Control device for work machine

Abstract

Provided is a control device for a work machine such as a wheel loader provided with an articulated steering mechanism, the control device making it possible for the work machine to stably travel even on a slope having a gradient. Provided is a control device for a work machine that plans a target route, which is a movement route to a target position, and autonomously travels following the planned target route, wherein the control device comprises a route planning unit 120 that plans the target route on the basis of the current position of the work machine and the target position, and the route planning unit 120 corrects the target route on the basis of gradient information pertaining to a road surface on the target route.

Description

Work machine control device

[0001] The present invention relates to a control device for a work machine.

[0002] Conventionally, work machines that automatically travel to a predetermined position have been proposed. Patent Document 1 discloses an automatic travel technology for a wheel loader, in which, when the positions and vehicle body orientation for each operation of excavation, loading, and turning are set, a travel path is generated based on that information, and the vehicle body is controlled to follow the generated travel path.

[0003] In general, the driving route generated by such an automatic driving control device is selected from multiple route candidates that can reach a specified position and vehicle direction, using parameters such as driving distance and distance to obstacles, etc. In this way, an efficient route with a short driving distance can be selected while avoiding contact with obstacles.

[0004] Japanese Patent Application Publication No. 10-212035

[0005] According to Patent Document 1, the positions and vehicle orientations of excavation, loading, and turning back on the generated travel route are determined by using the positions and vehicle orientations of the vehicle when it was manually driven in advance as teaching data. Furthermore, the travel route connecting the excavation, loading, and turning back positions is realized by configuring it using a predetermined function. Specifically, a method is disclosed in which curved roads are drawn as circular arcs or clothoid curves. This allows for an efficient route with excellent route tracking and a short travel distance.

[0006] On the other hand, because a wheel loader is a work machine equipped with an articulated steering mechanism that allows the vehicle body itself to bend, the bending angle of the vehicle body constantly changes while traveling, and as a result, the position of the center of gravity of the vehicle body constantly changes. Therefore, if the vehicle travels along a travel path generated without taking into account the bending angle of the vehicle body and changes in the position of the center of gravity, the vehicle body may tilt significantly, resulting in unstable behavior.

[0007] In particular, when driving on a slope, the effects of changes in the vehicle's bending angle and center of gravity become apparent, so in order to ensure stable autonomous driving, it is necessary to plan a route that matches the gradient conditions of the road surface on which the vehicle will be driven.

[0008] There is also technology that constantly monitors the tilt and center of gravity of the vehicle body while traveling, and regenerates (reschedules) the travel path or stops the vehicle if the tilt of the vehicle body becomes too great and its behavior becomes unstable. However, in a work machine equipped with an articulated steering mechanism, in which the center of gravity of the vehicle body is likely to change due to changes in the bending angle of the vehicle body and the state of the load loaded in the bucket, which is a work tool, regeneration (rescheduling) of the travel path may change the bending angle of the vehicle body or the state of the load, resulting in a change in the center of gravity of the vehicle body, making the vehicle's behavior even more unstable, or the vehicle body's stopping control may cause the vehicle to stop frequently, resulting in reduced work efficiency. Therefore, as mentioned above, in order to perform stable autonomous traveling, it is necessary to plan in advance a path that is less likely to change the bending angle and center of gravity of the vehicle body (less likely to tilt) in accordance with the gradient conditions of the road surface on which the vehicle is traveling.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a control device for a work machine, such as a wheel loader equipped with an articulated steering mechanism, that allows the work machine to travel stably even on slopes with inclines.

[0010] In order to achieve the above-mentioned object, the control device for a work machine according to the present invention is a control device for a work machine that plans a target route, which is a movement route to a target position, and automatically travels by following the planned target route, and the control device is characterized in that it includes a route planning unit that plans the target route based on the current position of the work machine and the target position, and the route planning unit modifies the target route based on gradient information of the road surface on the target route.

