JP7714482B2 - Work vehicles - Google Patents

Description

This disclosure relates to a work vehicle.

A collision mitigation system and method for a work vehicle have been known for some time (see Patent Document 1 below). The articulated work vehicle described in Patent Document 1 includes a front frame having a first pair of wheels, a rear frame having a second pair of wheels, a hitch that flexibly connects the front frame to the rear frame, and a powertrain configured to drive at least the second pair of wheels. The work vehicle also includes a steering system, the first sensor system, the second sensor system, and a third sensor system, and a real-time processing circuit (see claim 1, etc.).

The steering system is configured to provide controlled articulation of the front frame relative to the rear frame about the hitch based on driver control input. The first sensor system is configured to detect objects around the articulated work vehicle. The second sensor system is configured to detect real-time articulation angles of the front frame relative to the rear frame. The third sensor system is configured to sense real-time rotation of the first and second wheel pairs.

The real-time processing circuit is electrically connected to the steering system, the first sensor system, the second sensor system, and the third sensor system. The real-time processing circuit also determines a safety zone around the articulated work vehicle based on signals from the first sensor system corresponding to detected objects around the articulated work vehicle.

The real-time processing circuit also determines the position and velocity of one or more peripheral points on the articulated work vehicle based on signals from the second sensor system and the third sensor system. The real-time processing circuit also receives driver control inputs and applies limits to the driver control inputs when the peripheral points of the articulated work vehicle are expected to be within a predetermined distance to the nearest edge of the safety zone.

Australian Patent Application Publication No. 2017276186

Patent Document 1, cited above, gives examples of the first sensor system, such as a 360-degree camera or multiple cameras sufficient to provide a 360-degree panoramic view (paragraph 0024). However, in a work vehicle, the blind spot of the sensor system may change due to, for example, the movement of a work implement attached to the front frame or the front frame bending relative to the rear frame, which may result in the work vehicle being unable to detect an object that needs to be avoided on the travel route.

This disclosure provides a work vehicle that can more reliably detect objects to be avoided along its travel route.

One aspect of the present disclosure is a work vehicle comprising: a front frame having a pair of front wheels; a rear frame having a pair of rear wheels; a connecting pin that flexibly connects the front frame to the rear frame; a drive unit that drives at least the pair of rear wheels; a steering unit that bends the front frame relative to the rear frame around the connecting pin; a work machine attached to the front frame; first external sensors that are provided on the front frame so as to be positioned on both sides of the work machine and that detect the position of an object to be avoided if the object is present in a predetermined area in front of the front frame through which the pair of front wheels are about to pass; a second external sensor that is attached to the rear frame at a position higher than the first external sensor and that detects at least the size of the object to be avoided detected by the first external sensor; a detection direction adjustment device that adjusts the detection direction of the second external sensor to the direction of the object to be avoided based on the position of the object to be avoided detected by the first external sensor; and a control device that controls the operation of at least one of the drive unit or the steering unit based on the size of the object to be avoided detected by the second external sensor based on the detection direction adjusted by the detection direction adjustment device.

The above aspect of the present disclosure makes it possible to provide a work vehicle that can more reliably detect objects to be avoided on its travel route.

1 is a side view showing an embodiment of a work vehicle according to the present disclosure. FIG. 2 is a block diagram of the work vehicle of FIG. 1 . FIG. 3 is a flow diagram illustrating the operation of the work vehicle of FIGS. 1 and 2 . FIG. 3 is a plan view illustrating the operation of the work vehicle of FIGS. 1 and 2 . 3 is a conceptual diagram illustrating the operation of a second external sensor of the work vehicle of FIG. 1 and FIG. 2 .

Embodiments of a work vehicle according to the present disclosure will be described below with reference to the drawings.

Figure 1 is a side view showing one embodiment of a work vehicle according to the present disclosure. Figure 2 is a block diagram of the work vehicle 100 of Figure 1. In the following description, each part of the work vehicle 100 may be described based on an orthogonal coordinate system consisting of an X axis parallel to the fore-and-aft direction of the work vehicle 100, a Y axis parallel to the width direction of the work vehicle 100, and a Z axis parallel to the height direction of the work vehicle 100.

The work vehicle 100 of this embodiment is a wheel loader that performs predetermined tasks at various work sites, such as mining areas, reclaimed land, quarries, and construction sites. The predetermined tasks performed by the work vehicle 100 include, for example, leveling work, excavation work, slope formation work, transporting soil, sand, crushed stone, minerals, etc., and loading work. Note that the work vehicle 100 is not limited to a wheel loader and may be another type of work vehicle.

The work vehicle 100 includes, for example, a front frame 111, a rear frame 112, a connecting pin 113, a drive unit 114, a steering unit 115, a work implement 120, a first external sensor 131, a second external sensor 132, a detection direction adjustment unit 133, and a control unit 140. The work vehicle 100 also includes, for example, a vehicle state sensor 134, an operating unit 135, a braking unit 116, and an alarm unit 117.

