Work vehicles

Abstract

To provide a work vehicle capable of suppressing contact with obstacles in a work vehicle realizing steering by bending a vehicle body.SOLUTION: In a work vehicle including a front vehicle body, a rear vehicle body connected to the front vehicle body so as to be rotatable in a left and right direction, and a working machine provided in front of the front vehicle body, the front vehicle body and the rear vehicle body are provided so as to be bendable. The work vehicle also includes an obstacle detection device that detects a position and a shape of an obstacle existing around the work vehicle, and a control device that controls a bending angle of the front and rear vehicle bodies. The control device calculates a maximum vehicle body occupation area which is an area occupied by the work vehicle due to changes in the bending angle of the front and rear vehicle bodies. When it is determined that there is an obstacle in the maximum vehicle body occupation area, the control device calculates a distance between the work vehicle and the obstacle based on detection results from the obstacle detection device, calculates a limit value of the bending angle to prevent the work vehicle from coming into contact with the obstacle based on the calculated distance, and controls the bending angle of the front and rear vehicle bodies so that they do not exceed the limit value.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a work vehicle, such as a wheel loader, whose body is steered by bending. [Background technology]

[0002] For example, a work vehicle such as a wheel loader is known, which has a lift arm constituting a work machine and a bucket tiltably attached to the tip of the lift arm, and uses the bucket to excavate by scooping up soil and sand, move the scooped soil, and load the scooped soil into a transport vehicle or the like. In addition to the work machine, the wheel loader is equipped with a traveling device for traveling the vehicle and a steering device for steering by bending the body. Since a bucket with a long width is used for the wheel loader, it is necessary to control the traveling of the work machine, which has a wide range of movement, so that it does not come into contact with surrounding obstacles. In particular, obstacle avoidance is an important function required for a work vehicle equipped with an autonomous driving function.

[0003] A known prior art related to such obstacle avoidance technology is described, for example, in Patent Document 1. Patent Document 1 discloses a technology that ensures a distance between the vehicle body and the obstacle by narrowly restricting the driving range near the obstacle in terms of the lateral position of the vehicle, thereby avoiding contact with the obstacle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 163790 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional technology only ensures the distance between the representative position of the vehicle body and the obstacle, and does not take into consideration vehicles such as wheel loaders whose width of the vehicle body varies. Specifically, in an articulating work vehicle that realizes steering by bending the vehicle body using a bending mechanism between the front and rear wheels of the vehicle, the amount of overhang of the vehicle body in the width direction changes due to bending, so there is a risk that contact with an obstacle cannot be avoided by only restricting the width direction position of the vehicle body. In particular, in a work vehicle equipped with a work machine having a bucket with a long width dimension, the amount of overhang from the bending point to the work machine becomes large, so the amount of overhang of the vehicle body in the lateral direction due to bending becomes larger, making it even more difficult to avoid contact with an obstacle.

[0006] The present invention has been made in consideration of the above, and aims to provide a work vehicle that achieves steering by bending the body and that can reduce contact with obstacles. [Means for solving the problem]

[0007] The present application includes multiple means for solving the above problem, and one example is a work vehicle comprising a front body having a pair of left and right wheels, a rear body having a pair of left and right wheels connected to the front body so as to be rotatable in the left and right direction, and a work machine mounted in front of the front body, wherein the front body and the rear body are flexibly mounted, the work vehicle is provided with an obstacle detection device that detects the position and shape of an obstacle present around the work vehicle, and a control device that controls the bending angle of the front body and the rear body, the control device calculates a maximum body occupancy area, which is the area occupied by the work vehicle, by changing the bending angle of the front body and the rear body, and when it is determined that the obstacle is present in the maximum body occupancy area, calculates the distance between the work vehicle and the obstacle based on the detection result detected by the obstacle detection device, calculates a limit value of the bending angle at which the work vehicle will not come into contact with the obstacle based on the calculated distance, and controls the bending angle of the front body and the rear body so as not to exceed the limit value. Effect of the Invention

