Transport vehicle and its control method

Abstract

To provide a transport vehicle that can easily control its travel, stopping, rotation, and lifting of a transport platform.SOLUTION: A transport vehicle 1 travels along a track line 50 and transports a transport platform by lifting it. The transport vehicle includes: a first sensor 11 mounted on a first surface of the transport vehicle and capable of detecting the track line 51; a second sensor 12 mounted on the first surface and capable of detecting an indication line 52 extending in a direction different from the track line; and a third sensor 13 and a fourth sensor 14 mounted on a second surface different from the first surface of the transport vehicle and capable of detecting two detectable portions located at different positions on the transport platform. The transport vehicle travels along the track line detected by the first sensor, stops or rotates in response to detection of the indication line by the second sensor, and lifts the transport platform in a posture in which the two detectable portions can be detected by the third and fourth sensors.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to the control of a transport vehicle such as an automated guided vehicle (AGV). [Background technology]

[0002] Patent Document 1 discloses a method for controlling a transport vehicle, in which a transport vehicle that travels along a magnetic tape and arrives at a turning point reads a two-dimensional code attached to the floor, thereby starting and stopping rotation and adjusting the rotation angle relative to the transported object. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7135416 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method using two-dimensional codes affixed to the floor, as in Patent Document 1, a two-dimensional code must be affixed at each turning point, and the more turning points there are, the more two-dimensional codes that must be affixed to the floor. Furthermore, the two-dimensional codes must be re-affixed every time the travel route or turning points of the transport vehicle are changed. Furthermore, high positional accuracy is required when affixing the two-dimensional barcodes. Thus, the method in Patent Document 1 requires a heavy workload before the transport vehicle can travel.

[0005] The present invention provides a transport vehicle that can easily control the running, stopping, turning, lifting of the transport platform, etc. [Means for solving the problem]

[0006] According to one aspect of the present invention, a transport vehicle travels along a track line and lifts and transports a transport platform. The transport vehicle has a first sensor provided on a first surface of the transport vehicle and capable of detecting the track line, a second sensor provided on the first surface and capable of detecting an indicator line extending in a direction different from the track line, and third and fourth sensors provided on a second surface different from the first surface of the transport vehicle and capable of detecting two detectable portions at different positions on the transport platform. The transport vehicle travels along the track line detected by the first sensor, stops or turns in response to detection of the indicator line by the second sensor, and lifts the transport platform in a position where the two detectable portions are detected by the third and fourth sensors. Note that a transport system including the above-described transport vehicle, track line, and indicator lines also constitutes another aspect of the present invention. [Effects of the Invention]

[0007] According to the present invention, a transport vehicle can be realized that can easily control the running, stopping, turning, lifting of the transport platform, etc. [Brief explanation of the drawings]

[0008] [Figure 1] 1A and 1B are a bottom view, a bottom sensor layout view, and a top sensor layout view of the transport vehicle of the embodiment; [Figure 2] FIG. 2 is a diagram showing the configuration of a sensor in the embodiment. [Figure 3] FIG. 2 is a block diagram showing the configuration of a transport vehicle according to the embodiment. [Figure 4] 3A and 3B are diagrams showing the running, stopping, and turning of the transport vehicle of the embodiment; [Figure 5] 4 is a flowchart showing the control of running, stopping, and turning of the transport vehicle in the embodiment. [Figure 6] 10A and 10B are diagrams showing examples of track lines and indicator lines and a transport platform in an embodiment. [Figure 7] 10A and 10B are diagrams showing the travel of the transport vehicle to the position of the transport platform of the embodiment, the rotation at that position, the lifting of the transport platform, and the transport. [Figure 8] 6 is a flowchart showing the control of the travel of the transport vehicle to the position of the transport platform, the rotation at that position, and the lifting of the transport platform in the embodiment. [Figure 9] FIG. 10 is a diagram showing unloading by a transport vehicle according to an embodiment. [Figure 10] 1 is a diagram showing a transport system including a transport vehicle and a track line according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, an automated guided vehicle (AGV) will be described as a guided vehicle. However, the guided vehicle may also be a manned guided vehicle.

[0010] The AGV 1 travels along a track laid on the floor (not shown) opposite its bottom surface, and transports the transport platform on which the transported object is loaded or to be loaded, while lifting it from the floor. Details of the track and the transport platform will be described later.