The front frame 111 has a pair of front wheels 118, and the rear frame 112 has a pair of rear wheels 119. The connecting pin 113 flexibly connects the front frame 111 to the rear frame 112. The front frame 111, rear frame 112, and connecting pin 113 form the body 110 of the work vehicle 100.

The drive unit 114 may, for example, include an engine mounted on the rear frame 112 and a hydrostatic continuously variable transmission (HST), and drive at least a pair of rear wheels 119. The drive unit 114 may also, for example, drive a pair of front wheels 118. The drive unit 114 may, for example, include a hydraulic system, and drive the steering system 115 and work implement 120, which will be described later. The hydraulic system of the drive unit 114 may, for example, be configured to generate braking force for the brake system 116.

The steering device 115 bends the front frame 111 relative to the rear frame 112 around the connecting pin 113. The steering device 115 has, for example, a pair of steering cylinders driven by a drive unit 114. Each steering cylinder has a piston rod and cylinder tube connected to the front frame 111 and rear frame 112, respectively, and by extending and retracting the piston rod, the front frame 111 bends relative to the rear frame 112 around the connecting pin 113.

The braking device 116 applies braking force to the pair of front wheels 118 and the pair of rear wheels 119, for example, based on a control signal from the control device 140 in response to operation of a brake pedal included in the operating device 135, thereby slowing down or stopping the work vehicle 100. The alarm device 117 is installed, for example, in the cabin 112a of the rear frame 112, and notifies the operator of the work vehicle 100 of information related to the work vehicle 100. The alarm device 117 includes, for example, a display device, indicator lamps, a speaker, an alarm, a buzzer, gauges, etc.

The work implement 120 is attached to the front frame 111 and extends forward of the work vehicle 100. The work implement 120 includes, for example, a pair of left and right lift arms 121, a bucket 122, a bell crank 123, and a bucket link 124. The work implement 120 also includes, for example, a lift arm cylinder 125 and a bucket cylinder 126.

The lift arm 121 is rotatably attached to the front frame 111 of the vehicle body 110. The longitudinal center of the lift arm 121 is rotatably connected to the tip of the piston rod of the lift arm cylinder 125. The base end of the cylinder tube opposite the piston rod of the lift arm cylinder 125 is rotatably connected to the front frame 111. The lift arm cylinder 125 is driven by the drive unit 114 to extend and retract, thereby rotating the lift arm 121 of the work machine 120 up and down.

The bucket 122 is rotatably attached to the tip end of the lift arm 121, which is attached to the vehicle body 110, opposite the base end. One end of the bucket link 124 is rotatably connected to the bottom of the bucket 122, and the other end of the bucket link 124 is rotatably connected to one end of the bell crank 123.

The longitudinal center of the bell crank 123 is rotatably connected, for example, to a support portion extending from a connecting portion connecting the pair of left and right lift arms 121 toward the bucket 122. The end of the bell crank 123 opposite the one end connected to the bucket link 124 is rotatably connected to the tip of the piston rod of the bucket cylinder 126.

The base end of the cylinder tube of the bucket cylinder 126, opposite the piston rod, is rotatably connected to the front frame 111. The bucket cylinder 126 is driven by the drive unit 114 to extend and retract, thereby rotating the bucket 122 up and down via the bell crank 123 and bucket link 124.

The first external sensors 131 are arranged on both sides of the work implement 120 on the front frame 111, and detect the position of at least the avoidance target AO in a predetermined area DA1 through which the pair of front wheels 118 in front of the front frame 111 pass (see Figure 4). In the example shown in Figures 1 and 4, the first external sensors 131 are fixed, for example, to the upper side of the headlights 111a that protrude outward in the width direction from the side of the front frame 111. Note that the first external sensors 131 may also be fixed, for example, to a bracket that protrudes outward in the width direction from the side of the front frame 111, separate from the headlights 111a.

The first external sensor 131 may be, for example, a millimeter-wave radar, laser radar, monocular camera, or stereo camera. The predetermined area DA1 in which the first external sensor 131 detects the position of the object to be avoided AO depends on the type of sensor, but includes at least the area through which the pair of front wheels 118 pass when the work vehicle 100 travels straight. The object to be avoided AO detected by the first external sensor 131 is, for example, an obstacle that could reduce the stability of the work vehicle 100, and includes uneven ground, rocks, fallen objects, trees, pedestrians, animals, vehicles, machinery, and other objects.

The first external sensor 131 detects at least the position of the object to be avoided AO. Specifically, the first external sensor 131 detects, for example, the distance, direction, size, type, etc. of an object present in the predetermined area DA1, and calculates the position of the object to be avoided AO. The first external sensor 131 is connected to the control device 140 via a wireless communication line or a wired communication line, and outputs the detection results of objects in the predetermined area DA1 to the control device 140.

The second external sensor 132 is attached to the rear frame 112 at a higher position than the first external sensor 131, and detects at least the size of the avoidance target AO detected by the first external sensor 131. The second external sensor 132 is attached, for example, to the center of the width of the upper front side of the cabin 112a provided on the rear frame 112. As with the first external sensor 131, the second external sensor 132 can be, for example, a millimeter-wave radar, laser radar, monocular camera, or stereo camera, or a combination of these may be used.

