JP2003241831A - Automatic guided vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic guided vehicle, which is capable of shifting to rectilinear traveling at an early stage, by changing the attitude of a car body to be parallel to a guiding line after turning. <P>SOLUTION: The vehicle is provided with a guiding line detection means for detecting a lateral shift between a guiding line and the center line of a car body at the front and rear of the car body, a turning end detecting means for determining that the turning is ended when the lateral shift between the guiding line and the center line of the car body becomes equal at the front and rear of the car body in the autonomous turning motion, and a switching means for switching the traveling of the car body from the autonomous turning motion to the guiding traveling when determined that the turning is ended by the turning end detecting means. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic guided vehicle, and more particularly, to an automatic guided vehicle that travels along a guide line laid on a road surface. [0002] Generally, an unmanned transport system is adopted for the purpose of labor saving and efficiency improvement in transporting a load.
In such an unmanned transport system, conventionally, a guide line is laid on a road surface, and an unmanned transport vehicle is guided along the guide line. As shown in FIG. 3, for example, these automatic guided vehicles are provided with a pair of left and right straddle arms 102 at the front of a vehicle body 101, as shown in a typical reach type forklift. A pair of left and right road wheels 103 rotatably supported on the
1, a drive wheel 104 arranged in the left half, for example.
And a free wheel 105 disposed in, for example, the right half of the vehicle body. [0004] Then, the vehicle 10
A guide sensor 106 as guide line detecting means for detecting guide lines 108x and 108y laid on the running surface at the front part of the vehicle body 101 and the rear part of the vehicle body 101 on the center line C
f and 106r are provided. Further, each straddle arm 102 has a pair of left and right address detections for detecting an address representing a position on the traveling course of the automatic guided vehicle 100 at a position corresponding to the wheel axis FF of the road wheel 103 in a plan view, for example. The means 107 is supported. On the running surface, linear guide lines 108x and 108y are provided for guiding a course, and magnetic bodies 109 for generating address signals are provided in a staggered manner at predetermined intervals, for example. I am. During straight running, the steered wheels 104 are controlled such that the guide line 108x or the guide line 108y matches the center line C of the vehicle body 101 in plan view. That is, for example, one guide wire 108
When the vehicle travels straight along y, deviations (hereinafter referred to as lateral deviations) δf and δr from the center line C of the vehicle body 101 to the guide lines are obtained based on the detection outputs of the front and rear guide sensors 106f and 106r. With each lateral deviation δf, δr
The vehicle body attitude angle (the angle formed by the center line C of the automatic guided vehicle and the guideline 108y) is determined based on the vehicle body angle so that the front and rear lateral deviations δf and δr and the vehicle body attitude angle become as small as possible.
The feedback control (automatic steering correction control) is performed so that the vehicle travels along the guide line 108y while correcting the posture of No. 01. In addition, the guide wire 108
A magnetic body 109 serving as an address index is arranged in a zigzag along the y-axis.
By detecting at 07, the current position can be determined. Note that such control is the same when the vehicle travels straight along the other guide line 108x. In order to carry the load, it is necessary, for example, to turn from one guide line 108y to the other guide line 108x to change the trajectory. Has been conventionally controlled as follows. First, the magnetic body 109 for designating an address provided along one guide line 108y is detected by the address detecting means 107, and turning starts. That is, the address for designating the start of the turn is preset in the control unit of the automatic guided vehicle 100, and the corresponding magnetic body 109 is detected to start the turn. The timing of starting the autonomous turning is when the representative point P representing the position of the vehicle body 101 passes through the turning start point. When the vehicle travels for a distance of?, It is assumed that the vehicle body 101 has passed the turning start point and the vehicle is steered. In this case, since the guide line for turning is not provided, the steering angle of the drive wheel 104 is once fixed so that the vehicle body 101 draws a predetermined circular orbit without performing feedback control as in the case of traveling straight. In this state, the vehicle body 101 is turned. When the vehicle body 101 turns and the lateral deviation δf detected by the front guide sensor 106f becomes equal to or less than a reference set in advance with respect to the guide line 108x, it is determined that the turning has ended. It should be noted that such control is the same when the vehicle turns from the other guide line 108x to the one guide line 108y. [0010] Thereafter, as in the case of straight running, the vehicle body 101 is set so that both the lateral deviations δf, δr and the vehicle body attitude angle are minimized based on the detection outputs of the front and rear guide sensors 106f, 106r. While correcting his posture
Feedback control is performed so that the vehicle travels along the guide line 108x. Further, the drive wheel 10 of the automatic guided vehicle
