JP5910723B2 - Transfer device and control method of transfer device - Google Patents

Description

  The present invention relates to a transfer device and a transfer device control method, and more particularly, to a transfer device that transfers an article to and from a transfer location and a control method of the transfer device.

  A stacker crane provided in a conventional automatic warehouse has a traveling carriage, an elevator mounted on a mast provided in the traveling carriage so as to be movable up and down, and a transfer device provided on the elevator.

  As a transfer device, there is known a transfer device having a clamp portion that can hold both side surfaces of a load and can be extended and contracted (see, for example, Patent Document 1).

  A conventional transfer device has a pair of bases provided on a lifting platform and a pair of arms that advance and retreat individually with respect to the base. Each arm has an intermediate arm portion that advances and retracts relative to the base, and a tip arm portion that advances and retracts relative to the intermediate arm portion. The article is sandwiched between the tip arm portions.

International Publication No. 2011/001472 Pamphlet

In the transfer apparatus of Patent Document 1 that transfers an article while holding an article as described above, the rigidity of the entire arm inevitably decreases in a state where the tip arm portion is advanced. If the rigidity of the entire arm is lowered, when the article is held, the reaction force may cause the width between the tip arm portions to be slightly larger than the width between the bases. . This is because each arm part bends, there is some play for sliding between the base and the arm part, each member is worn or deteriorated by long-term use, etc. Is considered as the cause.
If the arm part is retracted into the base in such a state, the force that the extended tip arm part pinches the article increases, and if this pinching force becomes excessive, the tip arm part bites into the article. May damage the product. If the clamping force is weakened to prevent this, there is a risk of an article transfer error.

  An object of the present invention is to enable an article being transferred to be held with an appropriate force as much as possible in a transfer apparatus that holds and transfers an article with an arm.

Hereinafter, a plurality of modes will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary.
The transfer device according to the present invention is a device for transferring an article to and from a transfer location. The transfer device includes a pair of bases, a pair of arms, a first drive unit, a second drive unit, a reaction force detection unit, and a drive control unit.
The pair of arms are respectively provided on the pair of bases so as to be able to advance and retreat toward the transfer place while sandwiching the article.
The first drive unit drives the pair of bases so as to approach and separate from each other. The second driving unit drives the pair of arms so as to advance and retract from the base.
The reaction force detection unit detects a reaction force from the article when the pair of arms sandwich the article.
The drive control unit can control the first drive unit such that the reaction force detected by the reaction force detection unit is within a predetermined range.
In this transfer device, when the pair of arms is arranged at a position where the article can be sandwiched, the pair of bases are driven by the first drive unit in the direction in which the pair approaches each other. When the pair of arms sandwich the article, the drive control unit controls the first drive unit so that the reaction force detected by the reaction force detection unit falls within a predetermined range. Here, when the pair of arms holds the article, the reaction force is within a predetermined range, so that the article being transferred can be held with an appropriate force as much as possible.

In the transfer apparatus, the reaction force detection unit may include a torque detection unit that detects the torque of the first drive unit as a reaction force. The drive control unit may control the first drive unit based on the torque value detected by the torque detection unit so that the reaction force is within a predetermined range.
Thereby, for example, when the first drive unit electrically drives the pair of bases, the torque can be easily detected from the current value flowing through the first drive unit. Therefore, the reaction force can be easily detected without using a reaction force detection sensor (for example, a sensor such as a pressure sensor or a piezoelectric sensor) at the article clamping portion of the pair of moving arms, and the configuration of the transfer device Can be simplified.
The drive control unit may control the first drive unit so that the reaction force detected by the reaction force detection unit is within a predetermined range when the pair of arms are retracted into the pair of bases.
Thus, the article can be taken into the transfer apparatus while holding the article with a force sufficient to transfer the article and not damaging the article.
The drive control unit can also control the second drive unit, and when the drive control unit retracts the pair of arms into the pair of bases, the reaction force detected by the reaction force detection unit falls within a predetermined range. As described above, the first driving unit and the second driving unit may be controlled.
As a result, the balance between the speed at which the arm is retracted and the speed at which the arm is opened and closed for torque adjustment can be adjusted accurately, and the article can be accurately transferred to the transfer device while suppressing mechanical wear and damage. Can be imported.

The transfer device may further include a first position detection unit that detects a movement position of the pair of arms and a second position detection unit that detects a movement position of the pair of bases. The drive control unit is configured such that the pair of bases are spaced apart with an interval at which the article can be held, and the first position detection unit and the second position detection unit until the pair of arms advance to a position at which the article can be held. The first drive unit and the second drive unit are controlled based on the detection result. The drive control unit controls the first drive unit so that the arms approach each other until the reaction force reaches a predetermined threshold after the pair of arms are arranged at a position where the article can be sandwiched. The drive control unit controls the second drive unit so that the pair of arms retracts into the pair of bases after reaching the threshold value.
Thereby, control is switched from position control to torque control before and after the position where the article can be clamped. For this reason, the idle time by control switching does not generate | occur | produce at the time of clamping operation, and the fall of transfer efficiency can be suppressed.

The transfer device may further include a pinching detection unit that determines whether the pair of arms has pinched the article.
As a result, malfunction can be prevented, and a failure of the transfer device can be detected accurately at an early stage. For example, if the increase in the reaction force is detected even though the clamping detection unit has not detected the clamping of the article, it can be determined that there is an abnormality in the transfer device.

A control method of a transfer device according to another aspect of the present invention is a transfer device for transferring an article to and from a transfer location, and a pair of bases and the article are sandwiched toward the transfer location. A pair of arms respectively provided on the pair of bases so as to be able to advance and retreat, a first drive unit that drives the pair of bases so as to approach and separate from each other, and advance and retreat with respect to the base In this way, the second drive unit that drives the pair of arms, the reaction force detection unit that detects the reaction force from the article when the pair of arms sandwich the article, and the transfer device provided.
The control method includes the following steps.
◎ Reaction force acquisition step for acquiring the reaction force detected by the reaction force detection unit ◎ Drive unit control step for controlling the first drive unit so that the reaction force falls within a predetermined range In the reaction force acquisition step, the first drive unit The torque may be detected as a reaction force.
The control method may further include a retracting step of retracting the pair of arms to the pair of bases by controlling the second drive unit. In that case, the drive unit control process is performed during the retreat process.
In the drive control unit step, the second drive unit may be controlled in addition to the first drive unit so that the reaction force detected by the reaction force detection unit falls within a predetermined range.