The detection direction adjustment device 133 readjusts the detection direction of the second external sensor 132 toward the avoidance target AO based on the position of the avoidance target AO detected by the first external sensor 131. The detection direction adjustment device 133 is composed of, for example, a motor, gears, angle sensor, etc. built into the second external sensor 132. The detection direction adjustment device 133 changes the detection direction of the second external sensor 132, for example, by rotating the sensing unit of the second external sensor 132 around a rotation axis parallel to the height direction of the work vehicle 100 or a rotation axis parallel to the width direction of the work vehicle 100. For example, if the second external sensor 132 is a monocular camera, the detection direction adjustment device 133 readjusts the detection direction so that the avoidance target AO captured by the monocular camera is at the center of the detected image.

The vehicle condition sensor 134 detects vehicle information including the speed of the work vehicle 100 and the tilt angle of the front frame 111 relative to the rear frame 112, and outputs the detected vehicle information to the control device 140. The vehicle condition sensor 134 includes at least a speed sensor that detects the speed of the work vehicle 100, and an angle sensor that detects vehicle information including the tilt angle of the front frame 111 relative to the rear frame 112.

The vehicle condition sensor 134 may also include at least one of an acceleration sensor, a Global Navigation Satellite System (GNSS) receiver, an engine rotation sensor, or an attitude sensor for the work implement 120. In this case, in addition to the speed and tilt angle of the work vehicle 100, the vehicle condition sensor 134 detects, for example, at least one of the acceleration, position, engine rotation speed, or attitude of the work vehicle 100. Note that the attitude sensor for the work implement 120 may be an angle sensor provided in the joint of the work implement 120, or a stroke sensor for the lift arm cylinder 125 and bucket cylinder 126.

The operating device 135 is installed, for example, inside the cabin 112a of the rear frame 112, accepts operations by the operator of the work vehicle 100, and outputs an operating signal corresponding to that operation to the control device 140. The operating device 135 includes, for example, at least one of an accelerator pedal, a brake pedal, or other operating pedal, a steering wheel, an operating lever, an operating switch, an operating button, a touch panel, or a voice recognition device.

The control device 140 controls the operation of the aforementioned drive device 114, steering device 115, and detection direction adjustment device 133. The control device 140 is, for example, an electronic control unit (ECU) installed below or at the rear of the cabin 112a in which the operator sits on the rear frame 112, and is composed of one or more microcontrollers. The microcontroller is composed of, for example, an input/output device, a central processing unit (CPU), memory, and a timer.

The control device 140 includes, for example, an avoidance target extraction unit 141, an avoidance area calculation unit 142, and a detection direction calculation unit 143. The control device 140 also includes, for example, a sensor diagnosis unit 144, a vehicle state acquisition unit 145, a stability calculation unit 146, an operation mode acquisition unit 147, an operation determination unit 148, and an operation control unit 149.

The parts of the control device 140 shown in Figure 2 are functional blocks representing various functions of the control device 140. Each function of the control device 140 is realized, for example, by the CPU of the control device 140 executing various programs stored in memory. Note that each function of the control device 140 can be realized by a single ECU, and multiple functions can also be realized by a single ECU.

The operation of the work vehicle 100 of this embodiment will be described below. Figure 3 is a flow diagram explaining the operation of the work vehicle 100 of Figures 1 and 2. Figure 4 is a plan view explaining the operation of the work vehicle 100 of Figures 1 and 2.

For example, when the work vehicle 100 starts traveling, the control device 140 starts the processing flow shown in Figure 3. When the control device 140 starts the processing flow shown in Figure 3, it first executes process P1, which acquires first external environment information. In process P1, the avoidance target extraction unit 141 of the control device 140 shown in Figure 2 acquires first external environment information D1 output from first external environment sensors 131 attached to both sides of the work implement 120 on the front frame 111.

As shown in FIG. 4, the first external sensor 131 detects the positions of objects in a predetermined area DA1 that includes at least the area through which the pair of front wheels 118 at the front of the work vehicle 100 passes while in motion, and outputs this to the control device 140. Specifically, the first external sensor 131, for example, detects the distance and direction of objects in the predetermined area DA1, calculates the relative positions of the objects in the predetermined area DA1, and outputs this to the control device 140. The avoidance target extraction unit 141 acquires the positions of objects in the predetermined area DA1 output from the first external sensor 131 as first external information D1.

The first external sensor 131 may also detect the size, shape, and type of objects present in the predetermined area DA1. In the example shown in FIG. 4, the first external sensor 131 detects, for example, the ground, unevenness, rocks, fallen objects, trees, pedestrians (including workers working around the vehicle), animals, vehicles, machinery, and other objects present in the predetermined area DA1, and outputs the size, shape, and type of the detected objects to the control device 140. In this case, the avoidance target extraction unit 141 acquires, for example, the position, size, shape, and type of objects in the predetermined area DA1 output from the first external sensor 131 as first external information D1.

