JP2008276605A - Traveling vehicle system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct an encoder value by an easy correction operation with one reference mark. <P>SOLUTION: A circulating distance L of a traveling route and division distances P obtained by dividing the distance into a plurality of pieces are stored, values c and d which satisfy e modP=d and e=cP+d are determined from an encoder signal e, and (c, d) is decided as a current position. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a traveling vehicle system such as an automatic guided vehicle, a tracked carriage, a stacker crane, and an overhead traveling vehicle.

In a system in which a plurality of traveling vehicles travel on the same route, each traveling vehicle exchanges current position data with each other to avoid interference (Patent Document 1: Japanese Patent Laid-Open No. 2005-196655). Here, when the detected mark of the linear sensor is provided over the entire length of the travel route and the accurate current position can be obtained by the linear sensor, the obtained current positions may be communicated with each other. However, in the case of a sensor that requires correction, such as an encoder, correction is required before the encoder value is communicated. In the correction of the sensor signal, it is considered that the ratio between the sensor signal and the actual travel distance is obtained and the sensor signal is constantly divided by this ratio. However, the division is repeatedly performed, and the burden on the control circuit side is large. Therefore, the inventor considered providing a plurality of calibration marks along the travel route and calibrating the sensor signal every time the calibration marks are passed. However, it is necessary to accurately determine the position of the calibration marks. The burden on the top is large.
JP 2005-196655 A

An object of the present invention is to facilitate the installation of a calibration mark for correcting the current position of a traveling vehicle and to simplify the correction calculation.
An additional problem in the second and third aspects of the invention is to shorten communication data between traveling vehicles when communicating the current position.
An additional problem in the invention of claim 4 is to avoid interference between traveling vehicles.
An additional problem in the invention of claim 5 is to make it possible to easily obtain the total length of the travel route.

A traveling vehicle system of the present invention is a system for traveling a traveling vehicle including a distance sensor for obtaining a position on the traveling route along the traveling route.
To the traveling car,
Means for determining the total length of the travel route;
The distance sensor signal when traveling the entire length of the travel route is defined as a route length L, and the route length L is virtually divided into m sections, and a signal to be compared with the distance sensor signal at the section break is stored. Storage means for
Each time the distance sensor signal reaches a section break, the section information, for example, the section number or ID is updated, and the current position calculating means for obtaining the increment of the distance sensor signal from the section break;
And is provided.
The division of the travel route is virtual in terms of control, and it is not necessary to actually provide a division mark along the travel route, and the distance sensor signal for the entire length of the route may be divided into m sections. Communication of the current position is performed directly between traveling vehicles or via a controller on the ground side.

Here, if the length P of each section is made common, a single data P may be stored as data for dividing the section, and communication of the current position of the traveling vehicle is simplified.
Further, if the length P of each section is L / 2 ⁿ (n is a natural number), the section information is displayed in binary when communicating the current position, and data from the section break is added to this. The data length for communication can be shortened.

  Preferably, a plurality of the traveling vehicles travel, a communication unit for communicating the section information and the increment with another traveling vehicle, the received section information of the other traveling vehicles, and the increment. Interference avoiding means for avoiding interference with the aircraft is provided. In order to avoid interference, the distance between vehicles is generally required, but only the difference in increments is used within the same section. If the sections are different, the length of the section is added to the difference in increments and converted to the actual distance from the reference mark. You don't have to. Alternatively, the current position may be converted into an actual distance from the reference mark to obtain the inter-vehicle distance between the own vehicle and another traveling vehicle.

  Preferably, the travel route is a round route, a reference mark is provided at one location along the travel route, a means for detecting the mark is provided on the traveling vehicle, and the travel route is detected after the mark is detected. A signal from the distance sensor until the mark is detected again after a round is taken as the route length L. The position of the reference mark itself is arbitrary, and installation accuracy is not necessary. When the travel route is a round trip route, reference marks are provided, for example, near both ends of the travel route, and the length corresponding to both ends of the travel route is obtained.

