JP4427360B2 - Method and device for guiding entry of automatic guided vehicle into pallet - Google Patents

Description

  The present invention relates to a method and an apparatus for guiding an approach to a pallet of an automatic guided vehicle capable of loading and transporting a pallet having both legs on which heavy objects are placed on a premises such as a steelworks.

  At steelworks, heavy objects such as coils and large steel materials are placed on a pallet with legs, the loading platform is lowered and submerged between both legs of the pallet. The transport vehicle is already widely used.

  This transport vehicle has a flat loading platform over its entire length, has a number of wheels, each wheel is steerable, is attached to the frame via an arm, and changes the height of the loading platform by rotating the arm It is configured as follows.

  In recent years, there has been a demand for unmanned operation of transport vehicles from the viewpoint of further streamlining logistics in steelworks. By the way, the pallet on which this heavy object is placed has a considerably long length (loading direction), and the distance between both legs is not so large as the width of the loading platform of the conveying vehicle. In order to allow the unmanned transport vehicle to smoothly enter the predetermined position between the legs of the pallet, the center line of the automated guided vehicle in the longitudinal direction of the pallet is aligned with the center line of the longitudinal direction of the pallet in front of the pallet. It is necessary to keep.

  As means for this, for example, a ground guide such as magnetic tape is provided on the approach path to the pallet, and each wheel is steered while detecting this by a ground guide sensor mounted on the front and rear of the automatic guided vehicle, It is effective to correct the deviation from the ground guide. However, according to this method, the pallet must be accurately placed on the ground guide, and since the ground guide is outdoors, the ground guide is likely to become dirty or damaged. In addition, when changing the placement location of the pallet, a ground guide must be newly added, and the route cannot be easily changed due to the high cost of burial. Furthermore, the ground guide sensor mounted on the automatic guided vehicle must always be held at a constant distance from the ground guide. However, there is a problem that the mounting of the ground guide sensor is complicated because the loading platform moves up and down.

In order to solve this problem, in Patent Document 1, a laser sensor is provided at the center of the front end of the automatic guided vehicle, and the distance to the pallet leg is detected by scanning the laser beam in an arc shape in the left-right direction. A method is shown in which the approach direction is determined by calculating the approach direction while sensing the gap to the leg. However, in this method, it is necessary to put an iron plate on one side of the pallet leg for the convenience of the calculation method, and there is a problem that extra weight is added or the adjacent pallet enters the blind spot and cannot be detected. In addition, the cost for attaching iron plates to a large number of pallets is necessary, which increases the cost.
JP 2002-182744 A

  The present invention makes it possible to adopt a pallet that does not have an iron plate on both legs as a pallet for an automatic guided vehicle, so that a predetermined pallet can be freely selected from a plurality of arranged pallets and transported inexpensively and safely. It is an object to develop a vehicle guidance method and apparatus.

  In general, both legs of the pallet have a ramen or truss structure, and the adjacent pallet can be seen through between them, and if the iron plate is not stretched, the adjacent pallet will not become a blind spot. Further, the ramen or truss structure of both legs of the pallet ensures sufficient strength, and the strength does not become insufficient even if an iron plate is not stretched on the side surface. Therefore, from these facts, the iron plates stretched on both legs have never been in operation. In addition, since both legs of the pallet have a ramen or truss structure, an oblique member to which the vertical load of the legs is applied is defined as a leg column.

