JP4158537B2 - Unmanned cargo handling vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an unmanned cargo handling vehicle used for transporting and unloading various cylindrical loads (for example, roll paper).
[0002]
[Prior art]
An unmanned forklift is sometimes used as a cargo handling vehicle used for carrying and unloading loads (hereinafter referred to as “workpieces”) due to a recent demand for labor saving and the like (see Patent Document 1).
The unmanned forklift moves forward toward the workpiece based on a command from a host device such as a controller, stops after detecting the workpiece by a contact type sensor (contact type sensor) provided in the forklift, and stops the workpiece at the stop position. It is configured to grip.
[0003]
A pair of long and short clamps that can be opened and closed to grip the side of the workpiece from both the left and right sides (diameter in both directions), especially when carrying a cargo handling work with a cylindrical workpiece such as roll paper with its axis arranged vertically. An arm is attached to the front of the vehicle.
The pair of clamp arms includes a shorter short arm fixed to the holder and a longer long arm that is rotatable with respect to the holder. The clamp arm is opened and closed by rotating the long arm with a cylinder.
Furthermore, a pad is rotatably provided at the tip of each arm via a hinge pin, and a work is held between these pads.
[0004]
In order to detect a workpiece, a limit switch which is a contact type sensor is generally provided on a pad on the short arm side. When the short arm comes into contact with the workpiece, the limit switch emits a signal and the forklift stops. After the forklift stops, the long arm rotates with respect to the holder, and the work is gripped.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-29697 (FIG. 1)
[0006]
[Problems to be solved by the invention]
With this configuration, in order to grip the workpiece smoothly and reliably with the clamp arm, place the workpiece at a position where the straight line connecting the rotation centers of each pad (each hinge pin) passes almost through the center of the workpiece, and clamp it. It is considered ideal to perform an arm gripping operation.
[0007]
However, the workpiece is not always accurately placed at such a position, and there is a possibility that the workpiece is deviated from an optimum position for gripping (hereinafter referred to as “ideal gripping position”).
If the workpiece is misaligned, the clamp arm is gripped while the straight line connecting the pivot centers (hinge pins) of the pads provided at the tips of the arms is far away from the center of the workpiece. Will be done. As a result, even if the workpiece cannot be gripped, even if it can be gripped, it becomes an inappropriate gripping state (that is, deep gripping or shallow gripping), and the workpiece falls off while trying to continue the cargo handling work as it is, In addition to loss of time, there is a risk of damaging the work itself and articles around the drop point.
[0008]
The present invention has been made in view of the above circumstances, and its purpose is to detect the position of the workpiece before gripping the workpiece and determine that the workpiece is in a state where it can be properly gripped by the clamp arm. An object of the present invention is to provide an unmanned cargo handling vehicle that ensures that the work is properly gripped by the clamp arm and that is excellent in work efficiency by performing the gripping operation above.
[0009]
[Means for Solving the Problems]
The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.
[0010]
That is, 1st invention In an unmanned cargo handling vehicle provided with a clamp arm that can be opened and closed to grip a cylindrical workpiece from both sides in the radial direction, a workpiece edge detecting means for detecting at least three edge portions of the workpiece, and a vehicle The travel distance detection means for detecting the travel distance of itself, the disposition position of the work edge detection means on the vehicle, and the travel when the work edge detection means detects each of the three locations. The workpiece center position calculating means for calculating the center position of the workpiece at the time of the gripping operation of the clamp arm using at least the travel distance of the vehicle detected by the distance detecting means, and calculated by the workpiece center position calculating means. Determining means for determining whether or not the clamp arm can properly grip the workpiece based on the center position of the workpiece, and the clamp arm When arm said determining means and a suitably graspable to determine the work, is operated in a direction to close the clamp arms, in which are provided a clamp arm control unit.
[0011]
Second invention The determination means calculates a positional deviation amount between the current center position of the workpiece calculated by the workpiece center position calculation means and a predetermined optimum center position, and the obtained positional deviation amount. Is within a predetermined value, it is determined that the clamp arm is in a state in which the workpiece can be properly gripped.
[0012]
Third invention The sensor that constitutes the workpiece edge detection means includes a non-contact type sensor, and this non-contact type sensor is configured to detect two edges of the workpiece with one sensor. It is.
[0013]
4th invention The workpiece edge detecting means is composed of a plurality of sensors, and at least one of the plurality of sensors is arranged on the vehicle with a deviation in the left-right direction of the body relative to the other sensors. Is.
