JPH09274519A - Steering controller for simplified unmanned carrier truck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability of steering at the time of turning travel while keeping the driving power of four wheels by outputting a signal for locking the turning axle of a rear side driving unit when the turning travel state of a front side driving unit is detected. SOLUTION: Driving units 10 and 20 provided with a pair of left and right driving wheels 11a, 11b, 12a and 12b to be respectively independently driven are turnably fitted through turning axles 15 and 23 to the front side and rear side of lower face of a trucl frame 2. A steering device is provided with a traveling state detecting means 16 for detecting whether the front side driving unit 10 is set in the turning travel state or not and a lock means 27 for locking the turning axle 25 of the rear side driving unit 20. Then, when the traveling state detecting means 16 detects the turning travel state of the front side driving unit 10, a signal for locking the turning axle 25 of the rear side driving unit 20 is outputted to the lock means 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control device for a simple automatic guided vehicle which maintains the driving force of four wheels and improves the steering stability during turning.

[0002]

2. Description of the Related Art Conventionally, as a simple type unmanned carrier vehicle, a drive unit having a traveling drive mechanism and a steering mechanism is attached to a general manual truck so that the unmanned vehicle travels along a guide belt on a road surface. Those that have been done are known (see, for example, Japanese Utility Model Publication 54004 and Japanese Utility Model Publication 54005).

[0003]

Among such simple type unmanned guided vehicles, in a four-wheel drive system, both front wheels and rear wheels usually have a turning center, and each drive control is independent. It is supposed to be done. At that time, the drive control for the front wheels and the rear wheels is performed based on the output of pickup coils (sensors for capturing the track) attached to the front and rear drive units. Steering
Is done.

However, in the above system, since the turning center of each of the front wheels and the rear wheels is only connected by the bogie frame due to the structure of the bogie, the overrun is caused when the vehicle travels along a curve. Steering is likely to occur, which may cause the vehicle to lose track. This is because when the front wheels are turning, the steering angle of the rear wheels is also in accordance with the curve (in the opposite phase to the front wheels), and the driving force of the rear wheels pushes the rear part of the bogie to the outside of the track. Because it works.

The present invention has been made by paying attention to the above-mentioned problems during turning traveling along a curve, and it is possible to improve the stability of steering during turning traveling while maintaining the driving force of the four wheels. An object of the present invention is to provide a steering control device for a simplified unmanned guided vehicle.

[0006]

In order to achieve the above object, the invention according to claim 1 provides a drive unit having a pair of left and right drive wheels that are independently driven, on the front side of the lower surface of the bogie frame, and In the steering control device of the simplified type automatic guided vehicle, which is mounted so as to be able to turn to the rear via swivel shafts respectively and to be driven unmanned along the guide belt on the road surface, is the front drive unit in the turning traveling state? A traveling state detecting means for detecting whether the front drive unit is in a traveling traveling state by the traveling state detecting means, and a locking means for locking the swing shaft of the rear drive unit; And a control means for outputting to the lock means a signal indicating that the swing shaft of the drive unit should be locked.

In the present invention, the traveling state detecting means detects whether or not the front drive unit (front wheel) is in the traveling traveling state. When the traveling state detection means detects that the front drive unit (front wheel) is in the turning traveling state, the control means sends a signal to the lock means to the effect that the turning shaft of the rear drive unit (rear wheel) should be locked. Output. In response to this signal, the lock means locks the turning shaft of the rear drive unit (rear wheel). That is, when it is detected that the front wheels are turning, such as when the front wheels pass through the entrance of a curve, the turning axis of the rear wheels is immediately locked, and the steering of the rear wheels is forcibly stopped. At this time, the steering angle of the rear wheels is around 0 ° (the same as that when traveling straight ahead). Therefore, when the vehicle is traveling on a curve, the rear wheels are steered in the opposite phase to the front wheels when the turning axis of the rear wheels is not locked as in the conventional case, whereas in the present invention, the rear wheels are fixed at around 0 °. Therefore, the rear part of the bogie is not pushed out of the track by the driving force of the rear wheels, and oversteer does not occur.

According to a second aspect of the invention, in the invention of the first aspect, when the turning shaft of the rear drive unit is locked, at the same time, the pair of left and right drive wheels of the rear drive unit are locked. It is characterized by rotating differentially.

