JP2007048157A - Travel control system for automated guided carriage cart - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a travel control system that improves the travel control of a guided carriage cart. <P>SOLUTION: The travel control system for an automated guided carriage cart, which comprises drive motors 22 for rotationally driving driving wheels 21 supported in a drive unit 2, encoders 27 for detecting rotational frequencies of the driving wheels 21, and a travel control part 42 for driving the drive motors 22 while examining the rotational frequencies detected by the encoders 27 to control the travel of an automated guided carriage cart 1, is provided with auxiliary wheels 31 rotatably supported in the drive unit 2 so as to be grounded and roll while the guided carriage cart 1 travels actually, and encoders 37 for detecting rotational frequencies of the auxiliary wheels 31. The travel control part 42 reduces the driving force or a target speed of the driving wheel 21 as the difference between the rotational frequency detected by the encoder 27 and the rotational frequency detected by the encoder 37 becomes larger. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a travel control device for an automatic guided vehicle, and more particularly to a travel control device that controls driving of drive wheels provided in the transport cart.

  2. Description of the Related Art Conventionally, a travel control device for an unmanned transport cart that drives a drive wheel supported by a transport cart by a drive motor and controls the travel of the transport cart along a predetermined travel path is known. In such a travel control device, the rotational speed (or circumferential speed) of the drive wheel is usually measured by an encoder directly connected to the drive motor, and the travel speed (or travel speed) during actual travel is based on the number of pulses detected by the encoder. Distance) is calculated and the travel of the transport carriage is controlled.

  By the way, in this travel control device, when the drive wheel is located at the oil adhesion part of the floor, when the drive wheel falls into the uneven part of the floor, or when the forward / backward movement or acceleration / deceleration is switched, etc. In addition, if the driving wheel is idle (so-called slip phenomenon occurs), the above-described traveling speed (or traveling distance) cannot be measured accurately. That is, even if the rotational speed of the driving wheel is increased due to idling, the transport carriage is not actually traveled. Therefore, the calculated travel speed (or travel distance) (calculated value) and the travel speed (or travel distance) during actual travel are calculated. (Actual running value) deviated and the running control accuracy was inferior.

From this point of view, for example, in Patent Document 1, a rotation measuring wheel (auxiliary wheel) that transmits and rotates to a pulse generator to make a differential and ground and rotate when lowered during actual running is separately provided. When the number of running pulses generated by the pulse generator during actual running is compared with the number of running pulses output by the pulse pickup device provided in the running motor, when the difference between the number of running pulses is more than a certain number, There has been proposed a travel control device that determines that a drive wheel has idled and decelerates and stops travel (see Patent Document 1).
JP-A-1-187609

  Indeed, according to the travel control device disclosed in Patent Document 1 described above, the calculated value of the travel speed (or travel distance) and the actual travel value are monitored by monitoring the number of travel pulses of the travel motor and the measurement wheel described above. Control errors due to misalignment can be prevented, and traveling control of the transport carriage can be improved. However, since the transport carriage provided with such a travel control device is usually traveled on a travel route extended to the transport facility, the travel of the transport carriage is stopped each time the drive wheel is idle. The other carriages traveling along the same travel route are prevented from traveling.

  Accordingly, the present invention relates to a travel control device for an automatic guided vehicle, which solves the above-described conventional problems, and automatically controls the travel of the transport cart by returning the gripping force without stopping the idling drive wheels. The object is to propose an improved travel control device.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, according to the first aspect of the present invention, detection is performed by the drive means for rotationally driving the drive wheels supported by the carriage body, the drive wheel rotational speed detection means for detecting the rotational speed of the drive wheels, and the drive wheel rotational speed detection means. A travel control device for driving the automatic guided vehicle by driving the drive means while confirming the number of rotations performed, and capable of rotating on the cart main body. An auxiliary wheel that is supported and rolls while being grounded during actual traveling of the transport carriage, and an auxiliary wheel rotational speed detection means that detects the rotational speed of the auxiliary wheel, and the travel control means is configured to rotate the drive wheel. As the difference between the rotation speed detected by the number detection means and the rotation speed detected by the auxiliary wheel rotation speed detection means increases, the driving force or the target speed of the drive wheel is reduced.