[0011] According to the present invention, it is possible to prevent the behavior of the vehicle body from becoming unstable when traveling on a route that includes a slope. Note that problems, configurations, and effects other than those described above will become clear from the description of the following embodiments.

[0012] FIG. 1 is an external view of a work machine according to an embodiment of the present invention. FIG. 2 is a control system diagram of a work machine according to an embodiment of the present invention. FIG. 3 is a functional block diagram of an automatic driving control device according to an embodiment of the present invention. FIG. 4 is a flowchart showing calculation processing performed by a behavior management unit according to an embodiment of the present invention. FIG. 5 is a flowchart showing calculation processing performed by a route planning unit according to an embodiment of the present invention. FIG. 6 is a conceptual diagram showing the relationship between a road surface gradient vector and a target route. An example of a route plan using a road surface gradient vector. An example of a route plan using the heights (difference in elevation) of left and right traveling bodies. An example of transition of the heights (difference in elevation) of left and right traveling bodies when traveling on a route.

[0013] Hereinafter, a wheel loader will be described as an example of a work machine according to an embodiment of the present invention with reference to the drawings. In each drawing, the same reference numerals will be used to designate the same components, and duplicate descriptions will be omitted where appropriate.

[0014] An embodiment of the present invention will be described with reference to FIGS.

[0015] FIG. 1 is a diagram that schematically shows the appearance of a wheel loader according to this embodiment, and FIG. 2 is a diagram that schematically shows a control system for the wheel loader according to this embodiment.

[0016] 1 , the wheel loader V1 is provided with a bucket 1, which is a working implement, at the front of the vehicle body, and a lift arm 2 that rotatably supports the bucket 1. The lift arm 2 is rotatably supported by the wheel loader V1, and the bucket 1 moves up and down as the lift arm 2 rotates. The lift arm 2 also rotatably supports a bell crank 3, and when the bell crank 3 rotates, the bucket 1 also rotates relative to the lift arm 2 via a bucket link 4.

[0017] The wheel loader V1 is equipped with a front right tire 21FR, a front left tire 21FL, a rear right tire 21RR ( FIG. 2 ), and a rear left tire 21RL, and travels by driving these tires. The wheel loader V1 is also equipped with an articulated type (also called a center-bending type) steering mechanism, and turns by bending the front part of the vehicle body relative to the rear part of the vehicle body around an axis perpendicular to the vehicle body, thereby generating an angle difference between the front and rear parts of the vehicle body.

[0018] 2, the control system includes an engine 10 as a power source, and the engine 10 drives a hydraulic pump 14 and a driving force transmission device 22. The driving force transmission device 22 transmits the driving force of the engine 10 to the front right tire 21FR and the front left tire 21FL, and the rear right tire 21RR and the rear left tire 21RL via a center joint 23C and a front differential device 24F and a rear differential device 24R, respectively, causing the wheel loader V1 to accelerate and travel.

[0019] Meanwhile, the hydraulic pump 14 is driven by the engine 10 to supply hydraulic oil to the control valve 15, which distributes the hydraulic oil to drive the steer cylinder 11, lift cylinder 12, bucket cylinder 13, and brakes 14F, 14R. The steer cylinder 11, lift cylinder 12, and bucket cylinder 13 expand and contract with the supply of hydraulic oil, thereby changing the angle between the front and rear of the vehicle body, the angle of the lift arm 2 relative to the front of the vehicle body, and the angle of the bucket 1 (see also Figure 1). Furthermore, when the brakes 14F, 14R are closed by the hydraulic oil, the rotation of the tires 21FR, 21FL, 21RR, and 21RL is suppressed, and the wheel loader V1 decelerates and stops.