[0014]
5th invention The pair of clamp arms includes a movable side arm and a fixed side arm, and the sensor constituting the workpiece edge detecting means includes a contact type sensor attached to the fixed side arm. is there.
[0015]
6th invention The sensor constituting the workpiece edge detecting means is only a non-contact type sensor.
[0016]
7th invention The sensor constituting the workpiece edge detecting means includes one or a plurality of non-contact sensors, and at least one of the non-contact sensors is more than the clamp arm than the clamp arm. It can be attached to a close position.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the invention will be described.
FIG. 1 is an overall side view of an unmanned forklift according to a first embodiment of the present invention. FIG. 2A is a partial side view showing a state where the unmanned forklift grips the workpiece at the holding position, and FIG. 2B is a partial plan view of the same. FIG. 3 is a block diagram showing an electrical configuration of the unmanned forklift.
[0018]
[First embodiment]
As shown in FIG. 1, an unmanned forklift 1 as a first embodiment of an unmanned cargo handling vehicle of the present invention has a mast 2 that extends in a vertical direction at a front portion of the vehicle. A lift bracket 3 a that is lifted and lowered along the mast 2 is mounted in front of the mast 2. A holder 4 that holds a pair of clamp arms 5 and 6 is attached to the front surface of the lift bracket 3a via a rotating device 3b. As a result, the holder 4 can rotate around the horizontal axis together with the clamp arms 5 and 6.
[0019]
A bar 12 made of, for example, H-shaped flange steel or the like is attached to the upper part of the holder 4 to which the clamp arms 5 and 6 are attached so as to extend along the traveling direction. The bar 12 extends further forward than the clamp arms 5 and 6, and a direct reflection type optical sensor (first sensor) 41 provided near the tip of the bar 12 is positioned forward of the clamp arms 5 and 6 in the traveling direction. To do.
[0020]
The optical sensor 41 outputs an ON signal to the travel control unit 21 (see FIG. 3), which will be described later, when there is an object at a predetermined height in the downward direction indicated by a one-dot chain line in the figure, and an OFF signal when there is no object. Thereby, as will be described in detail later, it is possible to detect two places on the edge of the workpiece W.
[0021]
On the other hand, the workpiece W that is the object of the cargo handling work arranged in the traveling direction of the unmanned forklift 1 is placed on the pallet 30 of the self-propelled carriage 32. The self-propelled carriage 32 is disposed on the support base 33 and can move only in the direction perpendicular to the paper surface of FIG. 1 on a plane slightly above the running surface of the unmanned forklift 1.
[0022]
FIGS. 2A and 2B show a state where the workpiece W is gripped by the clamp arms 5 and 6 of the unmanned forklift 1. The clamp arms 5 and 6 are constituted by a short short arm (fixed side arm) 5 and a long long arm (movable side arm) 6 which are arranged to face each other.
As shown in FIG. 2B, the workpiece W has a cylindrical shape having a circular plane having a diameter D, and the pallet 30 has a substantially square plane that is slightly larger than the workpiece W. In this embodiment, the case where the diameter D of the workpiece | work W is not constant, and the workpiece | work W of various diameters is transferred is assumed.
In FIG. 2 (a), the work W is drawn with a two-dot chain line for the sake of convenience, and the long arm 6 that should not be shown in the figure is hidden behind.
[0023]
Here, the workpiece gripping mechanism of the unmanned forklift 1 including the clamp arms 5 and 6 will be described in more detail with reference to FIG. The proximal end portion of the short arm 5 is fixed to the holder 4, while the proximal end portion of the long arm 6 is attached to the holder 4 so as to be rotatable. A cylinder 7 is interposed between the holder 4 and the long arm 6, and the long arm 6 is rotated by the expansion and contraction drive of the cylinder 7. Pads 8 and 9 each having a curved clamping surface are provided at the tips of the clamp arms 5 and 6 so as to be rotatable via hinge pins 10. With the above configuration, the cylinder 7 can be expanded and contracted to open and close the pair of clamp arms 5 and 6 so that the columnar workpiece W can be gripped from both sides in the radial direction.
[0024]
As shown in FIG. 2 (b), the bar 12 disposed above the clamp arms 5 and 6 is attached to the upper center of the holder 4 in the width direction and extends on a line substantially coincident with the center line in the lateral direction of the body. I'm out. The bar 12 and the clamp arms 5 and 6 move together in the vertical direction by raising and lowering the lift bracket 3a.
[0025]
Here, the position of the workpiece W when gripped by the clamp arms 5 and 6 is a position shown in FIG. 2B, that is, a straight line connecting the rotation centers (the hinge pins 10) of the pads 8 and 9. It is considered that the position passing through the vicinity of the center of the workpiece W is optimal.
