Cargo support device and unmanned cargo handler
By designing multiple legs and drive units in coordination, the unmanned cargo handling machine can support cargo of different sizes and shapes, solving the problem of fixed size and shape in existing technologies and enhancing adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-03-24
- Publication Date
- 2026-05-15
AI Technical Summary
In existing technologies, the size and shape of goods such as containers are fixed and difficult to change when supporting small drones.
A cargo support device was designed, which enables the movement and rotation of the legs through the cooperation of multiple legs and a drive unit, and can adapt to cargo of different sizes and shapes.
It enables effective support for goods of different sizes and shapes, enhancing the adaptability of the unmanned cargo handling machine.
Smart Images
Figure CN117087859B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to cargo support devices and unmanned cargo handling machines. Background Technology
[0002] International Publication No. 2020 / 194533 discloses a handling device for moving containers or the like by supporting them on the underside of a small drone.
[0003] However, in the handling device described in International Publication No. 2020 / 194533, the size and shape of the container or the like that which can support the lower part of a small drone are fixed, and it is difficult to change the size and shape of the container or the like. Summary of the Invention
[0004] In view of the above facts, the present invention aims to provide a cargo support device and an unmanned cargo handling machine capable of supporting goods of different sizes and shapes.
[0005] The first type of cargo support device includes: a base on which a small drone is mounted; multiple legs disposed on the lower side of the base, each having two abutment portions, the two abutment portions respectively abutting against two adjacent sides of the cargo viewed from above, the multiple legs supporting corner portions of the cargo when the two abutment portions are respectively abutting against two adjacent sides of the cargo; a first support portion fixed to the lower side of the base, supporting each leg so that it can move towards the cargo side and the opposite side of the cargo; a drive portion that, through operation, moves each leg towards the cargo side or the opposite side of the cargo; and a second support portion disposed between the base and each leg, supporting each leg so that it can rotate axially in the vertical direction.
[0006] According to the first embodiment of the cargo support device, each leg is supported by a first support fixed to a base. Therefore, by operating the drive unit, each leg can be moved towards the cargo side. When each leg moves towards the cargo side, each leg supports the corner portion of the cargo with its two abutting parts abutting against the two adjacent sides of the cargo viewed from above. Here, the first embodiment of the cargo support device includes a second support that supports each leg so that it can rotate axially in the vertical direction. Therefore, even if the size and shape of the cargo viewed from above are different, by rotating each leg axially in the vertical direction, the two abutting parts of each leg can abut against the two adjacent sides of the cargo. Thus, according to the first embodiment of the cargo support device, cargoes of different sizes and shapes can be supported.
[0007] The second type of cargo support device is based on the first type of cargo support device. The cargo support device further includes a rotation limiting part, which limits the rotation of each leg in the up-down direction as an axial direction. The rotation limiting part also limits the rotation of each leg in the up-down direction as an axial direction when the leg is not supporting the cargo.
[0008] According to the second embodiment of the cargo support device, when each leg is not supporting cargo, the rotation of each leg along the vertical axis is limited by the rotation limiting part. This suppresses unnecessary rotation of each leg along the vertical axis.
[0009] The third type of cargo support device is based on the second type of cargo support device, wherein the rotation limiting part is formed as a rotation limiting spring, a portion of which is locked to the leg, and the leg is allowed to rotate axially in the up-down direction by the deformation of the rotation limiting spring.
[0010] According to the third embodiment of the cargo support device, the legs are allowed to rotate axially in the vertical direction by means of the deformation of the rotation-limiting spring. In this structure, the restoring force of the deformation-limiting spring allows the legs to return to their original position.
[0011] The fourth type of unmanned cargo handling machine includes: a small drone; a base on which the small drone is mounted; multiple legs disposed on the lower side of the base, each having two abutment portions, the two abutment portions respectively abutting against two adjacent sides of the cargo viewed from above, the multiple legs supporting the corner portions of the cargo when the two abutment portions are respectively abutting against the two adjacent sides of the cargo; a first support portion fixed to the lower side of the base, supporting each leg so that it can move towards the cargo side and the opposite side of the cargo; a drive unit that, through operation, moves each leg towards the cargo side or the opposite side of the cargo; and a second support portion disposed between the base and each leg, supporting each leg so that it can rotate axially in the vertical direction.
