Vehicle rollover avoidance device, work vehicle system, vehicle rollover avoidance method, and vehicle rollover avoidance program

Abstract

To provide an overturn avoidance device or the like that can facilitate work by making a work vehicle stably travel on a slope.SOLUTION: When position information and vehicle angle information of a work vehicle on a slope S are recorded, and a travel path K in one specific lateral movement travel which records the information is set as a first path K1, and a virtual travel path K adjacent to the first path K1 in an inclined direction of the slope S which the work vehicle may enter next to the first path K1 when performing the lateral movement travel is set as a second path K2, a computer comprises: a risk area estimation unit which estimates an area on the second path K2 including an angle decreasing corresponding position Py on the second path K2 adjacent to an angle decreasing position Px on the first path K1 in the inclined direction of the slope S as a risk area RA having a risk that the work vehicle overturns; and a risk information transmission unit which generates and transmits risk information that the work vehicle has approached the risk area RA when the work vehicle approaches the risk area RA on the second path K2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle overturn avoidance device, a work vehicle system, a vehicle overturn avoidance method, and a vehicle overturn avoidance program. [Background technology]

[0002] Conventionally, remote-controlled self-propelled mowers have been used when mowing slopes such as embankments. By using this type of mower, mowing work can be performed by remote control, eliminating the need for workers to mow unstable and dangerous slopes. This not only prevents accidents but also enables labor savings and solves the problem of labor shortages.

[0003] When using the remote-controlled self-propelled mower described above, the operator must perform the mowing work while checking the condition of the ground surface from a position away from the slope. For this reason, if weeds grow on the slope, for example, it is difficult for the operator to grasp the condition of the ground surface, and if the trough-side running parts (tracks and wheels) of the mower enter a depression in the ground surface, the entire mower will tilt significantly toward the valley side, and there is a risk that the mower will tip over or fall down the slope.

[0004] For example, Patent Document 1 describes a system for a work vehicle such as a rice transplanter that stops driving the traveling device when the tilt of the vehicle body reaches or exceeds a predetermined danger angle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-47731 Summary of the Invention [Problem to be solved by the invention]

[0006] However, if the system described in Patent Document 1 detects tilt of the vehicle body and then stops driving the traveling device, it may not always be possible to prevent the vehicle body from tipping over or falling in situations where the vehicle body suddenly tilts due to a sudden change in the ground surface. In particular, if there is a large depression on a steep slope and the traveling device enters this depression, it is expected that the system described in Patent Document 1 will have difficulty responding.

[0007] Therefore, the present invention provides a vehicle overturn avoidance device, a vehicle overturn avoidance method, a vehicle overturn avoidance program, and a work vehicle system equipped with a vehicle overturn avoidance device that allows a work vehicle to travel stably on slopes and facilitate work. [Means for solving the problem]

[0008] A vehicle overturn avoidance device according to one aspect of the present invention is a vehicle overturn avoidance device that has a computer and that avoids overturning of a work vehicle that moves laterally up a slope along contour lines that intersect with the inclination direction of the slope and repeats this movement in the direction of the slope sequentially, the computer comprising a position information acquisition unit that acquires information on the position of the work vehicle on the slope (hereinafter referred to as position information) during the lateral movement of the work vehicle, an angle information acquisition unit that acquires, for each position on the slope during the lateral movement, information on the vehicle inclination angle with respect to a horizontal plane of a width direction virtual line that passes through the center of gravity of the work vehicle and extends in the vehicle width direction (hereinafter referred to as vehicle angle information), an information recording unit that records the position information and the vehicle angle information, and references the recorded position information and the vehicle angle information to calculate the inclination angle of the vehicle relative to a reference inclination angle of the slope on the travel route during the lateral movement (hereinafter referred to as slope reference angle). The system is equipped with an angle reduction position determination unit that determines the position on the slope where both inclination angles are small as an angle reduction position, a risk area estimation unit that, when the travel route in one specific lateral movement travel that recorded the position information and the vehicle angle information is defined as a first route and a virtual travel route that is adjacent to the first route in the inclination direction and that the work vehicle may enter when traveling laterally after the first route, estimates that an area on the second route including a position on the second route that is adjacent to the angle reduction position on the first route in the inclination direction (hereinafter referred to as an angle reduction corresponding position) is a risk area where there is a risk of the work vehicle overturning, and a risk information transmission unit that, when the work vehicle approaches the risk area on the second route, generates and transmits risk information that the work vehicle has approached a risk area.

[0009] In addition, in the above-mentioned vehicle overturn avoidance device, the risk area estimation unit may estimate that the area on the second route including the angle reduction corresponding position corresponding to the angle reduction position when the difference between the slope reference angle and the vehicle inclination angle smaller than the slope reference angle is greater than a predetermined angle reduction threshold is the risk area.

[0010] In addition, in the above-mentioned vehicle overturn avoidance device, the angle reduction threshold may be set so that the value obtained by adding the slope reference angle to the angle reduction threshold is equal to or less than the maximum limit inclination angle, which is the limit value at which the work vehicle can move laterally without overturning.

[0011] In addition, in the above-mentioned vehicle overturn avoidance device, the risk area estimation unit may estimate that an area on the second route including the angle reduction corresponding position is the risk area when the angle reduction positions are continuous along the first route and the continuous distance is greater than a predetermined distance threshold.

[0012] The vehicle overturn avoidance device may further include a control signal transmitting unit that generates and transmits a control signal for controlling the travel of the work vehicle, and the control signal transmitting unit may generate and transmit a signal for reducing the travel speed of the work vehicle when the work vehicle approaches or after it enters the risk area on the second route.

[0013] The vehicle overturn avoidance device may further include a control signal transmitter that generates and transmits a control signal for controlling the travel of the work vehicle, and the control signal transmitter may generate and transmit a signal for stopping the work vehicle when, after the work vehicle has entered the risk area on the second route, the difference between the slope reference angle and the vehicle inclination angle that is greater than the slope reference angle becomes greater than a predetermined angle increase threshold.

[0014] In addition, in the above-mentioned vehicle overturn avoidance device, the angle increment threshold may be set so that the value obtained by adding the slope reference angle to the angle increment threshold is equal to or less than the maximum limit inclination angle, which is the limit value at which the work vehicle can travel without overturning.

[0015] The vehicle overturn avoidance device may further include a control signal transmitter that generates and transmits a control signal for controlling the travel of the work vehicle, and the control signal transmitter may generate and transmit a control signal for causing the work vehicle to travel automatically and along the predetermined travel path of the lateral movement travel.

