JPH01187609A - Travel control method for unmanned truck - Google Patents

Abstract

PURPOSE:To prevent run-away by comparing number of traveling pulses generated at the time of actual travel by a pulse generator and the number of the traveling pulses outputted by a pulse pickup device installed on a traveling motor, and judging that abnormality occurs and reducing the speed and stopping the travel when a difference between both the numbers of the traveling pulses becomes larger than a definite value. CONSTITUTION:On an unmanned truck, a lift type measuring wheel 14 to transmit rotation to a rotary encoder 20 and operate it is installed so as to touch the ground rotate when it is moved down at the time of the travel, and in addition, a pulse pickup is installed in the rotary encoder 20 so as to be capable of detecting the rotation of the traveling motor, and at the time of the actual travel, the measuring wheel 14 is moved down and is made to touch the ground. Then, the number of the traveling pulses the rotary encoder 20 generates and the number of the traveling pulses the pulse pickup detects are compared, and the occurrence of the abnormality is detected by that the difference of both the numbers of the traveling pulses comes larger than a definite value, and immediately the truck is decelerated and the travel is stopped. Thus, the run-away due to the discrepancy of the position information of the lift type measuring wheel 14 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for driving an automatic guided vehicle to prevent runaway and the like and to control the vehicle to travel safely.

The running speed of an automatic guided vehicle loaded with conventional technical parts, etc., changes constantly due to changes in load, changes in road surface conditions, and the characteristics of the running motor, so it is necessary to compensate for these speed changes. For this purpose, automatic guided vehicles equipped with speed control means have been developed (Japanese Patent Laid-Open No. 62-180006 and
2-160008, etc.), and as a conventional speed control method for automatic guided vehicles, for example, the rotation of the traveling motor is detected by a pulse pickup device, and
Either correct the traveling speed according to the difference between the number of pulse signals counted within 00 m, s (milliseconds) and the number of traveling pulse signals at a pre-registered reference speed, or A measurement wheel such as a contact-type tachometer 1111J device as described in the above issue is installed separately from the running wheels, and the speed or distance traveled is determined from the pulse signal generated and the speed is controlled based on the error from the reference speed. I was doing it.

Problems to be Solved by the Invention However, in the case of the former method of detecting the rotation of the travel motor using a pulse pickup device among the conventional speed control methods for automatic guided vehicles described above, it is difficult to When the slip rate of the drive wheels changes due to changes in load, etc., and the drive wheels slip, the relative relationship between the number of rotations of the travel motor, that is, the number of travel pulse signals, and the travel distance becomes erroneous, which is detected by pulse pickup III. Travel distance (or speed) calculated from the number of travel pulse signals
An error occurs between the distance traveled (or speed) and the actual distance traveled, which causes variations in the time required to travel a certain distance.

Additionally, in the case of the latter method of using a measuring wheel among conventional speed control methods, the measuring wheel tends to bounce or vibrate from side to side when the traveling speed is high, and as a result, it is difficult to accurately measure distance etc. when traveling at high speed. Therefore, measurements are carried out by lowering the measuring wheel to the ground only when driving at very low speeds, where highly accurate speed control is required, and during normal high-speed driving, the measuring wheel is raised and placed in a non-operating state. Speed control etc. are performed based on the generated running pulses.

However, when the above-mentioned elevating measuring wheel is used, it is lowered and touched to the ground when driving at very low speeds, and is activated, and during normal high-speed driving, the measuring wheel is raised and switched to the inactive state, but the measuring wheel is not activated. If a discrepancy occurs in the position information of the measuring wheel due to a malfunction in the lifting mechanism or a malfunction in the upper and lower limit position detection circuit of the measuring wheel of the meter control device, incorrect data may be input as the number of travel pulses of the automatic guided vehicle, resulting in inappropriate data being input. There was a risk that speed control would be carried out. In particular, when speed control is performed with a high resolution when traveling at very low speeds, there is a risk that malfunctions will increase to the extent that the resolution is increased, causing the automatic guided vehicle to run out of control.

