Material handling vehicles

Abstract

To provide a loading vehicle capable of surely clamping a columnar load.SOLUTION: A loading vehicle comprises: a vehicle body 11; a traveling drive unit; a steering drive unit; a roll clamp device 36 that has a pair of clamp arms 38 and 39 capable of gripping a columnar load W; and a controller 29 that controls the traveling drive unit, the steering drive unit, and the roll clamp device 36. An object detector is provided, which can detect the load W and the tips of the clamp arms 38 and 39. The controller 29 acquires a virtual line passing through the abutting position of the clamp arm 38 and the axial center of the load W on the basis of detection by the object detector, estimates an intersection point between the center locus of the tip of the clamp arm 39 and the outer peripheral edge of the load W, controls the traveling drive unit and the steering drive unit so that the intersection point can approach an opposite point which is an intersection point with the outer peripheral edge opposite to the abutting position at the virtual line, and moves the position of the vehicle body 11.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This invention relates to a material handling vehicle equipped with a roll clamping device capable of clamping a cylindrical load.

Background Art

[0002] As a conventional technique of a material handling vehicle, for example, a roll clamping device disclosed in Patent Document 1 is known. In the roll clamping device disclosed in Patent Document 1, a clamp holder having a pair of opposed short arms and swing arms is disposed on the front surface of a base mounted on a forklift via a clamp position correcting device. The clamp position correcting device is composed of a guide bracket having an arcuate guide groove centered on the mounting axis of the short side clamp pad, a guide rod that moves along the guide groove, and a hydraulic cylinder as a drive source. Therefore, by rotating the clamp holder with the short side clamp pad in contact with the roll paper, the contact position of the swing side clamp pad with respect to the roll paper can be corrected. That is, according to this type of roll clamping device, after one clamp arm is brought into contact with the roll paper, the contact position of the other clamp arm with respect to the roll paper can be corrected and moved without accompanying vehicle operation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, when clamping cylindrical loads such as rolls of paper using a roll clamping device, the efficiency of the work depends on the skill of the operator of the material handling vehicle equipped with the roll clamping device. Furthermore, in unmanned operation where the operator does not operate the device, it is necessary to contact the clamp arm at the appropriate position on the load. However, with the roll clamping device disclosed in Patent Document 1, the operator must determine whether or not the clamp arm is contacting the outer edge of the roll of paper at the appropriate position. Moreover, it is difficult to clamp cylindrical loads in unmanned operation with the roll clamping device disclosed in Patent Document 1.

[0005] This invention has been made in view of the above-mentioned problems, and the object of this invention is to provide a material handling vehicle capable of reliably clamping cylindrical loads. [Means for solving the problem]

[0006] To solve the above problems, the present invention provides a cargo handling vehicle having a vehicle body equipped with drive wheels and steering wheels, a driving unit mounted on the vehicle body that drives the drive wheels, a steering drive unit that steers the steering wheels, a mast provided at the front of the vehicle body, a roll clamp device that is movable up and down relative to the mast and has a pair of clamp arms capable of gripping cylindrical loads, and a controller that controls the driving drive unit, the steering drive unit, and the roll clamp device, wherein the load and the tips of the pair of clamp arms can be detected. The device is equipped with an object detector, and the controller, when the tip of one of the pair of clamp arms contacts the outer surface of the load, acquires a virtual line passing through the contact position of the one arm and the axis of the load based on the detection by the object detector, estimates the intersection point of the central trajectory of the tip of the other arm of the pair of clamp arms and the outer edge of the load, and controls the driving unit and the steering unit so that the intersection point approaches the opposite point, which is the intersection point of the outer edge on the virtual line that is opposite to the contact position, thereby moving the position of the vehicle body.

[0007] The present invention includes an object detector capable of detecting cylindrical loads and the tips of a pair of clamping arms. When the tip of one of the pair of clamping arms contacts the outer surface of the load, the controller obtains a virtual line passing through the contact position of one arm and the axis of the load based on the detection by the object detector, and estimates the intersection point of the center trajectory of the tip of the other arm of the pair of clamping arms and the outer edge of the load. The controller then controls the driving unit and steering unit so that the intersection point approaches the opposite point, which is the intersection point of the outer edge opposite to the contact position on the virtual line, and moves the position of the vehicle body. As a result, the cargo handling vehicle can reliably clamp cylindrical loads.

