JP2010146518A - Automatic guided vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic guided vehicle turning to the right and left turning ends with simple constitution to search a guide line. <P>SOLUTION: Stopper members stop turning of a drive unit by contacting each other at the right and left turning ends of a turning unit to a machine base. A microcomputer 75 controls motors 35, 37 when the guide line cannot be detected by a guide line detector 31, to rotate one of right and left driving wheels normally while rotating the other reversely to turn the drive unit. The microcomputer 75 determines arrival at the turning end when at least one of the rotating speeds of the right and left driving wheels during turning of the drive unit is reduced, and rotates the right and left driving wheels in an opposite direction to a rotating direction up to that time to turn the drive unit in an opposite direction to the turning direction up to that time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an automatic guided vehicle.

  Conventionally, an automatic guided vehicle that travels along a guide line is known. Specifically, as shown in FIG. 10, the automated guided vehicle 120 includes a drive unit 130 that independently drives left and right drive wheels 132 by left and right motors 133, and a machine base 140 coupled to the drive unit 130. , By guiding the direction of the drive unit 130 by controlling the difference in rotational speed between the left and right motors 133 so that the center of the guide line detector 134 provided on the drive unit 130 is on the guide line 110 provided on the road surface. Travel along line 110.

In this type of automatic guided vehicle, the guide line detector 134 may not be able to detect the guide line 110 due to disturbances such as road surface unevenness. In this case, the automatic guided vehicle performs an operation for automatically detecting the guide wire 110 (see, for example, Patent Document 1). Specifically, as shown in FIG. 11, one of the left and right drive wheels 132 is rotated forward and the other is rotated backward to turn the drive unit 130 left and right to search for the guide wire 110. At this time, when the drive unit 130 has made a turn to the turnable end with reference to straight running, it is detected and the turning direction is reversed. In order to perform this operation, for example, a rotation angle sensor is mounted at a connection portion between the drive unit 130 and the machine base 140 to detect the rotation angle.
JP-A-9-330122

  However, if a potentiometer S1 (see FIG. 10B) using a variable resistor as a rotation angle sensor is attached to the machine base 140, the sensor height is required to be about 2 cm, for example, and the total height H of the automatic guided vehicle becomes high. In addition, wiring is required and reference point adjustment work is required.

  The present invention has been made under such a background, and an object of the present invention is to provide an automatic guided vehicle capable of searching for a guide line by turning to the left and right turning ends with a simple configuration. is there.

  In the first aspect of the present invention, a drive unit having a left drive wheel motor that rotates the left drive wheel and a right drive wheel motor that rotates the right drive wheel, and a machine base coupled to the drive unit; A guide line detector that is provided in the drive unit and detects a guide line for traveling route guidance laid on the road surface, a pulse generator for the left drive wheel that outputs a pulse accompanying rotation of the left drive wheel, A right drive wheel pulse generator that outputs a pulse associated with the rotation of the right drive wheel, and the guide wire detector detects the guide line and the left drive wheel pulse generator and the right drive wheel pulse generator Travel control means for controlling the left drive wheel motor and the right drive wheel motor while traveling along the guide line while detecting the rotation angle of the drive wheel; The guide wire cannot be detected by the guide wire detector, which is provided on the machine base side and stops at the left and right turning ends of the drive unit with respect to the machine base and stops turning of the drive unit. At times, in order to search for the guide line, the left drive wheel motor and the right drive wheel motor are controlled so that one of the left and right drive wheels is rotated forward and the other is rotated backward to rotate the drive unit. The rotation speed of the left drive wheel and the rotation speed of the right drive wheel when the drive unit is turned by the first guide line search control means and the first guide line search control means When at least one of the two is reduced, it is determined that the drive unit has reached the turning end, and the left and right drive wheels are rotated in the opposite direction. The drive unit controls the motor for wheel motor and the right drive wheel is summarized as further comprising a second induction line searching control means for turning in a direction opposite to the turning direction of the far.

  According to the first aspect of the present invention, the traveling control means detects the guide line with the guide line detector and detects the rotation angles of the left and right drive wheels with the left drive wheel pulse generator and the right drive wheel pulse generator. The left drive wheel motor and the right drive wheel motor are controlled while traveling along the guide line.