  According to the present invention, when the pair of arms holds the article, the reaction force is within a predetermined range, so that the article being transferred can be held with an appropriate force as much as possible.

1 is a schematic plan view of an automatic warehouse in which a transfer device according to an embodiment of the present invention is employed. It is an II-II arrow line view of FIG. 1, and is a figure for demonstrating a rack and a stacker crane. FIG. 3 is a view taken along the line III-III in FIG. 1 for explaining a rack and a stacker crane. The schematic plan view of a transfer apparatus. The schematic side view of a transfer apparatus. The top view which shows the structure of a clamping sensor. The block diagram of a crane control part. The flowchart which shows an example of the loading operation | movement of a drive control part. The flowchart which shows an example of the torque control operation | movement of a drive control part.

(1) Whole automatic warehouse Hereinafter, the automatic warehouse 1 by which 1st Embodiment which concerns on this invention was employ | adopted is demonstrated.
FIG. 1 is a schematic plan view of an automatic warehouse in which the transfer apparatus of one embodiment is adopted, FIG. 2 is a view taken along the line II-II in FIG. 1, and FIG. 3 is a view taken along the line III-III in FIG. is there. In this embodiment, the vertical direction in FIG. 1 is the front-rear X direction of the automatic warehouse 1 (an example of the first direction that is the transfer direction), and the left-right direction in FIG. .
In FIG. 1, an automatic warehouse 1 is mainly composed of a first rack 2a and a second rack 2b that are spaced apart in the front-rear X direction, and a stacker crane 3 that travels between them.

(2) Rack The first rack 2a and the second rack 2b are arranged at the front and rear so as to sandwich the travel path 5 of the stacker crane 3 extending in the left-right Y direction. The first rack 2a and the second rack 2b are adjacent to a number of first struts 7 arranged on the traveling passage 5 side to the left and right at predetermined intervals, and second struts 9 arranged on the opposite side of the traveling passage 5 with predetermined intervals. It has a large number of luggage storage shelves 11 provided between the matching first support column 7 and second support column 9. When the stacker crane 3 places the load W (an example of an article) on the load storage shelf 11, the end surface of the load W on the traveling path side is positioned at a predetermined position of the load storage shelf 11 as shown in FIG. 1. To process.

  In the lowermost luggage storage shelf 11 on the left side of the first rack 2a, a storage station 17 for storing the luggage W is disposed. On the leftmost luggage storage shelf 11 on the left side of the second rack 2b, a delivery station 19 for delivering the luggage W is disposed.

(3) Stacker crane In FIGS. 1, 2 and 3, an upper guide rail 21a and a lower guide rail 21b are provided along the traveling path 5, and the stacker crane 3 is provided on the upper guide rail 21a and the lower guide rail 21b. Is guided so as to be movable in the left-right Y direction. The stacker crane 3 conveys the load W between the large number of load storage shelves 11, the storage station 17, and the output station 19.

  As shown in FIGS. 2 and 3, the stacker crane 3 includes a traveling carriage 22, a lifting platform 27, and a transfer device 29 provided on the lifting platform 27. The traveling carriage 22 has a left traveling wheel 23a and a right traveling wheel 23b at both ends in the left-right Y direction. The left traveling wheel 23a and the right traveling wheel 23b are rotatably supported by bearings on the traveling carriage 22 and travel on the lower guide rail 21b. The traveling carriage 22 is guided to the lower guide rail 21b by a front guide roller 23c and a rear guide roller 23d arranged at both ends with the lower guide rail 21b interposed therebetween. The right traveling wheel 23 b is driven by a traveling motor 87. A left mast 25 a and a right mast 25 b are fixed inside the left traveling wheel 23 a and the right traveling wheel 23 b of the traveling carriage 22. The left mast 25a and the right mast 25b extend in the vertical direction. The lifting platform 27 is mounted on a left mast 25a and a right mast 25b provided on the traveling carriage 22 so as to be movable up and down. A control panel 80 that houses a crane control unit 81 (see FIG. 7) for controlling the stacker crane 3 is attached to the right mast 25b.

(4) Transfer Device FIG. 4 is a schematic plan view of the transfer device, and FIG. 5 is a schematic side view of the transfer device.
The transfer device 29 is a device for transferring the load W between the stacker crane 3, the warehousing station 17, the unloading station 19, and the luggage storage shelf 11. As shown in FIGS. 4 and 5, the transfer device 29 includes a device main body 31 that also functions as the lifting platform 27, a conveyor unit 32, a clamp unit 33 that moves the load W in the first direction, and a conveyor unit 32. And a drive control unit 81c (see FIG. 7) for controlling the clamp unit 33.

  As shown in FIG. 4, the conveyor portion 32 is provided at the center portion of the apparatus main body 31 in the left-right Y direction. The conveyor unit 32 places the luggage W in the apparatus main body 31 and moves it toward the luggage storage shelf 11 along the front-rear X direction (transfer direction). The clamp part 33 is provided outside the conveyor part 32 of the apparatus main body 31. The clamp part 33 clamps the luggage W and moves it to the luggage storage shelf 11 side.

(4-1) Device Main Body The device main body 31 has a load placement area 31a on which the load W can be placed. The luggage W is placed on the apparatus main body 31 such that one end in the X direction is located at a predetermined position in the luggage placement area 31a. For example, an end portion away from the first rack 2a or the second rack 2b to which the load W is transferred is a predetermined position of the load placement area 31a (from the first rack 2a or the second rack 2b to be transferred). The baggage W is placed on the baggage placement region 31a so as to be located in the vicinity of the end of the separated position. When one end in the X direction, which is a reference when placing the load W on the load placement area 31a, is the end that is clamped by the clamp 33, and the first rack 2a is a transfer target. 4 is an end portion on the left side of FIG. 4, and is an end portion on the right side of FIG. 4 when the second rack 2 b is a transfer target.