According to the present invention, when the turning axis of the rear wheel is locked, at the same time, the left and right rear wheels are differentially rotated (that is, a rotation difference is given to the outer wheel and the inner wheel of the rear wheel). ). For example, the rotation speed of the inner ring is made lower than that of the outer ring. As a result, the difference between the left and right movements of the rear wheels during turning is absorbed, and smooth turning of the rear wheels becomes possible.

According to a third aspect of the present invention, in the above-described first or second aspect of the present invention, there is provided trajectory detection means that is attached to the rear drive unit and detects the guide band.
The control means detects that the front drive unit is not in a turning traveling state by the traveling state detecting means,
Further, when the guide band is detected by the trajectory detecting means, a signal indicating that the locked state of the turning shaft of the rear drive unit should be released is output to the locking means.

According to the present invention, the guide belt on the road surface is detected by the track detecting means. Since the track detecting means is attached to the rear drive unit, the track detecting means causes the rear drive unit to track. It is detected whether it is above. The control means detects that the front drive unit (front wheel) is not in the turning traveling state (that is, is in the straight traveling state) by the traveling state detecting means, and the guide band is detected by the trajectory detecting means (that is, , The rear drive unit is detected to be on the track), a signal indicating that the locked state of the turning shaft of the rear drive unit (rear wheel) should be released is output to the lock means. In response to this signal, the lock means releases the locked state of the turning shaft of the rear wheel (that is, the turning free state). That is, when the front wheels return to the straight running state by passing through the exit of the curve, and the rear wheels return to the track, the locked state of the turning axis of the rear wheels is immediately released and the rear wheels are in the predetermined normal state. Steering control is performed.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the traveling state detecting means is a steering angle detecting sensor attached to a turning shaft of the front drive unit. When the absolute value of the output is equal to or larger than a predetermined first threshold value, it is determined that the front drive unit is in a turning traveling state.

According to the present invention, since the steering angle detecting sensor is used as the traveling state detecting means, the absolute value of the output (steering angle) of the steering angle detecting sensor is compared with the threshold value to easily turn the vehicle. It is possible to detect whether the vehicle is in a traveling state (the absolute value of the steering angle is greater than or equal to the threshold value) or in a straight traveling state (the absolute value of the steering angle is less than the threshold value). Preferably, the first threshold value is given in advance by an experiment or the like by examining the condition of a curve in which oversteer is likely to occur in the vehicle by using the steering angle of the front wheels as a parameter.

According to a fifth aspect of the present invention, in the above-mentioned fourth aspect of the invention, when the turning shaft of the rear drive unit is locked, at the same time, the rear drive unit is operated in response to the output of the steering angle detection sensor. It is characterized in that the rotation speed of the inner drive wheel of the pair of left and right drive wheels of the side drive unit is reduced.

According to the present invention, when the turning axis of the rear wheel is locked, at the same time, the inner drive wheel (inner wheel) of the pair of left and right rear wheels is output according to the output of the steering angle detection sensor.
Lower the number of rotations. As a result, the difference between the left and right movements of the rear wheels during turning is absorbed in accordance with the steering angle of the front wheels, so that the rear wheels can turn more smoothly.

According to a sixth aspect of the present invention, in the above-mentioned fourth or fifth aspect of the present invention, the invention further comprises a trajectory detecting means which is attached to the rear drive unit and detects the guide band.
When the absolute value of the output of the steering angle detection sensor is equal to or less than a predetermined second threshold value and when the guide band is detected by the trajectory detection means, the control means controls the rear drive unit. A signal indicating that the locked state of the turning shaft should be released is output to the lock means.

According to the present invention, the guide belt on the road surface is detected by the track detecting means. Since the track detecting means is attached to the rear drive unit, the track detecting means moves the rear drive unit to the track. It is detected whether it is above. When the absolute value of the output of the steering angle detection sensor is equal to or less than the threshold value (that is, when it is determined that the front drive unit (front wheel) is in the straight traveling state),
Further, when the guide band is detected by the track detecting means (that is, the rear drive unit is detected to be on the track), the turning state of the rear drive unit (rear wheel) should be unlocked. A signal to the effect is output to the lock means. In response to this signal, the lock means releases the locked state of the turning shaft of the rear wheel (that is, the turning free state). That is, when the front wheels return to the straight running state by passing through the exit of the curve, and the rear wheels return to the track,
Immediately, the locked state of the turning shaft of the rear wheels is released, and predetermined normal steering control is performed for the rear wheels.

