JP2004161405A - Rail-less movable rack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rail-less movable rack capable of preventing a rack body from being excessively tilted when the positional displacement thereof is corrected. <P>SOLUTION: When the positional displacement of this movable rack relative to a guide is detected by a guide sensor (S4), it is determined whether the movable rack is displaced forward or backward (S5), and a control part provides a rotational speed difference between front wheels and rear wheels to correct the positional displacement (S6, S11). When the tilt of the rack body relative to the guide exceeds a specified value θ (S8, S13) before the positional displacement is eliminated (S7, S12) when the positional displacement is corrected, the control part controls a wheel drive mechanism to rotate the front wheels and rear wheels at a same speed (S9). When the correction of the positional displacement is completed (S10), the rotational speed difference is given between the front wheels and the rear wheels until the tilt of the rack body relative to the guide is eliminated to correct the running attitude of the rack (S15 to S22). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a railless moving rack, and more particularly to a railless moving rack in which a rack main body travels on a running path in parallel with a linear guide by correcting positional deviation.
[0002]
[Prior art]
In order to save space inside a warehouse or a factory, a plurality of moving racks are juxtaposed, and these moving racks are moved, for example, electrically so as to approach / separate from each other, and are selectively provided between arbitrary moving racks. A mobile rack system that opens a work passage is used. In particular, for existing warehouses, the use of railless-type movable racks that do not require extensive rail laying work is preferred.
[0003]
In this type of conventional railless moving rack, front wheels and rear wheels are arranged at a distance from each other in a direction orthogonal to a linear guide arranged along a traveling path. When driven by a motor, the rack body runs parallel to the guide. At one end of the rack body, a guide sensor for detecting a displacement of the rack body in a direction orthogonal to the guide is attached. When the sensor detects the displacement, a rotational speed difference between the front wheel and the rear wheel is detected. The position shift is corrected by tilting the rack main body with respect to the guide by giving it (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-262948 [0005]
[Problems to be solved by the invention]
By the way, at the side edges of the front end and the rear end of each rack body, photoelectric entry sensors for detecting that an operator enters a passage formed between adjacent moving racks are attached. However, if a rotational speed difference is continuously applied between the front wheel and the rear wheel of the rack body to correct the positional deviation as described above, the rack main body may not move with respect to the guide until the positional deviation is corrected. There is a possibility that the optical axis of the entry sensor is deviated due to excessive inclination. In this case, the entry sensor malfunctions to detect the entry of the worker, which causes a problem that the movement of the movable rack is unnecessarily stopped or an alarm is issued.
[0006]
The present invention has been made to solve such a problem, and an object of the present invention is to provide a railless moving rack that can prevent the rack main body from being excessively inclined when correcting a positional deviation.
[0007]
[Means for Solving the Problems]
A railless moving rack according to the present invention drives a front wheel and a rear wheel, which are arranged at a distance from each other in a direction orthogonal to a linear guide provided along a traveling path, by a wheel driving mechanism, and The main body is moved in parallel with the guide, and the wheel drive mechanism is controlled so that when the rack main body is displaced in a direction orthogonal to the guide, a rotational speed difference is given between the front and rear wheels to correct the positional deviation. In the railless moving rack, the front wheel and the inclination detecting means for detecting the inclination of the rack main body with respect to the guide when the inclination of the rack main body detected by the inclination detecting means when correcting the positional deviation of the rack main body become a predetermined value or more. A control unit that controls the wheel drive mechanism so that the rear wheels rotate at the same speed.
The control unit rotates the front wheel and the rear wheel at the same speed until the correction of the positional deviation is completed, and thereafter, determines the rotation speed difference between the front wheel and the rear wheel until the inclination of the rack body detected by the inclination detecting means stops. It is preferable to control the wheel drive mechanism to provide.
Further, the inclination detecting means can detect the inclination of the rack body by measuring the traveling distances of the front wheels and the rear wheels with the encoders.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
A railless moving rack according to an embodiment of the present invention will be described with reference to FIG. A pair of fixed racks 13 are arranged on the left and right ends of the traveling path 11, and a guide 14 made of a linear magnetic bar formed along the traveling path 11 is embedded behind the traveling path 11. A plurality of movable racks 15 are arranged between the left and right fixed racks 13 so as to be movable in parallel to the guides 14.