[0020] The control system also includes an automatic driving control device 100, an engine control device 500, a hydraulic control device 600, a travel control device 700, a user interface 60, a positioning device 51, and a load measuring device 52. The positioning device 51 acquires information on the current position and vehicle body orientation (position and orientation information) of the wheel loader V1. Here, the vehicle body orientation of the wheel loader V1 is, for example, the direction facing forward of the wheel loader V1 when the front and rear vehicle bodies of the wheel loader V1 are aligned in a straight line in the fore-and-aft direction. In this embodiment, the positioning device 51 is a Global Navigation Satellite System (GNSS), but this embodiment is not limited to this. The positioning device 51 may also be configured with a known Simultaneous Localization and Mapping (SLAM) system using a camera or Light Detection and Ranging (LiDAR). The load measuring device 52 is configured to estimate the weight of the load in the bucket 1 (live load) from the attitude of the bucket 1, which is the work tool, and the pressures of the lift cylinder 12 and the bucket cylinder 13. The user interface 60 is a PC, tablet terminal, smartphone, or the like, but may also be any other device that can input work instructions, which will be described later.

[0021] The automatic driving control device 100 generates an engine control signal, a hydraulic control signal, and a travel control signal in response to work instructions from the user interface 60, position and orientation information from the positioning device 51, and load information from the load measuring device 52, and transmits these signals to the engine control device 500, hydraulic control device 600, and travel control device 700, respectively. In response to these signals, the engine control device 500 controls the rotation speed of the engine 10, the hydraulic control device 600 controls the opening and closing degree of the control valve 15, and the travel control device 700 controls the gear ratio and rotation direction of the driving force transmission device 22.

[0022] 3 is a functional block diagram of an automatic driving control device 100 according to an embodiment of the present invention. In FIG. 3, the automatic driving control device 100 includes a behavior management unit 110, a route planning unit 120, an action generation unit 130, and a road surface gradient information storage unit 140.

[0023] The behavior management unit 110 receives work instructions from the user interface 60, position and orientation information from the positioning device 51, and load information from the load measuring device 52, determines the operation mode of the wheel loader V1, and sends this to the operation generation unit 130, while also calculating a target position and sending it to the path planning unit 120. Here, the target positions are the excavation position, the turning position when moving from the excavation position to the loading position, the loading position, the turning position when moving from the loading position to the next excavation position, and the vehicle body orientation at each position.

[0024] The route planning unit 120 receives the target position from the behavior management unit 110, position and orientation information from the positioning device 51, and road surface gradient information from the road surface gradient information storage unit 140, calculates the target route (also called the travel route or driving route) from the current position to the target position, and transmits it to the action generation unit 130.

[0025] The motion generation unit 130 receives the operation mode from the behavior management unit 110, the target route from the route planning unit 120, and position and orientation information from the positioning device 51, and generates traveling operations for the wheel loader V1 so that the current position information of the wheel loader V1 follows the target route, and also generates work operations for the bucket 1, such as digging, loading, and dumping, according to the operation mode, and transmits these as a traveling control signal and a hydraulic control signal to the traveling control device 700 and the hydraulic control device 600, respectively. The motion generation unit 130 also calculates the required engine speed from the traveling operation and the work operation, and transmits this as an engine control signal to the engine control device 500. For example, similar to conventional manual operation, the traveling control signal may be the amount of accelerator and brake pedal operation, the amount of steering, and a switching signal for a forward / reverse switch, and the hydraulic control signal may be the amount of lever operation for the lift arm 2 and the bucket 1.

[0026] The road surface gradient information storage unit 140 stores gradient information (road surface gradient information) of the road surface on which the wheel loader V1 travels, and outputs this information to the route planning unit 120. The road surface gradient information stored in the road surface gradient information storage unit 140 is, for example, information in the form of a map, and includes information on vectors (hereinafter referred to as road surface gradient vectors) that represent the position, magnitude, and direction of the road surface gradient.

[0027] 4 is a flowchart showing the calculation process performed by the behavior management unit 110. In FIG. 4, first, in step S1100, it is confirmed whether or not a work instruction transmitted from the user interface 60 has been received, and if so, the process proceeds to step S1101. The work instruction includes information such as the excavation position where earth and sand are to be excavated, the loading position where the excavated earth and sand are to be loaded onto a dump truck or the like, and the weight of the load to be loaded into the bucket 1.

