Seedling planting device

Abstract

To provide a seedling planting device that can plant seedlings properly in stable states.SOLUTION: A seedling planting device 1 plants seedlings S in a ground G. The seedling planting device 1 is equipped with a detection unit 70. The detection unit 70 has a ground contact unit 71. The ground contact unit 71 is provided so as to be vertically movable and comes into contact with the ground G. The detection unit 70 detects a layer Gh of a predetermined hardness in the ground G based on the contact of the ground contact unit 71 with the ground G.SELECTED DRAWING: Figure 18

Description

[Technical Field]

[0001] The present invention relates to a seedling planting device. [Background technology]

[0002] Patent Document 1 discloses a conventional seedling planting device. This device plants seedlings in the ground. The seedlings are planted in holes formed in the ground by an auger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 171111 Summary of the Invention [Problem to be solved by the invention]

[0004] The surface of the ground where the seedlings are to be planted may have a soft layer of humus or the like formed thereon, making it difficult to stably fix the seedlings planted in the soft layer on the ground surface.

[0005] The present invention has been made in consideration of the above-mentioned conventional situation, and an object to be achieved is to provide a seedling planting device that can plant seedlings in a stable and satisfactory state. [Means for solving the problem]

[0006] The seedling planting device according to the present invention plants seedlings in the ground. The seedling planting device includes a detection unit. The detection unit has a ground contact unit. The ground contact unit is provided so as to be freely raised and lowered and to come into contact with the ground. The detection unit detects a layer of a predetermined hardness in the ground based on the contact of the ground contact unit with the ground.

[0007] This configuration allows the seedling planting device to properly grasp the layer of the ground that is hard enough to plant seedlings in. Therefore, the seedling planting device can plant seedlings stably and effectively.

[0008] In the seedling planting device, the detection unit may have a measurement unit that measures the magnitude of the load when the contact part is lowered and pressed against the ground. In this case, the seedling planting device can easily realize a configuration that can accurately determine the layer of hardness suitable for planting seedlings.

[0009] In the seedling planting device, the ground contact portion can be raised and lowered by a fluid pressure actuator. The detection unit can have a measurement unit that measures the magnitude of fluid pressure acting on the actuator when the ground contact portion is lowered and pressed against the ground. In this case, the seedling planting device can easily realize a configuration that can accurately determine the layer of hardness suitable for planting seedlings. That is, the detection unit detects the layer of a predetermined hardness by utilizing the actuator provided for raising and lowering the ground contact portion and measuring the magnitude of fluid pressure acting on this actuator. Therefore, the seedling planting device 1 can detect the layer of a predetermined hardness with a simple configuration.

[0010] In the seedling planting device, the detection unit may have a spring that contracts in response to the magnitude of the load when the contact part is lowered and pressed against the ground, and a detection unit that detects when the spring has contracted to a predetermined length. In this case, the seedling planting device can easily achieve a configuration that can accurately determine the layer of hardness suitable for planting seedlings. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view schematically showing a seedling planting device according to a first embodiment. [Figure 2] 1 is a rear view schematically showing a seedling planting device according to a first embodiment. [Figure 3] 1 is a side view schematically showing a seedling extracting unit according to a first embodiment. FIG. [Figure 4] FIG. 1 is a plan view schematically showing a seedling extracting unit according to a first embodiment. [Figure 5] 1 is a perspective view schematically showing an example of a container used in the seedling planting device according to the first embodiment. FIG. [Figure 6] FIG. 1 is a diagram for explaining a seedling pulling device according to a first embodiment. [Figure 7] 1 is a side view schematically showing a seedling planting unit according to a first embodiment. [Figure 8] FIG. 1 is a diagram (part 1) for explaining a posture maintaining unit according to the first embodiment. [Figure 9] FIG. 10 is a diagram (part 2) for explaining the attitude maintaining unit according to the first embodiment. [Figure 10] FIG. 10 is a diagram (part 3) for explaining the attitude maintaining unit according to the first embodiment. [Figure 11] FIG. 10 is a fourth diagram for explaining the attitude maintaining unit according to the first embodiment. [Figure 12] FIG. 1 is a diagram (part 1) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 13] FIG. 10 is a diagram (part 2) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 14] FIG. 10 is a diagram (part 3) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 15] FIG. 10 is a fourth diagram for explaining the operation of the seedling planting device according to the first embodiment. [Figure 16] FIG. 5 is a diagram (part 5) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 17] FIG. 6 is a diagram (part 6) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 18] FIG. 7 is a diagram (part 7) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 19] FIG. 8 is a diagram (part 8) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 20] FIG. 9 is a diagram for explaining the operation of the seedling planting device according to the first embodiment. [Figure 21]FIG. 10 is a diagram (part 10) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 22] FIG. 11 is an eleventh diagram for explaining the operation of the seedling planting device according to the first embodiment. [Figure 23] FIG. 12 is a twelfth diagram for explaining the operation of the seedling planting device according to the first embodiment. [Figure 24] FIG. 13 is a thirteenth diagram for explaining the operation of the seedling planting device according to the first embodiment. [Figure 25] FIG. 14 is a diagram (part 14) for explaining the operation of the seedling planting device according to the first embodiment. [Figure 26] FIG. 10 is a side view schematically showing a seedling planting device according to a second embodiment. [Figure 27] FIG. 10 is a plan view schematically showing a seedling planting device according to a second embodiment. [Figure 28] FIG. 10 is a rear view schematically showing a seedling planting device according to a second embodiment. [Figure 29] FIG. 10 is a rear view schematically showing a hole forming section according to the second embodiment. [Figure 30] FIG. 10 is a plan view schematically showing a hole forming section according to a second embodiment. [Figure 31] FIG. 10 is a rear view schematically showing the planting section according to the second embodiment. [Figure 32] FIG. 10 is a plan view schematically showing a planting section according to a second embodiment. [Figure 33] 10 is a diagram (part 1) for explaining a posture maintaining unit according to the second embodiment. FIG. [Figure 34] FIG. 10 is a diagram (part 2) for explaining the attitude maintaining unit according to the second embodiment. [Figure 35] FIG. 10 is a diagram (part 1) for explaining the operation of the seedling planting device according to the second embodiment. [Figure 36] FIG. 10 is a diagram (part 2) for explaining the operation of the seedling planting device according to the second embodiment. [Figure 37] FIG. 10 is a diagram (part 3) for explaining the operation of the seedling planting device according to the second embodiment. [Figure 38]FIG. 10 is a fourth diagram for explaining the operation of the seedling planting device according to the second embodiment. [Figure 39] FIG. 5 is a diagram (part 5) for explaining the operation of the seedling planting device according to the second embodiment. [Figure 40] FIG. 6 is a diagram (part 6) for explaining the operation of the seedling planting device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] <Embodiment 1> A first embodiment of a seedling planting device according to the present invention will be described with reference to the drawings. In the following description, a self-propelled seedling planting device 1 will be exemplified as the seedling planting device according to the present invention. In addition, each of the drawings referred to in the following description is shown in a simplified form, with some components other than essential parts omitted.

[0013] In the following description, the front-to-back, left-to-right, and up-to-down directions of the seedling planting device 1 are defined based on the assumption that the direction of travel of the seedling planting device 1 traveling on a horizontal plane is the forward direction. That is, the front-to-back direction of the seedling planting device 1 is the forward direction, and the opposite direction is the backward direction. The left-to-right and up-to-down directions of the seedling planting device 1 are the directions when facing forward in the direction of travel. The X-axis, Y-axis, and Z-axis shown in each diagram represent the front-to-back, left-to-right, and up-to-down directions, respectively. The positive directions of the X-axis, Y-axis, and Z-axis are forward, left, and upward, respectively. Furthermore, in the seedling planting device 1, the roll direction is the direction around an axis extending in the front-to-back direction, and the pitch direction is the direction around an axis extending in the left-to-right direction.

[0014] The seedling planting device 1 of the first embodiment is a device for planting a seedling S in the ground G. The ground G in which the seedling S is planted is a forest or other afforestation area, and is mainly a slope. A soft layer Gs such as leaf mold may be formed on the surface of the ground G (see FIG. 1, etc.). In the ground G, the layer suitable for planting the seedling S is a layer Gh having a predetermined hardness below the soft layer Gs. This predetermined hardness is preferably, for example, approximately the same as the hardness of the root ball R of the seedling S, but is not particularly limited thereto.

[0015] As shown in FIGS. 1 and 2, the seedling planting device 1 includes a traveling unit 2, a seedling removal unit 3, and a seedling planting unit 4. The traveling unit 2 includes a vehicle body 2A, a loading platform 2B, and a crawler-type endless track (hereinafter simply referred to as a crawler) 2C. The vehicle body 2A and the loading platform 2B are each box-shaped. The vehicle body 2A and the loading platform 2B are equipped with functional units (not shown) such as an engine, a battery, a fluid pressure unit, and a control unit. Each unit of the seedling planting device 1, which will be described later, includes a fluid pressure actuator, an electric actuator, etc., and is driven and controlled by these functional units. Each unit of the seedling planting device 1 can be operated by a remote control device RC capable of wireless communication.

[0016] A pair of crawlers 2C are provided on the left and right sides of the vehicle body 2A. The crawlers 2C are wound around a drive pulley 2D and a driven pulley 2E that are rotatably supported on the vehicle body 2A. As shown in Fig. 1, the crawlers 2C are wound around the drive pulley 2D and the driven pulley 2E in the shape of an oval ring that is long in the front-rear direction in a side view.

[0017] The loading platform 2B is disposed above the vehicle body 2A. The loading platform 2B is connected to the vehicle body 2A at its lower end. The loading platform 2B is rotatable relative to the vehicle body 2A around a rotation axis A1. As a result, when the vehicle body 2A tilts due to the inclination of the ground G, the loading platform 2B can tilt in the opposite direction to the inclination of the vehicle body 2A to maintain its posture. The function of the loading platform 2B rotating around the rotation axis A1 functions as a posture maintaining unit 80 (described later). The rotation axis A1 is set as an axis extending parallel to the front-to-rear direction at the upper end of the vehicle body 2A. Seedlings S before planting are placed on the upper surface of the loading platform 2B. More specifically, a seedling removal unit 3 having a seedling placement unit 10 (described later) is disposed on the rear upper surface of the loading platform 2B. The front upper surface of the loading platform 2B is used as a loading space for loading spare seedlings S, tools for planting, and the like.

[0018] As shown in Figures 3 and 4, the seedling removal unit 3 has a seedling placement section 10, a seedling extraction device 20, and a seedling removal section 30. The seedling placement section 10 places seedlings S before planting. In this embodiment, multiple seedlings S are placed in the seedling placement section 10. The multiple seedlings S are placed in seedling-raising containers C together with the containers C in the seedling placement section 10. As shown in Figure 5, the containers C form an array of multiple cultivation holes H. Each cultivation hole H has a truncated conical shape that widens in diameter toward the top. Each seedling S extends upward from a root ball R in the cultivation hole H.

[0019] The seedling placement unit 10 can move the placed seedlings S. Specifically, the seedling placement unit 10 has a movement mechanism unit 11. The movement mechanism unit 11 moves the seedlings S placed in the seedling placement unit 10 in the front-rear direction. For example, as shown in FIGS. 3 and 4, the movement mechanism unit 11 is configured with a moving body such as a carriage that carries a container C and is movable in the front-rear direction on the top surface of the loading platform 2B. The moving body can be position-controlled so as to stop at a predetermined position by controlling the expansion and contraction amount of a fluid pressure actuator such as a cylinder, or by controlling the drive of a stepping motor, servo motor, or the like. In this way, the movement mechanism unit 11 moves the container C to an extraction position when the seedling extraction device 20 (described later) extracts the seedling S from the container C, or moves the seedling S on the container C to an extraction position when the seedling extraction unit 30 (described later) extracts the seedling S.

[0020] The seedling extraction device 20 extracts seedlings S from the cultivation holes H of the container C. As shown in Figure 6, the seedling extraction device 20 is stored in the loading platform 2B below the seedling placement section 10. The seedling extraction device 20 is configured with a plurality of fluid pressure actuators 21A, 21B, 21C, 21D and a plurality of sequence valves 22A, 22B, 22C, the number of which is one less than the plurality of actuators 21A, 21B, 21C, 21D.

[0021] The actuators 21A, 21B, 21C, and 21D are, for example, single-acting cylinders that extend using fluid pressure and return using a spring. As shown in FIG. 6, each actuator 21A, 21B, 21C, and 21D is positioned so that its rod can protrude upward. Each actuator 21A, 21B, 21C, and 21D extends using fluid pressure supplied from a fluid pressure unit (not shown) mounted on the traveling unit 2. The actuators 21A, 21B, 21C, and 21D are aligned in a row in the left-right direction below the seedling-arranging section 10. Specifically, the spacing between the actuators 21A, 21B, 21C, and 21D is the same as the spacing between the cultivation holes H aligned in the left-right direction in the container C when placed in the seedling-arranging section 10. The actuators 21A, 21B, 21C, and 21D are connected to a fluid pressure supply flow path that communicates with a fluid pressure supply source in the order 21A, 21B, 21C, and 21D from the upstream side.

[0022] As shown in Fig. 6, in the seedling extraction device 20, a plurality of sequence valves 22A, 22B, and 22C are arranged in series in a fluid pressure supply flow path. A plurality of actuators 21A, 21B, 21C, and 21D are connected to the fluid pressure supply flow path in which the plurality of sequence valves 22A, 22B, and 22C are arranged as follows: Of the plurality of actuators 21A, 21B, 21C, and 21D, one actuator 21A is connected to a flow path upstream of the sequence valve 22A arranged most upstream in the flow path. Furthermore, of the plurality of actuators 21A, 21B, 21C, and 21D, the other actuators 21B, 21C, and 21D are connected to flow paths downstream of each of the sequence valves 22A, 22B, and 22C.

[0023] Each sequence valve 22A, 22B, 22C opens when a pressure greater than the operating pressure of the actuators 21A, 21B, 21C, 21D (the pressure when generating the thrust required to extract the seedling S) acts in the primary flow path, allowing the working fluid to flow from the primary flow path to the secondary flow path. This allows the seedling extraction device 20 to sequentially extend each of the actuators 21A, 21B, 21C, 21D. The seedling extraction device 20 may also be configured with individual operating valves for each of the actuators 21A, 21B, 21C, 21D. In this case, each operating valve is controlled to open and close sequentially.

[0024] The operation of the seedling extraction device 20 is as follows. In the seedling extraction device 20, fluid pressure supplied from the fluid pressure supply source acts directly on the actuator 21A, which is connected upstream of the multiple sequence valves 22A, 22B, and 22C, causing the rod of the actuator 21A to extend. This pushes up the root ball R of the seedling S in the cultivation hole H, extracting the seedling S. When the actuator 21A reaches its extension end, the pressure in the flow path supplying fluid pressure to the actuator 21A exceeds the operating pressure of the actuator 21A. This also increases the pressure in the primary flow path of the sequence valve 22A, which is located most upstream and communicates with this flow path, causing the sequence valve 22A to open its flow path. This causes the next actuator 21B to begin extending. When the actuator 21B reaches its extension end, the next sequence valve 22B opens its flow path, and the next actuator 21C begins extending. In this way, the seedling extraction device 20 sequentially extends the actuators 21A, 21B, 21C, and 21D to sequentially extract the seedlings S from the container C. After all the seedlings S have been extracted, the supply of fluid pressure from the fluid pressure unit is stopped, and the actuators 21A, 21B, 21C, and 21D sequentially contract due to the action of the springs. Note that the container C is temporarily fixed by a fixing means (not shown) while the seedling extraction device 20 is operating. This prevents the container C from floating up or becoming displaced, even when it receives a force pushing up the seedlings S from the actuators 21A, 21B, 21C, and 21D.