[0009]
Next, the configuration of each moving rack 15 is shown in FIG. The movable rack 15 has a rack body 16, and a front wheel 19 driven by a motor 18 is installed on the right side of a front end 17 of the rack body 16, and similarly, on the right side of a rear end 20 of the rack body 16. A rear wheel 22 driven by a motor 21 is provided. The wheel drive mechanism including the motors 18 and 21 drives the rotation of the front wheel 19 and the rear wheel 22 independently of each other. Encoders 25 and 26 for measuring the traveling distance based on the rotation angle are installed on the axle 23 of the front wheel 19 and the axle 24 of the rear wheel 22 respectively. On the other hand, on the rear end portion 20 of the rack body 16, that is, on the guide 14 side, a guide sensor 27 that detects a positional shift with respect to the guide 14 using magnetism is installed. Further, the motors 18 and 21, the encoders 25 and 26, and the guide sensor 27 are electrically connected to the control unit 28. Note that driven wheels 29 and 30 are provided on the left side of the rack body 16. Further, the motors 18 and 21, the front wheel 19 and the rear wheel 22 may be arranged on the left side of the rack body 16. Further, although not shown, the front edges 17 of the rack body 16 and the side edges of the rear end 20 detect that an operator enters a passage formed between the movable racks 15 adjacent to each other. The photoelectric approach sensors are attached to each of them.
[0010]
Here, a position shift of the rack body 16 in a direction approaching the guide 14 is referred to as a front shift, and a position shift of the rack body 16 in a direction away from the guide 14 is a rear shift.
[0011]
Next, the operation of the railless mobile rack according to this embodiment will be described with reference to the flowchart of FIG. When the traveling of the moving rack 15 is started in step S1, the pulse counts of the encoders 25 and 26 are reset to an initial state in step S2, and the front wheels 19 and the rear wheels 22 of the moving rack 15 are moved to, for example, 10 m / min in step S3. The control unit 28 controls the wheel drive mechanism including the motors 18 and 21 so as to rotate at the same normal speed. In step S4, the guide sensor 27 detects whether or not there is a positional shift with respect to the guide 14 in the moving rack 15 running in this manner.
[0012]
If a position shift is detected in step S4, it is further determined in step S5 whether the position shift is a front shift or a rear shift. Here, as shown in FIG. 4A, when the moving rack 15 is shifted forward with respect to the guide 14, the control unit 28 sets the rear wheel 22 to the normal speed up to that point in step S6. The motor 18 is controlled so that the front wheels 19 rotate at a lower speed than the normal speed, for example, at a low speed of 9 m / min. Thus, as shown in FIG. 4B, the rear end portion 20 of the rack body 16 precedes the front end portion 17 and the rack body 16 is inclined with respect to the guide 14, and the inclination gradually increases as the vehicle travels. .
[0013]
In the following step S7, it is determined whether or not the positional deviation of the rack body 16 has been resolved. If it is determined that the positional deviation is still occurring, the controller 28 proceeds to step S8 where the axles 23 of the front wheel 19 and the rear wheel 22 24, the number of pulses output from the encoders 25 and 26 is compared to calculate the relative difference between the rotation angles and convert the difference into a distance to obtain the difference between the running distance between the front wheel 19 and the rear wheel 22. Then, the inclination of the rack body 16 with respect to the guide 14 is obtained from the difference in the traveling distance and the length of the rack body 16 in the longitudinal direction. Then, it is determined whether or not the inclination is equal to or greater than the predetermined value θ, that is, for example, whether the difference between the traveling distances of the front wheel 19 and the rear wheel 22 of the rack body 16 is equal to or greater than L1.
