Working machine system, control method, and controller

Abstract

The present invention comprises: a working machine that includes a vehicle body, a working implement attached to the vehicle body, and a traveling device operably attached to the vehicle body; a vehicle speed sensor that measures the vehicle speed based on the operation of the traveling device; a position sensor that is mounted on the working machine, acquires a positioning signal received from a satellite, and determines the position; and a controller that includes a processor. The processor controls, on the basis of the position of the working machine obtained from the positioning signal, the working implement during traveling, and controls the working implement on the basis of the vehicle speed measured by the vehicle speed sensor instead of the position sensor depending on the positioning accuracy of the position sensor.

Description

Work machine system, control method, and controller

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

[0002] Patent Document 1 discloses a control system that causes a work vehicle to efficiently perform work with high finished quality through automatic control. A controller of the control system disclosed in Patent Document 1 acquires current terrain data representing the current terrain of a work site, determines a target depth, acquires positions of a plurality of division points located on the current terrain based on the current terrain data, determines a plurality of reference points obtained by displacing each of the plurality of division points by the target depth in a vertical direction, determines a target designed terrain based on the plurality of reference points, and generates a command signal for operating a work implement according to the target designed terrain.

[0003] Japanese Unexamined Patent Application Publication No. 2019-173371

[0004] Incidentally, a work machine as disclosed in Patent Document 1 can be equipped with a sensor composed of a GNSS (Global Navigation Satellite System) receiver and an antenna (hereinafter simply referred to as a "GNSS sensor") and other sensors. In such a case, the position and the like of the work machine (for example, the position, posture, speed, etc. of the work machine) are specified based on sensor values acquired by each of these sensors. The specified position and the like of the work machine are used as reference data for calculating a work position for automatically controlling the work implement provided in the work machine and a target position of the work implement.

[0005] However, when the position and the like cannot be measured by the GNSS sensor, automatic control of the work machine cannot be continued. In addition, when the positioning accuracy of the position and the like by the GNSS sensor is low, automatic control of the work machine cannot be properly executed, which makes it difficult to continue work.

[0006] The present disclosure has been made in view of the above points, and an object thereof is to provide a work machine system, a control method, and a controller that can increase the application scenarios of automatic control of a work implement included in a work machine even when positioning based on a positioning signal from a satellite is not normal.

[0007] To achieve the above objective, a first aspect of the present disclosure is a work machine system comprising a vehicle body, a work machine attached to the vehicle body, a running device operably attached to the vehicle body, a vehicle speed sensor for measuring the vehicle speed based on the operation of the running device, a position sensor installed on the work machine for acquiring positioning signals received from satellites and determining its position, and a controller including a processor, wherein the processor controls the work machine while it is running based on the position of the work machine determined from the positioning signals, and controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the position sensor, depending on the positioning accuracy of the position sensor.

[0008] Furthermore, in order to achieve the above objective, a second aspect of the present disclosure is a work machine system comprising a vehicle body, a work machine attached to the vehicle body, a running device operably attached to the vehicle body, a vehicle speed sensor for measuring the vehicle speed based on the operation of the running device, a position sensor installed on the work machine for acquiring positioning signals received from satellites and determining its position, and a controller including a processor, wherein the processor controls the work machine to perform a predetermined task based on the position of the work machine determined from the positioning signals, and when a predetermined first condition indicating a decrease in the positioning accuracy of the position sensor is met, the system controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the position sensor, according to the working state of the work machine.

[0009] According to the work machine system, control method, and controller described herein, even when positioning based on satellite positioning signals is not functioning correctly, the application of the automatic control of the work machine equipped in the work machine can be increased.

[0010] This is a schematic diagram of the work machine according to the embodiment. This is a schematic diagram of the work machine system according to the embodiment. This is a block diagram showing the hardware configuration of the controller. This is a diagram for explaining the automated construction of this embodiment. This is a diagram for explaining an environment in which radio waves from satellites are blocked. This is a diagram for explaining mode transitions related to the position estimation of the work machine. This is a flowchart showing the flow of the control process in the first embodiment. This is a flowchart showing the flow of the control process in the second embodiment.

[0011] Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In each drawing, identical or equivalent components and parts are given the same reference numerals. Also, the dimensions and proportions in the drawings are exaggerated for illustrative purposes and may differ from actual proportions.

[0012] <First Embodiment> Figure 1 is a schematic diagram of the work machine 1 according to the first embodiment. The work machine 1 according to this embodiment is a bulldozer. As shown in Figure 1, the work machine 1 comprises a vehicle body 14, a work machine 16, and a travel device 18. In this embodiment, the case where the work machine 1 is a bulldozer is used as an example for explanation, but it is not limited to this. For example, the work machine 1 may be a hydraulic excavator, a wheel loader, or a motor grader, etc.

[0013] The vehicle body 14 has an engine compartment 14A and a driver's cab 14B. The engine compartment 14A is located in front of the driver's cab 14B. A driver's seat (not shown) is located in the driver's cab 14B. The running gear 18 is attached to the lower part of the vehicle body 14. The running gear 18 has a pair of left and right tracks 18B and a pair of left and right sprockets 18A. Note that in Figure 1, only the left track 18B and the left sprocket 18A of the vehicle body 14 are shown. The rotation of the sprocket 18A causes the track 18B to rotate, and the work machine 1 moves.