An encoder 111 is connected to a rotor shaft of a traveling motor 110 that drives the motor 4, and the encoder 111 detects a straight traveling distance from the magnetic body 109 and the like. However, when turning the vehicle body 101 by autonomous control away from the guide lines 108x and 108y, the front guide sensor 106f
In the method of ending the turn when the lateral deviation δf detected at the time is equal to or less than a preset reference value, the tire slips or turns during the turn depending on the inertia force of the vehicle body 101 or the condition of the road surface. In some cases, the skid could not be turned with the correct turning radius. That is, for example, as shown in FIG. 4, at the end of the turn, the turning radius r1 becomes larger than the target radius, and although the guide sensor 106f can detect the guide line laid on the road surface, the guide line 108x Body 10
The angle between the center line C and the center line C, that is, the vehicle body posture angle also increases. Therefore, in this case, after turning, the guide line 108x
There is a problem that the vehicle meanders before recovering straight ahead along the road. The present invention has been proposed based on the above-mentioned conventional circumstances, and provides an automatic guided vehicle in which the posture of a vehicle body 101 becomes parallel to a guide line after turning, so that the vehicle can smoothly transition to straight running. The purpose is to do. [0015] The present invention employs the following means in order to achieve the above object. That is, the present invention relates to an automatic guided vehicle that travels by switching between a guide travel that travels by detecting a guide line laid on a road surface and an autonomous turn that autonomously turns away from the guide line. The carrier has guide line detecting means for detecting a lateral deviation between the guide line and the vehicle center line before and after the vehicle, and a lateral deviation between the guide line and the vehicle center line during the autonomous turning. It is provided with turning end detecting means for judging the end of turning when the front and rear become equal, and switching means for switching the running of the vehicle body from autonomous turning to guide running when the turning end detecting means judges the end of turning. And According to the above construction, when the automatic guided vehicle turns, the lateral deviations δf and δr are obtained based on the detection outputs of the guide sensors provided before and after the vehicle body.
When f and δr become equal to each other, the turning is terminated. At the end of the turning, the vehicle body attitude angle is always parallel to the guide line, so that the vehicle does not meander when traveling straight along the guide line after the turning. Stable straight running is possible. . Embodiments of the present invention will be described below in detail with reference to the drawings. It should be noted that the following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention. FIG. 1 is a schematic functional block diagram of a traveling control unit provided on a body 101 of the automatic guided vehicle according to the present embodiment, and FIG. 2 is a plan view showing a posture of the automatic guided vehicle at the end of turning. It is. The traveling control unit 20 has a course map 21 in which the traveling course, traveling speed, steering angle and the like of the automatic guided vehicle 100 are stored in advance, and an address signal detected by an output of a pair of left and right address detecting means 107 is provided. Is input to the address identification unit 22, and the address at the current position is identified by the address identification unit 22. Further, the straight traveling guide / autonomous turning switching unit 23 determines whether or not to start the autonomous turning based on the identified address and the geographic data of the course map 21. When the autonomous turning is started, the steering angle data at the address from the course map 21 is transferred to the steering calculating unit 24, and the servo amplifier 25 operates the steering motor 26 according to the steering angle data to drive the drive wheel 104 to a predetermined steering angle. Steer. If necessary, the steering angle of the drive wheel 104 is detected, for example, by detecting the rotation of a steering motor 26 with a potentiometer 27 and fed back to the steering calculation unit 24 to correct the excessive or insufficient steering angle. On the other hand, the traveling speed of the automatic guided vehicle 100 is read out from the course map 21 to the traveling speed control unit 28 corresponding to the address identified by the address identification unit 22, and the traveling speed control unit 28 By controlling the traveling motor 110 via the amplifier 29, the traveling speed at the address is controlled.
The traveling speed is controlled by connecting an encoder 111 to a rotor shaft of a traveling motor 110 that drives the drive wheel 104 and feeding back the traveling speed detected by the encoder 111 to the traveling speed control unit 28 to determine whether the traveling speed is excessive or insufficient. Corrected. Further, when turning from one guide line 108y to the other guide line 108x to change the trajectory,
First, the address detection unit 107 detects a specific magnetic body 109 that specifies an address provided along one guide line 108y, and based on the detected address signal, as described above, the address identification unit 22 Identify the address of the location. Subsequently, the straight-ahead guide / autonomous turning switching unit 23 determines whether or not to start the autonomous turning based on the identified current position and the geographic data of the course map 21.