  According to a second aspect of the present invention, a pair of the drive wheels are arranged in the lateral direction of movement and are independently driven to rotate by the drive means, and a pair of the auxiliary wheels are arranged in the lateral direction of movement. As the difference in rotational speed between the driving wheel and the corresponding auxiliary wheel increases, the driving force or the target speed of one driving wheel is reduced.

  According to a third aspect of the present invention, the auxiliary wheel is disposed in the vicinity of the drive wheel and so that the rotation shaft is positioned on a vertical plane passing through the rotation shaft of the drive wheel.

  As effects of the present invention, the following effects can be obtained.

  Since the structure shown in claim 1 is used, the gripping force is automatically returned without stopping the idle driving wheel, and the control error of the traveling speed (or traveling distance) due to the idling of the driving wheel is prevented, It is possible to improve the traveling control of the transport cart.

  Since the structure shown in claim 2 is adopted, the rotational drive of the pair of drive wheels can be independently controlled, so that the accuracy of the traveling control of the transport carriage can be further improved.

  With the configuration shown in claim 3, the accuracy of travel control can be improved by improving the detection accuracy of the rotational speed of the drive wheel and the drive wheel when the transport cart is traveling while turning left and right.

Next, the best mode for carrying out the invention will be described.
FIG. 1 is a bottom view of an automatic guided vehicle provided with a travel control device of the present invention, FIG. 2 is a front view of a drive unit, FIG. 3 is a side view showing the arrangement of drive wheels and auxiliary wheels, and FIG. It is a functional block diagram.
Hereinafter, in FIG. 1, the X direction is the front-rear direction of movement of the transport carriage 1 and the Y direction is the left-right direction of movement. The forward and backward movement direction refers to a direction parallel to the movement direction of the transport carriage 1, and the left and right movement direction refers to a direction perpendicular to the movement direction of the transport carriage 1 in the horizontal plane.

  As shown in FIGS. 1 and 2, the transport carriage 1 according to the present embodiment includes a drive unit 2, a rectangular carriage body 3 and the like connected to the drive unit 2. The drive unit 2 is connected and fixed integrally with the carriage main body 3, but may be configured to be connected via a vertical connection shaft so as to be relatively rotatable with the connection shaft as a rotation center. .

  A pair of swivelable casters (driven wheels) 5, 5 are provided on the lower surface of the cart body 3 at the front and rear positions of the drive unit 2, and the caster 5 is connected to the drive unit 2. -5 is comprised so that it may earth | ground to the running road surface which is not shown in figure. On the upper surface of the carriage main body 3, a placement unit for transported material (not shown) is configured, and the transported product is placed and transported on the placement unit. In addition, a transfer device (not shown) such as a crane or a fork is provided on the upper surface of the transport carriage.

  The drive unit 2 is configured to independently rotate and drive the pair of drive wheels 21 and 21 and the drive wheels 21 and 21 supported by the support frame 20 assembled to the casing so as to be rotationally driven in the lateral direction of movement. The drive motors 22, 22, the power transmission mechanism 23 that transmits the rotational drive from the drive motor 22 to the drive wheels 21, and auxiliary wheels 31, 31 that are rotatably supported below the support frame 20 are configured. Yes. Further, a controller 40 is disposed in the empty space of the support frame 20, and the controller 40 controls the travel of the transport carriage 1 and the transfer of transported items.

  In addition, the structure of the support frame 20 is not specifically limited, What is necessary is just to be comprised as a unit body which fixes the drive wheel 21 grade | etc., Mentioned above to the trolley | bogie main body 3 integrally. However, the drive wheels 21 and the like may be individually attached to the carriage body 3 without using the support frame 20.