[0025] Within the cultivation hole H, the root ball R of the seedling S is tightly fitted into the cultivation hole H. This makes it difficult to manually extract the seedling S from the container C. The seedling extraction device 20 can effectively apply downward pressure from the fluid pressure to the root ball R, making it easy to extract the seedling S. Because the seedling extraction device 20 extracts the seedlings S one by one, less force is required to act at one time compared to when multiple seedlings are extracted simultaneously. This reduces the load on the container C compared to when multiple seedlings are extracted at one time. The seedling extraction device 20 requires less rigidity to support the actuators 21A, 21B, 21C, and 21D compared to when multiple seedlings are extracted at one time, which simplifies the structure of the device and its surroundings.

[0026] The seedling extraction device 20 extracts only seedlings S arranged in a single row in the left-right direction. Therefore, the seedling extraction device 20 can reliably extract the seedlings S one by one using the seedling extraction unit 30, which will be described later. For example, suppose that the seedling extraction unit 30 mistakenly grasps both the seedling S to be extracted and a seedling S in the row behind it that is not to be extracted. In this case, the seedling S to be extracted is easily extracted because the root ball R has been released from the seedling extraction device 20. In contrast, the seedlings S that are not to be extracted still have their root balls R trapped inside them, and they cannot be removed even if the seedling extraction unit 30 is moved upward in an attempt to remove them. Therefore, when the seedling extraction unit 30 extracts the seedlings S, only the seedlings S to be extracted are reliably extracted, and the seedlings S that are not to be extracted are not easily extracted.

[0027] To remove the next row of seedlings S, the container C on the seedling placement unit 10 is moved by the movement mechanism 11, and the next row is placed on the seedling removal device 20. The movement mechanism 11 moves the container C backward by the arrangement pitch of the cultivation holes H in the container C. The seedling removal device 20 sequentially removes the seedlings S on the containers C that are sequentially fed in this way, row by row.

[0028] The seedling removal unit 30 removes seedlings S placed in the seedling placement unit 10. As shown in Figures 3 and 4, the seedling removal unit 30 has a support 31, a removal chuck 32, and a partition plate 33. The support 31 is erected at the rear end of the loading platform 2B. The support 31 is gate-shaped and connected to the top of the loading platform 2B at its left and right lower ends. The removal chuck 32 is supported by the support 31. The removal chuck 32 is supported by the support 31 so as to be movable up and down and left and right. The removal chuck 32 grips the seedling S. In this embodiment, the seedling S is gripped by the removal chuck 32 at the portion of the trunk exposed above the root ball R.

[0029] As shown in Figures 3 and 4, the extraction chuck 32 has a pair of left and right claws 32A and a claw support portion 32B that supports the pair of claws 32A. The pair of claws 32A can be moved left and right by a drive source (not shown). The pair of claws 32A grip the seedling S by moving symmetrically left and right to change the spacing between them. The claw support portion 32B supports the pair of claws 32A so that the spacing between them can be changed. The pair of claws 32A extend forward from the front end of the claw support portion 32B. The extraction chuck 32 is supported by a support column 31 at the claw support portion 32B. The extraction chuck 32 is rotatable around a rotation axis A2 that is parallel to the left and right direction.

[0030] When removing seedlings S from the seedling placement unit 10, the partition plate 33 is placed between the seedling S to be removed and the seedling S adjacent to the seedling S to be removed that is not to be removed. This allows the seedling removal unit 30 to untangle the branches of the seedling S that is not to be removed and the branches of the seedling S to be removed when removing the seedlings S, thereby preventing the seedling S that is not to be removed from being removed. As shown in FIGS. 3 and 4 , the partition plate 33 is positioned outside the jaw support portion 32B in the left-right direction, which is the movement direction when changing the spacing between the pair of jaws 32A, with its plate thickness direction facing the left-right direction. The front edge of the partition plate 33 is inclined relative to the up-down direction. Specifically, the front edge of the partition plate 33 is inclined backward as it extends upward. The partition plate 33 is fixed to the jaw support portion 32B of the removal chuck 32. As a result, the partition plate 33 cannot move relative to the claw support portion 32B regardless of the spacing change operation of the pair of claws 32A. In this embodiment, a pair of partition plates 33 are provided on the left and right. The pair of partition plates 33 are fixed to the front end portions of the claw support portions 32B on the outer left and right sides.

[0031] The height of the upper edge of each partition plate 33 is set to be equal to or higher than the height of the upper end of the seedling S gripped by the pair of claws 32A. Specifically, the height from the lower end to the upper end of the partition plate 33 is set to approximately 300 mm. In this embodiment, the height from the upper end of the root ball R of the seedling S is approximately 300 mm. When the pair of claws 32A properly grips the seedling S, the lower end of the partition plate 33 is located slightly higher than the upper end of the root ball R (see, for example, FIG. 11 ). Therefore, when the pair of claws 32A properly grips the seedling S, the upper end position of the partition plate 33 is equal to or higher than the upper end of the seedling S. Therefore, when the pair of claws 32A properly grips the seedling S, the partition plate 33 can effectively separate the seedling S to be removed from the adjacent seedling S that is not to be removed.

[0032] The seedling planting unit 4 plants seedlings S in the ground G. As shown in Figures 1 and 2, the seedling planting unit 4 is provided behind the traveling unit 2. The seedling planting unit 4 is movable in the up and down direction relative to the traveling unit 2. The seedling planting unit 4 is tiltable in the front and back direction relative to the traveling unit 2.

[0033] As shown in FIG. 7 , the seedling planting unit 4 includes a main slider 40, a hole forming unit 50, a planting unit 60, and a detection unit 70. The main slider 40 supports the hole forming unit 50, the planting unit 60, and the detection unit 70. The main slider 40 extends linearly in the vertical direction at the center of the seedling planting device 1 in the horizontal direction. The main slider 40 is provided to be movable in a predetermined direction. In this embodiment, the main slider 40 moves vertically. Specifically, the main slider 40 is provided relative to the traveling unit 2 to be movable vertically along a planting axis P (described later). The main slider 40 is also provided relative to the traveling unit 2 to be rotatable around a rotation axis A3 extending in the horizontal direction. In this embodiment, the rotation axis A3 is set at a position perpendicular to the rotation axis A1 extending in the front-rear direction.

[0034] The main slider 40 is supported by a slider support 41. The slider support 41 is connected to the rear end of the platform 2B of the traveling unit 2. The slider support 41 supports the main slider 40 so that it can move up and down. Specifically, the slider support 41 extends up and down and moves the main slider 40 along its extension direction. This allows the seedling planting unit 4 to move up and down as a whole. The slider support 41 also rotates around a rotation axis A3 relative to the platform 2B. This allows the seedling planting unit 4 as a whole to change its inclination angle in the front-to-rear direction relative to the ground G. When the traveling unit 2 tilts due to the inclination of the ground G, the seedling planting unit 4 can tilt in the opposite direction to the inclination of the traveling unit 2 and maintain its posture. The seedling planting unit 4's rotation around the rotation axis A3 functions as a posture maintaining unit 80, which will be described later.

[0035] The hole forming unit 50 forms a hole D (see Figure 19, etc.) in the ground G for planting a seedling S. As shown in Figure 7, the hole forming unit 50 is disposed behind the main slider 40. The hole forming unit 50 is movable up and down, which is the same direction as the movement direction of the main slider 40. The hole forming unit 50 is movably supported by a guide rail 50A. The guide rail 50A is fixedly disposed with respect to the main slider 40. The hole forming unit 50 moves up and down with respect to this guide rail 50A, and thereby moves up and down relative to the main slider 40. In other words, it can be said that the hole forming unit 50 is supported by the main slider 40 via the guide rail 50A.

[0036] The hole forming unit 50 is also movable in the front-rear direction relative to the guide rail 50A. Specifically, the hole forming unit 50 is movable between a position closer to the main slider 40, indicated by a solid line in FIG. 7, and a position on the axis P, indicated by a two-dot chain line in FIG. 7, which is a rearward position from this position. The axis P is the planting axis. The planting axis P is a virtual axis that is arbitrarily set on the seedling planting device 1. The seedling S to be planted by the seedling planting device 1 moves along this planting axis P for planting. The hole forming unit 50 moves up and down along this planting axis P. The hole forming unit 50 forms a hole D in the ground G on the planting axis P by descending along the planting axis P. The position closer to the main slider 40 is the initial position of the hole forming unit 50. Except when forming a hole D, the hole forming unit 50 retreats from its position on the planting axis P to its initial position.

[0037] As shown in FIG. 7, the hole forming unit 50 includes a drill 51, a drill shank 52, and a drill support 53. The drill 51 includes a conical portion 51A and an expanded diameter portion 51B. The conical portion 51A has a conical spiral shape and expands in diameter as it extends upward. The expanded diameter portion 51B is connected to the upper end of the conical portion 51A. The expanded diameter portion 51B has a spiral shape with an outer diameter that expands in a stepped manner from the outer diameter at the upper end of the conical portion 51A. The expanded diameter portion 51B sweeps away soil from the upper edge of the depression formed by the conical portion 51A and further forms a countersunk depression at the upper end of the depression (see FIG. 19, etc.). The drill shank 52 is connected to the upper end of the drill 51 and transmits power to the drill 51 to rotate the drill 51. The drill support portion 53 rotatably supports the drill shaft portion 52. The hole forming portion 50 is supported by the drill support portion 53 on a guide rail 50A.

[0038] The configuration of the drill is not particularly limited as long as it forms a hole in the ground. The drill may form a hole of a shape other than a cone, such as a cylindrical shape. The drill may be configured as a so-called auger drill having a cylindrical spiral shape. Furthermore, it is not essential for the drill to have an enlarged diameter portion. If the drill has an enlarged diameter portion, the configuration of the enlarged diameter portion is not particularly limited as long as it forms a counterbore-shaped recess. The enlarged diameter portion is not limited to a spiral shape and may be an impeller-shaped portion.

[0039] The planting unit 60 plants seedlings S in the holes D formed by the hole forming unit 50. As shown in FIG. 7, the planting unit 60 is disposed behind the hole forming unit 50. The planting unit 60 is movable up and down, which is the same direction as the movement direction of the main slider 40. Specifically, the planting unit 60 is supported by a guide rail 60A so as to be movable up and down along the planting axis P. The guide rail 60A is fixedly disposed relative to the main slider 40. As a result, the planting unit 60 moves up and down relative to the guide rail 60A, and therefore also moves up and down relative to the main slider 40. In other words, the planting unit 60 is supported by the main slider 40 via the guide rail 60A.

[0040] As shown in FIG. 7, the planting unit 60 includes a planting chuck 61 and a chuck support 62. The planting chuck 61 includes a pair of left and right claws 61A whose spacing can be adjusted, and a claw support 61B that supports the claws 61A so that the spacing can be adjusted. When the pair of claws 61A is spaced the shortest, they form a cylindrical shape with a bottom wall at their lower ends. Furthermore, when the pair of claws 61A is spaced the shortest, the bottom wall defines a through-hole (not shown) through which the root ball R cannot pass but the trunk of the seedling S can pass. The bottom wall formed by the pair of claws 61A can be lowered after planting the seedling S to compact the root ball R and the soil around the root ball R with its bottom surface. The chuck support 62 supports the planting chuck 61. The planting unit 60 is supported by the chuck support 62 on a guide rail 60A. The seedling S chucked by the planting chuck 61 is lowered on the planting axis P shown in FIG. 7 and other figures and planted.

[0041] The detection unit 70 detects a layer Gh of a predetermined hardness on the ground G. As described above, the layer Gh of a predetermined hardness is a layer on the ground G that has a hardness suitable for planting a seedling S. On the ground G, it is difficult to stably fix a seedling S in a soft layer Gs such as leaf mold on the surface. Therefore, the seedling planting device 1 uses the detection unit 70 to detect a layer Gh of a hardness suitable for planting a seedling S, and plants the seedling S in this layer Gh. The hardness suitable for planting a seedling S is, for example, a hardness equivalent to that of the root ball R of the seedling S.

[0042] The detection unit 70 has a ground contact portion 71 and a load cell (not shown). The load cell corresponds to the measurement unit according to the present invention. The ground contact portion 71 comes into contact with the ground G. The detection unit 70 detects a layer Gh of a predetermined hardness on the ground G based on the contact of the ground contact portion 71 with the ground G. As shown in FIG. 7 , the ground contact portion 71 is provided on the lower part of the main slider 40. The ground contact portion 71 extends downward in a rod shape from the lower end of the main slider 40. The ground contact portion 71 comes into contact with the ground G as the main slider 40 descends. The main slider 40 continues to descend until the lower end of the ground contact portion 71 reaches the layer Gh of the predetermined hardness on the ground G.

[0043] The load cell measures the magnitude of the load when the ground contact portion 71 is pressed against the ground G. As a result, when the detection unit 70 measures the magnitude of the load corresponding to the magnitude when the ground contact portion 71 is pressed against a layer Gh of a predetermined hardness, it can detect the layer at that depth as a layer of the predetermined hardness.

[0044] The detection of the layer of a predetermined hardness is not limited to the use of the load cell. For example, the detection of the layer of a predetermined hardness may be performed using a configuration including a spring that contracts in response to the magnitude of the load when the contact portion is lowered and pressed against the ground, a detection object such as a magnetic member or a dog plate that changes position as the spring contracts, and a detection unit that detects the change in position of the detection object and detects when the spring has contracted to a predetermined length, such as a non-contact or contact switch. Alternatively, the detection may be performed by calculating the magnitude of the thrust when the contact portion is lowered and pressed against the ground from the load of the thrust generating means, and detecting the layer of a predetermined hardness based on this. In this case, the thrust generating means may be, for example, a fluid pressure actuator or an electric actuator.

[0045] The seedling planting device 1 is equipped with a posture maintaining unit 80. The posture maintaining unit 80 maintains the posture of each of the seedling take-out unit 3 and the seedling planting unit 4. The seedling planting device 1 is used on sloping ground such as a mountain forest. In this case, the seedling planting device 1 tilts in accordance with the slope of the ground G. It is preferable that the take-out of seedlings S by the seedling take-out unit 3 and the planting of seedlings S by the seedling planting unit 4 be performed in a constant posture regardless of the slope caused by the slope of the ground G, etc. The seedling planting device 1 maintains each of the seedling take-out unit 3 and the seedling planting unit 4 in a predetermined posture using the posture maintaining unit 80. This allows the seedling planting device 1 to stabilize the take-out of seedlings S by the seedling take-out unit 3 and the planting of seedlings S by the seedling planting unit 4.

[0046] In this embodiment, the position maintaining section 80 maintains the position of the seedling removal unit 3 and the seedling planting unit 4 in the position where the seedling planting device 1 shown in Figures 1 and 2 is on a horizontal plane (hereinafter also referred to as the horizontal position). In this horizontal position, the seedling S on the seedling placing section 10 is placed in a position extending vertically upward from the root ball R. In addition, in the horizontal position, the planting axis P of the seedling planting unit 4 is vertical.

[0047] As shown in Figures 8 to 11, the posture maintaining unit 80 has a first tilt adjustment unit 81 and a second tilt adjustment unit 82. Note that the seedling planting device 1 shown in Figures 8 to 11 has been simplified by omitting some of the components other than the essential parts. The tilt of the seedling extraction unit 3 in the left-right direction (roll direction) is adjusted by the first tilt adjustment unit 81. The tilt of the seedling planting unit 4 in the left-right direction and the front-back direction (pitch direction) is adjusted by the first tilt adjustment unit 81 and the second tilt adjustment unit 82. The posture maintaining unit 80 has detection means (not shown) that can detect tilt, such as a tilt sensor, acceleration sensor, or angular velocity sensor, and maintains posture based on the detection results of this detection means.