The present invention has been made on the basis of the above findings, and the gist of the present invention is as follows.
(1) An automatic guided vehicle that moves down and enters a cargo bed between both legs of a pallet having both legs made of a steel frame ramen or truss structure and carries the pallet by raising the cargo bed on the premises of the steelworks. In the method of guiding entry to the pallet,
Calculate the right leg target area where the right leg is estimated to exist and the left leg target area where the left leg is estimated to exist using map information and travel distance data of the travel route and pallet stored in advance,
The distance and direction from the automated guided vehicle to the pallet leg column are detected by the distance measuring means, and the right limb column is measured from the detected limb point and the calculated right and left leg target areas. Extract points and left pedestal measurement points,
From the measurement points of the right leg column and the left leg column, calculate the position of the inner method of the pillars of both legs,
Calculate the direction of both legs of the pallet from the internal position of the pillars of both legs,
Calculate the pallet center line from the direction of both legs,
While detecting the gap and travel distance between the automatic guided vehicle and the pallet, and
A method for guiding the entry of an automatic guided vehicle into a pallet, wherein the guide is guided so that a center line of the pallet and a center line of the automatic guided vehicle coincide with each other.
(2) An automated guided vehicle that moves down a cargo bed between both legs of a pallet having both legs made of a shaped steel ramen or truss structure and carries the pallet by raising the cargo bed on the premises of an ironworks. In the pallet entry guidance device,
A detector with a laser beam that is installed at the center of the tip of the automated guided vehicle and detects the distance and direction to the pillar of the leg of the pallet;
Calculate the right leg target area where the right leg is estimated to exist and the left leg target area where the left leg is estimated to exist using map information and travel distance data of the travel route and pallet stored in advance,
From the detected pedestal point and the calculated right leg target area and left leg target area, the measurement point of the right limbal column and the measurement point of the left limbal column are extracted,
An arithmetic unit that calculates a pallet center line from the measurement position of the right leg column and the left leg column, the position of the inner column of both legs, the direction of both legs of the pallet, and the direction of both legs;
A side sensor for detecting a gap between the pallet provided on the side surface of the automatic guided vehicle and the automatic guided vehicle;
A travel distance sensor for detecting a travel distance provided in the automatic guided vehicle;
A guide device for entering a pallet of an automatic guided vehicle, comprising: a guide device that guides the center line of the pallet and a center line of the automatic guided vehicle to coincide with each other.

  According to the present invention, there is no need to stretch iron plates on both legs of the pallet for detection, and the pallet can be saved by unnecessary weight. In addition, there is no pallet that becomes a blind spot when entering a predetermined pallet in a situation where a plurality of pallets are placed, so that the pallet can carry any pallet as long as it can be entered. became. Therefore, the cost of remodeling the pallet by placing an iron plate can be omitted, and the unmanned transport vehicle can be made cheap and safe.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a perspective view showing an external configuration of the automatic guided vehicle and the pallet according to the embodiment of the present invention. The automatic guided vehicle 10 has a flat loading platform 1 over its entire length, and includes a plurality of wheels 2. Each wheel 2 is attached to the frame by an arm, and the height of the loading platform 1 is changed by rotating the arm. It is configured to be able to. Each wheel has a configuration that can be steered. The automatic guided vehicle 10 can travel at the same speed for both forward and backward travel.

  An approach sensor 11 for detecting and guiding the pallet 20 is provided at the front and rear portions on the center line of the body frame. As the approach sensor 11, an optical scanner including a projector that emits laser light, a light receiver that receives the reflected light, and a motor that rotates the light projector and the light receiver so as to draw a circular arc horizontally is used. Note that the front sensor in the traveling direction of the automatic guided vehicle 10 is used as the approach sensor 11, and at this time, the rear sensor is turned off.

  In addition, a plurality of side sensors 15 for detecting the distance between the inner side surfaces of the column portions 20 a and 20 b of both legs of the pallet 20 are provided on both side ends of the loading platform 1. This side sensor 15 uses an ultrasonic sensor here. The wheel 2 is provided with a generator-type travel distance sensor 16 (not shown) for detecting the travel distance.

  The signals from the approach sensor 11, the side sensor 15, and the travel distance sensor 16 are taken into a control device mounted on the automatic guided vehicle 10 and are output to a steering control unit that operates and operates the steering device. 3 is provided in order to enable the driver to drive when the travel control system of the automatic guided vehicle 10 fails in the driver's cab or when it is not suitable for automatic transfer.

  The pallet 20 is integrally formed with both legs on both sides of the lower part of the gantry 21 on which heavy objects are placed. Both of these legs are generally made of a steel frame with a ramen structure or a truss structure, and diagonal members constitute the column portions 20a and 20b. Next, when the pallet 20 on which a heavy object is placed is loaded on the loading platform 1 and transported by the automatic guided vehicle 10 configured as described above, the automatic guided vehicle 10 is automatically guided to enter the pallet 20. The apparatus will be described.

