Automated guided vehicles

Abstract

To provide a four-wheel automatic carrier vehicle capable of obtaining low floor while securing grounding property of driving wheels.SOLUTION: An automatic carrier vehicle includes: a pair of driving wheels 14RL and 14RR; a pair of auxiliary wheels 14FL and 14FR; a pair of arms 42L and 42R extending in the front to back direction, supported to freely oscillate around an axial line extending in the vehicle width direction to a vehicle body 12 on one end and retaining the driving wheels 14RL and 14RR rotatably on the other end; drive sources 34L and 34R for independently driving the driving wheels 14RL and 14RR, respectively; and a control device 60 capable of causing itself to travel by controlling the driving sources 34L and 34R as well as varying a proceeding direction by differing rotational speed of each of the driving wheels 14RL and 14RR. Each of the pair of arms 42L and 42R supports the vehicle body 12 by abutting one portion of the vehicle body 12 from below when travelling on a flat road surface.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an automated guided vehicle. [Background technology]

[0002] The following Patent Documents 1 and 2 describe automatic guided vehicles (AGVs) that are automatically driven by computer control. The automatic guided vehicles described in the following Patent Documents 1 and 2 are configured such that the drive wheels are biased downward by suspensions to follow uneven road surfaces. The automatic guided vehicles described in the following Patent Documents 1 and 2 have six wheels, with auxiliary wheels on both the front and rear of the drive wheels. The drive wheel located in the middle is biased by a suspension, making it easier for all wheels to contact the ground, enabling stable travel. Furthermore, the automatic guided vehicle described in the following Patent Document 2 is configured such that at least a portion of the steering mechanism is located between the upper and lower ends of the drive wheels in the vertical direction in order to achieve vertical compactness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-24749 [Patent Document 2] JP 2018-140700 A Summary of the Invention [Problem to be solved by the invention]

[0004] The automated guided vehicles described in the above Patent Documents 1 and 2 have suspensions that extend in the vertical direction, which means that it is necessary to ensure vertical dimensions, which makes it difficult to reduce the vertical size of the automated guided vehicles, or in other words, to make them low-floor.

[0005] The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a four-wheeled automated guided vehicle that can be made low-floor while ensuring the ground contact of the drive wheels. [Means for solving the problem]

[0006] In order to solve the above problems, the automated guided vehicle of the present invention comprises: A four-wheeled automated guided vehicle, The car body and a pair of drive wheels disposed on each of the left and right sides of the vehicle body and driven independently of each other; a pair of auxiliary wheels disposed on the left and right sides of the vehicle body either in front of or behind the pair of drive wheels and rotatably held; a pair of arms each extending in a front-rear direction, supported at one end so as to be swingable about an axis extending in a vehicle width direction relative to the vehicle body, and rotatably holding the drive wheel at the other end; a drive source that independently drives each of the pair of drive wheels; a control device that controls the drive source to drive the automated guided vehicle and that changes the direction of travel of the automated guided vehicle by varying the rotation speed of each of the pair of drive wheels; Equipped with When the automated guided vehicle travels on a flat road surface, each of the pair of arms abuts against a part of the vehicle body from below to support the vehicle body.

[0007] The automated guided vehicle disclosed in the present application is automatically driven under computer control in factories and other locations, and is generally designed to travel on flat road surfaces. However, even on such flat surfaces, small grooves, recesses, and the like exist. Conventionally, suspensions are provided to bias the drive wheels downward so that the wheels can follow such surfaces. However, in the automated guided vehicle disclosed in the present application, the arms holding the drive wheels are supported swingably relative to the vehicle body. Therefore, when one of a pair of drive wheels passes over a groove or recess, the arm corresponding to that drive wheel moves downward from the vehicle body, allowing the drive wheel to easily follow the groove or recess. In particular, the automated guided vehicle disclosed in the present application has four wheels, two of which are drive wheels, and changes its direction of travel depending on the difference in rotational speed between the pair of drive wheels. Therefore, if one drive wheel leaves the road surface, the vehicle's travel will be hindered. However, the automated guided vehicle disclosed in the present application ensures that all four wheels stay firmly on the ground, thereby achieving stable travel.