[0048] The first tilt adjustment unit 81 rotates the bed 2B in the roll direction relative to the vehicle body 2A. That is, the first tilt adjustment unit 81 adjusts the tilt of the bed 2B in the roll direction relative to the vehicle body 2A. The second tilt adjustment unit 82 rotates the slider support unit 41 in the pitch direction relative to the bed 2B. That is, the second tilt adjustment unit 82 adjusts the tilt of the slider support unit 41 in the pitch direction relative to the bed 2B.

[0049] 8 and 9, the first tilt adjustment unit 81 has a first pivotal support portion 81A, a vehicle body side bracket 81B, a bed side first bracket 81C, and a first cylinder 81D. The first pivotal support portion 81A supports rotation of the bed 2B relative to the vehicle body 2A about a rotation axis A1. The first pivotal support portion 81A connects a vehicle body side pivotal support member 81A1 and a bed side first pivotal support member 81A2 so that they can rotate freely relative to each other about the rotation axis A1. The vehicle body side pivotal support member 81A1 protrudes upward from the top surface of the box-shaped vehicle body 2A at the center in the left-right direction of the vehicle body 2A.

[0050] As shown in FIGS. 8 and 9, the platform-side first pivotal support member 81A2 is provided at the lower end of the platform 2B. Specifically, the platform 2B has a top plate 91 on whose upper surface the seedling removal unit 3 is disposed, and top plate support members 92, 93 extending downward from the top plate 91. The platform-side first pivotal support member 81A2 is connected to the lower ends of the top plate support members 92, 93. In this embodiment, a pair of left and right top plate support members 92, 93 are provided. These pair of top plate support members 92, 93 extend downward from both left and right ends of the top plate 91 toward the center in a V-shape. One of the pair of top plate support members 92, 93, the top plate support member 92, is formed with a through-hole 92A. The first cylinder 81D passes through this through-hole 92A of the top plate support member 92. The other top plate support member 93 has a loading-carrying ...

[0051] The vehicle body side bracket 81B is fixed to the vehicle body 2A at a position a predetermined distance L1 away from the first pivotal support portion 81A. The vehicle body side bracket 81B pivotally supports one end of the first cylinder 81D so that it can rotate freely around a rotation axis A4. This rotation axis A4 is an axis parallel to the rotation axis A1. In this embodiment, the rotation axis A4 is provided at a position separated from the first pivotal support portion 81A in the left-right direction.

[0052] The bed-side first bracket 81C is fixed to the bed 2B at a position that is a predetermined distance L2 away from the first pivot support portion 81A. The fixed position of this bed-side first bracket 81C with respect to the bed 2B is a position that is a predetermined angle d1 away from the vehicle-body-side bracket 81B around the rotation axis A1. The magnitudes of these predetermined distances, angles, etc. are not particularly limited as long as they can function as a first tilt adjustment unit that adjusts the tilt of the bed 2B in the roll direction relative to the vehicle body 2A.

[0053] In this embodiment, the loading platform side first bracket 81C is fixed to a top plate support member 93, which is one of a pair of top plate support members 92, 93 on the loading platform 2B. The loading platform side first bracket 81C supports the other end of the first cylinder 81D rotatably about a rotation axis A5. This rotation axis A5, like the rotation axis A4, is an axis parallel to the rotation axis A1. In this embodiment, the rotation axis A5 is provided at a position spaced apart from the first pivot support portion 81A in the up-down direction.

[0054] The predetermined distance L1 between the first shaft support portion 81A and the vehicle-side bracket 81B is the distance between the rotation axis A1 and the rotation axis A4. The predetermined distance L2 between the first shaft support portion 81A and the platform-side first bracket 81C is the distance between the rotation axis A1 and the rotation axis A5. The predetermined angle d1 around the rotation axis A1 between the platform-side first bracket 81C and the vehicle-side bracket 81B is the angle between the rotation axis A4 and the rotation axis A5. The predetermined angle around the rotation axis A1 between the platform-side first bracket 81C and the vehicle-side bracket 81B is the angle in the neutral state. Note that the neutral state is a state in which the seedling planting device 1 is on a horizontal plane. In this state, the various parts of the seedling planting device 1 are in the following states: the crawler 2C of the traveling unit 2 is horizontally in contact with the ground G, the seedling removal unit 3 on the platform 2B is in a horizontal position, and the planting axis P of the seedling planting unit 4 is vertical. The angle between the first bracket 81C on the loading platform side and the bracket 81B on the vehicle body side changes as the first cylinder 81D expands and contracts. In the seedling planting device 1, the range of this angle change is set to about ±40°.

[0055] As shown in FIGS. 8 and 9, the first cylinder 81D has both ends connected to the vehicle body bracket 81B and the bed-side first bracket 81C. The first cylinder 81D extends and retracts between the vehicle body bracket 81B and the bed-side first bracket 81C. This allows the first cylinder 81D to rotate the bed 2B around the rotation axis A1 relative to the vehicle body 2A. Specifically, the first cylinder 81D is rotatably supported at its bottom end by the vehicle body bracket 81B and at its head end by the bed-side first bracket 81C. The first cylinder 81D changes the angle around the rotation axis A1 between the vehicle body bracket 81B and the bed-side first bracket 81C (the angle between the rotation axis A4 and the rotation axis A5) within a range of ±40° as it extends and retracts from its neutral length. That is, the first tilt adjustment unit 81 can adjust the tilt of the platform 2B relative to the vehicle body 2A in the roll direction within a range of ±40° by extending or contracting the first cylinder 81D.

[0056] In this embodiment, the first cylinder 81D is positioned so as to overlap the top plate support members 92, 93 in the direction of the rotation axis A1 (front-rear direction). The first cylinder 81D passes through a through-hole 92A formed in the top plate support member 92 and is connected to a platform-side first bracket 81C fixed to the top plate support member 93 and a vehicle-body-side bracket 81B fixed to the vehicle body 2A. This configuration allows the first tilt adjustment unit 81 to realize an ideal positioning of the first cylinder 81D, which can apply sufficient biasing force for rotation with an appropriate stroke while minimizing the size in the front-rear direction, up-down direction, etc. As described above, both ends of the first cylinder 81D are supported by the vehicle-body-side bracket 81B and the platform-side first bracket 81C. The vehicle-body-side bracket 81B is positioned in the left-right direction perpendicular to the rotation axis A1 from the first pivot support portion 81A. Ideally, the bed-side first bracket 81C is positioned vertically perpendicular to the rotation axis A1 at the same position as the vehicle-side bracket 81B in the fore-aft direction. That is, the bed-side first bracket 81C and the vehicle-side bracket 81B are ideally positioned in the same plane perpendicular to the rotation axis A1. Ideally, the bed-side first bracket 81C is directly fixed to a member positioned in the same plane. Furthermore, when converting the extension and retraction of the cylinder into rotational motion, ensuring an ideal amount of extension and retraction of the cylinder relative to the rotation angle requires a certain distance between the vehicle-side bracket 81B and the bed-side first bracket 81C. To achieve this, the inventors conceived of positioning the vehicle-side bracket 81B on the vehicle body 2A farthest from the first pivot support portion 81A and positioning the bed-side first bracket 81C on the top panel support member 93 based on this position. However, in the case of the seedling planting device 1 according to this embodiment, the placement of the cylinder was difficult due to the placement of the top plate support member 92, which is the other member supporting the top plate 91. In response to this, the inventors of the present application formed a through-hole 92A in the top plate support member 92 and configured the first cylinder 81D to pass through this through-hole 92A. This enabled the seedling planting device 1 to realize the first tilt adjustment unit 81 with the first cylinder 81D ideally positioned.

[0057] The posture maintaining unit 80 maintains the horizontal posture of the platform 2B in the roll direction, thereby maintaining the horizontal posture of each of the seedling removal unit 3 and the seedling planting unit 4 in the roll direction. For example, as shown in FIG. 10, assume that the seedling planting device 1 is on a slope with a valley to the left and a mountain to the right. In this case, the vehicle body 2A of the traveling unit 2 tilts in accordance with the slope. In this state, the platform 2B is tilted to the left with respect to the vehicle body 2A by the first tilt adjustment unit 81, maintaining the horizontal posture in the roll direction. The platform 2B has a rotation axis A1 set at its lower end, which is the connecting portion with the vehicle body 2A. Therefore, the portion of the platform 2B above the rotation axis A1 moves closer to the mountain side due to tilting around the rotation axis A1 by the first tilt adjustment unit 81. This shifts the center of gravity of the platform 2B toward the mountain side. Therefore, the seedling planting device 1 has an improved tipping limit angle, making it less likely to tip over.

[0058] As shown in Figures 8 and 9, the second tilt adjustment unit 82 has a second pivotal support unit 82A, a platform-side second bracket 82B, a slider support unit-side bracket 82C, and a second cylinder 82D. The second pivotal support unit 82A supports rotation of the slider support unit 41 relative to the platform 2B about a rotation axis A3. The second pivotal support unit 82A connects a platform-side second pivotal support member 82A1 and a slider support unit-side pivotal support member 82A2 so that they can rotate freely relative to each other about the rotation axis A3. The platform-side second pivotal support member 82A1 protrudes rearward from the platform-side first pivotal support member 81A2 of the first pivotal support unit 81A. The slider support unit-side pivotal support member 82A2 is provided at the lower end of the slider support unit 41 and protrudes forward.

[0059] The bed-side second bracket 82B is fixed to the bed 2B at a position a predetermined distance L3 away from the second pivotal support portion 82A. The bed-side second bracket 82B pivotally supports one end of the second cylinder 82D so that it can rotate freely around a rotation axis A6. This rotation axis A6 is an axis parallel to the rotation axis A3.

[0060] The slider support unit side bracket 82C is fixed to the slider support unit 41 at a predetermined distance L4 from the second pivot support unit 82A. The fixed position of the slider support unit side bracket 82C relative to the slider support unit 41 is a predetermined angle d2 away from the platform side second bracket 82B around the rotation axis A3. In this embodiment, the slider support unit side bracket 82C supports the other end of the second cylinder 82D rotatably around the rotation axis A7. Like the rotation axis A6, the rotation axis A7 is an axis parallel to the rotation axis A3. The magnitudes of the predetermined distance, the predetermined angle, and the like are not particularly limited as long as the second tilt adjustment unit can function to adjust the tilt of the slider support unit 41 in the pitch direction relative to the platform 2B.

[0061] The predetermined distance L3 between the second pivot support portion 82A and the platform-side second bracket 82B is the distance between the rotation axis A3 and the rotation axis A6. The predetermined distance L4 between the second pivot support portion 82A and the slider support unit-side bracket 82C is the distance between the rotation axis A3 and the rotation axis A7. The predetermined angle d2 around the rotation axis A3 between the slider support unit-side bracket 82C and the platform-side second bracket 82B is the angle between the rotation axis A6 and the rotation axis A7. The predetermined angle d2 around the rotation axis A3 between the slider support unit-side bracket 82C and the platform-side second bracket 82B is the angle in the neutral state. In this neutral state, the planting axis P of the seedling planting unit 4 is vertical. The angle between the slider support unit-side bracket 82C and the platform-side second bracket 82B changes due to the extension and contraction of the second cylinder 82D. In the seedling planting device 1, the range of this angle change is set to approximately ±40°.

[0062] As shown in FIGS. 8 and 9, the second cylinder 82D is connected at both ends to the platform-side second bracket 82B and the slider support unit-side bracket 82C. The second cylinder 82D extends and retracts between the platform-side second bracket 82B and the slider support unit-side bracket 82C. This allows the second cylinder 82D to apply a biasing force to the slider support unit 41, causing it to rotate around the rotation axis A3 relative to the platform 2B. Specifically, the bottom end of the second cylinder 82D is rotatably supported by the platform-side second bracket 82B, and the head end of the second cylinder 82D is rotatably supported by the slider support unit-side bracket 82C. The extension and retraction of the second cylinder 82D from its neutral length changes the angle around the rotation axis A3 between the platform-side second bracket 82B and the slider support unit-side bracket 82C (the angle between the rotation axis A6 and the rotation axis A7) within a range of ±40°. That is, the second tilt adjustment section 82 can adjust the tilt of the slider support section 41 relative to the deck 2B within a range of ±40° in the pitch direction by extending and retracting the second cylinder 82D.

[0063] The posture maintaining unit 80 maintains the horizontal posture of the seedling planting unit 4 in the pitch direction. For example, as shown in FIG. 11, assume that the seedling planting device 1 is on a slope with a valley in front and a mountain in rear. In this case, the vehicle body 2A of the traveling unit 2 tilts in accordance with the slope, and the platform 2B connected to the vehicle body 2A also tilts in a similar manner. In this state, the slider support unit 41 tilts rearward relative to the platform 2B by the second tilt adjustment unit 82, maintaining the horizontal posture in the pitch direction. The seedling planting unit 4 maintains the verticality of the planting axis P by adjusting the tilt in the roll direction by the first tilt adjustment unit 81 and the tilt in the pitch direction by the second tilt adjustment unit 82. The seedling S planted by the seedling planting unit 4, whose posture is maintained in this manner, maintains a vertical posture regardless of the degree of inclination of the ground G. In this way, the posture maintaining section 80 maintains the posture of the seedling planting unit 4 so that the planting axis P remains vertical. The posture maintaining section 80 maintains the posture of the seedling planting unit 4 so that not only the planting axis P is vertical, but also the movement directions of the main slider 40, hole forming section 50, and planting section 60 are vertical.

[0064] Next, the operation of the seedling planting device 1 configured as described above will be described. When using the seedling planting device 1 to plant seedlings S, a user of the seedling planting device 1 first places the seedlings S in the seedling placing section 10. The seedling planting device 1 can place multiple seedlings S in containers C in the seedling placing section 10 while the containers C are still in place. In addition to the containers C to be placed in the seedling placing section 10, the seedling planting device 1 can also load spare containers C in the space at the front of the top surface of the loading platform 2B. The seedlings S in the containers C placed in the seedling placing section 10 have their root balls R removed from the cultivation holes H by the seedling removal device 20. As described above, the seedling removal device 20 sequentially removes the root balls R of the seedlings S that are set in the cultivation holes H of the containers C one by one, row by row. The seedlings S removed from the cultivation holes H are placed back into the cultivation holes H in a state where they can be easily removed. In this state, the seedling S waits to be picked up by the seedling picking unit 30.

[0065] Next, the user of the seedling planting device 1 moves the seedling planting device 1 to the planting location of the seedling S. The seedling planting device 1 travels using a pair of left and right crawlers 2C, making it extremely capable of traversing adverse terrain such as mountain forests. The seedling planting device 1 can be moved by operating the remote control device RC. The seedling planting device 1 does not require a passenger space, making it easy to reduce its size. For example, the seedling planting device according to the present invention can easily be made large enough to fit into the bed of a light vehicle-standard truck. The seedling planting device 1 can travel while maintaining the postures of the bed 2B, seedling removal unit 3, and seedling planting unit 4 using the posture maintaining unit 80. This allows the seedling planting device 1 to travel stably even on sloping ground.

[0066] Once the seedling planting device 1 has been moved to the planting location of the seedling S, the user of the seedling planting device 1 begins planting the seedling S using the seedling planting device 1. The seedling planting device 1 can automatically perform a series of operations from removing the seedling S from the seedling placement unit 10 to planting it in the ground G. Immediately before planting of the seedling S begins, the seedling removal unit 3 and seedling planting unit 4 of the seedling planting device 1 are each in a state where their postures are maintained by the posture maintaining unit 80.