[0028] In step S1101, the self-position and orientation information is acquired from the positioning device 51, and the load information is acquired from the load measuring device 52, and the process proceeds to step S1102.

[0029] In step S1102 and thereafter, a process of selecting a target position and an operation mode from the load information and the self-position and orientation information is performed. First, in step S1102, the presence or absence of a load is confirmed from the load information acquired from the load measuring device 52. If there is no load, the process proceeds to step S1103, and if there is load, the process proceeds to step S1123.

[0030] In steps S1103 and S1123, a digging position and a loading position are set as target positions, respectively, and the process proceeds to steps S1104 and S1124.

[0031] In step S1104, it is confirmed whether the self-position of the wheel loader V1 acquired from the positioning device 51 is equal to the excavation position information included in the work instruction, and if true, the process proceeds to S1105, and if false, the process proceeds to S1115. Note that the position comparison in this step may also be made by comparing whether the self-position is within a predetermined range of the excavation position.

[0032] In step S1105, the travel mode is selected as the operation mode, which enables the wheel loader V1 to perform a travel operation with the target position as the excavation position.

[0033] Similarly, in step S1115, the excavation mode is selected as the operation mode, thereby enabling the wheel loader V1 to perform excavation operations with the target position as the excavation position.

[0034] In step S1124, it is confirmed whether the self-position of the wheel loader V1 acquired from the positioning device 51 is equal to the loading position information included in the work instruction, and if true, the process proceeds to S1125, and if false, the process proceeds to S1135. Note that the position comparison in this step may also be made by comparing whether the self-position is within a predetermined range of the loading position.

[0035] In step S1125, the transport mode is selected as the operation mode, which enables the wheel loader V1 to carry out a transport operation with the target position as the loading position.

[0036] Similarly, in step S1135, the loading mode is selected as the operation mode, thereby enabling the wheel loader V1 to carry out loading operations with the target position as the loading position.

[0037] Fig. 5 is a flowchart showing the calculation process performed by the route planning unit 120. In Fig. 5, first, in step S1200, it is confirmed whether or not a target position transmitted from the behavior management unit 110 has been received, and if so, the process proceeds to step S1201.

[0038] In step S1201, road surface gradient information is obtained from the road surface gradient information storage unit 140. The road surface gradient information includes information on the position, direction, and magnitude of the road surface gradient (road surface gradient vector).

[0039] In step S1202, a travel cost is set based on the magnitude of the road surface gradient. The travel cost is one of the indices used in route planning algorithms such as the potential method. By dividing the travel area into grids and setting a cost for each grid as information representing the ease (or difficulty) of travel, it is possible to calculate the cost of the entire route passing through the grid. Generally, in order to plan a route that reaches the target position while avoiding obstacles, high costs are set for grids that correspond to obstacles and their surrounding areas. In this step, in addition to the conventional obstacles, high travel costs are set for grids that correspond to areas with steep road surface gradients.

[0040] In step S1203, a target route from the current position to the target position is planned using the travel cost set in step S1202 and a potential method such as Dijkstra's algorithm, and the process proceeds to step S1204.

[0041] In step S1204, it is determined whether the planned target route includes a road gradient of a predetermined value or more, and if true, the process proceeds to step S1205, and if false, the process proceeds to step S1510. In other words, it is determined whether or not to perform processing from step S1205 onwards based on the magnitude of the road gradient included in the planned target route.

[0042] In step S1205, it is determined whether the planned target route is not directly facing the road surface gradient. If true, the process proceeds to step S1206, and if false, the process proceeds to step S1510.