If this determination is the start of turning, autonomous turning is started. That is, the steering calculator 24 outputs a turning signal, controls the steering motor 26 via the servo amplifier 25, and changes the direction of the drive wheel 104 to perform steering. At this time, the steering operation unit 24
Controls the steering angle of the drive wheel 104 so that the vehicle body 101 follows a predetermined arc trajectory.
Turn 1 When the turn starts, the turn end detecting means 31
Guide sensors 106f and 106 serving as guide line detecting means
Check the detection output of r. As the turn progresses, the difference between the lateral deviations δf and δr based on the detected output gradually decreases, and when δf = δr, the vehicle body 101 is parallel to the guide line 108x. Therefore, it is monitored that the lateral deviations δf and δr become equal at predetermined time intervals during turning. During this time, if the lateral deviations δf and δr become equal, the turning end detecting means 31 outputs a turning end signal to the steering operation section 24 and the straight-ahead guide / autonomous turning switching section 23 which is a switching means for switching from autonomous turning to guide traveling. I do. In response to this, the steering calculator 24 controls the steering motor 26 via the servo amplifier 25 to return the steering angle to the straight traveling state, and the automatic guided vehicle 100 finishes turning and shifts to guided traveling. (See FIG. 2). As described above, the turning end detecting means 31
The lateral outputs are obtained by taking the detection outputs of the two front and rear guide sensors 106f and 106r, and when both are equal, it is determined that the turning is completed. Therefore, after turning, the center line C of the vehicle body 101 and the guide line 108x are parallel to each other, and do not meander in a straight traveling along the guide line 108x thereafter. It should be noted that such control is the same when the vehicle turns from the other guide line 108x to the one guide line 108y. Returning to the straight traveling control state, when the automatic guided vehicle 100 stops at the loading position (unloading position), the lateral deviations δf and δr are not zero (provided that δf = δr).
The fork 112 of the automatic guided vehicle 100 shown in FIG. 3 is side-shifted in a direction opposite to the direction in which the lateral deviation occurs. This side shift cancels out the lateral deviations δf and δr, and the automatic guided vehicle 100 may load (unload). Further, in the above-described embodiment, the reach type vehicle is described as an example of the automatic guided vehicle 100, but the present invention is not limited to this. Applicable. As described above, according to the present invention, when the automatic guided vehicle turns, the lateral deviations δf and δr are obtained based on the detection outputs of the guide sensors provided before and after the vehicle body. When the front and rear lateral deviations δf and δr become equal, the turning is terminated. Therefore, at the end of the turning, the vehicle body attitude angle is always parallel to the guide line, and therefore, along the guide line after the turning. Stable straight running can be achieved without meandering in straight running.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic functional block diagram of a traveling control unit of an automatic guided vehicle according to an embodiment of the present invention. FIG. 2 is a plan view showing the posture of the automatic guided vehicle at the end of the turn according to the embodiment of the present invention. FIG. 3 is a schematic plan view showing a traveling state of an automatic guided vehicle in the related art. FIG. 4 is a schematic plan view showing a turning state of the automatic guided vehicle according to the related art. [Description of Signs] 20 Travel control unit 21 Course map 22 Address identification unit 23 Straight running guide / autonomous turning switching unit 24 Steering calculation unit 25 Servo amplifier 26 Steering motor 27 Potentiometer 28 Travel speed control unit 100 Automatic guided vehicle 101 Body 102 Straddle arm 103 Road wheel 104 Drive wheel 105 Free wheel 106f, 106r Guide line detecting means 107 Address detecting means 108x, 108y Guide wire 110 Traveling motor 111 Encoder

Claims (1)

Claims 1. An unmanned transport that travels by switching between a guide travel that travels by detecting a guide line laid on a road surface and an autonomous turn that travels autonomously apart from the guide line. In the vehicle, the automatic guided vehicle is provided with guide line detection means for detecting a lateral deviation amount between the guide line and the vehicle body center line before and after the vehicle body; Turning end detecting means for judging that turning has ended when the amount of deviation is equal between the front and rear of the vehicle body, and switching means for switching the running of the vehicle body from autonomous turning to guide running when the turning end detecting means judges that the turning has ended, Characterized by having