(4-2) Conveyor unit The conveyor unit 32 is used to place and move the luggage W, and is provided in the central portion of the apparatus main body 31 in the left-right Y direction, as shown in FIGS. 4 and 5. . The conveyor part 32 has the 1st conveyor unit 32a and the 2nd conveyor unit 32b which are arrange | positioned symmetrically with respect to the center, and the conveyor drive part 42 which drives these. The first conveyor unit 32a and the second conveyor unit 32b are, for example, belt conveyors. The first conveyor unit 32a and the second conveyor unit 32b have the same structure. The conveyor drive unit 42 includes a conveyor drive motor 94 and a drive shaft 40 that transmits power from the conveyor drive motor 94 to a drive pulley (not shown). In addition, as a kind of conveyor, it may not be a belt conveyor but a roller conveyor, a chain conveyor, etc. may be sufficient.

(4-3) Clamp part The structure of the clamp part 33 is demonstrated using FIG.4 and FIG.5. The clamp portion 33 is a mechanism that sandwiches both side surfaces of the luggage W and moves them in the front-rear X direction. The clamp unit 33 includes a first base 51 a and a second base 51 b, a first arm 53 a and a second arm 53 b, a first drive unit 60, and a second drive unit 61.
The 1st drive part 60 makes the 1st base 51a and the 2nd base 51b approach and separate mutually. The second drive unit 61 moves the first arm 53a and the second arm 53b forward and backward in synchronization with the first base 51a and the second base 51b. The first arm 53a and the second arm 53b are arranged so that the centers in the front-rear X direction coincide with the centers in the front-rear X direction of the first base 51a and the second base 51b at the home position shown in FIG. Further, in the left-right Y direction, the first arm 53a and the second arm 53b are arranged farthest apart.

(4-4) First Base and Second Base The first base 51a and the second base 51b are provided in the apparatus main body 31 so as to be able to approach and separate from each other in the left-right Y direction. The 1st base 51a and the 2nd base 51b are arrange | positioned at the left-right Y direction both sides of the luggage | load placement area | region 31a. The first base 51a and the second base 51b support the first arm 53a and the second arm 53b movably in the front-rear X direction on the inner surfaces facing each other. The first base 51a and the second base 51b are supported by the apparatus main body 31 so as to be movable in the left-right Y direction. The first base 51a and the first arm 53a and the second base 51b and the second arm 53b have a mirror image structure.

(4-5) 1st arm and 2nd arm The 1st arm 53a and the 2nd arm 53b are each provided in the 1st base 51a and the 2nd base 51b so that advance and retreat are possible in the direction of order X.
The first arm 53a has a first intermediate arm portion 54a and a first tip arm portion 55a. The second arm 53b has a second intermediate arm portion 54b and a second tip arm portion 55b. The first intermediate arm portion 54a and the second intermediate arm portion 54b are supported on the inner side surfaces of the first base 51a and the second base 51b so as to be movable in the front-rear X direction. The first intermediate arm portion 54a and the second intermediate arm portion 54b are substantially rectangular plate-shaped members.

  The first tip arm portion 55a and the second tip arm portion 55b are supported on the inner side surfaces of the first intermediate arm portion 54a and the second intermediate arm portion 54b so as to be movable in the front-rear X direction. The first tip arm portion 55a and the second tip arm portion 55b are substantially rectangular plate-like members. The first tip arm portion 55a and the second tip arm portion 55b are connected to the first intermediate arm portion 54a and the second intermediate arm portion 54b through an interlocking mechanism (not shown). The interlocking mechanism operates to move the first tip arm portion 55a and the second tip arm portion 55b at a double speed in conjunction with the movement of the first intermediate arm portion 54a and the second intermediate arm portion 54b.

(4-6) First Drive Unit As shown in FIG. 4, the first drive unit 60 is a mechanism for opening and closing the first base 51a and the second base 51b so as to approach and separate from each other in the left-right Y direction. It is. By this opening / closing drive, the first tip arm portion 55a and the second tip arm portion 55b move to a contact position where they come into contact with both side surfaces of the luggage W and a separation position where they are separated. The first drive unit 60 includes an arm opening / closing motor 90 and a ball screw shaft 62 connected to the arm opening / closing motor 90. Moreover, the 1st drive part 60 has the 1st nut member 64a and the 2nd nut member 64b which screw together with the ball screw shaft 62, as shown in FIG. The first nut member 64a and the second nut member 64b are provided on the first base 51a and the second base 51b, respectively. The screw direction of the ball screw shaft 62 is different at an intermediate portion. For example, the right side in FIG. 5 (lower side in FIG. 4) is a right screw portion 62a, and the left side in FIG. 5 (upper side in FIG. 4) is a left screw portion 62b. is there. As shown in FIG. 6, the first nut member 64a and the second nut member 64b include a nut body 70a having a right-handed or left-handed ball nut portion in which a large number of balls circulating inside are spirally arranged, And a mounting flange 70b provided on the nut body 70a. The mounting flange 70b has a generally rhombus shape.

  As shown in FIG. 5, the 1st nut member 64a and the 2nd nut member 64b are each arrange | positioned on the inner surface which the 1st base 51a and the 2nd base 51b oppose. Here, the first nut member 64a is a right-hand screw member that is screwed into the right-hand thread portion 62a, and the second nut member 64b is a left-hand screw member that is screwed into the left-hand screw portion 62b.

  When the ball screw shaft 62 rotates in one direction by the arm opening / closing motor 90, the first base 51a and the second base 51b move in the opening direction away from each other, and in the other direction by rotating in the other direction. Moving.

(4-7) Second Drive Unit As shown in FIG. 4, the second drive unit 61 reciprocates the first arm 53 a and the second arm 53 b in the front-rear X direction. The second drive unit 61 includes an arm movement motor 92 and a spline shaft 69. A drive sprocket (not shown) is connected to the spline shaft 69 so as to be integrally rotatable and axially movable. The drive sprocket is connected to the first base 51a and the second base 51b so as to be rotatable and impossible in the axial direction. A drive chain that drives the first intermediate arm portion 54a and the second intermediate arm portion 54b back and forth is wound around the drive sprocket. Thereby, the 1st intermediate | middle arm part 54a and the 2nd intermediate | middle arm part 54b expand and contract in the front-back X direction synchronously. Further, as described above, the first distal arm portion 55a and the second distal arm portion 55b expand and contract at a double speed in conjunction with the movement of the first intermediate arm portion 54a and the second intermediate arm portion 54b.