[0008] In the above configuration, the vehicle body may be provided with a stopper mechanism that abuts against the arm at a position where the arm is parallel to the road surface when the automated guided vehicle is traveling on a flat road surface, thereby preventing the arm from swinging upward.

[0009] In an automated guided vehicle of this configuration, when it is normally running on a flat road, the arm extends horizontally, so the mechanism for supporting one end of the arm on the vehicle body can easily be contained within the height dimension of the drive wheel, making it suitable for low-floor automated guided vehicles.

[0010] In the above configuration, the height dimension of the vehicle body is smaller than the outer diameter of the drive wheels, the pair of drive wheels are arranged outside the vehicle body, and the pair of arms can be configured to abut against the vehicle body at a position where the upper ends of the pair of drive wheels are approximately at the same height as the upper surface of the vehicle body.

[0011] In an automated guided vehicle with this configuration, the outer diameter of the drive wheels is the same as the height of the automated guided vehicle, thereby achieving a low floor. In this automated guided vehicle with this configuration, when an object to be transported is placed above the drive wheels, it is desirable that the upper ends of the pair of drive wheels be configured to be slightly below the upper surface of the vehicle body.

[0012] In the above configuration, the vehicle body may be provided with a pair of shafts that are held in the vehicle body in a position extending in the vehicle width direction and rotatable around an axis, and each of the pair of arms may be fixed to the shaft at one end.

[0013] In an automated guided vehicle with this configuration, one end of the arm is fixed to a longitudinal shaft, so the load acting on one end of the arm can be distributed across the shaft, improving durability.

[0014] In the above configuration, the drive source is configured to include a pair of drive motors provided for each of the pair of drive wheels, which drive the drive wheels by rotating motor shafts provided coaxially with the drive wheels, and each of the pair of arms can be configured to hold the drive motor and the drive wheel at the other end.

[0015] This type of automated guided vehicle is configured as a so-called in-wheel motor type, where the drive motors for each drive wheel are also held on the arms together with the drive wheels. Because the weight held by the arms is large, it is possible to improve the ability of the drive wheels to follow grooves and recesses, i.e., to make the wheels more stable when traveling.

[0016] In the above configuration, an induction detection sensor is provided on the front side of the vehicle body to recognize an induction device that is installed on the road surface and that guides the automatic guided vehicle, and the control device causes the automatic guided vehicle to run along the induction device, and the pair of auxiliary wheels can be configured as front wheels and the pair of drive wheels as rear wheels.

[0017] An automated guided vehicle with this configuration is a so-called route guided vehicle that moves along a guide such as a magnetic tape, a light reflective tape, or an electromagnetic induction cable. This route guided automated guided vehicle controls the direction of travel of the vehicle, that is, controls the difference in rotational speed between a pair of drive wheels, based on the detection value of the guide detection sensor. With this automated guided vehicle, the drive wheels are rear wheels, so that a sufficient time can be secured between the time of detection by the guide detection sensor and the transmission of a control signal to the drive source, allowing the vehicle to travel reliably along the guide. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a four-wheeled automated guided vehicle that can be made low-floor while ensuring the ground contact of the drive wheels. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a plan view of an automated guided vehicle according to an embodiment of the present invention; [Figure 2] Side view of an automated guided vehicle [Figure 3] Cross-sectional view of an automated guided vehicle from the rear [Figure 4] A diagram showing an automated guided vehicle from a bottom view [Figure 5] A side view of an automated guided vehicle traveling on a flat road [Figure 6] A plan view showing an example of an automated guided vehicle traveling. [Figure 7] A side view showing one of the drive wheels of the automated guided vehicle passing through a recess. DETAILED DESCRIPTION OF THE INVENTION

[0020] An automated guided vehicle 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. The automated guided vehicle 10 of this embodiment is used, for example, to tow a cart or other object to be transported on a production line in a factory. The automated guided vehicle 10 is automatically driven under computer control and is also called an unmanned guided vehicle or an AGV (Automatic Guided Vehicle). Note that in some of the drawings, directions are indicated using the symbols Fr, Rr, L, R, U, and D, which respectively represent the front side, rear side, left side, right side, upper side, and lower side of the automated guided vehicle 10.