Therefore, regarding the relative positions of the unmanned forklift 1 and the workpiece W, the ideal position shown in FIG. 2B is referred to as an “ideal gripping position” in this specification. The center of the workpiece W at the ideal gripping position is indicated by reference numeral Oi in FIG.
[0026]
Next, the electrical configuration of the unmanned forklift 1 will be described with reference to FIG.
The traveling control unit 21 shown in FIG. 3 is electrically connected to the traveling motor 16 and controls forward / backward / stop of the vehicle itself and the traveling speed thereof. More specifically, the traveling control unit 21 causes the vehicle to travel toward a predetermined workpiece W based on a command from a host device (not shown) such as a controller, and the clamp arms 5 and 6 are predetermined while approaching. The vehicle itself is controlled such that it is raised and lowered to a height and then stopped at a gripping position by a method as described later.
[0027]
Further, as shown in FIG. 3, a rotary encoder 17 as a travel distance detecting means is provided in order to detect the travel distance of the vehicle by counting the number of rotations of the travel motor 16. Although not shown in FIGS. 1 and 2, the traveling motor 16 is provided in the rear part of the vehicle, and the rotary encoder 17 is provided in the vicinity of the traveling motor 16.
In addition, a mark reading sensor (not shown) is provided on the bottom surface of the unmanned forklift 1, and a mark readable by the mark reading sensor is attached to an appropriate position on the traveling surface of the unmanned forklift 1 (the floor surface of the work place). ing. With this configuration, when the mark is read, the pulse count of the rotary encoder 17 is reset, and the distance that the unmanned forklift 1 has advanced from the position (reference position) at that time can be detected in the form of a pulse count value. Yes.
[0028]
On the other hand, the opening / closing operation of the clamp arms 5 and 6 is controlled by an arm control unit 25 serving as clamp arm control means. The arm control unit 25 is electrically connected to the cylinder 7 of the rotatable long arm 6 and rotates the long arm 6 by controlling the cylinder 7 to degenerate.
[0029]
Further, the unmanned forklift 1 is provided with a storage unit 22 for storing a program or the like that describes a series of cargo handling work procedures and the like. The travel control unit 21 and the arm control unit 25 control the travel motor 16 and the cylinder 7 with reference to the program stored in the storage unit 22.
It should be noted that the arrangement positions of the optical sensor 41 and the limit switch 42 on the vehicle, the center position of the workpiece W at the ideal gripping position (the position of the center Oi in FIG. 2B), and the like are also stored in the storage unit 22. Has been. These are stored in the form of coordinates on the coordinate system after defining an appropriate coordinate system on the vehicle.
[0030]
Next, the operation of the unmanned forklift 1 will be described with reference to FIGS.
The unmanned forklift 1 moves straight forward toward the workpiece W as shown in FIG. 4 after resetting the pulse count value of the rotary encoder 17 at the reference position (not shown). Then, when the workpiece W reaches the lower side of the optical sensor 41, that is, when the optical sensor 41 detects the edge of the workpiece W, the optical sensor 41 outputs to the traveling control unit 21 shown in FIG. Signal is switched from OFF to ON.
At this time, the traveling control unit 21 immediately informs the work center position calculation unit 23, which is a work center position calculation means, that the optical sensor 41 is turned on.
[0031]
In the workpiece center position calculation unit 23, when the information indicating that the optical sensor 41 is turned on is transmitted from the travel control unit 21, that is, the optical sensor 41 detects the edge of the workpiece W (point A shown in FIG. 5). At the time, the pulse count value of the rotary encoder 17 is stored in the storage unit 22 as the pulse count value at the point A.
[0032]
At this time, the unmanned forklift 1 does not stop, and continues to move toward the workpiece W after the time shown in FIG.
Then, when the optical sensor 41 finishes passing over the workpiece W and the workpiece W no longer exists below, that is, when the optical sensor 41 detects the edge of the workpiece W, the optical sensor 41 is detected. The signal output to the traveling control unit 21 is switched from ON to OFF.
Also at this time, the traveling control unit 21 immediately notifies the work center position calculation unit 23 of information indicating that the optical sensor 41 is turned off.
[0033]
In the work center position calculation unit 23, when the information indicating that the optical sensor 41 is turned off is transmitted from the travel control unit 21, that is, the optical sensor 41 detects the edge of the workpiece W (point B shown in FIG. 6). At the time, the pulse count value of the rotary encoder 17 is stored in the storage unit 22 as the pulse count at the point B.