[0016] Furthermore, in the above-mentioned vehicle overturn avoidance device, the second path may be set so that the distance in the inclination direction between the vehicle width center of the work vehicle traveling laterally along the first path and the vehicle width center of the work vehicle traveling laterally along the second path is 1.5 times or less the width dimension in the vehicle width direction of the traveling device of the work vehicle.

[0017] In addition, in the above-mentioned vehicle overturn avoidance device, the second path may be set so that the lower edge of the contact trajectory of the traveling device with the slope when the work vehicle moves laterally along the second path is positioned below the slope, relative to the higher edge of the contact trajectory of the traveling device with the slope when the work vehicle moves laterally along the first path.

[0018] A work vehicle system according to one aspect of the present invention includes the above-described vehicle rollover avoidance device, a position information detection device that detects the position on the slope and transmits the position information of the detected position to the vehicle rollover avoidance device, a tilt angle detection device that detects the vehicle inclination angle and transmits the vehicle angle information of the detected vehicle inclination angle to the vehicle rollover avoidance device, and a work vehicle equipped with the position information detection device and the tilt angle detection device.

[0019] In the above work vehicle system, the work vehicle may have a traveling device formed by a pair of tracks spaced apart in the vehicle width direction.

[0020] A vehicle overturn avoidance method according to one aspect of the present invention is a vehicle overturn avoidance method that avoids overturning of a work vehicle that moves on a slope along contour lines that intersect with the inclination direction of the slope, and that avoids overturning of the work vehicle by sequentially repeating lateral movement travel on the slope in the inclination direction, the method comprising: a position information acquisition step of acquiring information on the position of the work vehicle on the slope (hereinafter referred to as position information) during the lateral movement travel of the work vehicle; an angle information acquisition step of acquiring, for each position on the slope during the lateral movement travel of the work vehicle, information on the vehicle inclination angle with respect to a horizontal plane of a widthwise virtual line that passes through the center of gravity of the work vehicle and extends in the vehicle width direction (hereinafter referred to as vehicle angle information); an information recording step of recording the position information and the vehicle angle information; and a step of recording the vehicle inclination angle with respect to a reference inclination angle of the slope on the travel route during the lateral movement travel (hereinafter referred to as slope reference angle) by referring to the recorded position information and the vehicle angle information. a risk area estimation step of estimating, when the travel route in one specific lateral movement travel for which the position information and the vehicle angle information are recorded is defined as a first route, and a virtual travel route adjacent to the first route in the inclination direction and which the work vehicle may enter when traveling laterally after the first route, as a second route, an area on the second route including a position on the second route adjacent in the inclination direction to the angle reduction position of the first route (hereinafter referred to as an angle reduction corresponding position) is a risk area where there is a risk of the work vehicle overturning; and a risk information transmission step of generating and transmitting risk information that the work vehicle has approached a risk area on the second route when the work vehicle has approached the risk area.

[0021] A vehicle rollover avoidance program according to one aspect of the present invention is for avoiding rollover of a work vehicle that moves sideways up a slope along contour lines that intersect with the slope in the direction of the inclination of the slope, and that repeats this rollover travel in the direction of the inclination of the slope sequentially. The program includes: a position information acquisition means that acquires information on the position of the work vehicle on the slope (hereinafter referred to as position information) during the sideways travel of the work vehicle; an angle information acquisition means that acquires, for each position on the slope during the sideways travel of the work vehicle, information on the vehicle tilt angle with respect to a horizontal plane of a widthwise virtual line that passes through the center of gravity of the work vehicle and extends in the vehicle width direction (hereinafter referred to as vehicle angle information); an information recording means that records the position information and the vehicle angle information; and a method of recording the vehicle tilt angle by referring to the recorded position information and the vehicle angle information, and and a risk area estimation means for estimating, when the travel route in one specific lateral movement travel that recorded the position information and the vehicle angle information is defined as a first route, and a virtual travel route that is adjacent to the first route in the inclination direction and that the work vehicle may enter when traveling laterally after the first route, that is defined as a second route, an area on the second route that includes a position on the second route that is adjacent to the angle reduction position of the first route in the inclination direction (hereinafter referred to as an angle reduction corresponding position), as a risk area where there is a risk of the work vehicle overturning. and a risk information transmission means for generating and transmitting risk information that the work vehicle has approached a risk area on the second route when the work vehicle approaches the risk area on the second route. [Effects of the Invention]

[0022] The above-described tip-over avoidance device and the like enable the work vehicle to travel stably on slopes, making it possible to carry out work smoothly. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a top view of a work vehicle system according to an embodiment of the present invention. [Figure 2]3 is a diagram showing a travel route when a work vehicle in the work vehicle system travels on a slope. FIG. [Figure 3] FIG. 2 is an enlarged view showing a travel route of a work vehicle in the work vehicle system. [Figure 4] 3 is a block diagram showing a hardware configuration of a vehicle overturn avoidance device in the work vehicle system. FIG. [Figure 5] 3 is a block diagram showing a functional configuration of a vehicle overturn avoidance device in the work vehicle system. FIG. [Figure 6] 10 is a view showing a state in which the work vehicle in the work vehicle system is traveling through a depression on a slope, as viewed from the traveling direction. FIG. [Figure 7] FIG. 10 is a flowchart of a program executed by the vehicle overturn avoidance device in the work vehicle system, showing a method for estimating a risk area. [Figure 8] FIG. 4 is a flowchart of a program executed by the vehicle overturn avoidance device in the work vehicle system, showing a method for avoiding overturn. DETAILED DESCRIPTION OF THE INVENTION

[0024] A work vehicle system 100 according to an embodiment of the present invention will now be described. As shown in FIG. 1, the work vehicle system 100 includes a work vehicle 1, a position information detection device 2, an inclination angle detection device 3, and a warning device 4 mounted on the work vehicle 1, a vehicle rollover avoidance device 5 that prevents the work vehicle 1 from rolling over, and an electronic control unit 6 (ECU: Electronic Control Unit) electrically connected to the vehicle rollover avoidance device 5.

[0025] (Work vehicle) In this embodiment, the work vehicle 1 is a remote-controlled self-propelled brush cutter. The work vehicle 1 is remotely controlled by a worker (operator) located away from the work vehicle 1, and performs brush cutting work while self-propelled. The work vehicle 1 also has a brush cutter 8 located at the front end in the traveling direction, and a traveling device 9 made up of a pair of tracks 9a spaced apart in the vehicle width direction. The work vehicle 1 is not limited to a grass cutter, but may be a vehicle used for grass collection work on a slope S, surveying work, etc.