[0008] Furthermore, in the above-described cargo handling vehicle, the object detector may be a camera, and the vehicle may be configured to include an image processing unit that processes the camera image captured by the camera. In this case, the controller can estimate the contact position of the tip of the other arm on the outer edge of the cylindrical load by processing the camera image captured by the camera using the image processing unit.

[0009] Furthermore, in the above-mentioned cargo handling vehicle, the camera may be configured to be mounted on the upper part of the mast. In this case, by mounting the camera on the top of the mast, the camera can more easily capture images of the outer edge of the cylindrical load when the pair of clamping arms clamp it. Therefore, the controller can detect when one of the arms contacts the outer surface of the load by processing the camera images.

[0010] Furthermore, in the above-described cargo handling vehicle, the controller may be configured to estimate the intersection point based on the detection by the object detector when one of the arms comes into contact with the load. In this case, when one arm contacts a cylindrical load, the controller estimates the intersection point between the central trajectory of the tip of the other arm and the outer edge of the load based on the detection by the object detector. Therefore, when one arm makes contact, the controller can estimate the contact position of the tip of the other arm and determine whether the tip of the other arm is in an appropriate position for clamping the load. [Effects of the Invention]

[0011] According to the present invention, a material handling vehicle capable of securely clamping cylindrical loads can be provided. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of a forklift according to an embodiment of the present invention. [Figure 2] This is a side view of a forklift according to an embodiment of the present invention. [Figure 3] This is a plan view of a forklift according to an embodiment of the present invention. [Figure 4] This is a schematic diagram of a forklift according to an embodiment of the present invention. [Figure 5] (a) is a plan view of a forklift with the clamp arm in an improper position, and (b) is a plan view of a forklift with the clamp arm in a proper position. [Figure 6] This flowchart illustrates the control procedure by the controller for properly clamping the load using the clamp arm. [Modes for carrying out the invention]

[0013] Hereinafter, a forklift as a cargo handling vehicle according to an embodiment of the present invention will be described with reference to the drawings. The forklift of this embodiment is a roll clamp lift equipped with a roll clamp device as an attachment capable of clamping cylindrical rolls of paper as cargo. The directions "front and back," "left and right," and "up and down" are indicated based on the state in which the forklift operator is seated in the driver's seat of the driver's cab and facing the forward direction of the forklift. Incidentally, the forklift of this embodiment is capable of both unmanned and manned operation.

[0014] As shown in Figures 1 and 2, the forklift 10 has a mast 12 at the front of the body 11. A driver's seat 13 is located near the center of the body 11. Drive wheels 14 are located at the front of the body 11, and steering wheels 15 are located at the rear of the body 11. A counterweight 16 is located at the rear of the body 11, and the counterweight 16 is used to adjust the vehicle weight and balance the weight of the body 11. A driver's seat 17 is located in the driver's seat 13. An instrument panel 18 is located in front of the driver's seat 17. A steering wheel 20 is located on the instrument panel 18 via a steering column 19. As shown in Figure 3, the instrument panel 18 is equipped with several load handling levers, including a lift lever 21, a tilt lever 22, a rotation lever 23, and a clamp lever 24. An accelerator pedal 25 and a brake pedal 26 are located near the floor of the driver's seat 13.

[0015] The vehicle body 11 is equipped with an engine 27 as a traveling drive unit, and the rotational force of the engine 27 is transmitted to the drive wheels 14 via a driving force transmission mechanism (not shown), whereby the forklift 10 travels. Further, the vehicle body 11 is equipped with a steering drive unit 28 for steering the steering wheel 15. The vehicle body 11 is equipped with a controller 29 for controlling each part. As shown in FIG. 4, the controller 29 controls the engine 27 and also controls the steering drive unit 28. The controller 29 is connected to a roll clamp device 36 and a stereo camera 50, which will be described later.