(4-8) Clamping Detection Unit FIG. 6 is a plan view showing the configuration of the clamping sensor.
As shown in FIG. 6, the pinching detection unit 66 is provided on the first nut member 64a and the second nut member 64b. The clamping detection unit 66 is a detection unit for detecting that the cargo W has been clamped when the first arm 53a and the second arm 53b move in the closing direction. The sandwiching detection unit 66 includes a pair of guide shafts 71 fixed to both ends of the mounting flange 70b of the first nut member 64a and the second nut member 64b, a pair of coil springs 72, and a gap detection sensor 73. ing. The guide shaft 71 is disposed through the first base 51a and the second base 51b. The guide shaft 71 guides the nut main body 70a in a direction in which the nut main body 70a is in contact with or separated from the first base 51a or the second base 51b. The guide shaft 71 has a large-diameter head portion 71a, a small-diameter male screw portion 71b, and a shaft portion 71c having an outer diameter between the head portion 71a and the male screw portion 71b. The guide shaft 71 is fixed to the mounting flange 70 b by a nut 74. The coil spring 72 is disposed on the outer peripheral side of the guide shaft 71, and is disposed in a compressed state between the head 71a and the first base 51a or the second base 51b. Thereby, the attachment flange 70b which fixes the 1st nut member 64a is urged | biased by the coil spring 72 in the direction joined to the 1st base 51a. Similarly, the mounting flange 70b for fixing the first nut member 64b is urged by the coil spring 72 in the direction in which it is joined to the second base 51b. The gap detection sensor 73 is, for example, a light projecting / receiving photoelectric sensor in which a light projecting unit and a light receiving unit are spaced apart. The detector 75 fixed to the mounting flange 70b moves between the light projecting portion and the light receiving portion of the gap detection sensor 73 based on the relative movement between the first nut portion 64a and the first base 51a. Is arranged. Also on the second nut portion 64b and the second base 51b side, the detector 75 fixed to the mounting flange 70b is arranged so as to move between the light projecting portion and the light receiving portion of the gap detection sensor 73. The gap detection sensor 73 detects a difference in the amount of movement between the first nut member 64a or the second nut member 64b and the first base 51a and the second base 51b, and based on the difference, the first arm 53a and the second arm 53b. It is determined whether or not the baggage W is in the closed position.

  When the ball screw shaft 62 is rotated in one direction by the arm opening / closing motor 90, the first base 51a and the second base 51b move in the opening direction away from each other, and in the other direction, move in the approaching close direction. Then, until the first tip arm portion 55a and the second tip arm portion 55b come in contact with both sides of the load W and pinch the load W, as shown in FIG. The two nut members 64b are biased by the coil spring 72 and are in contact with the first base 51a and the second base 51b. However, when the load W is clamped, the first base 51 a and the second base 51 b are prevented from moving in the closing direction by the load W, but the first nut member 64 a and the second nut member 64 b are attached to the coil spring 72. It can move further in the closing direction against the force. As a result, as shown in FIG. 6B, a gap is generated between the first base 51a and the second base 51b and the mounting flange 70b of the first nut member 64a and the second nut member 64b. This gap is a difference between the movement amount of the first base 51a and the second base 51b and the movement amount of the first nut member 64a and the second nut member 64b. When the gap becomes longer than a predetermined length, the detector 75 is detached from the facing portion of the gap detection sensor 73 and the gap detection sensor 73 is turned on. Thereby, it can be detected that the luggage W is gripped.

(4-9) Reaction Force Detection Unit FIG. 7 is a block diagram of the crane control unit.
The clamp part 33 has a reaction force detection part 65 as a part of a motor drive circuit 89 controlled by a crane control part 81 described later.
The reaction force detection unit 65 includes a current detection circuit 65a. The current detection circuit 65a is an example of a torque detection unit. The current detection circuit 65a is provided in a motor drive circuit 89 for driving the arm opening / closing motor 90 of the first drive unit 60, for example, by pulse width modulation. In the pulse width modulation drive, the current value flowing through the motor is controlled by changing the duty ratio. The current detection circuit 65a detects a current value flowing through the arm opening / closing motor 90. This current value changes according to the torque of the arm opening / closing motor 90. When the first arm 53 a and the second arm 53 b abut on the side surface of the load W and sandwich the load W, the reaction force from the load W is received. In order to maintain the positions of the first arm 53a and the second arm 53b against the reaction force from the load W, the arm opening / closing motor 90 needs a predetermined torque. Accordingly, the reaction force from the load W can be detected from the value of the current flowing through the arm opening / closing motor 90. As described above, since the reaction force can be detected by the value of the current flowing through the arm opening / closing motor 90, it is not necessary to provide a reaction force detection sensor on the first arm 53a or the second arm 53b, and the structure for detecting the reaction force is simple. become.

(5) Crane Control Unit In FIG. 7, the crane control unit 81 of the stacker crane 3 is mounted on the control panel 80 of the stacker crane 3. The crane control unit 81 can communicate with a controller 82 that controls the entire automatic warehouse 1. The crane control unit 81 includes computer hardware such as a CPU and a memory. In FIG. 7, the crane control unit 81 is expressed as a functional block realized by cooperation of the computer hardware and software. The control signal is transmitted and received wirelessly (radio waves), but may be wired.

The crane control unit 81 includes a travel control unit 81 a that controls the traveling and stopping of the traveling carriage 22, an elevation control unit 81 b that performs elevation control of the elevation platform 27, and a drive control unit that performs transfer control of the transfer device 29. 81c as a functional configuration. A traveling motor 87 and an elevating motor 88 are connected to the crane control unit 81. Also, a motor drive circuit (not shown) that drives these motors and a rotary encoder (not shown) that detects the rotational position of the motor are connected. The crane control unit 81 includes an arm opening / closing motor 90, a rotary encoder 91 (an example of a second position detection unit) for detecting a base movement amount (arm opening / closing amount), an arm movement motor 92, and an arm movement amount detection. A rotary encoder 93 (an example of a first position detection unit), a conveyor drive motor 94, a pinching detection unit 66, and a storage unit 96 are connected.
The storage unit 96 stores the intervals between the first arm 53a and the second arm 53b, which are set in a plurality of stages according to the width of the load W, which are included in the conveyance command given from the controller 82.