  FIG. 1 is a block diagram illustrating a configuration of a control device 30 of the automatic guided vehicle 10 according to the present embodiment. The control device 30 includes an input unit 31, an arithmetic processing unit 32, a storage unit 33, and a steering control unit 35.

  The input unit 31 takes in signals from the approach sensor 11, the side sensor 15, and the travel distance sensor 16, converts them into signals that can be easily processed by the arithmetic processing unit 32, and outputs them. The arithmetic processing unit 32 performs arithmetic processing from the information in the input unit 31 and the information in the storage unit 33 and outputs it to the steering control unit 35.

  In addition to storing the result of the arithmetic processing unit 32 and information on the travel distance, the storage unit 33 includes a setting unit for setting a reference value necessary for the arithmetic processing in advance. For example, setting of a range (distance in the width direction and depth direction) for filtering data when the pallet position is detected by the approach sensor 11 is performed.

  Next, the operation when the above-described automatic guided vehicle 10 enters the pallet 20 will be described with reference to the flowchart shown in FIG. First, the automatic guided vehicle 10 is separately equipped with an autonomous traveling control device 36 (internal structure is not shown) for traveling along the traveling route, and guidance to the vicinity of the pallet 20 is thereby performed. (Step 100).

  The autonomous traveling control device 36 stores the map information of the traveling route, measures the current position based on the current position recognizing device using the traveling distance sensor 16 and the gyroscope 17, and the route set by the automatic guided vehicle in advance. It will guide you to run. When the automatic guided vehicle 10 autonomously travels and comes near a predetermined position (position determined by the autonomous traveling control device) defined in front of the pallet 20, it is determined whether or not it is a predetermined position (step 110), If it is within a certain range, the vehicle stops (step 120). Then, the autonomous traveling control device is turned OFF, the loading platform is lowered, and the guidance of the automatic guided vehicle 10 is switched to the control by the control device 30 for guiding the entry into the pallet.

  Next, the pallet 20 is detected by the approach sensor 11 at step 130. As shown in FIG. 3, the detection is performed by scanning the laser beam at a constant interval (for example, 0.5 degrees in the figure) from the right side to the left side of the automatic guided vehicle 10 at the center c of the approach sensor 11. To the shape steel members constituting the column portions 20a, 20b of both legs of the pallet 20, and sent to the arithmetic processing unit 32. Further, since the steel plates are not installed on the side surfaces of both legs, the positions of the shape steels constituting the column portions 20a 'and 20b' of both legs of the pallet 20 'adjacent to each other can be detected from the gap between the shape steels.

  The arithmetic processing unit 32 extracts the position of the inner leg method from the shape data of the leg pillars 20a and 20b from the center c by calculation, and calculates the inner leg method of the pallet from the coordinates of the obtained inner point and the midpoint coordinates thereof. (Lines L1, L2) and a center line (Line Lc) are obtained. Then, the inclination θ of the straight line Lc with the center c as the coordinate center, the distance x from the center c to the center line Lc, the distance y to the pallet, and the interval W between the straight lines L1 and L2 are calculated. (Step 140).

  In step 150, the calculated values (θ, x, W) are compared with the allowable angle and allowable distance stored in advance in the storage unit 33. If the calculated value (θ, x, W) is within the allowable range, the approach state is determined to be normal. Go to 160. If any value is outside the allowable range, it is determined that the approach state is abnormal, an alarm is output, and the subsequent processing is stopped (step 170).

  In step 160, the steering control unit 35 is commanded so that θ and x become zero. This control is sequentially performed while the automatic guided vehicle 10 is traveling at a low speed.

  The automatic guided vehicle 10 is guided so that its center line coincides with the center line of the pallet 20 and enters the pallet 20. When the automatic guided vehicle 10 enters the pallet 20 to some extent, and the side sensor 15 detects the shape steel slopes of the pillars 20a and 20b of the legs of the pallet 20 (step 180), the operation of the approach sensor 11 is stopped, Switching to guidance based on the detection signal of the side sensor 15 is performed.

