JP7468228B2 - crane - Google Patents

Description

The present invention relates to a crane.

Conventionally, cranes such as mobile cranes, crawler cranes, tower cranes, gantry cranes, and overhead cranes are known. Cranes are capable of transporting loads suspended from a hook.

Incidentally, there is known a crane equipped with a camera on the trolley that photographs a marker attached to a hook or the like (see Patent Documents 1 and 2). Such a crane can detect the position of the hook or the cargo based on the image captured by the camera. However, even if this technical idea is applied to a crane used outdoors, there are cases where the position of the hook or the cargo cannot be detected due to the influence of disturbance light such as sunlight. On the other hand, when the image is captured through a filter that transmits the irradiated light of the wavelength emitted by the marker so as not to be influenced by such disturbance light, the image does not show the objects other than the marker, and therefore it is not possible to obtain a monitoring image of the area captured by the camera. Therefore, there has been a demand for a crane that can accurately detect the position of the hook or the cargo based on the image captured by the camera without being influenced by disturbance light, and can obtain a monitoring image of the area captured by the camera.

JP 2017-522248 A Japanese Patent Application Laid-Open No. 11-189393

To provide a crane that can accurately detect the position of a hook or a load based on an image captured by a camera without being affected by ambient light, and can also obtain a surveillance image of the area captured by the camera.

The first invention is
A crane that transports a load with the load suspended from a hook,
A marker attached to the hook or the luggage and emitting irradiation light of a predetermined wavelength;
A filter that transmits the marker's illuminating light;
a camera that captures an image including the marker through the filter with a predetermined exposure time;
a control device for processing the image,
The predetermined exposure time is
a first exposure time for capturing an image used to detect the position of the marker;
a second exposure time longer than the first exposure time for capturing an image used to monitor an area including the marker;
The control device is configured to obtain images captured by the camera by repeatedly alternating between the first exposure time and the second exposure time.

The second invention is a crane according to the first invention,
The control device includes:
setting a reference point on the object captured in the image captured with the second exposure time;
Tracking the reference point located at a position at least a predetermined distance away from the marker;
Calculating an amount of shake of the image captured with the second exposure time based on the amount of movement of the tracked reference point;
The image shake is corrected in accordance with the calculated amount of image shake.

The third invention is a crane according to the second invention,
The control device corrects the position of the marker in accordance with the calculated amount of image shake.

The fourth invention is a crane according to the second or third invention,
The tracked reference point is a reference point provided on a feature on the ground.

The fifth invention is a crane according to any one of the first to fourth inventions,
The marker uses an infrared light emitting diode as a light source,
The filter is an infrared transmission filter that transmits the light emitted from the infrared light emitting diode.

In the crane according to the first invention, the control device acquires images captured by the camera by repeatedly alternating between a first exposure time and a second exposure time. With such a crane, an image showing only the marker is captured during the first exposure time, and an image showing luggage and other items other than the marker is captured during the second exposure time. Therefore, the position of the hook or luggage can be accurately detected based on the image captured by the camera without being affected by ambient light, and a monitoring image of the area captured by the camera can be acquired.

In the crane according to the second invention, the control device sets a reference point on the object to be photographed in the image captured with the second exposure time, and tracks the reference point located at a position at least a predetermined distance away from the marker. Then, the control device calculates the amount of shake of the image captured with the second exposure time based on the amount of movement of the tracked reference point, and corrects the image shake according to the calculated amount of image shake. With such a crane, it is possible to calculate the amount of image shake using a stationary object located at a position away from the hook or cargo as a reference. Therefore, image shake caused by camera movement relative to the stationary object can be accurately corrected.

In the crane according to the third invention, the control device corrects the position of the marker according to the calculated amount of image shake. With such a crane, the position of the marker is detected without the influence of image shake. Therefore, the position of the hook or the cargo can be detected with high accuracy.