[0012] According to the fourth embodiment of the unmanned cargo handling machine, a small drone can transport supported goods. Furthermore, in this fourth embodiment, each leg is supported by a first support fixed to a base. Therefore, by operating a drive unit, each leg can move towards the cargo side. When each leg moves towards the cargo side, each leg supports the corner portion of the cargo with its two abutting parts abutting against the two adjacent sides of the cargo viewed from above. Here, the fourth embodiment of the unmanned cargo handling machine includes a second support that supports each leg so that it can rotate axially in the vertical direction. Therefore, even if the size and shape of the cargo viewed from above are different, by rotating each leg axially in the vertical direction, the two abutting parts of each leg can abut against the two adjacent sides of the cargo. Thus, the fourth embodiment of the unmanned cargo handling machine can support cargo of different sizes and shapes.
[0013] The cargo support device and unmanned cargo handling machine of the present invention have the excellent effect of being able to support cargoes of different sizes and shapes. Attached Figure Description
[0014] Exemplary embodiments of the present invention will be described in detail with reference to the following figures, wherein:
[0015] Figure 1 This is a 3D diagram representing an unmanned cargo handling machine;
[0016] Figure 2 This is a 3D diagram showing an unmanned cargo handling machine, illustrating the cargo support device supporting the cargo.
[0017] Figure 3 This is a three-dimensional diagram showing the cargo support device;
[0018] Figure 4 This is a top view of the cargo support device, omitting the illustration of the plate;
[0019] Figure 5 This is a perspective view of the cargo support device viewed from above, omitting the illustration of the plate.
[0020] Figure 6 It is an enlarged perspective view showing the area near the rotating support.
[0021] Figure 7 It is a three-dimensional view showing the cargo support device and the cargo, indicating the state before each leg supports the cargo;
[0022] Figure 8 This is a top view of the cargo support device and cargo, omitting the illustration of the plates, showing the state before each leg supports the cargo;
[0023] Figure 9 It is a three-dimensional view showing the cargo support device and the cargo, indicating the state of each leg supporting the cargo;
[0024] Figure 10 This is a top view of the cargo support device and cargo, omitting the illustration of the plates, showing the state of each leg supporting the cargo;
[0025] Figure 11 It is a bottom view of the cargo support device and the cargo as seen from below;
[0026] Figure 12 Is with Figure 11 The corresponding bottom view omits the illustration of the goods;
[0027] Figure 13 It is Figure 11 An enlarged perspective view of the area near the rotating support in the desired state;
[0028] Figure 14 It is a bottom view of the cargo support device and the cargo as seen from below;
[0029] Figure 15 Is with Figure 14 The corresponding bottom view omits the illustration of the goods; and
[0030] Figure 16 It is Figure 14 An enlarged perspective view of the area near the rotating support in the specified state. Detailed Implementation
[0031] use Figures 1-6 This describes an embodiment of the unmanned cargo handling machine 10 of the present invention.
[0032] like Figure 1 and Figure 2 As shown, the unmanned cargo handling machine 10 of this embodiment includes a small drone 12 and a cargo support device 14 installed below the small drone 12.
[0033] like Figure 1 , Figure 3 , Figure 4 and Figure 5 As shown, the cargo support device 14 includes an aircraft fixing part 16 for securing the small drones 12 and a pair of grounding parts 18 that are in contact with the ground in a landing state. It should be noted that in this embodiment, six small drones 12 are fixed to the aircraft fixing part 16. Furthermore, the pair of grounding parts 18 includes a grounding part body 18A extending horizontally and in contact with the ground, and a central leg 18B extending upward from the center of the grounding part body 18A along its length. The upper end of the central leg 18B is connected to the lower part of the aircraft fixing part 16.
[0034] In addition, the cargo support device 14 includes a base plate 20 disposed on the lower side of the aircraft fixing part 16 and connected to the aircraft fixing part 16. Furthermore, the cargo support device 14 includes four legs 22 serving as cargo support parts, four linear guides 24 serving as first support parts, a linkage mechanism 26, and an actuator 28.
[0035] like Figure 3 As shown, the plate 20 is formed as a plate with its thickness along the vertical direction, and is a roughly rectangular shape in which the sides of the rectangle curve inward when viewed from above. Legs 22 are installed at the four corners of the plate 20.
