JPH0296808A - Spin turn method of unmanned carrier able to teach termination position - Google Patents

Abstract

PURPOSE:To speedily attain spin turn and to always stop at an accurate position by previously providing a moving quantity to a termination position for a storage device as a constant and terminating spin turn by means of the constant. CONSTITUTION:In a controller, the moving quantity to the termination position of spin turn, namely, the number of pulses in a travel pulse motor is previously taught and set in the storage device. A user optionally sets the additional number of pulses as the system constant, he can terminate spin turn at the accurate position with setting a turning angle to be always 90 degrees. When a front wheel 29 is rotated, and furthermore the front wheel 29 is rotated by driving and turning the pulse motor at the number of pulses obtained by multiplying the number of pulses of the system constant which has been taught and set in a RAM by four times, a carrier can be stopped at the termination position of spin turn, namely, at a position parallel to a guidance line 49 which is beyond a corner. Thus, spin turn can speedily be performed and the carrier can always reach the accurate position.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention: Field of the Invention The present invention relates to a spin-turn method for an automatic guided vehicle in which an end position can be taught.

B. Summary of the invention In a spin-turn method in which an automatic guided vehicle is turned around a certain point, if the end position is determined by detecting a guide line, etc., it is possible to quickly execute the detection and judgment process. However, in the present invention, since the amount of movement to the end position can be taught and set in the storage device in advance, running can be resumed immediately after reaching the end position. Further, by finely adjusting the amount of movement of the storage device depending on the road surface condition, it is possible to always reach the correct end position.

C. Prior Art Conventionally, forklifts have been widely used as cargo handling vehicles, and in recent years, unmanned forklifts that carry out cargo handling operations unmanned have also been developed.

However, a forklift has a complicated structure such as a mast that raises and lowers the fork and a tilt mechanism that tilts the mast, and the fork makes complicated movements during cargo handling operations. Therefore, forklifts are generally expensive, and moreover, unmanned forklifts require complicated control devices, resulting in extremely high manufacturing costs for unmanned forklifts.

On the other hand, so-called low-lift transport vehicles have also been developed that are suitable for handling pallets and the like on the floor level, although they do not have the variety of tasks that forklifts do as cargo handling vehicles. This is equipped with a loading fork having a limited lifting height of about 100 to 200 degrees, and uses the fork to slightly lift a pallet or the like that is on the floor level and conveys it on the floor as it is. This low-lift transport vehicle does not require a mast for raising and lowering the forks or its tilt mechanism, which is required in a forklift, and has the advantage that it has a simple structure, can be made smaller, and can be manufactured at low cost. There is.

D. The problem to be solved by the invention Until now, there has been no unmanned version of the above-mentioned low-lift automatic guided vehicle, but the important points in making it unmanned are:
The key is to be able to travel accurately and quickly along a pre-planned course.

The problem here is control when changing directions rather than when traveling on a straight course. For example, when a guide wire is buried in the road surface and the vehicle travels while detecting the magnetic field generated by the guide wire, a method of spin-turning at curved corners is adopted. In this spin turn, the driving wheel is temporarily stopped to interrupt the visiting travel, the steering wheel is completely cut, and then the driving wheel is driven to rotate to change direction around a certain point.

However, in the past, as a means of detecting the end position of a spin turn, the magnetic field created by a guiding wire in front of the bend was detected, and the end position of the spin turn was determined when the magnetic field was parallel to this guiding wire. For this reason, the execution speed of processing such as detection and judgment was slow, and it was not possible to quickly change direction. Furthermore, in the method of detecting a magnetic field, the parallelism to the guide wire is not necessarily sufficient, and the wire may meander afterward.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spin-turn method for an automatic guided vehicle in which the end position of a spin-turn can be taught in advance.

E. Means and action for solving the problem A constant is taught and set in the memory device as the amount of movement to the end position of the spin turn in advance, and when the traveling distance of the driving wheel matches this constant, the driving wheel is stopped. Then, the spin turn is completed, so the spin turn can be executed more quickly than when the end position of the spin turn is determined by detecting the guide line or the like. Furthermore, by finely adjusting the constants taught to the memory device, it is possible to always reach the correct end position even if the road surface conditions vary.