[0026] As shown in FIG. 2, the work vehicle 1 is operated to sequentially repeat lateral movement travel on a slope S, for example, along contour lines that intersect with the inclination direction of a slope S, such as a slope, from the bottom to the top of the slope S. Specifically, the work vehicle 1 travels on the slope S along a travel route K (first route K1) for a specific lateral movement travel, by remote control operation by the operator, and then makes a U-turn at the end of the first route K1 (for example, a position close to the edge of the slope S), and travels on a lateral movement travel route K (second route K2) adjacent to and above the first route K1. This type of travel is then repeated from the bottom to the top of the slope S, gradually climbing the slope S. Note that at the end of the travel route K for each lateral movement travel, the travel direction may be changed by a switchback rather than a U-turn.

[0027] As shown in Figure 3, in this embodiment, the second path K2 is set so that the lower edge Ky of the contact locus of the valley-side crawler 9a with the slope S when the work vehicle 1 travels on the second path K2 is positioned below the higher edge Kx of the contact locus of the mountain-side crawler 9a with the slope S when the work vehicle 1 travels on the first path K1.

[0028] The same is set for the travel path K of the next lateral movement travel adjacent to and above the second path K2. In other words, when looking at the travel paths K of two lateral movement travels adjacent to each other vertically, the lower edge Ky of the contact path of the travel path of the travel device 9 when the work vehicle 1 travels on the upper travel path K is located below the higher edge Kx of the contact path of the travel device 9 when traveling on the lower travel path K. Therefore, when looking at the travel path 9 from above the slope S, if the work vehicle 1 when traveling on the lower travel path K and the work vehicle 1 when traveling on the upper travel path K were placed side by side in the inclination direction of the slope S, the travel paths K are set so that these work vehicles 1 overlap in the vehicle width direction, and the operator operates the work vehicle 1 along the travel path K that has been set in this way.

[0029] In addition, the travel paths K of two vertically adjacent lateral movement travel paths may be defined as the distance w1 in the inclination direction of the slope S between the vehicle width center of the work vehicle 1 traveling on the upper travel path K and the vehicle width center of the work vehicle 1 traveling on the lower travel path K, which may be at least 1.5 times or less than the width dimension w9 in the vehicle width direction of the traveling device 9, and in the case of this embodiment, w1 is a value that is greater than 0 times w9 and less than 1 time w9. Note that the travel path K set in this manner is a virtual path, and the work vehicle 1 does not necessarily actually travel along the set travel path K. In other words, the set second path K2 indicates a virtual path that the work vehicle 1 may next enter after the work vehicle 1 has actually traveled the first path K1.

[0030] (Location information detection device) Returning to Fig. 1, the position information detection device 2 detects the position of the work vehicle 1 while it is moving laterally on the slope S and transmits a signal of information about the detected position (hereinafter referred to as position information), and is configured, for example, by a GNSS sensor (Global Navigation Satellite System Sensor). The position information detected by the position information detection device 2 includes, for example, latitude and longitude information, but may also include altitude information. Note that the position information detection device 2 is not limited to being configured by a GNSS sensor.

[0031] (Tilt angle detection device) The inclination angle detection device 3 detects the vehicle inclination angle of the work vehicle 1 and transmits a signal of information about the detected vehicle inclination angle (hereinafter referred to as vehicle angle information), and is composed of an acceleration sensor, an inclination sensor, etc. Here, in this embodiment, the vehicle inclination angle indicates the angle of a widthwise virtual line VL that passes through the center of gravity G of the work vehicle 1 and extends in the vehicle width direction with respect to a horizontal plane.

[0032] (warning device) The warning device 4 is configured by, for example, an alarm or a warning light, and uses sound or light to make the operator aware of the approach or intrusion into a risk area RA, which will be described later.

[0033] (Electronic Control Unit (ECU)) The electronic control unit 6 is electrically connected via communication lines to the warning device 4, the vehicle overturn avoidance device 5 (described in detail below), and various other devices and equipment mounted on the work vehicle 1, and electronically controls these devices and equipment. More specifically, the electronic control unit 6 receives signals from the vehicle overturn avoidance device 5 (described in detail below) to operate the warning device 4 and control the operation of the traveling device 9 on the work vehicle 1. In controlling the traveling device 9, the electronic control unit 6 adjusts the traveling speed and direction of the work vehicle 1, and switches the work vehicle 1 between traveling and stopping. There are no particular limitations on the standard of the communication line connected to the electronic control unit 6, and it can be either wired or wireless, but for example, CAN (Controller Area Network) is used. Furthermore, the electronic control unit 6 is not limited to being mounted on the work vehicle 1, and may be located remotely from the work vehicle 1, such as on a server (not shown) or the remote control described above.

[0034] The electronic control unit 6 is also electrically connected to a remote control used by an operator, and it is possible to control the operation of the traveling device 9 via the electronic control unit 6 in response to commands from the remote control. In this case, the electronic control unit 6 is electrically connected to the vehicle overturn avoidance device 5, which will be described in detail later, by, for example, wireless communication.

[0035] (Vehicle rollover prevention device) Next, the vehicle overturn avoidance device 5 will be described. In this embodiment, the vehicle overturn avoidance device 5 is mounted on the work vehicle 1, but the vehicle overturn avoidance device 5 is not limited to being mounted on the work vehicle 1, and may be provided in a location remote from the work vehicle 1, such as a server (not shown) or the remote control described above. In this case, the vehicle overturn avoidance device 5 is electrically connected to the electronic control unit 6, for example, by wireless communication.

[0036] As shown in FIG. 4, the vehicle overturn avoidance device 5 has a computer 500 that communicates with a microcomputer (not shown) in the electronic control unit 6. This computer has a CPU (Central Processing Unit) 501, memory 510 such as ROM (Read Only Memory) or RAM (Random Access Memory), a non-volatile storage device 520 such as an HDD (Hard Disk Drive) or SSD (Solid State Drive), a power supply 530, an input interface 540, an output interface 550, and a bus wiring 560 that connects these. The CPU 501 is a central processing unit that executes a vehicle overturn avoidance program (described later). The memory 510 is used as a work area and storage area for the CPU 501, and the storage device 520 stores the operating system and programs executed by the CPU 501, as well as a data structure used to prevent overturning of the work vehicle 1 (described later). Note that the storage device 520 also stores various other data.