[0036] The leg portion 22 includes: two abutment portions 22A spaced apart along a horizontal direction orthogonal to the vertical direction; an upper connecting portion 22B connecting the upper ends of the two abutment portions 22A horizontally; and a lower connecting portion 22C connecting the lower ends of the two abutment portions 22A horizontally. The two abutment portions 22A are formed as cylindrical rods with the vertical direction as their axial direction. The upper connecting portion 22B is formed as a plate extending horizontally with the vertical direction as its thickness direction. The upper end of one abutment portion 22A is fixed to one end of the upper connecting portion 22B, and the upper end of the other abutment portion 22A is fixed to the other end of the upper connecting portion 22B. The lower connecting portion 22C is formed as a plate extending horizontally with the vertical direction as its thickness direction. The lower end of one abutment portion 22A is fixed to one end of the lower connecting portion 22C, and the lower end of the other abutment portion 22A is fixed to the other end of the lower connecting portion 22C. Here, as... Figure 2 As shown, the lower connecting portion 22C serves as the part that supports the cargo 30 from below. Furthermore, the two abutting portions 22A serve as the parts that support the cargo 30 from the side. It should be noted that the four legs 22 each have the same structure.
[0037] like Figure 3 and Figure 4 As shown, the linear guide 24 is formed as a plate extending horizontally in the thickness direction with the vertical direction as the direction. Viewed from above, the linear guide 24 has a rectangular shape. Furthermore, the four linear guides 24 are fixed to the plate 20 with their respective corners positioned below the plate 20. When viewed from above, one side of each linear guide 24 faces the center (center of view) of the plate 20 along its length. The four legs 22 are supported on the four linear guides 24 via the sliding portion 42 and the rotating support portion 44, which will be described later. Each leg 22 can move along its respective linear guide 24 from the corner of the plate 20 towards the center and from the center of the plate 20 towards the corner.
[0038] The linkage mechanism 26 includes a central link 32 located on the lower side of the center of the plate 20 when viewed from above, and four outer links 34 each connected to the central link 32. For example... Figure 4 and Figure 5 As shown, the central connecting rod 32 includes: a rotating portion 32A rotatably supported on the plate 20 with the vertical direction as the axial direction; and four protruding arms 32B extending outward from the rotating portion 32A in the rotational radial direction. The four protruding arms 32B are arranged with spacing along the rotational circumference of the rotating portion 32A. One end of each of the four outer connecting rods 34 is connected via ball joints to the end of each of the four protruding arms 32B on the opposite side of the rotating portion 32A. The other end of each of the four outer connecting rods 34 is connected via ball joints to four sliding brackets 46, which will be described later.
[0039] like Figure 5 As shown, actuator 28, as an example, is a motor actuator that rotates the output shaft 28A. This actuator 28 is configured on plate 20 (see reference 20). Figure 3 The actuator 28 is fixed to the plate 20 at its upper side. A first rod 36 is fixed to the output shaft 28A of the actuator 28. The first rod 36 is inserted into an opening formed in the plate 20. Thus, the end of the first rod 36 opposite to the output shaft 28A is located on the lower side relative to the plate 20. Moreover, one end of the second rod 38 is connected to the end of the first rod 36 opposite to the output shaft 28A via a ball joint. Furthermore, the other end of the second rod 38 is connected to the protruding arm 32B of the central connecting rod 32 via a ball joint. Thus, the output shaft 28A of the actuator 28 and the central connecting rod 32 are connected via the first rod 36 and the second rod 38. As a result, the central connecting rod 32 rotates in conjunction with the rotation of the output shaft 28A of the actuator 28. Here, the actuator 28, the first rod 36, the second rod 38, the central connecting rod 32, and the four outer connecting rods 34 constitute a drive unit 40 that moves each leg 22 toward the cargo 30 or the opposite side of the cargo 30.
[0040] As previously described, the leg 22 is supported on the linear guide 24 via the sliding portion 42 and the rotating support portion 44. More specifically, as... Figure 6 As shown, the leg 22 is supported on the linear guide 24 via a sliding part 42, a sliding bracket 46, and a swivel support part 44. The sliding part 42 engages with the linear guide 24. The sliding part 42 slides (moves) along the length of the linear guide 24. Furthermore, a sliding bracket 46 is fixed to the lower part of the sliding part 42. Figure 5As shown, the other end of the outer connecting rod 34 is connected via a ball joint to the end of the sliding bracket 46 opposite to the sliding portion 42. Furthermore, a swivel support 44, serving as a second support, protrudes downwards from the lower part of the sliding bracket 46. This swivel support 44 engages with the central portion of the upper connecting portion 22B of the leg 22 along its length, thereby supporting the leg 22 in a manner that allows it to rotate axially in the vertical direction.
