JP2011020848A - Moving body, transportation system, and transporting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the interference between moving bodies moving in a two-dimensional or a three-dimensional space by performing a simple processing. <P>SOLUTION: This transportation system includes: a plurality of moving bodies 2 for transportation capable of moving in the two-dimensional directions; a locus computing means 16 for computing an estimated locus of the moving body 2 per moving body 2: a locus acquisition means for acquiring an estimated locus, on which other moving body 2 moves; a determining means for determining existence of an overlap of the loci between the moving bodies 2 independently of the transit time at a point wherein the loci overlap with each other; and a bypass computing means 16 for computing a bypass so as to go around by the point, wherein the loci overlap with each other, when a determination that the loci overlap with each other is done. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mobile body that autonomously avoids interference and a system using the mobile body.

  Patent Document 1 (JP2005-301364A) discloses that interference between moving bodies is avoided by notifying the positions of the moving bodies. In Patent Document 1, the moving body travels substantially on a one-dimensional traveling path, and a traveling space having two or more degrees of freedom is not examined.

  The inventor studied avoidance of interference in a traveling space having two or more degrees of freedom. For example, in the automatic warehouse shown in FIGS. 2 and 3, for example, two stacker cranes 2 travel on different traveling rails 31, and the lifting platform 28 may interfere with each other. In the flat warehouse shown in FIG. 4, a plurality of moving bodies 42 travel in a traveling space 40 on a plane. 2 to 4, in order to avoid interference between moving bodies, for example, each moving body exchanges data of travel position and passage time with respect to each position of the travel route and does not travel at the same position at the same time. What should I do? However, this requires position and time data, which increases the amount of data, and there is a risk of interference if the vehicle cannot travel as planned.

JP2005-301364A

  An object of the present invention is to prevent interference between moving bodies moving in a two-dimensional or three-dimensional space with a simple process.

The present invention is a movable body that is movable in at least a two-dimensional direction,
A trajectory calculating means for calculating a trajectory on which the moving object is scheduled to move;
A trajectory grasping means for grasping a trajectory that another moving body is scheduled to move;
A determination means for determining whether or not the trajectory of another moving body overlaps with the planned trajectory of the self, ignoring the passage time of the place where the trajectory overlaps,
And a detour calculation means for calculating a detour that detours a portion where the tracks overlap when it is determined that the tracks overlap.

The present invention further provides a transport method for transporting an article by moving a plurality of movable bodies that are movable in at least a two-dimensional direction,
By the trajectory calculating means, the trajectory that the moving body is scheduled to move is calculated for each moving body,
With the judging means, the presence or absence of the trajectory overlap between moving bodies is ignored, ignoring the passage time of the place where the trajectory overlaps,
When it is determined that the trajectories overlap, the detour calculation unit calculates a detour that bypasses the portion where the trajectories overlap.

Further, the present invention is a transport system including a plurality of transport moving bodies that are movable in at least a two-dimensional direction,
A trajectory calculating means for calculating a trajectory that the moving body is scheduled to move for each moving body;
A determination means for determining whether or not the trajectory overlaps between the moving bodies by ignoring the passage time of the portion where the trajectories overlap;
Provided with a detour calculation means for calculating a detour that bypasses a locus of at least one of the pair of moving bodies with which the locus overlaps when the locus is determined to overlap. It is characterized by that.

  In the present invention, trajectories are calculated in two or more dimensional moving directions, and the presence / absence of trajectory overlap between moving bodies is determined by ignoring the passage time of the location where the trajectories overlap, and detours occur when the trajectories overlap. Since the trajectory is data that does not include the scheduled passage time, it is easier to prevent interference between the moving bodies than when managing the position and time through which the moving body passes. However, the trajectory in which another moving body has already traveled is excluded from the overlap judgment target in principle. It should be noted that the trajectories overlap because the trajectories overlap in each dimension of two or more dimensions, and it is not necessary to calculate a detour even if the trajectories overlap in only one dimension. The trajectory calculation, overlap determination, detour calculation, and the like may be executed by an individual mobile body or may be processed by a controller higher than the mobile body such as a system controller.