[0037] Next, with reference to Figure 5, the functional configuration realized by the vehicle overturn avoidance program in the vehicle overturn avoidance device 5 will be described. The vehicle overturn avoidance device 5 is a device for preventing overturning of the work vehicle 1 performing work while traveling on a slope S (see Figure 2). That is, the vehicle overturn avoidance device 5 comprises a position information acquisition unit 50, an angle information acquisition unit 51, an information recording unit 52, an angle decrease position determination unit 53, a risk area estimation unit 54, a risk information transmission unit 55, and a control signal transmission unit 56.

[0038] (Location information acquisition unit) The position information acquisition unit 50 acquires position information of the work vehicle 1 on the slope S while the work vehicle 1 is traveling laterally. In other words, the position information acquisition unit 50 receives and acquires position information relating to the position of the work vehicle 1 detected by the position information detection device 2 in real time while the work vehicle 1 is performing a specific lateral movement. In this embodiment, the position information of the work vehicle 1 is acquired each time the work vehicle 1 travels a predetermined distance (for example, ½ or less of the contact length of the crawler 9a of the work vehicle 1) on the travel path K of lateral movement travel. Hereinafter, the positions on the driving history of a specific lateral movement driving route K acquired by the position information acquisition unit 50 (in this embodiment, this driving history is defined as the first route K1) will be represented as P(1), P(2), P(3), ..., P(n-1), P(n), P(n+1), ... in order toward the forward direction of driving (see Figure 2).

[0039] (Angle information acquisition section) The angle information acquisition unit 51 receives and acquires the vehicle angle information detected by the tilt angle detection device 3 in real time for each position on the slope S for which the position information acquisition unit 50 has acquired the position information.

[0040] (Information Recording Section) The information recording unit 52 records the position information acquired by the position information acquiring unit 50 and the vehicle angle information acquired by the angle information acquiring unit 51.

[0041] (Angle reduction position determination section) The angle reduction position determination unit 53 refers to the position information and vehicle angle information recorded in the information recording unit 52, and determines as an angle reduction position Px a position on the slope S where the vehicle inclination angle is partially smaller with respect to a reference inclination angle (hereinafter referred to as a slope reference angle) of the slope S on a specific travel route K (for example, the first route K1 in this embodiment) along which lateral movement travel is being performed, and sets the angle reduction position Px. In this embodiment, the angle reduction positions Px are, for example, three consecutive positions along the first route K1, i.e., each of the three positions P(n-1), P(n), and P(n+1) is an angle reduction position Px (see FIG. 2).

[0042] Hereinafter, as shown in Figure 6, the slope reference angle is defined as α, the vehicle inclination angle measured on the first route K1 is defined as β, and the vehicle inclination angle estimated or measured on the second route K2 is defined as γ. The slope reference angle α may be an initial value measured in advance using drone photography or LiDAR (Light Detection and Ranging) and stored in the angle decrease position determination unit 53. The slope reference angle α may be an average value of vehicle inclination angles acquired on adjacent travel routes K below the travel route K of a specific lateral movement travel being determined by the angle decrease position determination unit 53, or may be calculated in real time based on a moving average of a data group of vehicle inclination angles within a predetermined past range starting from the current position on the travel route K. The method for setting the slope reference angle α is not particularly limited.

[0043] (Risk Area Estimation Unit) 5, the risk area estimation unit 54 estimates that an area on the second route K2 including a position on the second route K2 defined (assumed) above the slope S of the angle decrease position Px of the first route K1, which is an actually measured value (hereinafter referred to as the angle decrease corresponding position Py), is a risk area RA where there is a risk of the work vehicle 1 tipping over. In other words, the risk area RA is at least a part of an area on the virtual travel route K (second route K2) that is adjacent above the slope S to the travel route K (first route K1) on which the angle decrease position Px has been determined and that the work vehicle 1 may enter during its next lateral movement. Note that a position on the second route K2 that corresponds to a position on the first route K1 other than the angle decrease position Px is defined as a non-angle decrease corresponding position Pz, and the second route K2 is defined (assumed) by this non-angle decrease corresponding position Pz and the angle decrease corresponding position Py.

[0044] In this embodiment, when the difference between the slope reference angle α and the vehicle tilt angle β, which is smaller than the slope reference angle α, i.e., α-β, is greater than a predetermined angle decrease threshold θ1, i.e., α-β>θ1, an angle decrease corresponding position Py corresponding to the angle decrease position Px is set.

[0045] Furthermore, in this embodiment, when the maximum limit inclination angle, which is the limit value at which the work vehicle 1 can travel laterally along the contour lines on the slope S without tipping over, is set to θmax, the angle decrease amount threshold θ1 is set so that the value obtained by adding the slope reference angle α to the angle decrease amount threshold θ1 is equal to or less than the maximum limit inclination angle θmax. In other words, θ1 + α ≦ θmax is satisfied. The maximum limit inclination angle θmax depends on the specifications of the work vehicle 1, but is set to 45 degrees, for example.

[0046] Furthermore, in the risk area estimation unit 54 of this embodiment, when the distance d over which the angle reduction positions Px continue is greater than a predetermined distance threshold dt, that is, when the angle reduction corresponding positions Py continue a predetermined number of times (for example, three times in this embodiment) or more, the risk area estimation unit 54 estimates that the area on the second path K2 including the angle reduction corresponding positions Py is a risk area RA.

[0047] (Risk Information Department) When the work vehicle 1 approaches a risk area RA on the virtual second route K2 while traveling laterally above the first route K1, the risk information transmission unit 55 generates and transmits a risk information signal indicating that the work vehicle 1 has approached the risk area RA. The signal transmitted by the risk information transmission unit 55 is received by the warning device 4, which then operates. The risk information transmission unit 55 may transmit risk information, for example, when the work vehicle 1 reaches a position 1 [m] ahead of the risk area RA in the traveling direction during lateral movement travel.

[0048] (Control signal transmitter) The control signal transmitter 56 generates and transmits a signal to reduce the traveling speed of the work vehicle 1 and cause the work vehicle 1 to travel slowly or to stop temporarily when the actual vehicle inclination angle γ of the work vehicle 1 becomes larger than the slope reference angle α when the work vehicle 1 approaches or has entered the risk area RA of the second route K2. The signal generated by the control signal transmitter 56 is received by the electronic control unit 6 and controls the operation of the traveling device 9. Note that the control signal transmitter 56 is not limited to generating a signal when the vehicle inclination angle γ of the work vehicle 1 becomes larger than the slope reference angle α, but may also generate a signal to reduce the traveling speed of the work vehicle 1 and cause the work vehicle 1 to travel slowly or to stop temporarily simply when the work vehicle 1 approaches or has entered the risk area RA while traveling on the second route K2.