[0008] According to the present invention, it is possible to prevent a work vehicle that achieves steering by bending the body from coming into contact with an obstacle. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic external appearance of a wheel loader, which is an example of a work vehicle. [Diagram 2] 1 is a diagram showing an outline of the overall configuration of a control device for controlling a bending angle of a wheel loader together with related configurations. [Diagram 3] FIG. 13 is a diagram showing an example of a maximum vehicle body occupancy area. [Figure 4] 4 is a flowchart of a process relating to control of a bending angle of a vehicle body. [Diagram 5] 1 is a diagram showing a schematic diagram of dumping soil into a hopper as an example of work performed by a work vehicle; [Figure 6] 13 is a diagram showing an outline of the overall configuration of a control device for controlling the bending angle of a wheel loader according to a second embodiment, together with related configurations. FIG. [Figure 7] FIG. 1 is a diagram illustrating a schematic diagram of a host vehicle and other vehicles operating at a work site. [Figure 8] FIG. 11 is a diagram showing a difference in the amount of overhang due to differences in the angle of the work implement in a wheel loader. [Figure 9] FIG. 13 is a diagram showing a difference in the maximum vehicle body occupation area due to a difference in the amount of overhang. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an articulated wheel loader will be shown as an example of a work vehicle, but the present invention can also be applied to other work vehicles such as an articulated dump truck.

[0011] <First embodiment> A first embodiment of the present invention will be described with reference to FIGS.

[0012] FIG. 1 is a side view that shows a schematic external appearance of a wheel loader that is an example of a work vehicle according to the present embodiment.

[0013] As shown in FIG. 1, the wheel loader 1 is an articulated work vehicle that includes a front body 11 (front vehicle body) having a pair of left and right front wheels 4a (wheels), a rear body 12 (rear vehicle body) that is connected to the front body 11 so as to be able to bend (rotate) in the left and right direction and has a pair of left and right rear wheels 4b (wheels), and a work implement consisting of a lift arm 2 and a bucket 3 provided in front of the front body 11. The rear body 12 includes a driver's cab 5, an engine room in which an engine 6 is mounted, and the like. Hereinafter, the members that make up the wheel loader 1, such as the front body 11, the rear body 12, the bucket 3, the front wheels 4a, and the rear wheels 4b, may be collectively referred to as the "vehicle body".

[0014] The wheel loader 1 has a working machine made up of a pair of left and right lift arms 2 attached to the front end of a front body 11 by a pair of left and right lift cylinders 7 so as to be able to swing up and down, and a bucket 3 connected to the tip of the lift arm 2 so as to be able to rotate up and down, and driven to rotate up and down by a bucket cylinder 8. The bucket 3 rotates up and down due to the expansion and contraction of the bucket cylinder 8 connected via a bell crank 9 and a bucket link 10, thereby changing the orientation of the opening of the bucket 3 up and down.

[0015] The lift cylinder 7 extends when pressure oil is supplied to the bottom chamber, causing the lift arm 2 to rotate upward (lift up), and retracts when pressure oil is supplied to the rod chamber, causing the lift arm 2 to rotate downward (lift down). The bucket cylinder 8 extends when pressure oil is supplied to the bottom chamber, causing the bucket 3 to rotate upward (tilt), and retracts when pressure oil is supplied to the rod chamber, causing the bucket 3 to rotate downward (dump).

[0016] The front body 11 and the rear body 12 are connected by a center pin 13 so as to be rotatable (bendable) in the left and right directions. A pair of left and right front wheels 4a are provided on the front body 11, and a pair of left and right rear wheels 4b are provided on the rear body 12. A pair of left and right steering cylinders 14 are provided between the front body 11 and the rear body 12 at the connection portion (left and right of the center pin 13) between the front body 11 and the rear body 12, and the wheel loader 1 can be steered by the front body 11 and the rear body 12 rotating relatively in the left and right directions due to the extension and contraction of the steering cylinders 14. For example, when the right steering cylinder 14 retracts and the left steering cylinder 14 extends, the wheel loader 1 bends to the right. Also, when the right steering cylinder 14 extends and the left steering cylinder 14 retracts, the wheel loader 1 bends to the left. The rotation angle around the center pin 13 when the wheel loader 1 bends is called the bending angle, and a state where the wheel loader 1 is not bent is taken as zero, and bending to the right is taken as a positive value.

[0017] The wheel loader 1 travels by rotating the front wheels 4a and rear wheels 4b (hereinafter, sometimes collectively referred to as the wheels 4a, 4b). In a wheel loader 1 equipped with a typical torque converter type traveling drive system, the front and rear wheels 4a and the rear wheels 4b are rotatably connected via an engine 6 and a drive train (not shown), that is, a torque converter, a transmission, a propeller shaft differential, etc. The wheel loader 1 can travel forwards and backwards by transmitting the torque generated by the engine 6 to the wheels 4a, 4b via a power train composed of the torque converter, etc. In addition, the wheel loader 1 can be steered while traveling by bending its wheels.

