Transport vehicle

Abstract

To suppress decrease in estimation accuracy of an own vehicle position due to a height of a vehicle body.SOLUTION: A transport vehicle 1 comprises a load-carrying platform 3, and a vehicle body 2. Further, the transport vehicle 1 comprises: a distance meter 30 which measures a horizontal distance to an object; a linear actuator 20 which is attached to the vehicle body 2, and supports the distance meter 30 movably between a first position and a second position; a storage part which stores map data including corresponding object position data when the vehicle body 2 exists at a first reference height and the distance meter 30 exists at a prescribed height in a travel area of the transport vehicle 1; and an own vehicle position estimation part which estimates an own vehicle position on the basis of object detection position data based on distance data to the object measured by the distance meter 30 and object position data included in the map data.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a transporter having a body including a loading platform. [Background technology]

[0002] Examples of transport vehicles used to transport cargo include carrier pallet vehicles that are self-propelled and enter under pallets on which cargo is placed, then raise the loading platform to transport the pallets with the cargo on them.

[0003] In recent years, efforts have been made to streamline logistics by enabling unmanned operation and remote control of transport vehicles such as carrier pallet vehicles. Some unmanned automated guided vehicles include an autonomous driving control device and an approach guidance device (see Patent Document 1). The autonomous driving control device in this automated guided vehicle measures the current position of the automated guided vehicle based on map information of the travel route, a travel distance sensor, a gyroscope, and other current position recognition devices, and causes the automated guided vehicle to travel along a predetermined route. The approach guidance device then guides the automated guided vehicle to the vicinity of the pallet. The approach guidance device includes an approach sensor for detecting the horizontal distance to the pallet and guiding the automated guided vehicle to approach the pallet, and guides the automated guided vehicle until it picks up the pallet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-182744 Summary of the Invention [Problem to be solved by the invention]

[0005] In the automated guided vehicle described in Patent Document 1, although the autonomous driving control device can drive the automated guided vehicle along a preset route, it is not capable of guiding the vehicle to the object with high accuracy because it does not have a configuration for detecting the horizontal distance to the object. On the other hand, the approach guidance device can provide high-accuracy guidance to the object by detecting the distance to the object. By combining these devices, it is possible to detect the distance to an object such as an obstacle while driving, recognize the current position based on the object's position data in map information and the position data of the detected object, and drive the automated guided vehicle.

[0006] However, the running parts of an automated guided vehicle usually have multiple tires and shock absorbers to absorb impacts. Therefore, the height of the vehicle body of an automated guided vehicle changes depending on the weight of the cargo loaded on the vehicle body. In other words, the heavier the cargo, the more the vehicle body sinks, and the lower the vehicle height becomes. Furthermore, an automated guided vehicle supports cargo by raising the vehicle body, including the loading platform. Thus, the height of the vehicle body of an automated guided vehicle changes depending on the weight of the cargo and the conditions for raising the vehicle body when supporting the cargo. Therefore, the sensor (sensor that detects the horizontal distance to an object) fixed to the vehicle body also displaces depending on the height of the vehicle body. When the height of the sensor displaces depending on the height of the vehicle body, the horizontal distance to the object detected by the sensor changes if the horizontal cross-sectional shape of the object is not uniform along the vertical direction. In other words, if the height of the vehicle body differs before and after loading the cargo, depending on the weight of the cargo, and the amount of elevation of the vehicle body when supporting the cargo, when the position data of an object in the map information is position data for a specific height, there will be a discrepancy with the position data of the object based on the horizontal distance detected by the sensor, and the estimation accuracy of the vehicle's position relative to the object will decrease, resulting in a problem of reduced guidance accuracy for the automated guided vehicle.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a transporter that can suppress a decrease in the accuracy of estimating its own vehicle position due to the height of the vehicle body. [Means for solving the problem]

[0008] The transport vehicle of the present invention is a transport vehicle having a body including a loading platform, and is equipped with a rangefinder that measures the horizontal distance to an object, a support mechanism attached to the body and movably supporting the rangefinder between a first position and a second position higher than the first position, a memory unit that stores map data including position data of the object corresponding to when the body is at a reference height and the rangefinder is at a predetermined height in the travel area of ​​the transport vehicle, and a vehicle position estimation unit that estimates the vehicle position based on detected position data of the object based on the distance data to the object measured by the rangefinder and the position data of the object included in the map data.

[0009] This allows the support mechanism to move the rangefinder between the first position and the second position. Therefore, even if the vehicle body is displaced relative to the reference height, the height of the rangefinder can be adjusted to a predetermined height. Therefore, it is possible to suppress a decrease in the estimation accuracy of the vehicle's position caused by the height of the vehicle body. As a result, it is possible to maintain the guidance accuracy of the transport vehicle.

[0010] In the present invention, the vehicle may further include an elevation difference deriving means for deriving an elevation difference between the vehicle body when loaded with cargo and the vehicle body when unloaded and at the reference height, the support mechanism preferably having an actuator for moving the rangefinder, and the vehicle position estimating unit preferably drives the actuator so that the rangefinder is positioned at the predetermined height based on the elevation difference derived by the elevation difference deriving means when loaded with cargo. This makes it possible to position the rangefinder at the predetermined height even if the height of the vehicle body when loaded with cargo differs from the reference height of the vehicle body. This makes it possible to further suppress a decrease in the accuracy of estimating the vehicle position due to the height of the vehicle body.