[0016] The controller 29 includes a CPU (not shown) as an arithmetic processing unit and a storage unit (not shown) composed of a RAM, a ROM, etc. The controller 29 may include dedicated hardware for executing at least a part of various processes, for example, an application specific integrated circuit (ASIC). The controller 29 can be configured as a circuit including one or more processors that operate according to a computer program, one or more dedicated hardware circuits such as an ASIC, or a combination thereof.

[0017] The vehicle body 11 is provided with a head guard 30 that covers the upper part of the driver's seat 13. A tilt cylinder 31 that operates with hydraulic oil is installed between the vehicle body 11 and the mast 12. The mast 12 tilts in the front-rear direction with the lower end of the mast 12 as a fulcrum by the operation of the tilt cylinder 31. In manned operation, the tilt cylinder 31 is operated by the operation of the operator's tilt lever 22.

[0018] The mast 12 has an outer mast 32 and an inner mast 33 (see FIGS. 1 and 3). A pair of left and right outer masts 32 are provided with a pair of left and right inner masts 33 that can move up and down inside the outer masts 32. The inner mast 33 moves up and down by the operation of a lift cylinder 34 provided on the outer mast 32. During manned travel, the lift cylinder 34 moves up and down by the operation of the operator's lift lever 21. The mast 12 is provided with a lift bracket 35 that moves up and down along the inner mast 33, and a roll clamping device 36 is rotatably provided on the lift bracket 35.

[0019] The roll clamping device 36 includes an arm holder 37, and clamp arms 38 and 39. The arm holder 37 includes a rotating portion 40 that rotates about a horizontal axis, and a mounting portion 41 provided on the rear side of the vehicle for mounting to the lift bracket 35. A pair of clamp arms 38 and 39 are attached to the rotating portion 40 of the arm holder 37. For this reason, the clamp arms 38 and 39 that clamp the cylindrical load W can rotate about a horizontal axis and move up and down in the extending direction of the mast 12. The cylindrical load W is, for example, a roll of paper.

[0020] The pair of clamp arms 38 and 39 are composed of a short arm 38 which is one of the clamp arms and a long arm 39 which is the other clamp arm. The base ends of the short arm 38 and the long arm 39 are attached to the rotating portion 40 of the arm holder 37 via a mounting shaft 43. The clamp arms 38 and 39 can be opened and closed in the direction of gripping the load W by a clamp cylinder 42. In the present embodiment, the short arm 38 is fixed to the rotating portion 40, and the long arm 39 is rotatably attached to the mounting shaft 43 of the arm holder 37 by the clamp cylinder 42. The pair of clamp arms 38 and 39 can clamp the load W by the rotation of the long arm 39. In the present embodiment, although the short arm 38 is fixed to the arm holder 37, the short arm may be made rotatable by providing a clamp cylinder on the short arm.

[0021] A clamp pad 44 is rotatably mounted on the tip of the short arm 38 via a pin 45. A clamp pad 46 is rotatably mounted on the tip of the long arm 39 via a pin 45. The clamp pads 44 and 46 are mounted so as to swing around the pin 45 provided on the tips of the clamp arms 38 and 39, in accordance with the load received from the load W, so that the clamp arms 38 and 39 can easily generate gripping force when gripping the load W. A pad stopper 48 is attached to the clamp pad 44 to restrict the swinging, and a pad stopper 49 is similarly attached to the clamp pad 46. The clamping surfaces of the clamp pads 44 and 46 that come into contact with the load W are curved so as to conform to the outer circumference of the cylindrical load W.

[0022] Incidentally, the forklift 10 of this embodiment is equipped with a stereo camera 50 as an object detector in order to more appropriately clamp the cylindrical load W. The stereo camera 50 has a pair of left and right cameras 51 and 52. The right camera 51 is mounted on the upper part of the right outer mast 32, and the left camera 52 is mounted on the upper part of the left outer mast 32. The right camera 51 and the left camera 52 are mounted facing slightly downward and forward so as to capture the tips of the clamp arms 38 and 39. The right camera 51 and the left camera 52 are monocular cameras, and the combination of the right camera 51 and the left camera 52 constitutes the stereo camera 50. Incidentally, the right camera 51 and the left camera 52 may each be a compound stereo camera.