[0014] The implement 16 is attached to the vehicle body 14. The implement 16 has a lift frame 16A, a blade 16B, and a lift cylinder 16C. The lift frame 16A is attached to the vehicle body 14 so as to be movable up and down. The lift frame 16A supports the blade 16B. The blade 16B included in the implement 16 may be other attachments, and the attachment may be a ripper or the like, which is provided not only at the front of the machine but also at the rear.

[0015] The blade 16B is positioned at the front of the vehicle body 14. The blade 16B moves up and down in conjunction with the vertical movement of the lift frame 16A. The lift frame 16A may be attached to the traveling device 18. The lift cylinder 16C is connected to the vehicle body 14 and the lift frame 16A. The lift frame 16A operates as the lift cylinder 16C extends and retracts.

[0016] Figure 2 is a block diagram showing the configuration of the work machine system 10 according to this embodiment. As shown in Figure 2, the work machine system 10 comprises a work machine 1, a vehicle body 14, a work machine 16, and a traveling device 18.

[0017] The work machine system 10 is equipped with a drive system (not shown) for driving the work machine 1. The drive system (not shown) includes, for example, an engine (not shown), a hydraulic pump (not shown), and a power transmission device (not shown). The hydraulic pump (not shown) is driven by an engine (not shown), which is an example of a prime mover, and discharges hydraulic fluid. The prime mover may be, for example, an electric motor. The hydraulic fluid discharged from the hydraulic pump (not shown) is supplied to each lift cylinder (not shown) via a control valve (not shown). Based on the operation command for the work machine 16, the opening of the control valve (not shown) is adjusted, and the operating speed of each lift cylinder (not shown) is adjusted. The power transmission device (not shown) transmits the driving force of the engine (not shown) to the travel device (not shown). The power transmission device (not shown) may be, for example, an HST (Hydro Static Transmission).

[0018] The power transmission device (not shown) may be, for example, a torque converter or a transmission having multiple gears. Alternatively, the power transmission device (not shown) may be, for example, a diesel-electric system. The driving force of the work implement 16 may be electric rather than hydraulic.

[0019] As shown in Figure 2, the control system 12 that can be mounted on the vehicle body 14 includes an operating device 20A, an input device 20B, a GNSS sensor 22 which is an example of a position sensor, an IMU 24, a vehicle speed sensor 26, a blade tip position detection sensor 28, and a controller 30.

[0020] The operating device 20A and the input device 20B are located in the driver's cab 14B. The operating device 20A is a device for operating the work implement 16 and the travel device 18. The operating device 20A is located in the driver's cab 14B. The operating device 20A receives operations from the operator to drive the work implement 16 and the travel device 18 and outputs an operation signal corresponding to the operation. The operating device 20A includes, for example, an operating lever, pedal, and switch. The operating device 20A and the input device 20B do not necessarily have to be located in the driver's cab 14B. If the operating device 20A and the input device 20B are not located in the driver's cab 14B, the work implement 16 and the travel device 18 are controlled by remote control or autonomous control.

[0021] The input device 20B is a device for setting the automatic control of the work machine 1, which will be described later. The input device 20B receives operations from the operator and outputs operation signals corresponding to the operations. The operation signals from the input device 20B are output to the controller 30. The input device 20B includes, for example, a touch panel display. However, the input device 20B is not limited to a touch panel and may also include hardware keys. For example, the touch panel display may show information about the work site based on the location information of the work machine 1, information about the terrain of the construction target at the work site, information about the height relationship of the blade between the work machine 1 and the construction target, and information about the current control mode of the work machine 1.

[0022] The GNSS sensor 22 is composed of, for example, a GPS (Global Positioning System) receiver (not shown), a main first GNSS antenna 22A, and a sub second GNSS antenna 22B. As shown in Figure 1, for example, the first GNSS antenna 22A and the second GNSS antenna 22B are arranged on the driver's cab 14B. The receiver (not shown) of the GNSS sensor 22 receives positioning signals from satellites, calculates the position and speed of the first GNSS antenna 22A based on the positioning signals, acquires position and speed data of the vehicle body 14, and acquires azimuth data of the vehicle body 14 based on the positioning signals of the first GNSS antenna 22A and the second GNSS antenna 22B.

[0023] The controller 30, described later, acquires position data, speed data, and orientation data of the vehicle body 14 obtained by the GNSS sensor 22. The controller 30 also acquires roll angle, pitch angle, and yaw angle, which represent the attitude of the vehicle body 14, based on the position data, speed data, and orientation data of the vehicle body 14.

[0024] The IMU 24 acquires the acceleration and angular velocity of the vehicle body 14 of the work machine 1. Based on the acceleration and angular velocity of the vehicle body 14 acquired by the IMU 24, the controller 30 acquires the roll angle, pitch angle, and yaw angle, which represent the attitude of the vehicle body 14. The IMU 24 is an example of an attitude sensor.

[0025] The vehicle speed sensor 26 acquires the vehicle speed of the vehicle body 14. Specifically, the vehicle speed sensor 26 is a sensor that detects the rotational speed of the sprocket 18A. Therefore, the vehicle speed of the vehicle body 14 corresponding to the rotational speed of the track 18B in accordance with the rotation of the sprocket 18A is acquired. The vehicle speed sensor 26 is installed inside the left and right sprockets 18A. In this embodiment, the speed obtained from the average of the rotational speeds of the left and right tracks 18B is used as the vehicle speed of the vehicle body 14.