[0041] A rotation limiting spring 48, serving as a rotation limiting component, is provided between the upper connecting portion 22B of the leg 22 and the sliding bracket 46. The rotation limiting spring 48 is, for example, a torsion spring. This rotation limiting spring 48 passes through the rotation support portion 44. Furthermore, one end 48A of the rotation limiting spring 48 is engaged with a hole formed in the upper connecting portion 22B. The other end 48B of the rotation limiting spring 48 is engaged with a hole formed in the sliding bracket 46. The deformation of the rotation limiting spring 48 allows the leg 22 to rotate axially in the vertical direction.
[0042] (The function and effects of this implementation method)
[0043] Next, the function and effects of this implementation method will be explained.
[0044] like Figure 1 and Figure 2 As shown, in the unmanned cargo handling machine 10 of this embodiment, when the grounding part 18 is in contact with the ground (unmanned cargo handling machine 10 is in the landing state), the cargo support device 14 can support the cargo 30.
[0045] In detail, Figure 7 and Figure 8 In the shown state, the rectangular cargo 30 is positioned below the plate 20, and each leg 22 is separated from the cargo 30. In this state, each leg 22 is restrained by a rotational limiting spring 48 (see reference). Figure 6 The legs 22 are kept in a fixed posture. This limits unnecessary rotation of each leg 22 along the vertical axis when it is not supporting the cargo 30. It should be noted that the posture of each leg 22 relative to each linear guide 24 when it is not supporting the cargo 30 is called "standard posture A1".
[0046] Here, the cargo 30 has a rectangular upper surface 30A and a lower surface 30B (see reference). Figure 11The four sides 30C connect the upper surface 30A and the lower surface 30B in the vertical direction. The two sides 30C with the smaller horizontal dimension are called the first sides 30C1, and the two sides 30C with a horizontal dimension larger than the first sides 30C1 are called the second sides 30C2. It should be noted that... Figures 7-11 The cargo 30 shown is a standard aspect ratio cargo 30 with the ratio of the horizontal dimension of the first side 30C1 to the horizontal dimension of the second side 30C2 (hereinafter referred to as "aspect ratio") set to a defined aspect ratio.
[0047] like Figure 5 As shown, when the output shaft 28A of the actuator 28 rotates to one side (the direction of arrow C1) and the central connecting rod 32 rotates to one side (the direction of arrow C2), the four outer connecting rods 34 pull the four sliding brackets 46. As a result, each leg 22 moves towards the cargo 30. It should be noted that the operating state of the drive unit 40 caused by rotating the output shaft 28A of the actuator 28 to one side (the direction of arrow C1) is referred to as the "operating state when supporting cargo," which is the first state.
[0048] like Figure 9 and Figure 10 As shown, when each leg 22 moves toward the cargo 30, the two abutting portions 22A of each leg 22 abut against the adjacent first side 30C1 and second side 30C2, respectively. Here, as... Figure 10 , Figure 11 , Figure 12 and Figure 13 As shown, in the case of a cargo 30 with a standard aspect ratio, each leg 22 hardly rotates from the standard posture A1. That is, in this embodiment, the standard posture A1 of each leg 22 is set corresponding to a cargo 30 with a standard aspect ratio. It should be noted that in Figure 12 and Figure 13 The illustration of cargo 30 is omitted in the text.
[0049] like Figure 9 , Figure 11 and Figure 12 As shown, when the two abutting portions 22A of each leg 22 abut against the adjacent first side 30C1 and second side 30C2 respectively, the lower connecting portion 22C of each leg 22 is arranged along the lower surface 30B of the cargo 30. Thus, the four corner portions 30D of the cargo 30 are supported by each leg 22.
[0050] In addition, such as Figure 2As shown, when each small drone 12 is in operation, each small drone 12 flies together with the cargo support device 14. Thus, the cargo 30 supported by the cargo support device 14 can be transported by air.
[0051] It should be noted that, in the landing state of the unmanned cargo handling vehicle 10, if... Figure 5 As shown, when the output shaft 28A of the actuator 28 rotates to the other side (opposite to the direction of arrow C1) and the central connecting rod 32 rotates to the other side (opposite to the direction of arrow C2), the four outer connecting rods 34 press down on the four sliding brackets 46. This causes each leg 22 to move to the opposite side of the cargo 30. As a result, the cargo 30 supported by each leg 22 can be unloaded from the cargo support device 14. It should be noted that the operating state of the drive unit 40 caused by rotating the output shaft 28A of the actuator 28 to the other side (opposite to the direction of arrow C1) is referred to as the second state, the "unloading operating state".