In the crane according to the fourth invention, the reference point to be tracked is a reference point set on a feature. With such a crane, the amount of image blur is calculated based on the feature, which is a stationary object. Therefore, image blur caused by the camera moving relative to the stationary object can be accurately corrected.

In the crane according to the fifth invention, the marker uses an infrared light emitting diode as a light source, and the filter is an infrared transmission filter that transmits the light emitted by the infrared light emitting diode. With such a crane, the image capture with the first exposure time is not affected by sunlight, which is an external disturbance light. Therefore, the position of the hook or the load can be detected with high accuracy.

A diagram showing a crane. FIG. 13 shows a marker attached to a hook. A diagram showing the radiant emittance and irradiance of solar radiation. A diagram showing the interior of the cabin. FIG. 2 is a diagram showing a control configuration of a crane. 1A is a diagram explaining images captured by a camera; FIG. 1A is a diagram explaining how the camera alternates between short exposure and long exposure; FIG. 1B is a diagram showing an image captured by a short exposure; and FIG. 1C is a diagram showing an image captured by a long exposure. 1A and 1B are diagrams explaining the correction of image shake, in which (a) is a diagram showing a long-exposure image before the camera shakes, (b) is a diagram showing a long-exposure image while the camera is shaking, and (c) is a diagram showing a long-exposure image with shake corrected. 1A and 1B are diagrams for explaining correction of marker positions; FIG. 1A shows an image captured with a short exposure before the camera is vibrated; and FIG. 1B shows an image captured with a short exposure while the camera is vibrating. FIG. 4 is a flowchart showing a short-time exposure process. FIG. 4 is a flowchart showing a long exposure process. FIG. 13 shows a marker attached to luggage.

The technical ideas disclosed in this application can be applied to other embodiments in addition to the embodiments described below.

First, a crane 1 according to one embodiment will be described with reference to FIG. 1. In this application, the crane 1 will be described as a mobile crane, but the invention can also be applied to other types of cranes that transport loads by hanging them from a hook. Examples of other types of cranes include crawler cranes, tower cranes, gantry cranes, and overhead cranes.

The crane 1 is mainly composed of a running body 2 and a rotating body 3.

The running body 2 is equipped with a pair of left and right front wheels 21 and rear wheels 22. The running body 2 is also equipped with outriggers 23 that are grounded to provide stability when transporting cargo L. The running body 2 is capable of freely rotating the rotating body 3 supported on its upper part by an actuator.

The rotating body 3 is equipped with a boom 31 that protrudes forward from its rear. Therefore, the boom 31 is freely rotatable by an actuator (see arrow A). The boom 31 is also freely extendable and retractable by an actuator (see arrow B). Furthermore, the boom 31 is also freely raiseable and lowerable by an actuator (see arrow C).

In addition, a wire rope 32 is stretched across the boom 31. A hook 33 is attached to the wire rope 32 that hangs down from the tip of the boom 31. A winch 34 is disposed near the base end of the boom 31. The winch 34 is configured integrally with an actuator, and allows the wire rope 32 to be wound in and out. Therefore, the hook 33 can be raised and lowered by the actuator (see arrow D). The rotating body 3 is equipped with a cabin 35 on the side of the boom 31. Inside the cabin 35, a rotating lever 61, a telescopic lever 62, a hoisting lever 63, a winding lever 64, etc. are provided (see FIG. 4).

Next, the marker 40 attached to the hook 33 will be described with reference to Figures 2 and 3.

The marker 40 emits light of a predetermined wavelength. In this embodiment, the marker 40 is attached to the side of the hook 33. The attachment position of the marker 40 is not limited. Therefore, the marker 40 may be attached to the luggage L instead of the hook 33 (see FIG. 11).

The marker 40 has a rectangular shape when viewed from above. The marker 40 has multiple light-emitting devices 41 embedded in its upper surface and is covered with a transparent resin material. These light-emitting devices 41 are supplied with electricity from a battery 43 arranged below the marker 40 via a driver 42 arranged below the marker 40. The driver 42 can adjust the flow of electricity based on predetermined conditions. The battery 43 is a so-called primary battery, but it may also be a secondary battery that can store electricity from a solar panel or the like.