  The automatic guided vehicle 10 is steering-controlled so that the left and right detection signals of the side sensor 15 are substantially equal, that is, the automatic guided vehicle 10 travels in the center of the pallet 20 (step 190). The vehicle stops after traveling a predetermined distance (step 200). Thus, the approach guidance control of the automatic guided vehicle 10 to the pallet 20 is completed.

  Next, after the loading platform 1 of the automatic guided vehicle 10 is raised and the pallet 20 is carried, the automatic traveling control device is switched. And it is conveyed to the destination by autonomous traveling. When the vehicle arrives at the destination, the automatic guided vehicle 10 is stopped, the loading platform 1 is lowered, the pallet 20 is lowered, the detection by the side sensor 15 is performed, and the pallet 20 is retreated.

  The calculation process in step 140 in the flowchart shown in FIG. 4 will be described with reference to the flowchart shown in FIG. Information detected by the approach sensor 11 and sent to the arithmetic processing unit 32 is generally in a polar coordinate format with the center c of the approach sensor 11 as the origin (step 300).

  In step 310, a right leg target area 60 in which the right leg 20a of the pallet 20 as shown in FIG. 7 is assumed to exist and a left leg target area 61 in which the left leg 20b is assumed to be present are calculated. In the calculation of the target area, the map information stored in advance in the storage unit 33 and the travel distance data (or the distance y with the previously calculated pallet) are used to determine the area as the automatic guided vehicle approaches the pallet. By making it approach or reduce, unnecessary detection data such as fences and buildings installed around the pallet can be excluded from the subsequent calculations.

  Next, polar coordinate data is coordinate-transformed into an orthogonal coordinate system having the center c of the approach sensor 11 as the origin (step 320). At this time, θ1 to θ4, Rmax = Max (R2, R3), Rmin = Min (R1, R4) in FIG. 7 are set in the previous step 310, and data coordinates (R (k), θ (k)) are set. As compared with the above, if only the data satisfying the predetermined condition is set as a subsequent calculation target, the calculation amount can be reduced. (For example, data satisfying θ2 <θ (k) <θ3, R (k) <Rmin, or Rmax <R (k) does not perform orthogonal coordinate conversion, and does not use for subsequent calculations. Will not give.)

  In step 330, it is determined whether or not the measurement point coordinates (x (k), y (k)) of the leg column part obtained by the orthogonal coordinate transformation are within the above-mentioned left and right leg target areas, and these are determined in the right leg column part. The measurement points {A (i); i = 1 to Na} and the measurement points {B (j); j = 1 to Nb} of the left pedestal are determined.

Then, the inner method of both the left and right legs is determined as follows.
The distance between the points is calculated for all combinations of the measurement points of the left and right pedestal parts, and the number of the measurement point of the left pedestal part that is the shortest distance from the measurement point A (i) of the right pedestal part is P (i). Then, the number of the measurement point of the right leg column portion that is the shortest distance from the measurement point B (j) of the left leg column portion is obtained as Q (j) (step 340).
Next, it is determined whether the equation i = Q (P (i)) is established for the measurement point numbers i = 1 to Na of the right leg column. (Step 350),
If established, the points A (i) and B (P (i)) are extracted as opposing pairs, and are determined as the inner leg position of the right leg and the inner leg position of the left leg, respectively. At this time, the measurement points of the leg pillars form a group as shown in detail in FIG. These measurement point groups are divided into 51, 52, and 53 data groups based on the relationship between the direction of the approach sensor and the shape 50 of the shape steel. Among these, when the approach sensor of the automatic guided vehicle is located inside the normal line in both legs of the pallet, since there are measurement points facing as a pair for the data group 51, it is extracted as data corresponding to the internal method, The other data groups 52 and 53 do not have a paired point and are not extracted as the internal position. On the other hand, in the case where the approach sensor of the automatic guided vehicle is located outside the normal line of both legs of the pallet, the data group 53 is set as the internal law position by the above logic for the column part of the near leg, and the leg on the far side. It is extracted together with a part of the data group 51 of the column part. (Step 360).
At the same time, various coefficients (for example, the midpoint of the obtained pair of left and right internal normal points, the sum of the x and y coordinates, and the sum of squares) necessary for approximation of the normals in both legs and the pallet center line are calculated. (Step 370).
Note that the arithmetic processing in steps 350 to 370 may be performed in the same manner with respect to the measurement point numbers j = 1 to Nb of the left pedestal column.
Then, using the quantity of the extracted points and the calculated point coordinates and various coefficients, the normal lines on both legs of the pallet (straight lines L1, L2) and the center line (straight line Lc) are obtained (step 380).