[0018] An obstacle detection device 15 for detecting the position and shape of obstacles around the wheel loader 1 is installed in a position where the surroundings can be seen, such as the top of the cab 5 of the wheel loader 1. For example, the obstacle detection device 15 uses LiDAR, which measures the distance from the time it takes for a laser light irradiated to the surroundings to be reflected back and the direction from the irradiation angle, as a method of measuring obstacles, and a camera that calculates the distance and direction mainly from the analysis of multiple images. However, the measurement method is not limited to these, and other measurement methods may be used as long as the position and shape of the obstacle can be measured from a data group of the distance and direction of the surrounding obstacles. Since the mounting position of the obstacle detection device 15 on the vehicle body is known from design information, etc., it is possible to detect the relative position of the obstacle with respect to the vehicle body.

[0019] A vehicle body position measuring device 16 that detects the position of the wheel loader 1 at the work site is provided on the upper part of the rear body 12 behind the cab 5. The vehicle body position measuring device 16 measures coordinates in a site coordinate system (or an earth coordinate system), such as a GNSS (Global Navigation Satellite System). Since the mounting position of the vehicle body position measuring device 16 on the vehicle body, i.e., the measurement position, is known from design information etc., it is possible to calculate the position of each part of the vehicle body in the site coordinate system.

[0020] FIG. 2 is a diagram showing an outline of the overall configuration of a control device for controlling the bending angle of a wheel loader together with related configurations.

[0021] As shown in Fig. 2, the wheel loader 1 has an autonomous driving system 300 that realizes an autonomous driving function. The control device 200 calculates the bending angle (steering angle) of the wheel loader 1 taking into consideration the positional relationship between the vehicle body and an obstacle based on information from the autonomous driving system 300, and returns the calculated steering angle to the autonomous driving system 300, thereby more reliably preventing contact with the obstacle. The control device 200 includes a trajectory following unit 201, an obstacle position calculation unit 202, an obstacle interference determination unit 203, a clearance calculation unit 204, a limit bending angle calculation unit 205, and a target bending angle setting unit 206.

[0022] The trajectory tracking unit 201 calculates the bending angle of the vehicle body for the wheel loader 1 to follow the travel trajectory (travel along the travel trajectory) based on the travel trajectory of the wheel loader 1 presented by the autonomous driving system 300. The travel trajectory presented by the autonomous driving system 300 is a route that the wheel loader 1 should travel in a series of tasks at the work site, and is determined in advance in the form of continuous coordinate information on the site map information. The trajectory tracking unit 201, for example, calculates the steering amount based on a forward gaze model. This is a steering model that determines a forward gaze point set on the travel trajectory to be traveled and in front of the wheel loader 1 as a passing point for the wheel loader 1 to proceed, and determines the steering amount based on an orientation difference obtained by comparing the forward gaze point with the self-position and orientation of the wheel loader 1. Note that many steering models for trajectory tracking have been proposed, and the steering model is not limited to the forward gaze model. The trajectory tracking unit 201 calculates the bending angle of the vehicle body from the steering amount calculated by the steering model or the like, and outputs it to the target bending angle setting unit 206 as the target bending angle.

[0023] The obstacle position calculation unit 202 calculates the relative position and shape of the obstacle with respect to the vehicle body based on the detection result from the obstacle detection device 15. Since the mounting position of the obstacle detection device 15 with respect to the vehicle body is known from design information or the like, it is possible to calculate the relative position of the obstacle with respect to the vehicle body from the detection result of the obstacle detection device 15. The obstacle position calculation unit 202 outputs the calculated position and shape of the obstacle to the obstacle interference determination unit 203 and the clearance calculation unit 204.

[0024] The obstacle interference determination unit 203 determines, based on the calculation result from the obstacle position calculation unit 202, whether or not there is a possibility of interference between the obstacle and the vehicle body.

[0025] FIG. 3 is a diagram showing an example of the maximum vehicle body occupation area.