[0011] In the present invention, it is also preferable that the elevation difference deriving means has a load detection unit that detects a load applied to the vehicle body when cargo is loaded, and derives the elevation difference based on the load detected by the load detection unit. This makes it possible to move the rangefinder based on the elevation difference derived based on the load.

[0012] In addition, in the present invention, it is preferable that the vehicle further includes a traveling unit capable of traveling while supporting the vehicle body, and the traveling unit has a lifting unit capable of raising and lowering the vehicle body to or above the reference height. This makes it possible to suppress a decrease in the estimation accuracy of the vehicle position due to the height of the vehicle body, even when the vehicle body is raised by the lifting unit to load cargo and the cargo is transported by a transport vehicle.

[0013] Furthermore, in the present invention, it is preferable that the second position is vertically above the first position, and the support mechanism moves the rangefinder in the vertical direction. This allows the rangefinder to be moved in the vertical direction, thereby minimizing the distance traveled by the rangefinder. Furthermore, when the rangefinder is moved between the first position and the second position, it does not shift horizontally. This makes it easier to derive detected position data of an object based on distance data to the object measured by the rangefinder. [Effects of the Invention]

[0014] According to the transporter of the present invention, the support mechanism allows the rangefinder to be moved between a first position and a second position. Therefore, even if the vehicle body is displaced relative to the reference height, the height of the rangefinder can be adjusted to a predetermined height. Therefore, it is possible to suppress a decrease in the estimation accuracy of the vehicle's position due to the height of the vehicle body. As a result, it is possible to maintain the guidance accuracy of the transporter. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic side view of a transporter according to an embodiment of the present invention. [Figure 2]2 is a perspective view of a linear actuator and a distance meter fixed to the body of the transporter shown in FIG. 1. FIG. [Figure 3] 2 is a block diagram showing the electrical configuration of a control unit of the transporter of FIG. 1. FIG. [Figure 4] FIG. 1 is a diagram showing a situation when measuring the distance to an object using a rangefinder. [Figure 5] FIG. 1 is a diagram showing a situation when cargo is loaded onto a transport vehicle. [Figure 6] 6(a) is a diagram showing the situation when cargo is loaded onto a transport vehicle, and FIG. 6(b) is a diagram showing the situation when the rangefinder shown in FIG. 6(a) is raised so that it is positioned at a predetermined height. [Figure 7] 7A and 7B show modified examples of a transporter when the amount of lift of the vehicle body when loading cargo is changed from a first predetermined amount to a second predetermined amount, where (a) is a diagram showing the situation when cargo is loaded onto the transporter, and (b) is a diagram showing the situation when the rangefinder shown in FIG. 7A is lowered so that it is positioned at a predetermined height. [Figure 8] 8A and 8B show modified examples of a transporter when the amount of lift of the vehicle body when loading cargo is changed from a first predetermined amount to a third predetermined amount, where (a) is a diagram showing the situation when cargo is loaded onto the transporter, and (b) is a diagram showing the situation when the rangefinder shown in FIG. 8A is lowered so that it is positioned at another predetermined height. DETAILED DESCRIPTION OF THE INVENTION

[0016] The configuration of a transporter 1 according to one embodiment of the present invention will be described below with reference to FIGS.

[0017] As shown in FIG. 1, the transport vehicle 1 is a carrier pallet vehicle, which is a type of transport vehicle used to transport heavy cargo. The transport vehicle 1 is not limited to a carrier pallet vehicle, and may be any other type of vehicle that travels with cargo loaded on its platform. The transport vehicle 1 also has an engine (not shown) as a prime mover that generates driving force. An electric motor may be used as a prime mover instead of or in addition to the engine.

[0018] 1 also shows the X, Y, and Z directions. The X direction is the traveling direction of the transport vehicle 1, and the Y direction is the width direction of the transport vehicle 1, which is perpendicular to the traveling direction (X direction). The Z direction is the up-down direction perpendicular to the horizontal XY plane. The same directions are also shown in FIGS. 2 and 4 to 6.

[0019] The transporter 1 comprises a vehicle body 2, a traveling unit 6 capable of traveling while supporting the vehicle body 2, and a control unit 7 (see FIG. 3). As shown in FIG. 1, the vehicle body 2 has a loading platform 3 that is long in the X direction, and a driver's cab 4. The loading platform 3 is configured to be able to support cargo K (see FIG. 5) or a pallet P (see FIG. 5) that supports the cargo K from below. The driver's cab 4 is provided at one end of the vehicle body 2 in the X direction. Operating units (such as a steering wheel and accelerator: not shown) that an operator uses to drive the transporter 1 are provided within the driver's cab 4.

[0020] 1, the running unit 6 has a running frame 6a, four wheels 6b, and a lifting unit 6c. The running unit 6 may have any configuration as long as it can run the vehicle body 2. The running unit 6 is also provided with a shock absorber (not shown) for absorbing shocks caused by unevenness in the ground.

[0021] The four wheels 6b have rubber tires and are arranged two by two apart in the X direction, forming two pairs of wheels 6b. The two wheels 6b of each pair are arranged along the Y direction, sandwiching the traveling frame 6a. The four wheels 6b are each arranged so that their orientation relative to the traveling frame 6a can change, thereby changing the traveling direction of the vehicle body 2 together with the traveling unit 6. The traveling frame 6a is provided with a transmission mechanism (not shown) that transmits driving force from the engine to at least one pair of wheels 6b.