[0021] The automated guided vehicle 10 includes a frame 12, which is a vehicle body and has a generally rectangular shape in a plan view, and four wheels 14FL, 14FR, 14RL, and 14RR arranged on the front, rear, left, and right sides of the frame 12. As will be explained in detail later, of the four wheels, two rear wheels 14RL and 14RR are drive wheels, and two front wheels 14FL and FR are auxiliary wheels (driven wheels).

[0022] The frame 12 is made up of a main body 16, which is a rectangular portion on the front side and holds the four wheels 14FL, 14FR, 14RL, and 14RR, a storage section 17 located on the rear side and storing a control device (described later), and a connecting section 18 that connects the main body 16 and the storage section 17. While the main body 16 and the storage section 17 have the same dimensions in the vehicle width direction, the dimension of the connecting section 18 in the vehicle width direction is smaller than the dimensions of the main body 16 and the storage section 17 in the vehicle width direction. In other words, as shown in FIG. 1, the frame 12 has a recessed shape at both ends in the vehicle width direction in a middle portion in a plan view.

[0023] Furthermore, the frame 12 has an upper surface 12A that extends in a flat plane, and when the automated guided vehicle 10 is placed on a flat road surface, the upper surface 12A is substantially parallel (substantially horizontal) to the road surface. Incidentally, the body of the automated guided vehicle 10 is formed only by the frame 12, but it may also be configured to include covers that cover the sides, a top plate that covers the top surface, and the like.

[0024] As described above, four wheels 14FL, 14FR, 14RL, and 14RR are disposed on main body 16 of frame 12. Specifically, two front wheels 14FL, 14FR constitute casters 20L, 20R, and are held by wheel holder 22 as shown in FIGS. 2 and 4. That is, automated guided vehicle 10 includes a pair of casters 20L, 20R, which are attached to the front side of main body 16 at a distance in the vehicle width direction. Wheel holder 22 holds each front wheel 14FL, 14FR of caster 20L, 20R so that it can rotate about an axis extending generally horizontally, and wheel holder 22 itself can rotate about an axis extending vertically, allowing the orientation of front wheels 14FL, 14FR, specifically, the angle relative to the front-to-rear direction of frame 12, to be freely changed. That is, the front wheels 14FL, 14FR are steered in accordance with the traveling direction of the automated guided vehicle 10, and function as so-called driven wheels.

[0025] Meanwhile, rear wheels 14RL, 14RR are wheels that constitute drive wheel units 30L, 30R, and the automated guided vehicle 10 is equipped with a pair of drive wheel units 30L, 30R. The pair of drive wheel units 30L, 30R are provided on the rear side of the main body 16, and when the automated guided vehicle 10 is placed on a flat road surface, the rear wheels 14RL, 14RR are held outside the frame 12, more specifically, on the left and right sides of the connecting portion 18 behind the main body 16. In other words, the rear wheels 14RL, 14RR are located in recessed areas on the left and right sides of the frame 12 in a plan view, as shown in FIG. 1.

[0026] Next, the drive wheel units 30L, 30R will be described in detail. As shown in Figures 3 and 4, the drive wheel units 30L, 30R are of an in-wheel motor type and include axle cases 32L, 32R that rotatably hold the axles of the rear wheels 14RL, 14RR about axes extending horizontally, and drive motors 34L, 34R that drive the rear wheels 14RL, 14RR. Housings of the drive motors 34L, 34R are fixed to the axle cases 32L, 32R on the opposite side from the rear wheels 14RL, 14RR (inner side in the vehicle width direction), and drive the rear wheels 14RL, 14RR by rotating a motor shaft 36 that is fixed coaxially to the axles of the rear wheels 14RL, 14RR.

