JP7151925B1 - Automatic guided vehicle control method, control device, and computer program - Google Patents

Abstract

A control method, a control device, and a computer program for an automatic guided vehicle capable of controlling backward movement are provided. A control method for controlling driving wheels of an automatic guided vehicle by a computer, wherein a towed vehicle is connected by a connecting shaft so as to be rotatable left and right with respect to a traveling direction of the automatic guided vehicle, and When the computer receives an instruction to move backward, the computer sets the connection angle of the towed vehicle on the connection shaft, and adjusts the lateral rotation amount of the drive wheels to move the automatic guided vehicle backward while maintaining the set connection angle. and controlling the drive wheels based on the calculated amount of rotation. [Selection drawing] Fig. 1

Description

The present invention relates to a control method, a control device, and a computer program for an automatic guided vehicle that tows a towed vehicle.

At production sites such as factories, automatic guided vehicles (such as automatic guided vehicles) that transport goods such as materials, parts, and finished products are in widespread use. Automatic guided vehicles include a type that has its own platform to carry items, a type that lifts up a basket on which items are placed and transports it, and a type that tows a basket vehicle (towed vehicle) that stores items. It has various types including type.

Patent Literature 1 discloses a control method during towing. In Patent Document 1, a camera provided toward the rear of the towing vehicle is used to calculate a bending angle (connection angle) of a connecting portion from an image of a marker attached to a member to be connected of the towed vehicle. The connecting portion between the towing vehicle and the towed vehicle disclosed in Patent Document 1 includes a connecting shaft provided in the vertical direction at the tip of a rod-shaped connecting member projecting rearward of the towing vehicle, and the towed vehicle. A connecting hole provided in the vertical direction is engaged with the tip of a rod-shaped connecting member projecting forward of the .

A towing type automatic guided vehicle captures an image of a floor surface marked with a specific line, and controls the vehicle to travel along the line based on the captured image. When moving forward, the towed vehicle naturally follows the AGV, but when reversing, the drive wheels are only on the AGV, so the bending angle at the connecting part tends to increase, and when it reaches its limit, It is difficult to control, for example, it becomes impossible to continue retreating any more. Therefore, the automatic guided vehicle to which the towed vehicle is coupled is backed up by a method in which the unmanned guided vehicle crawls under the towed vehicle and lifts up, as in Patent Document 2.

JP 2019-199150 A JP-A-6-135321

Reverse movement of the automatic guided vehicle is necessary to automatically connect the automatic guided vehicle with the towed vehicle at the target position without the assistance of the operator, or to automatically disconnect the towed vehicle. Become. This is because, if an unmanned guided vehicle traveling only forward along a specific line separates the towed vehicle at a specific position, the traveling of the following unmanned guided vehicle is hindered. However, if it is limited to lift-up when moving in reverse as in Cited Document 2, the shape and weight of the towed vehicle are limited. In order to realize automatic connection and disconnection of the towed vehicle while the automatic guided vehicle and the towed vehicle remain connected, a control method during reverse movement becomes an issue.

Patent document 1 is based on the premise that the tow vehicle is driven by a human, not an automatic guided vehicle, so that the driver can recognize the connection angle of the connection portion, thereby improving the driving accuracy when moving in reverse. , how it should be controlled depends on the skill of the driver.

The unmanned guided vehicle tends to maintain or converge the initial connection angle of the connection portion during forward movement, but tends to maintain or diverge the initial connection angle during backward movement. Therefore, it becomes a problem to realize control that does not diverge the coupling angle in the backward operation.

When the automated guided vehicle moves backward on a straight track, it is sufficient to simply maintain the connection angle of the connecting part at zero. A control is needed to maintain a constant articulation angle that can be geometrically calculated from . In order to maintain the connection angle, control is required to correct the deviation between the target connection angle and the actual connection angle. In addition, when the backward traveling distance is long or when high positional accuracy is required, disturbances such as road surface distortion and external forces affect the coupling angle, so maintaining the coupling angle alone may cause the vehicle to deviate from the target trajectory. is high. Control is also required to correct the deviation between the target trajectory and the actual traveling trajectory.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control method, a control device, and a computer program for an automatic guided vehicle capable of controlling back movement.

A control method for an automatic guided vehicle according to an embodiment of the present disclosure is a control method in which a computer controls driving wheels of an automatic guided vehicle, and a towed vehicle rotates left and right with respect to a traveling direction of the automatic guided vehicle. When receiving a backward instruction, the computer sets a connection angle of the towed vehicle on the connection shaft and causes the automatic guided vehicle to move backward based on the set connection angle. to calculate the amount of left and right rotation of the drive wheel, and control the drive wheel based on the calculated amount of rotation.

A control device for an automatic guided vehicle according to an embodiment of the present disclosure is a control device that includes a control unit in which a computer controls drive wheels of the automatic guided vehicle, wherein the towed vehicle is positioned in the traveling direction of the automatic guided vehicle. When receiving an instruction to move backward, the control unit sets a connection angle of the towed vehicle at the connection shaft, and based on the set connection angle, the unmanned guided vehicle. The amount of left and right rotation of the drive wheels for moving the vehicle backward is calculated, and the drive wheels are controlled based on the calculated amount of rotation.

A computer program according to an embodiment of the present disclosure is a control process in a state in which a towed vehicle is connected to a computer that controls driving wheels of an automatic guided vehicle by a connecting shaft so as to be rotatable left and right with respect to the traveling direction. for setting a connection angle of the towed vehicle on the connection shaft and causing the automatic guided vehicle to move backward based on the set connection angle when the computer receives a backward instruction. A process of calculating the amount of left and right rotation of the drive wheels and outputting a control signal for controlling the drive wheels based on the calculated amount of rotation is executed.