[0018]

Therefore, according to the first aspect of the invention, as soon as it is detected that the front drive unit is in the turning traveling state, the turning shaft of the rear drive unit is locked and the steering on the rear wheel side is forced. Since the steering angle of the rear wheels is fixed at around 0 ° even when traveling on a curve,
It is no longer steered in reverse phase with respect to the front wheels. Therefore, the rear portion of the truck is not pushed out of the track by the driving force of the rear wheels, and oversteer does not occur. Therefore, the deviation from the track due to the occurrence of oversteer is eliminated, and the stability of the steering during turning is improved while maintaining the driving force of the four wheels.

According to the invention described in claim 2, in addition to the effect described in claim 1, when the turning shaft of the rear drive unit is locked, the left and right drive wheels thereof are simultaneously rotated differentially. As a result, the left and right movement difference of the rear wheel during turning is absorbed, and smooth turning of the rear wheel becomes possible. Therefore, the entire truck can smoothly turn along the track.

According to the invention of claim 3, in addition to the effect of claim 1 or 2, when the front drive unit returns to the straight traveling state and the rear drive unit returns to the track, Since the locked state of the turning axis of the wheels is released and the normal steering control for the rear wheels is switched, the steering control switching is smoothly performed when returning from the curve running to the straight running,
Steering stability is continuously ensured.

According to the invention described in claim 4, in addition to the effect described in claim 1, since the steering angle detection sensor is used as the traveling state detection means, the structure is simple and inexpensive. In addition, the output of the steering angle detection sensor is compared with a threshold value to determine whether the vehicle is turning, so by changing the threshold value according to the type of truck, the system can be set considering the oversteer characteristics of the truck. Is possible.

According to the invention of claim 5, in addition to the effect of claim 4, when the turning shaft of the rear drive unit is locked, the inner drive wheels are simultaneously output according to the output of the steering angle detection sensor. Since the rotational speed of is reduced, the left-right movement difference of the rear wheels during turning is absorbed in accordance with the steering angle of the front wheels, and a smoother turning of the rear wheels is possible. Therefore, it becomes possible for the entire trolley to turn more smoothly along the track.

According to the invention of claim 6, in addition to the effect of claim 4 or 5, when the front drive unit returns to the straight traveling state and the rear drive unit returns to the track, Since the locked state of the turning axis of the wheels is released and the normal steering control for the rear wheels is switched, the steering control switching is smoothly performed when returning from the curve running to the straight running,
Steering stability is continuously ensured.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are configuration diagrams showing an example of a simplified type automatic guided vehicle according to the present invention, in which FIG. 1A is a side view and FIG. 1B is a view of the vehicle shown in FIG. It is a figure. The basic structure of the simplified automatic guided vehicle shown here is the same as the conventional one.

This simple type unmanned transport vehicle 1 (hereinafter, also simply referred to as a vehicle) is of a four-wheel drive system, and drive units 10 and 20 are attached to the front and rear of the lower surface side of the vehicle frame 2, respectively. Is configured. In addition,
Here, the following description will be given assuming that the traveling direction of the carriage 1 is "front" and the opposite direction is "rear".

For example, front and rear drive units 10, 20
Have almost the same configuration. That is, as shown in FIG. 1 (B), each drive unit 10, 20 has a pair of left and right drive wheels, and these drive wheels are independently driven by dedicated motors. Specifically, the front drive unit (front drive unit) 10 has a pair of left and right drive wheels (front wheels) 11a and 11b, and a casing 12 thereof has drive motors (including a speed reduction mechanism) 13a and 13b. Is provided. The drive wheel 11a on the right side in the traveling direction is driven by the drive motor 13a via the transmission portion 14a, and similarly, the drive wheel 11b on the left side in the traveling direction is the drive motor 13b.
Driven by the transmission unit 14b. That is, the left and right front wheels 11a and 11b are configured to be independently controlled. Similarly, the rear drive unit (rear drive unit) 20 has a pair of left and right drive wheels (rear wheels) 21a and 21b, and the casing 22 thereof has a drive motor (including a speed reduction mechanism) 23a. , 23b
Is provided. The drive wheel 21a on the right side is driven by the drive motor 23a via the transmission portion 24a, and the drive wheel 21b on the left side is driven by the drive motor 23b via the transmission portion 24b. That is, the left and right rear wheels 21
a and 21b are also configured to be independently controlled. In addition, the transmission parts 14a, 14b, 24a,
Reference numeral 24b includes a toothed pulley and a timing belt.