[0026] The blade tip position detection sensor 28 is a sensor for detecting the position of the blade tip of the blade 16B. For example, the blade tip position detection sensor 28 is installed on the lift cylinder 16C and detects the position of the blade tip of the blade 16B by detecting the degree of extension and retraction of the lift cylinder 16C. Alternatively, the blade tip position detection sensor 28 is a sensor that detects the position of the blade tip of the blade 16B based on sensor values ​​acquired by an IMU installed on the blade 16B. Alternatively, the blade tip position detection sensor 28 may be a sensor that detects the position of the blade tip of the blade 16B based on sensor values ​​acquired by an optical sensor (e.g., a Lidar) provided on the work machine 1.

[0027] The controller 30 is programmed to control the work machine 1 based on the acquired data. The controller 30 includes a processor, such as a CPU (Central Processing Unit), as will be described later. The controller 30 acquires operation signals from the operating device 20A and the input device 20B. Note that the controller 30 is not limited to a single unit, but may be divided into multiple controllers. If the controller 30 is divided into multiple controllers, some of its functions may be distributed and located outside the driver's cab 14B. The controller 30 moves the vehicle body 14 by controlling the running device 18 or the power transmission device (not shown). The controller 30 moves the blade 16B up and down by controlling the control valve (not shown).

[0028] Figure 3 is a block diagram showing the hardware configuration of the controller 30. As shown in Figure 3, the controller 30 includes a CPU (Central Processing Unit) 101, a memory 102, a storage device 103, an input / output interface (I / F) 104, a storage medium reader 105, and a communication interface 106. Each component is connected to the others via a bus 107 so that they can communicate with each other.

[0029] The storage device 103 stores a control program for executing control processing, which will be described later. The CPU 101 is a central processing unit that executes various programs and controls each component. Specifically, the CPU 101 reads a program from the storage device 103 and executes the program using memory 102 as a workspace. The CPU 101 controls each component and performs various calculations according to the program stored in the storage device 103.

[0030] Memory 102 is composed of RAM (Random Access Memory) and temporarily stores programs and data as a working area. Storage device 103 is composed of ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), etc., and stores various programs including the operating system and various data.

[0031] The input / output interface 104 is an interface for inputting and outputting data to and from external devices. In this embodiment, the following external devices are connected to the controller 30 via the input / output interface 104: the operating device 20A, the input device 20B, the GNSS sensor 22, the IMU 24, the vehicle speed sensor 26, and the blade tip position detection sensor 28.

[0032] The storage medium reader 105 reads data stored on various storage media such as CD (Compact Disc)-ROM, DVD (Digital Versatile Disc)-ROM, Blu-ray disc, and USB (Universal Serial Bus) memory, and writes data to the storage media.

[0033] The communication interface 106 is an interface for communicating with other devices, and standards such as Ethernet®, FDDI, or Wi-Fi® can be used. The above-mentioned external devices may also be connected to the controller 30 via the communication interface 106.

[0034] The controller 30 automatically controls the work machine 1 based on current terrain data representing the current terrain of the construction site, target design terrain data representing the target terrain of the construction site, and blade tip position data representing the position of the blade tip of the blade 16B. The automatic control of the work machine 1 may be semi-automatic control performed in conjunction with manual operation by an operator. Alternatively, the automatic control of the work machine 1 may be fully automatic control performed without manual operation by an operator. The movement of the work machine 1 may be automatically controlled by the controller 30. For example, the movement control of the work machine 1 may be fully automatic control performed without manual operation by an operator. Alternatively, the movement control may be semi-automatic control performed in conjunction with manual operation by an operator. Alternatively, the movement of the work machine 1 may be performed by manual operation by an operator.

[0035] Furthermore, the controller 30 calculates the position, speed, and attitude of the vehicle body 14 of the work machine 1 using a known Kalman filter and a known inertial navigation calculation. The calculated position, speed, and attitude of the vehicle body 14 are used to control the work machine 1. When the automatic construction mode is set, the controller 30 performs various controls.

[0036] [1. Automatic Construction by Work Machine 1] Figure 4 is a diagram illustrating the automatic construction of this embodiment. As shown in Figure 4, for example, the controller 30 controls the cutting edge of the blade 16B of the work machine 1a to make contact with the design surface T. The controller 30 then controls the work machine 1b to perform excavation and leveling work. For example, if the load on the blade 16B of the work machine 1c in Figure 4 increases, the controller performs control such as controlling the position of the blade 16B. This ensures that stable automatic excavation and leveling continue, as shown by the work machine 1d in Figure 4. As shown in Figure 4, in order to construct the existing terrain into a terrain like the design surface T, the existing terrain is repeatedly constructed into a smooth surface N as shown in Figure 4, until it approaches the final design surface T.

[0037] Furthermore, when performing automated construction as shown in Figure 4, it is necessary to accurately estimate the position of the work machine 1. However, in environments where radio waves from satellites are blocked, the accuracy of the position estimation of the work machine 1 obtained by the GNSS sensor 22 deteriorates, which may make it difficult to continue automated construction.

[0038] Figure 5 illustrates an environment in which radio waves from a satellite are blocked. As shown in Figure 5, consider a case where the work machine 1 performs automatic construction based on its position acquired by the GNSS sensor 22. In such a case, if the positioning signal from satellite St is blocked by an obstruction SH as shown in Figure 5, the accuracy of estimating the position and attitude of the work machine 1 deteriorates. Furthermore, even if the positioning signal from satellite St is not completely blocked, the reception of the positioning signal may deteriorate if the work machine 1 is traveling near a building or tree. In this case as well, the accuracy of estimating the position and attitude of the work machine 1 deteriorates. Then, as shown in Figure 5, when the positioning signal from satellite St becomes receivable, or when the reception of the positioning signal recovers to a good state, the work machine 1 performs automatic construction based on its position acquired by the GNSS sensor 22.