Furthermore, Japanese Patent Publication No. 56-13324 discloses a method 11' to control the running of an unmanned vehicle by detecting an abnormal pulse. 1 device is described. This detects abnormal pulses from the pulse signals output from the differential amplifier circuit according to the detection voltage of the guide wire by the pickup coil when the automatic guided vehicle meanderes so much that it is about to deviate from the track. , which automatically slows down the vehicle for a certain period of time and issues an alarm to notify the supervisor, can prevent the automatic guided vehicle from running out of control due to meandering, but can also detect abnormalities such as equipment failure or drive wheel slippage. I can't.

This invention was made in view of the above-mentioned problems, and prevents inappropriate speed control due to measurement errors in mileage due to failure of measuring equipment or slippage of drive wheels, and also prevents discrepancies in position information of elevating measurement wheels. The purpose of this research is to provide a method for controlling the running of an automated guided vehicle that prevents runaway behavior due to

Means for Solving the Problems As a means for solving the above-mentioned problems, the automatic guided vehicle travel control method of the present invention is designed to prevent an error between the predetermined number of travel pulses and the number of travel pulses detected during actual travel. In an automatic guided vehicle travel control method that corrects the travel speed according to the error in the number of travel pulses when a pulse generator occurs, the pulse generator is The number of running pulses generated and the number of running pulses output by the pulse pickup device due to the rotation of the running motor are compared during actual driving, and when the difference between the number of running pulses exceeds a certain value, equipment failure or The system is characterized in that it determines that an abnormality such as slipping of the running wheels has occurred and stops running.

By adopting the method described above, the automated guided vehicle is equipped with an elevating measurement wheel that transmits rotation to the pulse generator to operate it, so that it touches the ground and rotates when lowered while traveling, and a pulse pickup. A device is provided to be able to detect the rotation of the travel motor, and during actual travel, the measuring wheel is lowered and grounded, and the number of travel pulses generated by the pulse generator is compared with the number of travel pulses detected by the pulse pickup device. The occurrence of an abnormality is detected when the difference between the numbers of both running pulses exceeds a certain value, and the vehicle is immediately decelerated to stop running.

EXAMPLE Hereinafter, an example in which the method of the present invention is applied to a method for controlling the running of an automatic guided vehicle operating at an extremely low speed on an automobile assembly line in tact operation will be described with reference to FIGS. 1 to 6. I will explain.

The automatic guided vehicle 1 that runs on the parts packaging line is a tricycle that is steered by one wheel at the front and driven by two wheels at the rear.
A driver's seat 4 and a steering wheel 5 are installed on the driver's seat 3 on the top of the frame 2 in case of unexpected situations, but normally the driver's seat 4 and steering wheel 5 pick up the magnetic field of the guide wire laid on the driving path. It is detected and guided by a coil (not shown), and rear wheels 8, 8 (one not shown), which are driving wheels, are rotationally driven by the running motor 7, and the vehicle runs unmanned. In addition, the front of the vehicle (
An ultrasonic sensor 9 provided on the left side in Fig. 1 detects obstacles in a non-contact manner, and when an obstacle comes into contact with the bumper 10, a sensor (not shown) built into the bumper 10 detects the contact. The traveling motor 7 is respectively stopped. Further, an operating lamp 11 such as a tail lamp or a running lamp is installed on the rear upper surface of the frame 2, and the other end of the output shaft of the running motor 7 that rotationally drives the rear wheel 8 is equipped with an operating lamp 11 such as a tail lamp or a running lamp.
A pulse counter 12 for normal high-speed running is attached, and constantly measures pulses generated by the rotation of the running motor 7.

On the other hand, the front wheel 13, which is a non-driving wheel, has a front fork (
The steering wheel is supported by a steering wheel (not shown) and disposed substantially on the center line of the body, and is driven by a steering motor (not shown) for automatic steering.

A measuring wheel 14 is disposed approximately in the center of the lower surface of the vehicle body, and as shown in FIG. 2, this measuring wheel 14 is parallel to the vehicle at regular intervals and located at the front 111Il (on the left side in FIG. 2) in the direction of travel. The base end is supported by the bin 75 on the frame 2111Il of the vehicle body so that the rear side in the direction of travel is lower, and between the lower ends of a pair of arms 16a and 16b arranged to be swingable in the vertical direction, a shaft is attached to the support shaft 14a. It is rotatably supported. Further, both arms 16
a and 16b are biased downward by the elastic force of a coil spring 17 wound around the outer periphery of a collar mounted on the bottle 15, and the measuring wheel 14a supported between the lower ends of both arms 16a and 16b is It is designed to come into contact with the running road surface with a predetermined pressing force.