In the present invention, the signal obtained by the distance sensor is decomposed into section information and the increment of the distance sensor signal from the section break. The section is obtained by virtually dividing the entire length of the travel route into m, and a section division mark or the like is unnecessary. Although there is an error in the distance sensor, if the ratio of the lengths of the m sections is common among the traveling vehicles, the section breaks are common among the traveling vehicles. Next, there is an error proportional to the error of the distance sensor in the data indicating the position in the section, but this error is reduced when the length of the section is shortened.
In the present invention, there is no burden of dividing by a correction coefficient every time a distance sensor signal is obtained. Moreover, it is only necessary to appropriately set a reference mark at a position, or to detect that a traveling vehicle has passed a predetermined position with a limit switch or the like, and there is no need to install a plurality of division marks whose positions are known. In the present invention, by reducing the error of the distance sensor, it is possible to avoid interference between traveling vehicles and perform accurate stop control.

Here, if the length P of each section obtained by dividing the travel route is made constant, the section length can be easily stored. Further, when the travel route is divided into 2 ⁿ sections, the increment d and section information c are set to e with the distance sensor signal as e, and every time e reaches a multiple of P, the increment d is reset to 0 and the section information c is set to 1. It is obtained by changing. Further, the transmission data can be shortened by a binary notation of c and d.
When the section information and the increment are communicated between the traveling vehicles, the section information and the increment of the other traveling vehicles are received, thereby obtaining the inter-vehicle distance and avoiding the interference.
In particular, when a mark is provided at one place on the circuit route and the distance sensor signal from when the mark is detected until the mark is detected again is the length L of the travel route, the route length L can be easily obtained.

  In the following, an optimum embodiment for carrying out the present invention will be shown.

  1 to 5 show a traveling vehicle system and a modification of the embodiment. 1 to 4, 2 is a traveling vehicle system, 4 is a traveling route, and here is a circuit route, and an IC tag, a bar code, an optical mark, a magnetic mark, etc. at one appropriate position on the traveling route 4 A reference mark 6 is provided. The reference mark 6 does not need to be provided at a specific position such as the travel origin. Reference numeral 8 denotes a station, in which a plurality of traveling vehicles 10 travel around along the traveling route 4, and the current position is communicated between the traveling vehicles 10 and reported to the controller 12. Then, the controller 12 assigns a conveyance command to the traveling vehicle 10. The type of the traveling vehicle 10 is assumed to be an automatic guided vehicle traveling on the ground, a tracked carriage or stacker crane traveling on the ground with a track, or an overhead traveling vehicle.

  FIG. 2 shows a travel control system in the traveling vehicle 10. The encoder 14 may obtain a signal e (encoder signal) representing the travel distance along the travel route 4 and simply output a pulse train representing the rotation speed of the motor shaft or the like instead of outputting the signal e. The mark sensor 16 includes an RFID reader, a barcode reader, an optical sensor, a magnetic sensor, and the like, and detects the reference mark 6. The communication unit 18 communicates with other traveling vehicles and the controller 12 to report the current position, receives the current position of the other traveling vehicle, receives a conveyance command from the controller 12, and reports a conveyance result. The interference avoidance unit 20 calculates an inter-vehicle distance from other traveling vehicles to avoid interference. The calculation unit 22 performs calculations necessary for controlling the traveling vehicle 10. For example, when the encoder 14 obtains a lap distance L when the vehicle travels around the travel route 4, this distance is divided by a predetermined division number m, and the division distance is calculated. Find P. The division number m is, for example, a power of 2. In addition, when the calculation unit 22 receives the current position of another traveling vehicle from the communication unit 18, the calculation unit 22 obtains an inter-vehicle distance from the own vehicle.