[0034]
Even at this time, the unmanned forklift 1 does not stop, and continues to advance toward the workpiece W even after the time shown in FIG. However, from the time shown in FIG. 6, the traveling control unit 21 controls the traveling motor 16 to decelerate the unmanned forklift 1. This is to reduce the impact when the short arm 5 comes into contact with the workpiece W and to stop the unmanned forklift 1 immediately when the short arm 5 comes into contact with the workpiece W.
[0035]
Then, when the limit switch 42 attached to the pad 8 of the short arm 5 comes into contact with the peripheral surface of the workpiece W, that is, when the limit switch 42 detects the end of the workpiece W (time shown in FIG. 7). A signal output from the limit switch 42 to the traveling control unit 21 shown in FIG. 3 is switched from OFF to ON. At this time, the traveling control unit 21 immediately stops the forward movement of the unmanned forklift 1 and informs the workpiece center position calculation unit 23 that the limit switch 42 has been turned on.
[0036]
In the workpiece center position calculation unit 23, when the information indicating that the limit switch 42 is turned on is transmitted from the traveling control unit 21, that is, the limit switch 42 detects the edge of the workpiece W (point C shown in FIG. 5). At the time, the pulse count of the rotary encoder 17 is stored in the storage unit 22 as the pulse count at the point C.
[0037]
That is, the optical sensor 41 detects two locations (point A and point B) of the workpiece W, and the limit switch 42 detects one location (point C) of the workpiece W edge. In the present embodiment, the workpiece edge detection means includes two sensors, an optical sensor 41 and a limit switch 42. Based on the detection of the three edges, the center position of the workpiece W is calculated by the workpiece center position calculation unit 23 as described below.
[0038]
First, the workpiece center position calculation unit 23 calculates the position of the point A and the position of the point B at the time shown in FIG.
First, after the point A is detected by the optical sensor 41 in FIG. 5, the distance that the unmanned forklift 1 has advanced from the time when the state shown in FIG. 7 is reached is calculated. This is because the pulse count value of the rotary encoder 17 stored in the storage unit 22 at the time of FIG. 5 and the pulse count value of the rotary encoder 17 stored in the storage unit 22 at the time of FIG. It is obtained by multiplying the travel distance of the unmanned forklift 1 per pulse count. Then, the position of the point A at the time of FIG. 7 is obtained by bringing the obtained distance closer to the unmanned forklift 1 side from the position of the point A detected in FIG.
Next, after the point B is detected by the optical sensor 41 in FIG. 6, the distance that the unmanned forklift 1 has advanced from the time when the state shown in FIG. 7 is reached is calculated. This is because the pulse count value of the rotary encoder 17 stored in the storage unit 22 at the time of FIG. 6 and the pulse count value of the rotary encoder 17 stored in the storage unit 22 at the time of FIG. It is obtained by multiplying the travel distance of the unmanned forklift 1 per pulse count. Then, the position of the point B at the time of FIG. 7 is obtained by bringing the obtained distance closer to the unmanned forklift 1 side from the position of the point B detected in FIG.
[0039]
As a result, two positions of points A and B at the time of FIG. 7 are obtained, and three positions are obtained together with the position of the point C detected by the limit switch 42 at the time of FIG. .
The work center position calculation unit 23 calculates the center position Or of the work W at the time shown in FIG. 7 from the positions of these three points (A point, B point, and C point). At this time, information on the arrangement positions of the optical sensor 41 and the limit switch 42 on the vehicle stored in advance in the storage unit is used. As a calculation method of the center position Or of the workpiece W, a known method is used in which the center of a circle passing through the given three points is obtained. For example, a vertical bisector of points A and B and a vertical bisector of points A and C may be obtained, and the intersection of two vertical bisectors may be set as the center position Or.
The workpiece center position calculation unit 23 notifies the determination unit 24 of the information on the center position Or of the workpiece W thus obtained.
[0040]
The determination unit 24 calculates the amount of positional deviation (distance G shown in FIG. 7) between the position of the center position Or of the workpiece W and the center position Oi of the workpiece W at the ideal gripping position. The center position Oi at the ideal gripping position of the workpiece W is determined in advance by experiments or the like and stored in the storage unit 22.
When the positional deviation amount G is within a predetermined range that is predetermined in an experiment or the like and stored in the storage unit 22, the determination unit 24 appropriately grasps the workpiece W by the clamp arms 5 and 6. Judge that it is possible. If it is out of the range, it is determined that the clamp arms 5 and 6 cannot properly grip the workpiece W.