Next, the control device 140 executes process P2, for example, to extract an avoidance target AO. In process P2, the avoidance target extraction unit 141 of the control device 140 extracts an avoidance target AO that the work vehicle 100 should avoid from the first external environment information D1 acquired in process P1. In this process P2, the avoidance target extraction unit 141 functions, for example, as a selector, filter, and sampler that extracts an avoidance target AO from the first external environment information D1.

In process P2, the avoidance target extraction unit 141 extracts, for example, an object to be avoided AO that is located at a position where the pair of front wheels 118 are predicted to pass and that is closer than a predetermined distance, based on the position of the object included in the first external environment information D1. In process P2, the avoidance target extraction unit 141 may also calculate, for example, the height from the ground of an object included in the first external environment information D1, and extract, as an avoidance target AO, an object whose calculated height is equal to or greater than a predetermined threshold value.

Furthermore, in process P2, the avoidance target extraction unit 141 may extract an avoidance target AO based on the size and shape of the object included in the first external environment information D1, in addition to the height of the object. The avoidance target extraction unit 141 outputs information D2 on the extracted avoidance target AO to, for example, the avoidance area calculation unit 142 and the stability calculation unit 146.

Next, the control device 140 executes process P3 to determine whether or not there is an AO to be avoided. In process P3, the avoidance area calculation unit 142 and the stability calculation unit 146 determine that there is an AO to be avoided (YES) if information D2 is input from the avoidance target extraction unit 141, and determine that there is no AO to be avoided (NO) if information D2 is not input.

When the control device 140 determines in process P3 that an avoidance target AO is present (YES), it executes process P4, which calculates an avoidance area and stability. In process P4, the avoidance area calculation unit 142 calculates an avoidance area including the avoidance target AO based on information D2 about the avoidance target AO input from the avoidance target extraction unit 141. The avoidance area is, for example, an area that includes the position of the avoidance target AO and the range where the distance from the avoidance target AO is less than a predetermined threshold, and is an area in which the avoidance target AO exists. The avoidance area calculation unit 142 outputs information D3 about the calculated avoidance area to, for example, the detection direction calculation unit 143 and the operation determination unit 148.

Furthermore, in process P4, the stability calculation unit 146 calculates the stability when the work vehicle 100 passes over the avoidance target AO based on the information D2 of the avoidance target AO input from the avoidance target extraction unit 141. The stability calculation unit 146 calculates the stability of the work vehicle 100 based on, for example, the information D2 of the avoidance target AO and vehicle information D5 including the speed of the work vehicle 100 input from the vehicle state acquisition unit 145. Here, the vehicle state acquisition unit 145, for example, acquires a detection signal D4 from the vehicle state sensor 134, calculates vehicle information D5 including the speed of the work vehicle 100 based on the detection signal D4, and outputs it to the stability calculation unit 146.

The stability calculation unit 146 calculates the stability of the work vehicle 100 according to, for example, the height of the avoidance target AO from the ground. Specifically, the stability of the work vehicle 100 calculated by the stability calculation unit 146 decreases as the height of the avoidance target AO from the ground increases, and increases as the height of the avoidance target AO from the ground decreases. The stability calculation unit 146 also calculates the stability of the work vehicle 100 according to, for example, the speed of the work vehicle 100. Specifically, the stability of the work vehicle 100 calculated by the stability calculation unit 146 decreases as the speed of the work vehicle 100 increases, and increases as the speed of the work vehicle 100 decreases.

The stability calculation unit 146 may also calculate the stability of the work vehicle 100 based on both the height of the avoidance target AO from the ground and the speed of the work vehicle 100. The stability calculation unit 146 may also calculate the stability of the work vehicle 100 based on the size and shape of the avoidance target AO. The stability calculation unit 146 outputs the calculated stability D6 of the work vehicle 100 to the operation determination unit 148.

Next, the control device 140 executes process P5 to calculate the detection direction of the second external sensor 132. In process P5, the detection direction calculation unit 143 calculates the angle of the detection direction of the second external sensor 132, for example, based on the avoidance area information D3 acquired from the avoidance area calculation unit 142.

Figure 5 is a conceptual diagram illustrating the operation of the second external sensor 132 of the work vehicle 100 of Figures 1 and 2. In process P5 for calculating the detection direction of the second external sensor 132, the detection direction calculation unit 143 calculates the height H from the ground G to the second external sensor 132 based on, for example, information about the mounting position of the second external sensor 132 stored in the non-volatile memory of the control device 140.

Furthermore, the detection direction calculation unit 143 calculates angles θ1, θ2, and θ3 of the second external sensor 132 to readjust the detection direction of the second external sensor 132 to each avoidance area, based on information D3 of the avoidance area including the avoidance target AO obtained from the avoidance area calculation unit 142. In the example shown in FIG. 5, if multiple avoidance targets AO are detected by the first external sensor 131, the detection direction calculation unit 143 calculates angles θ1, θ2, and θ3 sequentially, starting from the detection area closest to the work vehicle 100.

Note that Figure 5 shows angles θ1, θ2, and θ3 of the detection direction of the second external sensor 132 relative to the height direction (Z-axis direction) of the work vehicle 100. However, in process P5, the detection direction calculation unit 143 can similarly calculate, for example, the angle of the detection direction of the second external sensor 132 relative to the fore-and-aft direction (X-axis direction) of the work vehicle 100. The detection direction calculation unit 143 outputs the calculated angle D7 of the detection direction of the second external sensor 132 to the operation determination unit 148.