[0026] The obstacle interference determination unit 203 calculates, for example, as shown in FIG. 3, the area through which the vehicle body passes when the bending angle of the vehicle body of the wheel loader 1 changes to the maximum, that is, when the bending angle changes from a state of 0 (zero) (see reference line 301) to a state of the vehicle body at maximum left bending around the center pin 13 at 302 to a state of the vehicle body at maximum right bending as a maximum vehicle body occupation area 304. That is, the maximum vehicle body occupation area 304 is the area occupied by the vehicle body of the wheel loader 1 due to the change in bending angle, that is, the area occupied by the vehicle body on a plane when the vehicle body is viewed from above. Then, by determining whether or not the maximum vehicle body occupation area 304 overlaps with the occupation area of ​​the obstacle calculated from the position and shape of the obstacle calculated by the obstacle position calculation unit 202, it is determined whether or not there is a possibility of interference between the vehicle body and the obstacle. The obstacle interference determination unit 203 outputs the determination result to the target bending angle setting unit 206.

[0027] The clearance calculation unit 204 calculates the distance (clearance information) between the vehicle body and the obstacle in the current vehicle body state (bending angle) based on the calculation result from the obstacle position calculation unit 202. The clearance calculation unit 204 calculates the closest distance between the vehicle body contour and the obstacle in the current vehicle body bending state as the clearance information. In the clearance information, the direction in which the obstacle exists as seen from the vehicle body is also expressed by a sign or the like. For example, if a right bend is defined as positive, the distance to the obstacle on the right side of the vehicle body is expressed as positive, and the distance to the obstacle on the left side is expressed as negative. The clearance calculation unit 204 outputs the calculation result to the limit bending angle calculation unit 205.

[0028] The limit bending angle calculation unit 205 determines the maximum bending angle of the vehicle body under the condition of not contacting the obstacle, that is, the limit value of the bending angle of the vehicle body (limit bending angle), based on the calculation result from the clearance calculation unit 204, that is, the distance between the vehicle body and the obstacle. The limit bending angle calculation unit 205 outputs the calculation result to the target bending angle setting unit 206.

[0029] When the determination result of the obstacle interference determination unit 203 indicates that the vehicle body will not interfere with surrounding obstacles (there is no possibility of interference) at any bending angle, the target bending angle setting unit 206 adopts the target bending angle input from the trajectory tracking unit 201 as it is, and outputs it to the autonomous driving system 300 as the setting value of the target bending angle. On the other hand, when the determination result of the obstacle interference determination unit 203 indicates that the vehicle body may interfere with an obstacle, the target bending angle is limited based on the limit bending angle calculated by the limit bending angle calculation unit 205. In other words, the target bending angle setting unit 206 adopts the angle having the same sign and the smaller absolute value of the target bending angle and limit bending angle input from the trajectory tracking unit 201 as the setting value of the target bending angle, and outputs it to the autonomous driving system 300.

[0030] The autonomous driving system 300 controls the steering cylinder 14 to control the bending angle of the vehicle body based on the target bending angle set by the target bending angle setting unit 206, thereby realizing the desired steering so that the wheel loader 1 follows the travel trajectory while suppressing contact with obstacles due to bending.

[0031] FIG. 4 is a flowchart of a process relating to control of the bending angle of the vehicle body.

[0032] As shown in FIG. 4, first, the trajectory following unit 201 calculates a steering flexion angle for following the trajectory (step S400).

[0033] Next, the obstacle detection device 15 measures the position and shape of the obstacle, and the obstacle position calculation unit 202 calculates the position and shape of the obstacle relative to the vehicle body (step S410). Next, the obstacle interference determination unit 203 determines whether or not there is a possibility of interference between the obstacle and the vehicle body based on the position and shape of the obstacle calculated by the obstacle position calculation unit 202 (step S420), and determines whether or not the determination result indicates that there is interference between the obstacle and the vehicle body (step S430).

[0034] If the determination result in step S430 is NO, that is, if it is determined that there is no possibility of interference between the vehicle body and an obstacle, the target bending angle setting unit 206 returns the steering angle (i.e., the target bending angle) input from the autonomous driving system 300 to the autonomous driving system 300 as the setting value of the target bending angle (step S461), and the autonomous driving system 300 controls the steering cylinder 14 based on the setting value of the target bending angle from the target bending angle setting unit 206 (step S480), and the processing ends.

[0035] Furthermore, if the judgment result in step S430 is YES, that is, if it is judged that there is a possibility of interference between the vehicle body and the obstacle, the clearance calculation unit 204 calculates the distance between the vehicle body and the obstacle (step S440), and the limit bending angle calculation unit 205 determines the limit value of the vehicle body bending angle (limit bending angle) at which the vehicle body will not come into contact with the obstacle based on the calculated distance between the vehicle body and the obstacle (step S450).