In this way, a dot pattern is drawn on the upper surface (imaged surface) of the marker 40 by the light-emitting devices 41. The dot pattern is composed of, for example, nine light-emitting devices 41 arranged at predetermined positions. In this embodiment, the light-emitting devices 41 use infrared light-emitting diodes as the light source. The infrared light-emitting diodes emit light with a wavelength of approximately 940 nm ("approximately 940 nm" means that the peak wavelength is in the range of 940 nm ±5%). The arrangement and number of the light-emitting devices 41 are not particularly limited, and it is sufficient that the position and orientation of the marker 40 can be detected based on the image of the light-emitting devices 41.

Solar radiation has a characteristic spectral distribution (see Figure 3). Solar radiation is mainly composed of ultraviolet rays below about 400 nm, visible light from about 400 nm to about 700 nm, and infrared rays above about 700 nm. The radiant emittance of solar radiation, which indicates the amount of energy emitted, is maximum at about 500 nm. Furthermore, the radiant emittance of solar radiation decreases rapidly as the wavelength becomes shorter from about 500 nm, and decreases more gradually as the wavelength becomes longer from about 500 nm (see the thick line T in the figure).

Since the Earth is covered by the atmosphere, energy is absorbed before it reaches the Earth's surface. For this reason, the irradiance of solar radiation, which indicates the amount of energy on the irradiated side, is maximum at approximately 500 nm. Furthermore, the irradiance of solar radiation decreases rapidly as the wavelength becomes shorter from approximately 500 nm, and decreases gradually as the wavelength becomes longer from approximately 500 nm (see the thin line t in the figure). In addition, it is known that the amount of energy absorbed by the atmosphere increases or decreases depending on the wavelength. This is due to the components in the atmosphere. For example, at 940 nm ± 5%, the amount of energy absorbed increases significantly due to water vapor in the atmosphere (see the ta section in the figure).

That is, sunlight, which is the main disturbance light, has a significantly reduced irradiance at 940 nm ±5%. Therefore, by emitting irradiance light using an infrared light-emitting diode with a wavelength of approximately 940 nm as a light source and selectively capturing this irradiance light, the effects of disturbance light on the captured image can be suppressed. Note that the wavelength of the irradiance light is not limited to approximately 940 nm, and other wavelengths at which the irradiance is reduced may also be used (for example, see parts tb and tc in the figure).

Next, the control configuration of the crane 1 will be explained using Figures 4 and 5.

The crane 1 is equipped with a control device 50. The control device 50 is connected to various levers 61 to 64. In addition, the control device 50 is connected to various valves 71 to 74.

As described above, the boom 31 is rotatable by an actuator (see arrow A in FIG. 1). In this application, this actuator is defined as a rotation motor 36 (see FIG. 1). The rotation motor 36 is operated appropriately by a rotation valve 71, which is a directional control valve. The rotation valve 71 is operated based on the operation of the rotation lever 61 by the operator. The rotation angle and rotation speed of the boom 31 are detected by a sensor (not shown).

The boom 31 can be extended and retracted by an actuator (see arrow B in Figure 1). In this application, this actuator is defined as a telescopic cylinder 37 (see Figure 1). The telescopic cylinder 37 is operated appropriately by a telescopic valve 72, which is a directional control valve. The telescopic valve 72 is operated based on the operation of the telescopic lever 62 by the operator. The telescopic length and telescopic speed of the boom 31 are detected by a sensor (not shown).

The boom 31 can be raised and lowered by an actuator (see arrow C in Figure 1). In this application, this actuator is defined as a hoisting cylinder 38 (see Figure 1). The hoisting cylinder 38 is operated appropriately by a hoisting valve 73, which is a directional control valve. The hoisting valve 73 is operated based on the operation of the hoisting lever 63 by the operator. The hoisting angle and hoisting speed of the boom 31 are detected by a sensor (not shown).