In the automatic guided vehicle control method, the control device, and the computer program of the present disclosure, when the towed vehicle is rotatably connected to the connection shaft, the computer causes the automatic guided vehicle to move backward based on the connection angle. It calculates and controls the wheel speed (rotational speed). By controlling the connection angle so that it does not exceed a predetermined value or by maintaining it at a specific angle, the situation where the towed vehicle and the unmanned guided vehicle bend excessively so that they cannot move backward, It is possible to automatically control the backward movement while avoiding the situation where the towing vehicle meanders.

In the control method for an automatic guided vehicle according to an embodiment of the present disclosure, the computer acquires a captured image from an imaging unit that captures an image of the rear of the automated guided vehicle, and based on the acquired captured image, determines the straight line of the towed vehicle. Alternatively, the deviation between the target trajectory including the curve and the towed vehicle is calculated, and the upper limit corresponding to the calculated deviation is calculated from the upper limit of the correction value of the coupling angle stored in advance in the storage unit according to the magnitude of the deviation. The value is read, and the range of connection angles is set within a range not exceeding the upper limit.

In the control method for an automatic guided vehicle of the present disclosure, when an automatic guided vehicle connected to a towed vehicle moves backward on a specific target track by recognition processing in a captured image, the towed vehicle moves to the target track. By setting different upper limits for the adjustment range of the coupling angle for returning to the target trajectory depending on whether the deviation is large or small, it is possible to avoid situations where the towed vehicle meanders and does not converge to the target trajectory. Become.

In the control method for an automatic guided vehicle according to an embodiment of the present disclosure, the computer derives and sets the connection angle using the following equations (1) to (3).
Angle POR=φ2=arcTAN(L2/r2) (1)
Radius r=r2/COSφ2 (2)
θ=arcSIN(L1/r)+arcSIN(L2/r) (3)
O: The point where the extension of the rotation axis of the drive wheel of the automatic guided vehicle and the extension of the rotation axis of the drive wheel of the towed vehicle intersect P: The center point of the connecting shaft Q: The rotation axis of the drive wheel of the automatic guided vehicle center point of R: center point of rotation axis of fixed wheel of towed vehicle
L1: Length of line segment PQ
L2: Length of line segment PR
r: Radius of rotation of point P centered on point O
r2: Radius of rotation of point R centered on point O θ: Connection angle (deviation between the traveling direction of the unmanned guided vehicle and the traveling direction of the towed vehicle)

In the method for controlling an automatic guided vehicle according to the present disclosure, Expressions (1) to (3 ), it is possible to set the coupling angle using the dimensional data of the towed vehicle and the automatic guided vehicle.

In the control method for an automatic guided vehicle according to an embodiment of the present disclosure, the computer uses a sensor that measures the connection angle on the connection shaft, and the actual connection angle measured by the sensor and the formula (1) A trajectory of the towed vehicle is derived based on equation (3).

In the automatic guided vehicle control method of the present disclosure, it is possible to calculate the connection angle for following the target trajectory using the dimensional data of the towed vehicle and the automatic guided vehicle.

In an automatic guided vehicle control method according to an embodiment of the present disclosure, the computer stores dimension data of the towed vehicle in advance in association with identification data for identifying the towed vehicle, The dimension data corresponding to the identification data of the vehicle is read, and the connection angle is calculated using the length L2 included in the dimension data in the above equations (1) to (3).

In the automatic guided vehicle control method of the present disclosure, the trajectory of the towed vehicle can be calculated from the dimensional data of the towed vehicle and the automatic guided vehicle and the connection angle at that time.

In the control method for an automatic guided vehicle according to an embodiment of the present disclosure, the computer is connected to the rear part of the automatic guided vehicle via the connecting shaft, and has an engaging portion that engages with the towed vehicle. It is provided in the connection device that connects.

The method for controlling an automatic guided vehicle of the present disclosure is performed by a coupling device that is attached to the automatic guided vehicle and engages with the towed vehicle to connect it to the automatic guided vehicle, so that the driving wheels of the automatic guided vehicle are connected to each other. It may be controlled, or may be performed by the control unit itself of the driving wheels of the automatic guided vehicle.

According to the present disclosure, it is possible to control backward movement while avoiding reaching the limit of the bending angle while the automatic guided vehicle and the towed vehicle are connected.

1 is a schematic side view of an automated guided vehicle, hitch and towed vehicle of the present disclosure; FIG. 1 is a schematic perspective view of an automatic guided vehicle and a coupling device; FIG. It is a block diagram which shows the structure of an automatic guided vehicle and a coupling device. FIG. 2 is a schematic diagram of travel control of an automatic guided vehicle V in a state where a towed vehicle T is towed; 4 is a flow chart showing an example of a reverse control procedure by a coupling device; FIG. 10 is a diagram showing a correspondence relationship between the deviation and the upper limit of the correction value of the connection angle; 4 is a graph showing the time transition of the deviation (position) of the position of the automatic guided vehicle V from the line L. FIG. The schematic diagram of the running control by a coupling device is shown. It is a block diagram which shows the structure of the automatic guided vehicle of 2nd Embodiment, and a connection apparatus. 4 is a schematic diagram of dimensional data; FIG. It is a figure which shows the driving|running example of the automatic guided vehicle in 2nd Embodiment. 9 is a flow chart showing an example of a control processing procedure by a control unit of the coupling device of the second embodiment; FIG. 4 is a diagram showing an example of a determined target trajectory; FIG. 4 is a diagram showing an example of control of a connection angle;

The present disclosure will be specifically described with reference to the drawings showing the embodiments thereof.

(First embodiment)
FIG. 1 is a schematic side view of an automatic guided vehicle V, a coupling device 1 and a towed vehicle T according to the first embodiment, and FIG. 2 is a schematic perspective view of the automatic guided vehicle V and coupling device 1. FIG.