[0036] Next, it is determined whether the steering angle (target bending angle) input from the autonomous driving system 300 is greater than the limit bending angle (step S460). If the determination result is NO, i.e., if the vehicle body does not come into contact with an obstacle, the target bending angle setting unit 206 returns the steering angle input from the autonomous driving system 300 (i.e., the target bending angle) to the autonomous driving system 300 as the setting value of the target bending angle (step S461). The autonomous driving system 300 controls the steering cylinder 14 based on the setting value of the target bending angle from the target bending angle setting unit 206 (step S480), and the processing ends.

[0037] Furthermore, if the determination result in step S460 is YES, that is, if there is a possibility that the vehicle body will come into contact with an obstacle, the target bending angle setting unit 206 returns the limit bending angle to the autonomous driving system 300 as the setting value of the target bending angle to limit the limit bending angle as an upper limit (step S461), and the autonomous driving system 300 controls the steering cylinder 14 based on the setting value of the target bending angle from the target bending angle setting unit 206 (step S480), and ends the processing.

[0038] The effect of the present embodiment configured as above, that is, the effect of suppressing contact between the vehicle body and an obstacle, will be described.

[0039] FIG. 5 is a diagram that illustrates the dumping of soil into a hopper, as an example of work performed by a work vehicle.

[0040] As shown in FIG. 5, the most important task of the wheel loader 1, which is a work vehicle, is to move earth and sand. For example, a typical task is to excavate and transport earth and sand from a stockpile and load it onto the bed of a dump truck. In addition, when dumping earth and sand as material into a plant, the task of dumping earth and sand into a hopper 503 installed in a building is often seen. In this case, the position of the object to be loaded does not change every time it is loaded, as in the case of a dump truck, but the earth and sand must be dumped accurately into an area smaller than the bed of a dump truck. In addition, the hopper 503 is often installed inside a building, and a roof for protection from the rain is often installed, so that pillars 502a, 502b, 502c, 502d supporting the rain protection may be present around the hopper. In this case, there is often not enough space between the width of the bucket 3 of the work machine and the space between the pillars 502a, 502b. When traveling toward such a hopper 503, the distance 504 between the bucket 3 and the building is very narrow, and the vehicle body is highly likely to come into contact with the building due to lateral overhang caused by steering. In this embodiment, in such a work environment, the bending angle of the vehicle body can be limited based on the distance 504 between the bucket 3 and the building (for example, pillar 502a) so that the vehicle body does not come into contact with an obstacle, making it possible to effectively prevent contact between the wheel loader 1 and the pillar 502a of the building, etc.

[0041] <Second embodiment> A second embodiment of the present invention will be described with reference to FIG.

[0042] In the first embodiment, the target bending angle of the vehicle body is calculated based on the traveling trajectory presented by the autonomous driving system 300, whereas in the present embodiment, the future traveling trajectory is predicted from the current bending angle made by the steering command given from the outside, and by determining whether or not the vehicle body interferes with an obstacle within the vehicle body movable range around the predicted future traveling trajectory, i.e., around the trajectory along which the vehicle body moves by traveling, the presence or absence of interference with an obstacle not only around the current vehicle but also around the future vehicle position is determined. In addition, in the present embodiment, the steering command that determines the bending angle of the vehicle body is given from the outside, so that it can be applied not only to the case of autonomous traveling but also to manual steering traveling by an operator.

[0043] In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0044] FIG. 6 is a diagram showing a schematic diagram of the overall configuration of a control device for controlling the bending angle of a wheel loader according to this embodiment, together with related configurations.

[0045] As shown in Fig. 6, the wheel loader 1 has a traveling system 300A that realizes a driving function. The control device 200A calculates the bending angle (steering angle) of the wheel loader 1 taking into consideration the positional relationship between the vehicle body and an obstacle based on information from a handle 507 installed in the driver's cab 5, and outputs the calculated steering angle to the traveling system 300A, thereby more reliably preventing contact with the obstacle. The control device 200A includes a traveling trajectory prediction unit 501, an obstacle position calculation unit 202, an obstacle interference determination unit 203a, a clearance calculation unit 204a, a limit bending angle calculation unit 205a, and a target bending angle setting unit 206a.

