travel data generation unit generates the travel data so that the steering speed of the work machine does not exceed a first upper limit when the work machine's travel speed is equal to or less than a threshold. (Supplementary Note 2) The work machine control system described in (Supplementary Note 1), wherein the travel data generation unit generates travel data so that the steering speed of the work machine does not exceed a second upper limit that is greater than the first upper limit when the work machine's travel speed exceeds the threshold. (Supplementary Note 3) The work machine control system described in (Supplementary Note 1) or (Supplementary Note 2), wherein the travel data generation unit generates travel data so that the steering device of the work machine does not operate when the work machine's travel speed is zero. (Supplementary Note 4) A work machine control system according to any one of (Supplementary Note 1) to (Supplementary Note 3), comprising: a sensor data acquisition unit that acquires detection data from a speed sensor that detects the travel speed of the work machine; and an operation control unit that controls a steering device of the work machine, wherein the operation control unit controls the steering device so that the steering speed of the work machine does not exceed a first upper limit value when it is determined that the travel speed of the work machine is equal to or less than a threshold value based on the detection data from the speed sensor. (Supplementary Note 5) A work machine control system according to (Supplementary Note 4), wherein the operation control unit controls the steering device so that the steering speed of the work machine does not exceed a second threshold value that is greater than the first upper limit value when it is determined that the travel speed of the work machine exceeds the threshold value based on the detection data from the speed sensor. (Supplementary Note 6) A work machine control system according to (Supplementary Note 4) or (Supplementary Note 5), wherein the operation control unit does not operate the steering device when it is determined that the travel speed of the work machine detected by the speed sensor is zero.(Supplementary Note 7) A work machine control system according to any one of (Supplementary Note 1) to (Supplementary Note 6), wherein the target travel path is generated so as to connect the initial position and the target position, and the travel data generation unit generates a model of the work machine in which the steering speed does not exceed a first upper limit value when the travel speed is equal to or less than a threshold value, and in which the steering speed does not exceed a second upper limit value that is greater than the first upper limit value when the travel speed exceeds the threshold value, determines an initial state that indicates the internal state of the model at the initial position and a target state that indicates the internal state of the model at the target position, changes the internal state of the model from the initial state in accordance with the input series to generate a final state of the model, and generates travel data so that the final state becomes the target state. (Supplementary Note 8) A work machine comprising the work machine control system according to any one of (Supplementary Note 1) to (Supplementary Note 7). (Supplementary Note 9) A control method for a work machine, comprising: a controller generating driving data indicating driving conditions of the work machine, including a target driving path, so that the steering speed of the work machine does not exceed a first upper limit when the driving speed of the work machine is equal to or lower than a threshold; and causing the work machine to drive based on the driving data.

[0092] 1...working machine, 2...body, 2F...front body, 2R...rear body, 3...joint mechanism, 4...wheel, 5...traveling device, 6...working implement, 7...articulated cylinder, 8...boom, 9...bucket, 10...bell crank, 11...bucket link, 12...lift cylinder, 13...bucket cylinder, 14...bracket, 15...bracket, 16...engine, 17...power take-off, 18...power transmission device, 19...brake device, 20...steering pump, 21...steering control valve, 22...working implement pump, 23...working implement control valve, 24...position sensor, 25...direction sensor, 26...speed sensor, 27...steering sensor, 28... controller, 29...processor, 30...main memory, 31...storage, 32...interface, 33...work data generation unit, 34...sensor data acquisition unit, 35...operation control unit, 36...target driving route, 36P...switchback point, 37...ground, 38...transport vehicle, 39...dump body, 100...management system, 101...management server, 102...communication system, 200...control system, 331...driving data generation unit, 332...work machine data generation unit, M1...empty load forward operation, M2...excavation operation, M3...loaded load backward operation, M4...loaded load forward operation, M5...loading operation, M6...empty load backward operation, Pf...final position, Pi...initial position, Pg...target position.

Claims

1. A work machine control system comprising: a controller; the controller comprising a travel data generation unit that generates travel data indicating travel conditions of the work machine including a target travel path; and the travel data generation unit that generates the travel data such that the steering speed of the work machine does not exceed a first upper limit value when the travel speed of the work machine is equal to or less than a threshold value.

2. A work machine control system as described in claim 1, wherein the travel data generation unit generates the travel data so that when the travel speed of the work machine exceeds a threshold value, the steering speed of the work machine does not exceed a second upper limit value that is greater than a first upper limit value.

3. A work machine control system as set forth in claim 1, wherein the travel data generation unit generates the travel data so that the steering device of the work machine does not operate when the travel speed of the work machine is zero.

4. A work machine control system as described in claim 1, comprising: a sensor data acquisition unit that acquires detection data from a speed sensor that detects the travel speed of the work machine; and an operation control unit that controls the steering device of the work machine, wherein when the operation control unit determines that the travel speed of the work machine is below a threshold based on the detection data from the speed sensor, it controls the steering device so that the steering speed of the work machine does not exceed a first upper limit.

5. A work machine control system as described in claim 4, wherein, when the operation control unit determines that the travel speed of the work machine will exceed a threshold value based on the detection data of the speed sensor, it controls the steering device so that the steering speed of the work machine does not exceed a second threshold value that is greater than a first upper limit value.

6. A work machine control system as set forth in claim 4, wherein the operation control unit does not operate the steering device when it determines that the travel speed of the work machine detected by the speed sensor is zero.

7. A work machine control system as described in claim 1, wherein the target driving path is generated so as to connect an initial position and a target position, and the driving data generation unit generates a model of the work machine in which the steering speed does not exceed a first upper limit when the driving speed is equal to or less than a threshold value, and in which the steering speed does not exceed a second upper limit that is greater than the first upper limit when the driving speed exceeds the threshold value, determines an initial state that indicates the internal state of the model at the initial position and a target state that indicates the internal state of the model at the target position, changes the internal state of the model from the initial state in accordance with an input series to generate a final state of the model, and generates the driving data so that the final state becomes the target state.

8. A work machine comprising the work machine control system according to claim 1.

9. A method for controlling a work machine, comprising: a controller generating driving data indicating driving conditions of the work machine, including a target driving path, so that the steering speed of the work machine does not exceed a first upper limit when the driving speed of the work machine is equal to or lower than a threshold; and causing the work machine to travel based on the driving data.

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