The determination unit 24 notifies the determination result to the arm control unit 25.
[0041]
When the determination unit 24 determines that the clamp arms 5 and 6 can properly hold the workpiece W, the arm control unit 25 extends the cylinder 7 and closes the clamp arms 5 and 6. Grip.
On the other hand, when the determination unit 24 determines that the clamp arms 5 and 6 cannot properly grip the workpiece W, the cylinder 7 is not driven, the gripping operation is stopped, and the position of the workpiece W is abnormal. A signal to that effect is transmitted to the host device.
[0042]
As described above, the unmanned forklift 1 according to the present embodiment performs the gripping operation of the clamp arms 5 and 6 after the determination unit 24 determines that the workpiece W is properly gripped by the clamp arms 5 and 6. Therefore, it is possible to avoid a trouble caused by forcibly grasping the work W even though the work W is largely displaced, and the work efficiency is excellent.
In addition, the determination by the determination unit 24 is also the center position of the workpiece W calculated by the workpiece center position calculation unit 23 based on the detected positions of the three edges (point A, point B, point C) of the workpiece W. Since it is determined from Or, for example, an image sensor that acquires the contour of the edge of the workpiece W as an image is provided, and the position of the workpiece W is detected as compared with a configuration in which the obtained image is processed to obtain the center position. Therefore, the sensor configuration can be simplified. In the present embodiment, a simple sensor configuration in which one optical sensor 41 and one limit switch 42 are provided can be realized.
[0043]
Further, the determination unit 24 shifts the position difference between the center position Or of the workpiece W obtained by the workpiece center position calculation unit 23 and the center position Oi of the ideal gripping position that is determined in advance and stored in the storage unit 22. The amount G is calculated, and whether or not the clamp arms 5 and 6 can properly grip the workpiece W is determined based on whether or not the amount of positional deviation G is within a predetermined value.
Accordingly, it is easy to determine whether or not the workpiece W can be properly gripped by the clamp arms 5 and 6, and the processing capability required of the determination unit 24 can be reduced, so that the electrical configuration can be reduced in cost and the determination can be made. The time required can be shortened.
[0044]
Further, in the present embodiment, the edge of the workpiece W is detected by a non-contact type optical sensor 41 and a limit switch 42. Among these, the optical sensor 41 is located at one place (in FIG. 5). A point (point A) and a point passing through the workpiece W (point B in FIG. 6) and two edges of the workpiece W are detected.
Therefore, since the two places of the edge of the workpiece | work W can be detected with the one optical sensor 41, the structure of a sensor can be simplified and cost can be reduced.
[0045]
Further, in the present embodiment, the non-contact type optical sensor 41 is provided almost on the machine center line, whereas the contact type limit switch 42 is provided on the short arm 5 which is located on the left side of the machine center line. It is attached to the tip. In other words, the optical sensor 41 is disposed on the unmanned forklift 1 with respect to the limit switch 42 while having a shift in the left-right direction of the machine body (a shift p shown in FIG. 2B).
For example, if the two sensors 41 and 42 are mounted side by side in the longitudinal direction of the machine body, the unmanned forklift 1 can be detected only at two locations by simply moving the unmanned forklift 1 straight on the workpiece W. Thus, the center position Or of the workpiece W cannot be calculated. Accordingly, it is necessary to cause the optical sensor 41 to scan in the left-right direction of the machine body, or to cause the unmanned forklift 1 to enter the work W obliquely.
In this respect, in the present embodiment, the two sensors 41 and 42 are arranged with a displacement p in the left-right direction of the machine body. Therefore, the edge of the workpiece W can be moved by simply moving the unmanned forklift 1 straight toward the workpiece. Three points A point, B point, and C point can be detected, and sufficient information for calculating the center position of the workpiece W by the workpiece center position calculation unit 23 can be obtained. Therefore, the configuration of the sensor can be simplified also by this.
[0046]
Furthermore, in this embodiment, the unmanned forklift 1 is stopped at the timing when the contact type limit switch 42 detects the edge of the workpiece W, and the center position of the workpiece W is calculated at this position. Since the point C detected by the limit switch 42 that detects contact with the edge is directly detected, the accuracy of the detected position is high. Therefore, according to the configuration of the present embodiment in which the center position Or of the workpiece W is calculated using the position information of the point C detected by the contact-type limit switch 42, the accuracy of the center position Or obtained as a calculation result is high. Since the height is high, the determination by the determination unit 24 as to whether or not the clamp arms 5 and 6 can be properly gripped can be accurately and accurately performed.