[0067] Immediately before the start of planting the seedlings S, each of the movable parts of the seedling planting device 1 is positioned at its initial position. Specifically, the seedling placement unit 10 has the container C on the moving mechanism unit 11 positioned at the front end of its range of movement in the front-rear direction (see FIGS. 1, 3, 12, etc.). The initial position of the seedling removal unit 30 is such that the removal chuck 32 is positioned at the top end in the vertical direction and behind the seedling S to be removed in the left-right direction (see FIGS. 1, 2, etc.). The initial positions of the seedling planting unit 4 are such that the main slider 40, the hole forming unit 50, and the planting unit 60 are positioned at the top ends of their respective ranges of movement in the vertical direction (see FIGS. 1, 2, 7, etc.). The initial position of the hole forming unit 50 is the front end position of its range of movement in the front-rear direction (see FIGS. 1, 7, etc.).

[0068] When planting a seedling S, the seedling planting device 1 first removes the seedling S from the seedling arrangement unit 10. Removal of the seedling S from the seedling arrangement unit 10 is performed by the seedling removal unit 30. To remove the seedling S, as shown in FIG. 10 , the seedling removal unit 30 lowers the removal chuck 32 to the height of the trunk of the seedling S on the container C by a movement mechanism (not shown) of the support 31 that movably supports the removal chuck 32. In the seedling planting device 1, the seedling S removed by the removal chuck 32 is the rearmost seedling S of the seedlings S remaining on the container C, and is the leftmost seedling S of the rearmost seedling S. The removal chuck 32 moves left and right by a movement mechanism (not shown) of the support 31, and waits directly behind the seedling S to be removed. Note that the seedling S to be removed at this time may also be the rightmost seedling S of the rearmost seedlings S. It is preferable that the seedling S to be removed be adjacent to a seedling S that is not the target of removal on only one side, either the left or right.

[0069] Next, as shown in FIG. 13 , the seedling placing unit 10 moves the container C backward using the movement mechanism 11. As a result, the seedling S to be removed from the multiple seedlings S on the container C is placed between the pair of claws 32A of the removal chuck 32. The seedling removal unit 30 grips the trunk of the seedling S with the pair of claws 32A of the removal chuck 32. After the removal chuck 32 grips the seedling S, the seedling removal unit 30 raises the removal chuck 32 together with the seedling S to the upper end using a movement mechanism (not shown) of the support 31, as shown in FIG. 12 . As a result, the seedling S is removed from the seedling placing unit 10. When removing the seedling S from the cultivation hole H of the container C, the seedling planting device 1 uses the seedling removal device 20 to previously disengage the root ball R from being trapped. This allows the seedling removal unit 30 to easily remove the seedling S from the cultivation hole H of the container C. As shown in FIG. 15, the container C from which the seedling S to be removed has been removed is returned to the front by the movement mechanism 11 in preparation for the next seedling S to be removed.

[0070] When the removal chuck 32 grips the seedling S, the partition plate 33 in the seedling removal unit 30 moves between the seedling S to be removed and the adjacent seedling S that is not the target of removal, separating the seedlings S, as the seedling S moves due to the retraction of the container C. As described above, the seedlings S to be removed are seedlings S housed in the cultivation holes H of the container C, with the root balls R already removed by the seedling removal device 20. The root balls R are removed for each row of the cultivation holes H in the container C in the left-right direction. Therefore, the seedlings S adjacent to the seedling S to be removed in the left-right direction have already had their root balls R removed by the seedling removal device 20. However, because the seedling removal unit 30 has the partition plate 33, when gripping the seedling S with the pair of claws 32A, the partition plate 33 can move between the seedling S to be removed and the adjacent seedling S that is not the target of removal. As a result, even if the branches of a seedling S that is not the target of removal are entangled around the seedling S that is the target of removal, the entanglement can be untangled. Therefore, the seedling removal unit 30 can properly hold only the seedling S that is the target of removal.

[0071] The partition plate 33 is fixed to the claw support portion 32B, and does not change position in accordance with the gripping action of the pair of claws 32A. Therefore, the partition plate 33 can effectively maintain the separation between the seedlings S to be removed and the seedlings S that are not to be removed. The front edge of the partition plate 33 is formed to be inclined backward as it extends upward. Therefore, the partition plate 33 can easily enter between adjacent seedlings S while sweeping branches upward with the inclination of the front edge.

[0072] Here, consider a case where the pair of claws 32A of the seedling extraction unit 30 grabs the seedling S to be extracted and the branches of a seedling S adjacent to the rear (front) of the seedling S that is not the target seedling S, or where the branches of the adjacent seedling S that is not the target seedling S are entangled around the seedling S to be extracted. In this case, the seedling extraction unit 30 attempts to extract both the seedlings S that are not the target seedlings and the seedlings S that are not the target seedlings. However, in the case of the seedling planting device 1, as described above, the seedling extraction device 20 does not extract seedlings S in other rows until the seedling extraction unit 30 has completed the extraction of all seedlings S in one row. Therefore, the seedlings S that are not the target seedlings and the seedlings S adjacent to the target seedling S are not yet freed from the root ball R at this point. Therefore, the seedlings S that are not the target seedlings are not easily extracted, and only the target seedlings S can be successfully extracted. In this way, the seedling planting device 1 can effectively prevent the seedling extracting unit 30 from erroneously extracting a seedling S that is not the target for extraction.

[0073] As described above, in the seedling planting device 1, the seedling S that is removed by the removal chuck 32 is the seedling S in the rearmost row of the seedlings S remaining on the container C, and is the seedling S located at the leftmost end of the row. Therefore, no matter which seedling S is to be removed, there will be no seedling S adjacent to it to the left that is not to be removed. In such a case, it is not necessary to provide a pair of partition plates 33 on the left and right, and it is sufficient to provide only one partition plate on the right side. In other words, it is sufficient to provide at least one partition plate.

[0074] Next, as shown in Figure 16, the seedling planting device 1 transfers the seedling S taken out by the seedling take-out section 30 to the planting section 60 in the seedling planting unit 4. Specifically, the seedling S, while held by the take-out chuck 32, rises to the upper end position of the take-out chuck 32 and moves to the center position in the left-right direction. In other words, the seedling S taken out from the seedling placing section 10, while held by the take-out chuck 32, moves as the take-out chuck 32 moves to its initial position. Thereafter, the seedling take-out section 30 rotates the take-out chuck 32 around the rotation axis A2.

[0075] In this state, the seedling planting device 1 tilts the seedling planting unit 4 around the rotation axis A3 in accordance with the tilt of the take-out chuck 32. That is, when the seedling S is handed over, the seedling planting unit 4 is tilted by the second tilt adjustment part 82 of the posture holding part 80. After tilting the seedling planting unit 4 around the rotation axis A3, the seedling planting device 1 lowers the take-out chuck 32 toward the planting chuck 61 of the tilted planting part 60, bringing the seedling S closer to the planting chuck 61. The planting chuck 61 then grips the root ball R of the seedling S held by the take-out chuck 32. In this way, the seedling S is handed over from the take-out chuck 32 gripping the trunk to the planting chuck 61 gripping the root ball R. The take-out chuck 32 then rises and returns to its initial position. Furthermore, the seedling planting unit 4, which has received the seedling S from the seedling take-out unit 3, rotates around the rotation axis A3 and returns to an upright position, as shown in FIG.

[0076] The seedling planting unit 4 forms a hole D using the hole forming unit 50 and plants a seedling S in this hole D. Before the hole forming unit 50 forms the hole D, the seedling planting unit 4 detects a layer Gh of a predetermined hardness on the ground G using the detection unit 70. Specifically, as shown in FIG. 18 , the seedling planting unit 4 lowers the main slider 40 to press the ground contact portion 71 of the detection unit 70 against the ground G. The lowering of the main slider 40 causes the ground contact portion 71 to penetrate a soft layer Gs on the surface of the ground G and press until it reaches the layer Gh of the predetermined hardness. The seedling planting unit 4 stops the lowering of the main slider 40 when the magnitude of the load measured based on a load cell (not shown) in the detection unit 70 reaches a magnitude indicated by the predetermined hardness.

[0077] Thereafter, the seedling planting unit 4 forms a hole D using the hole forming unit 50. The hole forming unit 50 forms a hole D in the ground G on the planting axis P. Specifically, as shown in FIG. 19, the hole forming unit 50 moves backward from the initial position to the planting axis P. Then, as shown in FIG. 20, the hole forming unit 50 descends along the planting axis P. At this time, the planting axis P is kept vertical by the posture maintaining unit 80 maintaining the posture of the seedling planting unit 4. Therefore, the formed hole D is formed along the vertical direction regardless of the degree of inclination of the ground G.

[0078] The amount of descent of the hole forming unit 50 is based on the depth of a layer Gh of a predetermined hardness in the ground G. The seedling planting unit 4 lowers the hole forming unit 50 by a predetermined fixed amount of descent while the ground contact portion 71 is in contact with the ground G. This allows the seedling planting unit 4 to form holes D with the same depth in the layer Gh of a predetermined hardness, even in different planting locations, without using a means for measuring the amount of descent, such as an encoder. Furthermore, when the hole forming unit 50 forms the hole D, the ground contact portion 71 is maintained in contact with the ground G. This allows the hole forming unit 50 to form the hole D in a stable state. After forming the hole D, the hole forming unit 50 then rises and moves forward to return to its initial position, as shown in FIG. 21 .

[0079] The hole forming unit 50 forms the hole D using a drill 51 having a conical portion 51A and an enlarged diameter portion 51B. As shown in Fig. 21, the drill 51 forms a conical depression that can adequately accommodate the root ball R of the seedling S, and also forms the hole D by removing the topsoil around the upper edge of the conical depression. In this way, the hole forming unit 50 can form the hole D that is suitable for planting the seedling S.

[0080] After the hole D is formed by the hole forming section 50, the planting section 60 plants the seedling S in the hole D. Even when the planting section 60 plants the seedling S in the hole D, the seedling planting unit 4 maintains a state in which the ground contact section 71 is in contact with the ground G, and the horizontal position is also maintained by the position maintaining section 80. Therefore, the planting section 60 can plant the seedling S in the hole D in a stable state.

[0081] As shown in Figure 22, the planting section 60 lowers the seedling S held by the planting chuck 61 to just above the hole D. At this time, the amount of lowering of the planting section 60 is determined based on the depth of a layer Gh of a predetermined hardness in the ground G, similar to the amount of lowering of the hole forming section 50. Therefore, by lowering the planting section 60 by a preset fixed amount of lowering, the seedling planting unit 4 can lower the seedling S to a position at approximately the same height relative to the hole D, even in different planting locations, without using a means for measuring the amount of lowering, such as an encoder.

[0082] Next, the planting unit 60 releases its grip on the seedling S and drops the seedling S into the hole D. As a result, the root ball R of the seedling S is placed in the hole D, as shown in FIG. 23. At this time, the planting axis P is maintained vertically by the action of the posture maintaining unit 80, so the seedling S is placed in the hole D in a good posture. Thereafter, as shown in FIG. 24, the planting chuck 61 descends with the pair of jaws 61A narrowed, thereby compacting the root ball R and the soil around the root ball R with the bottom surfaces of the jaws 61A. As a result, the seedling S is planted well in the ground G, as shown in FIG. 25. Finally, the planting chuck 61 is raised and returned to its initial position, and the main slider 40 is raised and returned to its initial position. In this way, the planting of the seedling S on the planting axis P into the ground G is completed.

[0083] As described above, the seedling planting device 1 according to the first embodiment plants a seedling S in the ground G. The seedling planting device 1 includes a detection unit 70. The detection unit 70 has a ground contact unit 71. The ground contact unit 71 is provided so as to be movable in the vertical direction and comes into contact with the ground G. The detection unit 70 detects a layer Gh of a predetermined hardness in the ground G based on the contact of the ground contact unit 71 with the ground G.

[0084] With this configuration, the seedling planting device 1 can properly grasp the layer Gh of the ground G that has a hardness suitable for planting the seedling S. As a result, the seedling planting device 1 can properly plant the seedling S.

[0085] In the seedling planting device 1, the ground contact portion 71 is provided on the lower part of the main slider 40, and contacts the ground G by lowering the main slider 40. Therefore, the seedling planting device 1 can easily achieve a configuration in which the seedling S is planted at a constant depth in the layer Gh of a predetermined hardness. That is, the seedling planting device 1 has the hole forming unit 50 and the planting unit 60 movable vertically relative to the main slider 40 on which the ground contact portion 71 is provided. Therefore, the seedling planting device 1 can form holes D of the same depth in the layer Gh of a predetermined hardness, even in different planting locations, without using a descent amount measuring device such as an encoder. Furthermore, by lowering the planting unit 60 into the hole D by a predetermined fixed amount, the seedling S can be lowered to a substantially equal height relative to the hole D. As a result, the seedling planting device 1 can easily achieve planting of the seedling S at a constant depth based on the depth of the layer Gh of a predetermined hardness in the ground G.

[0086] In the seedling planting device 1, the detection unit 70 has a load cell (not shown) as a measurement unit that measures the magnitude of the load when the contact portion 71 is lowered and pressed against the ground G. Therefore, the seedling planting device 1 can easily realize a configuration that can accurately grasp the layer Gh in the ground G that has a hardness suitable for planting the seedling S.

[0087] The seedling planting device 1 according to the first embodiment also includes a vehicle body 2A and crawlers 2C as traveling units, a seedling placement unit 10, a seedling removal unit 30, and a posture maintaining unit 80. The vehicle body 2A travels on the ground G using the crawlers 2C. The seedling placement unit 10 places seedlings S before planting. The seedling removal unit 30 removes the seedlings S from the seedling placement unit 10. When the vehicle body 2A and crawlers 2C are on a horizontal plane, the posture maintaining unit 80 maintains the seedling placement unit 10 and the seedling removal unit 30 in a horizontal posture when the vehicle body 2A and crawlers 2C are on an inclined ground G.

[0088] With this configuration, the seedling planting device 1 can stably perform planting work. In particular, the seedling planting device 1 can stably perform the removal of seedlings S from the seedling placing unit 10 by the seedling removal unit 30. The seedling planting device 1 is provided with the posture maintaining unit 80, so that even if the device tilts due to a slope of the ground G, the postures of the seedling placing unit 10 and the seedling removal unit 30 are maintained in a predetermined posture. This allows the seedling placing unit 10 and the seedling removal unit 30 to stably remove seedlings S and prevent the seedlings S from falling, regardless of the degree of slope of the ground G, when removing seedlings S, traveling, etc. Therefore, the seedling planting device 1 according to this embodiment can stably perform the planting work of seedlings S.

[0089] Furthermore, in the seedling planting device 1, when the traveling direction of the vehicle body 2A and crawlers 2C on a horizontal plane is the front-to-rear direction, the attitude maintaining unit 80 maintains the seedling placing unit 10 and the seedling removal unit 30 in a horizontal attitude by adjusting the tilt in the roll direction relative to the vehicle body 2A. In this attitude, the seedling S on the seedling placing unit 10 is maintained vertical at least in the roll direction. For example, by placing the seedling planting device 1 with the horizontal direction relative to the sloping ground G as the front-to-rear direction, the attitudes of the seedling placing unit 10 and the seedling removal unit 30 can be maintained in a good horizontal attitude. Therefore, the seedling planting device 1 allows the seedling removal unit 30 to stably remove the seedling S from the seedling placing unit 10.