  Whether or not the load W is being conveyed by the conveyor unit 32 at the time of loading is actually determined that the tip of the load W (the end on the load storage shelf 11 side) is disposed in the transfer device 29. Judgment based on. For example, based on the fact that the output of the load sensor (not shown) has changed from on to off, it is determined that the load W is being conveyed by the conveyor unit 32. The load sensor is a sensor that detects that the load W protrudes from the transfer device 29, and detects that the load W protrudes outside the load placement area 31a.

  Whether or not the load W is being conveyed from the conveyor unit 32 at the time of unloading is actually determined based on the fact that the tip of the load W is disposed outside the transfer device 29. It is determined that it has not been transported. For example, the determination is made based on the fact that the output of the load sensor has changed from OFF to ON.

(6) Operation of Drive Control Unit (6-1) Loading Operation FIG. 8 is a flowchart illustrating an example of the loading operation of the drive control unit.
An example of the loading operation of the transfer device 29 will be described using the control flowchart of the drive control unit 81c shown in FIG. In FIG. 8, the loading operation after the empty stacker crane 3 reaches the conveyance source will be described. When arriving at the transfer source, the first arm 53a and the second arm 53b are in the most open state according to the width of the load W, and the first arm 53a and the second arm 53b are arranged at the rear end reference position. Has been. Whether the first arm 53 a and the second arm 53 b are in the most open state is determined by the drive control unit 81 c based on the output from the rotary encoder 91.

In step S1 of FIG. 8, the drive control unit 81c drives the arm moving motor 92 and starts to advance from the rear end reference position of the first arm 53a and the second arm 53b. Here, the drive control unit 81c drives the arm moving motor 92 in a direction in which the first arm 53a and the second arm 53b advance toward the first rack 2a or the second rack 2b to be transferred.
In step S2, the drive control unit 81c determines whether or not the first arm 53a and the second arm 53b have advanced a predetermined distance. This determination is made based on the output of the rotary encoder 93. This predetermined distance is an advancing distance at which the first arm 53a and the second arm 53b can clamp the luggage W in the luggage storage rack 11 on the basis of the rear end.

The process returns to step S2 until the first arm 53a and the second arm 53b advance a predetermined distance, and proceeds to step S3 by advancing a predetermined distance.
In step S3, the drive control unit 81c stops the first arm 53a and the second arm 53b.
In step S <b> 4, the drive control unit 81 c starts torque control to be described later for the arm opening / closing motor 90.
In step S5, the drive control unit 81c closes the first arm 53a and the second arm 53b, and the first arm 53a and the second arm 53b clamp the load W. At this time, the drive control unit 81c confirms the clamp of the luggage W based on the output from the pinching detection unit 66. Specifically, it is determined whether or not the current value of the arm opening / closing motor 90 detected by the current detection circuit 65a is within a predetermined range. As described above, in a state where the first arm 53a and the second arm 53b are in contact with the side surface of the load W and sandwich the load W, the arm opening / closing motor 90 receives a reaction force from the load W and receives a predetermined force. Torque is required. When the torque of the arm opening / closing motor 90 is increased, the force for holding the load W by the first arm 53a and the second arm 53b becomes excessive, and the load W may be damaged. Therefore, the drive control unit 81c controls the motor drive circuit 89 so that the current value of the arm opening / closing motor 90 detected by the current detection circuit 65a falls within a predetermined range, and the torque of the arm opening / closing motor 90 is within a predetermined range. To be inside. Accordingly, the first drive unit 60 shown in FIG. 4 is controlled to finely adjust the distance between the first base 51a and the second base 51b, and the load W is sufficient to transfer the load W and damage the load W. It is possible to continue to hold the luggage W with a holding force within a range that does not occur.
In step S6, the drive control unit 81c reverses the arm moving motor 92 to start the retraction of the first arm 53a and the second arm 53b, and retreats the first arm 53a and the second arm 53b at a substantially constant speed. Let Then, the first drive unit 60 is set so that the current value A from the current control circuit 65c is within a predetermined range, that is, the torque holding the load W is within the predetermined range. And finely adjust the distance between the first base 51a and the second base 51b.
Moreover, the drive control part 81c drives the conveyor drive motor 94, and the operation | movement of the conveyor part 32 is started. Here, the conveyor unit 32 drives the load W in the direction in which the load is loaded onto the transfer device 29 from the first rack 2a or the second rack 2b.

  In step S <b> 7, it waits for the conveyor unit 32 to transport the package W. This determination is made based on the output of the load sensor as described above. Thereby, it is possible to detect a holding failure of the luggage W.

When the conveyor unit 32 conveys the package W, the process proceeds from step S7 to step S8.
In step S8, the system waits for the first arm 53a and the second arm 53b to retract by the predetermined distance described above. If the first arm 53a and the second arm 53b are retracted by a predetermined distance, the process proceeds from step S8 to step S9.
In step S9, the drive control unit 81c ends the torque control.
In step S10, the drive control unit 81c stops the retraction of the first arm 53a and the second arm 53b, and stops the driving of the conveyor unit 32. Thus, the luggage W is arranged so that one end in the X direction is at a predetermined position in the luggage placement region 31a.

  Here, when the load W is loaded on the transfer device 29, the clamping force does not become excessively large even if the rigidity increases due to the first arm 53a and the second arm 53b retracting. For this reason, the luggage W is difficult to deform.

(6-2) Unloading operation In the unloading operation to the transfer location, torque control is performed when loading the load W onto the stacker crane 3 at the warehousing station 17, and then the load W according to the transfer location. When it is necessary to arrange one end in the X direction at a predetermined position, the torque control is once terminated and the luggage W is arranged at the predetermined position by the conveyor unit 32. When the load W is arranged so that one end is in a predetermined position, the torque control is ended. Upon arrival at the transfer location, torque control is started, torque control is maintained until the first arm 53a and the second arm 53b are advanced by a predetermined distance, and torque control is terminated when the predetermined distance is moved.

  As a result, when unloading the luggage W to the luggage storage shelf 11, even if the first arm 53a and the second arm 53b advance, the clamping force can be maintained, and the luggage W cannot be clamped. It becomes difficult to become.