[0046] The travel trajectory prediction unit 501 calculates a predicted value of the future travel trajectory of the wheel loader 1 based on the current vehicle body bending angle. Although not described in detail here, the curvature of the travel trajectory is calculated approximately proportional to the vehicle body bending angle due to the geometric relationship when turning in an articulated work vehicle, so it is possible to formulate the predicted value of the future travel trajectory using this relationship, for example. The travel trajectory prediction unit 501 outputs the calculated travel trajectory predicted value to the obstacle interference determination unit 203a and the clearance calculation unit 204a.

[0047] The obstacle position calculation unit 202 calculates the relative position and shape of the obstacle with respect to the vehicle body based on the detection result from the obstacle detection device 15. Since the mounting position of the obstacle detection device 15 with respect to the vehicle body is known from design information or the like, it is possible to calculate the relative position of the obstacle with respect to the vehicle body from the detection result of the obstacle detection device 15. The obstacle position calculation unit 202 outputs the calculated position and shape of the obstacle to the obstacle interference determination unit 203a and the clearance calculation unit 204a.

[0048] The obstacle interference determination unit 203a compares the calculation result from the obstacle position calculation unit 202 with the travel trajectory prediction value from the travel trajectory prediction unit 501 and determines whether or not there is a possibility of interference between the obstacle and the vehicle body. The obstacle interference determination unit 203a outputs the determination result to the target bending angle setting unit 206a.

[0049] The clearance calculation unit 204a compares the calculation result from the obstacle position calculation unit 202 with the travel trajectory prediction value from the travel trajectory prediction unit 501, and calculates the distance (clearance information) between the vehicle body and the obstacle in the future based on the calculation result from the obstacle position calculation unit 202. The clearance calculation unit 204a outputs the calculation result to the limit bending angle calculation unit 205a.

[0050] The limit bending angle calculation unit 205a determines the maximum bending angle of the vehicle body under the condition of not contacting the obstacle, that is, the limit value (limit bending angle) of the bending angle of the vehicle body, based on the calculation result from the clearance calculation unit 204a, that is, the distance between the vehicle body and the obstacle in the future. The limit bending angle calculation unit 205a outputs the calculation result to the target bending angle setting unit 206a.

[0051] When the judgment result of the obstacle interference judgment unit 203a is that the vehicle body will not interfere with surrounding obstacles on the predicted travel trajectory of the wheel loader 1 (there is no possibility of interference), the target bending angle setting unit 206a adopts the target bending angle input from the handle 507 as it is, and outputs it to the traveling system 300A as the setting value of the target bending angle. On the other hand, when the judgment result of the obstacle interference judgment unit 203a is that there is a possibility of interference between the vehicle body and an obstacle on the predicted travel trajectory of the wheel loader 1, the target bending angle is limited based on the limit bending angle calculated by the limit bending angle calculation unit 205a. In other words, the target bending angle setting unit 206a adopts the angle with the same sign and smaller absolute value of the target bending angle and limit bending angle input from the handle 507 as the setting value of the target bending angle, and outputs it to the traveling system 300A.

[0052] The traveling system 300A controls the steering cylinder 14 to control the bending angle of the vehicle body based on the target bending angle set by the target bending angle setting unit 206a, thereby enabling the wheel loader 1 to achieve the steering desired by the operator while suppressing contact with obstacles due to bending.

[0053] The other configurations are similar to those of the first embodiment.

[0054] The present embodiment configured as above can also provide the same effects as the first embodiment.

[0055] Note that, in this embodiment, an example is given of avoiding interference with an obstacle in a work vehicle that is manually steered; however, the present invention can also be applied to an autonomous driving system by configuring the steering command input to be provided from an autonomous driving system (not shown).

[0056] <Modifications of the First and Second Embodiments> A modified example of the first and second embodiments of the present invention will be described below. In this modified example, the same components as those in the first and second embodiments are designated by the same reference numerals, and the description thereof will be omitted.

[0057] In the first and second embodiments, an obstacle detection device 15 such as a LiDAR that measures distance based on the time it takes for a laser beam emitted to the surroundings to be reflected back and a direction based on the irradiation angle, or a camera that calculates distance and direction mainly by analyzing multiple images, is installed in a position where the surroundings can be seen, such as above the cab 5. In contrast, in this modified example, obstacle information written on a pre-created map of the surroundings of the vehicle is used.

[0058] For example, information on fixed obstacles such as buildings whose positions and shapes are clearly known in advance can be recorded on a map in advance, and the positions and shapes of surrounding obstacles can be reconstructed by comparing the map with the vehicle's position. It is also possible to supply a map created using obstacle information collected by an obstacle measuring device not mounted on the vehicle, specifically, by surrounding vehicles, or obstacle information collected by a measuring device fixed on the ground, via data communication, and use the map. In this case, it is possible to provide the ground base station with a processing device that consolidates the collected obstacle information and integrates it into a map.