[0090] The seedling planting device 1 also includes a carrier 2B serving as a first connecting part. When the traveling direction of the vehicle body 2A, which travels on a horizontal plane using crawlers 2C, is defined as the front-to-rear direction, the carrier 2B is connected to the vehicle body 2A so as to be rotatable around a rotation axis A1 serving as a predetermined first axis in a roll direction, which serves as a first direction. The carrier 2B is also connected to a seedling removal unit 3 having a seedling placement unit 10 and a seedling removal unit 30. In the seedling planting device 1, the attitude maintaining unit 80 includes a first tilt adjusting unit 81. The first tilt adjusting unit 81 rotates the carrier 2B in the roll direction relative to the vehicle body 2A. The first tilt adjusting unit 81 includes a first pivot support unit 81A, a vehicle-side bracket 81B serving as a traveling unit-side bracket, a carrier-side first bracket 81C serving as a first connecting unit-side first bracket, and a first cylinder 81D. The first pivotal support portion 81A pivotally supports rotation of the bed 2B about the rotation axis A1 relative to the vehicle body 2A. The vehicle body side bracket 81B is fixed to the vehicle body 2A at a position that is a distance L1, which is a first predetermined distance, away from the first pivotal support portion 81A. The bed side first bracket 81C is fixed to the bed 2B at a position that is a distance L2, which is a second predetermined distance, away from the first pivotal support portion 81A and at a position that is an angle d1, which is a first predetermined angle, around the rotation axis A1 from the vehicle body side bracket 81B. The first cylinder 81D connects both ends to the vehicle body side bracket 81B and the bed side first bracket 81C, and expands and contracts between the vehicle body side bracket 81B and the bed side first bracket 81C, rotating the bed 2B about the rotation axis A1 relative to the vehicle body 2A. With such a simple configuration, the seedling planting device 1 can maintain the seedling placing unit 10 and the seedling extracting unit 30 in a horizontal position in the roll direction.

[0091] The seedling planting device 1 according to the first embodiment includes a main slider 40, a hole forming unit 50, and a planting unit 60. The hole forming unit 50 is supported by the main slider 40 and forms a hole D in the ground G. The planting unit 60 is supported by the main slider 40 and plants a seedling S in the hole D. The hole forming unit 50 and the planting unit 60 are provided so as to be independently movable relative to the main slider 40.

[0092] This configuration allows for a simplified configuration of the seedling planting device 1. In other words, unlike when the hole forming section and the planting section are supported separately, the seedling planting device 1 is supported by a single support member, the main slider 40. This allows for a simplified configuration of the seedling planting device 1.

[0093] Furthermore, in the seedling planting device 1, the main slider 40 is provided to be movable in the vertical direction. The hole forming unit 50 and the planting unit 60 are movable in the direction of movement of the main slider 40. This allows the seedling planting device 1 to perform planting work stably. Specifically, the seedling planting device 1 can ensure the vertical movement of the hole forming unit 50 and the planting unit 60 while reducing the overall height. For example, if only the hole forming unit and the planting unit move up and down and the main slider does not move, ensuring the required movement distance requires an additional device height. In contrast, in the seedling planting device 1, the main slider 40, which supports the hole forming unit 50 and the planting unit 60 for vertical movement, is itself movable up and down. This allows the seedling planting device 1 to divide the required movement distance into two lifting mechanisms and set it, thereby reducing the overall height of the device. As a result, the seedling planting device 1 can maintain a low center of gravity and ensure device stability.

[0094] Furthermore, the seedling planting device 1 according to the first embodiment plants a seedling S in the ground G on a planting axis P, which is an arbitrary axis. The seedling planting device 1 includes a hole forming unit 50, a planting unit 60, and a posture maintaining unit 80. The hole forming unit 50 forms a hole D in the ground G on the planting axis P. The planting unit 60 moves the seedling S on the planting axis P and plants it in the hole D. The posture maintaining unit 80 maintains the posture of the hole forming unit 50 and the planting unit 60 so that the planting axis P is vertical.

[0095] With this configuration, the seedling planting device 1 can stably perform planting work. Specifically, the seedling planting device 1 can stably form a hole D using the hole forming unit 50 and plant a seedling S into the hole D using the planting unit 60. By providing the position maintaining unit 80, the seedling planting device 1 can maintain the position of the hole forming unit 50 and the planting unit 60 so that the planting axis P is vertical, even if the device tilts due to a slope of the ground G. This allows the hole forming unit 50 and the planting unit 60 to plant the seedling S in a position that follows the vertical direction, regardless of the degree of slope of the ground G when planting the seedling S. Therefore, the seedling planting device 1 according to this embodiment can stably perform planting work of the seedling S.

[0096] Furthermore, in the seedling planting device 1, when the traveling direction of the vehicle body 2A and crawler 2C on a horizontal plane is the front-to-rear direction, the attitude maintaining unit 80 adjusts the tilt in the roll direction relative to the vehicle body 2A to maintain the attitude of the hole forming unit 50 and the planting unit 60 so that the planting axis P is vertical. As a result, the seedling planting device 1 can maintain the verticality of the planting axis P by, for example, placing it with the horizontal direction relative to the sloping ground G as the front-to-rear direction.

[0097] Furthermore, in the seedling planting device 1, when the traveling direction of the vehicle body 2A and crawler 2C on a horizontal plane is the front-to-rear direction, the attitude maintaining unit 80 adjusts the tilt in the pitch direction relative to the vehicle body 2A to maintain the attitude of the hole forming unit 50 and the planting unit 60 so that the planting axis P is vertical. As a result, the seedling planting device 1 can maintain the verticality of the planting axis P by, for example, placing it with the tilt direction relative to sloping ground G as the front-to-rear direction.

[0098] The seedling planting device 1 also includes a carrier 2B as a first connecting part and a slider support part 41 as a second connecting part. When the traveling direction of the vehicle body 2A, which travels on a horizontal plane using crawlers 2C, is defined as the longitudinal direction, the carrier 2B is connected to the vehicle body 2A so as to be rotatable around a rotation axis A1 as a predetermined first axis in a roll direction as a first direction. The slider support part 41 is connected to the first connecting part so as to be rotatable around a rotation axis A3 as a predetermined second axis in a pitch direction as a second direction. The slider support part 41 is also connected to a seedling planting unit 4 having a hole forming part 50 and a planting part 60. In this seedling planting device 1, the attitude maintaining part 80 includes a first tilt adjusting part 81 and a second tilt adjusting part 82.

[0099] The first tilt adjustment unit 81 rotates the bed 2B in the roll direction relative to the vehicle body 2A. The first tilt adjustment unit 81 has a first pivot support unit 81A, a vehicle body side bracket 81B as a running unit side bracket, a bed side first bracket 81C as a first connecting unit side first bracket, and a first cylinder 81D. The first pivot support unit 81A pivots to support rotation of the bed 2B around a rotation axis A1 relative to the vehicle body 2A. The vehicle body side bracket 81B is fixed to the vehicle body 2A at a position spaced a distance L1, which is a first predetermined distance, from the first pivot support unit 81A. The bed side first bracket 81C is fixed to the bed 2B at a position spaced a distance L2, which is a second predetermined distance, from the first pivot support unit 81A and at a first predetermined angle d1, which is a first predetermined angle, around the rotation axis A1 from the vehicle body side bracket 81B. The first cylinder 81D connects both ends to the vehicle body side bracket 81B and the cargo bed side first bracket 81C, and expands and contracts between the vehicle body side bracket 81B and the cargo bed side first bracket 81C, rotating the cargo bed 2B around the rotation axis A1 relative to the vehicle body 2A.

[0100] The second tilt adjustment unit 82 rotates the slider support unit 41 in the pitch direction relative to the loading platform 2B. The second tilt adjustment unit 82 has a second pivotal support unit 82A, a loading platform-side second bracket 82B, a slider support unit-side bracket 82C, and a second cylinder 82D. The second pivotal support unit 82A pivotally supports rotation of the slider support unit 41 around a rotation axis A3 relative to the loading platform 2B. The loading platform-side second bracket 82B is fixed to the loading platform 2B at a distance L3 (a third predetermined distance) from the second pivotal support unit 82A. The slider support unit-side bracket 82C is fixed to the slider support unit 41 at a distance L4 (a fourth predetermined distance) from the second pivotal support unit 82A and at a second predetermined angle d2 (a second predetermined angle) around the rotation axis A3 from the loading platform-side second bracket 82B. The second cylinder 82D connects both ends to the platform-side second bracket 82B and the slider support unit-side bracket 82C, and extends and retracts between the platform-side second bracket 82B and the slider support unit-side bracket 82C, rotating the slider support unit 41 about the rotation axis A3 relative to the platform 2B. This configuration easily realizes a configuration in which the seedling planting device 1 can plant seedlings S in a vertical position regardless of the degree of inclination of the ground G. The seedling planting device 1 can maintain the position of the seedling planting unit 4 so that the planting axis P is vertical, regardless of the direction in which it is placed relative to the slope.

[0101] The seedling planting device 1 also includes a remote control device RC. The remote control device RC remotely controls the seedling removal unit 30, the hole forming unit 50, and the planting unit 60 to perform a series of operations from removing the seedling S to planting it in the ground G. Therefore, the seedling planting device 1 can safely perform the planting work of the seedling S from a remote location.

[0102] Furthermore, the seedling planting device 1 is provided with a main slider 40 that is movable up and down, and the hole forming unit 50 and the planting unit 60 are each movable up and down relative to the main slider 40. With this configuration, the seedling planting device 1 can simplify the configuration of the device and the operation of the device related to planting the seedling S. That is, by simply determining the height position of the main slider 40 relative to the ground G, the seedling planting device 1 can form a hole D of a predetermined depth in a layer Gh of a predetermined hardness in the ground G by lowering each of the hole forming unit 50 and the planting unit 60 by a fixed amount relative to the main slider 40, and can lower the seedling S to an appropriate position relative to the hole D. Therefore, the seedling planting device 1 does not need to provide a lowering amount measuring means such as an encoder in each of the hole forming unit 50 and the planting unit 60 to individually determine the lowering amount of each of the hole forming unit 50 and the planting unit 60 for each planting of a seedling S, thereby simplifying the configuration and the operation of planting the seedling S. Furthermore, the seedling planting device 1 can determine the height position of the main slider 40 relative to a layer Gh of a predetermined hardness in the ground G using the detection unit 70. As a result, the seedling planting device 1 can extremely easily achieve simplification of the device configuration and the operation of planting the seedling S.

[0103] The seedling planting device 1 according to the first embodiment also includes a seedling extraction device 20. The seedling extraction device 20 extracts seedlings S from a container C having an array of multiple cultivation holes H for accommodating the seedlings S. The seedling extraction device 20 includes a seedling placement unit 10 and multiple actuators 21A, 21B, 21C, and 21D. The seedling placement unit 10 places the container C containing the seedlings S. The multiple actuators 21A, 21B, 21C, and 21D are disposed below the seedling placement unit 10 and apply a force to the seedlings S that pushes the seedlings S upward from the cultivation holes H, thereby pushing the seedlings S out of each of the multiple cultivation holes H. The multiple actuators 21A, 21B, 21C, and 21D sequentially push the multiple seedlings S one by one out of the cultivation holes H. Then, the seedling arranging unit 10 moves the container C so that the plurality of cultivation holes H pass above the actuators 21A, 21B, 21C, and 21D in sequence for each row.

[0104] With this configuration, the seedling extraction device 20 can output a smaller force to push out the seedlings S in the container C than when all the seedlings are pushed out at once. Therefore, the seedling extraction device 20 does not need to be durable enough to withstand the large force required to simultaneously push out multiple seedlings, allowing for a simplified structure. Furthermore, because the seedling extraction device 20 can reduce the output per push, it can also reduce the force acting on the container C. As a result, the seedling extraction device 20 can prevent deformation and damage to the container C compared to when multiple seedlings S are simultaneously pushed out. Furthermore, the seedling placement unit 10 moves the container C so that multiple cultivation holes H pass over the actuators 21A, 21B, 21C, and 21D in succession, so the number of actuators 21A, 21B, 21C, and 21D can be reduced compared to when one actuator is provided for each cultivation hole. As a result, the seedling extraction device 20 can be simplified.

[0105] The seedling extraction device 20 includes multiple hydraulic actuators 21A, 21B, 21C, and 21D and multiple sequence valves 22A, 22B, and 22C, the number of which is one less than the number of actuators 21A, 21B, 21C, and 21D. The multiple sequence valves 22A, 22B, and 22C are arranged in series in a flow path that supplies fluid pressure to each of the actuators 21A, 21B, 21C, and 21D. One of the multiple actuators 21A, 21B, 21C, and 21D is connected to a fluid pressure supply flow path upstream of the sequence valve 22A, which is located most upstream in the fluid pressure supply flow path, and the other actuators 21B, 21C, and 21D are connected to fluid pressure supply flow paths downstream of each of the sequence valves 22A, 22B, and 22C. Therefore, the seedling extraction device 20 can extract multiple seedlings S one by one with a simple configuration.

[0106] The seedling planting device 1 uses the seedling extraction device 20 to extract multiple seedlings S one by one, in a row, from the container C. Therefore, when extracting seedlings S with the extraction chuck 32, the seedling planting device 1 leaves the root balls R of seedlings S that are not to be extracted undissolved, thereby enabling successful extraction of only the seedlings S to be extracted. For example, consider a case where a branch of a seedling S that is not to be extracted becomes entangled with another branch of the seedling S that is to be extracted when the seedling S to be extracted is grasped by the extraction chuck 32. In this case, if the root balls R of the seedlings S that are not to be extracted are not dissolved from the root balls R in the cultivation hole H, when the seedling S to be extracted is grasped and lifted, the seedlings S that are not to be extracted will remain in the container C in a state where they are stuck in the cultivation hole H. In this way, the seedling planting device 1 dissolves the root balls R of the seedlings S to be extracted and leaves the root balls R of the seedlings S that are not to be extracted undissolved. This allows the seedling planting device 1 to successfully pick up only the seedlings S to be picked up by the seedling picking section 30.

[0107] The seedling planting device 1 according to the first embodiment includes a seedling arrangement unit 10 and a seedling removal unit 30. The seedling arrangement unit 10 arranges a plurality of seedlings S before planting. The seedling removal unit 30 removes the seedlings S from the seedling arrangement unit 10. The seedling removal unit 30 has a removal chuck 32 and at least one partition plate 33. The removal chuck 32 has a pair of claws 32A and a claw support unit 32B. The pair of claws 32A grip the seedlings S. The claw support unit 32B supports the pair of claws 32A so that the spacing between the pair of claws 32A can be freely changed. The partition plate 33 is positioned outside the claw support unit 32B in the movement direction when the spacing between the pair of claws 32A is changed.

[0108] With this configuration, when the seedling removal unit 30 removes a seedling S, the seedling planting device 1 can position the partition plate 33 between the seedling S to be gripped by the removal chuck 32 and the adjacent seedling S that is not the target of gripping. Therefore, even if the branches of the adjacent seedling S that is not the target of gripping are entangled with the target seedling S, the partition plate 33 can untangle the entanglement, allowing only the target seedling S to be successfully removed. Furthermore, the partition plate 33 is positioned so as to be separated from the spacing change operation of the pair of claws 32A. Therefore, when the partition plate 33 is positioned between the target seedling S and the seedling S that is not the target of gripping, it can maintain its position without moving in accordance with the spacing change operation of the pair of claws 32A. As a result, the seedling planting device 1 can effectively use the partition plate 33 to separate the seedlings S.