[0011] FIG. 1(A) shows the configuration of the bottom side of the AGV 1. The up-down direction in the figure is the front-rear direction (traveling direction) of the AGV 1, and the left-right direction in the figure is the left-right direction of the AGV 1 (direction perpendicular to the traveling direction). Two drive wheels 2 and a motor 3 that drives them are provided on the left and right sides of the bottom of the AGV 1. In addition, two free wheels 4, one on each side, that can rotate 360° around an axis perpendicular to the bottom surface are provided on the front and rear parts of the bottom of the AGV 1. Note that the number of free wheels does not have to be two.

[0012] The AGV 1 moves forward or backward by rotating the two drive wheels 2 in the same direction at the same rotation speed, and turns around the center O of the body by rotating the two drive wheels 2 in opposite directions at the same rotation speed. The direction of travel can also be corrected by changing the rotation speed of the two drive wheels 2 when moving forward or backward. The center O of the body of the AGV 1 is the point where the center axis A1 of the body in the left-right direction and the center axis A2 of the body in the front-to-rear direction intersect. The central axes of rotation of the two drive wheels 2 are located at a position corresponding to the center axis A2 (a position overlapping the center axis A2 when viewed from the bottom).

[0013] FIG. 1(B) shows the sensor installation surface (first surface) on the bottom side of the AGV 1. A first sensor 11 is provided at the center of the front of the bottom sensor installation surface. Two second sensors 12 are provided at two locations, one on the left side and one on the right side of the bottom sensor installation surface. The first sensor 11 is arranged so that its center in the left-right direction, i.e., its longitudinal direction, corresponds to the central axis A1 (a position overlapping the central axis A1 when viewed from the bottom). The second sensor 12 is arranged so that its center in the front-rear direction, i.e., its longitudinal direction, corresponds to the central axis A2 (the central axis of rotation of the drive wheels 2). Five non-contact sensors, which will be described later, are arranged in the longitudinal direction of the first and second sensors 11 and 12, with the center of the central non-contact sensor of the five non-contact sensors being located at the center of the sensors. Details of the first and second sensors 11 and 12 will be described later.

[0014] As shown in FIG. 1(B), the two second sensors 12 are disposed at positions avoiding the two drive wheels 2, respectively.

[0015] FIG. 1(C) shows the sensor installation surface (second surface) on the top side, which is opposite to the bottom side of the AGV 1. A third sensor 13 is provided in the center of the front of the top sensor installation surface. Two fourth sensors 14 are provided in two locations, one on the left side and one on the right side of the top sensor installation surface. The third sensor 13 is arranged so that its center in the left-right direction corresponds to the central axis A1. The fourth sensor 14 is arranged so that its center in the front-rear direction corresponds to the central axis A2 (the rotational center axis of the drive wheels 2). Details of the third and fourth sensors 13 and 14 will be described later. The number and spacing of the second and fourth sensors may vary depending on the object to be detected.

[0016] FIG. 2A shows the configuration of the first to fourth sensors 11 to 14. Each sensor is composed of a substrate 20 and five non-contact sensors 21 to 25 mounted on the substrate surface and aligned at predetermined intervals along the longitudinal direction of the substrate 20. As shown in FIGS. 2B and 2C, each of the non-contact sensors 21 to 25 can detect a detection object OBJ (such as a track or a detection target portion of a conveyance platform) without contact. For example, if photosensors are used as the non-contact sensors 21 to 25, five light sources such as LEDs (not shown) are mounted on the substrate 20 to correspond to each of the non-contact sensors 21 to 25. The photosensors receive light emitted from the corresponding light sources and reflected by the light-reflective detection object OBJ (turning ON, indicating detection). This allows the presence of the detection object OBJ at a position opposite the photosensor. When the photosensor does not receive light reflected from the detection object OBJ (it turns OFF, indicating no detection), it can detect that the detection object OBJ is not present in the position opposite the photosensor. If the detection object OBJ has magnetism, magnetic sensors may be used as the non-contact sensors 21 to 25.