[0014]
If the difference between the running distances of the front wheel 19 and the rear wheel 22 is less than L1 in step S8, it is determined in step S7 that the positional deviation has been resolved, or it is determined in step S8 that the distance difference has become L1 or more. Steps S6 to S8 are repeated until the front wheel 19 and the rear wheel 22 have different rotational speeds, and the vehicle continues to run. If it is determined in step S8 that the difference in travel distance has become equal to or greater than L1 before it is determined in step S7 that the positional deviation has not been eliminated, the front wheels 19 are moved in step S9 in order to prevent the rack body 16 from tilting too much. And the rear wheels 22 are driven again at the same normal speed. Thus, as shown in FIG. 4C, the rack body 16 travels obliquely with respect to the guide 14, and the guide sensor 27 gradually approaches the guide 14. Then, as shown in FIG. 4D, steps S9 to S10 are repeated until the control unit 28 determines that the displacement of the rack body 16 has been eliminated in step S10.
[0015]
If it is determined that the positional deviation of the rack main body 16 has been eliminated in step S7 before the inclination of the rack main body 16 with respect to the guide 14 is less than the predetermined value θ, the process proceeds to step S14, where the front wheels 19 and the rear wheels 22 are again turned on. Driven at the same normal speed.
[0016]
If the positional deviation determined in step S5 is a rearward deviation, the control unit 28 moves the rear wheel 22 to a speed lower than the normal speed, for example, 9 m / min. The motor 21 is controlled to rotate at a low speed. As a result, the front end portion 17 of the rack body 16 precedes the rear end portion 20 and the rack body 16 is inclined with respect to the guide 14, and this inclination gradually increases as the vehicle travels.
[0017]
In the following step S12, it is determined whether or not the positional shift of the rack body 16 has been eliminated. If it is determined that the positional shift is still present, the guide of the rack body 16 obtained by using the encoders 25 and 26 in step S13. It is determined whether the inclination with respect to 14 is equal to or greater than a predetermined value θ, that is, for example, whether the difference between the traveling distances of the front wheels 19 and the rear wheels 22 of the rack body 16 is equal to or greater than L1.
[0018]
If the difference between the running distances of the front wheel 19 and the rear wheel 22 is less than L1 in step S13, it is determined that the positional deviation has been eliminated in step S12, or it is determined that the distance difference has become L1 or more in step S13. Steps S11 to S13 are repeated until the front wheel 19 and the rear wheel 22 have different rotational speeds, and the vehicle continues to run. If it is determined in step S13 that the difference in travel distance is equal to or greater than L1 before it is determined in step S12 that the positional deviation has not been eliminated, the front wheel 19 and the rear wheel 19 The wheels 22 are driven again at the same normal speed, whereby the rack body 16 runs obliquely with respect to the guides 14, and the guide sensors 27 gradually approach the guides 14. Steps S9 to S10 are repeated until the control unit 28 determines that the positional shift of the rack body 16 has been eliminated in step S10.
[0019]
If it is determined in step S12 that the positional deviation of the rack main body 16 has been resolved before the inclination of the rack main body 16 with respect to the guide 14 is less than the predetermined value θ, the process proceeds to step S14, where the front wheels 19 and the rear wheels 22 are again turned on. Driven at the same normal speed.
[0020]
If it is determined in step S4 that the rack body 16 has not been displaced, if it is determined in step S10 that the displacement has been eliminated, or if the front wheel 19 and the rear wheel 22 of the rack body 16 have the same normal speed in step S14. , The traveling attitude of the movable rack 15 is corrected. First, in step S15, the control unit 28 obtains a difference between traveling distances of the front wheel 19 and the rear wheel 22 based on the number of pulses output from the encoders 25 and 26. If the distance difference is equal to or greater than L2, the number of pulses output from the encoder 25 on the front wheel 19 and the number of pulses output from the encoder 26 on the rear wheel 22 are compared in step S16, and the magnitude of these is determined. judge. Here, L2 is set to a value smaller than L1.