  On the other hand, the left drive wheel motor and the right drive wheel motor are controlled by the first guide line search control means in order to search for the guide line when the guide line cannot be detected by the guide line detector. One of the drive wheels is rotated in the forward direction and the other is rotated in the reverse direction to turn the drive unit. When the drive unit is turned by the first guide line search control means by the second guide line search control means, at least one of the rotation speed of the left drive wheel and the rotation speed of the right drive wheel is determined. When one of them decreases, it is determined that the drive unit has reached the turning end, and the left drive wheel motor and the right drive wheel motor are controlled to rotate the left and right drive wheels in the opposite direction. Is swung in the opposite direction to the previous swiveling direction.

  Therefore, without using a dedicated sensor for searching the guide line when the guide line cannot be detected by the guide line detector, the guide line can be searched by turning to the left and right turning ends with a simple configuration. Can do.

  According to a second aspect of the present invention, in the automatic guided vehicle according to the first aspect, the second guide line search control unit is configured to count pulses output from the left drive wheel pulse generator per unit time. When at least one of the number and the count number per unit time of the pulse output from the right drive wheel pulse generator is smaller than a threshold value, it may be determined that the drive unit has reached the turning end.

  According to the present invention, a guide line can be searched by turning to the left and right turning ends with a simple configuration.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the following description, the direction in which the automatic guided vehicle travels is defined as the forward direction, and “rear”, “left”, and “right” are defined based on the forward direction of the automatic guided vehicle.

  As shown in FIGS. 1 and 2, the automatic guided vehicle 10 is configured to be able to load a load on the upper surface of a substantially rectangular parallelepiped machine base 20. The machine base 20 is connected to the drive unit 30 at the substantially center bottom thereof.

  The drive unit 30 includes a frame-like housing 32 having a rectangular shape in plan view, and a pair of left and right drive wheels 50 and 51 are installed in the housing 32. A left drive wheel motor unit 33 and a right drive wheel motor unit 34 are attached to the housing 32. The left drive wheel motor unit 33 includes a left drive wheel motor 35 attached to the housing 32 and a speed reduction unit 36 attached to the output side of the left drive wheel motor 35. The deceleration unit 36 is configured to connect the output shaft of the left drive wheel motor 35 to the axle of the left drive wheel 50. The right drive wheel motor unit 34 is mounted on the output side of the right drive wheel motor 37 and the right drive wheel motor 37 attached to the housing 32 in a state reverse to the left drive wheel motor 35. The reduction gear unit 38 is formed. The deceleration unit 38 is configured to connect the output shaft of the right drive wheel motor 37 to the axle of the right drive wheel 51.

  In the drive unit 30, the left drive wheel motor 35 and the right drive wheel motor 37 are driven, and the left and right drive wheels 50 and 51 are independently driven to rotate through the speed reduction units 36 and 38 by the drive of the motors 35 and 37. .

A pair of left and right driven wheels 25 are provided on the front bottom portion and the rear bottom portion of the machine base 20, respectively.
As shown in FIG. 3, a guide line 60 for guiding the traveling road is laid on the road surface. The drive unit 30 of the automatic guided vehicle 10 is provided with a guide wire detector 31 at a portion facing the guide wire 60. The guide wire detector 31 is disposed near the front of the drive unit 30 (see FIG. 1). The guide wire 60 is detected by the guide wire detector 31. In the present embodiment, a magnetic tape is used for the guide wire 60 and a magnetic sensor is used for the guide wire detector 31.

  The guide wire detector (magnetic sensor) 31 includes a plurality of Hall elements arranged in a direction orthogonal to the direction in which the guide wire (magnetic tape) 60 is laid. The guide wire detector (magnetic sensor) 31 detects the magnetism emitted from the guide wire (magnetic tape) 60 and outputs the detection result to the drive control device mounted inside the drive unit 30 with an analog voltage signal, for example. Is configured to do. When the rotational speed of the left driving wheel 50 is larger than the rotational speed of the right driving wheel 51, the driving unit 30 rotates and turns to the right, and the rotational speed of the right driving wheel 51 is When the rotational speed of the drive wheel 50 becomes larger, the drive unit 30 rotates and turns to the left.

  Further, as shown in FIG. 2, the right drive wheel motor 37 located on the front side of the housing 32 of the drive unit 30 and the left drive wheel motor 35 located on the rear side are located in the central portion of the housing 32. In addition, a bottomed cylindrical boss portion 39 opened upward is provided.