[0017] In this embodiment, taking the first sensor 11 and the second sensor 12 as an example, when the non-contact sensors 21 and 25 at both ends of the five non-contact sensors 21 to 25 are OFF and the non-contact sensors 22 to 24 between them are ON as shown in FIG. 2(B), it is detected that the central axis A (A1, A2) of the AGV 1 is located on the widthwise center B of the object to be detected OBJ. Also, as shown in FIG. 2(C), when the leftmost and adjacent right non-contact sensors 21 and 22 of the five non-contact sensors 21 to 25 are OFF and the other non-contact sensors 23 to 25 are ON, it is detected that the central axis A of the AGV 1 is located to the left of the widthwise center B of the object to be detected OBJ. In this way, the first to fourth sensors 11 to 14 each output a signal according to the combination of ON and OFF of the five non-contact sensors 21 to 25, and this is called the detection state of each of the first to fourth sensors 11 to 14.

[0018] In this embodiment, the first to fourth sensors 11 to 14 are described as all having the same number of non-contact sensors arranged at equal intervals, but the number and spacing of the non-contact sensors may be varied depending on the width of the object to be detected by the sensors.

[0019] Fig. 3 shows the overall configuration of the AGV 1. Here, as shown in Fig. 6(A), a case will be described in which a plurality of track lines 50 (51, 52) are laid out in a grid pattern. In Fig. 6(A), track line 51 extending in the vertical direction (depth direction) is perpendicularly intersected by track line 52 extending in the horizontal direction. A light-reflective material such as aluminum tape is used as track line 50.

[0020] 10 shows an example of the configuration of a transport system including a plurality of track lines 50 arranged in a grid pattern, an AGV 1, and a plurality of transport platforms 60 arranged at some of the intersections of the track lines 50. The transport system is used, for example, as a two-dimensional automated warehouse system for storing and retrieving transported items such as various parts.

[0021] The AGV 1 starts traveling from the entrance, travels along the track line 50 as shown by the arrow in the figure to the position of the designated carrier platform (shown hatched) 60, turns around, and lifts the carrier platform 60 from below.

[0022] FIG. 6(D) shows a transport platform 60. The transport platform 60 has an outer frame 61, inner frames 62 and 63 that cross (orthogonally intersect) inside the outer frame 61, and legs 64 that extend downward from the four corners of the outer frame 61. The inner frames 62 and 63 are fixed to the center of the outer frame 61 in the left-right direction and the center of the front-rear direction, respectively, and the intersection position of the inner frames 62 and 63 is the center of the transport platform 60. Note that while the figure shows a case where the outer frame 61 is rectangular, the outer frame may have a shape other than rectangular. Furthermore, the intersection position of the inner frame with respect to the outer frame may be shifted from the center in the left-right direction or the front-rear direction to suit the transported object, for example.

[0023] An object to be transported (not shown) can be placed on the loading surface formed by the outer frame 61 and the inner frames 62, 63. The legs 64 contact the floor surface on which the track lines 51, 52 are laid, forming a space between the floor surface and the loading surface into which the AGV 1 can enter. The AGV 1 travels and turns within this space, lifting the transport platform 60 with the lift mechanism 35. The AGV 1 then travels along the track lines 50 toward the exit as shown by the arrow in FIG. 10, transporting the transport platform 60.

[0024] 3, the first sensor 11 of the AGV 1 can detect a track line 51, which is one of the track lines 50 and extends in the traveling direction of the AGV 1. The second sensor 12 can detect a track line 52 that extends in a direction different from the traveling direction (a direction perpendicular to the track line 51). The AGV 1 can also travel along the track line 52, in which case the first sensor 11 detects the track line 52 and the second sensor 12 detects the track line 51. When the AGV 1 travels along the track line 51, the track line 52 corresponds to the instruction line, and when the AGV 1 travels along the track line 52, the track line 51 corresponds to the instruction line.

[0025] The third sensor 13 can detect the inner frame 62 as a detected part extending in the traveling direction of the AGV 1 on the conveying platform 60. The fourth sensor 14 can detect the inner frame 63 as a detected part extending in a direction perpendicular to the traveling direction of the AGV 1 on the conveying platform 60. The third sensor 13 and the fourth sensor 14 can detect the inner frame 63 and the inner frame 62, respectively, when the AGV 1 turns 90°.