The automatic guided vehicle V has a vehicle body 21 and wheels 22, as shown in FIGS. A vehicle body 21 of the automatic guided vehicle V has a substantially rectangular parallelepiped shape, and has a shape with an inclined surface corresponding to the rear portion. The vehicle body 21 has a pair of connecting members 23 extending rearward. The connecting member 23 has a connecting shaft 231 along the height direction (vertical direction) of the automatic guided vehicle V. As shown in FIG. A bottom portion 211 of the vehicle body 21 is provided with one front wheel 221 and two rear wheels 222 (one of which is not shown). The automatic guided vehicle V drives the rear wheels 222 as drive wheels under the control of the controller.

The connecting device 1 includes a base 10 , a connecting portion 11 , an engaging portion 12 and an imaging portion 13 . The base 10 has a flat rectangular parallelepiped housing and accommodates a controller 100 (see FIG. 3) therein. The connecting device 1 can be connected so as to be engaged with a connecting member 23 at the rear of the automatic guided vehicle V by a connecting portion 11 fixed to one wide surface of the housing. The connection part 11 is connected so as to be rotatable to the left and right with respect to the traveling direction of the automatic guided vehicle V. As shown in FIG. For example, the connecting part 11 is composed of a pair of connecting tools having a connecting hole to be fitted to the connecting shaft 231 of the connecting member 23 of the automatic guided vehicle V in the vertical direction. The connecting hole of the connecting portion 11 is provided so as to have an axial direction parallel to the long side direction of the wide surface of the housing of the base 10 .

As shown in FIG. 2 , the connecting device 1 is connected to the automatic guided vehicle V through the connecting shaft 231 of the automatic guided vehicle V through the connecting hole of the connector 111 . The connecting part 11 includes an encoder 112 that measures the amount of rotation between the connecting shaft 231 of the automatic guided vehicle V and the connecting hole. The encoder 112 uses, for example, a magnetic absolute encoder. The encoder 112 outputs a signal corresponding to the amount of rotation to the controller 100 provided inside the base 10 .

The engaging portion 12 is provided on the other wide surface of the base body 10 with a first actuator 121 which linearly moves along the long side direction of the wide surface and a second actuator 121 which linearly moves along a direction perpendicular to the wide surface (advancing direction). 122 and provided. The second actuator 122 is erected from the first actuator 121 and includes a rod 123 movable in the erection direction and a guide 124 for the rod 123 . The engaging portion 12 can engage with the towed vehicle T by gripping an object from the outside with a grip plate 125 fixed to the rod 123 and a grip plate 126 provided at the base end of the rod 123 .

The imaging unit 13 is attached so as to image one end surface of the rectangular parallelepiped main body, that is, toward the rear in the running direction of the automatic guided vehicle V. As shown in FIG. The imaging unit 13 may be composed of a plurality of imaging units. The imaging unit 13 may include not only the locations shown in FIGS. 1 and 2 but also other imaging units provided so as to view the rear from the bottom.

The vehicle T to be towed has a frame T1 in which L-shaped angles are assembled into a rectangle, wheels T2 provided at the bottom of the frame T1, and a basket T3 fixed on the frame T1. The basket T3 has a metal mesh on each side to prevent falling, but the present invention is not limited to this. The towed vehicle T is not particularly limited as long as it has wheels T2 and is called a so-called basket vehicle.

The connecting device 1 of the first embodiment can be attached to any automatic guided vehicle V having a connecting shaft 231 at its rear portion. The coupling device 1 communicates with a control unit that controls the traveling of the automatic guided vehicle V, and the control processing in the control unit provided inside the base body 10 allows the automatic guided vehicle V to control the driving of the rear wheels 222. Get and drive this back. Further, when the coupling device 1 approaches the towed vehicle T as shown in FIG. The directional cross members are engaged and connected to be gripped by grip plates 125 and 126 from below. The engagement method is not limited to this.

Note that the connecting device 1 may have a structure in which the connecting member 23 and the connecting shaft 231 are provided on the connecting device 1 side. In that case, even if the automatic guided vehicle V does not have the connection part 231 at the rear, if there is a structure that can fix the connection member 23 that is a part of the connection device 1 at the rear of the automatic guided vehicle V, the connection device 1 can be attached.

The contents of control processing in the control unit 100 of the coupling device 1 will be described below. FIG. 3 is a block diagram showing configurations of the automatic guided vehicle V and the coupling device 1. As shown in FIG.

The automatic guided vehicle V includes a rear wheel drive unit 220 and a control unit 200 that controls the rear wheel drive unit 220 inside the vehicle body 21 . The automatic guided vehicle V includes an imaging unit 201 inside the vehicle body 21 that can capture an image of the traveling direction including the floor surface in an imaging range during traveling. The control unit 200 is connected to the rear wheel driving unit 220 and the image capturing unit 201, and based on information obtained by image processing the image captured by the image capturing unit 201, the speed of each of the left and right wheels of the rear wheel 222 ( amount of rotation) to control the rear wheel drive unit 220 .

The control unit 200 controls the rotation amount between the connection shaft 231 and the connection hole in the connection portion 11 between the connection device 1 and the automatic guided vehicle V (the angle between the connection tool of the connection portion 11 and the connection member 23). Data on the amount of rotation may be acquired from the encoder 112 that measures the to execute the control.

The connecting device 1 includes a control section 100 inside the base 10 . The control unit 100 is a microcontroller and includes a processor 101 , a memory 102 and an input/output unit 103 .

The processor 101 uses a processor such as a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). Memory 102 is a non-volatile memory. The memory 102 stores a control program 1P and angle data. The angle data is data of the upper limit value of the connection angle correction value according to the deviation described later. The angle data may be data acquired by the control unit 100 via a communication medium (not shown). The control unit 100 may also include memories such as ROM (Read Only Memory) and RAM (Random Access Memory), timers, various sensors, and the like.