[0049] Furthermore, after entering the risk area RA, the control signal transmitter 56 generates and transmits a signal to stop the work vehicle 1 when the difference γ-α between the slope reference angle α and the vehicle inclination angle γ that is greater than the slope reference angle α becomes greater than a predetermined angle increment threshold θ2, i.e., when γ-α>θ2.

[0050] In this embodiment, the angle increment threshold θ2 is set so that the sum of the angle increment threshold θ2 and the slope reference angle α is equal to or less than the above-mentioned maximum limit inclination angle θmax. In other words, θ2+α≦θmax is satisfied.

[0051] (Vehicle rollover prevention program) Next, the flow of the vehicle rollover avoidance program, i.e., the vehicle rollover avoidance method, will be described. In the following, we will assume that the travel route K for determining the angle reduction position Px is the first route K1 and the travel route K where the risk area RA exists is the second route K2, but the flow is executed in the same way for all travel routes K. First, a flow for estimating the risk area RA will be described as shown in Fig. 7. This flow is executed sequentially from position P1 on the first route K1.

[0052] In the flow for estimating the risk area RA, first, a travel distance determination step S0 is executed to determine whether the work vehicle 1 has moved a predetermined distance (for example, 1 / 2 or less of the contact length of the crawler 9a of the work vehicle 1) from the position where data (position information, vehicle angle information) was previously acquired. If the determination in this step S0 is "YES", the process proceeds to position information acquisition step S1, whereas if the determination in step S0 is "NO", the process returns to travel distance determination step S0 again.

[0053] Next, in position information acquisition step S1, position information of the position of the work vehicle 1 on the slope S on the first route K1 is acquired while the work vehicle 1 is moving laterally along the first route K1. Then, angle information acquisition step S2 is executed to acquire vehicle angle information of the work vehicle 1 corresponding to the position for which the position information was acquired. Thereafter, information recording step S3 is executed to record the position information and vehicle angle information.

[0054] Next, the angle decrease position determination step S4 is executed. In this step S4, the information recorded in the information recording step S3 is referenced, and if the vehicle tilt angle β is smaller than the slope reference angle α, the result is "YES." On the other hand, if the vehicle tilt angle β is equal to or greater than the slope reference angle α, the result is "NO." After that, the non-angle decrease corresponding position setting step S10 is executed, in which the position on the second path K2 corresponding to the position determined as "NO" is set as the non-angle decrease corresponding position Pz, and the process returns to the travel distance determination step S0.

[0055] If the determination in the angle decrease position determination step S4 is "YES," the process proceeds to the angle decrease position setting step S5, and the position determined as "YES" in the angle decrease position determination step S4 is set as the angle decrease position Px. Then, after the angle decrease position setting step S5, the angle decrease amount determination step S6 is executed. In this step S6, if the difference α-β between the slope reference angle α and the vehicle inclination angle β is greater than the angle decrease amount threshold θ1, the process determines "YES." On the other hand, if the difference α-β between the slope reference angle α and the vehicle inclination angle β is equal to or less than the angle decrease amount threshold θ1, the process determines "NO." Then, the process executes the non-angle decrease corresponding position setting step S10, which sets the position on the second path K2 corresponding to the angle decrease position Px determined as "NO" as the non-angle decrease corresponding position Pz, and then returns to the movement distance determination step S0.

[0056] If the angle decrease amount determination step S6 returns a "YES" result, an angle decrease corresponding position setting step S7 is executed to set the position on the second path K2 corresponding to the angle decrease position Px determined as "YES" as the angle decrease corresponding position Py, and the process proceeds to angle decrease distance determination step S8. In this step S8, if the distance d over which the angle decrease positions Px continue along the first path K1 is greater than a predetermined distance threshold dt, i.e., if the angle decrease positions Py continue a predetermined number of times or more, the process returns to "YES." Specifically, for example, if three angle decrease corresponding positions Py corresponding to positions P(n), P(n-1), and P(n+1), which are angle decrease positions Px, continue on the second path K2, the process returns to "YES." On the other hand, if the distance d over which the angle decrease positions Px continue is equal to or less than the distance threshold dt, the process returns to movement distance determination step S0.

[0057] If the angle decrease distance determination step S8 returns "YES," i.e., if the vehicle tilt angle β remains smaller than the slope reference angle α for a distance longer than the distance threshold dt, the process proceeds to the risk area estimation step S9, where the area on the second route K2 including the angle decrease corresponding position Py is estimated to be the risk area RA, and it is determined that a "depression D" has formed on the slope S in this area RA (see FIG. 6).

[0058] By executing the flow described above, a data structure indicating the risk area RA and the safety area SA (see FIG. 2) other than the risk area RA is created and stored in the vehicle overturn avoidance device 5.

[0059] Next, a flow for avoiding tipping over of the work vehicle 1 will be described with reference to Figure 8. In this flow, first, a risk area approach determination step S11 is executed to determine whether or not the work vehicle 1 has approached a risk area RA on the second route K2. In this step S11, if the work vehicle 1 has approached the risk area RA, the determination is "YES", and the process proceeds to a warning step S12. In this step S12, a risk information signal indicating that the work vehicle 1 has approached the risk area RA is generated and transmitted by the risk information transmission unit 55, and the electronic control unit 6 that receives the risk information signal operates the warning device 4 to make the operator aware of the danger.

[0060] After warning step S12, angle increase determination step S13 is executed. In step S13, if the vehicle tilt angle γ of the work vehicle 1 becomes larger than the slope reference angle α, a "YES" determination is made, and the process proceeds to speed reduction step S14. In step S14, the control signal transmitter 56 generates a signal to reduce the traveling speed of the work vehicle 1 and cause the work vehicle 1 to move slowly or stop temporarily, and the electronic control unit 6 receives this control signal and controls the traveling device 9 to reduce the traveling speed of the work vehicle 1 and cause the work vehicle 1 to move slowly or stop temporarily. On the other hand, if the vehicle tilt angle γ of the work vehicle 1 becomes equal to or smaller than the slope reference angle α in angle increase determination step S13, a "NO" determination is made, and the process returns to risk area approach determination step S11.