As shown in FIG. 1A, the drive unit 1
Reference numerals 0 and 20 respectively have swivel shafts 15 and 25, and are attached to the bogie frame 2 so that they can swivel with respect to the bogie frame 2 via the swivel shafts 15 and 25. Thereby, as will be described later, the left and right drive wheels 11a, 11b, 21a, 21b of each drive unit 10, 20 are differentially rotated to control the traveling direction of the carriage 1 (steering control). You can The swivel axis 1
The rotation direction of 5, 5 is constantly urged by a predetermined elastic force so that the carriage 1 is driven forward by an elastic member (not shown).

In the present invention, steering angle detection sensors (hereinafter simply referred to as steering angle sensors) 16, 26 are provided on the respective turning shafts 15, 25.
Is attached. The steering angle sensor 16 attached to the turning shaft 15 of the front drive unit 10 detects the steering angle θ _{F of the} front wheels, and the steering angle sensor 26 attached to the turning shaft 25 of the rear drive unit 20 detects the steering angle θ _{R of the} rear wheels. Is detected. The front wheel steering angle sensor 16 constitutes a traveling state detecting means, and by comparing the output (front wheel steering angle θ _F ) of the steering angle sensor 16 with a predetermined threshold value,
It is possible to easily detect whether the front wheels are in the straight traveling state (the absolute value of the steering angle is less than the threshold value) or the turning traveling state (the absolute value of the steering angle is the threshold value or more). As will be described later, the threshold value includes a first threshold value used for condition determination when locking the turning shaft 25 of the rear wheel, and the turning shaft 2 thereof.
There is a second threshold value used for condition determination when releasing the lock state of No. 5 (actually, it is convenient if both threshold values are set to be the same).

Further, in the present invention, especially the rear drive unit 2
A clutch 27 for locking the turning shaft 25 is provided on the turning shaft 25 of 0. The clutch 27 functions as a locking means and is turned on / off by an electric signal. That is, the clutch 27 is set to O
When N, the turning shaft 25 of the rear drive unit 20 (rear wheel) is mechanically locked (fixed), and when the clutch 27 is turned off, the locked state is released and the turning shaft 25 of the rear wheel is free (free to turn). It is supposed to return to the state. As will be described later, the clutch 27 is turned on only when it is detected that the front wheels are turning, and the clutch 2 in the on state is turned on.
7 is turned off when a predetermined condition is satisfied. In addition,
Such a clutch is not provided on the turning shaft 15 of the front drive unit 10, and the turning is always free.

The trolley 1 runs unmanned along a guide band (for example, an optical reflection tape is attached) (not shown) formed on the road surface. Therefore, each drive unit 1
Sensors 18 and 28 (hereinafter referred to as pickup coils) for capturing the induction band (orbit) are attached to the front portions of 0 and 20. Each pickup coil 1
As shown in FIG. 1B, the reference numerals 8 and 28 are each formed by arranging three optical sensors side by side in the lateral direction. When the trolley 1 is traveling on a regular track, these three sensors are located above the width of the guide band on the road surface and can receive the reflected light from the guide band. The track detecting means is constituted by the rear wheel side pickup coil 28 attached to the rear drive unit 20.

The driving control of the carriage 1 is performed by the control device 3 installed on the carriage frame 2. The control device 3 has, for example, a microcomputer built therein, processes input signals from the respective sensors, and drives the drive units 10, 20 (more specifically, the drive wheels 11a, 11b, 21a, 21).
b) and the function of controlling the operation of the clutch 27 on the rear wheel side. Although not shown, the carriage frame 2 includes motors 13a and 13 in the drive units 10 and 20, respectively.
Batteries for supplying electric power to b, 23a, and 23b are attached.