[0021]
When the number of pulses on the front wheel 19 side is larger than the number of pulses on the rear wheel 22 side, that is, when the rack body 16 is inclined with respect to the guide 14 at the front end 17 of the rack body 16 ahead of the rear end 20. In step S17, the control unit 28 controls the motor 18 to rotate the front wheel 19 at a lower speed than the normal speed, for example, at a low speed of 9 m / min, while keeping the rear wheel 22 at the normal speed. Thus, the correction of the traveling posture of the moving rack 15 is started. In step S18, it is determined whether or not the positional deviation with respect to the guide 14 has occurred due to the influence of the correction. If the positional deviation has not occurred, the front wheels 19 are determined in step S19. Steps S17 to S19 are repeated until it is determined that the difference between the traveling distances of the rear wheels 26 is 0 mm. Then, when the difference between the traveling distances becomes 0 mm, it is determined that the movable rack 15 has a normal traveling posture with respect to the guide 14, and the process returns from step S19 to step S4. If a positional deviation with respect to the guide 14 is recognized in step S18, the flow returns to step S5 to correct the positional deviation.
[0022]
On the other hand, if the number of pulses on the rear wheel 22 side is greater than the number of pulses on the front wheel 19 side in step S16, that is, the rear end 17 of the rack body 16 is advanced by L2 or more ahead of the front end 20 and the rack body 16 If it is inclined, the control unit 28 controls the motor 21 in step S20 to rotate the rear wheel 22 at a lower speed than the normal speed, for example, at a low speed of 9 m / min while keeping the front wheel 19 at the normal speed. I do. Thereby, the correction of the running posture of the movable rack 15 is started. In step S21, it is determined whether or not the position of the front wheel 19 is shifted with respect to the guide 14 due to the influence of the correction. Steps S20 to S22 are repeated until it is determined that the difference between the traveling distances of the rear wheels 26 has become 0 mm. When the difference between the traveling distances becomes 0 mm, it is determined that the movable rack 15 has a normal traveling posture with respect to the guide 14, and the process returns from step 22 to step S4. If a positional deviation with respect to the guide 14 is recognized in step S21, the process returns to step S5 to correct the positional deviation.
Further, if the difference between the running distances of the front wheel 19 and the rear wheel 22 is less than L2 in step S15, it is determined that it is not necessary to correct the running posture of the rack body 16, and the process returns to step S3.
[0023]
As described above, when the inclination of the rack body 16 with respect to the guide 14 becomes equal to or larger than the predetermined value θ when correcting the positional deviation, the control unit 28 controls the motors 18 and 21 so that the front wheel 19 and the rear wheel 22 rotate at the same speed. Therefore, the rack main body 16 is prevented from being excessively inclined with respect to the guide 14. Therefore, the optical axis of the entry sensor attached to the front end portion 17 and the side edge portion of the rear end portion 20 of the rack main body 16 is prevented from being deviated, and this sensor is prevented from malfunctioning. A situation in which the movement is stopped or an alarm is issued is avoided.
[0024]
As shown in FIG. 5A, if the rack main body 16 is displaced forward with the front end 17 of the rack main body 16 ahead of the rear end 20, as shown in FIG. By rotating the front wheel 19 at a low speed, for example, 9 m / min. Lower than the normal speed while keeping the wheel 22 at the normal speed, as shown in FIGS. 5B and 5C, once the movable rack 15 travels, Although the amount of front deviation further increases, the running posture of the rack body 16 with respect to the guide 14 gradually changes, and the front deviation is corrected. Before the correction is completed, as shown in FIG. 5D, if the rack main body 16 is inclined by a predetermined value θ or more with respect to the guide 14 when the rear end portion 20 precedes the front end portion 17, the process proceeds to step S9. The front wheels 19 and the rear wheels 22 are driven at the same normal speed so as to prevent the rack body 16 from being tilted too much.
[0025]
Similarly, when the rack main body 16 is displaced rearward in a state where the rear end portion 20 of the rack main body 16 is ahead of the front end portion 17, similarly, in step S11, the front wheels 19 are set to the normal speed while the rear wheels are set to the normal speed. By rotating the motor 22 at a speed lower than the normal speed, for example, at a low speed of 9 m / min, the rearward displacement once increases as the movable rack 15 travels, but the traveling posture of the rack body 16 with respect to the guide 14 gradually changes. Later the gap is corrected. Before the correction is completed, if the rack main body 16 is inclined by a predetermined value θ or more with respect to the guide 14 before the front end portion 17 precedes the rear end portion 20, the process proceeds to step S9 to prevent the rack main body 16 from being excessively inclined. Then, the front wheel 19 and the rear wheel 22 are driven at the same normal speed.