The lap distance storage unit 24 detects the signal e from the encoder 14 until the reference mark 6 is detected once again after the reference mark 6 is detected when the traveling vehicle 10 makes a round of the travel route 4 as a test run. Is stored as the rounding distance L. The division distance storage unit 26 stores the division distance P when the rounding distance L is equally divided into 2 ⁿ (n is a natural number) sections, and L = 2 ⁿ × P. The position counter 28 counts the distance d at which the signal of the encoder 14 is reset to 0 at the break of the divided section and the section number c (c is a natural number or 0). The position counter 28 resets the distance d to 0 each time the encoder signal e becomes a multiple of the division distance P, and adds 1 to the section number c. Instead of incrementing the section number c by one, the section number c may be subtracted one by one from 0 to a negative value. The counter value d is increased by the pulse from the encoder 14,
e modP = d, e = cP + d

  FIG. 3 shows the configuration of the position counter 28. The encoder 14 comprises a pulse generator 30 and a counter 31. The pulse generator 30 monitors the rotational speed of the motor shaft and the like to generate a pulse train, and adds the counter 31 with this pulse train to output an encoder signal e. The counter 31 may not be provided. The position counter 28 includes a counter 32, a comparison unit 33, and a register 34. The counter 32 is added by the pulse train of the pulse generator 30 and the output d is input to the comparison unit 33. The comparison unit 33 compares the output d of the counter 32 with the division distance P, and if they match or d exceeds the division distance P, the counter 32 is reset to zero. Simultaneously with the reset of the counter 32, the value of the register 34 is incremented by one. When the mark sensor detects the reference mark, both the counter 32 and the register 34 are reset to zero. In addition, when the travel distance for one round of the travel route 4 is obtained by the counter 32, the signal of the pulse generator 30 may be added without resetting the counter 32 to 0 for one round.

FIG. 4 shows an acquisition algorithm for the current position in the embodiment. In order to acquire the lap distance L, each traveling vehicle goes around the travel route 4 once. When the reference mark is detected, the encoder value e is reset to 0, and when the reference mark is detected again after one round, the encoder value e is stored as the circulation distance L. Further, the circulation distance L is equally divided by 2 ⁿ and stored as the division distance P. The lap distance L and the divided distance P are calculated for each traveling vehicle 10, and the divided distance P is calculated by the controller 12 by transmitting the circulated distance L to the controller 12 even if each traveling vehicle 10 performs the calculation independently. The divided distance P may be received.

In acquiring the current position, the encoder value is reset to 0 each time a reference mark is detected, and the outputs c and d of the position counter 28 are both reset to 0. Instead of resetting the encoder value e to 0, an increment of the encoder value after detecting the reference mark 6 may be used. In synchronization with the increase of the encoder value e, the counter value d is added, and when d is P or more,
It is assumed that d = d−P and c = c + 1. Then, the obtained combination of c and d is transmitted to other traveling vehicles and the controller 12 as data representing the current position. Next, the current position data (c ′, d ′) is received from another traveling vehicle, and the inter-vehicle distance is calculated. For example, it is assumed that the following traveling vehicle avoids the interference, and it is confirmed which traveling vehicle is ahead by comparing the section number c and the traveling distance d in the section. In the same section, by comparing d and d ′, if the sections are different, the distance between vehicles d is calculated in consideration of the distances d and d ′ in the section and the distance P per section. To avoid interference based on

  In this way, it is possible to easily avoid interference between traveling vehicles. In order to avoid interference, the reference mark may be installed at an appropriate position along the travel route, and the installation accuracy is not important. Further, it is not necessary to install division marks whose positions are known at a plurality of locations along the travel route. Further, it is not necessary to obtain a correction coefficient for each encoder and divide the encoder value continuously. Accordingly, it is possible to easily set the reference mark and obtain the current position data in which the encoder error is easily corrected.

  If the division distance differs by section without equally dividing the circulation route, the division distance for each section is stored in a table (not shown), and the distance d matches the division distance stored in the table by the comparison unit 33 in FIG. If detected, the counter 32 is reset and the register 34 is incremented by one.

  In the embodiment of FIGS. 1 to 4, the traveling vehicle 10 traveling around the traveling route 4 is shown. Instead, FIG. 5 shows an example of a system using stacker cranes 52 and 53 that reciprocate along the traveling rail 51. 50 is a traveling vehicle system of a modified example, 51 is a traveling rail, and the stacker crane No. 1 52 and No. 2 53 run, and the traveling rail 51 is divided into three ranges, a left and right non-interference range and a central interference range. It is done. Reference numerals 54 and 55 are reference marks, and the stacker cranes 52 and 53 are provided with mark sensors 56 and 57 to detect the marks 54 and 55.