  The drive wheels 21 and 21 have a rotation shaft 21 a rotatably supported by the support frame 20, and a power transmission mechanism 23 is formed between the rotation shaft 21 a and the output shaft 22 a of the drive motor 22. Specifically, an output pulley 24 is fixed to the output shaft 22 a of the drive motor 22, and a drive pulley 25 is fixed to the rotation shaft 21 a of the drive wheel 21, and the timing between the output pulley 24 and the drive pulley 25 is set. The belt 26 is wound. With this configuration, the rotational drive from the drive motor 22 is transmitted from the output shaft 22a → the output pulley 24 → the timing belt 26 → the drive pulley 25 → the rotational shaft 21a, and the drive wheel 21 is rotationally driven. . The configuration of the power transmission mechanism 23 may be other mechanical (gear type) or chain belt type.

  The drive motors 22 and 22 are connected to a travel control unit 42 provided in the controller 40 (see FIG. 4), and the travel control unit 42 appropriately switches the driving force to the drive wheels 21 and 21. To be controlled. Specifically, when the transport carriage 1 moves back and forth in the movement direction, the left and right drive wheels 21 and 21 are rotated at the same rotational speed in the same direction. Further, when turning in any of the left and right directions of movement, the driving force of one driving wheel 21 is reduced compared to the driving force of the other driving wheel 21, and the driving of each driving wheel 21 is driven according to the turning angle. The power is changed. In addition, the rotation direction of the one drive wheel 21 and the other drive wheel 21 may be rotated in the opposite direction so that in-situ turning (spin turn) is possible.

  Encoders 27 and 27 as rotation speed detecting means for measuring the rotation speeds of the drive wheels 21 and 21 are connected to the rotation shafts 21a and 21a of the drive wheels 21 and 21, respectively. The encoders 27 and 27 are connected to the travel control unit 42 of the controller 40 (see FIG. 4).

  A pair of auxiliary wheels 31 and 31 are arranged in the vicinity of the inner ring side of the left and right drive wheels 21 and 21, and the rotation shafts 31a and 31a are supported so as to be parallel to the rotation shafts 21a and 21a of the drive wheels 21 and 21, respectively. The frame 20 is rotatably supported. As described above, the number of auxiliary wheels 31 corresponding to the drive wheels 21, that is, one for each drive wheel 21 is provided. However, depending on the configuration of the transport carriage 1, for example, one may be provided for each pair of (two) drive wheels 21 regardless of the number of drive wheels 21.

  The auxiliary wheels 31 and 31 are freely rolled in forward and reverse directions while the roller surface is always in contact with the ground during the actual traveling of the transport carriage 1. The support structure of the auxiliary wheel 31 (rotating shaft 31a) is not particularly limited. For example, the auxiliary wheel 31 is attached to the support frame 20 via a leaf spring member, and the roller surfaces of the auxiliary wheels 31 and 31 are always provided. It is good also as a structure urged | biased in the ground-contact direction (downward). Moreover, it is good also as a structure which can be attached to the support frame 20 so that raising / lowering is possible, and the attachment attitude | position with respect to a grounding surface can be switched so that the auxiliary | assistant wheel 31 may evacuate upwards when the conveyance trolley 1 stops driving | running | working.

  As shown in FIG. 3, the left and right auxiliary wheels 31 and 31 are formed such that the radial length L2 is smaller than the radial length L1 of the drive wheel 21 (L1> L2), and the rotation shaft 31a. The auxiliary line S2 passing through the axial center of 31a and the auxiliary line S1 passing through the axial centers of the rotating shafts 21a and 21a of the left and right drive wheels 21 and 21 are arranged on the same vertical plane P (see FIG. 2). With this configuration, the auxiliary wheels 31 and 31 can be disposed in the vicinity of the inner ring side of the drive wheel 21, and the rotational speed detection accuracy of the drive wheel 21 and the drive wheel 31 can be improved as will be described later. Thus, the accuracy of the traveling control of the transport carriage 1 can be improved.

  Encoders 37 and 37 as rotation speed detecting means for measuring the rotation speed of the auxiliary wheels 31 and 31 are connected to the rotation shafts 31a and 31a of the auxiliary wheels 31 and 31, respectively. The encoders 37 and 37 are connected to the travel control unit 42 of the controller 40 (see FIG. 4).