[0022] As shown in Fig. 3, the traveling unit 6 is provided with a drive adjustment device 81 and a steering device 82. The drive adjustment device 81 is controlled by the control unit 7 and adjusts the drive force transmitted from the engine to the transmission mechanism. The steering device 82 is controlled by the control unit 7 and changes the direction of at least one pair of wheels 6b out of the two pairs of wheels 6b. The transporter 1 of this embodiment is a vehicle that normally travels and steers automatically under the control of the control unit 7 without being operated by an operator.

[0023] The lifting unit 6c is a known lifting device capable of raising and lowering the car body 2 together with the loading platform 3 in the Z direction. The lifting unit 6c is configured to be able to raise and lower the car body 2 between an upper limit height and a lower limit height. In this embodiment, the lower limit height of the car body 2 arranged by the lifting unit 6c is the height shown in FIG. 1. Note that the height of the car body 2 in this embodiment refers to the height of the top surface of the loading platform 3 from the ground. The upper limit height of the car body 2 arranged by the lifting unit 6c is approximately the same height level in the Z direction as the top plate 4a of the cab 4 when the car body 2 is at the lower limit height, as shown in FIG. 1. Note that the lower limit height and upper limit height of the car body 2 may be set as appropriate.

[0024] 1 and 2, the transporter 1 also has a known linear actuator 20 and a distance meter 30. The linear actuator (support mechanism) 20 is fixed to an end surface 2a of the car body 2 on the driver's cab 4 side in the X direction. More specifically, the linear actuator 20 is fixed to the center position of the end surface 2a in the Y direction. Note that the linear actuator 20 may be fixed to a position other than the center position of the end surface 2a in the Y direction.

[0025] As shown in Fig. 2, the linear actuator 20 has a guide 21 and a slider 22. The guide 21 has a plate shape extending in the Y direction and the Z direction. The guide 21 is formed to extend elongated along the Z direction. The slider 22 also has a plate shape extending in the Y direction and the Z direction. The slider 22 is also formed to extend elongated along the Y direction.

[0026] 2, the slider 22 is longer in the Y direction than the guide 21 and is supported by the guide 21 so as to be slidable along the Z direction. The slider 22 also has a base 23 formed at the lower end of an outer surface 22a on the outer side in the X direction. The base 23 protrudes in the X direction from the slider 22. The base 23 has a plate shape extending in the X and Y directions.

[0027] The rangefinder 30 is fixed to the upper surface of the base 23. A known 2D Lidar (Light Detection and Ranging or Laser Imaging Detection and Ranging) sensor is used as the rangefinder 30 in this embodiment. However, if a 3D Lidar sensor is used, the sensor itself is very expensive and the amount of data that can be acquired increases, resulting in higher costs and more complex control. For this reason, the present invention does not use a 3D Lidar sensor or an equivalent sensor. However, if used to acquire only horizontal distance data to an object, a 3D Lidar sensor or an equivalent sensor may be used.

[0028] The rangefinder 30 has an emitting unit that emits a laser beam to the area in front of the transport vehicle 1 and a receiving unit that receives the reflected light. The horizontal distance from the rangefinder 30 to a surrounding object is detected by measuring the time from laser emission to reception. The laser beam is scanned over a range of, for example, 90 degrees to the right and 90 degrees to the left, totaling 180 degrees, based on the direction of travel of the transport vehicle 1, and the distance to the object is measured in accordance with the angle. More specifically, the rangefinder 30 measures the horizontal distance to the object so that the outline of the object can be detected at the same height as the rangefinder 30. The laser irradiation range of the rangefinder 30 may be greater than or less than 90 degrees to the right. The laser irradiation range of the rangefinder 30 may be greater than or less than 90 degrees to the left. In this way, the laser irradiation range of the rangefinder 30 may be set appropriately.

[0029] Here, measurement of the distance to an object using the rangefinder 30 will be described. As shown in FIG. 4, a laser is emitted from the rangefinder 30 of the transporter 1 to scan a range of 180 degrees in the travel area. This allows the rangefinder 30 to detect the horizontal distance to, for example, multiple points G1 to G15 on the object. The number of points increases or decreases depending on the laser irradiation interval, which is set appropriately. Position data of the multiple points G1 to G15 on the object is obtained from distance data related to the horizontal distances to these multiple points G1 to G15. Then, the outer shape of the object can be recognized based on the position data of these multiple points G1 to G15. By repeatedly performing such scanning using the rangefinder 30 while the transporter 1 is traveling, position data corresponding to the outer shape of the object in the travel area can be obtained at any time.

[0030] In this embodiment, a 2D Lidar sensor is used, but any rangefinder may be used as long as it is capable of measuring the horizontal distance to an object as described above. The rangefinder 30 may also be fixed to the base 23 via a leveling device. The leveling device may be configured to operate so as to keep the rangefinder 30 horizontal. More specifically, it may be configured so that the irradiation axis from the rangefinder 30 can be kept horizontal. For example, a gimbal device may be used as the leveling device.