  As shown in FIGS. 2 and 3, a cylindrical connection protrusion 22 that protrudes from the lower surface of the machine base 20 toward the drive unit 30 is inserted into the boss portion 39. The cylindrical connection protrusion 22 has an open bottom surface. Further, the connecting projection 22 is formed integrally with a frame plate 21 that is fastened and fixed to the machine base 20 by a fastening means (not shown).

  Further, a compression coil spring 55 is provided inside the connection protrusion 22 in a state where the connection protrusion 22 is rotatably inserted into the boss portion 39. As shown in FIG. 3, the compression coil spring 55 receives a load from the machine base 20 (see FIG. 2) and urges the drive unit 30 downward, and causes the drive wheels 50 and 51 to have a predetermined wheel load F1 (see FIG. 3). ). The height of the upper surface of the machine base 20 (height from the road surface) is about 20 cm.

  In FIG. 2, stopper materials 23 and 24 are provided at the left and right side end portions of the frame plate 21, and the stopper materials 23 and 24 form a belt plate shape and extend downward. On the other hand, a stopper material 40 projects from the front surface of the outer peripheral surface of the boss portion 39. When the boss portion 39 is rotated to the left and right as the drive unit 30 is rotated to the left and right, the stopper material 40 is also rotated within a range in contact with the stopper materials 23 and 24 provided on the frame plate 21. That is, the rotation of the drive unit 30 is restricted when the stopper member 40 of the drive unit 30 contacts the stopper members 23 and 24 provided on the frame plate 21. Specifically, the angle at which the stopper material 40 on the drive unit 30 side contacts with the stopper materials 23 and 24 on the machine base 20 side is approximately 90 degrees with reference to straight travel.

  In this way, the stopper members 23, 24, 40 are provided on the drive unit 30 side and the machine base 20 side, and the left and right turning ends of the drive unit 30 with respect to the machine base 20 are provided by these stopper materials 23, 24, 40. It is prescribed. At the turning end, the stopper members 23, 24 and 40 come into contact with each other, and the turning of the drive unit 30 with respect to the machine base 20 is stopped.

FIG. 4 is a block diagram showing an electrical configuration.
A left drive wheel motor 35 is connected to the microcomputer 75 constituting the drive control device, and the microcomputer 75 can drive the left drive wheel motor 35 to rotate the left drive wheel 50. Similarly, a right drive wheel motor 37 is connected to the microcomputer 75, and the microcomputer 75 can drive the right drive wheel motor 37 to rotate the right drive wheel 51.

  The left drive wheel motor 35 is provided with a left drive wheel pulse generator (rotary encoder) 70, which is accompanied by rotation of the output shaft of the left drive wheel motor 35, that is, with rotation of the left drive wheel 50. A pulse is output from the left drive wheel pulse generator 70. The pulse signal SG1 of the left drive wheel pulse generator 70 is sent to the microcomputer 75. Similarly, the right drive wheel motor 37 is provided with a right drive wheel pulse generator (rotary encoder) 71, which is accompanied by the rotation of the output shaft of the right drive wheel motor 37, that is, the right drive wheel 51. A pulse is output from the right drive wheel pulse generator 71 with the rotation. The pulse signal SG2 of the right drive wheel pulse generator 71 is sent to the microcomputer 75. The left driving wheel pulse generator 70 outputs, for example, 600 pulses while the left driving wheel 50 makes one rotation. The right drive wheel pulse generator 71 also outputs, for example, 600 pulses while the right drive wheel 51 rotates once.

  The guide wire detector 31 is connected to the microcomputer 75, and the output signal of the guide wire detector 31 is sent to the microcomputer 75. The microcomputer 75 receives a travel command from other equipment such as ground side equipment, loads the load at a station designated by the travel command, carries the load to another station, and executes an operation of placing the load. Yes.

Next, the operation of the automatic guided vehicle 10 configured as described above will be described.
As shown in FIG. 5, the microcomputer 75 as the travel control means detects the guide wire 60 with the guide wire detector 31 and the left and right drive wheels 50 with the left drive wheel pulse generator 70 and the right drive wheel pulse generator 71. , 51 while controlling the left drive wheel motor 35 and the right drive wheel motor 37 while detecting the rotation angle of the left and right wheels 51, the vehicle travels along the guide wire 60.

  Specifically, when the automatic guided vehicle 10 travels, the magnetism generated from the guide wire (magnetic tape) 60 is detected by the guide wire detector (magnetic sensor) 31 so that the center of the guide wire detector 31 is on the guide wire 60. The direction of the drive unit 30 is determined by controlling the speed difference between the two motors 35 and 37.