Next, the control device 140 executes process P6 to acquire second external environment information D9 from the second external environment sensor 132. In this process P6, the operation determination unit 148 calculates the rotation angle of the second external environment sensor 132 by the detection direction adjustment device 133, for example, based on the angle D7 of the detection direction of the second external environment sensor 132 acquired from the detection direction calculation unit 143. Furthermore, the operation determination unit 148 outputs the calculated rotation angle of the second external environment sensor 132 to the operation control unit 149 as operation information D8.

The operation control unit 149 outputs a control signal to the detection direction adjustment device 133 based on the rotation angle of the second external sensor 132, which is operation information D8 input from the operation determination unit 148, and controls the operation of the detection direction adjustment device 133. As a result, the detection direction adjustment device 133 readjusts the detection direction of the second external sensor 132 to an avoidance area including the avoidance target AO, as shown in FIG. 5. The avoidance target extraction unit 141 then acquires the second external information D9 output from the second external sensor 132.

As shown in FIG. 4, the second external sensor 132 is attached to the upper part of the cabin 112a of the rear frame 112, and detects the size of the avoidance target AO detected by the first external sensor 131 in a predetermined area DA2 in front of the work vehicle 100. Note that the second external sensor 132 may detect not only the size of the avoidance target AO, but also the distance and direction from the second external sensor 132 to the avoidance target AO, the type of the avoidance target AO, etc.

The predetermined area DA2 in which the second external sensor 132 detects the target to be avoided AO is, for example, wider in the width direction of the work vehicle 100 than the predetermined area DA1 in which the first external sensor 131 detects the target to be avoided AO. Note that the width of the predetermined area DA2 in which the second external sensor 132 detects the target to be avoided AO in the longitudinal direction of the work vehicle 100 changes as shown in Figure 4 by changing the detection direction using the detection direction adjustment device 133.

In other words, the second external sensor 132 is a dynamic sensor in which the predetermined area DA2 for detecting the avoidance target AO changes depending on the operation of the detection direction adjustment device 133. Furthermore, the avoidance target AO detected by the second external sensor 132 has various sizes and shapes, such as wide and narrow avoidance target AO, and includes moving objects that suddenly appear in the area through which the front wheels 118 of the work vehicle 100 pass.

Next, the control device 140 executes process P7 to determine whether or not an avoidance target AO is present on the travel path of the work vehicle 100. In process P7, the avoidance target extraction unit 141 extracts an avoidance target AO that the work vehicle 100 should avoid, based on the second external environment information D9 acquired from the second external environment sensor 132. For example, the avoidance target extraction unit 141 extracts an avoidance target AO that exceeds a predetermined threshold value for height, width, depth, etc., and outputs information D2 on the extracted avoidance target AO to the stability calculation unit 146.

The vehicle state acquisition unit 145 also calculates vehicle information D5 based on the detection signal D4 acquired from the vehicle state sensor 134 and outputs the information to the stability calculation unit 146. The stability calculation unit 146 determines whether an avoidance target AO is present on the travel route of the work vehicle 100 based on the vehicle information D5 input from the vehicle state acquisition unit 145 and the information D2 on the avoidance target AO input from the avoidance target extraction unit 141.

When the stability calculation unit 146 determines that no avoidance target AO exists on the travel path of the work vehicle 100 (Process P7: NO), the control device 140 again executes Process P1 to acquire the above-mentioned first external environment information D1. Furthermore, when the stability calculation unit 146 determines that an avoidance target AO exists on the travel path of the work vehicle 100 (Process P7: YES), the control device 140 executes Process P11 to determine the operation of the work vehicle 100.

On the other hand, in the above-mentioned process P3, if the first external environment information D1 from the first external environment sensor 131 does not include an avoidance target AO and information D2 about the avoidance target AO is not input from the avoidance target extraction unit 141 to the avoidance area calculation unit 142, etc., the control device 140 determines that there is no avoidance target AO (NO). In this case, the control device 140 executes process P8 to acquire second external environment information.

In this process P8, the operation determination unit 148 outputs operation information D8 to stop the detection direction adjustment device 133 at a predetermined position. Based on the operation information D8 input from the operation determination unit 148, the operation control unit 149 stops the detection direction adjustment device 133 at a specified position and readjusts the detection direction of the second external sensor 132 to a specified direction. This specified direction may be changed depending on the speed and stopping distance of the work vehicle 100, for example, so that the faster the speed of the work vehicle 100, the more distant the avoidance target AO will be detected. The avoidance target extraction unit 141 acquires second external environment information D9 from the second external environment sensor 132.

Next, the control device 140 executes process P9 to determine whether or not there is an avoidance target. In process P9, the avoidance target extraction unit 141 extracts an avoidance target AO from the second external environment information D9 acquired from the second external environment sensor 132. More specifically, in process P9, the avoidance target extraction unit 141 executes, for example, the same process as that performed on the first external environment information D1 from the first external environment sensor 131 in the above-mentioned process P2 on the second external environment information D9 from the second external environment sensor 132. The avoidance target extraction unit 141 outputs information D2 of the extracted avoidance target AO to, for example, the avoidance area calculation unit 142 and the stability calculation unit 146.