[0027] The drive wheel units 30L, 30R also include shafts 40L, 40R held by the main body 16 of the frame 12, and arms 42L, 42R whose front ends (one ends) are fixed to the shafts 40L, 40R and extend rearward. As shown in Fig. 4, the shafts 40L, 40R are arranged extending in the vehicle width direction with their inner end faces facing each other, and are each held rotatably about their own axis by two shaft holders 44 provided at an interval in the vehicle width direction. The front ends of the arms 42L, 42R are fixed to the outer ends of the shafts 40L, 40R in the vehicle width direction.

[0028] The axle cases 32L, 32R are fixed to the rear ends of the arms 42L, 42R, and the arms 42L, 42R support the rear wheels 14RL, 14RR and the drive motors 34L, 34R. As described above, the front ends of the arms 42L, 42R are fixed to the shafts 40L, 40R, which are rotatably supported about axes extending in the vehicle width direction, and are therefore supported so as to be swingable about the front ends. In other words, the rear wheels 14RL, 14RR are supported by the shafts 40L, 40R and the arms 42L, 42R so as to be swingable about the front ends of the arms 42L, 42R.

[0029] Stopper mechanisms 50L, 50R are provided between the arms 42L, 42R and the frame 12. As shown in Figures 1 and 2, the stopper mechanisms 50L, 50R consist of a plate 52 fixed to a member constituting the main body 16 in a state where it protrudes rearward from the rear end of the main body 16, a bolt 53 fixed in a state where it passes through the plate 52, and a buffer material 54 fixed to the lower end of the bolt 53. As shown in Figure 1, the bolt 53 and the buffer material 54 are provided in a position where they overlap the arms 42L, 42R in a plan view, and the arms 42L, 42R abut against them from below. 5, when the automated guided vehicle 10 travels on a flat road surface, the stopper mechanisms 50L, 50R abut against the arms 42L, 42R at positions where the arms 42L, 42R are parallel to the road surface, in other words, at positions where the arms are parallel to the upper surface 12A of the frame 12, thereby preventing the arms 42L, 42R from swinging upward. Therefore, when the automated guided vehicle 10 travels on a flat road surface, each of the pair of arms 42L, 42R abuts against a part of the frame 12 from below, thereby supporting the frame 12.

[0030] The vertical dimension of the frame 12 is smaller than the outer diameter of the rear wheels 14RL, 14RR, which are the drive wheels. As explained above with reference to Figures 1 and 4, the rear wheels 14RL, 14RR are located in a location where the frame 12 is not present. As shown in Figure 5, when the automated guided vehicle 10 travels on a flat road surface, the pair of arms 42L, 42R abut against the stopper mechanisms 50L, 50R. In this state, the upper ends of the rear wheels 14RL, 14RR are at approximately the same height as the upper surface 12A of the frame 12.

[0031] The automated guided vehicle 10 of this embodiment controls its own travel using a control device 60 housed in the housing portion 17 of the frame 12. The control device 60 controls the rotation speed or driving force applied to the pair of rear drive wheels 14RL and 14RR, causing the automated guided vehicle 10 to travel. The control device 60 also creates a difference in the target rotation speed or driving force between the left rear wheel 14RL and the right rear wheel 14RR, thereby varying the actual rotation speed and changing the direction of travel of the automated guided vehicle 10.

[0032] As shown in FIG. 6, the automated guided vehicle 10 is of a so-called route guidance type, which moves along a guide tape (inductor) 62 attached to the road surface. In this embodiment, the guide tape 62 is a magnetic tape, and the automated guided vehicle 10 is equipped with a magnetic sensor (inductor detection sensor) 64 that detects the magnetism of the guide tape 62. As shown in FIG. 1, the automated guided vehicle 10 is provided with magnetic sensors 64 at the center of the vehicle width direction of the front end of the frame 12 (the front-end member that constitutes the main body 16) and at the center of the vehicle width direction of the rear end of the frame 12 (the rear-end member that constitutes the storage section 17). Based on the detection results of the magnetic sensors 64, the control device 60 adjusts the orientation of the automated guided vehicle 10 so that it travels on the guide tape 62.