  In this way, the automatic guided vehicle 10 travels along the guide line 60. At this time, when the guide wire 60 extends in a straight line, for example, the rotational speeds of the drive wheels 50 and 51 are the same, and the automatic guided vehicle 10 travels straight. Further, when the guide wire 60 is bent, a difference occurs in the rotation speed of each drive wheel 50, 51, whereby the direction of the drive unit 30 is changed, and the machine base 20, that is, the automatic guided vehicle 10 is bent. Further, the rotation distance and the rotation speed of the automatic guided vehicle are obtained by detecting the rotation of the output shaft of the motor by the signals from the pulse generators 70 and 71 and obtaining the rotation angle and the rotational speed of the drive wheels 50 and 51 of the automatic guided vehicle. Is calculated, travels at the determined speed, and stops at the determined location.

  On the other hand, when the automated guided vehicle 10 travels along the guide line 60, for example, when passing through a road surface with a step, an external force is applied to the left and right drive wheels 50 and 51 due to some factor, thereby. As shown in FIG. 6, the direction of the drive unit 30 may be changed. Then, when the automatic guided vehicle 10 is shifted laterally from the guide wire 60 and the guide wire 60 cannot be detected by the guide wire detector 31, the automatic guided vehicle 10 stops.

  Since the automatic guided vehicle 10 in the stopped state has not detected the guide line 60, the microcomputer 75 starts the process of searching for the guide line 60 shown in FIG. That is, the drive unit 30 is turned left and right to search for the guide wire 60.

  8 and 9 are time charts for explaining the guide line 60 searching process. 8 and 9, the pulse signal SG1 from the left drive wheel pulse generator 70 and the pulse signal SG2 from the right drive wheel pulse generator 71 are shown. FIG. 8 shows a case where the guide wire 60 can be detected by rotating the drive unit 30 left and right by a predetermined opening degree, and FIG. 9 shows guidance even if the driving unit 30 is rotated left and right by a predetermined opening degree. The case where the line 60 was not detected is shown.

  In FIG. 7, the microcomputer 75 instructs clockwise in step 100. Based on this instruction, the left drive wheel motor 35 is driven to rotate the left drive wheel 50 forward at a constant speed, and the right drive wheel motor 37 is driven to rotate the right drive wheel 51 reversely at a constant speed. As a result, the drive unit 30 turns right.

  In this way, the microcomputer 75 serving as the first guide line search control means detects the guide line 60 when the guide line detector 31 can no longer detect the guide line 60, and the left drive wheel motor 35 and The right drive wheel motor 37 is controlled to rotate one of the left and right drive wheels 50 and 51 in the forward direction and the other in the reverse direction to turn the drive unit 30.

  The microcomputer 75 determines whether or not the guide wire 60 has been detected in step 101 when the drive unit 30 is turning, and proceeds to step 102 if the guide wire 60 is not detected. In step 102, the microcomputer 75 monitors the rotational speeds of the left and right drive wheels 50 and 51, and determines whether or not the rotational speed of at least one of the drive wheels 50 and 51 has decreased. Specifically, it is determined whether the count number per unit time (for example, 50 msec) of the pulses output from the pulse generators 70 and 71 is smaller than a threshold value (for example, 7). When the number of pulses counted per unit time is larger than the threshold value, that is, when the rotational speed of the drive wheels 50 and 51 within a predetermined time is larger than the predetermined value, the microcomputer 75 returns to step 100 and continues clockwise. Instruct.

  The situation in which steps 100 → 101 → 102 → 100 are repeated is the period from t1 to t2 in FIG. 8 and the period from t10 to t11 in FIG. 9. Within this period, the pulse count per unit time is constant. ing.

  Returning to the description of FIG. 7, when the microcomputer 75 detects the guide wire 60 in step 101, the microcomputer 75 shifts to step 107 and shifts to the normal travel mode. Thereby, the microcomputer 75 returns to the state of traveling along the guide wire 60.

  On the other hand, if the microcomputer 75 determines in step 102 that the count number per unit time of the pulses output from the pulse generators 70 and 71 is smaller than the threshold value (the rotational speeds of the drive wheels 50 and 51 within a predetermined time are below a predetermined value). When it is determined that the stopper material 40 on the drive unit 30 side has come into contact with the stopper material 24 on the machine base 20 side, that is, it is determined that the drive unit 30 has reached the right turning end, Transition. 8 and 9, the pulse count per unit time is drastically reduced during the period from t2 to t3 and from t11 to t12. This is because the stopper material 40 on the side of the drive unit 30 and the stopper material 24 on the side of the machine base 20 come into contact with each other, and the further turning of the drive unit 30 is stopped.