[0023] The stereo camera 50 is connected to a controller 29, which acts as an image processing unit (see Figure 4). Through image processing of the camera images by the controller 29, the controller 29 recognizes the center positions of the clamp pads 44 and 46, as well as the contour of the upper end of the outer surface of the load W. The controller 29 also recognizes the center trajectory of the pin 45 of the clamp pad 46 as the long arm 39 rotates.

[0024] As shown in Figures 5(a) and 5(b), in this embodiment, the axis P is defined as the center of the vertically positioned load W in a plan view. The trajectory traced by the center of the clamp pad 46 due to the rotation of the long arm 39 is defined as the central trajectory T, and the point where the outer edge of the load W intersects with the central trajectory T is defined as the intersection point Q. Furthermore, a virtual line M is defined as a virtual line passing through the contact position of the short arm 38 on the outer edge of the load W and the axis P. Incidentally, the contact position of the short arm 38 on the outer edge of the load W is specifically the center of the clamp pad 44 (the axis of the pin 45). Furthermore, the point on the outer edge opposite to the contact position of the short arm 38 on the virtual line M is defined as the opposite point R, and the distance between the intersection point Q and the opposite point R is defined as the distance S.

[0025] As shown in Figure 5(a), when the forklift 10 attempts to clamp the load W with a pair of left and right clamping arms 38 and 39, the short arm 38 is brought into contact with the load W first. As shown in Figure 5(b), when the forklift 10 clamps the load W with the clamping arms 38 and 39, it is most desirable that the intersection point Q coincides with the opposite point R of the imaginary line M connecting the center of the clamping pad 44 and the axis P.

[0026] Therefore, the controller 29 estimates the intersection point Q based on image processing of the camera image from the stereo camera 50 when the tip of the short arm 38 of the pair of clamp arms 38, 39 contacts the outer surface of the load W. In this embodiment, the controller 29 estimates the intersection point Q at the timing when the tip of the short arm 38 contacts the outer surface of the load W. The controller 29 then controls the engine 27 and the steering drive unit 28 to move the position of the vehicle body 11 so that the intersection point Q approaches the opposite point R. In addition, the controller 29 may estimate the intersection point Q in the image processing at the timing just before the tip of the short arm 38 contacts the outer edge of the load W.

[0027] Figure 6 is a flowchart showing the control procedure by the controller 29 for properly clamping the load W with the clamp arms 38 and 39. When the forklift 10 clamps the load W with the pair of clamp arms 38 and 39, the controller 29 moves the vehicle body 11 so that the forklift 10 approaches the load W (step S01). This is achieved by the controller 29 issuing commands to the engine 27 and the steering drive unit 28 for control. While the forklift 10 is in operation, the stereo camera 50 constantly captures images of the clamp arms 38 and 39, and the captured camera images are processed by the controller 29. When the vehicle body 11 moves, the forklift 10 approaches the load W so that the short arm 38 makes contact with the load W first.

[0028] Next, the controller 29 determines whether the short arm 38 has come into contact with the load W (step S02). Whether the short arm 38 has come into contact with the load W is detected by image processing of the camera image, and the controller 29 makes this determination from the detection result obtained by image processing. When it is determined that the short arm 38 has come into contact with the load W, the controller 29 stops the forward movement of the vehicle body 11 (step S03). Next, the controller 29 obtains a virtual line M passing through the center of the clamp pad 44 of the short arm 38 and the axis P (step S04). The outer edge of the load W is a circle in plan view, and the controller 29 identifies the axis P based on image processing of the camera image. The virtual line M can be obtained by image processing from the center of the clamp pad 44 and the identified axis P. On the other hand, if the short arm 38 is not in contact with the load W in step S02, the controller 29 continues the movement of the vehicle body 11.