[0031] The linear actuator 20 supports the rangefinder 30 so that it can move between a first position shown in Fig. 2 and a second position shown in Fig. 1, which is higher than the first position. The first position is the height position of the rangefinder 30 when the lower end of the slider 22 and the lower end of the guide 21 are at the same height level, as shown in Fig. 2. The second position is the position shown in Fig. 1, which is the height position of the rangefinder 30 when the upper end of the slider 22 and the upper end of the guide 21 are at the same height level. Thus, the second position is vertically above the first position.

[0032] As shown in FIG. 3 , the control unit 7 includes a vehicle position estimation unit 71, a memory unit 72, an elevation difference calculation unit 73, a vehicle body lift control unit 74, and a travel control unit 75. The memory unit 72 stores various programs for controlling the transporter 1. The control unit 7 may include dedicated hardware, such as an application-specific integrated circuit (ASIC), that performs at least some of the various processes. The control unit 7 may be configured as a circuit including one or more processors operating according to a computer program, one or more dedicated hardware circuits such as ASICs, or a combination thereof. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. The memory, i.e., computer-readable medium, includes anything accessible by a general-purpose or special-purpose computer.

[0033] The memory unit 72 stores map data in which the position coordinates and posture of the vehicle body 2 are associated. The map data includes surrounding environment data for the travel area of ​​the transporter 1. The surrounding environment data is created in association with geographical position information. The position data of objects (such as obstacles and buildings in the travel area) in the surrounding environment data corresponds to the position data of the objects measured by the rangefinder 30 when the vehicle body 2 is at the first reference height and the rangefinder 30 is at a predetermined height. In other words, the position data of the objects in the surrounding environment data is position data indicating the outer position of the object at the same height level as the height of the rangefinder 30. More specifically, it is position data of the height of point A of the object shown in FIG. 5. The predetermined height here refers to the height of the rangefinder 30 from the ground, and is the height at which the rangefinder 30 is located exactly midway between the first position and the second position when the vehicle body 2 is at the first reference height. The predetermined height may be set as appropriate and is not particularly limited.

[0034] The first reference height of the vehicle body 2 is the height at which the vehicle body 2 is positioned between the lower limit height and the upper limit height, as shown in FIG. 5. When the transport vehicle 1 transports cargo K placed on a predetermined pallet P, the vehicle body 2 is raised by a first predetermined amount from the lower limit height. The height at which the vehicle body 2 is raised by the first predetermined amount from the lower limit height is the first reference height. Note that when cargo is loaded onto the vehicle body 2, the vehicle body 2 may become lower than the first reference height due to the load.

[0035] The vehicle position estimation unit 71 controls the rangefinder 30 to measure the horizontal distance to surrounding objects while the transporter 1 is traveling. The vehicle position estimation unit 71 also derives detected position data of objects at multiple points around the transporter 1 based on horizontal distance data to the objects measured by the rangefinder 30, and compares the detected position data at the multiple points with position data of the objects at the multiple points extracted from the map data in the memory unit 72, thereby estimating the vehicle position of the transporter 1.

[0036] The vehicle position is the position coordinates and attitude (inclination angle of the center line of the vehicle body 2 along the X direction with respect to an object on the XY plane) of the vehicle body 2. The position coordinates of the vehicle body 2 are coordinates indicating a point on the vehicle body 2, for example, coordinates at the installation position of the rangefinder 30 in the horizontal direction of the vehicle body 2.

[0037] When map data is stored in advance in the storage unit 72 of the transporter 1 when no cargo is loaded, as shown in FIG. 5, the vehicle body 2 is positioned at a first reference height, and the rangefinder 30 is positioned exactly in the center between the first position and the second position. In other words, the rangefinder 30 is positioned at a predetermined height. Then, while the transporter 1 is traveling in the traveling area, the rangefinder 30 detects the horizontal distances to multiple points on the object. From the distance data relating to the horizontal distances to these multiple points, position data of the multiple points on the object is obtained. Then, from the position data of these multiple points, the position data is stored as surrounding environment data of the map data. Note that data generated based on position data obtained by a device other than the rangefinder 30 may also be stored as map data.

[0038] The elevation difference deriving unit 73 derives the elevation difference of the vehicle body 2 based on the load detected by the load sensor 83. The load sensor (load detection unit) 83 is provided on the traveling unit 6 and detects the load applied to the vehicle body 2 when cargo is loaded on the loading platform 3. The elevation difference deriving unit 73 derives the degree to which the vehicle body 2 will sink from before the cargo is loaded, based on the load detected by the load sensor 83. More specifically, the elevation difference deriving unit 73 derives the elevation difference by substituting the load from the load sensor 83 into a calculation formula for deriving the degree to which the vehicle body 2 will sink depending on the load. The elevation difference deriving means in the present invention is composed of the elevation difference deriving unit 73 and the load sensor 83. Note that the elevation difference deriving means may be composed of a stroke sensor. In this case, the stroke sensor may directly detect the degree to which the vehicle body 2 will sink from before the cargo is loaded to after the cargo is loaded, and derive the elevation difference.

[0039] The vehicle body lifting control unit 74 controls the lifting unit 6c so that the vehicle body 2 is at a height equal to or higher than the lower limit height and equal to or lower than the upper limit height when cargo is loaded onto the loading platform 3. The vehicle body lifting control unit 74 also controls the lifting unit 6c so that the vehicle body 2 is at the lower limit height when cargo is unloaded from the loading platform 3. The vehicle body lifting control unit 74 also controls the lifting unit 6c so that the vehicle body 2 is at the lower limit height when the transporter 1 is traveling without any cargo or the like loaded.