[0039] [2. Discarding GNSS Data] In this embodiment, if the data acquired by the GNSS sensor 22 (hereinafter also referred to as "GNSS data") deteriorates, the GNSS data is discarded. The GNSS data includes the position data, speed data, and direction data of the vehicle body 14. The direction data included in the GNSS data is data indicating the direction relative to the global reference, obtained from the relationship between the position of the main first GNSS antenna 22A and the position of the sub second GNSS antenna 22B.

[0040] For example, the controller 30 determines the positioning accuracy of the GNSS sensor 22 based on the difference between a change in position data included in GNSS data and a position change obtained from time integration of velocity data included in the GNSS data. When the positioning accuracy is good, the difference between the amount of change in the position data and the amount of position change obtained from the time integration of the velocity data is small, and when the accuracy deteriorates, the difference becomes large. This determination method takes into consideration that velocity data included in GNSS data is less susceptible to deterioration in the reception status of positioning signals from satellites than position data included in GNSS data. The controller 30 discards the GNSS data when the difference in position change is equal to or greater than a predetermined threshold value.

[0041] Further, the controller 30 may determine the positioning accuracy of the GNSS sensor 22 based on an index related to the variance of positions measured by the GNSS sensor 22 during operation of the working implement 16. In the present embodiment, the operation of the working implement 16 refers to, for example, a state where a bulldozer levels the ground with a blade 16B while traveling straight. When the angular velocity of the work machine 1 is equal to or higher than a predetermined value, such as when the bulldozer is turning, the determination of positioning accuracy using the positioning result of the GNSS sensor 22 cannot be performed with high accuracy. Therefore, in the determination of positioning accuracy, the condition that the working implement 16 is in operation is required.

[0042] For example, the controller 30 calculates the altitude of the GNSS antenna 22A obtained by comprehensively calculating each piece of data acquired by the IMU 24, the GNSS sensor 22, and the vehicle speed sensor 26 (hereinafter also referred to as "controller-calculated altitude") and the altitude of the GNSS antenna 22A obtained from position data included in the GNSS data (hereinafter also referred to as "GNSS-measured altitude"), and determines whether or not the GNSS data is deteriorated based on the difference between the two altitudes. The altitude of the GNSS antenna 22A is the on-site coordinate system O Ｇ represents the position coordinate in the Z direction in

[0043] For example, the controller 30 calculates the difference between the controller-calculated altitude and the GNSS-measured altitude at each time within a predetermined time interval, determines that the GNSS data is deteriorated and discards the GNSS data when the variance of the differences is larger than a predetermined threshold value.

[0044] Furthermore, Hotelling's theory may be applied to the determination based on the indicator relating to position dispersion. Specifically, the controller 30 calculates an outlier a(x) shown in the following formula (1) using Hotelling's theory, and rejects the GNSS data when the outlier a(x) exceeds the specified level of the chi-square distribution. In formula (1), x is observed data, which is the difference between the altitude calculated by the controller and the altitude measured by GNSS. μ is the moving average value of the observed data x, and σ is the moving variance value of the observed data x.

[0045]

[0046] [3. Mode Relating to Position Estimation of Work Machine 1] In the present embodiment, as modes relating to position estimation of the work machine 1, there are a GNSS mode in which position estimation is performed using GNSS data, and a vehicle speed mode in which position estimation is performed using the vehicle speed detected by a vehicle speed sensor 26. When the controller 30 starts control of the work machine 1, it estimates the position of the work machine 1 in the GNSS mode, and executes automatic control of the work implement 16 and the like. Furthermore, as described above, when the controller 30 determines to reject the GNSS data, it shifts to the vehicle speed mode, estimates the position of the work machine 1 in the vehicle speed mode, and continues automatic control of the work implement 16 and the like.

[0047] In position estimation of the work machine 1 in the vehicle speed mode, the controller 30 inputs, for example, the vehicle speed detected by the vehicle speed sensor 26 and each piece of data acquired by the IMU 24 into a mathematical model such as a Kalman filter to estimate the position of the work machine 1.

[0048] Furthermore, when the controller 30 estimates the position of the work machine 1 in the vehicle speed mode, if the positioning accuracy of the GNSS data is recovered, that is, if the GNSS data no longer satisfies the rejection condition, the controller 30 returns the position estimation mode from the vehicle speed mode to the GNSS mode.

[0049] Furthermore, as a mode for position estimation, an initial mode may be provided that uses initial parameters and is used when control of the work machine 1 starts. In addition, a mode may be provided for the case when GNSS data is discarded and the vehicle speed detected by the vehicle speed sensor 26 cannot be used. An example of this case is described in detail below.

[0050] Figure 6 is a diagram illustrating the mode transitions related to position estimation of the work machine 1 in this embodiment. As shown in Figure 6, in this embodiment, the position of the work machine 1 during automated construction is estimated by switching between initialization mode M0, GNSS_FIX mode M1-1, GNSS_NON-FIX mode M1-2, and vehicle speed mode M2.

[0051] Initialization mode M0 is the mode set when the work machine 1 starts driving. GNSS_FIX mode M1-1 is a mode in which GNSS data can be acquired by the GNSS sensor 22, and the GNSS data is highly accurate. GNSS_NON-FIX mode M1-2 is a mode in which GNSS data can be acquired by the GNSS sensor 22, but the GNSS data is less accurate than the GNSS data acquired in GNSS_FIX mode M1-1, or does not output a valid position. Vehicle speed mode M2 ​​is a mode in which the position of the vehicle body 14 is estimated based on the vehicle speed of the vehicle body 14 acquired by the vehicle speed sensor 26, and the acceleration and angular velocity of the vehicle body 14 acquired by the IMU 24.