The input/output unit 103 is an input/output interface of the microcontroller. The processor 01 acquires image signals from the imaging unit 13 via the input/output unit 103 and outputs control signals to the drive circuit 1201 of the first actuator 121 and the drive circuit 1202 of the second actuator 122 . The input/output unit 103 is also connected to the encoder 112 , and the processor 101 acquires a signal corresponding to the amount of rotation output from the encoder 112 . The input/output unit 103 is also connected to the control unit 200 of the automatic guided vehicle V, and the processor 101 can exchange data with the control unit 200 .

When the automatic guided vehicle V moves forward, it basically automatically travels along a line L of a specific color marked on the floor surface. The automatic guided vehicle V recognizes the range of the line L from the image captured by the imaging unit 201 provided facing the floor of the vehicle body 21, and makes the deviation between the position of the automatic guided vehicle V and the line L zero. The left and right speeds (rotation amounts) of the rear wheels 222 are respectively controlled so as to bring them closer to each other. In the first embodiment, even when the automatic guided vehicle V moves backward, it travels along the line L in the direction of travel by using the imaging unit 13 or another imaging unit that takes an image of the rear under the control of the coupling device 1 .

FIG. 4 is a schematic diagram of travel control of the automatic guided vehicle V with the towed vehicle T towed. The schematic diagram of FIG. 4 shows an example of general cruise control. 4A to 4E show how the robot moves backward along the line L. FIG. 4A to 4E are illustrated with a large distance between the towed vehicle T and the line L to simplify the explanation. 4A shows a state in which the connecting member 23 of the automatic guided vehicle V and the connecting portion 11 of the connecting device 1 are in a straight line, and the connecting angle θ is 0 (zero) degrees. During backward movement, the coupling device 1 controls the coupling angle θ between the coupling portion 11 of the coupling device 1 and the coupling member 23 of the automatic guided vehicle V to be larger as shown in FIG. 4B. When the towed vehicle T approaches the line L, the coupling device 1 returns and decreases the coupling angle θ as shown in FIG. 4C. When the towed vehicle T gets on the line L, the coupling device 1 sets the coupling angle θ to the opposite side as shown in FIG. 4D. As a result, both the automatic guided vehicle V and the towed vehicle T begin to ride on the line L, as shown in FIG. 4E.

If the connection angle shown in FIG. 4B is set too large in the control shown in FIG. There is a high possibility that the deviation between the Therefore, the unmanned guided vehicle V and the connection device 1 of the first embodiment perform the following control in order to prevent the connection angle θ from being set excessively large as control when moving backward while towing the vehicle T to be towed. Control. Hereinafter, the control when the automatic guided vehicle V in a state of towing the towed vehicle T is reversed will be described with reference to a flow chart.

In the processing described below, the position deviation dx from the towed vehicle T with respect to the line L, which is the target trajectory, and the angle deviation dθ between the traveling direction of the towed vehicle T and the line L are used.

FIG. 5 is a flow chart showing an example of a reverse control procedure by the coupling device 1. As shown in FIG. The coupling device 1 is attached to the automatic guided vehicle V and connected to the vehicle T to be towed. Run.

The control unit 100 of the coupling device 1 determines whether or not a backward instruction has been received from the control unit 200 of the automatic guided vehicle V by the processing of the processor 101 (step S101). In step S<b>101 , the control unit 200 of the automatic guided vehicle V transmits a backward instruction to the control unit 100 of the coupling device 1 when the connected towed vehicle T reaches a place to retreat.

If it is determined that the reverse command has not been received (S101: NO), the control unit 100 returns the process to step S101 and waits until it determines that the reverse command has been received. If the control unit 100 determines that it has received a backward instruction (S101: YES), it acquires the right to control the rear wheel drive unit 220 for the rear wheels 222 from the automatic guided vehicle V (step S102). Thereafter, until the control right is relinquished, the rear wheel 222 is controlled by the control signal from the control unit 100, and the towed vehicle T and the coupling device 1 are forward, and the automatic guided vehicle V moves.

The control unit 100 acquires travel route information and calculates a reference angle (step S103). The reference angle serves as a reference for the connection angle when traveling on a traveling route (straight line, curve). The control unit 100 may acquire the reference angle from the control unit 200 of the automatic guided vehicle V, or may calculate the reference angle from the target trajectory using a predetermined algorithm.

The control unit 100 acquires an image from the image capturing unit 13 that captures an image of the rear of the automatic guided vehicle V, that is, the front during reversing (step S104), and based on the acquired image, the towed vehicle T and the target trajectory. A positional deviation dx and an angular deviation dθ between are calculated (step S105). In step S105, the control unit 100 calculates the distance between the intermediate position between the two fixed wheels of the towed vehicle T and the line L as the positional deviation dx. is calculated as the angle deviation dθ. When the target trajectory is curved, the control section 100 calculates the angle between the tangent line of the target trajectory appearing in the image acquired from the imaging section 13 and the center line of the towed vehicle T as the angle deviation dθ.

The control unit 100 reads out the upper limit value of the connection angle correction value corresponding to the positional deviation dx and the angular deviation dθ calculated in step S105 (step S106). When the deviation is small, the upper limit of the connection angle correction value is small, and when the deviation is large, the upper limit of the connection angle correction value is large (see FIG. 6).

The control unit 100 sets the allowable range of the connection angle using the upper limit value read in step S106 (step S107). In step S107, the control unit 100 sets the allowable range of the connection angle as follows.
Tolerance = reference angle ± upper limit of connection angle correction value

The control unit 100 acquires the actual coupling angle at that time from the encoder 112 (step S108). The control unit 100 determines whether or not the acquired actual connection angle at that time is within the allowable range of the connection angle set in step S107 (step S109).