[0047]
In this embodiment, the unmanned forklift 1 is stopped at the timing when the contact-type limit switch 42 detects the edge of the workpiece W, and the clamping arm 5 or 6 is held at this position. The clamp arms 5 and 6 can be closed by rotating the long arm 6 while directly confirming that the workpiece W is in contact with the tip of the workpiece 5 with the limit switch 42 as a contact sensor.
That is, since the sensor for detecting the edge of the workpiece W includes the contact-type limit switch 42 attached to the short arm 5 on the fixed side of the clamp arms 5 and 6, the short on the fixed side. A gripping mode is realized in which the contact of the arm 5 with the workpiece W is directly confirmed by the limit switch 42 and then sandwiched by the long arm 6 on the movable side, so that a gripping error of the workpiece W is more reliably avoided.
[0048]
Note that the positional deviation amount G calculated by the determination by the determination unit 24 is a positional deviation amount in the longitudinal direction of the aircraft as shown in FIG. 7 in the present embodiment, but is not limited to this. For example, the positional deviation amount in the left-right direction of the body may be calculated, or the distance between two points between the actual center Or of the workpiece W and the center Oi of the ideal gripping position may be simply used as the positional deviation amount. I do not care.
[0049]
[Second Embodiment]
Next, a second embodiment shown in FIG. 8 will be described. In the second embodiment, the sensor for detecting the edge of the workpiece W is configured by only a non-contact sensor.
In the unmanned forklift 1 ′ of the second embodiment, as shown in FIG. 8, the limit switch 42 attached to the short arm 5 in the first embodiment is removed, and instead, the bar 12 is branched from the middle. The branch portion 12b is formed, and the same sensor (non-contact type second photosensor) 42 ′ as the photosensor 41 is attached to the tip of the branch portion 12b. In this configuration, if the optical sensor 41 detects the points A and B and the second optical sensor 42 ′ detects the point C, respectively, the workpiece center position calculation unit 23 performs the same as in the configuration of FIG. The center position Or of the workpiece W can be calculated.
[0050]
The configuration of the second embodiment is a configuration in which the edge of the workpiece W is detected by the two non-contact sensors 41 and 42 ′. Therefore, the contact of the limit switch 42, which is a problem in the above-described limit switch 42. There is an advantage that damage to the workpiece W due to direct contact with the workpiece W can be surely avoided.
[0051]
Even in the configuration of the second embodiment, the second optical sensor 42 'is attached to the optical sensor 41 while having a displacement p in the left-right direction of the machine body, whereby the first embodiment of FIG. Similarly to the above, it is possible to detect the three positions of the edge of the workpiece W simply by moving the unmanned forklift 1 ′ straightly toward the workpiece W.
[0052]
Furthermore, in the configuration of the second embodiment, before the workpiece W comes into contact with the clamp arms 5 and 6, the two optical sensors 41 and 42 'located in front of the clamp arms 5 and 6 are used to The edge can be detected at three locations. Accordingly, the center position of the workpiece W can be calculated by the workpiece center position calculation unit 23 at a time before the workpiece W comes into contact with the clamp arms 5 and 6.
If this center position is used, it is possible to predict by calculation the center position Or of the workpiece W when the unmanned forklift 1 ′ advances straight and the short arm 5 contacts the workpiece W. If the determination unit 24 determines the amount of deviation between the calculated predicted center position Or and the ideal gripping position Oi, the unmanned forklift 1 ′ is kept as it is before the workpiece W comes into contact with the clamp arms 5 and 6. It is possible to determine in advance whether or not it can be properly held by the clamp arms 5 and 6 when it is moved straight.
That is, the configuration of the second embodiment is a configuration capable of determining at an early stage whether or not the workpiece W can be properly gripped by the clamp arms 5 and 6, and is further excellent in work efficiency.
[0053]
Or the sensor for detecting the edge of the workpiece | work W can also be comprised by three non-contact sensors. This configuration is shown as an unmanned forklift 1 ″ of the third embodiment shown in FIG.
In the third embodiment of FIG. 9, in the configuration of the second embodiment, one branch portion 12 b is further formed from the middle of the bar 12, and the third photosensor 43 is attached to the tip thereof. Then, if the light sensor 41 detects the point A, the second light sensor 42 ′ detects the point B, and the third light sensor 43 detects the point C, the workpiece can be detected in the same manner as in the configuration of FIG. The center position calculation unit 23 can calculate the center position Or of the workpiece W.