[0109] Furthermore, the front edge of the partition plate 33, which faces the seedling S to be removed, is inclined rearward in the facing direction as it extends upward. Therefore, the seedling planting device 1 can reduce resistance when the partition plate 33 is inserted between the seedlings S. This is because the branches of plants such as seedlings branch out from the base of the trunk. In other words, when the partition plate 33 is configured to be inclined rearward in the facing direction as it extends upward, the partition plate 33 can be inserted from below the base of the branches, and the inclined surface of the front edge can be used to push the branches upward while inserting. Therefore, the partition plate 33 can be easily inserted with little resistance to insertion.

[0110] <Embodiment 2> Next, a second embodiment of the seedling planting device of the present invention will be described with reference to the drawings.

[0111] The seedling planting device 201 of the second embodiment plants a seedling S in the ground G on a planting axis P. The planting axis P is a virtual axis that is arbitrarily set on the seedling planting device 201 as shown in FIGS. 26 and 27. The seedling S to be planted by the seedling planting device 201 moves along this planting axis P. The ground G on which the seedling S is planted is a forestry site such as a mountain forest, and is primarily a slope. A soft layer Gs such as leaf mold may be formed on the surface of the ground G (see FIG. 26, etc.). In the ground G, a layer suitable for planting the seedling S is a layer Gh having a predetermined hardness below the soft layer Gs. This predetermined hardness is preferably, for example, approximately the same as the hardness of the root ball R of the seedling S, but is not particularly limited thereto.

[0112] As shown in Figures 26 to 28, the seedling planting device 201 includes a traveling unit 202 and a seedling planting unit 204. The traveling unit 202 includes a vehicle body 202A, a rotary support unit 202B, and a crawler-type endless track (hereinafter simply referred to as a crawler) 2C. The vehicle body 202A is box-shaped. The vehicle body 202A is equipped with functional units (not shown) such as an engine, a battery, a fluid pressure unit, and a control unit. Each unit of the seedling planting device 201, which will be described later, includes a fluid pressure actuator, an electric actuator, etc., and is driven and controlled by these functional units. Each unit of the seedling planting device 201 can be operated by a remote control device RC capable of wireless communication.

[0113] The rotation support part 202B extends rearward from the rear of the vehicle body 202A. The rotation support part 202B is rotatably connected to the vehicle body 202A around a rotation axis A201. The rotation axis A201 is set as an axis extending parallel to the left-right direction at the rear end of the vehicle body 202A. The rotation support part 202B also rotatably connects the seedling planting unit 204 connected to the rear end around the rotation axis A202. The rotation axis A202 is set as an axis parallel to the front-rear direction at the rear end of the rotation support part 202B. When the vehicle body 202A tilts due to the inclination of the ground G, the rotation support part 202B rotates the seedling planting unit 204 around the rotation axes A201 and A202, thereby maintaining the posture of the seedling planting unit 204. The function of the rotation support part 202B to rotate around the rotation axis A201 relative to the vehicle body 202A, and the function of the rotation support part 202B to rotate the seedling planting unit 204 around the rotation axis A202 function as an attitude maintaining part 280 described later.

[0114] A pair of crawlers 202C are provided on the left and right sides of the vehicle body 202A. The crawlers 202C are wound around a drive pulley 202D and a driven pulley 202E, which are rotatably supported on the vehicle body 202A. As shown in Fig. 26, the crawlers 202C are wound around the drive pulley 202D and the driven pulley 202E in the shape of an oval ring that is long in the front-rear direction in a side view.

[0115] The seedling planting unit 204 is disposed behind the traveling unit 202. The seedling planting unit 204 is connected at its front end to the rotation support part 202B of the traveling unit 202. A planting axis P is set on the seedling planting unit 204. The planting axis P is usually set to extend in the up-down direction (vertical direction). The seedling planting unit 204 is rotatable in the front-back and left-right directions by the rotation support part 202B. For example, when the traveling unit 202 tilts due to the inclination of the ground G, the seedling planting unit 204 can rotate around the rotation axes A201 and A202 to tilt in the opposite direction to the inclination of the traveling unit 202 and maintain its posture. The seedling planting unit 204 maintains its posture so that the planting axis P is vertical, regardless of the degree of inclination of the ground G.

[0116] As shown in Figures 26 to 28, the seedling planting unit 204 has a main slider 240, a seedling placement section 210, a hole forming section 250, a planting section 260, and a detection section 270. The main slider 240 is provided so as to be movable up and down along the planting axis P. Specifically, the main slider 240 is movably supported by a slider support section 241. The slider support section 241 extends up and down and moves the main slider 240 along its extension direction. The slider support section 241 is a connection section with the rotation support section 202B of the traveling unit 202 in the seedling planting unit 204. The slider support section 241 is rotatable around two rotation axes A201 and A202 relative to the rotation support section 202B. Therefore, it can be said that the main slider 240 is rotatably supported by the rotation support portion 202B via the slider support portion 241.

[0117] In the seedling planting unit 204, the hole forming section 250, the planting section 260, and the detection section 270 are each supported by the main slider 240. Therefore, the hole forming section 250, the planting section 260, and the detection section 270 move and rotate in accordance with the movement of the main slider 240 in the planting axis P direction and the rotation about the rotation axes A201 and A202. Furthermore, the seedling placing section 210 in the seedling planting unit 204 is fixedly supported by the slider support section 241. Therefore, the seedling placing section 210 rotates in accordance with the rotation of the slider support section 241 about the rotation axes A201 and A202, but does not follow the up-and-down movement of the main slider 240.

[0118] The seedling arranging section 210 arranges seedlings S before planting. As shown in Figures 26 to 28, the seedling arranging section 210 has a plurality of storage tubes 211 and a conveyor 212. The storage tubes 211 are cylindrical and open at the top. A plurality of storage tubes 211 are provided. The plurality of storage tubes 211 are arranged side by side on the conveyor 212. The seedlings S are arranged with their root balls R accommodated in the storage tubes 211. One seedling S is accommodated in each storage tube 211. In this way, a plurality of seedlings S are arranged in the seedling arranging section 210.

[0119] In the seedling placement section 210, a plurality of storage tubes 211 are moved in a circular motion by a conveyor 212. As shown in FIG. 27, a take-out position 212A is set on the conveyor 212. The plurality of storage tubes 211 are sequentially moved to the take-out position 212A by the indexing operation of the conveyor 212. This take-out position 212A is a position where a seedling S is taken out by a planting chuck 261 (described later) in the planting section 260. When taking out a seedling S from the seedling placement section 210, the planting chuck 261 takes out the seedling S from the storage tube 211 located at the take-out position 212A. The seedling placement section 210 is movable left and right. After the seedling S is taken out from the take-out position 212A by the planting chuck 261, the seedling placement section 210 retracts the take-out position 212A to the left. This allows the planting chuck 261 to move up and down without coming into contact with the seedling placement section 210.

[0120] The hole forming unit 250 forms a hole D (see Figure 38) in the ground G for planting a seedling S. As shown in Figures 27 and 28, the hole forming unit 250 is disposed to the rear right of the main slider 240. The hole forming unit 250 is movable up and down along the planting axis P from an upper end position indicated by a solid line in Figure 29 to a lower end position indicated by a two-dot chain line. The hole forming unit 250 is supported by a guide rail 250A. The guide rail 250A supports the hole forming unit 250 so that it can move freely. The guide rail 250A is fixedly disposed relative to the main slider 240. By moving up and down relative to this guide rail 250A, the hole forming unit 250 also moves up and down relative to the main slider 240.

[0121] The hole forming unit 250 is movable between a position on the planting axis P shown by the two-dot chain line in Figure 30 and a position retracted from the planting axis P shown by the solid line. This movement is due to rotation around the rotation axis A203. The rotation axis A203 is set as an axis parallel to the planting axis P. Therefore, this movement is movement in a direction intersecting the planting axis P. The hole forming unit 250 moves onto the planting axis P and descends on this planting axis P to form a hole D in the ground G on the planting axis P. The upper end position and the position retracted from the planting axis P are the initial positions of the hole forming unit 250.

[0122] As shown in Figures 29 and 30, the hole forming unit 250 includes a drill 251, a drill shank 252, a drill support 253, and a drill moving mechanism 254. The drill 251 includes a conical portion 251A and an expanded diameter portion 251B. The conical portion 251A has a conical spiral shape and expands in diameter as it extends upward. The expanded diameter portion 251B is connected to the upper end of the conical portion 251A. The expanded diameter portion 251B has a spiral shape with an outer diameter that expands in a stepped manner from the outer diameter at the upper end of the conical portion 251A. The expanded diameter portion 251B sweeps away soil from the upper edge of the depression formed by the conical portion 251A and further forms a countersunk depression at the upper end of the depression (see Figure 38, etc.). The drill shank 252 is connected to the upper end of the drill 251 and transmits power to the drill 251 for rotating the drill 251. The drill support 253 supports the drill shank 252 rotatably.

[0123] The drill moving mechanism 254 moves the drill 251. Specifically, the drill moving mechanism 254 can move the drill 251 in two directions: along the planting axis P and in a direction intersecting the planting axis P. As shown in FIGS. 29 and 30, the drill moving mechanism 254 has a first member 254A and a second member 254B. The first member 254A is supported by the guide rail 250A so as to be movable up and down. In other words, the movement of the drill 251 along the planting axis P by the drill moving mechanism 254 is the movement in the up and down direction by the guide rail 250A. Note that at the upper end position of the hole forming part 250 shown in FIG. 29, the upper end 254C of the first member 254A corresponds to the upper end of the hole forming part 250.

[0124] The second member 254B is supported by the first member 254A so as to be movable in a direction intersecting the planting axis P. The second member 254B also supports the drill support unit 253. That is, the drill moving mechanism unit 254 moves the drill 251 in a direction intersecting the planting axis P between a position on the planting axis P and a position retracted from the planting axis P. The second member 254B moves in a direction intersecting the planting axis P by rotating around the rotation axis A203 set between the second member 254B and the first member 254A. The drill 251 rotates between the position on the planting axis P and the retracted position by the relative rotation of the second member 254B around the rotation axis A203 with respect to the first member 254A.

[0125] The planting unit 260 plants seedlings S in the holes D formed by the hole forming unit 250. As shown in Figures 27 and 28, the planting unit 260 is disposed to the left rear of the main slider 240. The planting unit 260 is movable up and down along the planting axis P from the upper end position indicated by the solid line in Figure 31 to the lower end position indicated by the two-dot chain line. The planting unit 260 is supported by a guide rail 260A. The guide rail 260A supports the planting unit 260 so that it can move freely. The guide rail 260A is provided with the same specifications as the guide rail 250A in the hole forming unit 250. In other words, the guide rails 250A and 260A have the same length, cross-sectional shape, etc. The guide rail 260A is fixedly disposed relative to the main slider 240. The planting section 260 moves up and down relative to the guide rail 260A, and thereby also moves up and down relative to the main slider 240. The guide rails 250A and 260A, which have common specifications, have directional cross-sectional shapes and are respectively arranged symmetrically with respect to the main slider 240.

[0126] The planting unit 260 is movable between a position on the planting axis P shown by the solid line in FIG. 32 and a position on the planting axis P shown by the two-dot chain line, where the planting unit 260 is retracted. This movement is due to rotation around the rotation axis A204. The rotation axis A204 is set as an axis parallel to the planting axis P. Therefore, this movement is movement in a direction intersecting the planting axis P. The planting unit 260 takes the seedling S from the seedling placement unit 210, moves it onto the planting axis P, and descends on this planting axis P, thereby planting the seedling S into the hole D by the hole forming unit 250. The upper end position and the position on the planting axis P of the planting unit 260 are initial positions.

[0127] As shown in Figures 31 and 32, the planting unit 260 has a planting chuck 261 and a chuck movement mechanism 263. The planting chuck 261 has a pair of left and right claws 261A whose distance from each other can be changed, and a claw support 261B that supports the pair of claws 261A so that the distance between them can be changed. The planting chuck 261 grips the seedling S with the pair of claws 261A. The chucked seedling S is lowered along the planting axis P shown in Figure 32 and other figures to be planted. As shown in Figure 31, the planting chuck 261 also has a pressing member 261C. The pressing member 261C is plate-shaped with a U-shaped notch in a plan view and is positioned below the pair of claws 261A. The pressing member 261C is lowered after inserting the seedling S into the hole D to compact the root ball R and the soil around the root ball R. The U-shaped cutout in the pressing member 261C is smaller than the diameter of the root ball R of the seedling S and is formed to a size that allows the trunk of the seedling S to pass through. The size of the cutout in the pressing member may be, for example, smaller than the inner diameter of the hole D. In this case, too, the seedling can be fixed in place by compacting at least the soil around the root ball.

[0128] The chuck moving mechanism 263 moves the planting chuck 261. Specifically, the chuck moving mechanism 263 can move the planting chuck 261 in two directions: along the planting axis P and in a direction intersecting the planting axis P. As shown in Figures 31 and 32, the chuck moving mechanism 263 has a first member 263A and a second member 263B. The first member 263A is supported by the guide rail 260A so as to be movable up and down. In other words, the movement of the planting chuck 261 along the planting axis P by the chuck moving mechanism 263 is the movement in the up and down direction by the guide rail 260A. Note that at the upper end position of the planting part 260 shown in Figure 31, the upper end 263C of the first member 263A corresponds to the upper end of the planting part 260. When the planting part 260 is in the upper end position, the upper end 263C of the first member 263A is set at a position substantially equivalent to the upper end 254C of the first member 254A when the hole forming part 250 is in the upper end position.

[0129] The second member 263B is supported by the first member 263A so as to be movable in a direction intersecting the planting axis P. The second member 263B also supports the claw support portion 261B of the planting chuck 261. That is, the chuck movement mechanism 263 moves the planting chuck 261 in a direction intersecting the planting axis P between a position on the planting axis P and a position retracted from the planting axis P. The second member 263B moves in a direction intersecting the planting axis P by rotating around the rotation axis A204 set between the second member 263B and the first member 263A. The planting chuck 261 rotates between a position retracted from the planting axis P and a position on the planting axis P by the relative rotation of the second member 263B with respect to the first member 263A about the rotation axis A204.

[0130] The planting chuck 261 moves up and down due to the relative movement of the first member 263A of the chuck movement mechanism 263 with the guide rail 260A, and pivots between a position on the planting axis P and a retracted position due to the relative rotation of the second member 263B about the rotation axis A204 with respect to the first member 263A. The planting chuck 261 takes out the seedling S from the take-out position 212A by pivoting from its position on the planting axis P. The planting chuck 261 pivots onto the planting axis P while gripping the taken-out seedling S, and plants the taken-out seedling S into the hole D at this position on the planting axis P.

[0131] As shown in Figures 27 and 28, the guide rails 250A in the hole forming unit 250 and the guide rails 260A in the planting unit 260 are arranged approximately symmetrically on the left and right behind the main slider 240. As described above, the guide rails 250A, 260A have the same specifications in terms of length, cross-sectional shape, etc. In the seedling planting device 201, the guide rails 250A, 260A are set to be approximately equal in terms of upper end positions, front-to-rear positions, etc. The hole forming unit 250 and the planting unit 260, which are movably supported on these guide rails 250A, 260A, respectively, move up and down and turn along symmetrical trajectories.

[0132] The detection unit 270 detects a layer Gh of a predetermined hardness on the ground G. As described above, the layer Gh of a predetermined hardness is a layer on the ground G that has a hardness suitable for planting a seedling S. On the ground G, it is difficult to stably fix a seedling S in a soft layer Gs such as leaf mold on the surface. Therefore, the seedling planting device 201 uses the detection unit 270 to detect a layer Gh of a hardness suitable for planting a seedling S, and plants the seedling S in this layer Gh. The hardness suitable for planting a seedling S is, for example, a hardness equivalent to that of the root ball R of the seedling S.