Embodiment F An embodiment of the present invention will be described in detail below with reference to the mouth surface.

FIG. 3 is a partially transparent perspective view of a low-lift automatic guided vehicle used in an embodiment of the present invention, and FIG. 4 is a side view showing the lift l-i structure of the fork.

This low-lift type automatic guided vehicle has a fork 12 for carrying 84 objects connected to the rear part of a main body frame 11 so as to be able to move up and down. This fork 12 consists of two fork parts 13 that extend horizontally backward on which cargo is placed, and a mounting part 14 that stands up vertically from the cut end of this fork part 13. As shown in the figure, this is connected to the main body frame 11 by a mounting portion 14. That is, the upper part of the mounting part 14 of the fork 12 is pivotally connected to a pair of left and right support links 15 which are pivotally connected to the upper part of the main body frame 11, and is also pivotally connected to a bracket 16 provided on the lower surface of the main body frame 11. A pair of left and right drive link Fs are pivotally attached to the lower part of the fork 12 by a pin 18, and the fork 12 can be moved up and down on the main body frame 11 by the four-bar link mechanism constructed thereby.

Further, between the support link 15 and the drive link 17, a pair of left and right hydraulic cylinders 19 for raising and lowering the fork are located facing in the vertical direction, and the cylinders and rods are used to attach the main body frame 11 and the fork 12, respectively. The brackets 1-20 and 21 are connected to the brackets 1-20 and 21, respectively, which project from the portions 14. Therefore, when the hydraulic cylinder 19 is driven to extend, the fork 12 rises relative to the main body frame 11, while when it is shortened, the fork 12 descends relative to the main body frame 11, as shown in FIG. Here, the fork 12 is maintained parallel to each other at its ascending and descending ends by the action of the link mechanism described above.

On the other hand, a rear @ 22 is provided on the lower surface of the tip (rear end) of the fork portion 13, respectively.

These rear wheels 22 are driven wheels rotatably supported around a horizontal axis perpendicular to the longitudinal direction of the fork portion 13, and one pair is provided for each fork portion 13. The pair of rear wheels 22 are pivotally supported by a connecting plate 23, and a driven link 24 pivotally attached to the connecting plate 23 is pivotally attached to the lower surface of the fork part 3 by a pin 25. It is attached to 13. Further, a pull rod 27 is pivotally connected to the driven link 24 by a pin 26 located below the pin 25.
The other end is pivotally connected to the drive link 17 by a pin 28 located above the pin 18.

When the fork 12 is in the lowered position as shown in FIG. 2, the driven link 24 is in a collapsed state, and the rear wheel 22 supports the tip of the fork portion 13 in the lowered position. On the other hand, the fork 1 is
2 is raised to the raised position, the drive link 17 rotates counterclockwise as shown in FIG.
4 rotates clockwise and stands diagonally as shown by the imaginary line in FIG. As a result, the distance between the rear wheel 22 and the upper surface of the fork section 13 increases, and the rear wheel 22 becomes able to support the tip of the fork section 13 in the raised position. That is, the driven link 24 constitutes a mechanism for raising and lowering the fork part 13 relative to the rear wheel 22, so that the tip of the fork part 13 can be supported by the rear wheel 22 even when the fork wheel 2 is in either the raised or lowered position. ing.

As shown in FIG. 1, a front wheel 29, which is a steering drive wheel, is disposed on the main body frame 11. That is, the steering shaft 30 is movable around a vertical axis on the main body frame 11.
is supported, and a lower ζζ support base 31 of the steering shaft 30 is attached to the steering shaft 30 so as to be unrotatable around the axis and movable in the axial direction.
A front wheel 29 is rotatably supported around a horizontal axis at the lower part of the vehicle. Further, a spring receiver 32 is provided protruding from the steering shaft 30, and a compression coil spring 33 is interposed between the spring receiver 32 and the support base 31, so that the support base 31 is urged downward. This allows the front wheels 29 to be pressed against the running floor.