  If these steps are performed in the reverse order, it can be applied even when the pallet is detached. Therefore, even when the automatic guided vehicle is detached from the pallet, the automatic guided vehicle can be unmanned inexpensively and safely.

It is a block diagram which shows the structure of the automatic guided vehicle 10 and the control apparatus 30 by this embodiment. It is a perspective view which shows the external appearance structure of the automatic guided vehicle and a pallet. It is explanatory drawing of an effect | action of the approach sensor 11. FIG. It is a flowchart of the pallet approach guidance of the automatic guided vehicle. It is the flowchart of the normal position detection and centerline calculation process in the pallet. 4 is an explanatory diagram showing an example of data (points) detected by the approach sensor 11. FIG. It is explanatory drawing of the both-legs target area set by the same calculation processing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carriage 2 Traveling wheel 3 Driver's cab 10 Automatic guided vehicle 11 Approach sensor 15 Side sensor 16 Traveling distance sensor 17 Gyroscope 20, 20 'Pallet 20a, 20b, 20a', 20b 'Leg column part 21 Base 30 Controller 31 Input Unit 32 Arithmetic processing unit 33 Storage unit 35 Steering control unit 36 Autonomous control device 50 Shaped steel (section) which is a pillar of leg
51 Flange part (inner method) data group 52 Web part data group 53 Flange part (outer method) data group 60 Right leg target area 61 Left leg target area

Claims (2)

To the pallet of an automated guided vehicle that transports a pallet that is carried by lowering the cargo bed between the legs of a pallet having both legs made of shaped steel ramen or truss structure on the premises of the steelworks. In the approach guidance method of
Calculate the right leg target area where the right leg is estimated to exist and the left leg target area where the left leg is estimated to exist using map information and travel distance data of the travel route and pallet stored in advance,
The distance and direction from the automated guided vehicle to the pallet leg column are detected by the distance measuring means, and the right limb column is measured from the detected limb point and the calculated right and left leg target areas. Extract points and left pedestal measurement points,
From the measurement points of the right leg column and the left leg column, calculate the position of the inner method of the pillars of both legs,
Calculate the direction of both legs of the pallet from the internal position of the pillars of both legs,
Calculate the pallet center line from the direction of both legs,
While detecting the gap and travel distance between the automatic guided vehicle and the pallet, and
A method for guiding the entry of an automatic guided vehicle into a pallet, wherein the guide is guided so that a center line of the pallet and a center line of the automatic guided vehicle coincide with each other. To the pallet of an automated guided vehicle that transports a pallet that is carried by lowering the cargo bed between the legs of a pallet having both legs made of shaped steel ramen or truss structure on the premises of the steelworks. In the approach guidance device of
A detector with a laser beam that is installed at the center of the tip of the automated guided vehicle and detects the distance and direction to the pillar of the leg of the pallet;
Calculate the right leg target area where the right leg is estimated to exist and the left leg target area where the left leg is estimated to exist using map information and travel distance data of the travel route and pallet stored in advance,
From the detected pedestal point and the calculated right leg target area and left leg target area, the measurement point of the right limbal column and the measurement point of the left limbal column are extracted,
An arithmetic unit that calculates a pallet center line from the measurement position of the right leg column and the left leg column, the position of the inner column of both legs, the direction of both legs of the pallet, and the direction of both legs;
A side sensor for detecting a gap between the pallet provided on the side surface of the automatic guided vehicle and the automatic guided vehicle;
A travel distance sensor for detecting a travel distance provided in the automatic guided vehicle;
A guide device for entering a pallet of an automatic guided vehicle, comprising: a guide device that guides the center line of the pallet and a center line of the automatic guided vehicle to coincide with each other.

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