[0052] Figure 14 The cargo 30 shown is a flat cargo 30 with a first side 30C1 whose horizontal dimension is smaller than that of a standard cargo 30 in terms of length and width. The operation of each leg 22 when supporting the flat cargo 30 will be described below.
[0053] like Figure 14 , Figure 15 and Figure 16 As shown, when each leg 22 moves towards the cargo 30 side, firstly, the abutment portion 22A of one leg 22 abuts against the first side surface 30C1. With the abutment portion 22A of one leg 22 abutting against the first side surface 30C1, if each leg 22 moves further towards the cargo 30 side, each leg 22 rotates from the standard posture A1 to one side (the direction of arrow C3). It should be noted that when each leg 22 rotates from the standard posture A1 to one side, the rotation limiting spring 48 (see reference...) Figure 6 The legs 22 deform. When each leg 22 rotates from the standard position A1 to one side, the other abutting portion 22A of the leg 22 abuts against the second side surface 30C2. When the two abutting portions 22A of each leg 22 abut against the adjacent first side surface 30C1 and second side surface 30C2 respectively, the lower connecting portion 22C of each leg 22 is arranged along the lower surface 30B of the flat aspect ratio cargo 30. Thus, the four corner portions 30D of the flat aspect ratio cargo 30 are supported by each leg 22.
[0054] As described above, the cargo support device 14 of the unmanned cargo handling machine 10 in this embodiment can support cargo 30 of different sizes and shapes (length-to-width ratios).
[0055] Furthermore, starting from the state where the four corner portions 30D of the flat aspect ratio cargo 30 are supported by each leg 22, when each leg 22 moves to the opposite side of the flat aspect ratio cargo 30, the flat aspect ratio cargo 30 supported by each leg 22 is unloaded from the cargo support device 14. At this time, each leg 22 returns to the standard posture A1 by the restoring force (acting force) of the rotation limiting spring 48. Thus, in this embodiment, when each leg 22 is separated from the cargo 30, it is possible to make each leg 22 return to the standard posture A1.
[0056] It should be noted that in this embodiment, an example is described using a rotation limiting spring 48 to suppress unnecessary rotation of each leg 22, but the invention is not limited to this. For example, unnecessary rotation of each leg 22 can also be suppressed by providing a rotation limiting part that causes friction between the upper connecting part 22B of the leg 22 and the sliding bracket 46.
[0057] The above describes one embodiment of the present invention. However, the present invention is not limited to the above description. Various modifications can be made in addition to the above description without departing from its spirit.
Claims
1. A cargo support device, comprising: The base platform has a small drone mounted on top. Four legs are located on the lower side of the base, each having two abutting parts, an upper connecting part that connects the upper ends of the two abutting parts horizontally, and a lower connecting part that connects the lower ends of the two abutting parts horizontally. The two abutting parts abut against the adjacent first and second sides of the cargo as viewed from above. The four legs support the four corners of the cargo when the two abutting parts abut against the adjacent first and second sides of the cargo. Four linear guides, serving as the first support, are fixed to the lower side of the base, supporting each leg so that it can move toward the cargo side and the opposite side of the cargo; The drive unit, which moves each of the legs toward the cargo side or the opposite side of the cargo by operating, includes an actuator, a first rod, a second rod, and a linkage mechanism. The linkage mechanism includes a central link positioned below the center of the base when viewed from above, and four outer links connected to the central link. The central link has a rotating portion and four protruding arms. One end of each of the four outer links is connected to one end of one of the four protruding arms, and the other end of each of the four outer links is connected to one of the four protruding arms. A sliding bracket, wherein the actuator is fixed to the base in a position above the base, a first rod is fixed to the output shaft of the actuator, one end of a second rod is connected to the end of the first rod opposite to the output shaft, and the other end of the second rod is respectively connected to the four protruding arms of the central connecting rod, the output shaft of the actuator and the central connecting rod are connected via the first rod and the second rod, and the central connecting rod rotates in conjunction with the rotation of the output shaft of the actuator; and A second support portion is disposed between the base and each of the legs, supporting each of the legs so that they can rotate axially in the vertical direction. For cargo with a standard aspect ratio, when the central link rotates in the second direction due to the rotation of the actuator's output axis in the first direction, the four outer links pull the four sliding brackets, causing each leg to move towards the cargo. The two abutting portions of each leg abut against the adjacent first and second side surfaces, respectively. The lower connecting portions of each leg are arranged along the lower surface of the cargo, thus supporting the four corner portions of the cargo with a standard aspect ratio. The posture of each leg relative to each linear guide when the legs are not supporting the cargo is referred to as the standard posture. For a flat aspect ratio cargo whose horizontal dimension of the first side is smaller than the horizontal dimension of the first side of the cargo with a standard aspect ratio, when each of the legs moves toward the cargo side, one abutment of the leg abuts against the first side. If each of the legs moves further toward the cargo side, each of the legs rotates from the standard posture to a third side, and the other abutment of the leg abuts against the second side. When the two abutment portions of each of the legs abut against the adjacent first side and second side respectively, the lower connecting portion of each of the legs is arranged along the lower surface of the flat aspect ratio cargo, so that the four corner portions of the flat aspect ratio cargo are supported by each of the legs.