[0026] The control unit 30 is configured by a computer including a CPU and the like, and controls the AGV 1 according to a program. The control unit 30 controls the left and right motors 3 that rotate the left and right drive wheels 2 in accordance with the detection state of the track line 51 by the first sensor 11 (the combination of ON and OFF of the non-contact sensors 21 to 25 as described above), thereby causing the AGV 1 to travel along the track line 51. Specifically, as shown in FIG. 2(B), the control unit 30 controls the motors 3 so that the central axis A1 of the AGV 1 is positioned on the width center B of the track line 51, which is the detected object OBJ.

[0027] The control unit 30 also stops the AGV 1 from traveling or rotates the AGV 1 by stopping or reversing the rotation of the left and right motors 3 in response to the detection of the track line (indicator line) 52 by the second sensor 12. When stopping the AGV 1, the control unit 30 controls the left and right motors 3 in response to the detection state of the track line 52 by the second sensor 12 so that the central axis A2 of the AGV 1 is parallel to the track line 52 and positioned at the center of the width of the track line 52, that is, so that the posture (position and turning angle) of the AGV 1 becomes a target stopping posture after stopping traveling. The target stopping posture at this time is a posture in which the center (reference point) O of the AGV 1 is positioned at the center of the intersection of the track lines 51 and 52. This corrects any deviation in the posture of the AGV 1 from the target stopping posture after stopping traveling.

[0028] On the other hand, when turning the AGV 1 by 90°, the control unit 30 controls the left and right motors 3 in accordance with the detection state of the track line 51 as a turning stop instruction line by the second sensor 12 so that the central axis A2 of the AGV 1 is parallel to the track line 51 and positioned at the center of the width of the track line 51, i.e., so that the posture of the AGV 1 becomes the target stopping posture after turning by 90°. The target stopping posture at this time is also a posture in which the center O of the AGV 1 is positioned at the center of the intersection of the track lines 51 and 52. This corrects the posture deviation of the AGV 1 from the target stopping posture after turning by 90°.

[0029] In addition, the AGV 1 can also rotate 180 degrees or 270 degrees, and in these cases, the positional deviation of the AGV 1 from the target stopping position after the rotation is corrected according to the detection state of the track lines 52, 51 by the second sensor 12.

[0030] Furthermore, when the AGV 1 enters the space below the conveyance platform 60, the control unit 30 controls the left and right motors 3 in accordance with the detection state of the inner frame 62 by the third sensor 13, thereby aligning the central axis A1 of the AGV 1 with the central axis of the inner frame 62. Furthermore, the control unit 30 stops the left and right motors 3 in accordance with the detection state of the inner frame 63 by the fourth sensor 14. After this, when the AGV 1 turns 90°, the control unit 30 controls the left and right motors 3 in accordance with the detection state of the inner frame 63 by the third sensor 13 and the detection state of the inner frame 62 by the fourth sensor 14, so that the central axes A1 and A2 of the AGV 1 are aligned with the width centers of the inner frames 63 and 62, respectively, i.e., so that the posture of the AGV 1 becomes the target lifting posture. The target lifting posture is a posture in which the center (reference point) O of the AGV 1 is aligned with the center of the conveyance platform 60. This corrects the posture deviation of the AGV 1 from the target lifting posture after the 90° turn.

[0031] Furthermore, when the AGV 1 turns 180°, the control unit 30 controls the left and right motors 3 so that the central axes A1 and A2 of the AGV 1 are aligned with the width centers of the inner frames 62 and 63, respectively, in accordance with the detection state of the inner frame 62 by the third sensor 13 and the detection state of the inner frame 63 by the fourth sensor 14. In this way, the positional deviation of the AGV 1 from the target lifting position after the 180° turn is corrected.

[0032] When the AGV 1 is in the target lifting posture, the lift mechanism 35 can use the driving force of a lift motor (not shown) to lift or lower the transport platform 60 relative to the floor surface. The control unit 30 controls the driving of the lift motor.

[0033] Figures 4(A) to (D) show the AGV 1 running, stopping, turning, and running again. The flowchart in Figure 5(A) shows the control flow from when the AGV 1 runs until it stops, and the flowchart in Figure 5(B) shows the control flow when the AGV 1 turns after stopping. The control unit 30 executes the processes for each control according to the program.

[0034] In step S101 of FIG. 5(A), the control unit 30 causes the AGV 1 to travel along the track line 51 by the first sensor 11 detecting the track line 51 as shown in FIG. 4(A).