[0052] As shown in Figure 6, for example, when the mode of the work machine 1 is in initialization mode M0, if the initialization process after the work machine 1 starts driving is completed, the mode of the work machine 1 transitions from initialization mode M0 to GNSS_FIX mode M1-1. Also, as shown in Figure 6, for example, when the mode of the work machine 1 is in GNSS_FIX mode M1-1, if an instruction signal is issued indicating that the estimation of the position of the work machine 1 has ended, the mode of the work machine 1 transitions from GNSS_FIX mode M1-1 to initialization mode M0.

[0053] Furthermore, as shown in Figure 6, for example, when the mode of the work machine 1 is GNSS_FIX mode M1-1, if the valid conditions for the vehicle speed mode are met and the invalid conditions for GNSS data are met, the mode of the work machine 1 transitions from GNSS_FIX mode M1-1 to vehicle speed mode M2. Also, as shown in Figure 6, for example, when the mode of the work machine 1 is GNSS_FIX mode M1-1, if the valid conditions for the vehicle speed mode are not met and the invalid conditions for GNSS data are met, the mode of the work machine 1 transitions from GNSS_FIX mode M1-1 to GNSS_NON-FIX mode M1-2.

[0054] Furthermore, as shown in Figure 6, for example, when the mode of the work machine 1 is in vehicle speed mode M2, if the conditions related to GNSS data are met, the mode of the work machine 1 transitions from vehicle speed mode M2 ​​to GNSS_FIX mode M1-1. Also, as shown in Figure 6, for example, when the mode of the work machine 1 is in vehicle speed mode M0, if the conditions related to the vehicle speed mode are no longer met, the mode of the work machine 1 transitions from vehicle speed mode M2 ​​to GNSS_NON-FIX mode M1-2. Also, as shown in Figure 6, for example, when the mode of the work machine 1 is in vehicle speed mode M2, if an instruction signal is issued to terminate the estimation of the position and attitude of the work machine 1, the mode of the work machine 1 transitions from vehicle speed mode M2 ​​to initialization mode M0.

[0055] Furthermore, as shown in Figure 6, for example, when the mode of the work machine 1 is GNSS_NON-FIX mode M1-2, if the conditions related to GNSS data are met, the mode of the work machine 1 transitions from GNSS_NON-FIX mode M1-2 to GNSS_FIX mode M1-1. Also, as shown in Figure 6, for example, when the mode of the work machine 1 is GNSS_NON-FIX mode M1-2, if an instruction signal is issued to terminate the estimation of the position and orientation of the work machine 1, the mode of the work machine 1 transitions from GNSS_NON-FIX mode M1-2 to initialization mode M0.

[0056] For example, if the vehicle speed mode conditions representing conditions 1 to 3 below are met, and the specific conditions set for each other mode are also met, the mode of the work machine 1 will transition from the other mode to vehicle speed mode M2.

[0057] 1. The detected value obtained by the IMU 24 and the detected value obtained by the vehicle speed sensor 25 are consistent. 2. The work is low-load work (for example, the rotation of the work machine 1 is less than a predetermined value). 3. The driving conditions are appropriate.

[0058] The vehicle speed mode M2 ​​includes a first vehicle speed mode and a second vehicle speed mode. The first vehicle speed mode is a temporary mode that immediately transitions to the GNSS_FIX mode when the degradation of the GNSS data is restored. For example, if the surrounding environment of the location where the work machine 1 is located is under a bridge or under a highway, the degradation of the GNSS data is temporary. Therefore, anticipating the degradation of the GNSS data in such an environment, in the first vehicle speed mode, when the degradation of the GNSS data is restored, it immediately transitions to the GNSS_FIX mode.

[0059] On the other hand, the second vehicle speed mode is a vehicle mode that continues the vehicle speed mode even if the degradation of GNSS data recovers. For example, if the surrounding environment of the location where the work machine 1 is located is near a wall or a tree, the degradation of GNSS data will continue. In such an environment, even if the degradation of GNSS data recovers, there is a possibility that the GNSS data will degrade again. Therefore, anticipating the degradation of GNSS data in such an environment, the second vehicle speed mode is a mode that continues the vehicle speed mode without immediately transitioning to GNSS_FIX mode even if the degradation of GNSS data recovers.

[0060] The mode to which the vehicle speed mode transitions from another mode to either the first or second vehicle speed mode is set, for example, by the operator of the work machine 1. Alternatively, the mode to which the vehicle speed mode transitions from another mode to either the first or second vehicle speed mode is determined based on the degree of degradation of the GNSS data. For example, as described above, if the variance of the difference between the altitude of the GNSS antenna 22A calculated from each data acquired by the IMU 24 and the altitude of the GNSS antenna 22A obtained from the position data included in the GNSS data is greater than the first threshold, the mode of the work machine 1 transitions to the first vehicle speed mode. On the other hand, for example, if the variance of the difference is greater than a predetermined second threshold, the mode of the work machine 1 transitions to the second vehicle speed mode. The first threshold is greater than the second threshold.

[0061] Next, the operation of the work machine system 10 according to the first embodiment will be described. When the start of automatic construction by the work machine 1 is instructed, the control processing routine shown in Figure 7 is executed. Note that the control processing shown in Figure 7 is an example of the control method of this disclosure.