[0033] The present automated guided vehicle 10 is intended for use in factories and is primarily intended to travel on flat road surfaces. However, even flat surfaces often contain small grooves and recesses. Conventional automated guided vehicles are equipped with suspensions that bias the drive wheels downward, allowing the drive wheels to follow the grooves and recesses. In contrast, the present automated guided vehicle 10 does not have suspensions on the rear wheels 14RL and 14RR, which are the drive wheels. Instead, the rear wheels 14RL and 14RR are supported by arms 42L and 42R to swing freely, allowing them to easily descend relative to the frame 12. Therefore, as shown in FIG. 7 , when the right rear wheel 14RR of the present automated guided vehicle 10 passes through a recess 70 on the road surface, the arm 42R of the right rear wheel 14RR separates from the stopper mechanism 50R, and the right rear wheel 14RR descends to follow the recess 70 and maintain contact with the road surface. Therefore, sufficient driving force can be secured from the right rear wheel 14RR even when passing through the recess 70. As described above, the automated guided vehicle 10 has four wheels, and if one of the wheels is not in contact with the ground, there is a risk that the vehicle's running will be hindered, for example, the vehicle may change direction if one of the drive wheels is not in contact with the ground. However, the automated guided vehicle 10 can achieve stable running.

[0034] Furthermore, in this automated guided vehicle 10, the rear drive wheels 14RL, 14RR are supported by arms 42RL, 42RR so as to be swingable about axes extending in the vehicle width direction, and when traveling on a flat road, the arms 42RL, 42RR abut against a portion of the frame 12, which is the vehicle body, from below to support the frame 12, resulting in a lower floor compared to conventional automated guided vehicles. Furthermore, the height of this automated guided vehicle 10 is approximately the same as the height of the rear drive wheels 14RL, 14RR, resulting in an even lower floor. As described above, even with a low-floor automated guided vehicle 10, the wheels 14FL, 14FR, 14RL, 14RR have high ground contact, enabling stable traveling.

[0035] Furthermore, the automated guided vehicle 10 includes a pair of shafts 40L, 40R that are held by the frame 12 in an orientation extending in the vehicle width direction and that are rotatable about their axes, and each of the pair of arms 42L, 42R is fixed at one end (front end) to the shafts 40L, 40R. This allows the load acting on one end of the arms 42L, 42R to be distributed to the shafts 40L, 40R, improving the durability of the arms 42L, 42R and, ultimately, the durability of the automated guided vehicle 10.

[0036] Furthermore, the automated guided vehicle 10 includes a pair of drive motors 34L, 34R as drive sources, which are provided for each of the pair of rear drive wheels 14RL, 14RR and rotate motor shafts 36 that are coaxially provided with the rear wheels 14RL, 14RR to drive the rear wheels 14RL, 14RR, and each of the pair of arms 42L, 42R is configured to hold the drive motors 34L, 34R and the drive wheels 14RL, 14RR at the other end (rear end). This increases the weight held by the arms 42L, 42R, improving the ability to follow grooves and recesses, i.e., the ground contact of the rear drive wheels 14RL, 14RR, and enabling more stable driving.

[0037] Furthermore, the automated guided vehicle 10 is provided with a magnetic sensor 64 on the front side of the frame 12 as an induction detection sensor for recognizing a guide tape 62 provided on the road surface. The control device 60 causes the automated guided vehicle 10 to travel along the guide tape 62, with the front wheels 14FL, 14FR serving as a pair of auxiliary wheels and the rear wheels 14RL, 14RR serving as a pair of drive wheels. This ensures a certain amount of time between the time of detection by the magnetic sensor 62 and the transmission of a control signal to the drive motors 34L, 34R that drive the rear wheels 14RL, 14RR, thereby ensuring reliable travel along the guide tape 62.

[0038] <Other embodiments> The present invention is not limited to the above-described embodiment, and can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. For example, the following embodiments are also included within the technical scope of the present invention.