Even in the configuration of the third embodiment, each of the optical sensors 41, 42 ′, 43 is attached to the other optical sensors while having the displacements p1, p2 in the left-right direction of the machine body. There is an advantage that the three positions of the edge of the workpiece W can be detected simply by moving "" straight toward the workpiece W.
[0054]
In the three embodiments described above, the non-contact type optical sensor 41 (42 ', 43) is attached in front of the tip of the clamp arms 5 and 6. Accordingly, it is possible to detect the edge of the workpiece W until the vehicle advances toward the workpiece W and the clamp arms 5 and 6 and the main body of the unmanned forklift 1 reach the position of the workpiece W. As a result, a series of operations until the unmanned forklift 1 moves forward toward the workpiece W and stops at the gripping position can be performed smoothly. For example, in the first embodiment, the deceleration control of the traveling motor 16 is started at the timing when the optical sensor 41 detects the point B, and the control for reducing the impact when the short arm 5 contacts the workpiece W is achieved. Yes.
In the case of an unmanned forklift that attaches a clamp arm to the rear part of the vehicle and approaches the workpiece W while moving backward, the optical sensor may be attached at a position closer to the rear than the clamp arm.
[0055]
Although the present embodiment relates to an unmanned forklift, the application of the present invention is not hindered as long as it is a cargo handling vehicle that automatically loads and unloads loads.
[0056]
As the non-contact type sensor, other non-contact type sensors such as a magnetic sensor may be used instead of the direct reflection type optical sensor 41.
[0057]
Further, the work W may be placed not on the pallet 30 of the self-propelled carriage 32 but on the traveling surface of the unmanned forklift 1, for example, when there is no movable object on the lower side.
[0058]
The clamp arms 5 and 6 may have the same length as each other or may be rotatable together.
[0059]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0060]
That is, 1st invention In the unmanned cargo handling vehicle provided with a clamp arm that can be opened and closed for gripping a cylindrical workpiece from both sides in the radial direction, a workpiece edge detection means for detecting at least three edge portions of the workpiece Each of the three locations was detected by the travel distance detecting means for detecting the travel distance of the vehicle itself, the placement position of the work edge detecting means on the vehicle, and the work edge detecting means. A workpiece center position calculating means for calculating a center position of the workpiece at the time of a gripping operation of the clamp arm, at least using a traveling distance of the vehicle sometimes detected by the traveling distance detection means; and the workpiece center position calculation Determining means based on the center position of the workpiece calculated by the means for determining whether or not the clamp arm can properly grip the workpiece; When the lamp arm said determination means determines that it is possible to properly grip the workpiece, is operated in a direction to close the clamp arm is provided with the, and clamping arm control means,
After confirming that the workpiece is properly gripped by the clamp arm, the clamp arm is gripped, so troubles caused by forcibly gripping the misaligned workpiece can be avoided in advance. Excellent efficiency.
In addition, since the workpiece edge detection means only needs to detect three edges of the workpiece, the configuration of the sensor can be simplified.
[0061]
Second invention As shown in FIG. 4, the determination means calculates a positional deviation amount between the current center position of the work calculated by the work center position calculation means and a predetermined optimum center position. Since it is determined that the clamp arm is in a state in which the workpiece can be properly gripped when the amount of positional deviation is within a predetermined value,
Since it is easy to determine whether or not the workpiece can be properly gripped by the clamp arm, and the processing capability required for the determination means is small, the electrical configuration can be reduced in cost and the time required for determination can be shortened. .
[0062]
Third invention As shown in FIG. 4, the sensor that constitutes the workpiece edge detection means includes a non-contact type sensor, and the non-contact type sensor is configured to detect two edges of the workpiece with one sensor. Because
The configuration of the sensor of the workpiece edge detection means can be simplified, and the cost can be reduced.
[0063]
4th invention As shown in FIG. 2, the workpiece edge detection means is composed of a plurality of sensors, and at least one of the plurality of sensors has a deviation in the left-right direction of the machine body relative to the other sensors on the vehicle. Because it is arranged
The configuration of the sensor of the workpiece edge detection means can be simplified. Further, the edge of the workpiece can be detected at a plurality of locations simply by moving the vehicle straight toward the workpiece.
[0064]
5th invention As shown in FIG. 2, the clamp arm is composed of a movable arm and a fixed arm, and the sensor constituting the workpiece edge detection means includes a contact sensor attached to the fixed arm. ,
The position of the edge detected by the contact type sensor can increase the accuracy of the detection position because the detection is direct by the contact type. Accordingly, by using this to calculate the center position of the workpiece by the workpiece center position calculating means, the center position can be calculated with high accuracy. As a result, it is possible to accurately and accurately determine whether or not the clamp arm can be properly gripped by the determining means.