  As shown in FIGS. 2 and 4, the controller 40 controls the traveling of the transport carriage 1 to travel to a predetermined position and drives the transfer device to control the transfer of the transported object. The controller 40 is connected to the left and right drive motors 22 and 22 and the encoders 27 and 27, and is also connected to a transceiver 41 that transmits and receives data to and from a controller (not shown) on the ground side. The controller 40 receives a transport command via the transceiver 41 and drives the drive motors 22 and 22 to move the transport carriage 1 to a predetermined position. The controller 40 receives the transfer command via the transceiver 41. And a transfer control unit 43 for driving the transfer device. The control units 42 and 43 include a CPU that executes various arithmetic processes and controls, an EEPROM as a nonvolatile memory, a RAM that temporarily stores various data, and the like.

  In the traveling control unit 42, the traveling control pattern of the transport cart 1 is set based on the command input from the transceiver 41. Specifically, the command from the transmitter / receiver 41 includes information on the type, number, location, etc. of the object to be transported, and the travel control unit 42 receives the travel command and transfers the transport cart 1 to the predetermined transport. A travel speed, a travel route, a travel distance, a travel time, and the like (travel control pattern) for traveling to a place are determined. When a start signal is input to the transceiver 41, the rotational drive of the drive motor 22 is controlled according to the determined travel control pattern.

  A pulse signal based on the number of rotations of the drive wheels 21 is input from the encoder 27 every predetermined unit time to the travel control unit 42 during actual travel of the transport carriage 1. Here, the rotation speed of the drive wheel 21 means the rotation speed per certain time (for example, rpm) (hereinafter, the same applies to the rotation speed of the auxiliary wheel 31). In the traveling control unit 42, the pulse signal from the encoder 27 is counted, and the counted number of pulses is compared with the number of pulses at the set speed of the traveling control pattern. When there is a deviation between the two pulse numbers, the driving control unit 42 automatically drives the driving force of the driving motor 22 so that the number of pulses of the drive wheels 21 approximates the number of pulses at the set speed of the driving control pattern. Is controlled. In this way, the travel control unit 42 drives the drive motor 22 while constantly checking the rotation speed of the drive wheels 21 against the number of pulses at the set speed of the travel control pattern, so that the travel speed ( Alternatively, the travel position is controlled.

  However, the travel control device of the transport carriage 1 is not necessarily limited to a configuration in which the travel control unit 42 compares the number of pulses of the drive wheels 21 with the number of pulses at the set speed of the travel control pattern. From the number of pulses of the drive wheels 21 input from the encoder 27, the peripheral speed of the drive wheels 21, the travel distance of the transport carriage 1, and the like may be calculated, and these values may be compared with the corresponding values of the travel control pattern. . In addition, as a factor which the number of pulses of the drive wheel 21 and the number of pulses in the set speed of the travel control pattern deviate, for example, the state of the transport path, the weight of the transported object, and the like can be cited.

  The transport cart 1 collides with an obstacle disposed in the traveling path when the driving wheel 21 is positioned on the oil adhesion portion of the floor surface, when the driving wheel 21 falls on the uneven portion of the floor surface, or In this case, the grip force with the ground contact surface of the drive wheel 21 is reduced, and the drive wheel 21 is idled. When the drive wheel 21 is idling in this way, an error occurs between the travel speed (or travel distance) of the transport carriage 1 calculated from the number of pulses from the drive wheel 21 and the actual travel speed (or travel distance). This causes variations in the accuracy of travel control.

  In the traveling control unit 42 of the present embodiment, when the rotational speed of the driving wheel 21 and the rotational speed of the auxiliary wheel 31 are compared, and the difference N between the rotational speeds (idling amount) increases, the driving force of the driving wheel 21 is increased. The drive motor 22 is controlled so as to be automatically reduced. Specifically, the travel control unit 42 determines whether the transport carriage 1 is actually traveling based on the rotation speed of the auxiliary wheel 31 from the encoder 37 in addition to the pulse signal based on the rotation speed of the drive wheel 21 from the encoder 27. The pulse signal is input and counted every predetermined unit time. In the travel control unit 42, the rotation speeds of the drive wheels 21 and the auxiliary wheels 31 are input as the pulse numbers from the encoders 27 and 37, and the rotation speeds of the drive wheels 21 and the auxiliary wheels 31 are compared as both pulse numbers. Is done.