2. The cargo support device according to claim 1, wherein, The cargo support device also includes a rotation limiting part, which restricts the rotation of each leg along the vertical axis. The rotation limiting part restricts the rotation of each leg in the up-down direction as an axis when each leg is not supporting the cargo.
3. The cargo support device according to claim 2, wherein, The rotation limiting part is formed as a rotation limiting spring, and a portion of the rotation limiting spring is locked to the leg. The leg is allowed to rotate axially in the up-down direction by means of the deformation of the rotation limiting spring.
4. An unmanned cargo handling machine, comprising: Small drones; The base has the small drone mounted on its upper part; Four legs are located on the lower side of the base, each having two abutting parts, an upper connecting part that connects the upper ends of the two abutting parts horizontally, and a lower connecting part that connects the lower ends of the two abutting parts horizontally. The two abutting parts abut against the adjacent first and second sides of the cargo as viewed from above. The four legs support the four corners of the cargo when the two abutting parts abut against the adjacent first and second sides of the cargo. Four linear guides, serving as the first support, are fixed to the lower side of the base, supporting each leg so that it can move toward the cargo side and the opposite side of the cargo; The drive unit, which moves each of the legs toward the cargo side or the opposite side of the cargo by operating, includes an actuator, a first rod, a second rod, and a linkage mechanism. The linkage mechanism includes a central link positioned below the center of the base when viewed from above, and four outer links connected to the central link. The central link has a rotating portion and four protruding arms. One end of each of the four outer links is connected to one end of one of the four protruding arms, and the other end of each of the four outer links is connected to one of the four protruding arms. A sliding bracket, wherein the actuator is fixed to the base in a position above the base, a first rod is fixed to the output shaft of the actuator, one end of a second rod is connected to the end of the first rod opposite to the output shaft, and the other end of the second rod is respectively connected to the four protruding arms of the central connecting rod, the output shaft of the actuator and the central connecting rod are connected via the first rod and the second rod, and the central connecting rod rotates in conjunction with the rotation of the output shaft of the actuator; and A second support portion is disposed between the base and each of the legs, supporting each of the legs so that they can rotate axially in the vertical direction. For cargo with a standard aspect ratio, when the central link rotates in the second direction due to the rotation of the actuator's output axis in the first direction, the four outer links pull the four sliding brackets, causing each leg to move towards the cargo. The two abutting portions of each leg abut against the adjacent first and second side surfaces, respectively. The lower connecting portions of each leg are arranged along the lower surface of the cargo, thus supporting the four corner portions of the cargo with a standard aspect ratio. The posture of each leg relative to each linear guide when the legs are not supporting the cargo is referred to as the standard posture. For a flat aspect ratio cargo whose horizontal dimension of the first side is smaller than the horizontal dimension of the first side of the cargo with a standard aspect ratio, when each of the legs moves toward the cargo side, one abutment of the leg abuts against the first side. If each of the legs moves further toward the cargo side, each of the legs rotates from the standard posture to a third side, and the other abutment of the leg abuts against the second side. When the two abutment portions of each of the legs abut against the adjacent first side and second side respectively, the lower connecting portion of each of the legs is arranged along the lower surface of the flat aspect ratio cargo, so that the four corner portions of the flat aspect ratio cargo are supported by each of the legs.