In the trolley 1 configured as described above, the front wheels 11a, 11b and the rear wheels 21a, 21b are detected while detecting the induction band on the road surface by the pickup coils 18, 28.
By controlling the driving of the carriage 1, the cart 1 can be driven unmanned along the guide band. That is, the control device 3
When driving straight, basically, the left and right drive wheels 11a, 11b, 21a, 21b for both the front and rear wheels are driven by being rotated at the same speed. At that time, the trajectory of the carriage 1 is corrected by the pickup coils 18, 28 by the drive units 10, 2, 2.
By detecting the deviation from the 0 induction zone and stopping the rotation of the drive motor of the drive wheel on the opposite side of the deviation direction, the cooperation with the turning mechanism (turnable turning shafts 15 and 25) is achieved. It realizes running along the induction zone. In other words,
Both the front wheels and the rear wheels are picked up by the pickup coils 18 and 28, and the left and right drive wheels 11a and 1
By controlling ON / OFF of 1b, 21a, and 21b,
It realizes running along the track (guide zone) (normal steering control). When the carriage 1 is largely displaced from the induction band and the optical sensors in the center of the pickup coils 18 and 28 are also displaced from the induction band, in order to make a rapid trajectory correction, the drive wheels whose rotation has been stopped should be selected. You may make it apply an electric brake.

Further, even when the vehicle is traveling on a curve, basically, it is possible to realize traveling that follows the curve by performing the above-mentioned normal steering control. In order to prevent the occurrence of oversteer and improve the stability of the steering at that time, special steering control, which will be described in detail below, is performed on the rear wheels during turning. Note that only the normal steering control (ON / OFF control) is performed on the front wheels.

First, the outline of the rear wheel control during turning will be described. As described above, with respect to the front drive unit 10 (front wheel), both the left and right drive wheels 11a and 11b are turned ON / O.
FF control (normal steering control) is performed, but as for the rear drive unit 20 (rear wheel), when the front wheel is detected to be turning, the turning shaft 25 of the rear wheel is immediately locked to steer the rear wheel. Control is performed to forcibly stop and to give a predetermined rotation difference to the outer and inner wheels of the rear wheel. At this time,
The rear wheel side pickup coil 28 is disabled for control purposes.

The rear wheel turning shaft 25 is locked by the turning shaft 2 concerned.
5 is turned on by turning on the clutch 27. Here, the condition for turning on the clutch is, for example, a threshold value to which the absolute value of the output of the steering angle sensor 16 (front wheel steering angle θ _F ) is preset. The value (first threshold value) A or more is set (| θ _F | ≧ A). That is, when the steering angle θ _F (absolute value) of the front wheels becomes equal to or larger than the threshold value A, the front wheels 11a and 11b have started or are continuing the turning motion along a curve in which oversteering may occur. Then, the clutch 27 is turned on and the rear wheel turning shaft 25 is locked. Since the specific value of the threshold varies depending on the structure of the bogie 1, the oversteer characteristic is different. Therefore, in order to prevent oversteer from occurring and to make a natural turning, the turning shaft 25 It is only necessary to verify whether or not it is necessary to perform the rear wheel control during the turn including the lock of, and appropriately determine.

A specific example of the threshold value A is obtained as follows, for example. Consider a case where the truck 1 travels along a curve as shown in FIG. Here, “r” and “φ” in the figure are parameters representing the position of the front wheel (turning center) when the rear wheel (turning center) enters the entrance of the curve, and “r” is the track radius. (M) and “φ” are the positions (deg) of the front wheels. Further, as shown in FIG. 2B, the angle (steering angle) (deg) of the front wheels is “θ” and the wheel base (m) between the front wheels and the rear wheels is “L”. At this time, the following relational expression is established between these parameters. sin (φ / 2) = (L / 2) / r φ / 2 = θ From these two equations, the following equation is obtained. r = L / (2sinθ) From this equation, it is understood that the curve trajectory radius r can be easily obtained by detecting the steering angle θ of the front wheels (the value of the wheelbase L is known in advance). Here, for example, the condition of clutch ON is set when the track radius r is 3 times or less of the wheel base L (that is, r ≦ 3L). Substituting this condition into the above equation and re-expressing it as the condition of the steering angle θ of the front wheels, θ = about 9.6 is obtained from sin θ = 1/6. This value becomes the threshold value A. Therefore, in this case, the condition for clutch ON is the steering angle θ of the front wheels.
_F (absolute value) is about 9.6 ° or more (that is, | θ _F | ≧
9.6).