[0040] The travel control unit 75 controls the drive adjustment device 81 and the steering device 82 in accordance with the program stored in the storage unit 72, thereby causing the transporter 1 to travel.

[0041] Furthermore, the vehicle position estimation unit 71 drives the linear actuator 20 based on the elevation difference derived by the elevation difference derivation unit 73 so that the rangefinder 30 is positioned at a predetermined height. When the transporter 1 is traveling without loading cargo or the like, the vehicle position estimation unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned at a second position. At this time, the vehicle body 2 is at a first reference height, as shown in FIG. 5, and the rangefinder 30 is at the same height level as the rangefinder 30 at the predetermined height. Furthermore, when the transporter 1 is loading cargo, the vehicle position estimation unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned at a center position between the first position and the second position.

[0042] Such a control unit 7 can move the transporter 1 to a desired position by controlling the drive adjustment device 81 and the steering device 82 while performing vehicle position estimation to estimate the position of the transporter 1 on a map.

[0043] Next, the operation of the transporter 1 when it travels with cargo K loaded will be described below. When no cargo K is loaded on the transporter 1, the vehicle body 2 is positioned at the lowest height, as shown in FIG. 5. At this time, the distance meter 30 is positioned at the second position. In this embodiment, cargo K, which has been placed in advance on a predetermined pallet P, is loaded onto the loading platform 3 together with the pallet P. The predetermined pallet P has an inverted U-shaped frame when viewed from the X direction, and is configured so that the loading platform 3 can be inserted into the lower part of the top plate P1 of the pallet P that supports the cargo K. In addition, the pallet P is formed long in the X direction.

[0044] The control unit 7 guides the transporter 1 so that the loading platform 3 of the transporter 1 is positioned below the top plate P1 of the pallet P. As shown in FIG. 5, when the loading platform 3 is positioned below the top plate P1 of the pallet P, the vehicle body lifting control unit 74 raises the vehicle body 2 by a first predetermined amount from the lowest height. As a result, the loading platform 3 lifts the top plate P1 of the pallet P, and the cargo K is loaded onto the transporter 1. At this time, the vehicle position estimation unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned in the middle between the first position and the second position.

[0045] Next, the elevation difference deriving unit 73 derives the degree to which the vehicle body 2 will sink before the cargo K is loaded, based on the load of the cargo K and pallet P detected by the load sensor 83. That is, as shown in FIG. 6(a), even if the lifting unit 6c raises the vehicle body 2 by a first predetermined amount from the lowest height, the vehicle body 2 may sink by a distance T1 due to the load of the cargo K, etc. In other words, the distance meter 30 is positioned at a position that is the distance T1 below the predetermined height. The elevation difference deriving unit 73 derives the distance T1 that corresponds to the elevation difference from the load.

[0046] Next, as shown in Fig. 6(b), the vehicle position estimation unit 71 drives the linear actuator 20 so that the slider 22 rises by the distance T1, which is the difference in elevation derived by the elevation difference derivation unit 73. As a result, the rangefinder 30 is positioned at a predetermined height.

[0047] Thereafter, the control unit 7 guides the vehicle 1 to the destination position. At this time, while the vehicle 1 is traveling, the control unit 7 measures the horizontal distance to an object around the vehicle 1 using the rangefinder 30. Then, the vehicle position estimation unit 71 acquires detected position data of the object at multiple points around the vehicle 1 based on the horizontal distance data to the object measured by the rangefinder 30, and estimates the vehicle position of the vehicle 1 by comparing the detected position data with position data of the object at multiple points extracted from the map data in the memory unit 72. Even when the vehicle 1 is loaded with cargo K, the rangefinder 30 is positioned at a predetermined height, so the accuracy of the acquired detected position data of the object at multiple points is improved. Therefore, the estimation accuracy of the vehicle position is maintained.

[0048] If the transporter 1 is driven with the rangefinder 30 positioned a distance T1 below the predetermined height, the detected position data obtained based on the rangefinder 30 will be position data for the height of the object at point B (below point A) shown in FIG. 5. In this case, the estimated vehicle position will be closer to the object than when the rangefinder 30 is positioned at the predetermined height. As a result, the estimation accuracy of the vehicle position will decrease. However, in this embodiment, the rangefinder 30 is positioned at the predetermined height, so the estimation accuracy of the vehicle position is maintained.

[0049] The control unit 7 then controls the drive adjustment device 81 and the steering device 82 while estimating the position of the transporter 1 on the map, thereby guiding the transporter 1 to the destination position.

[0050] When the transport vehicle 1 reaches the destination position, the vehicle body lifting control unit 74 controls the lifting unit 6c so that the vehicle body 2 reaches the lower limit height. As a result, the pallet P on which the cargo K is placed is lowered. At this time, the vehicle position estimation unit 71 drives the linear actuator 20 to raise the slider 22 so that the range finder 30 is positioned at the second position, as shown in FIG. 5. Then, the control unit 7 guides the transport vehicle 1 away from the pallet P. In this way, even when the cargo K and pallet P are not loaded, the range finder 30 is positioned at a predetermined height. Therefore, the estimation accuracy of the vehicle position is maintained, as described above.