Furthermore, the hook 33 can be raised and lowered by an actuator (see arrow D in Figure 1). In this application, this actuator is defined as a winding motor 39 (see Figure 1). The winding motor 39 is operated appropriately by a winding valve 74, which is a directional control valve. The winding valve 74 is operated based on the operation of the winding lever 64 by the operator. The hanging length and lifting speed of the hook 33 are detected by a sensor (not shown).

In addition, a camera 65, an inclinometer 67, and a display 75 are connected to the control device 50. A filter 66 is attached to the camera 65 (see Figure 1).

The camera 65 photographs the work site of the crane 1 from above. The camera 65 is attached to the tip of the boom 31 so that it can capture an image including the marker 40 from directly above (see FIG. 1). The camera 65 is also connected to the control device 50. Therefore, the control device 50 can obtain an image including the marker 40.

Since the camera 65 is suspended from the tip of the boom 31, it oscillates like a pendulum when the crane 1 is operating or when wind blows toward the camera 65. The boom 31 itself also vibrates, causing the position and orientation of the camera 65 to change. When the camera 65 moves in this way during shooting, this causes the captured image to shake. The control device 50 can hold the images captured by the camera 65 for a specified time. In other words, even if the camera 65 moves, the control device 50 can acquire all images in the vibration shooting range G0, which is the range captured by the camera 65 while moving, within the specified time (see vibration shooting range G0 in FIG. 7).

The camera 65 captures an image at a set predetermined exposure time. The predetermined exposure time consists of a first exposure time and a second exposure time longer than the first exposure time. Hereinafter, exposure at the first exposure time is called a short exposure, and exposure at the second exposure time is called a long exposure. The camera 65 can capture images by alternating between short exposure and long exposure. In the short exposure, an image used to detect the position of the marker 40 is captured. The position of the marker 40 is a three-dimensional position including the height of the marker 40 above the ground. In addition, in the long exposure, an image (monitoring image) used to monitor the area including the marker 40 is captured. The area including the marker 40 is, for example, the area of the work site of the crane 1 including the hook 33 and the luggage L. The camera 65 is set to a frame rate of 60 fps for shooting, for example. When the camera 65 alternates between short exposure and long exposure, the frame rate for each is 30 fps, which is sufficient for a video. For example, when the first exposure time is set to 0.1 ms and the second exposure time is set to 2 ms, the camera 65 can capture an image in a time that is sufficiently short for the frame rate described above. This allows the camera 65 to capture images in real time at the frame rate described above. Note that the frame rate, the first exposure time, and the second exposure time are not limited to the values described above.

Filter 66 transmits the light emitted from marker 40. Filter 66 is attached to camera 65 so that camera 65 can take an image through filter 66. In this embodiment, filter 66 is an infrared transmission filter that transmits the light emitted from an infrared light emitting diode. The infrared transmission filter has a transmission wavelength of 940 nm band ("940 nm band" means a range of 940 nm ± 15% regardless of the transmittance (more preferably 940 nm ± 5%) considering the amount of energy absorption by the atmosphere mentioned above).

The inclinometer 67 detects the angle of the camera 65. The inclinometer 67 is attached to the camera 65 so that it can detect the current attitude angle, which is the current attitude angle of the camera 65 with respect to the vertical direction. The inclinometer 67 is also connected to the control device 50. Therefore, the control device 50 can recognize the current attitude angle.

The display 75 displays various images. The display 75 is attached to the front of the driver's seat inside the cabin 35 so that the operator can view it while operating the various levers 61 to 64 (see FIG. 4). The display 75 is also connected to the control device 50. Therefore, the control device 50 can provide information to the operator through the display 75. Specifically, the image captured by the camera 65 during the second exposure time can be displayed within the display range G1 (see FIG. 6(c)). In this embodiment, the display range G1 is the range captured by the camera 65 within a predetermined angle range where the current attitude angle of the camera 65 can be considered to be zero degrees.