  In the travel control device of the present embodiment, the driving force of the driving wheel 21 gradually decreases as the rotational speed difference N between the rotational speed (pulse number) of the driving wheel 21 and the rotational speed (pulse number) of the auxiliary wheel 31 increases. Then, when the rotational speed difference N eventually becomes larger than the preset rotational speed difference Ns, control is performed so that the driving force of the drive wheels 21 is rapidly reduced.

  In the travel control unit 42, the drive motor 22 controls the driving force of the drive wheels 21 to gradually decrease as the rotational speed difference N increases until the rotational speed difference N reaches a preset rotational speed difference Ns. Is done. In such a state, for example, if the driving wheel 21 slips when the driving wheel 21 slips to the oil on the floor surface or slips during acceleration / deceleration during traveling, the driving force of the driving wheel 21 is slightly reduced. As a result, the clipping force of the drive wheels 21 is immediately recovered, and the traveling of the transport carriage 1 can be continued.

  On the other hand, when the rotational speed difference N exceeds a preset rotational speed difference Ns, as the rotational speed difference N increases, the driving force of the drive wheels 21 decreases rapidly as compared to the case described above. It is configured. This is because the driving state is reduced even when the driving force of the idling driving wheel 21 is reduced, such as when an object placed in front of the traveling path is pushed and conveyed, or when the driving wheel 21 falls into the uneven portion of the floor surface. If it is not possible to return to, control is performed to further reduce the driving force. In particular, when transporting while pushing an arrangement placed on the travel path, it is possible to perform travel control so as not to destroy the arrangement.

  As described above, in the travel control device, when the rotational speed difference N between the drive wheel 21 and the auxiliary wheel 31 increases, the drive wheel 21, that is, the torque of the drive motor 22 is controlled to switch the drive wheel 21. The gripping force of 21 is automatically restored to improve the traveling performance of the transport carriage 1, and it is possible to prevent a travel speed (or travel distance) control error due to the idling of the drive wheels 21 and to control the travel of the transport carriage. Can be improved. In particular, in such a travel control device, the driving force of the drive wheel 21 is maintained to some extent until the rotational speed difference N becomes a predetermined value or more, and when the rotational speed difference N becomes a predetermined value or more, the driving wheel 21 is driven. By configuring so that the force is further reduced, it is possible to ensure safety during traveling.

The control of the driving force of the driving wheel 21 based on the rotational speed difference N between the driving wheel 21 and the auxiliary wheel 31 is not limited to that described above, and the radial lengths L1 and L2 between the driving wheel 21 and the auxiliary wheel 31, It can be appropriately changed according to the arrangement of the auxiliary wheels 31 with respect to the drive wheels 21, the set travel speed, the travel route, and the like.
In addition, the traveling control unit 42 may perform control so as to switch the torque of the drive motor 22 by reducing the target speed of the drive wheels 21. The target speed of the drive wheel 21 is the speed of the drive wheel 21 set in advance as the above-described travel control pattern. Reducing the target speed means that the travel control unit 42 decreases the set value of the target speed. That is to change. That is, based on the rotational speed difference N between the driving wheel 21 and the auxiliary wheel 31, when the rotational speed difference N increases, the set value of the target speed of the driving wheel 21 is changed in the travel control unit 42, and the driving wheel 21. The speed is controlled to be reduced. Even if it is set as such a structure, there can exist an effect similar to the above-mentioned.

  Further, the transport carriage 1 of the present embodiment is provided with a pair of drive wheels 21 and 21 in the left and right direction of movement, and the drive wheels 21 and 21 are independently driven to rotate by the drive motors 22 and 22, respectively. A pair of auxiliary wheels 31 and 31 are arranged in the vicinity of the drive wheels 21 and 21 in the left-right direction. Therefore, in the traveling control unit 42, the rotation speed (pulse number) of the auxiliary wheels 31 and 31 is compared with the rotation speed (pulse number) of each drive wheel 21 and 21, respectively. That is, the number of rotations (number of pulses) is compared for each of the left and right drive wheels 21 and auxiliary wheels 31. As described above, the traveling control unit 42 can control the driving forces of the pair of drive wheels 21 and 21 arranged in the lateral direction of movement independently of each other, whereby the traveling control accuracy of the transport carriage 1 can be further improved.