  Preferably, the determination means evaluates the degree of overlap higher when at least one moving body is stopped at the position where the trajectories overlap than when both moving bodies are moving at the position where the trajectories overlap. At the same time, the detour calculation unit calculates the detour only when the degree of overlap is equal to or greater than a predetermined value. When both moving bodies are moving at a location where the trajectories overlap, the possibility of interference occurring through the location at the same time is not high. Therefore, in such a case, other moving objects are detected and avoided by a sensor or the like without correcting the trajectory. As a result, it is possible to reduce the calculation of detours and use a simple trajectory without detours.

  Preferably, the sensor that detects the position of another moving body based on its own position, and the two-dimensional path along a path different from the predetermined locus when the position of the other moving body falls within a predetermined range. An avoiding means for avoiding interference with other moving bodies is provided by moving in the direction. By doing so, it is possible to back up avoidance of interference due to calculation of a detour.

  Preferably, before the moving body starts moving, the locus of the moving body is calculated, the overlap is determined, and the detour is calculated. This eliminates the need for processing from calculation of the trajectory to calculation of the detour during movement.

Block diagram of the transport system of the embodiment Front view of automatic warehouse using transport system of embodiment Plan view of the main part of the automatic warehouse in FIG. Plan view of a flat warehouse where a mobile unit of a modified example travels The flowchart which shows the interference avoidance algorithm in an Example The figure which shows typically the locus | trajectory which needs the detour in an Example. The figure which shows typically the locus | trajectory which does not need the detour in an Example. The figure which shows typically the locus | trajectory at the time of detouring in an Example Diagram showing avoidance by different avoidance angles θ1 and θ2. Block diagram of a modified transport system

  In the following, an optimum embodiment for carrying out the present invention will be shown. The scope of the present invention should be determined according to the understanding of those skilled in the art based on the claims, taking into consideration the specification and the well-known techniques in this field.

  1 to 10 show an embodiment and its modifications. FIG. 1 shows a basic embodiment, 1 is a transport system, 2 is a stacker crane of a mobile body, and may be another mobile body such as an automatic guided vehicle. The stacker crane 2 includes a travel drive unit 4 for traveling along the horizontal direction, an elevating drive unit 6 for elevating the elevating table, and a transfer control unit 8 for controlling a transfer device on the elevating table. The lifting platform can move in the two-dimensional direction of the traveling direction and the lifting direction, and interference between the stacker cranes 2 occurs when the position of the lifting platform overlaps the traveling direction in the lifting direction. The stacker crane 2 stores a travel path along the travel direction and the lifting / lowering direction in the layout map storage unit 10.

  Reference numeral 12 denotes a communication unit that communicates with each other between, for example, the stacker cranes 2 and 2, or may communicate with other stacker cranes 2 via a controller 92 on the ground side as shown in FIG. Reference numeral 14 denotes a sensor that monitors the position of another stacker crane 2. In the embodiment, the elevator platform of the stacker crane 2 interferes with each other, so the position of the elevator platform of the other stacker crane is monitored. The type of the sensor 14 is arbitrary, and for example, a photoelectric sensor, an ultrasonic sensor, a laser distance meter, or the like is used.

  The trajectory calculation and detour calculation unit 16 calculates a planned trajectory of the elevator platform in the travel path, and calculates a detour to avoid interference when the calculated trajectory interferes with the trajectories of other stacker cranes. To do. The trajectory is, for example, data of a starting position, a target position, and a row of positions that travel between them, and does not include time. The stacker cranes 2 exchange their trajectories with each other via the communication unit 12, and the detour determination unit 18 determines the necessity of detouring based on whether the trajectory calculated by the calculation unit 16 interferes with the trajectories of other stacker cranes. . When detouring is necessary, the detour is calculated by the calculation unit 16. The trajectory storage unit 20 stores its own planned movement trajectory and the planned movement trajectories of other stacker cranes.

  The avoidance angle storage unit 22 stores a unique avoidance angle θi as a parameter specific to each stacker crane 2, where i is the number of the stacker crane. The avoidance determining unit 24 determines whether avoidance is necessary based on data from the sensor 14 and the like, and whether it can be avoided without stopping. If the avoidance can be avoided without stopping, the avoidance determining unit 24 determines based on the avoidance angle θi. Change the travel route. The parameter for avoidance is not limited to the avoidance angle θi, and may be a parameter used for correcting the miracle. The stop / restart unit 25 performs stop control when stop is necessary to avoid interference and restart after stop. In the restart, the pair of stacker cranes 2 and 2 close to each other is restarted according to a predetermined rule. For example, after one stacker crane operates first and escapes from the interference range, the other stacker crane is also restarted.