A travel drive motor 34 and its drive gear 35 are mounted on the support base 31, and are rotated in forward and reverse directions by the operation of the drive motor 34 of the front wheels 29. On the other hand, a gear 36 is fixed to the steering shaft 30, and a drive pinion 38 of a steering motor 37 supported by the main body frame 11 meshes with this gear 36. When the steering motor 37 is operated, the drive pinion 38° The front wheels 29 can be steered by rotating the steering shaft 30 via the gear 36 ◇HO auxiliary wheels 39 having caster functions are attached to the main body frame 11 on both the left and right sides, sandwiching the front wheels 29. installed.

Furthermore, the body frame 11 is equipped with the aforementioned hydraulic cylinder 19.
An electro-hydraulic power unit 40 is mounted to operate the motor. The fork 12 also includes this hydraulic power unit 40 and the aforementioned drive motor 34. A battery 41 that drives the steering motor 37 is mounted, and the weight of the battery 41 is used to shorten the time required for the fork 12 to lower when there is no load.

Further, a bracket 42 is attached to the support base 31 that supports the front wheel 29 at a position in front of the front portion 29. The forward movement sensors 43 are fixed at symmetrical positions with respect to a29. On the other hand, the tips (rear ends) of the two fork parts 13 of the fork 12
Reverse movement sensors 44 are fixed to positions behind the rear wheels 22 of the vehicle.

These sensors 43, 44 detect guide wires laid in advance on the running floor surface.
A control device (not shown) that controls the steering motor 37 in accordance with the output signal No. 4 is mounted on the main body frame 11. In FIG. 1, 45 is an operator console panel for operating the control device, 46 is a power key switch, and 47 is a mode changeover switch.

These sensors 43 and 44 have optical and magnetic types depending on the guide wire laid on the running floor surface.

Various types such as electromagnetic type can be used.

For example, in addition to using pickup coils as the sensors 43 and 44, a low frequency current is passed through a guide wire buried under the running floor surface, and the sensors 43 and 44 are positioned within the magnetic field formed by this current. A method using an induced voltage is preferably used.

That is, as shown in FIG. 3, when a low frequency current is passed through the guide wire 49 buried in the running floor surface 48, a magnetic field 50 is formed around the outer periphery of the guide wire 49 and concentrically therewith. If the pickup coils, which are the sensors 43 and 44, are located within this magnetic field 50, an induced voltage will be generated there.

Now guide to the center of the left and right sensors 43 and 44! @49
If there is, the same induced voltage will be generated in the left and right sensors 43, 44, but if this deviates, a potential difference will occur in the left and right sensors 43, 44.

Therefore, the steering motor 37 is operated according to this potential difference to move the front portion 29 19! By steering, the conveyance vehicle can travel along the guide line 49.

In order to cause the low-lift automatic guided vehicle having the above configuration to perform a spin turn, follow the procedure #A shown in FIGS. 1 and 2. That is, as shown in FIG.
Guided by a low-lift automated guided vehicle that travels along! t1
449, the front part of this conveyance vehicle went too far around the corner, and as shown by the dashed line in the figure,
When a22 reaches the turning angle, the rotation of the front wheels 29, which are the driving wheels, is stopped, and the guided travel along the guide line 49 is interrupted. In this embodiment, since the center of the left and right rear wheels 22, which are driven wheels, is the center, the spin turn is stopped at the position indicated by the dashed line in FIG. 1, but the center of the spin turn is not limited to this. It is better to stop so that they match. Next, after turning the front part 29, which is the steered wheel, by 90 degrees, the pulse motor used as the driving drive motor 34 is energized to drive and rotate the driving f1h wheel as well as the t7i7 wheel 29, as shown in the solid line in FIG. The g-lift type automatic guided vehicle is turned around the center of the rear wheels 22 as shown in FIG. Here, in the control device (not shown), the amount of movement to the spin turn end position is previously taught and set in a storage device. That is, as shown in FIG. 1, the bending angle of the guide wire 49 is 9
If it is 0 degrees, the automatic guided vehicle also needs to turn 90 degrees around the center of the rear wheels 22 by spin turn.