Next, the functions of the crane 1 will be described with reference to Figures 6 to 8. For convenience, the display range G1 in Figures 7 and 8 is defined as the X direction in the upward direction on the paper and the Y direction in the rightward direction.

The camera 65 alternates between taking a short-exposure image and a long-exposure image (see FIG. 6(a)). As described above, the marker 40 uses an infrared light-emitting diode as a light source. On the other hand, the camera 65 is equipped with an infrared transmission filter that transmits the light emitted by the infrared light-emitting diode. For this reason, in the short-exposure image, the image Ma taken by the camera 65 shows the dot pattern drawn by the light-emitting device 41 in the dark (see FIG. 6(b)). However, in FIG. 6(b), the brightness has been changed to ensure the clarity of the drawing. On the other hand, in the long-exposure image, the image Mb taken by the camera 65 shows the baggage L and the work site of the crane 1 because the energy of the sunlight in the 940 nm band is not completely absorbed by the water vapor in the atmosphere (see FIG. 6(c)).

The control device 50 acquires a short-exposure image Ma captured by the camera 65. The control device 50 recognizes the dot pattern on the short-exposure image Ma and detects the position and orientation of the marker 40 in real time. Here, the short-exposure image Ma shows only the marker 40. This minimizes the number of objects to be recognized, thereby minimizing the possibility of erroneous recognition and speeding up recognition. In this way, when the marker 40 is attached to the hook 33, the control device 50 can accurately detect the position and orientation of the hook 33 in real time. Also, when the marker 40 is attached to the luggage L, the control device 50 can accurately detect the position and orientation of the luggage L in real time. The detection of the position and orientation of the marker 40 is realized by, for example, image recognition technology using pattern matching, but there is no limit to the type of technology used to realize it.

Similarly, the control device 50 acquires a long-exposure image Mb captured by the camera 65. The control device 50 causes the display 75 to display the long-exposure image Mb, which shows the luggage L and the work site of the crane 1. In this way, the operator can monitor the luggage L and the work site of the crane 1 from the long-exposure image Mb displayed on the display 75.

As described above, the long-exposure image Mb shows the work site of the crane 1. The control device 50 can correct the image shake described above using stationary objects at the work site of the crane 1. This is achieved, for example, by a technique for correcting the shake of the long-exposure image Mb described below, but there is no limit to the type of technique used. The position of the marker 40 is detected in real time based on the short-exposure image Ma.

First, the control device 50 acquires a long-exposure image Mb in the current shooting range G2 in real time (see FIG. 7(a)). The control device 50 then sets a reference point P on the object to be shot in the long-exposure image Mb. The reference point P is a point for tracking the object to be shot in the long-exposure image Mb. This is realized, for example, by image recognition technology using optical flow, but there is no limit to the type of technology used to realize this. When optical flow is used, the reference point P is what is called a feature point, and the feature point is extracted (set) on the object to be shot in the long-exposure image Mb. The feature point can be extracted (set) using a known method, so a description thereof will be omitted here.

The control device 50 acquires the next frame image Mb of the long exposure in the current shooting range G2 in real time (see FIG. 7B). In this embodiment, the long exposure image Mb in FIG. 7B shows a state in which the shooting range of the camera 65 is directed in the -Y direction due to the vibration of the camera 65. The control device 50 tracks the set reference point P and calculates the shake amount J2 of the long exposure image Mb based on the movement amount J1 of the tracked reference point P. In this embodiment, the control device 50 excludes the reference point P located closer than a predetermined distance F from the marker 40 from the reference point P to be calculated for the movement amount J1. In other words, the control device 50 tracks the reference point P located at a position more than the predetermined distance F from the marker 40. The predetermined distance F is for excluding the reference point P set on the marker 40 and the luggage L, which are moving objects, from the reference point P to be calculated for the movement amount J1, and is set to be greater than the distance from the marker 40 to the outermost end of the luggage L, for example. In this way, the control device 50 can calculate the amount of movement J1 of the reference point P placed on a stationary object such as a feature E. Since the amount of shake J2 of the long-exposure image Mb changes depending on the amount of movement J1 of the reference point P placed on the stationary object, the amount of shake J2 of the long-exposure image Mb is determined by calculating the amount of movement J1 of the reference point P. The amount of movement J1 of the reference point P is calculated, for example, by averaging the amount of movement J1 of each reference point P on the feature E.