Further, a drive pulley 19 on which a timing belt 18 is wound around the support shaft 14a of the measurement wheel 14 is connected to the support shaft 14a of the measurement wheel 14.
It is attached so that it rotates together with the support shaft 14a when the support shaft 14a rotates. Furthermore, the one arm 16
A rotary encoder 20 with a built-in pulse pickup is attached to b via a bracket, and the timing belt 18 is wound around a driven pulley 21 attached to the input shaft of the rotary encoder 20, and the rotation of the measuring wheel 14 is However, the indicated area 14a.

Drive pulley 19. The pulse is transmitted through the timing belt 18 and the driven pulley 21 to rotate the input shaft of the rotary encoder 20, and the pulse pickup detects the running pulse generated at a certain time.
It is configured to be able to measure travel distance or speed.

Further, both arms 16 supporting the measuring wheel 14 between their lower ends
Above a and 16b, a lifting motor 22 is attached to the traveling motor 7 and pulse counter 12 fixed to the frame 2 via a bracket 23, and the output shaft of the four lowering motors 22 is decelerated. The output shaft 24a of the reducer 24 is connected to the input shaft of the reducer 24, and a T-shaped lever 25 is connected to the output shaft 24a of the reducer 24 so as to rotate together with the output shaft 24a.
is installed.

Dogs 25a, 25a are formed at opposite ends of the T-shaped lever 25, respectively, and when the T-shaped lever 25 is rotationally driven, both the dogs 25a, 25a are
The lifting motor 2 contacts a limit switch 27 attached to the frame 2 of the vehicle body via a bracket 26.
It is designed to control the start and stop of 2. moreover,
A link 28 having a slit 28a in the longitudinal direction (vertical direction in FIG. 2) is rotatably connected to the lower end of the remaining arm extending downwardly of the T-shaped lever 25 by a pin 29. At the lower end of this slit 28a,
The arms 16a and 16b are suspended by the link 28 by engaging the slide bin 30 provided on the upper side of the lower end of the one arm 16a, and the arms 16a and 16b are lowered and measured due to unevenness of the running road surface. The wheel 14 is locked to allow it to rise when it runs over an obstacle.

The elevating measuring wheel 14 is used when the automatic guided vehicle 1 is running at high speed and when the pulse counter 12 of the traveling motor 7 alone measures the pulse counter 12 and the measuring wheel 14 is not required. The measurement wheel 14 is raised to put it in a non-operating state, and when driving at very low speeds that require highly accurate speed control, the measurement wheel 14 can be lowered to touch the ground and switched to an operating state. , lifting motor 2
2, turn the ■-shaped lever 25, and link 2.
8 and the slide bin 30 is locked to the lower end of the slit 28a, thereby driving the arm 16a upward.
The measuring wheel 14 and the rotary encoder 20 rise together. When the measuring wheel 14 reaches its upper limit and becomes inactive, the dog 25a at one end of the T-shaped lever 25 rotates to the limit switch 27 position to stop the lifting motor 22.

In addition, when switching the automatic guided vehicle 1 from normal running with the measuring wheel 14 inactive to ultra-low speed running, the measuring wheel 14 located at the upper limit operates the lifting motor 22 to move the T-shaped lever 25. When rotated, the link 28 descends, and the arm 16 engages the slide bin 30 with the slit 28a.
a is pushed down by the elastic force of the coil spring 17, and the measuring wheel 14 and rotary encoder 20 move down together. Then, when the measuring wheel 14 reaches its lower limit and comes into contact with the running road surface and is activated, the T-shaped lever 2
5 rotates to the limit switch 27 position to stop the lifting motor 22.

In addition, the automatic guided vehicle 1 is controlled by a W control device (not shown), and can run at two speeds: normal running at high speed and ultra-low speed running that matches the production tact (operating time ÷ production amount) of the parts packaging line. The system is designed to be able to switch to an unmanned mode, guided by a guide line laid on the driving path, and automatically when it detects a sign indicating the start of ultra-low speed driving, such as a mark plate installed near the guide line. The vehicle is then switched to ultra-low-speed driving mode, and first, the vehicle is decelerated and controlled to perform ultra-low-speed driving such as synchronous driving.