[0029] When the controller 29 acquires a virtual line M in step S04, it estimates the intersection point Q between the central trajectory T of the long arm 39 and the outer edge of the load W (step S05). The outer edge of the load W is detected based on image processing of the camera image. When the controller 29 estimates the intersection point Q between the central trajectory T of the long arm 39 and the outer edge of the load W in step S05, it determines whether the distance S between the opposite point R on the virtual line M and the intersection point Q is less than or equal to a threshold (step S06). The threshold for the distance S between the opposite point R and the intersection point Q is set so that the clamp arms 38 and 39 can properly clamp the load W.

[0030] In step S06, if it is determined that the distance S between the opposite point R and the intersection point Q of the virtual line M is less than or equal to a threshold, the controller 29 stops changing the attitude of the vehicle body 11 (step S07). When the distance S between the opposite point R and the intersection point Q is less than or equal to a threshold, the clamp arms 38 and 39 are in a state where they can properly clamp the load W. Therefore, after stopping the change in the attitude of the vehicle body 11 or if the attitude of the vehicle body 11 has not been changed, the controller 29 starts operating the long arm 39 (step S08). The clamping of the load W is completed when the clamp arms 38 and 39 clamp the load W (step S09).

[0031] In step S06, if it is determined that the distance S between the virtual line M and the axis P of the load W is not below a threshold, the controller 29 starts moving the vehicle body 11 to change its attitude (step S10). Specifically, the change in the attitude of the vehicle body 11 is a rotation of the vehicle body 11 with the contact position of the short arm 38 as the pivot point, so that the intersection point Q approaches the opposite point R. Once the attitude of the vehicle body 11 is changed, the controller returns to step S05 and estimates the intersection point Q between the central trajectory T of the long arm 39 and the outer edge of the load W again. The controller 29 repeats the loop from step S10 through steps S05 and S06 until the distance S between the opposite point R and the intersection point Q is below a threshold, that is, until the intersection point Q approaches the opposite point R.

[0032] Next, the operation of the forklift 10 of this embodiment in clamping a cylindrical load W will be described. The load W to be clamped by the forklift 10 is placed vertically. When the forklift 10 clamps the load W, it moves forward toward the load W by unmanned operation. The stereo camera 50 captures images of the tips of the clamp arms 38 and 39, and the controller 29 processes the captured camera images.

[0033] For example, as shown in Figure 5(a), when the short arm 38 contacts the outer surface of the load W, the controller 29 determines, based on image processing, that the short arm 38 has contacted the load W and stops the forklift 10 from moving forward. Contact between the short arm 38 and the outer surface of the load W is determined by detecting, through image processing, that the clamp pad 44 of the short arm 38 has contacted the outer edge of the circular load W in a plan view.

[0034] The controller 29 obtains a virtual line M passing through the center of the clamp pad 44 of the short arm 38 (the axis of the pin 45) and the axis P of the load W in a plan view, and identifies the opposite point R, which is the opposite endpoint of the clamp pad 44 on the virtual line M. The controller 29 also estimates the intersection point Q of the center trajectory T of the clamp pad 46 of the long arm 39 and the outer edge of the load W when the short arm 38 contacts the outer surface of the load W in a plan view. The controller 29 determines whether the distance S between the intersection point Q and the opposite point R is below a threshold.

[0035] In the state shown in Figure 5(a), the distance S between intersection Q and opposite point R exceeds a threshold, so the controller 29 controls the engine 27 and steering drive unit 28 to move the vehicle body 11 so that intersection Q approaches opposite point R, thereby changing the attitude of the vehicle body 11. Specifically, with the short arm 38 in contact with the load W, the vehicle body 11 is rotated counterclockwise around the center of the clamp pad 44 as the pivot point. As shown in Figure 5(b), it is permissible for the load W to move relative to the road surface when the vehicle body 11 rotates.