[0061] Then, after speed reduction step S14, angle increment determination step S15 is executed. In step S15, if the difference γ-α between the slope reference angle α and the vehicle inclination angle γ becomes larger than a predetermined angle increment threshold θ2 after the work vehicle 1 approaches or enters the risk area RA on the second route K2, a "YES" determination is made, and the process proceeds to vehicle stop step S16. In step S16, a signal for stopping the work vehicle 1 is generated by the control signal generator 56, and the electronic control unit 6 receives this control signal and controls the traveling device 9 to stop the work vehicle 1. On the other hand, in angle increment determination step S15, if the difference γ-α between the slope reference angle α and the vehicle inclination angle γ becomes equal to or smaller than the predetermined angle increment threshold θ2, a "NO" determination is made, and the process returns to risk area approach determination step S11.

[0062] Returning to the risk area approach determination step S11, if the work vehicle 1 is not approaching the risk area RA, a "NO" determination is made in step S11, and in this case, the out-of-risk area angle increase determination step S21 is first executed. In step S21, if the vehicle tilt angle γ of the work vehicle 1 becomes larger than the slope reference angle α, a "YES" determination is made, and the process proceeds to warning / speed reduction step S22. In step S22, a signal is transmitted from the risk information transmission unit 55 to the warning device 4 of the work vehicle 1, and a signal is transmitted from the control signal transmission unit 56 to the electronic control unit 6, causing the warning device 4 to issue a warning, and the electronic control unit 6 to reduce the speed of the work vehicle 1 and cause the work vehicle 1 to slow down or stop. On the other hand, if a "NO" determination is made in step S21 of determining an increase in the out-of-risk area angle, the process returns to the risk area approach determination step S11.

[0063] After the warning / speed reduction step S22, the out-of-risk-zone increase continuation determination step S23 is executed. In this step S23, it is determined whether the state in which the vehicle inclination angle γ of the work vehicle 1 is larger than the slope reference angle α continues for a predetermined distance (a predetermined number of consecutive positions). Specifically, for example, if the position on the second route K2 for which the determination result in the out-of-risk-zone angle increase determination step S21 is "YES" is defined as position P(m), and the vehicle inclination angle γ of the work vehicle 1 is also larger than the slope reference angle α at the position P(m-1) before that, it is determined that the vehicle inclination angle γ continues to increase, so the determination result is "YES," and the process proceeds to vehicle stop step S24. In this step S24, a signal is transmitted from the control signal transmission unit 56 to the electronic control unit 6, and the electronic control unit 6 stops the work vehicle 1. On the other hand, if the determination result in the out-of-risk-zone increase continuation determination step S23 is "NO," the process returns to the risk-zone approach determination step S11.

[0064] In the step S23 for determining whether or not the angle outside the risk area continues to increase, similar to the step S15 for determining the angle increase amount, if the difference between the slope reference angle α and the vehicle inclination angle γ: γ-α becomes greater than a predetermined angle increase amount threshold θ2, the result may be "YES" and the work vehicle 1 may be stopped.

[0065] (Action and effect) According to the work vehicle system 100 of this embodiment described above, the vehicle overturn avoidance device 5 acquires the position and vehicle tilt angle of the work vehicle 1 in real time while traveling along a specific lateral movement travel route K (first route K1), and can estimate the risk area RA on the travel route K (second route K2) along which the work vehicle 1 is scheduled to travel next. When the work vehicle 1 actually approaches the risk area RA, a warning is issued, allowing the operator to grasp the risk of the work vehicle 1 overturning. Therefore, even if the operator cannot directly visually observe the condition of the ground surface of the slope S, the operator can predict the possibility of the work vehicle 1 overturning, and can slow down or stop the work vehicle 1 and perform work using the work vehicle 1 while checking the behavior of the work vehicle 1. In other words, the work vehicle 1 can be driven stably on the slope S, making it possible to perform work smoothly.

[0066] Here, as shown in Figure 6, if only the upper side of the traveling gear 9 of the work vehicle 1 (1A) traveling laterally on the first route K1 enters the depression D, it is possible that only the lower side of the traveling gear 9 will enter the depression D when the work vehicle 1 (1B) is traveling on the second route K2, which is the next traveling route K after the first route K1. In this case, the vehicle inclination angle β of the work vehicle 1 (1A) traveling on the first route K1 and the slope reference angle α will satisfy β < α, and the vehicle inclination angle β of the work vehicle 1 will be smaller than the inclination angle of the slope S. On the other hand, the vehicle inclination angle γ of the work vehicle 1 (1B) traveling on the second route K2 will satisfy γ > α, and the vehicle inclination angle γ of the work vehicle 1 will be larger than the inclination angle of the slope S. In this way, if the vehicle inclination angle β on the first route K1 is an angle smaller than the slope reference angle α, i.e., a value on the side where the work vehicle 1 is less likely to tip over, then conversely, the vehicle inclination angle γ on the second route K2 will be an angle larger than the slope reference angle α, i.e., a value on the side where the work vehicle 1 is more likely to tip over. In other words, there are cases where the value obtained by adding the slope reference angle α to the difference between the vehicle inclination angle β and the slope reference angle α on the first route K1, i.e., 2α-β, approximately matches the vehicle inclination angle γ on the second route K2, which can increase the risk of tipping over.

[0067] In this regard, in this embodiment, the risk area RA is estimated to be an area on the second route K2 that includes an angle decrease corresponding position Py corresponding to the angle decrease position Px when the relationship between the difference α-β between the slope reference angle α and the vehicle tilt angle β and the angle decrease amount threshold θ1 satisfies α-β>θ1. In particular, in this embodiment, the angle decrease amount threshold θ1 is set so that the vehicle tilt angle γ of the work vehicle 1 does not exceed the maximum limit tilt angle θmax while moving laterally on the second route K2. This makes it possible to more effectively avoid tipping over of the work vehicle 1.

[0068] Furthermore, in this embodiment, if the distance d over which the angle decrease positions Px continue is greater than a predetermined distance threshold dt, the area on the second route K2 that includes the angle decrease corresponding position Py is estimated to be a risk area RA. Therefore, risk is estimated only when a depression D of a predetermined size exists in the lateral movement travel direction of the work vehicle 1, while small depressions D that do not interfere with the travel of the work vehicle 1 can be ignored and work can be continued, improving work efficiency.