[0062] In step S10, the CPU 101 of the controller 30 sets the position estimation mode of the work machine 1 to GNSS mode. Next, in step S12, the CPU 101 acquires data from the GNSS sensor 22, IMU 24, vehicle speed sensor 26, and cutting edge position detection sensor 28.

[0063] Next, in step S14, the CPU 101 determines whether the currently set position estimation mode is GNSS mode or not. If it is GNSS mode, the process proceeds to step S16; if it is vehicle speed mode, the process proceeds to step S20.

[0064] In step S16, the CPU 101 determines whether the positioning accuracy of the GNSS data meets predetermined conditions and whether to discard the GNSS data. If the GNSS data is to be discarded, the process proceeds to step S18; otherwise, the GNSS mode is maintained and the process proceeds to step S24. In step S18, the CPU 101 sets the position estimation mode of the work machine 1 to the vehicle speed mode and proceeds to step S24.

[0065] In step S20, the CPU 101 determines whether the positioning accuracy of the GNSS data has recovered, that is, whether the conditions for rejecting the GNSS data are no longer met. If the positioning accuracy of the GNSS data has recovered, the process proceeds to step S22; otherwise, the process maintains the vehicle speed mode and proceeds to step S24. In step S22, the CPU 101 sets the position estimation mode of the work machine 1 to GNSS mode and proceeds to step S24.

[0066] In step S24, the CPU 101 estimates the position of the work machine 1 in the set mode. Next, in step S26, the CPU 101 controls the automatic construction by the work machine 16 based on the estimated position of the work machine 1.

[0067] Next, in step S28, the CPU 101 determines whether or not the automatic construction has been instructed to end. If the automatic construction has not been instructed to end, the process returns to step S12. If it has been instructed to end, the control process ends.

[0068] As described above, the work machine system according to the first embodiment includes a vehicle body, a work machine attached to the vehicle body, a travel device operably attached to the vehicle body, a vehicle speed sensor for measuring the vehicle speed based on the operation of the travel device, a GNSS sensor installed on the work machine, and a controller including a CPU, which is an example of a processor. The CPU controls the work machine while driving based on the position of the work machine obtained from the positioning signal acquired by the GNSS sensor, and controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the GNSS sensor, depending on the positioning accuracy of the GNSS sensor. This makes it possible to continue automatic control of the work machine while driving even if the positioning signal from the satellite is not normal.

[0069] Furthermore, when position estimation is performed based on data detected by the IMU, as mentioned above, errors accumulate over time. In this embodiment, the vehicle speed sensor is a sensor that measures the vehicle speed based on the operation of the running gear, such as a sensor that detects the rotational speed of a sprocket provided on the running gear, and by using the vehicle speed detected by the vehicle speed sensor for position estimation, the position of the work machine can be estimated with high accuracy even when GNSS data is rejected.

[0070] <Second Embodiment> Next, a second embodiment will be described. In the second embodiment, parts common to the first embodiment will be denoted by the same reference numerals and their descriptions will be omitted.

[0071] [1. Rejection of GNSS Data] In this embodiment, if the GNSS rejection conditions indicating a decrease in the positioning accuracy of the GNSS data are met, the GNSS data is rejected. The GNSS rejection conditions are an example of the "first condition" of this disclosure.

[0072] [2. Modes for Position Estimation of Work Machine 1] In the second embodiment, as in the first embodiment, there are two modes for position estimation of the work machine 1: a GNSS mode that uses GNSS data to estimate the position, and a vehicle speed mode that uses the vehicle speed detected by the vehicle speed sensor 26 to estimate the position. In the vehicle speed mode, the vehicle speed measured from the rotational speed of the sprocket 18A, measured by the vehicle speed sensor 26, is used. In this case, the accuracy of the vehicle speed measurement varies depending on the working state of the work machine 1. For example, when the work machine 1 is traveling on flat ground, the speed can be measured with high accuracy. On the other hand, when the work machine 1 is traveling on uneven ground, turning, or excavating, the accuracy of the vehicle speed measurement deteriorates due to the effects of slippage of the tracks 18B, etc. In this case, the accuracy of the position estimation of the work machine 1, which is estimated using the vehicle speed, also deteriorates.

[0073] Therefore, a vehicle speed mode condition is defined for transitioning to the vehicle speed mode when the accuracy of position estimation using vehicle speed does not deteriorate. The controller 30 then transitions the position estimation mode to the vehicle speed mode when the GNSS data is rejected and the vehicle speed mode condition is met. The vehicle speed mode condition is an example of the "second condition" in this disclosure.

[0074] The following conditions may be set as vehicle speed mode conditions: 1. The detected value obtained by the IMU 24 and the detected value obtained by the vehicle speed sensor 25 are consistent. 2. The work is low-load work (for example, the rotation of the work machine 1 is less than a predetermined value). 3. The driving conditions are appropriate.

[0075] Conditions 2 and 3 above may be conditions for specifying that the work performed by the work machine 1 is leveling the ground. For example, a more specific condition may be that the average slewing angular velocity of the work machine 1 is a first set value TH related to the slewing angular velocity. Ｒ，１ The traction force generated in the work machine 1 is less than the set value TH for traction force. Ｔ The difference between the cutting edge position of the blade 16B detected by the cutting edge position detection sensor 28 and the design surface is less than the set value TH. ＰConditions such as the value being less than a certain value may be imposed. Additionally, a condition may be imposed that the operator of machine 1 has selected a setting that allows the transition to vehicle speed mode.