  Returning to the description of FIG. 7, the microcomputer 75 instructs counterclockwise in step 103. In response to this instruction, the right drive wheel motor 37 is driven to rotate the right drive wheel 51 forward at a constant speed, and the left drive wheel motor 35 is driven to reversely rotate the left drive wheel 50 at a constant speed. Thus, the left and right drive wheels 50 and 51 are rotated in the opposite direction.

  In other words, the microcomputer 75 as the second guiding line search control means detects the left and right pulse output from the pulse generator 70 for the left drive wheel and the pulse output from the pulse generator 71 for the right drive wheel when the drive unit 30 is turning right. When the rotational speeds of the drive wheels 50 and 51 are calculated and it is detected that the rotational speed of at least one of the drive wheels has decreased below a predetermined value, it is determined that the drive unit 30 has reached the right turning end, and The left drive wheel motor 35 and the right drive wheel motor 37 are controlled to rotate the drive wheels 50 and 51 in the opposite direction so that the drive unit 30 is turned in the direction opposite to the previous turning direction. Turn.

  The microcomputer 75 determines whether or not the guide wire 60 is detected in step 104. If the guide wire 60 is not detected, the microcomputer 75 proceeds to step 105. In step 105, the microcomputer 75 monitors the rotational speeds of the left and right drive wheels 50 and 51, and determines whether or not the rotational speed of at least one of the drive wheels 50 and 51 has decreased. Specifically, it is determined whether the count number per unit time (for example, 50 msec) of the pulses output from the pulse generators 70 and 71 is smaller than a threshold value (for example, 7). When the number of pulses counted per unit time is larger than the threshold value, that is, when the rotational speed of the drive wheels 50 and 51 within a predetermined time is larger than the predetermined value, the microcomputer 75 returns to step 103 and continues counterclockwise. Instruct.

  The situation in which the steps 103 → 104 → 105 → 103 are repeated is the period from t4 to t5 in FIG. 8 and the period from t13 to t14 in FIG. 9, and the pulse count per unit time is substantially constant during this period. Yes.

  Returning to the description of FIG. 7, when the microcomputer 75 detects the guide wire 60 in step 104 (timing t <b> 5 in FIG. 8), the microcomputer 75 shifts to step 107 and shifts to the normal travel mode. Thereby, the microcomputer 75 returns to the state of traveling along the guide wire 60.

  On the other hand, if the count number per unit time of the pulses output from the pulse generators 70 and 71 in step 105 is smaller than the threshold value, the microcomputer 75 reduces the rotational speed of the drive wheels 50 and 51 within a predetermined time below the predetermined value. Then, it is determined that the stopper material 40 on the drive unit 30 side has come into contact with the stopper material 23 on the machine base 20 side, that is, it is determined that the drive unit 30 has reached the left turning end, and the process proceeds to step 106. . As will be described with reference to FIG. 9, the pulse count per unit time is drastically reduced in the period from t14 to t15. This is because the stopper member 40 on the drive unit 30 side and the stopper member 23 on the machine base 20 are in contact with each other.

Returning to the description of FIG. 7, the microcomputer 75 executes an alarm operation or the like, assuming that the guide wire 60 could not be detected in step 106.
As described above, when the guide line 60 is not detected, the drive unit 30 is swung to the right / left to search for the guide line 60. It detects and reverses the turning direction of the drive unit 30. In the case of FIG. 6, the guide wire 60 can be detected by rotating the drive unit 30 counterclockwise, but if the drive unit 30 is rotated clockwise, the guide wire 60 cannot be detected and hits the turning end. Without using a dedicated device for detecting the turning end, it is possible to detect the turning end by detecting the turning end by executing the processing of FIG. 7 and to search the guide wire 60 by rotating the drive unit 30 clockwise / counterclockwise.