For this purpose, the front wheel 29, which is a WAmJ wheel, needs to run in a quarter arc with the radius of the front and rear wheel bases, and the rotational speed of the front wheel 29 required for this is
It can be found from the radius of Furthermore, the number of pulses of the pulse motor used as a driving drive motor for rotating the front wheels 29 is also determined. Therefore, the number of pulses is taught and set in the ROM (Road Only Armory) of the storage device. Once this ROM is set, it cannot be changed, so it is desirable to select and install the ROM according to the user's specifications at the shipping stage, depending on the bending angle of the guide cotton 49. However, it is still possible that the spin turn end position may deviate from the predetermined spin turn end position depending on whether there is a load on the automatic guided vehicle or due to approximately concave resistance. Therefore, in order to make fine adjustments according to such changes in the situation, we use RAM (Random access me + memory) of the storage device.
) allows the user to optionally set an additional number of pulses as a system constant. In other words, R.O.
If the turning angle becomes smaller or larger than 90 degrees when running with the constant number of pulses stored in M, the system constant pulse number is adjusted accordingly and the turning angle is always kept at 90 degrees. This allows the player to finish the spin turn in the correct position.

Therefore, the af! Pulse smoke (travel drive motor 3) according to the set number of pulses
4), rotate the front wheel 29, and continue to R.
The number of pulses, which is the system constant taught to AM, is 4@
When the pulse motor is driven to rotate according to the number of pulses determined, and the front wheel 29 is rotated, it can be stopped at the end position of the spin turn. Incidentally, the end position of the spin turn refers to a state in which the spin turn is parallel to the guide line 49 ahead of the turning angle.

Thereafter, the front wheels 29, which are the steered wheels, are turned 90 degrees to the original position, and guided travel along the guide line 49 is resumed.

The angle of direction change by spin turn is 90 degrees (but is not limited to 90 degrees).Also, it is not limited to those that use ROM and RAM as storage devices.
Either one may be omitted. Further, in the above embodiment, the front wheels 29 are m-driving wheels and also serve as steering wheels, but the spin turn of the present invention may also be implemented with other configurations. For example, if the front wheels 51 are steering wheels and the rear wheels 52 and 53 are driving wheels as shown in FIG. 6 ta+, then f
After cutting f11 wheel 51 90 degrees, rear wheel 52.53
When rotated in the opposite direction, the t&wheels 52, 5. You can perform a spin turn in which you revolve around the center of (.

Further, as shown in FIG. 6(b), a front wheel 54, a rear wheel 55.
When both 58 are steering wheels and driving wheels, it is preferable that both the front wheels 54 and the rear wheels 55 and 56 are turned as shown in the figure and driven and rotated in the same direction. Furthermore, as shown in FIG. 6(c), Wl! is placed in the center. I! lI import 57
, 5B are arranged, and steering wheels 59 and 6 are arranged at the front and rear, respectively.
0 is arranged, it is preferable to turn the steering wheel 59.60 by 90 degrees and then rotate the drive wheel 59.60 in the reverse direction.

G. Effects of the Invention As described above in detail based on the embodiments, the present invention teaches and sets the movement 11IJiL to the end position in advance as a constant in the storage device, and ends the spin turn using this constant. Therefore, a spin turn can be executed more quickly than in the case of detecting a guiding wire. Moreover,
By fine-tuning the constants of the storage device, it is possible to always stop at the correct position.

[Brief explanation of drawings]

Figures 1 to 5 show an embodiment of the present invention, Figure 1 is a plan view showing how a spin turn is executed, Figure 2 is a flow chart of the spin turn method, and Figure 3 is a low lift type. FIG. 4 is a side view of the low-lift automatic guided vehicle; FIG. 5 is an explanatory diagram showing the magnetic field created by the guide wire and the arrangement of sensors; FIG. 6(a) (bl
(cl is a steering wheel showing an example of other arrangement of KI & driving wheels. This is an explanatory diagram. In the diagram, 11 is the main body frame, 12 is a fork, 19 is a hydraulic cylinder, 22 is a rear wheel, and 43 is a forward movement sensor. , 44 is a reversing sensor, and 49 is a guide wire.

Claims (1)

[Claims] In a spin turn method in which the automatic guided vehicle changes direction around a certain point by stopping the driving wheels of the automatic guided vehicle, turning the steering wheels to a standstill, and then driving and rotating the driving wheels, the storage device 1. A spin-turn method for an automatic guided vehicle, characterized in that the drive wheel is stopped and the spin-turn is completed when the amount of movement to the end position matches a constant previously taught as the amount of movement to the end position.