[0043] A specific method for determining whether the target route is facing the road surface gradient, performed in step S1205, will be described using the relationship diagram between the road surface gradient vector and the target route shown in FIG. 6. The road surface gradient information stored in the road surface gradient information storage unit 140 includes information on a vector (road surface gradient vector) that represents the position, magnitude, and direction of the road surface gradient. When the direction of the road surface gradient vector and the direction of the target route approximately match, it can be determined that the target route is facing the road surface gradient. In this embodiment, the angle (angular difference) θ between the direction of the target route and the direction of the road surface gradient vector is Ｓ is equal to or smaller than the predetermined value, it is determined that the target route is directly facing the road surface gradient, and the process proceeds to step S1510. Ｓ If is greater than the predetermined value, it is determined that the target route does not face the road surface gradient, and the process proceeds to step S1206.

[0044] In step S1206, a gradient section (a road section of a predetermined length) on the target route that has a road gradient of a predetermined value or more but is not directly facing the road gradient is targeted, and it is determined whether there is room to change the start point of the gradient section so that the target route is directly facing the road gradient. For example, the road width at the start point of the gradient section is compared with the vehicle width of the wheel loader V1, and the θ ＳIf there is sufficient road width in the direction in which the gradient becomes smaller, it is determined that there is room to change the start point of the gradient section, and the process proceeds to step S1208. If it is determined that there is no room to change the start point of the gradient section, the process proceeds to step S1307.

[0045] In step S1307, the θ Ｓ If there is room to change the end point of the gradient section, the process proceeds to step S1308; if there is no room to change the end point of the gradient section, the process proceeds to step S1410.

[0046] In step S1208, for a road section where the starting point can be changed, the end point of the road section is set as a waypoint, and the process proceeds to step S1209.

[0047] Similarly, in step S1308, for a road section where the end point can be changed, the start point of the road section is set as a waypoint, and the process proceeds to step S1209.

[0048] In step S1209, the target route passes through the set via point and faces the road surface gradient of the gradient section (the angle θ between the direction of the target route and the direction of the road surface gradient vector is Ｓ is equal to or less than a predetermined value), and the process returns to step S1204. In other words, the target route is corrected so that either the start point or the end point of the road gradient section is set as a via point, and at the same time, the target route passes through the set via point and faces the road gradient of the gradient section (the angle θ between the direction of the target route and the direction of the road gradient vector is Ｓ The method for correcting the target route will be described later.

[0049] In step S1510, it is determined that the target route does not include a road surface gradient of a predetermined value or more (false in S1204), or that the target route includes a road surface gradient of a predetermined value or more but is directly facing the road surface gradient (false in S1205), and the fact that the route planning was successful and the planned target route are transmitted (notified) to the user interface 60 and the action generation unit 130.

[0050] In step S1410, since the target route could not be corrected to face the road surface gradient included in the target route that is equal to or greater than a predetermined value (false in S1206 and S1307), a message is sent (notified) to the user interface 60 indicating that the route planning has failed and a request to change (revise) the target position.

[0051] Next, a method for correcting the target route performed in step S1209 will be described with reference to FIG.

[0052] Figure 7 is a schematic diagram showing road surface gradient vectors and a target route. In Figure 7, solid lines represent contour lines, and arrows extending from the center of each grid represent road surface gradient vectors. The road surface gradient vector indicates the direction of the road surface gradient at that position by the arrow direction, and the magnitude of the road surface gradient by the arrow length (magnitude).

[0053] The route (route a) shown by the dotted arrow, which was planned using a conventional route planning method that does not consider road gradient, is basically a route planned to shorten the route length to the target position while avoiding obstacles. Therefore, the route is planned so as not to directly confront the road gradient.

[0054] The route indicated by the solid arrow (route b) sets the intersection of the end point of the gradient section and the route as a via point, passes through the via point, and the direction of the target route of the gradient section is along the direction of the road surface gradient vector (the angle θ Ｓ This is a route in which the start point of the gradient section is set as the via point so that the road surface gradient vector is equal to or less than a predetermined value. Note that, although the end point of the gradient section is set as the via point here, as shown in steps S1206 and S1307 above, if there is no room to change the start point of the gradient section, it is also possible to use the start point of the gradient section as the via point and change the end point of the gradient section so that it is aligned with the direction of the road surface gradient vector.