Further, the rotational difference given to the outer and inner wheels of the rear wheel when the turning shaft 25 of the rear wheel is locked during turning is, for example, as follows. As shown in FIG. 3, the outer wheel side of the rear wheel is given a certain number of rotations as the number of rotations of the front wheel,
As the steering angle θ _{F of the} front wheels increases, a smaller number of rotations is given to the inner wheels of the rear wheels to decelerate. Note that the method of lowering the rotation speed inside the rear wheels in accordance with the steering angle of the front wheels is not limited to the case of continuously decelerating as in the above example,
It may be a case where the speed is gradually reduced.

Further, the rear wheel control during the turning (turning shaft 25
Lock, outer ring / inner ring rotation difference, pickup coil 2
8) is invalidated when it is determined that the front wheels have finished the turning motion and the rear wheels have returned to the track. Specifically, for example, the steering angle θ _{F of the} front wheels is in the vicinity of 0 ° (for example, within ± 5 ° (in this case, the second threshold value is 5 °)), and the pickup on the rear wheel side. At the moment when the coil 28 detects the induction zone (orbit), the locked state of the turning shaft 25 of the rear wheel is released, and the pickup coil 28 on the rear wheel side is switched to the normal steering control as effective control.

FIG. 4 is a flow chart showing the contents of the steering control of the rear wheels, and FIG. 5 is a timing chart showing an example of the control timing at that time. Here, for simplification, the first threshold value and the second threshold value are set to be the same (setting value A).

During straight running, normal steering control is performed on both the front and rear wheels. That is, while detecting the induction band on the road surface with the pickup coils 18 and 28,
O of the drive motors 13a, 13b, 23a, 23b so as to drive the drive units 10, 20 along the guide band.
Drive wheels 11a, 11b, 21 through N / OFF control
The drive of a and 21b is controlled. At this time, the steering angle θ _{F of the} front wheels and the steering angle θ _{R of the} rear wheels are around 0 ° (within ± A) (see FIG. 5).

When the carriage 1 approaches a predetermined curve, the rear wheel control according to the present invention is started. That is, the control device 3
Monitors the steering angle θ _{F of the} front wheels detected by the steering angle sensor 16 of the front wheels (step S1), and determines whether the absolute value is equal to or greater than a predetermined threshold value A (| θ _F | ≧ A). It is determined (step S2).

If the result of this determination is YES, it is determined that the front wheels are making a turning motion, and the clutch 2
7 is turned on to lock the rear wheel turning shaft 25 (step S3), and the rear wheel side pickup coil 28 is disabled for control purposes (step S5).
The number of rotations of the inner wheels of the rear wheels is decelerated according to the steering angle θ _F of the front wheels detected in (see FIG. 3) (step S5), and the process returns to step S1.

That is, as shown in FIG. 5, when it is detected that the front wheels are turning after passing through the curve entrance (|
θ _F | ≧ A), the clutch 27 is immediately turned on.
Then, the turning shaft 25 of the rear wheel is locked. At this time, since the rear wheels have not yet reached the curve entrance, the steering angle θ
_R will be fixed at around 0 ° (the same as when driving straight). Therefore, when traveling around a curve, the rear wheel is steered in the opposite phase with respect to the front wheel when the turning axis of the rear wheel is not locked as in the conventional case (see the chain double-dashed line in FIG. 5). Since it is fixed at around 0 °, the rear portion of the truck 1 is not pushed out of the track by the driving force of the rear wheels, and oversteer does not occur, so that steering stability is achieved. Further, the rear wheels in accordance with the front wheel steering angle theta _F with locking the pivot 25 of the rear wheel so that reduces the rotation speed of the inner ring, the front wheel steering angle theta _F of the left and right rear wheels during turning in accordance with the The movement difference is absorbed, and smooth turning operation is possible for the rear wheels.

If the result of the determination in step S2 is NO, it is further determined whether or not the pickup coil 28 on the rear wheel side has detected the induction zone (track) (step S).
6). If the result of this determination is NO, that is, the steering angle θ _{F of the} front wheels is around 0 ° (| θ _F
<| A), but if the rear wheels have not returned to the track, track correction by the pickup coil 28 does not work for the rear wheels, and normal steering control is not performed in this state. Since it means, the process returns to step S1 and the rear wheel control during the previous turn is repeated.