[0051] As described above, according to the transporter 1 of this embodiment, the linear actuator 20 can move the rangefinder 30 between the first position and the second position. Therefore, even if the vehicle body 2 is displaced relative to the first reference height when cargo K is loaded, the height of the rangefinder 30 can be adjusted to a predetermined height, and the height of the rangefinder 30 from the ground can be kept constant. Therefore, it is possible to suppress a decrease in the estimation accuracy of the vehicle's position caused by the height of the vehicle body 2. As a result, it is possible to maintain the guidance accuracy of the transporter 1.

[0052] The vehicle position estimation unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned at a predetermined height based on the elevation difference derived by the elevation difference derivation unit 73. This makes it possible to position the rangefinder 30 at a predetermined height even if the height of the vehicle body 2 when loaded with cargo K differs from the first reference height of the vehicle body 2. This makes it possible to further suppress a decrease in the estimation accuracy of the vehicle position caused by the height of the vehicle body 2.

[0053] The elevation difference deriving unit 73 derives the elevation difference based on the load detected by the load sensor 83 (in this embodiment, the load applied to the vehicle body 2 when cargo K placed on the pallet P is loaded). This makes it possible to move the distance meter 30 based on the elevation difference derived based on the load.

[0054] The transporter 1 is provided with a running section 6 having a lifting section 6c. As a result, even when the vehicle body 2 is raised by the lifting section 6c to load cargo K and the cargo K is transported by the transporter 1, it is possible to suppress a decrease in the estimation accuracy of the vehicle position due to the height of the vehicle body 2.

[0055] The linear actuator 20 moves the rangefinder 30 along the Z direction (up-down direction). This allows the rangefinder 30 to be moved along the Z direction, minimizing the distance traveled by the rangefinder 30 when positioning the rangefinder 30 at a predetermined height. Furthermore, the rangefinder 30 does not shift horizontally when moved between the first position and the second position. This facilitates deriving detected position data of an object based on horizontal distance data measured by the rangefinder 30. If the rangefinder 30 is moved along a direction intersecting the up-down direction, the horizontal position of the rangefinder 30 changes accordingly. Therefore, the detected position data must be derived taking into account the horizontal movement amount. However, in this embodiment, the linear actuator 20 moves the rangefinder 30 along the up-down direction, eliminating the need to consider the horizontal movement amount of the rangefinder 30, making it easier to derive detected position data.

[0056] As a modified example, when the transporter 1 transports cargo K placed on a specific pallet P, the vehicle body 2 may be raised from the lower limit height by a second predetermined amount greater than the first predetermined amount. That is, as shown in FIG. 7(a), when the loading platform 3 is positioned below the top plate P1 of the pallet P, the vehicle body lifting control unit 74 raises the vehicle body 2 from the lower limit height by the second predetermined amount. The second predetermined amount is greater than the first predetermined amount by an amount R equivalent to the maximum range over which the rangefinder 30 can be moved by the linear actuator 20 (the difference in height between the first position and the second position). As a result, the loading platform 3 lifts the top plate P1 of the pallet P, and the cargo K is loaded onto the transporter 1. At this time, the vehicle position estimation unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned at a center position between the first position and the second position. The X, Y, and Z directions described above are also shown in FIG. 7 .

[0057] Next, the elevation difference deriving unit 73 derives the degree to which the vehicle body 2 sinks before the cargo K is loaded, based on the load of the cargo K and the pallet P detected by the load sensor 83. That is, as shown in FIG. 7(a), even though the lifting unit 6c raises the vehicle body 2 by the second predetermined amount from the lower limit height, the vehicle body 2 sinks by the distance T1 due to the load of the cargo K and the pallet P, as described above. As a result, the distance T2 obtained by subtracting the distance T1 from the amount (distance) obtained by subtracting the first predetermined amount from the second predetermined amount is the deviation amount from the predetermined height of the distance meter 30. Therefore, the elevation difference deriving unit 73 in this modification derives the distance T2 corresponding to the elevation difference. Note that if the weight of the cargo K and the pallet P changes from that in the above embodiment, the derived distance T1 changes accordingly.

[0058] Next, as shown in FIG. 7(b), if the distance T2 as the difference in elevation derived by the elevation difference derivation unit 73 is positive, the vehicle position estimation unit 71 drives the linear actuator 20 to lower the slider 22 by the distance T2. As a result, the rangefinder 30 is positioned at a predetermined height. On the other hand, if the distance T2 derived by the elevation difference derivation unit 73 is negative, the vehicle position estimation unit 71 drives the linear actuator 20 to raise the slider 22 by the distance T2. As a result, the rangefinder 30 is positioned at a predetermined height.

[0059] The control unit 7 then controls the drive adjustment device 81 and the steering device 82 while estimating the position of the transporter 1 on the map, thereby guiding the transporter 1 to the destination position.

[0060] In the transporter 1 of this modified example, even if the vehicle body 2 is displaced relative to the first reference height when cargo K is loaded, it is possible to adjust the height of the rangefinder 30 to a predetermined height. Therefore, it is possible to suppress a decrease in the estimation accuracy of the vehicle position caused by the height of the vehicle body 2. As a result, it is possible to maintain the guidance accuracy of the transporter 1.