Furthermore, during normal running, when the running speed changes due to the influence of changes in load when the load is increased or decreased, the number of running pulses detected by the pulse counter 12 provided in the running motor 7 and the predetermined pulse Depending on the difference from the number of signals,
It is controlled to automatically correct the driving speed.

On the other hand, when running at a very low speed, the normal running mode is switched to the very low speed mode, and the measuring wheel 14 is lowered and rotated in contact with the running road surface. The rotation of the measuring wheel 14 is caused by a drive pulley 19. Timing belt 18. Driven pulley 2
0 to the input shaft of the rotary encoder 20, and as the input shaft of the rotary encoder 20 rotates, a pulse signal is generated. Then, the running pulse signal generated by the rotary encoder 20 is detected by a built-in pulse pickup, and compared with the running pulse signal detected by the pulse counter 12 provided in the running motor 7, and the number of both running pulse signals is calculated. If the difference exceeds a certain value, it is determined whether the pulse counter 12 or rotary encoder 20 has malfunctioned or
Alternatively, it is determined that the input pulse is unstable due to slipping of the rear wheels 8, which are the driving wheels, due to freezing of the running road, etc., and the vehicle is controlled to immediately decelerate and come to a stop.

This control program, as shown in the block diagram in FIG. The signal is set to the same level and compared, and the occurrence of an abnormality is detected when the difference in the number of both pulse signals exceeds a certain value.

In addition, when carrying out loading and unloading of the measuring wheel 14, as shown in the block diagram shown in FIG. If the lifting and lowering operation is not completed, it is determined that some abnormality has occurred in the lifting mechanism of the measurement wheel, and the wheel is controlled to stop the lifting and lowering operation of the measurement wheel, and to slow down and stop running.

In addition, when the measuring wheel 14 is not moved up and down, as shown in the block diagram shown in FIG. While detecting whether it is at the upper limit position, it is compared with the position information of the measurement wheel 14 stored in the control device, and if a difference is detected, it is controlled to determine that there is an abnormality and stop traveling.

Note that when switching from ultra-low-speed driving to high-speed normal driving, the measuring wheel 14 is raised to a non-operating state, and
When switching from normal running to very low speed running, the operation may be performed according to data on the operating state and non-operating state of the measuring wheel 14 stored in the control device.

Next, the case of controlling the travel of an automatic guided vehicle traveling at a very low speed on a parts packaging line will be described with reference to the travel control flowchart shown in FIG.

Note that the speed control program installed in the control RN device allows the input section of the driving pulse signal to be switched to a high-resolution ultra-low-speed driving mode when transitioning from normal driving to ultra-low-speed driving.

Now, the automatic guided vehicle 1, which is normally traveling at high speed outside the parts packaging line while towing a trolley loaded with parts such as packing pallets, approaches the parts packaging line and notices a mark plate provided on the traveling road surface. When a sign indicating the start of ultra-low speed driving is detected, the system stops! At the same time as the lJ device operates and decelerates, the driving pulse input section of the control device is switched to ultra-low-speed driving mode, a speed control program for ultra-low-speed driving (omitted) is started, and speed control is performed in parallel. This prevents runaway due to malfunction of the pulse counter 12 and rotary encoder 20 during ultra-low speed driving, and reduces the total distance traveled by 1 liter due to slippage of the rear wheels 8, which are the driving wheels.
A travel control program for abnormality detection to prevent the occurrence of the llJvA difference is started, and abnormality detection of input pulses is performed.

When the travel control program starts, first step 1
Normal running control is performed at pulse counter 1.
2 and the rotary encoder 20 start, and the pulse signal from the rotary encoder 20, which has been converted to the high-resolution ultra-low-speed driving mode for speed control during ultra-low-speed driving in step 2, is changed to the normal driving mode. It is reconverted to reduce the resolution to the same level as the pulse signal from the pulse counter 12, and the process proceeds to step 3.

In step 3, it is checked whether the vehicle has traveled a predetermined distance in order to compare the numbers of both travel pulse signals, and if the vehicle has not traveled the predetermined distance, the process proceeds to step 6, in which the vehicle travels the predetermined distance. If it has been completed, the process advances to step 4, in which the numbers of both traveling pulse signals are compared, and the process advances to step 5.