If it is determined to be within the allowable range (S109: YES), the control unit 100 calculates the left and right speeds (rotation amounts) of the rear wheels 222 so as to reduce the deviation calculated in step S105 (step S110). ), and outputs a control signal indicating the left and right speeds to the rear wheel drive unit 220 (step S111).

The control unit 100 determines whether or not the automatic guided vehicle V and the towed vehicle T have reached their target positions (step S112). In step S112, the control unit 100 may determine whether or not the imaging unit 13 has captured an image of the target marker or the like, or may determine using another method.

When determining that the automatic guided vehicle V and the towed vehicle T have reached the target positions (S112: YES), the control unit 100 outputs a control signal to the rear wheel drive unit 220 to stop (step S113). The control unit 100 returns the control right of the rear wheel drive unit 220 to the automatic guided vehicle V (step S114), and ends the reverse control.

In step S109, if it is determined that the connection angle is not within the allowable range of the connection angle (S109: NO), the control unit 100 adjusts the left and right speeds of the rear wheels 222 so that the connection angle falls within the allowable range. (Amount of rotation) is calculated (step S115), and the process proceeds to step S111.

If it is determined in step S112 that the target position has not been reached (S112: NO), control unit 100 returns the process to step S104.

FIG. 6 is a diagram showing the correspondence relationship between the deviation and the upper limit of the correction value of the connection angle. In FIG. 6, the right side shows the magnitude of the deviation dx, and the left side shows the allowable range of the coupling angle corresponding to each deviation dx range. As shown in FIG. 6, the upper limit of the connection angle is set for each range of the positional deviation dx to the line L, which is the target position. In the example of FIG. 6, when the positional deviation dx is equal to or less than the first predetermined value, the upper limit of the correction value of the connection angle is α degrees, and when the positional deviation dx exceeds the first predetermined value and is equal to or less than the second predetermined value. If there is, the upper limit of the correction value of the connection angle is β degrees, and if the positional deviation dx exceeds the second predetermined value and is equal to or less than the third predetermined value, the upper limit of the correction value of the connection angle is γ degrees. is set. When the positional deviation dx exceeds the third predetermined value, the upper limit of the correction value of the connection angle is set to γ degrees. Similarly, the correspondence relationship shown in FIG. 6 may be stored for the angular deviation dθ, or the upper limit values may be stored in association with the ranges of both the positional deviation dx and the angular deviation dθ. .

FIG. 7 is a graph showing the time transition of the deviation (position) of the position of the automatic guided vehicle V from the line L. In FIG. In FIG. 7, the solid line indicates the transition of the deviation d when the upper limit is set according to the procedure shown in the flowchart of FIG. 5, and the dashed line indicates the transition of the positional deviation dx when the upper limit is not set. As shown in FIG. 7, the positional deviation dx between the towed vehicle T and the line L tends to converge by the control with the upper limit set shown in the flowchart of FIG.

As a result of the above-described processing, the position of the drive wheel 222 of the automatic guided vehicle V becomes smaller over time, and is on the line L, as shown in FIG. As a result, the greater the deviation between the position of the driving wheel 222 of the automatic guided vehicle V and the line L, the greater the connection angle, and the faster the return to the line L, the connection angle is bent to the limit, and the return angle is increased. is also increased to avoid a state in which the connection angle does not converge.

FIG. 8 shows a schematic diagram of travel control by the coupling device 1. As shown in FIG. FIG. 8 shows how the unmanned guided vehicle V coupled with the towed vehicle T is retreated along the curved line L. As shown in FIG. In FIG. 8, it shows a state of sequentially moving clockwise from the top. In the state of FIG. 8A, the control unit 100 of the coupling device 1 calculates a reference angle for traveling along the curved line L. As shown in FIG. For example, the control unit 100 sets a reference angle for updating a predetermined R curve. In the state of FIG. 8B, the control unit 100 creates the connection angle θ with the reference angle as the target. In the state of FIG. 8B, a relatively large connection angle θ is created. Since the positional deviation dx between the towed vehicle T and the line L is relatively large, even if the connection angle θ is large, it is allowed. The control unit 100 of the coupling device 1 controls the drive wheels 222 to move backward so that the coupling angle θ is maintained within the allowable range. In the state of FIG. 8C, the control unit 100 has a small positional deviation dx, and while the control unit 100 returns the angle to a small value, it further reduces the angle in the state of FIG. 8D. As a result, the towed vehicle T rides on the curved line L and moves backward.

(Second embodiment)
In the second embodiment, the calculation of the target coupling angle in S105 in the backward control by the coupling device 1 is executed with higher accuracy. FIG. 9 is a block diagram showing configurations of the automatic guided vehicle V and the coupling device 1 of the second embodiment. The configurations of the automatic guided vehicle V, the coupling device 1, and the towed vehicle T of the second embodiment are as follows, except for using the dimensional data (geometric data) shown below and the detailed procedure for calculating the target coupling angle. The configuration is the same as that of the first embodiment. Therefore, common configurations are denoted by the same reference numerals, and detailed description thereof is omitted.

In the second embodiment, the coupling device 1 is provided with an acquisition unit 14 for acquiring the identification data of the vehicle T to be towed. The acquisition unit 14 is an image capturing unit that captures an image behind the automatic guided vehicle V in the traveling direction, and may acquire identification data from a two-dimensional code, barcode, or the like attached to the towed vehicle T. Alternatively, the identification data may be acquired from a tag attached to the towed vehicle T by short-range radio such as RFID.