  2 and 3 show an automatic warehouse 26 using the stacker crane 2. For example, a pair of stacker cranes 2, 2 run on different running rails 31 a, 31 b, and a lifting platform 28 moves up and down along the mast 27. . Reference numeral 29 denotes an article on the lift 28. If the direction along the traveling rails 31a and 31b is the x direction and the elevating direction is the y direction, interference can occur only in the elevating table 28 when the x direction position of the elevating table is sufficiently close to the y direction position. Interference occurs. 30 is a rack, for example, a pair is provided on the left and right of the traveling rails 31a and 31b, 32 is a station, and 33 is an individual frontage.

  In the flat storage warehouse of FIG. 4, a plurality of automatic guided vehicles 42 corresponding to the stacker crane 2 travel, and the automatic guided vehicle 42 includes a fixed loading platform instead of the lifting platform, and travels two-dimensionally on the traveling space 40. . 44 is a shelf, and there is a passage space 41 between the shelves 44, 44, and no detour can be made in the passage space 41. Therefore, the calculation of the trajectory in the traveling space 40, the determination of the overlap of the trajectory, the calculation of the detour, and the avoidance operation are executed.

  5 to 9 show interference avoidance algorithms in the embodiment. A moving body such as the stacker crane 2 or the automatic guided vehicle 42 calculates a planned movement trajectory before starting traveling, and exchanges them with each other via the communication unit 12. A moving body that is calculating a planned movement trajectory and that has not been sent determines whether or not detouring is necessary using the algorithms shown in FIGS. 6 and 7, reference numerals 60 to 63 denote trajectories, reference numerals 64 to 67 denote departure positions, and reference numerals 68 to 71 denote target positions. As shown in FIG. 6, the trajectory 60 and the trajectory 61 overlap at one place, but when any moving body is traveling at the overlapping position, detouring is unnecessary. On the other hand, as shown in FIG. 7, when the other trajectory passes the stop position on one trajectory, detouring is required. In order to determine whether or not detours are necessary, for example, when moving objects are moving together at locations where trajectories overlap, if the weight is 1, at least one is stopped, the weight is 2, and if the total weight exceeds 1, detour is I need.

  In the embodiment, since the trajectory does not include time, when the traveling trajectories simply overlap, there is a high probability that no interference actually occurs. On the other hand, when the trajectories overlap at the stop position, the stop time is long, so the probability of interference is high. Note that detouring is also required when the trajectory overlaps more than once in a complicated trajectory other than the stop position. Further, the correction of the trajectory by detouring is performed on the side where the trajectory has not been transmitted, and is not performed on the side where the trajectory has been transmitted. Further, the process until the calculation of the detour is completed by the start of movement. In addition, the detour start position is upstream by a predetermined distance in each of the x direction and the y direction from the place where the trajectories overlap. For example, in FIG. 8, reference numeral 80 denotes a trajectory for the first moving body to move from point A to point B, which has already been sent out. Here, if the trajectory 81 is calculated in order for the second moving body to move from the point C to the point D, it intersects at two places, so that it detours like the trajectory 82.

  When the moving body starts moving along the trajectory, for example, the position and speed of another moving body are monitored via the communication unit 12 and the sensor 14. Then, when another moving body approaches to the extent that it needs to be avoided, the moving body avoids as shown in FIG. 9, for example. Here, Q1 and Q2 are a pair of moving bodies, and V1 and V2 are the respective current speeds. Each moving body stores unique avoidance angles θ1 and θ2, and the range of avoidance angles θ1 and θ2 is 0 ° to 360 °. The moving body Q1 changes the target speed to (V1x · cos θ1, V1y · sin θ1) and the moving body Q2 changes the target speed to (V2x · cos θ2, V2y · sin θ2) with respect to the target speed determined from the locus. As a result, the moving bodies Q1 and Q2 move away from the broken-line locus in FIG. 9 and move like a solid line, and although the moved locus crosses once in the middle, the traveling time to the crossing point is significantly different. No interference occurs.

  If the avoidance angle θi is stored, it is possible to avoid the information without knowing how the other party's mobile body is trying to avoid. Such avoidance can also be realized by using a rule such as avoiding clockwise together without using the avoidance angle θi. Interference occurs when the position in the x direction and the position in the y direction overlap, and avoidance is unnecessary in other cases.