[0069] Furthermore, when the work vehicle 1 approaches the risk area RA, risk information that the work vehicle 1 has approached the risk area RA is transmitted, and a warning is issued by the warning device 4. Therefore, the operator can know in advance that there is a possibility that the work vehicle 1 will enter the depression D in the slope S, and can, for example, slow down or stop the work vehicle 1.

[0070] Furthermore, when the work vehicle 1 approaches or has entered the risk area RA, if the vehicle tilt angle γ becomes larger than the slope reference angle α, the travel speed of the work vehicle 1 can be reduced and the work vehicle 1 can be made to travel slowly or temporarily halt. This makes it possible to prevent the work vehicle 1 from entering the depression D and continuing to travel without slowing down, and as a result, it is possible to more effectively prevent the work vehicle 1 from tipping over.

[0071] Furthermore, after the work vehicle 1 has entered the risk area RA, the work vehicle 1 can be stopped when the difference γ-α between the slope reference angle α and the vehicle inclination angle γ becomes larger than the angle increment threshold θ2, and the angle increment threshold θ2 is set so that it does not exceed the maximum limit inclination angle θmax of the work vehicle 1. This makes it possible to more effectively prevent the work vehicle 1 from tipping over.

[0072] However, if the first route K1 and the second route K2 are set at positions separated in the inclination direction of the slope S, even if a risk area RA is estimated on the second route K2 by traveling along the first route K1, when the work vehicle 1 actually travels along the second route K2, if the work vehicle 1 reaches the area estimated as the risk area RA, there is a possibility that a depression D does not actually exist in that area. In other words, there is a possibility that a depression D actually exists below the estimated risk area RA, making the estimation of the risk area RA useless.

[0073] In this regard, in this embodiment, the second path K2 is set so that the lower edge Ky of the contact locus of the valley-side crawler 9a with the slope S when the work vehicle 1 travels on the second path K2 is positioned below the higher edge Kx of the contact locus of the mountain-side crawler 9a of the work vehicle 1 with the slope S when the work vehicle 1 travels on the first path K1, and the travel path K is set so that the work vehicles 1 overlap in the vehicle width direction. For this reason, there is a high possibility that a depression D has actually formed in the area on the second path K2 that is estimated to be the risk area RA, and by estimating the risk area RA, it is possible to avoid the risk of the work vehicle 1 actually entering the depression D and tipping over.

[0074] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. For example, the control signal transmitter 56 in the vehicle overturn avoidance device 5 may generate and transmit a control signal for causing the work vehicle 1 to automatically travel along a predetermined lateral movement travel route K. In other words, the control signal transmitter 56 may acquire position information of the work vehicle 1 and issue an automatic driving command to the electronic control unit 6 to adjust the actual travel position of the work vehicle 1 along a pre-stored travel route K. This prevents the work vehicle 1 from traveling diagonally along the first route K1 in a direction that intersects with the contour lines, i.e., upward or downward in the direction of the inclination of the slope S, during lateral movement travel. This prevents the work vehicle 1 from actually traveling along a route that deviates from the virtual second route K2 in which the risk area RA is set after the first route K1, making the estimation of the risk area RA meaningful and enabling the work vehicle 1 to reliably avoid overturning.

[0075] Furthermore, in the above-described embodiment, a case has been described in which lateral movement travel is repeated from bottom to top in the inclination direction of the slope S, but the work vehicle 1 may also travel conversely, repeating lateral movement travel from top to bottom on the slope S. In this case, the second route K2 is located below the first route K1, and the angle reduction corresponding position Py is located below the slope S with respect to the angle reduction position Px. In this case, it is possible to estimate a risk area RA as a "convex terrain" on the second route K2 by lateral movement travel on the first route K1.

[0076] Furthermore, the traveling device 9 of the work vehicle 1 is not limited to the structure described above, and may be configured with a pair of wheels in the vehicle width direction. [Industrial Applicability]

[0077] According to the tip-over avoidance device and the like of the present invention, it is possible to allow a work vehicle to travel stably on a slope, thereby making work smoother. [Explanation of symbols]

[0078] 1 Work vehicle 2. Location information detection device 3. Tilt angle detection device 4 Warning device 5. Vehicle rollover prevention device 6 Electronic Control Unit 9 Running gear 9a Tracks 50 Location information acquisition section 51 Angle information acquisition section 52 Information Recording Unit 53 Angle reduction position determination section 54 Risk Area Estimation Unit 55 Risk Information Department 56 Control signal transmitter 100 Work Vehicle System 500 calculator G center of gravity K Travel route K1 First Route K2 Alternative pathway Kx high edge Ky Lower Edge Px Angle reduction position Py angle reduction corresponding position RA risk areas S slope VL Width direction virtual line

Claims

1. A vehicle overturn avoidance device that has a computer and that avoids overturning of a work vehicle that moves sideways along a slope along a contour line that intersects with the inclination direction of the slope, and that sequentially repeats this movement in the inclination direction, The computer a position information acquisition unit that acquires information about the position of the work vehicle on the slope (hereinafter, position information) while the work vehicle is traveling laterally; an angle information acquisition unit that acquires information about the vehicle inclination angle with respect to a horizontal plane of a widthwise virtual line that passes through the center of gravity of the work vehicle and extends in the vehicle width direction (hereinafter referred to as vehicle angle information) for each position on the slope during the lateral movement travel; an information recording unit that records the position information and the vehicle angle information; an angle reduction position determination unit that references the recorded position information and the vehicle angle information and determines, as an angle reduction position, the position on the slope where the vehicle tilt angle is smaller than a reference tilt angle (hereinafter referred to as a slope reference angle) of the slope on the travel route where the lateral movement travel is being performed; a risk area estimation unit that estimates, when a first route is defined as the travel route in one specific lateral movement travel that has recorded the position information and the vehicle angle information, and a second route is defined as a virtual travel route that is adjacent to the first route in the inclination direction and that the work vehicle may enter when traveling laterally after the first route, an area on the second route that includes a position on the second route that is adjacent to the angle reduction position of the first route in the inclination direction (hereinafter referred to as an angle reduction corresponding position), as a risk area where there is a risk of the work vehicle overturning; a risk information transmission unit that, when the work vehicle approaches the risk area on the second route, generates and transmits risk information indicating that the work vehicle has approached a risk area; A vehicle rollover avoidance device comprising:

2. The risk region estimation unit 2. A vehicle overturn avoidance device as described in claim 1, wherein an area on the second route including the angle reduction corresponding position corresponding to the angle reduction position when the difference between the slope reference angle and the vehicle inclination angle smaller than the slope reference angle is greater than a predetermined angle reduction threshold is estimated to be the risk area.