In the second embodiment, as shown in FIG. 9, in order to calculate the target coupling angle, the dimension data of the automated guided vehicle V and the identification data of the towed vehicle T are stored in the memory 102 in correspondence with the dimension data. Dimensional data including FIG. 10 is a schematic diagram of dimension data. The dimensional data of the automatic guided vehicle V is the width of the rear wheel 222 with reference to the center point Q of the line segment VL connecting the axial centers of the left and right rear wheels 222 which are the drive wheels when the automatic guided vehicle V is viewed from above. W1, including length L1 from center point Q to center point P of connecting shaft 231; The dimensional data of the towed vehicle T is obtained by using the center point R of the line segment TL connecting the shaft centers of the rear wheels when towing in the same manner as the standard, and the width W2 of the rear wheels, the center point R, and the coupling device 1. It includes the length L2 to the center point P of the connecting shaft 231 of the connecting member 23 of the automatic guided vehicle V when connected through the .

Control processing by the coupling device 1 using the dimension data will be described. FIG. 11 is a diagram showing a running example of the automatic guided vehicle V in the second embodiment. As shown in FIG. 11, the automatic guided vehicle V automatically travels along a ring-shaped specific color line L marked on the floor surface. An unmanned guided vehicle V coupled with a towed vehicle T travels along a line L to a specific area B of a destination. A specific area B is an area where the towed vehicle T is parked near the site where the goods loaded on the towed vehicle T are needed. The specific area B, as shown in FIG. 11, is a parking space separated by lines of a specific color, pattern, luster, or the like. When the unmanned guided vehicle V and the coupling device 1 arrive at a specific point near the specific area B, the driving wheel 222 and the coupling device 1 are adjusted so that the towed vehicle T is pushed backward to accommodate the towed vehicle T in the parking space. to control. When it is confirmed that the vehicle T to be towed is in the parking space, the automatic guided vehicle V and the coupling device 1 release the connection with the vehicle T to be towed, move forward toward the line L, and return to the line L. The patrol on line L is resumed.

In the running example shown in FIG. 11, refer to the flow chart for the processing procedure when controlling the drive wheels 222 and the coupling angle so as to push the towed vehicle T in reverse to accommodate the towed vehicle T in the parking space. explain.

FIG. 12 is a flowchart showing an example of control processing procedures by the control unit 100 of the coupling device 1 of the second embodiment. The coupling device 1 is attached to the automatic guided vehicle V and connected to the vehicle T to be towed. Run.

The control unit 100 of the coupling device 1 determines whether or not a backward instruction has been received from the control unit 200 of the automatic guided vehicle V by the processing of the processor 101 (step S201). In step S201, the control unit 200 of the automatic guided vehicle V stops when it reaches a specific point near a specific area B on the route shown in FIG. A retreat instruction is transmitted to the control unit 100 of the coupling device 1 so as to push it into.

If it is determined that the reverse command has not been received (S201: NO), the control unit 100 returns the process to step S201 and waits until it determines that the reverse command has been received. If the control unit 100 determines that it has received the backward instruction (S201: YES), it acquires the right to control the rear wheel drive unit 220 of the rear wheels 222 from the automatic guided vehicle V (step S202). Thereafter, until the control right is relinquished, the rear wheel 222 is controlled by the control signal from the control unit 100, and the towed vehicle T and the coupling device 1 are forward, and the automatic guided vehicle V moves.

The control unit 100 acquires the identification data of the towed vehicle T by the acquisition unit 14 (step S203), and reads the dimension data associated with the acquired identification data from the memory 102 (step S204). In step S<b>203 , the control unit 100 may acquire identification data from the towed vehicle T by the acquiring unit 14 when the towed vehicle T is coupled.

The control unit 100 uses the dimension data to derive a target coupling angle for pushing the towed vehicle T (step S205). Details of the derivation method in step S205 will be described later.

The control unit 100 acquires the actual coupling angle between the coupling device 1 and the automatic guided vehicle V from the encoder 112 (step S206). In step S206, the control unit 100 may use not only the encoder 112 but also a TOF sensor, as will be described later.

The control unit 100 calculates the left-right speed (rotation amount) of the rear wheel 222 so that the actual connection angle becomes the target connection angle (step S207), and outputs a control signal to create the connection angle at the calculated speed. (step S208).

The control unit 100 estimates the positions of the automatic guided vehicle V and the towed vehicle T based on the speed of the driving wheels 222 and the elapsed time from the start of pushing the towed vehicle T (step S209), and the towed vehicle T reaches the target position. is reached (step S210).

When it is determined that the towed vehicle T has reached the target position (S210: YES), the control unit 100 outputs a control signal to the rear wheel drive unit 220 to stop (step S211). The control unit 100 returns the control right of the rear wheel drive unit 220 to the automatic guided vehicle V (step S212), and ends the reverse control.

If it is determined that the towed vehicle T has not reached the target position (S210: NO), the control unit 100 returns the process to step 206.

The processing procedure shown in the flowchart of FIG. 12 will be described in more detail. FIG. 13 is a diagram showing an example of the determined target trajectory. The reference R of the towed vehicle T and the reference point R', which is the target position, are connected by a trajectory including a 90-degree arc RR'' as shown in FIG. Identify the radius r2 and the center point O. Based on the dimension data corresponding to the towed vehicle T towed by the automatic guided vehicle V, the control unit 100 determines the center of TL connecting the shaft centers of the rear wheels of the towed vehicle T. The control unit 100 reads out the length L2 between the reference point R, which is a point, and the center point P of the connecting shaft 231. The control unit 100 reads the length L1 between the reference point Q in the automatic guided vehicle V and the center point P of the connecting shaft 231. .

FIG. 14 is a diagram showing an example of control of the connection angle. FIG. 14 shows the reference point Q of the automatic guided vehicle V for deriving the connection angle necessary for the reference point R of the towed vehicle T to draw the target trajectory (arc RR″) shown in FIG. The geometric data of the center point P of the axis 231 and the connection angle θ are illustrated.