(6-3) Torque Control Operation FIG. 9 is a flowchart illustrating an example of the torque control operation of the drive control unit.
In the torque control operation, the start of torque control is awaited in step S21 of FIG. When torque control is started, the process proceeds to step S22.
In step S22, the current value A detected by the current detection circuit 65a is captured.
In step S23, the drive control unit 81c determines whether or not the captured current value A is less than the lower limit current value ASL of a predetermined range of current values. The current value in the predetermined range may be set in a plurality of stages according to the rigidity of the luggage W.
In step S24, the drive control unit 81c determines whether or not the acquired current value A exceeds the upper limit current value ASH of a predetermined range of current values.
In step S25, the drive control unit 81c determines whether or not the torque control is finished. The process returns to step S22 until the torque control is finished, and when finished, the process is finished.

When the drive control unit 81c determines that the acquired current value A is less than the lower limit current value ASL of a predetermined range of current values, the process proceeds from step S23 to step S26.
In step S26, the drive control unit 81c determines whether or not the current duty ratio D is less than a preset maximum duty ratio Dmax. The maximum duty ratio Dmax may be set in a plurality of stages according to the rigidity of the luggage W, for example. If the drive control unit 81c determines that it is less than the preset maximum duty ratio Dmax, the process proceeds to step S27, and if the drive control unit 81c determines that it is greater than or equal to the preset maximum duty ratio Dmax, the step S27 is skipped. Then, the process proceeds to step S24.
In step S27, the duty ratio D is increased by a predetermined increment DI, and the process proceeds to step S24. This increment DI is, for example, about 5% duty.

When the drive control unit 81c determines that the acquired current value A exceeds the upper limit current value ASH of a predetermined range of current values, the process proceeds from step S24 to step S28.
In step S28, the drive control unit 81c determines whether or not the current duty ratio D exceeds a preset minimum duty ratio Dmin. The minimum duty ratio Dmin may be set in a plurality of stages according to the rigidity of the luggage W, for example. If the drive control unit 81c determines that it is less than the preset minimum duty ratio Dmin, the process proceeds to step S29, and if the drive control unit 81c determines that it is equal to or less than the preset minimum duty ratio Dmin, step S29 is skipped. Then, the process proceeds to step S25.
In step S29, the duty ratio D is increased by a predetermined decrement DI, and the process proceeds to step S24. This decrement DI is, for example, about 5% duty.
Here, when the first arm 53a and the second arm 53b are holding the load W by torque control, the reaction force is within a predetermined range. It becomes possible to pinch with a strong force.

(6-4) Other Embodiments of Loading Operation In the above-described embodiments, the first arm 53a and the second arm 53b are retracted at a substantially constant speed, but drive control is performed according to the torque value. The part may also change the retreat speed of the arm. For example, when the bending of the arm with respect to the base is large, the distance by which the first base 51a and the second base 51b are moved for torque adjustment increases. Therefore, it is preferable to adjust the retraction speed of the first arm 53a and the second arm 53b so as to correspond to the opening / closing speed of the first arm 53a and the second arm 53b in the torque control operation. A loading operation taking such points into consideration will be described below.

  In the flowchart of the loading operation shown in FIG. 8, in step S35, the drive control unit 81c closes the first arm 53a and the second arm 53b. At this time, the drive control unit 81c confirms the clamp of the luggage W based on the output from the pinching detection unit 66. The drive control unit 81c finely adjusts the interval between the first base 51a and the second base 51b so as to obtain a clamping force set based on the material and size of the luggage W, and the current value from the current control circuit 65c. The value of A is set within a predetermined range.

In step S6, the drive control unit 81c drives the arm movement motor 92 to start the retraction of the first arm 53a and the second arm 53b.
At this time, the first drive unit 60 is controlled so that the value of the current value A from the current control circuit 65c is within a predetermined range, that is, the torque holding the load W is within the predetermined range. Then, the interval between the first base 51a and the second base 51b is finely adjusted.
Further, when the adjustment amount of the distance between the first base 51a and the second base 51b is large, the drive control unit 81c slows the retraction speed of the first arm 53a and the second arm 53b by the arm moving motor 92. For example, when the drive control unit 81c performs torque control so that the value of the current value A from the current control circuit 65c is within a predetermined range, when the fluctuation amount of the current value A exceeds a predetermined value, The current value of the arm moving motor 92 is reduced by a corresponding amount.
Further, the drive control unit 81 c drives the conveyor drive motor 94 to start the operation of the conveyor unit 32. At this time, the drive control unit 81c controls the conveyor drive motor 94 so that the operation in the loading direction by the conveyor unit 32 is synchronized with the retraction speed of the first arm 53a and the second arm 53b.

The drive control unit 81c continuously performs the torque control of the arm opening / closing motor 90 and the retraction speed control of the arm moving motor 92 as described above until the end of the torque control in step S9.
This makes it possible to accurately adjust the balance between the speed at which the arm is retracted and the speed at which the arm is opened / closed for torque adjustment, even when the arm bends greatly with respect to the base. The article can be accurately taken into the transfer device while preventing damage.

(7) Effects of Embodiment (A) The transfer device 29 (an example of a transfer device) transfers a load W (an example of an article) to and from the luggage storage shelf 11 (an example of a transfer location). Device. The transfer device 29 includes a first base 51a and a second base 51b (an example of a pair of bases), a first arm 53a and a second arm 53b (an example of a pair of arms), and a first drive unit 60 (first An example of a drive unit), a second drive unit 61 (an example of a second drive unit), a reaction force detection unit 65 (an example of a reaction force detection unit), a drive control unit 81c (an example of a drive control unit), It has.
The first arm 53a and the second arm 53b are respectively provided on the first base 51a and the second base 51b so as to be able to advance and retreat toward the luggage storage shelf 11 while sandwiching the luggage W.
The first driving unit 60 drives the first base 51a and the second base 51b so as to approach and separate from each other.
The second drive unit 61 drives the first arm 53a and the second arm 53b so as to advance and retract with respect to the first base 51a and the second base 51b.
The reaction force detector 65 detects the reaction force from the load W when the first arm 53a and the second arm 53b hold the load W.
The drive control unit 81c can control the first drive unit 60 so that the reaction force detected by the reaction force detection unit 65 falls within a predetermined range.