[0133] The detection unit 270 has a ground contact portion 271 and a load cell (not shown). As shown in FIGS. 29 and 31 , the ground contact portion 271 comes into contact with the ground G. The detection unit 270 detects a layer Gh of a predetermined hardness on the ground G based on the contact of the ground contact portion 271 with the ground G. As shown in FIG. 31 , the ground contact portion 271 is provided on the lower part of the main slider 240. The ground contact portion 271 extends downward in a rod shape from the lower end of the main slider 240. The ground contact portion 271 comes into contact with the ground G as the main slider 240 descends. The main slider 240 continues to descend until the lower end of the ground contact portion 271 reaches a layer Gh of a predetermined hardness on the ground G.

[0134] The load cell measures the magnitude of the load when the ground contact portion 271 is pressed against the ground G. As a result, when the detection unit 270 measures the magnitude of the load corresponding to the magnitude when the ground contact portion 271 is pressed against a layer Gh of a predetermined hardness, it can detect the layer at that depth as a layer of the predetermined hardness.

[0135] The detection of the layer of a predetermined hardness is not limited to the use of the load cell. For example, the detection of the layer of a predetermined hardness may be performed using a configuration including a spring that contracts in response to the magnitude of the load when the contact portion is lowered and pressed against the ground, a detection object such as a magnetic member or a dog plate that changes position as the spring contracts, and a detection unit that detects the change in position of the detection object and detects when the spring has contracted to a predetermined length, such as a non-contact or contact switch. Alternatively, the detection may be performed by calculating the magnitude of the thrust when the contact portion is lowered and pressed against the ground from the load of the thrust generating means, and detecting the layer of a predetermined hardness based on this. In this case, the thrust generating means may be, for example, a fluid pressure actuator or an electric actuator.

[0136] The seedling planting device 201 is equipped with a posture maintaining unit 280. The posture maintaining unit 280 maintains the posture of the seedling planting unit 204 in a predetermined posture. The predetermined posture is a posture in which the planting axis P is vertical. This allows the seedling planting device 201 to stabilize the planting of the seedling S by the seedling planting unit 204.

[0137] In this embodiment, the posture maintaining section 280 maintains the posture of the seedling planting unit 204 in a posture in which the seedling planting device 201 is on a horizontal plane (hereinafter also referred to as the horizontal posture) as shown in Figures 26 and 27. In this horizontal posture, the seedling S on the seedling placing section 210 is placed in a posture extending vertically upward from the root ball R. In addition, in the horizontal posture, the planting axis P of the seedling planting unit 204 is vertical.

[0138] As shown in Figures 33 and 34, the attitude maintaining section 280 has a first tilt adjusting section 281 and a second tilt adjusting section 282. The seedling planting device 201 shown in Figures 33 and 34 has been simplified by omitting some of the components other than the essential parts. The tilt of the seedling planting unit 204 in the front-to-back direction (pitch direction) is adjusted by the first tilt adjusting section 281. The tilt of the seedling planting unit 204 in the left-to-right direction (roll direction) is adjusted by the second tilt adjusting section 282. The attitude maintaining section 280 has detection means (not shown) that can detect tilt, such as an inclination sensor, acceleration sensor, or angular velocity sensor, and maintains the attitude based on the detection results of this detection means.

[0139] The first tilt adjustment unit 281 rotates the rotation support unit 202B in the pitch direction relative to the vehicle body 202A. That is, the first tilt adjustment unit 281 adjusts the tilt of the rotation support unit 202B in the pitch direction relative to the vehicle body 202A. The second tilt adjustment unit 282 rotates the slider support unit 241 in the roll direction relative to the rotation support unit 202B. That is, the second tilt adjustment unit 282 adjusts the tilt of the slider support unit 241 in the roll direction relative to the rotation support unit 202B.

[0140] 33, the first tilt adjustment section 281 has a first pivotal support section 281A, a vehicle body side bracket 281B, a rotation support section side first bracket 281C, and a first cylinder 281D. The first pivotal support section 281A supports rotation of the rotation support section 202B relative to the vehicle body 202A about a rotation axis A201. The first pivotal support section 281A connects a vehicle body side pivotal support member 281A1 and a rotation support section side first pivotal support member 281A2 so as to be rotatable relative to each other about the rotation axis A201. The vehicle body side pivotal support member 281A1 protrudes rearward from the rear end of the vehicle body 202A.

[0141] 33 and 34, the rotation support part first pivotal support member 281A2 is provided in front of the mounting base 291 of the rotation support part 202B. In detail, the rotation support part 202B has a mounting base 291 extending in the left-right direction, and a pair of arms 292, 293 extending forward from both left and right ends of the mounting base 291. The rotation support part first pivotal support member 281A2 is connected to the front ends of the arms 292, 293. The rotation support part first pivotal support member 281A2 is disposed between the pair of left and right arms 292, 293.

[0142] The vehicle body side bracket 281B is fixed to the vehicle body 202A at a position that is a predetermined distance L201 away from the first pivotal support portion 281A. The vehicle body side bracket 281B pivotally supports one end of the first cylinder 281D so that it can rotate freely around a rotation axis A205. This rotation axis A205 is an axis that is parallel to the rotation axis A201. In this embodiment, the rotation axis A205 is provided at a position that is away from the first pivotal support portion 281A in the up-down direction.

[0143] The rotation support unit-side first bracket 281C is fixed to the rotation support unit 202B at a position that is a predetermined distance L202 away from the first pivot support unit 281A. The fixed position of this rotation support unit-side first bracket 281C with respect to the rotation support unit 202B is a position that is a predetermined angle d202 away from the vehicle body-side bracket 281B around the rotation axis A201. The rotation support unit-side first bracket 281C pivotally supports the other end of the first cylinder 281D so that it can rotate freely around the rotation axis A206. Like the rotation axis A205, this rotation axis A206 is an axis that is parallel to the rotation axis A201. In this embodiment, the rotation axis A206 is provided at a position that is away from the first pivot support unit 281A in the front-rear direction.

[0144] The predetermined distance L201 between the first pivot support 281A and the vehicle body side bracket 281B is the distance between the rotation axis A201 and the rotation axis A205. The predetermined distance L202 between the first pivot support 281A and the rotation support unit side first bracket 281C is the distance between the rotation axis A201 and the rotation axis A206. The predetermined angle d201 around the rotation axis A201 between the rotation support unit side first bracket 281C and the vehicle body side bracket 281B is the angle between the rotation axis A205 and the rotation axis A206. The predetermined angle d201 around the rotation axis A201 between the rotation support unit side first bracket 281C and the vehicle body side bracket 281B is the angle in the neutral state. The neutral state of the seedling planting device 201 is a state in which the seedling planting device 201 is on a horizontal plane, as in the first embodiment. In this state, the various parts of the seedling planting device 201 are in the following states. That is, the crawler 202C of the traveling unit 202 is in contact with the ground G horizontally, and the planting axis P of the seedling planting unit 204 is vertical. The angle between the first bracket 281C on the rotation support side and the bracket 281B on the vehicle body side changes due to the extension and contraction of the first cylinder 281D. In the seedling planting device 201, the range of this angle change is set to approximately ±40°.

[0145] As shown in Fig. 33, the first cylinder 281D has both ends connected to the vehicle body side bracket 281B and the rotation support unit side first bracket 281C. The first cylinder 281D expands and contracts between the vehicle body side bracket 281B and the rotation support unit side first bracket 281C. This causes the first cylinder 281D to rotate the rotation support unit 202B around the rotation axis A201 relative to the vehicle body 202A. Specifically, the first cylinder 281D is rotatably supported at its bottom side end by the vehicle body side bracket 281B, and rotatably supported at its head side end by the rotation support unit side first bracket 281C. The first cylinder 281D changes the angle around the rotation axis A201 between the vehicle body side bracket 281B and the rotation support unit side first bracket 281C (the angle between the rotation axis A205 and the rotation axis A206) ​​within a range of ±40° by extending or retracting from the length in the neutral state. That is, the first tilt adjustment unit 281 can adjust the tilt of the rotation support unit 202B relative to the vehicle body 202A in the pitch direction within a range of ±40° by extending or retracting the first cylinder 281D.

[0146] 33 and 34, the second tilt adjustment section 282 has a second pivotal support section 282A, a rotation support section-side second bracket 282B, a slider support section-side bracket 282C, and a second cylinder 282D. The second pivotal support section 282A pivotally supports rotation of the slider support section 241 about a rotation axis A202 relative to the rotation support section 202B. The second pivotal support section 282A connects a rotation support section-side second pivotal support member 282A1 to a lower end of the slider support section 241 so as to be rotatable relative to the lower end of the slider support section 241 about the rotation axis A202. The rotation support section-side second pivotal support member 282A1 protrudes rearward from the mounting base 291 and is connected to the lower end of the slider support section 241.

[0147] The rotation support portion side second bracket 282B is fixed to the rotation support portion 202B at a position a predetermined distance L203 away from the second pivot support portion 282A. The rotation support portion side second bracket 282B pivotally supports one end of the second cylinder 282D so that the second cylinder 282D is rotatable about a rotation axis A207. This rotation axis A207 is an axis parallel to the rotation axis A202.

[0148] The slider support unit side bracket 282C is fixed to the slider support unit 241 at a position that is a predetermined distance L204 away from the second pivot support unit 282A. The fixed position of the slider support unit side bracket 282C relative to the slider support unit 241 is a position that is a predetermined angle d202 away from the rotation support unit side second bracket 282B around the rotation axis A202. In this embodiment, the slider support unit side bracket 282C pivotally supports the other end of the second cylinder 282D so that it can rotate freely around the rotation axis A208. Similar to the rotation axis A207, this rotation axis A208 is an axis that is parallel to the rotation axis A202.

[0149] The predetermined distance L203 between the second pivot support portion 282A and the rotation support unit side second bracket 282B is the distance between the rotation axis A202 and the rotation axis A207. The predetermined distance L204 between the second pivot support portion 282A and the slider support unit side bracket 282C is the distance between the rotation axis A202 and the rotation axis A208. The predetermined angle d202 around the rotation axis A202 between the slider support unit side bracket 282C and the rotation support unit side second bracket 282B is the angle between the rotation axis A207 and the rotation axis A208. The predetermined angle d202 around the rotation axis A202 between the slider support unit side bracket 282C and the rotation support unit side second bracket 282B is the angle in a neutral state. The angle between the slider support unit side bracket 282C and the rotation support unit side second bracket 282B changes due to the extension and contraction of the second cylinder 282D. In the seedling planting device 201, the range of this angle change is set to about ±40°.

[0150] 33 and 34, the second cylinder 282D has both ends connected to the rotation support unit side second bracket 282B and the slider support unit side bracket 282C. The second cylinder 282D expands and contracts between the rotation support unit side second bracket 282B and the slider support unit side bracket 282C. This causes the second cylinder 282D to rotate the slider support unit 241 around the rotation axis A202 relative to the rotation support unit 202B. Specifically, the second cylinder 282D is rotatably supported at its bottom side end by the rotation support unit side second bracket 282B, and rotatably supported at its head side end by the slider support unit side bracket 282C. The second cylinder 282D changes the angle around the rotation axis A202 between the rotation support unit side second bracket 282B and the slider support unit side bracket 282C (the angle between the rotation axis A207 and the rotation axis A208) within a range of ±40° by extending or retracting from the length in the neutral state. That is, the second tilt adjustment unit 282 can adjust the tilt of the slider support unit 241 relative to the rotation support unit 202B within a range of ±40° in the roll direction by extending or retracting the second cylinder 282D.

[0151] The seedling planting unit 204 maintains the verticality of the planting axis P by adjusting the tilt in the pitch direction by the first tilt adjustment unit 281 and the tilt in the roll direction by the second tilt adjustment unit 282. The seedlings S planted by the seedling planting unit 204, whose posture is maintained in this manner, are in a vertical posture regardless of the degree of inclination of the ground G. In this manner, the posture maintaining unit 280 maintains the posture of the seedling planting unit 204 so that the planting axis P remains vertical. The posture maintaining unit 280 maintains the posture of the seedling planting unit 204 so that not only the planting axis P is vertical, but also the movement directions of the main slider 240, hole forming unit 250, and planting unit 260 are vertical.

[0152] Next, the operation of the seedling planting device 201 configured as described above will be described. When using the seedling planting device 201 to plant seedlings S, a user of the seedling planting device 201 first places the seedlings S in the seedling placement unit 210. The seedling planting device 201 can place one seedling S in each of the multiple storage tubes 211 in the seedling placement unit 210. The seedling placement unit 210 moves the multiple storage tubes 211 in a circular motion using the conveyor 212. The conveyor 212 moves each storage tube 211 sequentially to the removal position 212A using an indexing operation. The seedlings S in the storage tubes 211 placed at the removal position 212A wait to be removed by the planting chuck 261 in the planting unit 260.

[0153] Next, the user of the seedling planting device 201 moves the seedling planting device 201 to a planting location for the seedling S. The seedling planting device 201 travels using a pair of left and right crawlers 202C, making it highly mobile in adverse terrain such as mountain forests. The seedling planting device 201 can be moved by operating the remote control device RC. The seedling planting device 201 does not require a passenger space, making it easy to achieve a compact size. For example, the seedling planting device according to the present invention can easily be made small enough to fit in the bed of a light vehicle-standard truck. The seedling planting device 201 rotates the seedling planting unit 204 around two rotation axes A201 and A202 and can tilt in the front-rear and left-right directions. This allows the seedling planting device 201 to travel while maintaining the orientation of the seedling planting unit 204. This allows the seedling planting device 201 to travel stably even on sloping ground.

[0154] Once the seedling planting device 201 has been moved to the planting location of the seedling S, the user of the seedling planting device 201 begins planting the seedling S using the seedling planting device 201. The seedling planting device 201 can automatically perform a series of operations from removing the seedling S from the seedling placement section 210 to planting it in the ground G. Immediately before planting of the seedling S begins, the seedling planting unit 204 is tilted about the rotation axes A201 and A202 and is in a posture-maintaining state. Specifically, the seedling planting unit 204 maintains its posture so that the planting axis P is vertical.

[0155] When planting of the seedling S begins, the planting unit 260 uses the planting chuck 261 to remove the seedling S from the seedling placement unit 210. Specifically, as shown in FIG. 35, the planting chuck 261 moves from its initial position on the planting axis P (the position shown in FIG. 27) to a position where it is retracted on the planting axis P. At this time, the planting chuck 261 moves by rotating around the rotation axis A204. Then, the planting chuck 261 removes the seedling S from the storage tube 211 located at the removal position 212A. After the planting chuck 261 moves, the hole forming unit 250 rotates the drill 251 from the retracted position to a position on the planting axis P, as shown in FIG. 35.

[0156] The planting section 260 serving as the seedling removal section may have a partition plate similar to that of the first embodiment. In this embodiment, the seedlings S are moved to the removal position 212A by the conveyor 212. Therefore, the seedlings S that are not to be removed and adjacent to the seedlings S to be removed are only located on one side upstream of the conveyor 212. Therefore, when a partition plate is provided in the seedling planting device 201 of the second embodiment, the partition plate only needs to be located on one side corresponding to the upstream side of the conveyor 212.

[0157] Next, the seedling planting unit 204 raises the main slider 240. As the main slider 240 rises, the hole forming section 250 and the planting section 260 also rise. As the planting section 260 rises in conjunction with the rise of the main slider 240, it can remove the seedling S held by the planting chuck 261 upward from the storage tube 211. Thereafter, the seedling placing section 210 is moved leftward, and the conveyor 212 is retracted from directly below the seedling S held by the planting chuck 261. Note that the amount of lift of the main slider 240 at this time is sufficient so that the upper end of the storage tube 211, which moves as the conveyor 212 retracts, does not come into contact with the root ball R of the seedling S, which has risen together with the planting chuck 261.