A line segment VL connecting the rear wheels 222 which are driving wheels of the automatic guided vehicle V and its length (width) W1, a line segment TL connecting the fixed shaft (rear wheels) of the towed vehicle T and its length (width) W2 , lengths L1 and L2, and the connection angle θ have the relationship shown in FIG. When the automatic guided vehicle V is moved backward while being connected to the towed vehicle T so as to keep the connection angle θ constant, the automatic guided vehicle V is positioned at the line between the extension of the line segment VL and the extension line of the line segment TL. It rotates about the intersection point O with a radius r1 to the reference point Q. As shown in FIG. Similarly, when the automatic guided vehicle V is retracted while being connected to the towed vehicle T so as to keep the connection angle θ constant, the towed vehicle T moves the distance from the intersection O to the reference point R. is rotated with radius r2.

By being able to specify the geometrical relationship shown in FIG. 14, the connection angle θ can be calculated based on the dimension data such as the length L2 of the towed vehicle T, or conversely, when the connection angle θ can be specified. , the trajectory (radius r2 and center point O) of the reference point R of the towed vehicle T can be calculated from the connection angle θ.

Based on the specified reference points Q and R, the center point P of the connecting shaft 231, the radius r2 and the center O of the arc of the target trajectory, and the read lengths L1 and L2, the control unit 100 calculates the As shown in the following equations (1) to (3), the connection angle θ is calculated based on the control program 1P.

Angle POR=φ2=arcTAN(L2/r2) (1)
Radius r=r2/COSφ2 (2)
θ=arcSIN(L1/r)+arcSIN(L2/r) (3)

The control unit 100 of the coupling device 1 sets and controls the left and right rotation speeds of the rear wheels 222 of the automatic guided vehicle V so as to maintain the coupling angle θ thus calculated. As a result, the center point P of the connecting shaft 231 moves on a circular orbit with a radius of r with respect to the center point O, the reference point Q of the automatic guided vehicle V moves on a circular orbit with a radius of r1 with respect to the center point O, The reference point R of the towed vehicle T moves with respect to the center point O on a circular orbit with a radius of r2.

16 based on the identified reference points Q and R, the center point P of the connecting shaft 231, the read lengths L1 and L2, and the actual connecting angle θ obtained from the encoder 112. Based on the geometric relationships shown, the trajectory of the towed vehicle T can be derived as follows. First, the control unit 100 sets the intersection of an extension line of VL connecting the centers of the rear wheels 222 of the automatic guided vehicle V and an extension line of a line segment TL connecting the center of the rear wheels of the towed vehicle T to the center O of the arc. and specify. The control unit 100 can derive an arc centered at the intersection point O and having a radius of a distance r2 to the reference point R as the trajectory of the vehicle T to be towed.

As described above, using the geometrical relationship shown in FIG. 14, the trajectory defined by the connection angle θ or the center point O and the radius r2 is calculated based on the length L2 corresponding to the towed vehicle T. can be done.

In addition, the connection device 1 is configured so that the engagement target by the engagement portion 12, that is, the connection angle with the towed vehicle T to be connected to the automatic guided vehicle V is horizontally aligned on the surface of the connection device 1 facing the towed vehicle T. A plurality of provided distance sensors (TOF sensor, etc.) may be used for measurement (S206). In this case, the connection device 1 can geometrically calculate the connection angle from the difference between the distance data measured by the plurality of distance sensors. Further, the coupling device 1 reads identification data for identifying the type and size of the towed vehicle T to be coupled from the tag attached to the towed vehicle T by the acquisition unit 14, and acquires the length L2 data. good too. The tag may be a bar code, a two-dimensional code, or the like when the acquisition unit 14 is an imaging unit. It may be a storage medium from which information such as identification data stored therein can be read.

Under the control of the coupling device 1 of the first embodiment and the second embodiment, the towed vehicle T is prevented from moving backward with the towed vehicle T coupled while avoiding a simple increase in the coupling angle θ. can be controlled to push to the desired position.

1st Embodiment and 2nd Embodiment demonstrated that the control part 100 of the connection apparatus 1 receives the control right of the rear wheel 222 which is a driving wheel from the automatic guided vehicle V, and controls it. However, the above-described reverse control processing procedure may be performed by the control unit 200 of the automatic guided vehicle V itself.

The embodiments disclosed as described above are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the scope of claims, and includes all modifications within the meaning and scope of equivalence to the scope of claims.

1 connecting device 11 connecting part 112 encoder (sensor)
12 Engagement Part 13 Imaging Part 14 Acquisition Part 100 Control Part (Computer)
102 memory (storage unit)
V automatic guided vehicle 200 control unit (computer)
222 rear wheel (drive wheel)
231 connecting shaft T towed vehicle T1 frame T2 wheel

Claims (9)