[0059] The other configurations are similar to those of the first and second embodiments.

[0060] With this modified example configured as above, the same effects as those of the first and second embodiments can be obtained.

[0061] Note that the system may be configured to detect obstacles by combining the detection results from the obstacle detection device shown in the first and second embodiments with obstacle information previously recorded on the map shown in this modified example.

[0062] <Third embodiment> A third embodiment of the present invention will be described with reference to FIG.

[0063] In the first and second embodiments, an example was described in which an obstacle detection device 15 such as a LiDAR that measures distance based on the time it takes for a reflected laser beam emitted to the surroundings to return and a direction based on the irradiation angle, or a camera that calculates distance and direction mainly by analyzing multiple images, is installed at a position where the surroundings can be seen, such as above the cab 5. In addition, in the modified examples of the first and second embodiments, obstacle information is obtained based on a map created in advance. In contrast, in this embodiment, obstacle information is obtained based on position and attitude information sent from other vehicles present in the vicinity of the vehicle via wireless communication means or the like.

[0064] In this embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

[0065] FIG. 7 is a diagram that illustrates a state in which a host vehicle and other vehicles are operating at a work site.

[0066] As shown in Fig. 7, at a work site, in addition to a work vehicle such as the wheel loader 1, which is the own vehicle, other work vehicles such as dump trucks 1A, 1B are in operation. That is, at a work site, a situation may be considered in which the other work vehicles working in cooperation with the wheel loader 1, which is the own vehicle, become obstacles. For example, there are cases in which dump trucks 1A, 1B transporting earth and sand excavated by the wheel loader 1, which is the own vehicle, become obstacles.

[0067] In a site where autonomous work is performed, other vehicles such as the dump trucks 1A and 1B also need to travel autonomously, so it is essential to measure the self-position and attitude information of each vehicle using the vehicle body position measuring devices 16a and 16b, etc. Alternatively, even if the vehicle is manually traveled by a person, it is possible to measure the position and attitude information from the perspective of vehicle management.

[0068] Therefore, in the wheel loader 1 of this embodiment, position and attitude information of other vehicles (dump trucks 1A, 1B, etc.) and previously known dimensional information of those vehicles are acquired via communication devices 905, 905a, 905b, and contour information of the other vehicles is calculated from the acquired information and used as information indicating the position and shape of the obstacle. Then, by collating the obstacle information obtained from the information acquired from the other vehicles with contour information of the wheel loader 1, which is the vehicle itself (see maximum vehicle body occupation area 304 in Figure 3), it is possible to determine the possibility of interference between the vehicle body (the vehicle itself) and the obstacle (the other vehicle).

[0069] The other configurations are similar to those of the first and second embodiments and their modifications.

[0070] The present embodiment configured as above can also provide the same effects as the first and second embodiments and their modifications.

[0071] <Fourth embodiment> A fourth embodiment of the present invention will be described with reference to FIGS.

[0072] In this embodiment, the maximum vehicle body occupancy area is calculated taking into account the change in the amount of overhang at the front and rear of the vehicle body. In this embodiment, the same components as those in the first and second embodiments are given the same reference numerals and the description thereof is omitted.

[0073] FIG. 8 is a diagram showing the difference in the amount of overhang caused by different angles of the work implement in a wheel loader.

[0074] As shown in Figure 8, in the wheel loader 1, the amount of overhang at the front of the vehicle body changes depending on the angle of the work implement formed by the lift arm 2 and bucket 3. For example, when the position of the center pin 13 is used as a reference, the amount of overhang 71 when the lift arm is lowered is greater than the amount of overhang 72 when the lift arm is raised. Furthermore, when the amount of overhang changes, the maximum vehicle body occupation area calculated using the size of the vehicle body (for example, see maximum vehicle body occupation area 304 in Figure 3) also changes.

[0075] FIG. 9 is a diagram showing the difference in the maximum vehicle body occupation area due to the difference in the amount of overhang.

[0076] 9, when the lift arm is lowered, the bucket 3 is in position 802, which is farther from the center pin 13, and therefore obtains the maximum vehicle body occupation area 804. When the lift arm is raised, the bucket 3 is in position 803, which is relatively closer to the center pin 13, and therefore obtains the maximum vehicle body occupation area 805.