In step 5, the difference between the numbers of both traveling pulse signals is read, and if the difference is greater than a certain value, it is determined that an abnormality has occurred, and the vehicle is immediately braked to decelerate and stop traveling. If the difference is less than a certain value, it is assumed that there is no abnormality and the vehicle continues to run at very low speed, and proceeds to step 6.

After returning to the ultra-low speed running mode in step 6, the process returns to step 1 and the above processes are repeated to detect an abnormality.

As described above, in this embodiment, the rotary encoder 20 is not directly connected to the measuring wheel 14, but the timing belt 18
Since the rotation is transmitted through the measuring wheel 14, damage to the rotary encoder 20 due to impact from the measuring wheel 14 can be prevented.

In this embodiment, when the measuring wheel 14 is moved up and down, the time required for the up and down movement is measured by a hard timer in the central processing unit of the lifting device, and if the up and down movement is not completed within a certain period of time, the measuring wheel 14 is moved up and down. It was determined that some kind of abnormality had occurred in the elevating mechanism of the measuring wheel 14, and the elevating and lowering movement of the measuring wheel 14 was stopped, and the control was made to decelerate and stop the movement, thereby preventing runaway due to input of incorrect data due to malfunction. can be prevented. In addition, when the measuring wheel 14 is not moved up and down, the state of the measuring wheel 14 is detected as being in the lowered position where it is in an operating state or in the upper position where it is in an inactive state, and the measuring wheel 14 stored in the control device is detected. If a discrepancy is detected, it is determined that there is an abnormality and the travel is stopped, which has the effect of preventing the input of erroneous data.

In the above embodiment, a case has been described in which the present invention is applied to speed control when an automatic guided vehicle travels at extremely low speeds, but it can also be suitably implemented as a speed control method during normal travel.

As described in detail, the speed control method for an automatic guided vehicle according to the present invention transmits rotation to a pulse generator to operate the automatic guided vehicle, and when the vehicle is lowered during traveling, it touches the ground and rotates.

Since an elevating type measuring wheel is used, the measuring wheel can be raised to a non-operating state when measurement is not required, and therefore detection of unnecessary pulses can be prevented. In addition, when the number of running pulses generated by the pulse generator and the number of running pulses output by the pulse pickup device installed in the running motor are compared during actual operation, when the difference between the number of running pulses exceeds a certain value, In addition, it determines that an abnormality such as equipment failure or wheel slippage has occurred and controls the vehicle to decelerate and stop the vehicle, thereby preventing inappropriate speed control and improving the accuracy of speed control. It has effects such as being able to further increase the speed and preventing runaway.

[Brief explanation of the drawing]

FIG. 1 shows a control system 61 according to the control method of the present invention.
Figure 2 is a partially enlarged view showing the arrangement of the measurement wheel, Figure 3 is a block diagram for detecting abnormalities in the lifting and lowering movement of the measurement wheel, Figure 4 The figure is a block diagram for detecting an abnormality in the position of the measurement wheel, Fig. 5 is a block diagram for detecting a running abnormality, and Fig. 6 is a flowchart for detecting a running abnormality. 1... Automatic guided vehicle, 7.・・Travel motor, 12・
...Pulse counter, 13...Front wheel, 14...
Lifting measuring wheel, 16a, 16b...arm, 1
8...Timing belt, 19...Drive pulley, 20...Rotary encoder, 21...
Driven pulley, 22... Lifting motor, 25.
...T-shaped lever, 27...limit switch,
28...Link. Applicant Toyota Motor Corporation Meidensha Co., Ltd. Agent Patent Attorney Seal 1) Hisashi Take (one idiot) Figure 3

Claims (1)

[Claims] When an error occurs between the predetermined number of travel pulses and the number of travel pulses detected during actual travel, the travel control method for an automatic guided vehicle corrects the travel speed according to the error in the number of travel pulses. Compare the number of running pulses generated by the pulse generator by lowering and rotating the measurement wheel during running, and the number of running pulses output by the pulse pickup device as the running motor rotates, during actual running, A travel control for an automatic guided vehicle characterized by determining that an abnormality such as equipment failure or slipping of the traveling wheels has occurred and stopping the travel when the difference between the number of travel pulses exceeds a certain value. Method.