A control method in which a computer controls the driving wheels of an automatic guided vehicle,
The towed vehicle is connected by a connecting shaft so as to be rotatable left and right with respect to the traveling direction of the automatic guided vehicle,
The computer is
When instructed to retreat,
Acquiring a captured image from an imaging unit that captures the rear of the automatic guided vehicle,
calculating a deviation between the towed vehicle and a target trajectory including a straight line or curve of the towed vehicle based on the captured image;
reading the upper limit value corresponding to the calculated deviation from the upper limit value of the correction value of the connection angle stored in advance in the storage unit according to the magnitude of the deviation;
setting the connection angle of the towed vehicle on the connection shaft within a range not exceeding the upper limit ;
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
A control method for an automatic guided vehicle, wherein the drive wheels are controlled based on the calculated amount of rotation. A control method in which a computer controls the driving wheels of an automatic guided vehicle,
The towed vehicle is connected by a connecting shaft so as to be rotatable left and right with respect to the traveling direction of the automatic guided vehicle,
The computer is
when a backward instruction is received, the connection angle of the towed vehicle on the connection shaft is derived from the following formulas (1) to (3) and set;
Angle POR=φ2=arcTAN(L2/r2) (1)
Radius r=r2/COSφ2 (2)
θ=arcSIN(L1/r)+arcSIN(L2/r) (3)
O: The point where the extension of the rotation axis of the drive wheel of the automatic guided vehicle and the extension of the rotation axis of the drive wheel of the towed vehicle intersect P: The center point of the connecting shaft Q: The rotation axis of the drive wheel of the automatic guided vehicle center point of R: center point of rotation axis of fixed wheel of towed vehicle
L1: Length of line segment PQ
L2: Length of line segment PR
r: Radius of rotation of point P centered on point O
r2: Radius of rotation of point R centered on point O
θ: Connection angle (deviation between the traveling direction of the unmanned guided vehicle and the traveling direction of the towed vehicle)
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
controlling the drive wheels based on the calculated amount of rotation;
A control method for an automated guided vehicle. The computer is
Using a sensor that measures the connection angle at the connection shaft,
3. The automatic guided vehicle control method according to claim 2 , wherein the trajectory of the towed vehicle is derived based on the actual connection angle measured by the sensor and the formulas (1) to (3). The computer is
Dimensional data of the towed vehicle is stored in advance in association with identification data for identifying the towed vehicle,
reading dimensional data corresponding to the identification data of the towed vehicle;
calculating the connection angle using the length L2 included in the dimension data in the formulas (1) to (3);
The method for controlling an automatic guided vehicle according to claim 2 or 3 . The computer is provided in a coupling device that is connected to the rear part of the automatic guided vehicle via the coupling shaft and has an engaging portion that engages with the towed vehicle for coupling.
The method for controlling an automatic guided vehicle according to claim 1 or 2 . A control device comprising a control unit in which a computer controls the driving wheels of an automatic guided vehicle,
The towed vehicle is connected by a connecting shaft so as to be rotatable left and right with respect to the traveling direction of the automatic guided vehicle,
The control unit
When receiving a backward instruction , acquiring a captured image from an imaging unit that captures the rear of the automatic guided vehicle,
calculating a deviation between the towed vehicle and a target trajectory including a straight line or curve of the towed vehicle based on the captured image;
reading the upper limit value corresponding to the calculated deviation from the upper limit value of the correction value of the connection angle stored in advance in the storage unit according to the magnitude of the deviation;
setting the connection angle of the towed vehicle on the connection shaft within a range not exceeding the upper limit ;
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
A control device for an unmanned guided vehicle that controls the driving wheels based on the calculated rotation amount. A control device comprising a control unit in which a computer controls the driving wheels of an automatic guided vehicle,
The towed vehicle is connected by a connecting shaft so as to be rotatable left and right with respect to the traveling direction of the automatic guided vehicle ,
The control unit
when a backward instruction is received, the connection angle of the towed vehicle on the connection shaft is derived from the following formulas (1) to (3) and set;
Angle POR=φ2=arcTAN(L2/r2) (1)
Radius r=r2/COSφ2 (2)
θ=arcSIN(L1/r)+arcSIN(L2/r) (3)
O: The extension of the rotation axis of the driving wheel of the automatic guided vehicle and the extension of the rotation axis of the driving wheel of the towed vehicle
point of intersection
P: Center point of connecting axis
Q: The center point of the rotation axis of the driving wheel of the automatic guided vehicle
R: Center point of the rotation axis of the fixed wheel of the towed vehicle
L1: Length of line segment PQ
L2: Length of line segment PR
r: Radius of rotation of point P centered on point O
r2: Radius of rotation of point R centered on point O
θ: Connection angle (deviation between the traveling direction of the unmanned guided vehicle and the traveling direction of the towed vehicle)
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
controlling the drive wheels based on the calculated amount of rotation;
Control device for automated guided vehicles. A computer program that causes a computer that controls driving wheels of an automatic guided vehicle to execute control processing in a state in which the towed vehicle is rotatably connected to the towed vehicle by a connecting shaft to the left and right with respect to the traveling direction,
to the computer;
When instructed to retreat,
Acquiring a captured image from an imaging unit that captures the rear of the automatic guided vehicle,
calculating a deviation between the towed vehicle and a target trajectory including a straight line or curve of the towed vehicle based on the captured image;
reading the upper limit value corresponding to the calculated deviation from the upper limit value of the correction value of the connection angle stored in advance in the storage unit according to the magnitude of the deviation;
setting the connection angle of the towed vehicle on the connection shaft within a range not exceeding the upper limit ;
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
A computer program for executing a process of outputting a control signal for controlling the driving wheels based on the calculated amount of rotation. A computer program that causes a computer that controls driving wheels of an automatic guided vehicle to execute control processing in a state in which the towed vehicle is rotatably connected to the towed vehicle by a connecting shaft to the left and right with respect to the traveling direction,
to the computer;
when a backward instruction is received, the connection angle of the towed vehicle on the connection shaft is derived from the following formulas (1) to (3) and set;
Angle POR=φ2=arcTAN(L2/r2) (1)
Radius r=r2/COSφ2 (2)
θ=arcSIN(L1/r)+arcSIN(L2/r) (3)
O: The extension of the rotation axis of the driving wheel of the automatic guided vehicle and the extension of the rotation axis of the driving wheel of the towed vehicle
point of intersection
P: Center point of connecting axis
Q: The center point of the rotation axis of the driving wheel of the automatic guided vehicle
R: Center point of the rotation axis of the fixed wheel of the towed vehicle
L1: Length of line segment PQ
L2: Length of line segment PR
r: Radius of rotation of point P centered on point O
r2: Radius of rotation of point R centered on point O
θ: Connection angle (deviation between the traveling direction of the unmanned guided vehicle and the traveling direction of the towed vehicle)
calculating the amount of left and right rotation of the drive wheels for moving the automatic guided vehicle backward based on the set connection angle;
controlling the drive wheels based on the calculated amount of rotation;
A computer program that causes a process to be performed.

Images