[0036] During rotation, the controller 29 repeatedly performs discrimination based on image processing until the distance S between the intersection point Q and the opposite point R falls below a threshold. In the state shown in Figure 5(b), the intersection point Q and the opposite point R almost coincide in the image processing, so the distance S between the intersection point Q and the opposite point R is below the threshold, and the controller 29 stops changing the attitude of the vehicle body 11. Next, the controller 29 rotates the long arm 39 in the clamping direction. As the long arm 39 rotates, the clamp pad 46 comes into contact with the load W, and the pair of clamp arms 38 and 39 clamp the load W. Since the intersection point Q and the opposite point R almost coincide, the clamp arms 38 and 39 securely clamp the load W.

[0037] With the clamp arms 38 and 39 clamping the load W, the forklift 10 can move by raising the lift bracket 35. Also, by rotating the roll clamp device 36 relative to the lift bracket 35, the orientation of the clamp arms 38 and 39 can be changed, making it possible to change the orientation of the load W from vertical to horizontal.

[0038] The forklift 10 of this embodiment provides the following effects. (1) The forklift has an object detector capable of detecting the cylindrical load W and the tips of a pair of clamp arms 38 and 39. When the tip of the short arm 38 contacts the outer surface of the load W, the controller 29 acquires a virtual line M passing through the contact position of the short arm 38 and the axis P of the load W based on the detection by the object detector, and estimates the intersection point Q of the central trajectory T of the tip of the long arm 39 and the outer edge of the load W. The controller 29 then controls the engine 27 and the steering drive unit 28 so that the intersection point Q approaches the opposite point R, which is the intersection point of the outer edge opposite to the contact position on the virtual line M, thereby changing the attitude of the vehicle body 11. As a result, the forklift 10 can reliably clamp the cylindrical load W. As a result, it is possible to prevent the load W from falling off the clamp arms 38 and 39 when the load W is clamped by the roll clamp device 36. Furthermore, since the vehicle body 11 stops moving when the distance S between intersection point Q and opposite point R falls below a threshold, there is no need to readjust the vehicle body 11's posture to properly adjust it for clamping the load W, thus improving the efficiency of cargo handling operations.

[0039] (2) The object detector is a stereo camera 50 and has a controller 29 as an image processing unit that processes the camera images captured by the stereo camera 50. Therefore, by processing the camera images captured by the stereo camera 50 with the image processing unit, the controller 29 can detect the contact positions of the pair of short arms 38 on the outer edge of the cylindrical load W based on the detection by the stereo camera 50. It can also estimate the intersection point Q between the central trajectory T of the tip of the long arm 39 and the outer edge of the load W.

[0040] (3) The stereo camera 50 is mounted on the top of the mast 12. As a result of mounting the stereo camera 50 on the top of the mast 12, when the pair of clamping arms 38 and 39 clamp the cylindrical load W, the stereo camera 50 can capture images of the outer edge of the load W. As a result, the controller 29 can detect when the short arm 38 comes into contact with the outer surface of the load W by processing the camera images.

[0041] (4) When the short arm 38 comes into contact with the cylindrical load W, the controller 29 estimates the intersection point Q of the central trajectory T of the tip of the long arm 39 and the outer edge of the load W based on the detection by the stereo camera 50. Therefore, when the short arm 38 comes into contact with the cylindrical load W, the controller 29 estimates the contact position of the tip of the long arm 39 on the outer edge of the load W based on the camera image from the stereo camera 50. Therefore, when the short arm 38 comes into contact with the load, the controller 29 can determine whether the tip of the long arm 39 is in an appropriate position for clamping the load W by estimating the intersection point Q of the central trajectory T of the tip of the long arm 39 and the outer edge of the load W.

[0042] (5) When the short arm 38 contacts the load W, the contact position of the tip of the long arm 39 on the outer edge of the load W is estimated. Therefore, the accuracy of the estimation of the contact position of the long arm 39 is higher compared to when it is estimated at the timing just before the tip of the short arm 38 contacts the outer edge of the load W.

[0043] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the invention. For example, the following modifications may be made.