[0077] Therefore, for example, the amount of overhang is calculated based on the detection result from the angle sensor 70 provided on the rotation shaft of the lift arm 2 on the front body 11 side and the dimensional information of the vehicle body, and the maximum vehicle body occupation area is calculated from the amount of overhang. This makes it possible to calculate the maximum vehicle body occupation area more accurately. Furthermore, by using the maximum vehicle body occupation area calculated in this way, the obstacle interference determination units 203, 203a can perform determination with higher accuracy.

[0078] The other configurations are similar to those of the first and second embodiments.

[0079] The present embodiment configured as above can also provide the same effects as the first embodiment.

[0080] <Additional Notes> The present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the gist of the present invention. The present invention is not limited to those having all the configurations described in the above-described embodiments, and includes those in which some of the configurations are deleted. The above-described configurations, functions, etc. may be realized by designing some or all of them as an integrated circuit, for example. The above-described configurations, functions, etc. may be realized by software, in which a processor interprets and executes a program that realizes each function. [Explanation of symbols]

[0081] 1...wheel loader, 1A, 1B...dump truck, 2...lift arm, 3...bucket, 4a...front wheel, 4b...rear wheel, 5...operator cab, 6...engine, 7...lift cylinder, 8...bucket cylinder, 9...bell crank, 10...bucket link, 11...front body, 12...rear body, 13...center pin, 14...steering cylinder, 15...obstacle detection device, 16, 16a, 16b...vehicle position measuring device, 70...angle sensor, 71, 72...overhang amount, 200, 200A...control device, 201... Trajectory tracking unit, 202... obstacle position calculation unit, 203, 203a... obstacle interference determination unit, 204, 204a... clearance calculation unit, 205, 205a... limit bending angle calculation unit, 206, 206a... target bending angle setting unit, 300... autonomous driving system, 300A... driving system, 304... maximum vehicle body occupancy area, 501... driving trajectory prediction unit, 502a, 502b, 502c, 502d... pillars, 503... hopper, 504... interval, 507... handle, 804, 805... maximum vehicle body occupancy area, 905, 905a, 905b... communication device

Claims

1. A work vehicle including a front body having a pair of left and right wheels, a rear body connected to the front body so as to be rotatable in the left and right direction and having a pair of left and right wheels, and a work implement provided in front of the front body, wherein the front body and the rear body are provided so as to be bendable, an obstacle detection device that detects the position and shape of an obstacle present around the work vehicle; A control device is provided for controlling the bending angles of the front vehicle body and the rear vehicle body, The control device includes: calculating a maximum vehicle body occupancy area, which is an area occupied by the work vehicle, according to a change in the bending angle of the front vehicle body and the rear vehicle body; When it is determined that the obstacle is present in the maximum vehicle body occupancy area, A work vehicle characterized in that the distance between the work vehicle and the obstacle is calculated based on the detection result detected by the obstacle detection device, a limit value of the bending angle at which the work vehicle will not come into contact with the obstacle is calculated based on the calculated distance, and the bending angle of the front body and the rear body is controlled so as not to exceed the limit value.

2. 2. The work vehicle according to claim 1, The control device includes: A work vehicle characterized in that, when controlling the bending angle of the front body and the rear body so that the work vehicle travels along a predetermined travel path, the bending angle is controlled so as not to exceed the limit value.

3. 2. The work vehicle according to claim 1, The control device includes: Calculate the future predicted driving trajectory from the current bending angle, Calculating an expected distance between the work vehicle and the obstacle based on the detection result from the obstacle detection device and the predicted travel trajectory; calculating a limit value of the bending angle at which the work vehicle will not come into contact with the obstacle when traveling along the predicted travel trajectory based on the predicted distance; A work vehicle characterized in that the bending angle is controlled so as not to exceed the limit value.

4. The work vehicle according to claim 2 or 3, A work vehicle characterized in that the control device acquires information on the position and shape of obstacles contained in a surrounding map that is created in advance for the area around the work vehicle.

5. The work vehicle according to claim 2 or 3, A work vehicle characterized in that the control device acquires information on the position and shape of an obstacle based on information on the position and attitude of another work vehicle transmitted from the other work vehicle located in the vicinity of the work vehicle.

6. The work vehicle according to claim 2 or 3, A work vehicle characterized in that the control device calculates a distance between the work vehicle and the obstacle based on attitude information of a work implement of the work vehicle.

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