[0055] Next, another example of the method for determining whether the vehicle is facing the road surface gradient of the target route, which is performed in step S1205, will be described with reference to Figures 8 and 9. The angle θ between the direction of the road surface gradient vector and the direction of the target route ＳThe difference between this method and the facing determination method (Fig. 6) that uses the difference in elevation between the left and right wheels (at least one pair of left and right wheels) (for example, the centers of the left and right wheels) of the wheel loader V1 is that Fig. 8 is a diagram that schematically shows a route on a road surface gradient, and Fig. 9 is a diagram that schematically shows the transition of the difference in elevation between the left and right wheels of the wheel loader V1 when traveling on the route.

[0056] As in Figure 7 , the route indicated by the dotted arrow (route a) is an example of a route planned using a conventional route planning method that does not take road surface gradient into consideration, and therefore the route is planned so as to basically shorten the route length to the target position while avoiding obstacles. This route a does not face the road surface gradient, i.e., it approaches the road surface gradient at an angle, so as shown in Figure 9 , a difference in elevation occurs between the left and right wheels of the wheel loader V1 when traveling on the gradient. If the difference in elevation between the left and right wheels is equal to or greater than the road surface gradient determination threshold, it is determined that the target route does not face the road surface gradient (step S1205 in Figure 5 ), and that road surface gradient section is subject to correction. The specific method for correcting the target route is the same as the method described in Figure 7 , in which either the start point or the end point of the road surface gradient section is set as a waypoint, and the other point is set as a waypoint so that the other point passes through the waypoint and the difference in elevation between the left and right wheels of the wheel loader V1 is equal to or less than the road surface gradient determination threshold. The route indicated by the solid arrow (route b) is a target route that has been corrected so that the difference in height between the left and right wheels of the wheel loader V1 is equal to or less than the road surface gradient determination threshold, with the end point of the road surface gradient section being the via point.

[0057] As described above, by planning a target route so as to face a slope with a gradient, it is possible to prevent the behavior of the vehicle body from becoming unstable when traveling on a slope.

[0058] [Summary] As explained above, the control device (automatic driving control device 100) of a work machine (wheel loader V1) in this embodiment is a control device for a work machine that plans a target route, which is a movement route to a target position (set by the behavior management unit 110) (in other words, a movement route for moving the work machine from its current position to the target position), and automatically travels by following the planned target route, and the control device is equipped with a route planning unit 120 that plans the target route based on the current position of the work machine (acquired by the positioning device 51) and the target position, and the route planning unit 120 corrects the target route based on gradient information of the road surface on the target route.

[0059] The route planning unit 120 calculates the angle difference (the angle θ Ｓ ) and correct the target path.

[0060] The route planning unit 120 calculates the angle difference (the angle θ Ｓ ) is equal to or less than a predetermined value (so that the target route faces the road surface gradient) (step S1205 and subsequent steps).

[0061] The route planning unit 120 determines whether or not to modify the target route based on the magnitude of the gradient of the road surface on the target route (step S1204).

[0062] The route planning unit 120 calculates the angle difference (the angle θ Ｓ ) exceeds a predetermined value (the target route is not directly facing the road surface gradient) (step S1205), and if it is determined that the angular difference exceeds the predetermined value (the target route is not directly facing the road surface gradient) (true in step S1205), either the start point or the end point of the target route in the section with the road surface gradient is set as a via point (steps S1208, S1308), and the target route is corrected so that it passes through the via point and the angular difference becomes equal to or less than the predetermined value (the target route is directly facing the road surface gradient of the gradient section) (step S1209).