[0026]
In the above-described embodiment, the difference between the traveling distances of the front wheel 19 and the rear wheel 22 is obtained from the number of pulses output from the encoder, and the difference between the traveling distance and the length of the rack body 16 in the longitudinal direction is used for the guide 14. Although the inclination of the rack body 16 has been obtained, the difference in the traveling distance between the front wheel 19 and the rear wheel 22 may be obtained by using a position sensor using a beam such as light or an electromagnetic wave. The inclination of the rack body 16 with respect to the guide 14 may be directly detected using a meter.
The distance difference L1 between step S8 and step S13 can be changed according to the length of the rack body 16 in the longitudinal direction so that the inclination of the rack body with respect to the guide is equal to or more than a predetermined value θ. Can be similarly changed according to the length of the rack body 16 in the longitudinal direction.
[0027]
Further, in the above-described embodiment, since the guide sensor 27 detects a positional deviation in a direction orthogonal to the guide 14, the guide sensor 27 can be installed anywhere in the front, rear, or center of the rack body 16. The guide 14 may be installed on the traveling path 11 in accordance with the installation location of the guide sensor 27.
Also, instead of driving the leading wheel at a normal speed of, for example, 10 m / min with the wheel that is delayed with respect to the traveling direction at a low speed, for example, 9 m / min, lower than the normal speed, It is also possible to drive the lagging wheel at a higher speed than the normal speed, for example, 11 m / min, while keeping the running wheel at the normal speed of, for example, 10 m / min.
[0028]
【The invention's effect】
As described above, according to the present invention, the inclination detecting means for detecting the inclination of the rack main body with respect to the guide and the inclination of the rack main body detected by the inclination detecting means when correcting the positional deviation of the rack main body. A control unit that controls the wheel drive mechanism so that the front wheel and the rear wheel rotate at the same speed when the predetermined value or more is provided. Is prevented from deviating from the optical axis.
[Brief description of the drawings]
FIG. 1 is a plan view showing a railless moving rack according to an embodiment of the present invention.
FIG. 2 is a plan view showing a rack body of the railless moving rack according to the embodiment.
FIG. 3 is a flowchart showing an operation of the railless moving rack according to the embodiment.
FIG. 4 is a diagram showing an aspect at the time of correcting a position shift in the embodiment.
FIG. 5 is a diagram showing another mode at the time of correcting a position shift in the embodiment.
[Explanation of symbols]
Reference Signs List 11 running path, 13 fixed rack, 14 guide, 15 moving rack, 16 rack body, 17 front end, 18, 21 motor, 19 front wheel, 20 rear end, 22 rear wheel, 25, 26 encoder, 27 guide sensor, 28 Control unit.

Claims (3)

The front and rear wheels, which are spaced apart from each other in a direction perpendicular to the linear guides disposed along the traveling path, are driven by a wheel drive mechanism to drive the rack body parallel to the guides. In addition, when the rack body is displaced in a direction perpendicular to the guide, in a railless moving rack that controls a wheel drive mechanism to correct a position shift by giving a rotational speed difference between a front wheel and a rear wheel,
Inclination detection means for detecting the inclination of the rack body with respect to the guide,
A control for controlling a wheel driving mechanism such that when the inclination of the rack body detected by the inclination detecting means is equal to or more than a predetermined value while correcting the positional deviation of the rack body, the front wheel and the rear wheel are rotated at the same speed as each other. And a railless moving rack. The control unit rotates the front wheel and the rear wheel at the same speed until the correction of the positional deviation is completed, and then rotates the rotation speed between the front wheel and the rear wheel until the inclination of the rack body detected by the inclination detecting means is eliminated. The railless moving rack according to claim 1, wherein the wheel drive mechanism is controlled so as to provide a difference. The railless moving rack according to claim 1, wherein the inclination detecting unit includes an encoder that measures a traveling distance of each of a front wheel and a rear wheel.

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