In this process P9, similar to the process P3 described above, the avoidance area calculation unit 142 and the stability calculation unit 146 determine that an avoidance target AO exists (YES) if information D2 is input from the avoidance area calculation unit 142, and determine that an avoidance target AO does not exist (NO) if information D2 is not input. In this process P9, if the avoidance area calculation unit 142 and the stability calculation unit 146 determine that an avoidance target AO does not exist (NO), the control device 140 returns to process P1, which acquires the first external environment information D1 described above.

On the other hand, if the avoidance area calculation unit 142 and the stability calculation unit 146 determine in process P9 that an avoidance target AO exists (YES), they execute process P10, similar to process P4 described above, to calculate the avoidance area including the avoidance target AO and the stability of the work vehicle 100 passing through the avoidance target AO. The control device 140 then executes process P11 to determine the operation of the drive device 114, steering device 115, braking device 116, and alarm device 117.

In process P11 for determining the operation of the work vehicle 100, the stability calculation unit 146 calculates the stability D6 of the work vehicle 100 based on, for example, vehicle information D5 and information D2 about the avoidance target AO, and outputs the calculated stability D6 to the operation determination unit 148. Furthermore, the operation device 135 outputs, for example, an operation signal D10 based on the operation of the operator of the work vehicle 100 to the operation mode acquisition unit 147 and the operation determination unit 148. The operation mode acquisition unit 147 acquires the operation mode D11 of the work vehicle 100 based on the vehicle information D5 acquired from the vehicle state acquisition unit 145 and the operation signal D10 input from the operation device 135.

Here, the operation mode D11 of the work vehicle 100 includes control modes of the work vehicle 100, such as manual operation mode, automatic control mode, and semi-automatic control mode. The operation mode D11 of the work vehicle 100 also includes information regarding the work mode currently being performed by the work vehicle 100, such as traveling mode, excavation mode, leveling mode, and loading mode. The operation mode acquisition unit 147 determines the operation mode D11 based on, for example, the operation of an operation switch, operation lever, operation pedal, etc. included in the operation device 135.

Furthermore, in this process P11, the operation determination unit 148 determines the operation of the work vehicle 100, for example, based on the stability D6 input from the stability calculation unit 146 and the operation mode D11 input from the operation mode acquisition unit 147. More specifically, when the stability D6 of the work vehicle 100 is lower than a predetermined threshold, the operation determination unit 148 determines an avoidance operation to avoid the avoidance area including the avoidance target AO by controlling at least one of the drive device 114, steering device 115, or braking device 116. In this case, the operation determination unit 148 may further determine an alarm operation to control the alarm device 117 to notify the operator of the work vehicle 100 of the avoidance operation.

Here, the avoidance actions of the drive device 114, steering device 115, or braking device 116 include, for example, actions such as decelerating, stopping, turning, or changing the travel route of the work vehicle 100, or limiting the input of the operation signal D10 based on the operator's operation of the operation device 135. Furthermore, the notification actions of the notification device 117 include, for example, actions such as displaying on an image display device, providing audio guidance through a speaker, sounding a buzzer or alarm, or turning on an indicator lamp, targeting at least one of the stability, avoidance area, avoidance target AO, or avoidance action of the work vehicle 100.

Furthermore, for example, when the stability D6 of the work vehicle 100 is equal to or greater than a predetermined threshold, the operation determination unit 148 determines the operation of the drive unit 114, steering unit 115, braking unit 116, and alarm device 117 in accordance with the operation mode D11 input from the operation mode acquisition unit 147. Specifically, for example, when the operation mode D11 is a manual operation mode, the operation determination unit 148 determines the operation of the drive unit 114, steering unit 115, braking unit 116, and alarm device 117 based on an operation signal D10 in response to operation of the operation device 135 by the operator of the work vehicle 100. Furthermore, when the operation mode D11 is an automatic control mode or a semi-automatic control mode, the operation determination unit 148 autonomously determines the operation of the drive unit 114, steering unit 115, braking unit 116, and alarm device 117.

Next, the control device 140 executes process P12 to diagnose the sensors. In process P12, the sensor diagnostic unit 144 diagnoses the first external sensor 131 and the second external sensor 132 based on the first external environment information D1 input from the first external environment sensor 131 and the second external environment information D9 input from the second external environment sensor 132. Specifically, the sensor diagnostic unit 144 diagnoses the reliability of the first external environment information D1 and the second external environment information D9, as well as the reliability of the data interface. The sensor diagnostic unit 144 outputs the diagnosis result D12 to the operation determination unit 148.