3. 3. A vehicle overturn avoidance device according to claim 2, wherein the angle reduction amount threshold is set so that the value obtained by adding the slope reference angle to the angle reduction amount threshold is equal to or less than a maximum limit inclination angle, which is the limit value at which the work vehicle can travel laterally without overturning.

4. The risk region estimation unit 4. A vehicle overturn avoidance device according to claim 1, wherein, when the angle-decreasing positions are continuous along the first route and the continuous distance is greater than a predetermined distance threshold, an area on the second route that includes the angle-decreasing corresponding positions is estimated to be the risk area.

5. a control signal transmitter that generates and transmits a control signal for controlling the travel of the work vehicle; 4. A vehicle overturn avoidance device according to claim 1, wherein the control signal transmitter generates and transmits a signal to reduce the traveling speed of the work vehicle when the work vehicle approaches or enters the risk area on the second route.

6. a control signal transmitter that generates and transmits a control signal for controlling the travel of the work vehicle; 4. A vehicle overturn avoidance device according to claim 1, wherein the control signal transmitter generates and transmits a signal to stop the work vehicle when, after the work vehicle enters the risk area on the second route, the difference between the slope reference angle and the vehicle inclination angle that is greater than the slope reference angle becomes greater than a predetermined angle increase threshold.

7. 7. A vehicle overturn avoidance device according to claim 6, wherein the angle increase threshold is set so that the sum of the angle increase threshold and the slope reference angle is equal to or less than a maximum limit inclination angle, which is the limit value at which the work vehicle can travel without overturning.

8. a control signal generator that generates and emits a control signal for controlling the travel of the work vehicle; 4. The vehicle overturn avoidance device according to claim 1, wherein the control signal transmitter generates and transmits a control signal for causing the work vehicle to travel automatically along the predetermined travel path of the lateral movement travel.

9. 4. A vehicle overturn avoidance device according to claim 1, wherein the second path is set so that the distance in the inclination direction between the vehicle width center of the work vehicle traveling laterally along the first path and the vehicle width center of the work vehicle traveling laterally along the second path is 1.5 times or less the width dimension in the vehicle width direction of a traveling device of the work vehicle.

10. 10. A vehicle overturn avoidance device according to claim 9, wherein the second path is set so that a lower edge of a contact trajectory of the traveling device with the slope when the work vehicle moves laterally along the second path is positioned below the slope, relative to a higher edge of a contact trajectory of the traveling device with the slope when the work vehicle moves laterally along the first path.

11. The vehicle rollover avoidance device according to any one of claims 1 to 3; a position information detection device that detects the position on the slope and transmits the position information of the detected position to the vehicle overturn avoidance device; a tilt angle detection device that detects the vehicle tilt angle and transmits the vehicle angle information of the detected vehicle tilt angle to the vehicle overturn avoidance device; a work vehicle equipped with the position information detection device and the tilt angle detection device; A work vehicle system comprising:

12. 12. The work vehicle system according to claim 11, wherein the work vehicle has a traveling device formed by a pair of tracks spaced apart in the vehicle width direction.

13. A vehicle overturn avoidance method for avoiding overturning of a work vehicle, which avoids overturning by sequentially repeating lateral movement travel on a slope along contour lines that intersect with the inclination direction of the slope, in the inclination direction, the method comprising: a position information acquisition step of acquiring information about the position of the work vehicle on the slope (hereinafter, position information) during the lateral movement of the work vehicle; an angle information acquisition step of acquiring information on a vehicle inclination angle (hereinafter referred to as vehicle angle information) relative to a horizontal plane of a widthwise virtual line that passes through the center of gravity of the work vehicle and extends in a vehicle width direction, for each position on the slope during the lateral movement travel; an information recording step of recording the position information and the vehicle angle information; an angle reduction position determination step of determining, as an angle reduction position, the position on the slope where the vehicle tilt angle is smaller than a reference tilt angle (hereinafter referred to as a slope reference angle) of the slope on the travel route where the lateral movement travel is being performed, by referring to the recorded position information and the vehicle angle information; a risk area estimation step of estimating, when the travel route in one specific lateral movement travel for which the position information and the vehicle angle information are recorded is defined as a first route, and a virtual travel route adjacent to the first route in the inclination direction and which the work vehicle may enter when traveling laterally after the first route, as a second route, an area on the second route including a position on the second route adjacent to the angle reduction position of the first route in the inclination direction (hereinafter referred to as an angle reduction corresponding position) is defined as a risk area where there is a risk of the work vehicle overturning; a risk information transmission step of generating and transmitting risk information indicating that the work vehicle has approached a risk area when the work vehicle has approached the risk area on the second route; A vehicle rollover avoidance method including:

14. In order to prevent a work vehicle from tipping over, the work vehicle moves sideways along a slope along a contour line that intersects with the slope direction, and the movement of the work vehicle is repeated in the slope direction in order to prevent the work vehicle from tipping over. a position information acquisition means for acquiring information on the position of the work vehicle on the slope (hereinafter referred to as position information) while the work vehicle is traveling laterally; angle information acquisition means for acquiring, for each position on the slope during the lateral movement travel, information on the vehicle inclination angle (hereinafter referred to as vehicle angle information) relative to a horizontal plane of a widthwise virtual line extending in the vehicle width direction through the center of gravity of the work vehicle; an information recording means for recording the position information and the vehicle angle information; an angle reduction position determination means for determining, as an angle reduction position, the position on the slope where the vehicle inclination angle is smaller than a reference inclination angle of the slope on the travel route where the lateral movement travel is being performed (hereinafter referred to as a slope reference angle) by referring to the recorded position information and the vehicle angle information; a risk area estimation means for estimating, when a first route is defined as the travel route in one specific lateral movement travel for which the position information and the vehicle angle information are recorded, and a second route is defined as a virtual travel route adjacent to the first route in the inclination direction and which the work vehicle may enter when traveling laterally after the first route, that estimates, as a risk area where there is a risk of the work vehicle overturning, an area on the second route including a position on the second route adjacent to the angle reduction position of the first route in the inclination direction (hereinafter referred to as an angle reduction corresponding position); a risk information transmission means for generating and transmitting risk information indicating that the work vehicle has approached a risk area when the work vehicle has approached the risk area on the second route; A vehicle rollover avoidance program to function as a

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