  In the transfer device 29, when the first arm 53a and the second arm 53b are arranged at a position where the load W can be clamped, the first drive unit 60 is moved in a direction in which the first base 51a and the second base 51b approach each other. Driven by. Then, when the first arm 53a and the second arm 53b pinch the load W, the drive control unit 81c controls the first drive unit 60 so that the reaction force detected by the reaction force detection unit 65 falls within a predetermined range. . Here, when the first arm 53a and the second arm 53b are holding the load W, the reaction force is within a predetermined range, so the load W being transferred is held with an appropriate force as much as possible. become able to.

(B) In the transfer device 29, the reaction force detection unit 65 may include a current detection circuit 65a (an example of a torque detection unit) that detects the torque of the first drive unit 60 as a reaction force. The drive control unit 81c may control the first drive unit 60 based on the current value detected by the current detection circuit 65a so that the reaction force is within a predetermined range. Thereby, for example, when the first drive unit 60 electrically drives the first base 51a and the second base 51b, the torque can be easily detected by the value of the current flowing through the first drive unit 60. For this reason, the reaction force can be easily detected without using a reaction force detection sensor (for example, a sensor such as a pressure sensor or a piezoelectric sensor) at the load holding portion of the moving first arm 53a and second arm 53b. Thus, the configuration of the transfer device 29 can be simplified.
(C) When the drive control unit 81c retracts the first arm 53a and the second arm 53b into the first base 51a and the second base 51b, the reaction force detected by the reaction force detection unit is within a predetermined range. As such, the first drive unit may be controlled.
As a result, the load W can be taken into the transfer device 29 while holding the load W with a force sufficient to transfer the load W and not damaging the load W.
(D) The drive control unit 81c can also control the second drive unit 61. When the drive control unit 81c retracts the first arm 53a and the second arm 53b into the first base 51a and the second base 51b, In addition, the first drive unit 60 and the second drive unit 61 may be controlled so that the reaction force detected by the reaction force detection unit 65 falls within a predetermined range.
Thereby, it is possible to accurately adjust the balance between the speed at which the first arm 53a and the second arm 53b are retracted and the speed at which the first base 51a and the second base 51b are opened and closed for torque adjustment. The article W can be accurately taken into the transfer device 29 while suppressing mechanical wear and breakage.

(E) The transfer device 29 detects the movement positions of the first arm 53a and the second arm 53b, and the movement positions of the first base 51a and the second base 51b. And a rotary encoder 91 (an example of a second position detection unit) that detects the above. The drive control unit 81c moves to a position where the first arm 53a and the second arm 53b can clamp the load W, with the first base 51a and the second base 51b spaced apart so that the load W can be held. Up to this point, the first drive unit 60 and the second drive unit 61 are controlled based on the detection results of the rotary encoder 93 and the rotary encoder 91. After the first arm 53a and the second arm 53b are arranged at positions where the load W can be sandwiched, the first arm 53a and the second arm 53b are brought close to each other until a predetermined threshold value is reached. The arm 53a and the second arm 53b may be retracted into the first base 51a and the second base 51b. Thereby, the control is switched from the position control to the torque control before and after the position where the load W can be clamped. For this reason, the idle time by control switching does not generate | occur | produce at the time of clamping operation, and the fall of transfer efficiency can be suppressed.
(F) The transfer device 29 may further include a pinching detection unit 66 that determines whether the first arm 53a and the second arm 53b have pinched the load W. As a result, malfunction can be prevented, and a failure of the transfer device can be detected accurately at an early stage. For example, if the increase in the reaction force is detected even though the holding detection unit 66 has not detected the holding of the load W, it can be determined that there is an abnormality in the transfer device 29.

(8) Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. In particular, a plurality of embodiments and modifications described in this specification can be arbitrarily combined as necessary.

  (A) In the above embodiment, the reaction force is detected by the value of the current flowing through the arm opening / closing motor 90, but the present invention is not limited to this. For example, a sensor capable of detecting a force, such as a pressure sensor or a piezoelectric sensor, may be disposed in the holding portion of the load W of the first arm 53a and / or the second arm 53b to detect the reaction force. Further, the reaction force may be detected by other means such as the length of the coil spring 72 of the pinching detection unit 66.

  (B) In the above-described embodiment, the first arm 53a includes the first intermediate arm portion 54a and the first tip arm portion 55a (or the second arm 53b includes the second intermediate arm portion 54b and the second tip arm portion 55b). However, the present invention is not limited to such an embodiment. Each of the 1st arm 53a and the 2nd arm 53b may be comprised by one arm part.

  (C) In the above embodiment, the load W is transferred on the basis of the rear end in order to simplify the control. However, the present invention is not limited to this. The load W may be transferred based on the center reference and the tip reference.

  (D) In the said embodiment, although the belt conveyor was illustrated as a conveyor part, this invention is not limited to this. As the conveyor unit, a chain conveyor or a roller conveyor capable of transporting loads may be used.

  (E) In the above embodiment, the ball screw shaft having a left screw and a right screw is used for the first drive unit, but the present invention is not limited to this. For example, the opening / closing drive unit may be configured using a pantograph structure, a chain, or the like.

  (F) In the embodiment described above, one transfer device 29 is mounted on the stacker crane 3, but a plurality of transfer devices may be mounted on the stacker crane in the left-right direction.

(G) In the said embodiment, although the transfer apparatus 29 mounted in the stacker crane 3 was illustrated, this invention is not limited to this. The present invention can be applied to all transfer devices that sandwich an article with a pair of arms.
(H) In the above embodiment, the torque control is started when the bases are brought close to each other from the state where the arms (bases) are most opened and the arms are advanced, but the present invention is not limited to this. For example, the control may be performed based on the output of the rotary encoder 91 while the bases are brought close to a predetermined distance, and the control may be switched from the predetermined distance to the torque control.

  The transfer device according to the present invention is widely applicable to, for example, a stacker crane of an automatic warehouse.