[0063] The gradient information of the road surface on the target route includes a road surface gradient vector including information on the position, direction, and magnitude of the gradient of the road surface, and the route planning unit 120 determines the angular difference (the angle θ ) between the direction of the target route and the direction of the road surface gradient vector based on a comparison between the direction of the target route and the direction of the road surface gradient vector (FIG. 6). Ｓ ) exceeds a predetermined value (the target route is not directly facing the road surface gradient) (step S1205), and if it is determined that the angular difference exceeds the predetermined value (the target route is not directly facing the road surface gradient) (true in step S1205), either the start point or the end point of the target route in the section with the road surface gradient is set as a via point (steps S1208, S1308), and the target route is corrected so that it passes through the via point and the angular difference becomes equal to or less than the predetermined value (the target route is directly facing the road surface gradient of the gradient section) (step S1209).

[0064] The work machine has at least one pair of left and right wheels, and the route planning unit 120 determines the angle difference (the angle θ ) between the direction of the target route and the direction of the gradient of the road surface on the target route based on a comparison (FIG. 9) between the height difference between the pair of left and right wheels and a preset road surface gradient determination threshold. Ｓ ) exceeds a predetermined value (the target route is not directly facing the road surface gradient) (step S1205), and if it is determined that the angular difference exceeds the predetermined value (the target route is not directly facing the road surface gradient) (true in step S1205), either the start point or the end point of the target route in the section with the road surface gradient is set as a via point (steps S1208, S1308), and the target route is corrected so that it passes through the via point and the angular difference becomes equal to or less than the predetermined value (the target route is directly facing the road surface gradient of the gradient section) (step S1209).

[0065] The route planning unit 120 determines whether or not to modify the target route based on the magnitude of the gradient of the road surface on the target route (step S1204).

[0066] The control device includes an operation generation unit 130 that generates control signals for causing the work machine to travel while following the target route planned by the route planning unit 120, and the route planning unit 120 determines whether the target route includes a gradient of the road surface that is equal to or greater than the predetermined magnitude (step S1204), and if it is determined that the target route includes a gradient of the road surface that is equal to or greater than the predetermined magnitude (true in step S1204), calculates an angular difference (angle θ) between the direction of the target route and the direction of the gradient of the road surface. Ｓ ) exceeds a predetermined value (the target route is not directly facing the road surface gradient) (step S1205), and if it is determined that the angle difference exceeds the predetermined value (the target route is not directly facing the road surface gradient) (step S1205: true), either the start point or the end point of the target route in the section of the road surface gradient is set as a via point (steps S1208, S1308), and the target route is adjusted so that the target route passes through the via point and the angle difference becomes equal to or less than the predetermined value (the target route is directly facing the road surface gradient of the gradient section). (step S1209), and if it is determined that the target route does not include a gradient of the road surface equal to or greater than the predetermined magnitude (false in step S1204), or if it is determined that the target route includes a gradient of the road surface equal to or greater than the predetermined magnitude but the angular difference does not exceed the predetermined value (is equal to or less than the predetermined value) (the target route is directly facing the road surface gradient) (false in step S1205), the target route is output to the action generation unit 130 (as the final target route) without being modified (step S1510).

[0067] The work machine is also equipped with an articulated type (bending type) steering mechanism.

[0068] According to this embodiment, the vehicle can travel stably on a slope with an incline, and therefore the vehicle's behavior can be prevented from becoming unstable when traveling on a route that includes a slope.

[0069] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and includes various modifications. For example, while the above-described embodiments apply the present invention to a wheel loader, the application of the present invention is not limited to this and can also be applied to work machines such as dump trucks. Furthermore, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those having all of the configurations described.

[0070] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The above-described configurations, functions, etc. may also be implemented in software, with a processor interpreting and executing a program that implements each function. Information such as the program, table, and file that implements each function can be stored in a memory, a storage device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

[0071] In addition, the control lines and information lines shown are those that are considered necessary for the explanation, and do not necessarily show all the control lines and information lines in the product. In reality, it can be assumed that almost all components are interconnected.