[0044] ○ In the above embodiment, a stereo camera was used as an example to describe the object detector, but it is not limited to this. The object detector may be, for example, a laser distance sensor. When the object detector is a laser distance sensor, the contact position of the tip of one of the pair of clamp arms and the intersection point of the center trajectory of the tip of the other arm and the outer edge of the load can be estimated based on the detection of point cloud data of laser light by the laser distance sensor. Note that when the object detector is a camera, it is not limited to a stereo camera, but may be, for example, a monocular camera. ○ In the above embodiment, the object detector is provided on the mast, but this is not limited to this. The object detector may be provided on the head guard, for example. In this case, by providing the object detector on the head guard via a bracket, the load and the tips of the clamp arms can be appropriately detected. Also, in the above embodiment, an example of providing the object detector on the outer mast was described, but the object detector may be provided on the inner mast. By providing the object detector on the inner mast, the tips of the pair of clamp arms can be detected even when the clamp arms are in a raised position. ○ In the above embodiment, a forklift capable of unmanned driving and loading / unloading was used as an example of a loading / unloading vehicle, but it is not limited to this. The loading / unloading vehicle may also be a manned forklift operated by an operator. In the case of a manned forklift, the operator can change the vehicle's posture from the point where the short arm makes contact with the load. In this case, the operator refers to the camera image and changes the vehicle's posture so that the intersection point of the central trajectory of the tip of the other arm and the outer edge of the load approaches the opposite point on a virtual line passing through the contact position of one arm and the axis of the load. The controller then notifies the operator by sounding a buzzer or lighting a lamp when the distance between the intersection point and the opposite point on the virtual line falls below a threshold. As a result, the pair of clamping arms can be operated by the operator to reliably clamp the load in the optimal position. ○ In the above embodiment, a controller was used as an example to describe the image processing unit, but the invention is not limited to this. For example, the image processing unit may be provided separately from the controller, and the image processing unit may be connected to the controller. ○ In the above embodiment, contact between the load and one arm was detected based on image processing of the camera image, but this is not limited to this. For example, a sensor may be provided at the tip of one arm, and the sensor may detect contact between the load and one arm. [Explanation of symbols]

[0045] 10 Forklifts 11 Car body 12 Mast 13. Driver's seat 14 drive wheels 15 Steering Wheel 27. Engine (driving unit) 28 Steering drive unit 29. Controller (Image Processing Unit) 32 Outer Mast 33 Inner Mast 35 Lift Bracket 36 Roll clamping device 38. Clamp Arm (Short Arm) 39. Clamp Arm (Long Arm) 44 Clamp Pad (Short Arm) 45 pins 46 Clamp Pad (Long Arm) 50 Stereo cameras (object detectors) 51 Right camera 52 Left camera M virtual line P center axis Q intersection R Opposition S distance T center locus W load

Claims

1. A vehicle body equipped with drive wheels and steering wheels, A drive unit mounted on the vehicle body that drives the drive wheels, A steering drive unit that steers the steering wheel, A mast is provided at the front of the vehicle body, A roll clamp device having a pair of clamp arms that are movable up and down relative to the mast and capable of gripping cylindrical loads, In a cargo handling vehicle having the aforementioned driving unit, steering unit, and controller for controlling the roll clamp device, It has an object detector capable of detecting the load and the tips of the pair of clamp arms, The controller, when the tip of one of the pair of clamp arms contacts the outer surface of the load, acquires a virtual line passing through the contact position of the one arm and the axis of the load based on the detection by the object detector, estimates the intersection point of the central trajectory of the tip of the other arm of the pair of clamp arms and the outer edge of the load, and controls the driving unit and the steering unit so that the intersection point approaches the opposite point, which is the intersection point of the outer edge on the virtual line opposite to the contact position, thereby moving the position of the vehicle body.

2. The object detector is a camera capable of imaging the tip portions of the pair of clamp arms. The cargo handling vehicle according to claim 1, characterized in that it has an image processing unit that processes the camera image captured by the aforementioned camera.

3. The cargo handling vehicle according to claim 2, characterized in that the camera is installed on the upper part of the mast.

4. The cargo handling vehicle according to claim 1 or 2, characterized in that the controller estimates the intersection point based on the detection of the object detector when one of the arms comes into contact with the load.

Images