[0061] As another modification, when transporting cargo K placed on a specific pallet P, the vehicle body 2 may be raised from the lower limit height by a third predetermined amount greater than the second predetermined amount. The third predetermined amount is greater than the first predetermined amount by an amount R corresponding to the maximum range over which the rangefinder 30 can be moved by the linear actuator 20 (the difference in elevation between the first position and the second position). In this case, it is desirable that the memory unit 72 store map data other than the above-mentioned map data. The other map data is position data at a height different from that of the above-mentioned map data, and includes position data of an object corresponding to when the vehicle body 2 is at the second reference height and the rangefinder 30 is at the other predetermined height. The other map data is the same as the above-mentioned map data except for the position data at a different height. The second reference height is a height above the first reference height by the difference in elevation between the first position and the second position and lower than the above-mentioned upper limit height. The other predetermined height is the height of the rangefinder 30 from the ground, i.e., the height at which the rangefinder 30 is located exactly midway between the first position and the second position when the vehicle body 2 is at the second reference height. The other predetermined height may be set as appropriate and is not particularly limited.

[0062] When storing other map data in advance in the storage unit 72 of the transporter 1 when no cargo is loaded, the vehicle body 2 is positioned at the second reference height, and the rangefinder 30 is positioned exactly midway between the first and second positions. In other words, the rangefinder 30 is positioned at another predetermined height. Then, while the transporter 1 is traveling in the traveling area, the rangefinder 30 detects the horizontal distances to multiple points on the object. Based on the distance data relating to the horizontal distances to these multiple points, position data of the multiple points on the object is obtained. Based on the position data of these multiple points, the position data is then stored as surrounding environment data of the other map data. Note that data generated based on position data obtained by a device other than the rangefinder 30 may also be stored as the other map data.

[0063] As shown in Figure 8(a), when the loading platform 3 is positioned below the top plate P1 of the pallet P, the vehicle body lifting control unit 74 raises the vehicle body 2 by a third predetermined amount from the lowest height. As a result, the loading platform 3 lifts the top plate P1 of the pallet P, and the cargo K is loaded onto the transporter 1. At this time, the vehicle position estimating unit 71 drives the linear actuator 20 so that the rangefinder 30 is positioned at a center position between the first position and the second position. Note that the above-mentioned X direction, Y direction, and Z direction are also shown in Figure 8.

[0064] Next, the elevation difference deriving unit 73 derives the degree to which the vehicle body 2 sinks from before the cargo K is loaded, based on the load of the cargo K and the pallet P detected by the load sensor 83. That is, as shown in FIG. 8(a), even though the lifting unit 6c raises the vehicle body 2 by a third predetermined amount from the lower limit height, the vehicle body 2 sinks by a distance T1 as described above due to the load of the cargo K and the pallet P. As a result, a distance (distance) is derived by subtracting the sum (second reference height) of the first predetermined amount and the amount R corresponding to the maximum range over which the rangefinder 30 can move from the third predetermined amount, and the distance T3 obtained by subtracting the distance T1 from the third predetermined amount is the deviation of the rangefinder 30 from another predetermined height. Therefore, the elevation difference deriving unit 73 in this modification derives the distance T3 corresponding to the elevation difference.

[0065] Next, as shown in FIG. 8(b), if the distance T3 as the difference in elevation derived by the elevation difference derivation unit 73 is positive, the vehicle position estimation unit 71 drives the linear actuator 20 to lower the slider 22 by the distance T3. As a result, the rangefinder 30 is positioned at another predetermined height. On the other hand, if the distance T3 derived by the elevation difference derivation unit 73 is negative, the vehicle position estimation unit 71 drives the linear actuator 20 to raise the slider 22 by the distance T3. As a result, the rangefinder 30 is positioned at another predetermined height.

[0066] Next, when the first position when the cargo K is loaded is equal to or lower than the second position when the vehicle body 2 is at the first reference height, the vehicle position estimation unit 71 estimates the vehicle position based on the detected position data of the object and the position data of the object included in the map data. Whether the first position at this time is equal to or lower than the second position when the vehicle body 2 is at the first reference height can be determined by checking whether the sum of the distance T1 and the amount R corresponding to the maximum range of movement of the rangefinder 30 is equal to or greater than the amount obtained by subtracting the first predetermined amount from the third predetermined amount. In other words, when the sum of the distance T1 and the amount R corresponding to the maximum range of movement of the rangefinder 30 is less than the amount obtained by subtracting the first predetermined amount from the third predetermined amount, the first position is higher than the second position when the vehicle body 2 is at the first reference height.

[0067] On the other hand, the vehicle position estimation unit 71 estimates the vehicle position based on the detected position data of the object and the position data of the object contained in another map data when the first position when cargo K is loaded is higher than the second position when the vehicle body 2 is at the first reference height.

[0068] The control unit 7 then controls the drive adjustment device 81 and the steering device 82 while estimating the position of the transporter 1 on the map, thereby guiding the transporter 1 to the destination position.

[0069] In the transporter 1 of this modified example, even if the vehicle body 2 is displaced relative to the second reference height when cargo K is loaded, the height of the rangefinder 30 can be adjusted to another predetermined height. Therefore, it is possible to suppress a decrease in the estimation accuracy of the vehicle's position caused by the height of the vehicle body 2. As a result, it is possible to maintain the guidance accuracy of the transporter 1. Furthermore, even when the vehicle body 2 is above the first reference height by more than the difference in elevation between the first position and the second position, the estimation accuracy of the vehicle's position in the travel area is improved.