The control device 50 uses the calculated shake amount J2 of the long-exposure image Mb to extract the image of the portion of the current shooting range G2 that matches the display range G1 as the matching image Mb1 (see FIG. 6C). In this embodiment, the matching image Mb1 is extracted based on the fact that the current shooting range G2 is shifted by the shake amount J2 in the -Y direction with respect to the display range G1. Meanwhile, the control device 50 extracts the mismatch image Mb2 (light ink portion), which is an image of the portion of the current shooting range G2 that does not match the display range G1, from the image held up until a predetermined time ago. The control device 50 then displays the composite image Mb3, which is the combination of the matching image Mb1 and the mismatch image Mb2, on the display 75. In this way, the control device 50 corrects the shake of the long-exposure image Mb according to the shake amount J2 of the long-exposure image Mb, and can display the long-exposure image Mb with high visibility in real time.

Furthermore, the control device 50 can correct the position of the marker 40 according to the amount of shake J2 of the long-exposure image Mb, as described below. Note that in FIG. 8 as well, the brightness of the short-exposure image Ma is changed to ensure clarity of the drawing.

First, the control device 50 acquires a short-exposure image Ma in the current shooting range G2 in real time (see FIG. 8(a)). Then, the control device 50 recognizes the dot pattern on the short-exposure image Ma and detects the position of the marker 40.

The control device 50 acquires the next frame image Ma of the short-exposure in the current shooting range G2 in real time (see FIG. 8B). In this embodiment, the short-exposure image Ma in FIG. 8B shows a state in which the shooting range of the camera 65 is directed in the -Y direction due to the vibration of the camera 65. The control device 50 recognizes the dot pattern on the short-exposure image Ma and calculates the position of the marker 40. The short-exposure image Ma does not show any shooting objects other than the marker 40, and does not show stationary objects such as the feature E. However, the shake amount J2 of the long-exposure image Mb can be calculated in real time, and it is estimated that the short-exposure image Ma also has the same shake as the long-exposure image Mb. Therefore, the control device 50 corrects the position of the marker 40 by the shake amount J2 of the long-exposure image Mb and detects the corrected position of the marker 40 in real time. In this way, the control device 50 can improve the accuracy of detecting the position of the hook 33 when the marker 40 is attached to the hook 33. Furthermore, when the marker 40 is attached to the luggage L, the accuracy of detecting the position of the luggage L is improved.

Next, the flow of processing by the control device 50 will be described with reference to Figures 9 and 10. Note that the control device 50 alternately repeats the short-time exposure processing performed from STEP-110 and the long-time exposure processing performed from STEP-210.

First, let's explain short-time exposure processing.

In step S110, the control device 50 acquires the short-exposure image Ma captured by the camera 65 and transitions to step S120.

In step S120, the control device 50 detects the position of the marker 40 based on the short-exposure image Ma, and transitions to step S130.

In step S130, the control device 50 corrects the position of the marker 40 according to the shake amount J2 of the long-exposure image Mb, and transitions to step S140.

In step S140, the control device 50 outputs the position of the hook 33 to which the marker 40 is attached or the luggage L, and ends the short-time exposure process.

Next, we will explain long exposure processing.

In step S210, the control device 50 acquires a long-exposure image Mb captured by the camera 65 and transitions to step S220.

In step S220, the control device 50 sets a reference point P on the subject in the long-exposure image Mb and transitions to step S230.

In step S230, the control device 50 tracks a reference point P located at a position at least a predetermined distance F away from the marker 40, and transitions to step S240.