  This eliminates the need for a rotation angle detector that detects the turning angle of the drive unit 30, thereby reducing costs. Further, the potentiometer S1 (see FIG. 10B) is not used as the rotation angle sensor, and the overall height of the automatic guided vehicle 10 can be reduced. Furthermore, the reference point adjustment work of the rotation angle detector for notifying the microcomputer 75 of the straight traveling angle becomes unnecessary. Furthermore, since the wiring of the sensor for detecting the turning end does not interfere with the drive unit 30 when the drive unit 30 is turned, the structure can be simplified.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The stopper members 23, 24, and 40 come into contact with the left and right turning ends of the driving unit 30 with respect to the machine base 20 to stop the turning of the driving unit 30, and the guide wire 60 cannot be detected by the microcomputer 75. Sometimes, when the drive unit 30 is turning, if one of the rotational speeds of the drive wheels 50 and 51 calculated from the pulse output from the pulse generators 70 and 71 decreases, it is determined that the turning end has been reached and the opposite direction is reached. Turn to. Thereby, without using a dedicated sensor for searching the guide line 60 when the guide line 60 can no longer be detected by the guide line detector 31, the guide line 60 turns to the left and right turning ends with a simple configuration. Can be searched.

  (2) The microcomputer 75 has at least one of the count number per unit time of the pulse output from the left drive wheel pulse generator 70 and the count number per unit time of the pulse output from the right drive wheel pulse generator 71. If it becomes smaller than the threshold value, it is determined that the drive unit 30 has reached the turning end, so that the turning end can be reliably detected.

The embodiment is not limited to the above, and may be embodied as follows, for example.
Although the example in which the motor itself is provided with a pulse generator like a DC brushless motor has been shown, the pulse generator may be provided in the speed reduction units 36 and 38 in addition to the motors 35 and 37.

The schematic plan view of the automatic guided vehicle in this embodiment. The disassembled model perspective view of an automatic guided vehicle. The partially broken schematic front view of an automatic guided vehicle. The block diagram which shows an electrical structure. The schematic plan view which shows the state which the automatic guided vehicle is drive | working. The schematic plan view which shows the state which the automatic guided vehicle can no longer detect a guide wire. The flowchart for demonstrating an effect | action. The time chart for demonstrating an effect | action. The time chart for demonstrating an effect | action. (A) is a schematic top view explaining a prior art, (b) is a schematic side view explaining a prior art. The schematic plan view explaining a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Automated guided vehicle, 20 ... Machine stand, 23 ... Stopper material, 24 ... Stopper material, 30 ... Drive unit, 31 ... Guide wire detector, 35 ... Motor for left drive wheel, 37 ... Motor for right drive wheel, 40 ... stopper material, 50 ... driving wheel, 51 ... driving wheel, 60 ... induction wire, 70 ... pulse generator for left driving wheel, 71 ... pulse generator for right driving wheel, 75 ... microcomputer.

Claims (2)

A drive unit having a left drive wheel motor for rotating the left drive wheel and a right drive wheel motor for rotating the right drive wheel;
A machine base coupled to the drive unit;
A guide line detector that is provided in the drive unit and detects a guide line for traveling route guidance laid on the road surface;
A pulse generator for the left drive wheel that outputs a pulse accompanying the rotation of the left drive wheel;
A pulse generator for a right drive wheel that outputs a pulse accompanying rotation of the right drive wheel;
The left drive wheel motor and right drive wheel are detected while the left and right drive wheel pulse generators detect rotation angles of the left and right drive wheels while detecting the guide line with the guide line detector. Traveling control means for controlling the motor to travel along the guide line;
A stopper material provided on the drive unit side and the machine base side, and contacting the left and right turning ends of the drive unit with respect to the machine base to stop the turning of the drive unit;
When the guide line cannot be detected by the guide line detector, the left drive wheel motor and the right drive wheel motor are controlled to rotate one of the left and right drive wheels in order to search for the guide line. And a first guiding line search control means for rotating the drive unit by rotating the other in the reverse direction,
When the drive unit is turned by the first guide line search control means, if at least one of the rotation speed of the left drive wheel and the rotation speed of the right drive wheel decreases, the drive unit The left driving wheel motor and the right driving wheel motor are controlled so that the left and right driving wheels are rotated in the opposite direction by determining that the turning end has been reached, and the driving unit is controlled so far. Second guiding line search control means for turning in a direction opposite to the turning direction;
An automatic guided vehicle comprising:   The second guide line search control means includes a count number per unit time of a pulse output from the left drive wheel pulse generator and a count number per unit time of a pulse output from the right drive wheel pulse generator. 2. The automatic guided vehicle according to claim 1, wherein when at least one of the two is smaller than a threshold value, it is determined that the drive unit has reached the turning end.

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