[0076] Furthermore, when the controller 30 is estimating the position of the work machine 1 in vehicle speed mode, if the positioning accuracy of the GNSS data is restored, that is, if the GNSS data no longer meets the GNSS rejection conditions, the controller 30 will switch the position estimation mode back from vehicle speed mode to GNSS mode.

[0077] Furthermore, an initial mode may be provided for position estimation, using initial parameters, to be used when control of the work machine 1 begins. Additionally, a mode may be provided for cases where GNSS data is rejected and the vehicle speed mode conditions are not met. This mode may be, for example, an IMU mode that estimates the position of the work machine 1 based on the acceleration and angular velocity of the vehicle body 14 acquired by the IMU 24.

[0078] Next, the operation of the work machine system 10 according to the second embodiment will be described. When the start of automatic construction by the work machine 1 is instructed, the control processing routine shown in Figure 8 is executed. Note that the control processing shown in Figure 8 is an example of the control method of this disclosure.

[0079] In step S10, the CPU 101 of the controller 30 sets the position estimation mode of the work machine 1 to GNSS mode. Next, in step S12, the CPU 101 acquires data from the GNSS sensor 22, IMU 24, vehicle speed sensor 26, and cutting edge position detection sensor 28.

[0080] Next, in step S14, the CPU 101 determines whether the currently set position estimation mode is GNSS mode or not. If it is GNSS mode, the process proceeds to step S16; if it is vehicle speed mode or IMU mode, the process proceeds to step S24.

[0081] In step S16, the CPU 101 determines whether or not to reject the GNSS data based on the GNSS rejection conditions. If the GNSS data is to be rejected, the process proceeds to step S18; otherwise, the GNSS mode is maintained and the process proceeds to step S28.

[0082] In step S18, the CPU 101 determines whether the vehicle speed mode conditions are met based on the data acquired in step S12. If the vehicle speed mode conditions are met, the process proceeds to step S20; otherwise, the process proceeds to step S22.

[0083] In step S20, the CPU 101 sets the position estimation mode of the work machine 1 to the vehicle speed mode and proceeds to step S28. On the other hand, in step S22, the CPU 101 sets the position estimation mode of the work machine 1 to the IMU mode and proceeds to step S28.

[0084] In step S24, the CPU 101 determines whether the positioning accuracy of the GNSS data has recovered, that is, whether the GNSS data no longer meets the GNSS rejection conditions. If the positioning accuracy of the GNSS data has recovered, the process proceeds to step S26; otherwise, it returns to step S18. In step S26, the CPU 101 sets the position estimation mode of the work machine 1 to GNSS mode and proceeds to step S28.

[0085] In step S28, the CPU 101 estimates the position of the work machine 1 in the set mode. Next, in step S30, the CPU 101 controls the automatic construction by the work machine 16 based on the estimated position of the work machine 1.

[0086] Next, in step S32, the CPU 101 determines whether or not an instruction has been given to terminate the automatic construction. If an instruction has not been given to terminate the automatic construction, the process returns to step S12. If an instruction has been given to terminate the process, the control process ends.

[0087] As described above, the work machine system according to the second embodiment includes a vehicle body, a work machine attached to the vehicle body, a running device operably attached to the vehicle body, a vehicle speed sensor for measuring the vehicle speed based on the operation of the running device, a GNSS sensor installed on the work machine, and a controller including a CPU, which is an example of a processor. The CPU controls the work machine to perform a predetermined task based on the position of the work machine obtained from the positioning signal acquired by the GNSS sensor, and when the GNSS rejection condition indicating a decrease in the positioning accuracy of the GNSS sensor is met, the CPU controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the GNSS sensor, according to the working state of the work machine. This increases the number of situations in which the automatic control of the work machine provided by the work machine can be applied, even when positioning based on positioning signals from satellites is not normal.

[0088] This disclosure is not limited to the embodiments and examples described above, and various modifications and applications are possible without departing from the gist of this disclosure.

[0089] For example, the program processing flow described in the above embodiment is just one example, and unnecessary steps may be deleted, new steps added, or the processing order rearranged, as long as it does not deviate from the main purpose.

[0090] Furthermore, although the above embodiment was described using the example of a case where the controller 30 is mounted on the vehicle body 14, it is not limited to this. For example, the controller 30 may not be mounted on the vehicle body 14, and the vehicle body 14 may be controlled based on signals output from a controller 30 located at a different location from the vehicle body 14.

[0091] Furthermore, the control processing that the CPU reads and executes in the above embodiment may be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, and dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processing, such as ASICs (Application Specific Integrated Circuits). The control processing may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0092] Furthermore, although the above embodiment describes a configuration in which the program that executes the control processing is pre-stored (installed) in a storage device, the invention is not limited to this configuration. The program may be provided in the form of a recording medium such as a CD-ROM, DVD-ROM (Digital Versatile Disc Read Only Memory), or USB (Universal Serial Bus) memory. Alternatively, the program may be provided in the form of a download from an external device via a network.

[0093] 1. Working machine 10. Working machine system 12. Control system 14. Vehicle body 16. Working machine 18. Traveling device 22. GNSS sensor 26. Vehicle speed sensor 30. Controller 101. CPU 103. Memory device

Claims

1. A work machine system comprising: a vehicle body; a work machine attached to the vehicle body; a travel device operably attached to the vehicle body; a vehicle speed sensor for measuring the vehicle speed based on the operation of the travel device; a position sensor installed on the work machine for acquiring positioning signals received from satellites and determining its position; and a controller including a processor, wherein the processor controls the work machine while traveling based on the position of the work machine determined from the positioning signals, and controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the position sensor, depending on the positioning accuracy of the position sensor.