The stacker cranes 52 and 53 obtain the travel distance between the reference marks 54 and 55 with an encoder, respectively, and divide them into (2 ⁿ -2) sections, and further, the sections with the same division distance on the left and right of the marks 54 and 55. Are added one by one. The total number of divisions is ²ⁿ , and the division distance of each section is constant. Here, if the division distance P is set to be slightly larger than ½ of the vehicle body length of the stacker cranes 52 and 53, interference between the stacker cranes 52 and 53 is added by adding one section to the left and right of the reference marks 54 and 55. The current position in the range can be expressed by the distance obtained by the encoder based on the section number and the section break. The section is, for example, the section on the left side of the reference mark 54 is the section 0, the section on the right side of the reference mark 55 is the 2 ⁿ -1th section, and the distance data in each section is, for example, 0 at the left end of the section. Determine to be P at the right end.

  In this way, the meanings of the section number and the distance data in the section are common between the first machine 52 and the second machine 53. The first machine 52 and the second machine 53 notify each other of the current position in the form of a section number and a distance within the section by a communication unit (not shown), and there is no possibility of interference when in the non-interference range. Notice. The first car 52 and the second car 53 obtain the inter-vehicle distance from the received current position data of the other party and avoid interference. The other points are the same as those of the embodiment of FIGS.

Instead of providing the reference mark 6, a limit switch or the like may be provided at one place on the circuit travel route, and when the traveling vehicle 10 is detected, that fact may be communicated to the traveling vehicle 10. In this case, the traveling distance at the encoder until the traveling vehicle 10 receives the communication and receives it again becomes the traveling route length. Furthermore, it is preferable that the encoder value is reset when the travel route is made a round, both when the reference mark 6 is provided and when a limit switch is provided. Although it is preferable to reduce the burden on the controller 12 and reduce the time lag by directly communicating between the traveling vehicles 10, the communication may be performed via the controller 12.

Block diagram of the traveling vehicle system of the embodiment The block diagram which shows the traveling control system with the traveling vehicle of execution example Block diagram of encoder and position counter in the embodiment The flowchart which shows the present position acquisition algorithm in an Example Block diagram of a modified traveling vehicle system

Explanation of symbols

2 Traveling vehicle system 4 Traveling route 6 Reference mark 8 Station 10 Traveling vehicle 12 Controller 14 Encoder 16 Mark sensor 18 Communication unit 20 Interference avoidance unit 22 Calculation unit 24 Storage unit 26 for the lap distance L Storage unit 28 for the division distance P Position counter 30 Pulse generator 31, 32 Counter 33 Comparison unit 34 Register 50 Traveling vehicle system 51 Traveling rail 52, 53 Stacker crane 54, 55 Reference mark 56, 57 Mark sensor

Claims (5)

In a system for traveling a traveling vehicle having a distance sensor for obtaining a position on the traveling route along the traveling route,
To the traveling car,
Means for determining the total length of the travel route;
The distance sensor signal when traveling the entire length of the travel route is defined as a route length L, and the route length L is virtually divided into m sections, and a signal to be compared with the distance sensor signal at the section break is stored. Storage means for
Updating the section information every time the signal of the distance sensor reaches the break of the section, and a current position calculating means for obtaining the increment of the signal of the distance sensor from the break of the section;
And a traveling vehicle system. 2. The traveling vehicle system according to claim 1, wherein the length P of each section is made common. The traveling vehicle system according to claim 2, wherein the length P of each section is L / ²ⁿ (n is a natural number). While traveling a plurality of the traveling vehicles, a communication unit for communicating the section information and increments with other traveling vehicles, and the received section information and the increments of other traveling vehicles, The traveling vehicle system according to claim 1, further comprising interference avoiding means for avoiding the interference. The travel route is a round route, and a reference mark is provided at one location along the travel route,
A means for detecting the mark is provided in the traveling vehicle, and a signal from the distance sensor from when the mark is detected until the mark is detected again after going around the driving route is set as the route length L. The traveling vehicle system according to claim 1, wherein:

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