[0039] (1) In the above embodiment, the automatic guided vehicle 10 has rear wheels as drive wheels and front wheels as auxiliary wheels, but the automatic guided vehicle disclosed in the present application may have front wheels as drive wheels and rear wheels as auxiliary wheels. (2) The automated guided vehicle 10 of the above embodiment is suitable for a low-floor automated guided vehicle, and the upper ends of the drive wheels and the upper surface of the vehicle body are at approximately the same height, but this is not limited thereto. The automated guided vehicle disclosed in the present application can have a vehicle body of various shapes and configurations depending on the object to be transported. [Explanation of symbols]

[0040] 10...automated guided vehicle, 12...frame (vehicle body), 14FL, 14FR...front wheels (drive wheels), 14RL, 14RR...rear wheels (auxiliary wheels), 34L, 34R...drive motor (drive source), 36...motor shaft, 40L, 40R...shaft, 42L, 42R...arm, 50L, 50R...stopper mechanism, 60...control device, 62...guide tape (inductor), 64...magnetic sensor (inductor detection sensor)

Claims

1. A four-wheeled automated guided vehicle, The car body and a pair of drive wheels disposed on each of the left and right sides of the vehicle body and driven independently of each other; a pair of auxiliary wheels disposed on the left and right sides of the vehicle body either in front of or behind the pair of drive wheels and rotatably held; a pair of arms each extending in a front-rear direction, supported at one end so as to be swingable about an axis extending in a vehicle width direction relative to the vehicle body, and rotatably holding the drive wheel at the other end; a drive source that independently drives each of the pair of drive wheels; a control device that controls the drive source to drive the automated guided vehicle and that can change the direction of travel of the automated guided vehicle by varying the rotation speed of each of the pair of drive wheels; Equipped with When the automated guided vehicle travels on a flat road surface, each of the pair of arms abuts against a part of the vehicle body from below to support the vehicle body, When one of the pair of drive wheels passes over a recess, the arm corresponding to the drive wheel passing through that recess moves away from a part of the vehicle body, and the drive wheel passing through the recess moves down to follow the recess.

2. A four-wheeled automated guided vehicle, The car body and a pair of drive wheels disposed on each of the left and right sides of the vehicle body and driven independently of each other; a pair of auxiliary wheels disposed on the left and right sides of the vehicle body either in front of or behind the pair of drive wheels and rotatably held; a pair of arms each extending in a front-rear direction, supported at one end so as to be swingable about an axis extending in a vehicle width direction relative to the vehicle body, and rotatably holding the drive wheel at the other end; a drive source that independently drives each of the pair of drive wheels; a control device that controls the drive source to drive the automated guided vehicle and that can change the direction of travel of the automated guided vehicle by varying the rotation speed of each of the pair of drive wheels; Equipped with When the automated guided vehicle travels on a flat road surface, each of the pair of arms abuts against a part of the vehicle body from below to support the vehicle body, The vehicle body is provided with a stopper mechanism that abuts against the arm at a position where the arm is parallel to the road surface when the automated guided vehicle is traveling on a flat road surface, thereby preventing the arm from swinging upward.

3. The vehicle body has a height dimension smaller than the outer diameter of the drive wheels, The pair of drive wheels are disposed outside the vehicle body, 3. The automated guided vehicle according to claim 1, wherein the pair of arms abut on the vehicle body at a position where upper ends of the pair of drive wheels are at substantially the same height as an upper surface of the vehicle body.

4. a pair of shafts held by the vehicle body in a position extending in the vehicle width direction and rotatable about an axis; 3. The automated guided vehicle according to claim 1, wherein each of the pair of arms is fixed to the shaft at the one end.

5. the drive source is provided for each of the pair of drive wheels, and includes a pair of drive motors that drive the drive wheels by rotating motor shafts that are coaxially provided with the drive wheels; 3. The automated guided vehicle according to claim 1, wherein each of the pair of arms holds the drive motor and the drive wheel at the other end.

6. a guide detection sensor provided on a road surface on a front side of the vehicle body for recognizing a guide for guiding the automated guided vehicle; the control device causes the automated guided vehicle to travel along the guide, 3. The automated guided vehicle according to claim 1, wherein the pair of auxiliary wheels are front wheels, and the pair of drive wheels are rear wheels.

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