  FIG. 10 shows a transfer system 90 that is a modification of FIG. 1, 2 is a moving body such as a stacker crane similar to FIG. Notifies each other of the current position and speed while traveling. In this case, the calculation of the trajectory and the detour, determination of the necessity of detouring, and storage of the trajectory may be performed by the stacker crane 2 or the controller 92.

In the embodiment, the following effects can be obtained.
(1) Since the necessity of detouring is determined from the overlap of scheduled movement trajectories that do not include time, processing is easy.
(2) In determining whether or not a detour is necessary, the weight is changed depending on whether the trajectory overlaps at the traveling position or the trajectory overlaps at the stopped position. As a result, the possibility of interference can be more accurately reflected without using the concept of time.
(3) Avoid according to predetermined rules such as avoidance angle unique to each moving object. For this reason, it is sufficient that the position of the other party's moving body can be recognized by the sensor 14 or the like at least, and the avoidance is simple.
(4) Interference is prevented in three stages: detouring by determining the overlap of the trajectory, avoidance by relative position with other moving objects, and stopping when avoidance cannot prevent interference. For this reason, it is extremely safe.
(5) As described above, interference in a two-dimensional or higher traveling space can be easily and reliably prevented.

DESCRIPTION OF SYMBOLS 1 Transfer system 2 Stacker crane 4 Travel drive part 6 Lift drive part 8 Transfer control part 10 Layout map memory | storage part 12 Communication unit 14 Sensor 16 Trajectory calculation and detour calculation part 18 Detour determination part 20 Trajectory memory | storage part 22 Avoidance angle memory | storage part 24 avoidance determination unit 25 stop / restart unit 26 automatic warehouse 27 mast 28 lifting platform 29 article 30 rack 31a, b traveling rail 32 station 33 frontage 38 flat storage 40 traveling space 41 passage space 42 automatic guided vehicle 44 shelves 60-63 locus 64 to 67 Starting position 68 to 71 Target position 80 to 82 Trajectory 90 Transport system 92 Controller

Claims (6)

A movable body that is movable in at least two dimensions,
A trajectory calculating means for calculating a trajectory on which the moving object is scheduled to move;
A trajectory grasping means for grasping a trajectory that another moving body is scheduled to move;
A determination means for determining whether or not the trajectory of another moving body overlaps with the planned trajectory of the self, ignoring the passage time of the place where the trajectory overlaps,
A moving body comprising: a detour calculation means for calculating a detour that detours a portion where the loci overlap when it is determined that the loci overlap. The determination means evaluates the degree of overlap higher when at least one moving body is stopped at a position where the trajectory overlaps than when both moving bodies are moving at a position where the trajectory overlaps, and
The mobile device according to claim 1, wherein the detour calculation unit calculates the detour only when the degree of overlap is a predetermined value or more. A sensor that detects the position of another moving body based on its own position;
When the position of the other moving body falls within a predetermined range, the avoiding means for avoiding interference with the other moving body by moving in the two-dimensional direction along a path different from the predetermined trajectory. The moving body according to claim 1, wherein the moving body is provided. A transport system including a plurality of transport moving bodies that are movable in at least a two-dimensional direction,
A trajectory calculating means for calculating a trajectory that the moving body is scheduled to move for each moving body;
A determination means for determining whether or not the trajectory overlaps between the moving bodies by ignoring the passage time of the portion where the trajectories overlap;
Provided with a detour calculation means for calculating a detour that bypasses a locus of at least one of the pair of moving bodies with which the locus overlaps when the locus is determined to overlap. A conveyance system characterized by that. A transport method for transporting an article by moving a plurality of movable bodies that are movable in at least a two-dimensional direction,
By the trajectory calculating means, the trajectory that the moving body is scheduled to move is calculated for each moving body,
The determination means determines the presence or absence of trajectory overlap between moving bodies, ignoring the passage time of the location where the trajectory overlaps,
A transport method, characterized in that, when it is determined that the trajectories overlap, the detour calculation unit calculates a detour that bypasses a place where the trajectories overlap.   6. The transport method according to claim 5, wherein the trajectory of the moving body, the determination of the overlap, and the calculation of the detour are performed before the moving body starts moving.

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