[0070] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible within the scope of the claims. For example, the transporter 1 may have cargo K placed directly on the loading platform 3. In other words, a pallet P may not be used. In this case, when loading cargo K onto the transporter 1, the vehicle body 2 does not need to be raised, but it is preferable to position the vehicle body 2 at the first reference height in advance. At this time, the distance meter 30 is also positioned at a position midway between the first position and the second position.

[0071] The transporter 1 may not have the lifting unit 6c. In other words, the transporter 1 may be configured such that the vehicle body 2 cannot be selectively raised or lowered when loading cargo. In this case, the height of the vehicle body 2 when no cargo is loaded is the reference height. When the vehicle body 2 is at the reference height, the rangefinder 30 is placed at the first position. The rangefinder 30 at the first position corresponds to the above-mentioned predetermined height. This allows the rangefinder 30 to be moved over a larger area based on the elevation difference derived by the elevation difference derivation unit 73. In this case, it is desirable that the map data include object position data corresponding to when the vehicle body 2 is at the reference height and the rangefinder 30 is at the first position. This, as described above, makes it possible to suppress a decrease in the estimation accuracy of the vehicle's position due to the height of the vehicle body 2. As a result, it is possible to maintain the guidance accuracy of the transporter 1. When the vehicle body 2 is at the reference height, the rangefinder 30 may be placed higher than the first position to appropriately set the predetermined height.

[0072] The transporter 1 in the above-described embodiment and each modified example may have a movement amount detection unit (e.g., a stroke sensor) that detects the amount of movement of the vehicle body 2 in the Z direction by the lifting unit 6c. In this case, the movement amount detected by the movement amount detection unit may be the above-described predetermined amount (first to third predetermined amount). In the transporter 1 in the above-described embodiment and each modified example, the predetermined amount (first to third predetermined amount) by which the vehicle body 2 is raised from the lower limit height when loading cargo K is determined in advance by a program, but the predetermined amount may also be adjusted arbitrarily. Even if the predetermined amount is adjusted arbitrarily, the movement amount detection unit detects the movement amount, so it is possible to position the distance meter 30 at the predetermined height (or another predetermined height) in the same manner as described above, and the same effect can be obtained.

[0073] In the transporter 1 in the above-described embodiment and each modified example, the control unit 7 controls the linear actuator 20 to move the rangefinder 30 in the Z direction. However, instead of the linear actuator 20, a support mechanism may be provided that allows an operator to manually change the height position of the rangefinder 30. In this case, the support mechanism may be operated so that the height of the rangefinder 30 changes by the amount of change in the vehicle body height before and after loading cargo onto the transporter. This achieves the same effect as described above. Furthermore, the support mechanism may have any configuration as long as it is capable of moving the rangefinder 30 in a direction intersecting the horizontal direction.

[0074] Furthermore, in the transport vehicle 1 in the above-described embodiment and each modified example, the linear actuator 20 and the rangefinder 30 as a support mechanism are provided only at one end of the vehicle body 2 in the X direction, but these support mechanisms and rangefinders 30 may also be provided at the other end of the vehicle body 2 in the X direction and / or at least one of both ends in the Y direction.

[0075] In the above-described embodiment and each modified example, the rangefinder 30 arranged at the first position and the rangefinder 30 arranged at the second position are not arranged with a horizontal offset, but they may be slightly offset in the horizontal direction. In other words, the first position and the second position may be offset in the horizontal direction. [Explanation of symbols]

[0076] 1 Transport vehicle 2. Body 3 Cargo bed 6 Running part 6c Lifting section 20 Linear actuator (support mechanism) 30 Rangefinder 71 Vehicle position estimation unit 72 Memory section 73 Elevation difference derivation unit (part of elevation difference derivation means) 83 Load sensor (load detection part) K cargo P Pallet (part of cargo)

Claims

1. A transport vehicle having a body including a loading platform, a rangefinder for measuring the horizontal distance to an object; a support mechanism attached to the vehicle body and configured to movably support the rangefinder between a first position and a second position higher than the first position; a storage unit that stores map data including position data of the object corresponding to when the vehicle body is at a reference height and the range finder is at a predetermined height in a travel area of ​​the transporter; a vehicle position estimation unit that estimates the vehicle position based on detected position data of the object based on distance data to the object measured by the rangefinder and position data of the object included in the map data.

2. The vehicle further includes an elevation difference deriving means for deriving an elevation difference between the vehicle body when loaded with cargo and the vehicle body when not loaded with cargo and at the reference height, the support mechanism has an actuator that moves the rangefinder, The transporter according to claim 1, characterized in that the vehicle position estimation unit drives the actuator so that the rangefinder is positioned at the predetermined height based on the elevation difference derived by the elevation difference derivation means when cargo is loaded.

3. The transporter according to claim 2, characterized in that the elevation difference deriving means has a load detection unit that detects the load applied to the vehicle body when cargo is loaded, and derives the elevation difference based on the load detected by the load detection unit.

4. The vehicle further includes a running unit that can run while supporting the vehicle body, 2. The transporter according to claim 1, wherein the traveling unit has a lifting unit that can raise and lower the vehicle body to a height equal to or higher than the reference height.

5. the second position is vertically above the first position, 5. The transporter according to claim 1, wherein the support mechanism moves the range finder in an up-down direction.

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