On the other hand, if the result of the determination in step S6 is YES, that is, the steering angle θ _{F of the} front wheels returns to around 0 ° (| θ _F | <A) which is the same as in the straight running state, and If the wheels have returned to the track, it is determined that the vehicle has finished traveling the curve, and the clutch 27 is immediately turned off to switch the steering control to the normal steering control so that the rear wheel turning shaft 25 is locked. Cancel (Step S
Along with 7), the pickup coil 28 on the rear wheel side is enabled for control (step S8) (see FIG. 5).

Then, the above control is repeated until there is an end command such as a stop command for the carriage 1 (step S9).

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a simplified type automatic guided vehicle according to the present invention.

FIG. 2 is an explanatory diagram of various parameters.

FIG. 3 is a characteristic diagram of rear wheel rotation difference control.

FIG. 4 is a flowchart showing the content of steering control of rear wheels.

5 is a timing diagram showing an example of the control timing of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Simplified automatic guided vehicle 2 ... Truck frame 3 ... Control device (control means) 10, 20 ... Drive units 11a, 11b, 21a, 21b ... Drive wheels 13a, 13b, 23a, 23b ... Drive motors 15, 25 ... Turning axis 16 ... Rudder angle sensor (running state detection means, steering angle detection sensor) 18 ... Pickup coil 26 ... Rudder angle sensor 27 ... Clutch (locking means) 28 ... Pickup coil (trajectory detecting means)

Claims (6)

[Claims] 1. A drive unit (10, 20) comprising a pair of left and right drive wheels (11a, 11b, 21a, 21b) that are independently driven is provided on the lower side of the bogie frame (2) in the front and rear directions. Revolving axis (15, 25)
In a steering control device for a simplified automatic guided vehicle, which is mounted so as to be turnable via a steering wheel so as to run unmanned along a guidance zone on the road surface, it is determined whether the front drive unit (10) is in a turning traveling state. A traveling state detecting means (16) for detecting, a locking means (27) for locking the turning shaft (25) of the rear drive unit (20), and the front drive unit (10) by the traveling state detecting means (16). When it is detected that the vehicle is in a turning traveling state, the turning shaft (25) of the rear drive unit (20)
A control means (3) for outputting a signal to the lock means (27) to lock the vehicle, and a steering control device for a simplified automatic guided vehicle. 2. When the turning shaft (25) of the rear drive unit (20) is locked, at the same time, a pair of left and right drive wheels (21a, 21a, 21a, 21a, 21a) of the rear drive unit (20).
21b) is differentially rotated, and the steering control device for the simplified automatic guided vehicle according to claim 1. 3. A track detecting means (28) attached to the rear drive unit (20) for detecting the guide band, the control means (3) including the running state detecting means (16).
It is detected that the front drive unit (10) is not in the turning traveling state, and the track detecting means (2)
When the guide band is detected by 8), a signal to the effect that the locked state of the turning shaft (25) of the rear drive unit (20) should be released is output to the lock means (27). The steering control device for the simplified automatic guided vehicle according to claim 1 or 2. 4. The running state detection means (16) is a steering angle detection sensor attached to a turning shaft (15) of the front drive unit (10), and an absolute output of the steering angle detection sensor (16) is provided. 2. The stop control device for a simplified automatic guided vehicle according to claim 1, wherein the front drive unit (10) is determined to be in a turning traveling state when the value is equal to or greater than a predetermined first threshold value. 5. When locking the turning shaft (25) of the rear drive unit (20), at the same time, the rear drive unit (20) is responsive to the output of the steering angle detection sensor (16). Left and right pair of drive wheels (21a, 21b)
The stop control device for a simplified automatic guided vehicle according to claim 4, wherein the rotation speed of the inner drive wheel is reduced. 6. A track detection means (28) attached to the rear drive unit (20) for detecting the guide band, the control means (3) including the steering angle detection sensor (16).
When the absolute value of the output of is equal to or less than a predetermined second threshold value and when the guide band is detected by the trajectory detecting means (28), the turning shaft (25) of the rear drive unit (20). 6. The stop control device for a simplified automatic guided vehicle according to claim 4 or 5, wherein a signal indicating that the locked state in (4) is to be released is output to the locking means (27).