2. The work machine system according to claim 1, wherein the positioning accuracy of the position sensor is determined based on the difference between the change in position data measured by the position sensor and the change in position obtained from the time integral of the velocity data measured by the position sensor.

3. The work machine system according to claim 1, wherein the positioning accuracy of the position sensor is determined based on an index relating to the dispersion of positions measured by the position sensor during the operation of the work machine.

4. The work machine system according to any one of claims 1 to 3, wherein the processor, when controlling the work machine based on the vehicle speed measured by the vehicle speed sensor, determines whether or not to resume control of the work machine based on the position determined by the positioning signal, according to the positioning accuracy of the position sensor.

5. A work machine system comprising: a vehicle body; a work machine attached to the vehicle body; a running device operably attached to the vehicle body; a vehicle speed sensor for measuring the vehicle speed based on the operation of the running device; a position sensor installed on the work machine for acquiring positioning signals received from satellites and determining its position; and a controller including a processor, wherein the processor controls the work machine to perform a predetermined task based on the position of the work machine determined from the positioning signals; and, when a predetermined first condition indicating a decrease in the positioning accuracy of the position sensor is met, controls the work machine based on the vehicle speed measured by the vehicle speed sensor instead of the position sensor, according to the working state of the work machine.

6. The work machine system according to claim 5, wherein when a predetermined second condition indicating that the work machine is in good working condition is met, the work machine is controlled based on the vehicle speed measured by the vehicle speed sensor.

7. The work machine system according to claim 6, wherein the second condition is that the turning angular velocity of the vehicle body is less than a predetermined value.

8. The work machine system according to claim 6 or 7, wherein the work machine is mounted in front of the vehicle body, the control for performing the predetermined work includes controlling the position of the work machine and the movement of the vehicle body by the travel device, and the second condition is that the traction force generated in the work machine is less than a predetermined value.

9. The work machine system according to claim 6 or 7, wherein the work machine is mounted in front of the vehicle body, the control for performing the predetermined work includes controlling the position of the work machine and the movement of the vehicle body by the travel device, and the second condition is that the difference between the position of the work machine and a preset target position is less than a predetermined value.

10. The work machine system according to claim 6 or claim 7, wherein the second condition is that the work machine is moving forward.

11. The work machine system according to claim 1 or claim 5, wherein the controller is mounted on the vehicle body.

12. The work machine system according to claim 1 or claim 5, wherein the vehicle speed sensor is a sensor that detects the rotational speed of a sprocket provided on the running device.

13. A control method for a work machine including a vehicle body, a work machine attached to the vehicle body, and a traveling device operably attached to the vehicle body, wherein a processor controls the work machine while traveling based on the position of the work machine obtained from a position sensor installed on the work machine which obtains a position signal received from a satellite and determines its position, and controls the work machine based on the vehicle speed measured by a vehicle speed sensor which measures the vehicle speed based on the operation of the traveling device, in accordance with the positioning accuracy of the position sensor.

14. The control method according to claim 13, wherein the positioning accuracy of the position sensor is determined based on the difference between the change in position data measured by the position sensor and the change in position obtained from the time integral of the velocity data measured by the position sensor.

15. The control method according to claim 13, wherein the positioning accuracy of the position sensor is determined based on an index relating to the dispersion of positions measured by the position sensor during the operation of the work machine.

16. The control method according to any one of claims 13 to 15, wherein, when the processor is controlling the work machine based on the vehicle speed measured by the vehicle speed sensor, the processor determines whether or not to resume control of the work machine based on the position determined by the positioning signal, according to the positioning accuracy of the position sensor.

17. A control method for a work machine including a vehicle body, a work machine attached to the vehicle body, and a traveling device operably attached to the vehicle body, wherein a processor controls the work machine to perform a predetermined task based on the position of the work machine obtained from a positioning signal received by a position sensor installed on the work machine and which determines the position by acquiring positioning signals received from satellites, and when a predetermined first condition indicating a decrease in the positioning accuracy of the position sensor is met, the control method controls the work machine based on the vehicle speed measured by a vehicle speed sensor that measures the vehicle speed based on the operation of the traveling device, instead of the position sensor, according to the working state of the work machine.

18. The control method according to claim 17, wherein when a predetermined second condition indicating that the working condition of the work machine is good is met, the work machine is controlled based on the vehicle speed measured by the vehicle speed sensor.

19. A controller for a work machine, comprising a vehicle body, a work machine attached to the vehicle body, and a traveling device operably attached to the vehicle body, wherein the controller controls the work machine while traveling based on the position of the work machine obtained from a position sensor installed on the work machine which obtains position signals received from a satellite and determines its position, and controls the work machine based on the vehicle speed measured by a vehicle speed sensor which measures the vehicle speed based on the operation of the traveling device, in accordance with the positioning accuracy of the position sensor.

20. A controller for a work machine, comprising a vehicle body, a work machine attached to the vehicle body, and a traveling device operably attached to the vehicle body, wherein the controller controls the work machine to perform a predetermined task based on the position of the work machine obtained from a position sensor installed on the work machine, which obtains position signals received from a satellite and determines the position of the work machine, and when a predetermined first condition indicating a decrease in the position accuracy of the position sensor is met, the controller controls the work machine based on the vehicle speed measured by a vehicle speed sensor that measures the vehicle speed based on the operation of the traveling device, in place of the position sensor, according to the working state of the work machine.

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