[0035] Next, in step S102, the control unit 30 receives an instruction to stop the traveling of the AGV 1 in response to the second sensor 12 next detecting the track line 52. This stop instruction is notified to the control unit 30 by wireless communication via a communication element such as an RF tag (not shown) provided in front of the track line 52. The same applies to other instructions described later.

[0036] Next, in step S103, the control unit 30 confirms that the second sensor 12 has detected the track line 52 as the instruction line, as shown in Fig. 4(B). In response to this, in step S104, the control unit 30 stops the traveling of the AGV 1. Furthermore, the control unit 30 corrects the posture deviation of the AGV 1 from the target stopping posture after the traveling has stopped, in accordance with the detection state of the track line 52 by the second sensor 12, as described above.

[0037] 5B, the control unit 30 receives an instruction to turn 90 degrees after stopping traveling. In response to this, in step S112, the control unit 30 starts turning the AGV 1 90 degrees.

[0038] Next, in step S113, the control unit 30 confirms that the second sensor 12 has detected the trajectory line 51 as the instruction line after the turn, as shown in Fig. 4(C). In response to this, in step S114, the control unit 30 stops the 90° turn of the AGV 1. Furthermore, the control unit 30 corrects the posture deviation of the AGV 1 from the target stopping posture after the 90° turn, depending on the detection state of the trajectory line 51 by the second sensor 12, as described above.

[0039] Thereafter, the control unit 30 causes the first sensor 11 to detect the track line 52, as shown in FIG. 4(D), and causes the AGV 1 to travel along the track line 52.

[0040] Figures 7(A) to 7(E) show the AGV 1 traveling to the position of the carrier 60, stopping, turning 90 degrees twice, and then lifting and transporting the carrier 60. The flowchart in Figure 8(A) shows the control flow from when the AGV 1 travels toward the carrier 60 until it stops at the position of the carrier 60, and the flowchart in Figure 8(B) shows the control flow when the AGV 1 turns. Furthermore, the flowchart in Figure 8(C) shows the control flow when the AGV 1 lifts the carrier 60.

[0041] In step S201 of Figure 8(A), the control unit 30 confirms that the third sensor 13 has detected the inner frame (first detection part) 62 of the conveying platform 60 while the AGV 1 is traveling toward the conveying platform 60 as shown in Figure 7(A).

[0042] Next, in step S202, the control unit 30 receives an instruction to stop the traveling of the AGV 1 in response to the fourth sensor 14 next detecting the inner frame (second detection target portion) 63.

[0043] Next, in step S203, the control unit 30 confirms that the fourth sensor 14 has detected the inner frame 63 of the conveyance platform 60, as shown in Fig. 7(B). In response to this, in step S204, the control unit 30 stops the travel of the AGV 1.

[0044] 8B, the control unit 30 receives an instruction to turn 90 degrees after stopping traveling. In response to this, in step S212, the control unit 30 starts turning the AGV 1 90 degrees.

[0045] Next, in step S213, the control unit 30 confirms that the fourth sensor 14 has detected the inner frame (first detection target) 62 of the conveyance platform 60, as shown in Fig. 7(C). In response to this, in step S214, the control unit 30 stops the 90° rotation of the AGV 1. Furthermore, the control unit 30 corrects the positional deviation of the AGV 1 from the target stopping position after the 90° rotation, in accordance with the detection state of the inner frame 63 by the third sensor 13 and the detection state of the inner frame 62 by the fourth sensor 14, as described above.

[0046] Next, although not shown in the flowchart, the control unit 30 receives an instruction to rotate another 90° and starts the 90° rotation of the AGV 1 to rotate 180°. Then, the control unit 30 confirms that the fourth sensor 14 has detected the inner frame (second detection target portion) 63 of the conveyance platform 60, as shown in FIG. 7(D). In response to this, the control unit 30 stops the 90° rotation of the AGV 1. Furthermore, the control unit 30 corrects the positional deviation of the AGV 1 from the target stopping position after the 180° rotation, in accordance with the detection state of the inner frame 62 by the third sensor 13 and the detection state of the inner frame 63 by the fourth sensor 14, as described above.

[0047] In step S221 of FIG. 8C after the 180° rotation, the control unit 30 drives the lift motor of the lift mechanism 35 to lift the transport platform 60 in response to receiving the lift-up instruction.