Next, the control device 140 executes process P13 to diagnose the operation of the work vehicle 100. In this process P13, the operation determination unit 148 diagnoses the operation of the work vehicle 100 determined in the above-mentioned process P11 based on the diagnosis result D12 input from the sensor diagnosis unit 144. For example, if there is a problem with the diagnosis result D12 of the first external sensor 131 and the second external sensor 132, the operation determination unit 148 changes the operation determined in the above-mentioned process P11, determines an emergency operation such as an emergency stop, and outputs this as operation information D8 to the operation control unit 149. If there is no problem with the diagnosis result D12, the operation determination unit 148 maintains the operation determined in the above-mentioned process P11 and outputs it to the operation control unit 149 as operation information D8.

Next, the control device 140 performs process P14 to execute the operation of the work vehicle 100 determined by the operation determination unit 148. In this process P14, the operation control unit 149 outputs control signals corresponding to the operation information D8 input from the operation determination unit 148 to the drive device 114, steering device 115, braking device 116, and alarm device 117. This allows the work vehicle 100 to perform avoidance operations to avoid the avoidance area including the avoidance target AO, alarm operations to notify the operator of the avoidance operation, and emergency operations when the reliability of the first external sensor 131 and the second external sensor 132 decreases.

Furthermore, while it is determined in the above-mentioned process P7 or process P9 that there is no AO to be avoided (NO), the operation determination unit 148 determines an operation in accordance with the operation signal D10 based on the operator's operation of the operation device 135, and outputs this as operation information D8 to the operation control unit 149. Therefore, when there is no AO to be avoided on the travel path of the work vehicle 100, the control device 140 controls the drive device 114, steering device 115, braking device 116, and alarm device 117 in accordance with the operator's operation of the operation device 135.

The control device 140 may also monitor the operation of the avoidance target extraction unit 141, which functions as a selector, filter, and sampler. If the avoidance target extraction unit 141 is not operating normally due to some malfunction, the operation determination unit 148 determines an operation to display the malfunction on the alarm device 117 and outputs operation information D8, and the operation control unit 149 displays the malfunction on the alarm device 117 based on the input operation information D8.

As is clear from the above description, the work vehicle 100 of this embodiment is characterized by the following configuration. The work vehicle 100 comprises a front frame 111 having a pair of front wheels 118, a rear frame 112 having a pair of rear wheels 119, and a connecting pin 113 that flexibly connects the front frame 111 to the rear frame 112. The work vehicle 100 also comprises a drive unit 114 that drives at least the pair of rear wheels 119, a steering unit 115 that flexes the front frame 111 relative to the rear frame 112 about the connecting pin 113, and a work implement 120 attached to the front frame 111. The work vehicle 100 also comprises a first external sensor 131, a second external sensor 132, a detection direction adjustment device 133, and a control device 140. The first external sensors 131 are mounted on the front frame 111 so as to be positioned on both sides of the work machine 120, and detect the position of an object to be avoided AO if it exists in a predetermined area DA1 in front of the front frame 111 through which the pair of front wheels 118 are about to pass. The second external sensor 132 is mounted on the rear frame 112 at a higher position than the first external sensor 131, and detects at least the size of the object to be avoided AO detected by the first external sensor 131. The detection direction adjustment device 133 adjusts the detection direction of the second external sensor 132 toward the object to be avoided AO based on the position of the object to be avoided AO detected by the first external sensor 131. The control device 140 controls the operation of at least one of the drive device 114 or the steering device 115 based on the detection direction adjusted by the detection direction adjustment device 133.

In this way, in the work vehicle 100 of this embodiment, the first external sensors 131 are arranged on both sides of the work implement 120 on the front frame 111, so the first external sensors 131 can detect objects in the specified area DA1 in front of the front frame 111 regardless of the attitude of the work implement 120. Therefore, for example, even if the work implement 120 rises and a blind spot appears in the specified area DA2 detected by the second external sensor 132, the first external sensor 131 can still detect an object to be avoided AO in front of the front frame 111.

Furthermore, if the front frame 111 bends relative to the rear frame 112 when the work vehicle 100 turns, an inclination angle occurs between the fore-and-aft direction of the front frame 111 and the fore-and-aft direction of the rear frame 112, which may result in a blind spot in the specified area DA2 detected by the second external sensor 132 attached to the rear frame 112. However, because the first external sensor 131 is attached to the front frame 111, even if the front frame 111 bends relative to the rear frame 112, no blind spot is created in the specified area DA1 through which the pair of front wheels 118 pass when the work vehicle 100 travels straight.

The second external sensor 132 is attached to the rear frame 112 at a higher position than the first external sensor 131, and the detection direction can be changed by the detection direction adjustment device 133 from a predetermined area DA2 near the work vehicle 100 to a predetermined area DA2 farther away. Therefore, the detection direction of the second external sensor 132 can be directed toward the position of the avoidance target AO detected by the first external sensor 131, allowing the size of the avoidance target AO to be reliably detected.

In this way, the work vehicle 100 can more reliably detect objects to be avoided AO on the travel path using the first external sensors 131 located on both sides of the work implement 120 on the front frame 111 and the second external sensor 132 attached to the rear frame 112 at a position higher than the first external sensor 131. As a result, the control device 140 can avoid the objects to be avoided AO by controlling the drive device 114 and steering device 115 according to the size of the objects to be avoided AO detected by the second external sensor 132.