[0072] 1... bucket, 2... lift arm, 3... bell crank, 4... bucket link, 51... positioning device, 52... load measuring device, 60... user interface, 100... autonomous driving control device (control device), 110... behavior management unit, 120... route planning unit, 130... action generation unit, 140... road surface gradient information storage unit, 500... engine control device, 600... hydraulic control device, 700... travel control device, V1... wheel loader (work machine)

Claims

1. A control device for a work machine that plans a target path, which is a movement path to a target position, and automatically travels following the planned target path, the control device including a path planning unit that plans the target path based on the current position and the target position of the work machine, the path planning unit being characterized by correcting the target path based on gradient information of a road surface on the target path.

2. The control device for a work machine according to claim 1, wherein the path planning unit corrects the target path based on an angular difference between a direction of the target path and a direction of a gradient of a road surface on the target path.

3. The control device for a work machine according to claim 2, wherein the path planning unit corrects the target path such that an angular difference between a direction of the target path and a direction of a gradient of a road surface on the target path is equal to or less than a predetermined value.

4. The control device for a work machine according to claim 2, wherein the path planning unit determines whether to correct the target path based on a magnitude of a gradient of a road surface on the target path.

5. The control device for a work machine according to claim 1, wherein the path planning unit determines whether an angular difference between a direction of the target path and a direction of a gradient of a road surface on the target path exceeds a predetermined value, and when it is determined that the angular difference exceeds the predetermined value, sets either a start point or an end point of the target path in a section of the gradient of the road surface as a passing point, and corrects the target path so as to pass through the passing point and the angular difference becomes equal to or less than the predetermined value.

6. The control device for a work machine according to claim 5, wherein the gradient information of the road surface on the target path includes a road surface gradient vector including information on a position, a direction, and a magnitude of the gradient of the road surface, and the path planning unit determines whether the angular difference exceeds a predetermined value based on a comparison between a direction of the target path and a direction of the road surface gradient vector.

7. In the control device for a working machine according to claim 1, the working machine has at least one pair of left and right wheels, the path planning unit determines whether an angular difference between a direction of the target path and a direction of a gradient of a road surface on the target path exceeds a predetermined value based on a comparison between a height difference between the pair of left and right wheels and a preset road surface gradient determination threshold value, and when it is determined that the angular difference exceeds the predetermined value, sets either a start point or an end point of the target path in a section of the gradient of the road surface as a waypoint, and corrects the target path so as to pass through the waypoint and the angular difference becomes equal to or less than the predetermined value. A control device for a working machine, characterized in that.

8. In the control device for a working machine according to claim 5, the path planning unit determines whether to correct the target path based on a magnitude of a gradient of a road surface on the target path. A control device for a working machine, characterized in that.

9. In the control device for a working machine according to claim 8, the control device includes an operation generation unit that generates a control signal for causing the working machine to travel following the target path planned by the path planning unit, the path planning unit determines whether the target path includes a gradient of the road surface having a predetermined magnitude or more, when it is determined that the target path includes a gradient of the road surface having a predetermined magnitude or more, determines whether an angular difference between a direction of the target path and a direction of the gradient of the road surface exceeds a predetermined value, and when it is determined that the angular difference exceeds the predetermined value, sets either a start point or an end point of the target path in a section of the gradient of the road surface as a waypoint, and corrects the target path so as to pass through the waypoint and the angular difference becomes equal to or less than the predetermined value, when it is determined that the target path does not include a gradient of the road surface having a predetermined magnitude or more, or when it is determined that the angular difference does not exceed the predetermined value when it is determined that the target path includes a gradient of the road surface having a predetermined magnitude or more, outputs to the operation generation unit without correcting the target path. A control device for a working machine, characterized in that.

10. In the control device for a working machine according to claim 1, the working machine is a working machine provided with an articulated steering mechanism. A control device for a working machine, characterized in that.

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