[0048] When the lifting of the conveyance platform 60 is completed, the control unit 30 stops the driving of the lift motor in step S222. Thereafter, the control unit 30 causes the AGV 1 to travel along the track line 51 as shown in FIG. 7(E).

[0049] 9(A) to 9(D) show the AGV 1 transporting the carrier 60, stopping at a designated unloading position, and then moving on after unloading the carrier 60. The flowchart in Fig. 5(A) shows the control flow from when the AGV 1 transports the carrier 60 until it stops at the unloading position, and the flowchart in Fig. 5(C) shows the control flow when the AGV 1 unloads the carrier 60.

[0050] In step S101 of FIG. 5(A), the control unit 30 causes the first sensor 11 to detect the track line 51 as shown in FIG. 9(A), thereby causing the AGV 1 to travel along the track line 51 (transporting the carrier 60).

[0051] Next, in step S102, the control unit 30 receives an instruction to stop the traveling of the AGV 1 in response to the second sensor 12 next detecting the track line 52 (reaching the designated unloading position).

[0052] Next, in step S103, the control unit 30 confirms that the second sensor 12 has detected the track line 52 as the instruction line, as shown in Fig. 9(B). In response to this, in step S104, the control unit 30 stops the traveling of the AGV 1. Furthermore, the control unit 30 corrects the posture deviation of the AGV 1 from the target stopping posture after the traveling has stopped, in accordance with the detection state of the track line 52 by the second sensor 12, as described above.

[0053] In step S121 of FIG. 5C, the control unit 30 drives the lift motor of the lift mechanism 35 to lower the transport platform 60 in response to receiving a lift-down instruction at the unloading position.

[0054] When the lowering of the conveyance platform 60 is completed, the control unit 30 stops the driving of the lifting motor in step S122. Thereafter, the control unit 30 causes the AGV 1 to travel along the forward track line 51, as shown in Fig. 9(D). At this time, the AGV 1 may be rotated 90° to travel along the track line 52, or may be rotated 180° to travel back along the track line 51.

[0055] Figures 6(B) and (C) show examples of track lines and indicator lines different from those shown in Figure 6(A). Figure 6(B) shows an example in which a short indicator line 53 intersects with track line 50 (51). In this example, AGV 1 travels along track line 50 detected by first sensor 11, and only stops or turns in response to detection of indicator line 53 by second sensor 12.

[0056] 6(C) shows an example in which a short indicator line 54 is provided at a position away from the track line 50 (51). In this example, the AGV 1 travels along the track line 50 detected by the first sensor 11, and only stops in response to the detection of the indicator line 54 by the second sensor 12.

[0057] According to the above-described embodiment, a conveyance system can be constructed simply by laying track lines (including indicator lines). Specifically, the first and second sensors mounted on the conveyance vehicle detect the track lines and indicator lines to control the travel, stopping, and turning of the conveyance vehicle, and the third and fourth sensors detect the detected portion of the conveyance platform to control the attitude of the conveyance vehicle relative to the conveyance platform and the lifting of the conveyance platform. Therefore, compared to conventional methods that require attaching a two-dimensional code at each direction change point, re-attaching the two-dimensional code every time the travel route or direction change point is changed, and require high positional accuracy of the two-dimensional code, it is possible to easily control the travel, stopping, and turning of the conveyance vehicle, as well as the lifting and lowering of the conveyance platform, with high precision.

[0058] In the above embodiment, an AGV equipped with a control unit that controls travel, stopping, turning, and lifting of the carrier platform in response to detection by the first to fourth sensors has been described, but a control device equivalent to the control unit may be provided separately from the AGV, and the control device may control the travel, stopping, turning, and lifting of the carrier platform of the AGV via wireless communication. Furthermore, the first to fourth sensors may be mounted on the manned guided vehicle, and an operator may control the travel, stopping, turning, and lifting of the carrier platform of the manned guided vehicle while monitoring detection by the first to fourth sensors. In this case, there is no need to mount a control unit on the manned guided vehicle.