DESCRIPTION OF SYMBOLS 1 Automatic warehouse 2a 1st rack 2b 2nd rack 3 Stacker crane 5 Traveling path 7 1st support | pillar 9 2nd support | pillar 11 Luggage storage shelf 17 Warehousing station 19 Unloading station 21a Upper guide rail 21b Lower guide rail 22 Traveling carriage 23a Left traveling wheel 23b Right traveling wheel 23c Front guide roller 23d Rear guide roller 25a Left mast 25b Right mast 27 Lifting table 29 Transfer device 31 Device body 31a Luggage placement region 32 Conveyor portion 32a First conveyor unit 32b Second conveyor unit 33 Clamp portion 40 Drive shaft 42 Conveyor drive part 51a 1st base 51b 2nd base 53a 1st arm 53b 2nd arm 54a 1st intermediate arm part 54b 2nd intermediate arm part 55a 1st tip arm part 55b 2nd tip arm part 60 1st drive 61 2nd drive part 62 Ball screw shaft 62a Right thread part 62b Left thread part 64a 1st nut member 64b 2nd nut member 65 Reaction force detection part 65a Current detection circuit 66 Clamping detection part 69 Spline shaft 70a Nut main body 70b Mounting flange 71 Guide shaft 71a Head portion 71b Male thread portion 71c Shaft portion 72 Coil spring 73 Gap detection sensor 74 Nut 75 Detector 80 Control panel 81 Crane control portion 81a Travel control portion 81b Elevation control portion 81c Drive control portion 82 Controller 87 Traveling motor 88 Elevation Motor 89 motor drive circuit 90 arm opening / closing motor 91 rotary encoder 92 arm moving motor 93 rotary encoder 94 conveyor drive motor 96 storage unit

Claims (9)

A transfer device for transferring an article to and from a transfer location,
A pair of bases;
A pair of arms respectively provided on the pair of bases so as to be able to advance and retreat toward the transfer place by sandwiching the article;
A first driving unit that drives the pair of bases so as to approach and separate from each other;
A second drive unit that drives the pair of arms to advance and retract with respect to the pair of bases;
A reaction force detection unit that detects a reaction force from the article when the pair of arms sandwich the article ;
When the pair of arms are retracted into the pair of bases, the first drive unit and the second drive unit are controlled so that the reaction force detected by the reaction force detection unit is within a predetermined range. A drive control unit for adjusting the holding force of the pair of arms and the retraction speed of the pair of arms,
A transfer apparatus comprising: The first drive unit includes an arm open / close motor and an open / close drive mechanism that moves the pair of bases closer to and away from each other according to the drive of the arm open / close motor,
The reaction force detection unit includes a current detection circuit that detects a current value flowing through the arm opening and closing motor, detects a change in the current value detected by the current detection circuit as a reaction force from the article,
The transfer device according to claim 1, wherein the drive control unit performs drive control of the arm opening / closing motor so that a current value detected by the current detection circuit falls within a predetermined range. The second drive unit includes an arm movement motor, and an arm movement mechanism that moves the pair of arms forward and backward from the respective bases according to the drive of the arm movement motor,
3. The drive control unit according to claim 2, wherein the drive control unit drives and controls the arm movement motor such that an advance or retreat speed of the pair of arms by the arm movement motor is synchronized with drive control of the arm opening / closing motor. Transfer device. The first drive unit includes an arm open / close motor and an open / close drive mechanism that moves the pair of bases closer to and away from each other according to the drive of the arm open / close motor,
The second drive unit includes an arm movement motor, and an arm movement mechanism that moves the pair of arms forward and backward from the respective bases according to the drive of the arm movement motor,
The said drive control part performs drive control of the said arm movement motor so that the advance or retreat speed | velocity | rate of said pair of arms by the said arm movement motor may synchronize with drive control of the said arm opening / closing motor. Transfer equipment. A first position detection unit for detecting a movement position of the pair of arms;
A second position detection unit for detecting a movement position of the pair of bases;
Further comprising
The drive control unit
The first position detection unit and the second position detection unit until the pair of bases are spaced apart with an interval at which the article can be clamped and the pair of arms advance to a position at which the article can be clamped. Controlling the first drive unit and the second drive unit based on the detection result of
The drive control unit controls the first drive unit so that the arms approach each other until the reaction force reaches a predetermined threshold after the pair of arms are disposed at a position where the pair of arms can be sandwiched. And
The transfer device according to claim 1, wherein the drive control unit controls the second drive unit so that the pair of arms retracts into the pair of bases after reaching the threshold value. A first position detection unit for detecting a movement position of the pair of arms;
A second position detection unit for detecting a movement position of the pair of bases;
Further comprising
The drive control unit
The first position detection unit and the second position detection unit until the pair of bases are spaced apart with an interval at which the article can be clamped and the pair of arms advance to a position at which the article can be clamped. Controlling the first drive unit and the second drive unit based on the detection result of
Further, after the pair of arms are arranged at a position where the article can be sandwiched, the arms are brought close to each other until the reaction force reaches a predetermined threshold value,
The transfer device according to claim 1, further comprising: retracting the pair of arms to the pair of bases after reaching the threshold value.   4. The drive control unit according to claim 3, wherein when the adjustment amount of the distance between the pair of bases by the arm opening / closing motor is large, the drive speed of the pair of arms by the arm moving motor is slowed down. Transfer equipment.   5. The drive control unit according to claim 4, wherein when the adjustment amount of the distance between the pair of bases by the arm opening / closing motor is large, the advancing or retracting speed of the pair of arms by the arm moving motor is slowed down. Transfer equipment. A transfer device for transferring an article to and from a transfer location, the pair of bases, and the pair of bases so as to be able to advance and retreat toward the transfer location while sandwiching the article A pair of arms provided on the base, a first drive unit that drives the pair of bases so as to approach and separate from each other, and a drive of the pair of arms so as to advance and retract relative to the pair of bases A control method for a transfer apparatus comprising: a second drive unit; and a reaction force detection unit that detects a reaction force from the article when the pair of arms sandwich the article.
A reaction force acquisition step of acquiring the reaction force detected by the reaction force detector ;
A retreating step of retracting the pair of arms to the pair of bases by controlling the second drive unit ;
The pair of arms are controlled by controlling the first driving unit and the second driving unit so that the reaction force detected by the reaction force detection unit is within a predetermined range. A drive unit control step for adjusting the clamping force and the retraction speed of the pair of arms, respectively;
A control method for a transfer apparatus comprising:

Images