Therefore, the work vehicle 100 of this embodiment can prevent a decrease in the stability of the work vehicle 100 caused by the work vehicle 100 performing a predetermined task at a work site in automatic control mode, semi-automatic control mode, or manual control mode passing over an avoidance target AO. In other words, the work vehicle 100 of this embodiment can achieve contextual awareness of objects around the work vehicle 100 and dynamically detect avoidance targets AO that affect the stability of the work vehicle 100.

In addition, in the work vehicle 100 of this embodiment, the control device 140 is equipped with an avoidance target extraction unit 141, an avoidance area calculation unit 142, and a detection direction calculation unit 143. The avoidance target extraction unit 141 extracts an avoidance target AO based on information acquired from at least one of the first external sensor 131 and the second external sensor 132. The avoidance area calculation unit 142 calculates the avoidance area in which the avoidance target AO exists based on the position of the extracted avoidance target AO. The detection direction calculation unit 143 calculates the angles θ1, θ2, and θ3 of the detection direction of the second external sensor 132 based on the avoidance area.

With this configuration, the work vehicle 100 of this embodiment can identify an avoidance area that includes the avoidance target AO detected by the first external sensor 131, direct the detection direction of the second external sensor 132 toward that avoidance area, and detect the size of the avoidance target AO using the second external sensor 132. Therefore, the work vehicle 100 of this embodiment can more reliably detect the avoidance target AO on the travel route.

The work vehicle 100 of this embodiment is further equipped with a braking device 116 that brakes at least one of the pair of front wheels 118 and the pair of rear wheels 119. The control device 140 is also equipped with a stability calculation unit 146 and an operation determination unit 148. The stability calculation unit 146 calculates the stability of the work vehicle 100 based on the size of the avoidance target AO. If the stability calculated by the stability calculation unit 146 is lower than a predetermined threshold, the operation determination unit 148 determines an avoidance operation to avoid the avoidance area by controlling at least one of the drive device 114, steering device 115, or braking device 116.

With this configuration, the work vehicle 100 of this embodiment can execute avoidance operations to avoid the avoidance area containing the avoidance target AO under the control of the control device 140 when the avoidance target AO affects the stability of the work vehicle 100. Therefore, with the work vehicle 100 of this embodiment, it is possible to prevent a decrease in stability due to the avoidance target AO on the travel route detected by the first external sensor 131 and the second external sensor 132.

The above has described in detail an embodiment of a work vehicle according to the present disclosure using the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present disclosure are also included in the present disclosure. For example, part of the configuration of the control device 140, including the avoidance target extraction unit 141, avoidance area calculation unit 142, and detection direction calculation unit 143, may be included in the first external sensor 131 or the second external sensor 132.

DESCRIPTION OF SYMBOLS 100 Work vehicle 111 Front frame 112 Rear frame 113 Connecting pin 114 Drive device 115 Steering device 116 Braking device 118 Front wheels 119 Rear wheels 120 Work machine 131 First external sensor 132 Second external sensor 133 Detection direction adjustment device 140 Control device 141 Avoidance target extraction unit 142 Avoidance area calculation unit 143 Detection direction calculation unit 146 Stability calculation unit 148 Operation determination unit AO Avoidance target DA1 Predetermined area

Claims (3)

a front frame having a pair of front wheels;
a rear frame having a pair of rear wheels;
a connecting pin that bendably connects the front frame to the rear frame;
a drive unit that drives at least the pair of rear wheels;
a steering device that bends the front frame relative to the rear frame around the connecting pin;
a work implement attached to the front frame; and
a first external sensor provided on a front frame so as to be positioned on both sides of the work machine, the first external sensor detecting the position of an object to be avoided when the object to be avoided exists in a predetermined area in front of the front frame that the pair of front wheels are about to pass through;
a second external sensor attached to the rear frame at a position higher than the first external sensor, the second external sensor detecting at least the size of the object to be avoided detected by the first external sensor;
a detection direction adjustment device that adjusts the detection direction of the second external sensor to the direction of the object to be avoided based on the position of the object to be avoided detected by the first external sensor;
a control device that controls the operation of at least one of the drive device and the steering device based on the size of the object to be avoided detected by the second external sensor based on the detection direction adjusted by the detection direction adjustment device;
A work vehicle comprising: The work vehicle described in claim 1, characterized in that the control device comprises an avoidance target extraction unit that extracts the avoidance target based on information acquired from at least one of the first external sensor and the second external sensor, an avoidance area calculation unit that calculates an avoidance area in which the avoidance target exists based on the position of the extracted avoidance target, and a detection direction calculation unit that calculates the angle of the detection direction of the second external sensor based on the avoidance area. a braking device that brakes at least one of the pair of front wheels and the pair of rear wheels,
3. The work vehicle according to claim 2, wherein the control device comprises: a stability calculation unit that calculates stability indicating the stability of the work vehicle's travel when the work vehicle passes over the object to be avoided based on the size of the object to be avoided; and an operation determination unit that determines an avoidance operation to avoid the avoidance area by controlling at least one of the drive device, the steering device, or the braking device when the stability is lower than a predetermined threshold value.