  Specifically, when both the left and right drive wheels 21 are idle, the traveling control unit 42 compares the rotation speeds (number of pulses) of the respective drive wheels 21 and 21 and the auxiliary wheels 31 and 31, When the rotational speed difference N increases, the driving force of the driving wheels 21 and 21 is controlled to be reduced. When only one of the left and right drive wheels 21 is idle, the traveling control unit 42 rotates the number of rotations (number of pulses) between the one drive wheel 21 and the auxiliary wheels 31 disposed in the vicinity of the drive wheel 21. ), And when the rotational speed difference N increases, control is performed such that only the driving force of one drive shaft 21 is reduced.

  In particular, in the present embodiment, as described above, the left and right auxiliary wheels 31 and 31 are in the vicinity of the left and right drive shafts 21 and 21, and the auxiliary line S2 passing through the axial centers of the rotation shafts 31a and 31a, Since the auxiliary line S1 passing through the axis of the rotation shafts 21a and 21a of the drive wheels 21 and 21 is positioned on the same vertical plane P (see FIG. 2), the transport carriage 1 is moved in the left-right direction. A shift in the rotational speed between the drive wheel 21 and the drive wheel 31 when traveling while turning can be minimized, and the accuracy of travel control of the transport carriage 1 can be improved.

  In the transport carriage 1 of the present embodiment, the rotational speed of the drive wheel 21 is detected by directly connecting the encoder 27 to the rotary shaft 21a, but the encoder is connected to the output shaft 22a of the drive motor 22. May be connected to detect the rotational speed of the drive motor 22, and the rotational speed of the drive wheel 21 may be detected indirectly.

  In addition, the travel control device of the present embodiment may be either a travel control during high speed travel or a travel control during low speed travel in the transport carriage 1, but preferably as travel control during low speed travel and normal travel Applied.

The bottom view of the automatic guided vehicle provided with the traveling control apparatus of this invention. The front view of a drive unit. The side view showing arrangement of a drive wheel and an auxiliary wheel. The functional block diagram of a traveling control apparatus.

Explanation of symbols

1 Carriage Cart 2 Drive Unit (Car Body)
21 drive wheel 22 drive motor (drive means)
27 Encoder (Drive wheel rotation speed detection means)
31 Auxiliary wheel 37 Encoder (Auxiliary wheel rotation speed detection means)
40 controller 42 travel control unit (travel control means)

Claims (3)

While confirming the number of rotations detected by the driving wheel rotation number detecting means, driving means for rotating the driving wheels supported by the carriage body, driving wheel rotation number detecting means for detecting the rotation number of the driving wheel, A travel control device for an automatic guided vehicle, comprising: a travel control unit that controls the travel of the automatic guided vehicle by driving the drive unit;
An auxiliary wheel that is rotatably supported by the carriage main body and rolls while being grounded during actual traveling of the transport carriage, and an auxiliary wheel rotation speed detection means that detects the rotation speed of the auxiliary wheel,
The travel control means increases the driving force or target speed of the driving wheel as the difference between the rotational speed detected by the driving wheel rotational speed detection means and the rotational speed detected by the auxiliary wheel rotational speed detection means increases. A traveling control device for an automated guided vehicle, characterized by   A pair of the drive wheels are arranged in the left-right direction of movement and are driven to rotate independently by the drive means, a pair of the auxiliary wheels are arranged in the left-right direction of movement, and the travel control means corresponds to one drive wheel. 2. The travel control device for an automatic guided vehicle according to claim 1, wherein the driving force or the target speed of one of the driving wheels is reduced as the difference in the rotational speed from the auxiliary wheel increases.   The auxiliary wheel is disposed near the drive wheel and positioned so that the rotation shaft is on a vertical plane passing through the rotation shaft of the drive wheel. Traveling control device for automated guided vehicles.

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