[0158] The seedling S taken out from the seedling placing section 210 is planted in a hole D formed by the hole forming section 250. Before the hole forming section 250 forms the hole D, the seedling planting unit 204 detects a layer Gh of a predetermined hardness on the ground G using the detection section 270. Specifically, as shown in FIG. 36 , the seedling planting unit 204 lowers the main slider 240 to press the ground contact section 271 of the detection section 270 against the ground G. The lowering of the main slider 240 causes the ground contact section 271 to penetrate a soft layer Gs on the surface of the ground G and press until it reaches the layer Gh of the predetermined hardness. The seedling planting unit 204 stops the lowering of the main slider 240 when the magnitude of the load measured based on a load cell (not shown) in the detection section 270 reaches a magnitude indicated by the predetermined hardness.

[0159] When the detection unit 270 detects a layer Gh of a predetermined hardness, the hole forming unit 250 and the planting unit 260 descend as the main slider 240 descends. At this time, the seedling placing unit 210 retreats to the left as described above. Therefore, the planting unit 260 can descend together with the main slider 240 to a height below the height position of the conveyor 212 without moving upward relative to the main slider 240 or turning to return to the planting axis P to avoid contact between the planting chuck 261 and the conveyor 212.

[0160] The seedling planting device 201 restricts the height position of the ascending end of the main slider 240 by providing the seedling placement unit 210 with the ability to move laterally. For example, consider a case where the seedling placement unit 210 is immovable laterally. In this case, to avoid contact between the planting chuck 261 and the conveyor 212, the main slider 240 must be raised or rotated back onto the planting axis P by an amount that takes into account the amount of descent when the detection unit 270 detects the layer Gh of a predetermined hardness. In such cases, the overall height of the device increases and unnecessary labor costs increase. In contrast, the seedling planting device 201 allows the amount of elevation of the main slider 240 when removing a seedling S to be set to the minimum required amount, regardless of the amount of descent of the main slider 240 when the detection unit 270 detects the layer Gh of a predetermined hardness.

[0161] Furthermore, if the seedling placing unit 210 cannot move left and right, one possible way to avoid contact between the planting chuck 261 and the conveyor 212 is to rotate the planting unit 260 on the planting axis P when the detection unit 270 detects the layer Gh of a predetermined hardness. However, in this case, unnecessary labor is required, such as retracting the planting unit 260 from the planting axis P again in order for the hole forming unit 250 to form the hole D. By providing the seedling placing unit 210 with the ability to move left and right, the seedling planting device 201 can reduce the height of the entire device and prevent an increase in unnecessary labor required for planting seedlings.

[0162] Thereafter, the seedling planting unit 204 forms a hole D using the hole forming unit 250. The hole forming unit 250 forms a hole D in the ground G on the planting axis P. As shown in FIG. 37, the hole forming unit 250 descends on the planting axis P to form the hole D. At this time, the planting axis P is kept vertical because the seedling planting unit 204 is held in position. Therefore, the formed hole D is formed along the vertical direction regardless of the degree of inclination of the ground G.

[0163] The amount of descent of the hole forming unit 250 is based on the depth of a layer Gh of a predetermined hardness in the ground G. The seedling planting unit 204 lowers the hole forming unit 250 by a predetermined fixed amount of descent while the ground contact portion 271 is in contact with the ground G. This allows the seedling planting unit 204 to form holes D with the same depth in the layer Gh of a predetermined hardness, even in different planting locations, without using a means for measuring the amount of descent, such as an encoder. Furthermore, when the hole forming unit 250 forms the hole D, the ground contact portion 271 remains in contact with the ground G. This allows the hole forming unit 250 to form the hole D in a stable state. After forming the hole D, the hole forming unit 250 then rises, rotates, and returns to its initial position. After the hole forming unit 250 returns to its initial position, the planting unit 260 rotates the planting chuck 261 to a position on the planting axis P.

[0164] The hole forming unit 250 forms the hole D using a drill 251 having a conical portion 251A and an enlarged diameter portion 251B. As shown in Fig. 38, the drill 251 forms a conical depression that can adequately accommodate the root ball R of the seedling S, and also forms the hole D by removing the topsoil around the upper edge of the conical depression. In this way, the hole forming unit 250 can form the hole D that is suitable for planting the seedling S.

[0165] After the hole D is formed by the hole forming section 250, the planting section 260 plants the seedling S in the hole D. Even when the planting section 260 plants the seedling S in the hole D, the seedling planting unit 204 maintains a state in which the ground contact section 271 is in contact with the ground G, and the planting axis P maintains a position along the vertical direction. Therefore, the planting section 260 can plant the seedling S in the hole D in a stable state.

[0166] As shown in FIG. 38 , the planting unit 260 lowers the seedling S held by the planting chuck 261 into the hole D. At this time, the amount of descent of the planting unit 260 is determined based on the depth of a layer Gh of a predetermined hardness in the ground G, similar to the amount of descent of the hole forming unit 250. Therefore, by lowering the planting unit 260 by a preset fixed amount of descent, the seedling planting unit 204 can lower the seedling S to a height position approximately equal to the hole D, even in different planting locations, without using a means for measuring the amount of descent, such as an encoder. The planting unit 260 then releases its grip on the seedling S. This places the seedling S in the hole D. At this time, the planting axis P is maintained vertical by the action of the rotation support unit 202B, so the seedling S is placed in the hole D in a good posture.

[0167] Next, as shown in Figure 39, the planting unit 260 lowers the pressing member 261C to press and compact the root ball R and the surrounding soil with its bottom surface. Finally, as shown in Figure 40, the planting chuck 261 is raised and returned to its initial position, and the main slider 240 is raised and returned to its initial position. This completes the planting of the seedling S.

[0168] As described above, the seedling planting device 201 according to the second embodiment includes the detection unit 270. The detection unit 270 has a ground contact portion 271. The ground contact portion 271 is provided so as to be movable in the vertical direction and comes into contact with the ground G. The detection unit 270 detects a layer Gh of a predetermined hardness in the ground G based on the contact of the ground contact portion 271 with the ground G. The seedling planting device 201 according to the second embodiment also achieves the same effect as the first embodiment, and can properly determine a layer Gh of a hardness in the ground G that is suitable for planting a seedling S. As a result, the seedling planting device 201 can properly plant the seedling S.

[0169] In the seedling planting device 201, the detection unit 270 has a load cell (not shown) that measures the magnitude of the load when the contact portion 271 is lowered and pressed against the ground G. Therefore, the seedling planting device 201 can easily realize a configuration that can properly grasp the layer Gh in the ground G that has a hardness suitable for planting the seedling S.

[0170] The seedling planting device 201 according to the second embodiment plants a seedling S in the ground G on a planting axis P, which is an arbitrary axis. The seedling planting device 201 includes a hole forming unit 250 and a planting unit 260. The hole forming unit 250 includes a drill 251 and a drill moving mechanism 254. The drill 251 forms a hole D in the ground G. The drill moving mechanism 254 moves the drill 251 on the planting axis P, which is an arbitrary axis. The drill moving mechanism 254 also moves the drill 251 between a position on the planting axis P and a position retracted from the planting axis P. The hole forming unit 250 moves the drill 251 along the planting axis P, with the drill moving mechanism 254 moving the drill 251 on the planting axis P, to form a hole D in the ground G on the planting axis P. The planting unit 260 includes a planting chuck 261 and a chuck moving mechanism 263. The planting chuck 261 grips the seedling S. The chuck moving mechanism 263 moves the planting chuck 261 between a position on the planting axis P and a position retracted from the planting axis P. The planting unit 260 uses the chuck moving mechanism 263 to move the planting chuck 261 to the position retracted from the planting axis P, causing the planting chuck 261 to grip the seedling S. The planting unit 260 uses the chuck moving mechanism 263 to move the planting chuck 261 onto the planting axis P, and plants the seedling S gripped by the planting chuck 261 into the hole D formed by the hole forming unit 250.

[0171] This configuration allows the seedling planting device 201 to have improved stability. That is, when planting a seedling S into a hole D formed on the planting shaft P, the seedling planting device 201 can retract the drill 251 from the planting shaft P using the drill movement mechanism 254, and can retract the planting chuck 261 from the planting shaft P using the chuck movement mechanism 263. As a result, the seedling planting device 201 can be configured such that either the drill or the planting chuck does not retract from the planting shaft, i.e., compared to conventional configurations in which either the drill or the planting chuck retracts upward on the planting shaft, the size in the vertical direction can be reduced. Therefore, the seedling planting device 201 can have improved stability.

[0172] The seedling planting device 201 also includes a main slider 240. The main slider 240 is movable along a slider support 241, which serves as a vertically extending slide rail. In the seedling planting device 201, the drill movement mechanism 254 includes a guide rail 250A, which serves as a hole-forming guide rail and is fixedly disposed on the main slider 240, and a first member 254A, which serves as a hole-forming slide member that moves on the guide rail 250A, to move the drill 251 along the planting axis P. The chuck movement mechanism 263 includes a guide rail 260A, which serves as a planting guide rail, and a first member 263A, which serves as a planting slide member that moves on the guide rail 260A, to move the planting chuck 261 along the planting axis P. This allows the seedling planting device 201 to achieve a configuration that further reduces the overall vertical size of the device. In particular, the seedling planting device 201 can ensure the vertical movement of the hole forming unit 250 and the planting unit 260 while keeping the overall height small.

[0173] For example, in a configuration in which only the hole forming unit and the planting unit move vertically and the main slider does not, ensuring the required amount of vertical movement requires an apparatus height that corresponds to that amount of movement. In contrast, in the seedling planting device 201, the main slider 240, which supports the hole forming unit 250 and the planting unit 260 so that they can move vertically, itself is vertically movable. Therefore, the seedling planting device 201 can set the required amount of vertical movement by dividing it between two vertical movement mechanisms, thereby reducing the overall height of the device. As a result, the seedling planting device 201 can maintain a low center of gravity, ensuring stability of the device and enabling even more stable planting operations.

[0174] Furthermore, in the seedling planting device 201, the guide rails 250A and 260A have common specifications. Therefore, the seedling planting device 201 can easily achieve a configuration with reduced vertical size. That is, by making the guide rails 250A, 260A in the hole forming unit 250 and the planting unit 260 have common specifications, such as length, the seedling planting device 201 can avoid a configuration in which, for example, only one of the guide rails protrudes upward. As a result, the seedling planting device 201 can reduce its vertical size. Furthermore, by making the guide rails 250A, 260A have common specifications, the seedling planting device 201 can reduce the number of types of component parts and lower manufacturing costs compared to when the guide rails have different specifications.

[0175] Furthermore, in the seedling planting device 201, the drill moving mechanism 254 moves the drill 251 by rotating it around the rotation axis A203, which is an arbitrary axis parallel to the planting axis P. Therefore, the seedling planting device 201 can realize the drill moving mechanism 254 with a simple configuration.

[0176] Furthermore, in the seedling planting device 201, the chuck moving mechanism 263 moves the planting chuck 261 by rotating it around the rotation axis A204, which is an arbitrary axis parallel to the planting axis P. Therefore, the seedling planting device 201 can realize the chuck moving mechanism 263 with a simple configuration.

[0177] Furthermore, the seedling planting device 201 has a seedling planting unit 204 that is rotatable around rotation axes A201 and A202. The seedling planting unit 204 is maintained in a position such that the planting axis P is vertical. This allows the seedling planting device 201 to perform planting work stably. That is, in the seedling planting device 201, the removal of the seedling S from the seedling placement unit 210, the formation of the hole D in the ground G, and the planting of the seedling S in the hole D are all performed in a constant position with the planting axis P maintained in a vertical position, regardless of the degree of inclination of the ground G. This allows the seedling planting device 201 to perform planting work of the seedling S stably.

[0178] The seedling planting device 201 also includes a remote control device RC. The remote control device RC remotely controls the seedling planting unit 204 to perform a series of operations from picking up the seedling S to planting it in the ground G. Therefore, the seedling planting device 201 can safely perform the planting work of the seedling S from a remote location.

[0179] The present invention is not limited to the first and second embodiments described above with reference to the drawings, and the following embodiments are also included within the technical scope of the present invention.

[0180] (1) It is not essential that the seedling planting device according to the present invention be equipped with a traveling unit. The seedling planting device may be attached to a machine having traveling means, such as a backhoe or a self-propelled mower. When the seedling planting device is equipped with a traveling unit, its configuration is not limited to the configuration exemplified in the above embodiment. The configuration of the traveling unit is not limited to a configuration having crawlers, but may be a configuration having wheels, walking legs, etc. The traveling unit may have traveling means that combines two or more different types of traveling means, such as crawlers, wheels, walking legs, etc.

[0181] (2) It is not essential that the seedling planting device according to the present invention be operated by a remote control device. The seedling planting device may be provided with an operating unit instead of or in addition to a remote control device. The seedling planting device may be a ride-on type that an operator can ride on, or a walk-behind type that the operator operates the device while walking by himself.

[0182] (3) The configuration of the detection unit according to the present invention is not limited to the configuration exemplified in the above embodiment. In the detection unit, the ground contact portion may be provided in the hole forming portion, planting portion, etc., and may rise and fall together with the hole forming portion, planting portion, etc. The ground contact portion may be provided separately from the main slider, hole forming portion, planting portion, etc., and may be capable of rising and falling freely.

[0183] (4) When the detection unit includes a measurement unit, its configuration is not limited to the configurations exemplified in the above embodiments. The measurement unit may, for example, measure a pressing load applied by a lowering means that lowers the ground contact portion, such as the fluid pressure acting on the actuator if the lowering means includes a fluid pressure actuator, or the motor load if the lowering means includes an electric motor. For example, assume that the fluid pressure actuator is a cylinder and the lowering means is configured to press the ground contact portion against the ground by extending or contracting the cylinder. In this configuration, the measurement unit may measure the fluid pressure acting on one of the rod-side pressure chamber and the anti-rod-side pressure chamber in the cylinder. Furthermore, for example, the measurement unit may measure the fluid pressure acting on both the rod-side pressure chamber and the anti-rod-side pressure chamber in a fluid pressure cylinder. In this case, the detection unit can detect a layer of a predetermined hardness based on the differential pressure between the rod-side pressure chamber and the anti-rod-side pressure chamber measured by the measurement unit, thereby improving detection accuracy. [Explanation of symbols]

[0184] 1,201... seedling planting device, 70,270... detection unit, 71,271... ground contact unit, G... ground, Gh... layer of predetermined hardness, S... seedling

Claims

1. A seedling planting device for planting seedlings in the ground, comprising: A seedling planting device having a ground contact part that can be raised and lowered and that contacts the ground, and a detection part that detects a layer of a predetermined hardness in the ground based on the contact of the ground contact part with the ground.

2. The seedling planting device according to claim 1 , wherein the detection unit has a measurement unit that measures the magnitude of the load when the contact part is lowered and pressed against the ground.

3. The ground contact portion is raised and lowered by a fluid pressure actuator, 2. The seedling planting device according to claim 1, wherein the detection unit has a measurement unit that measures the magnitude of fluid pressure acting on the actuator when the contact part is lowered and pressed against the ground.

4. The seedling planting device of claim 1, wherein the detection unit includes a spring that contracts according to the magnitude of the load when the ground contact portion is lowered and pressed against the ground, and a detection unit that detects when the spring has contracted to a predetermined length.

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