[0065]
6th invention As shown in the above, the sensor constituting the workpiece edge detection means is only a non-contact type sensor,
The damage of the workpiece due to the contact of the contact sensor contacting the workpiece for detection can be surely avoided.
[0066]
7th invention As shown in FIG. 4, the sensor constituting the workpiece edge detection means includes one or a plurality of non-contact type sensors, and at least one of the non-contact type sensors is provided by the clamp arm. Is also attached to the position closer to the workpiece,
It is possible to detect the edge of the workpiece before the clamp arm or the vehicle body comes into contact with the workpiece. As a result, a series of operations until the cargo handling vehicle advances straight toward the workpiece and stops at the gripping position can be smoothly performed.
[Brief description of the drawings]
FIG. 1 is an overall side view of an unmanned forklift according to a first embodiment of the present invention.
2A is a partial side view showing a state in which an unmanned forklift grips a workpiece at a holding position, and FIG. 2B is a partial plan view of the same.
FIG. 3 is a block diagram showing an electrical configuration of an unmanned forklift.
FIG. 4 is a plan view showing a state in which an unmanned forklift starts to advance straight toward a workpiece.
FIG. 5 is a plan view showing a state in which the optical sensor reaches the work and detects the first position (point A) of the edge of the work.
FIG. 6 is a plan view showing a state in which the optical sensor passes through the workpiece and detects the second position (point B) on the edge of the workpiece.
FIG. 7 is a plan view showing a state in which a limit switch comes into contact with a workpiece and detects a third position (point C) on the edge of the workpiece.
FIG. 8 is a partial plan view showing an unmanned forklift according to a second embodiment.
FIG. 9 is a partial plan view showing an unmanned forklift according to a third embodiment.
[Explanation of symbols]
1 Unmanned forklift (unmanned cargo handling vehicle)
5 Short arm (fixed arm, clamp arm)
6 Long arm (movable arm, clamp arm)
23 Work Center Position Calculation Unit (Work Center Position Calculation Means)
24 Judgment Unit (Judgment Means)
25 Arm control unit (clamp arm control means)
41 optical sensor (non-contact type sensor, workpiece edge detection means)
42 Limit switch (contact sensor, workpiece edge detection means)
W Work

Claims (4)

In an unmanned cargo handling vehicle provided with a clamp arm that can be opened and closed to grip a cylindrical workpiece from both sides in the radial direction,
A workpiece edge detection means for detecting at least three edges of the workpiece;
Mileage detection means for detecting the mileage of the vehicle itself;
At least the position of the workpiece edge detection means on the vehicle, and the vehicle travel distance detected by the travel distance detection means when each of the three locations is detected by the work edge detection means. Using a workpiece center position calculating means for calculating a center position of the workpiece at the time of gripping operation of the clamp arm;
Determining means for determining whether or not the clamp arm can properly grip the work based on the center position of the work calculated by the work center position calculating means;
Clamp arm control means for operating the clamp arm in a closing direction when the determination means determines that the clamp arm can properly grip the workpiece;
Equipped with a,
The workpiece edge detection means can detect whether or not there is an object at a predetermined height in a downward direction at a position closer to the workpiece than the clamp arm while having a deviation in the lateral direction of the machine body. Consists of a plurality of non-contact sensors attached,
The non-contact type sensor is configured to pass above the edge of the workpiece before the clamp arm comes into contact with the workpiece when the vehicle goes straight toward the workpiece, so that the edge of the workpiece is at least An unmanned cargo handling vehicle characterized by detecting three locations .   An unmanned cargo handling vehicle according to claim 1,
  The workpiece edge detection means is composed of two non-contact sensors,
  At least one of the two non-contact sensors is configured to pass above the workpiece before the clamp arm contacts the workpiece when the vehicle travels straight toward the workpiece. An unmanned cargo handling vehicle that detects two edges of a workpiece.   An unmanned cargo handling vehicle according to claim 2,
  An unmanned cargo handling vehicle comprising: a control unit configured to control the vehicle to decelerate from a point in time when two positions of the edge of the workpiece are detected by the sensor that detects two positions of the edge of the workpiece. . An unmanned cargo handling vehicle according to any one of claims 1 to 3 ,
The determination means calculates a positional deviation amount between the center position of the workpiece calculated by the workpiece center position calculation means and a predetermined center position, and the obtained positional deviation amount is within a predetermined range. An unmanned cargo handling vehicle characterized by determining that the clamp arm can appropriately grip the workpiece by being inside.

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