[0059] The embodiments described above are merely representative examples, and various modifications and alterations are possible to each embodiment when implementing the present invention. [Explanation of symbols]

[0060] 1. Automated guided vehicles (AGVs) 2 drive wheels 3 motors 4 Freewheel 11 First sensor 12 Second sensor 13 Third Sensor 14 4th sensor 30 Control Unit 35 Lift mechanism 50 Trajectory line 51 Trajectory line 52 Trajectory line (indication line) 60 transport platform

Claims

1. A transport vehicle that travels along a track line and lifts and transports a transport platform, a first sensor provided on a first surface of the transport vehicle and capable of detecting the track line; a second sensor provided on the first surface and capable of detecting an indicator line extending in a direction different from the trajectory line; a third sensor and a fourth sensor that are provided on a second surface of the transport vehicle that is different from the first surface and that are capable of detecting two detection targets that are located at different positions on the transport platform; traveling along the track line detected by the first sensor; The robot stops or turns in response to the detection of the indicator line by the second sensor, The transport vehicle is characterized in that the transport platform is lifted in a position where the two detection target portions are detected by the third and fourth sensors.

2. 2. The transport vehicle according to claim 1, wherein the indicator line is another track line that intersects with the track line.

3. a control means for controlling the transport vehicle; The control means controls the transport vehicle. running the vehicle along the track line detected by the first sensor; stopping or turning in response to the detection of the indicator line by the second sensor; 2. The transport vehicle according to claim 1, wherein the transport platform is controlled to be lifted in a position where the two detection target portions are detected by the third and fourth sensors.

4. 4. The transport vehicle according to claim 3, wherein the control means controls the transport vehicle so as to correct a positional deviation of the transport vehicle from a target stopping position in accordance with a detection state of the indicator line by the second sensor.

5. the second sensor is capable of detecting the track line before turning as a turning stop instruction line after the guided vehicle starts turning, The transport vehicle according to claim 3, characterized in that the control means controls the transport vehicle so as to correct a positional deviation of the transport vehicle from a target stopping position depending on the detection state of the turning stop instruction line by the second sensor.

6. The transport vehicle has two drive wheels in a second direction perpendicular to a first direction that is a traveling direction, and travels by rotating the two drive wheels in the same direction, and turns by rotating the two drive wheels in opposite directions at the same rotation speed, the first sensor is provided at the center in the second direction, 2. The transport vehicle according to claim 1, wherein the second sensor is provided at a position corresponding to a central axis of rotation of the two drive wheels.

7. The transport vehicle described in claim 3, characterized in that the control means controls the transport vehicle to correct a positional deviation of the transport vehicle from a target lifting position depending on the detection state of the two detectable parts by each of the third and fourth sensors after the transport vehicle stops moving or turns.

8. The transport vehicle has two drive wheels in a second direction perpendicular to a first direction that is a traveling direction, and travels by rotating the two drive wheels in the same direction, and turns by rotating the two drive wheels in opposite directions at the same rotation speed, the third sensor is provided at the center in the second direction, 2. The transport vehicle according to claim 1, wherein the fourth sensor is provided at a position corresponding to a central axis of rotation of the two drive wheels.

9. each of the first, second, third, and fourth sensors includes a plurality of non-contact sensors capable of detecting a detection target; 8. The transport vehicle according to claim 4, wherein the detection state is a combination of detection and non-detection of the object by the plurality of non-contact sensors.

10. 2. The carrier vehicle according to claim 1, wherein the first and second sensors are capable of detecting the track line and the indicator line, respectively, which extend in directions perpendicular to each other.

11. 2. The transport vehicle according to claim 1, wherein the third and fourth sensors are capable of detecting the two detection targets extending in directions perpendicular to each other.

12. A transport vehicle according to any one of claims 1 to 11; The track line; A conveying system comprising the indicator line.

13. A method for controlling a transport vehicle that travels along a track line and lifts and transports a transport platform, comprising: a first sensor capable of detecting the track line is provided on a first surface of the transport vehicle; a second sensor capable of detecting an indication line extending in a direction different from the track line is provided on the first surface; and a third sensor and a fourth sensor capable of detecting two detection targets at different positions on the transport platform are provided on a second surface of the transport vehicle different from the first surface; The transport vehicle, running the vehicle along the track line detected by the first sensor; stopping or turning in response to the detection of the indicator line by the second sensor; a control method for controlling the conveyance table to be lifted in a position where the two detection target portions are detected by the third and fourth sensors;

14. A program causing a computer of the transport vehicle to execute processing according to the control method of claim 13.

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