In step S240, the control device 50 calculates the amount of shake J2 of the long-exposure image Mb based on the amount of movement J1 of the tracked reference point P, and transitions to step S250.

In step S250, the control device 50 corrects the shake of the long-exposure image Mb according to the shake amount J2 of the image Mb, and then proceeds to step S260.

In step S260, the control device 50 outputs the shake-corrected long-exposure image Mb and ends the long-exposure process.

In step S130, the position of the marker 40 is corrected using the shake amount J2 of the long-exposure image Mb calculated in step S240 of the immediately preceding long-exposure process. In step S230, the reference point P to be tracked is determined using the position of the marker 40 corrected in step S130 of the immediately preceding short-exposure process.

Finally, we will summarize the technical ideas and effects disclosed in this application.

That is, in the crane 1, the control device 50 acquires images captured by the camera 65 by repeatedly alternating between a first exposure time and a second exposure time. With this crane 1, an image Ma showing only the marker 40 is captured during the first exposure time, and an image Mb showing the luggage L and other items other than the marker 40 is captured during the second exposure time. Therefore, without being affected by ambient light, the position of the hook 33 or the luggage L can be accurately detected based on the image Ma captured by the camera 65, and a monitoring image of the area captured by the camera 65 can be acquired. In other words, a single camera 65 can accurately detect the position of the hook 33 or the luggage L, and a monitoring image of the area captured by the camera 65 can be acquired.

In addition, in the crane 1, the control device 50 sets a reference point P on the object to be photographed in the image Ma photographed with the second exposure time, and tracks the reference point P located at a position at least a predetermined distance F away from the marker 40. Then, based on the movement amount J1 of the tracked reference point P, the control device 50 calculates the amount of shake J2 of the image Mb photographed with the second exposure time, and corrects the shake of the image Mb according to the calculated amount of shake J2 of the image Mb. With this crane 1, it is possible to calculate the amount of shake J2 of the image Mb based on a stationary object located at a position away from the hook 33 or the cargo L. Therefore, the shake of the image Mb caused by the movement of the camera 65 relative to the stationary object can be accurately corrected.

Furthermore, in the crane 1, the control device 50 corrects the position of the marker 40 according to the calculated amount of shake J2 of the image Mb. With this crane 1, the position of the marker 40 is detected without being affected by the shake of the image Ma. Therefore, the position of the hook 33 or the cargo L can be detected with high accuracy.

Furthermore, in the crane 1, the reference point P to be tracked is a reference point P set on the feature E. With this crane 1, the amount of shake J2 of the image Mb is calculated based on the feature E, which is a stationary object. Therefore, the shake of the image Mb caused by the movement of the camera 65 relative to the stationary object can be accurately corrected.

Furthermore, in the crane 1, the marker 40 uses an infrared light emitting diode as a light source, and the filter 66 is an infrared transmission filter that transmits the light emitted by the infrared light emitting diode. With this crane 1, the image Ma is not affected by sunlight, which is disturbing light, when captured with the first exposure time. Therefore, the position of the hook 33 or the luggage L can be detected with high accuracy.

1 Crane 33 Hook 40 Marker 50 Control device 65 Camera 66 Filter E Feature F Predetermined distance J1 Distance of reference point J2 Image shake amount Ma Image (image captured with first exposure time)
Mb Image (image taken with the second exposure time)
L Baggage P Reference point

Claims (5)

A crane that transports a load with the load suspended from a hook,
A marker attached to the hook or the luggage and emitting irradiation light of a predetermined wavelength;
A filter that transmits the marker's illuminating light;
a camera that captures an image including the marker through the filter with a predetermined exposure time;
a control device for processing the image,
The predetermined exposure time is
a first exposure time for capturing an image used to detect the position of the marker;
a second exposure time longer than the first exposure time for capturing an image used to monitor an area including the marker;
The control device acquires images captured by the camera by alternately repeating the first exposure time and the second exposure time. The control device includes:
setting a reference point on the object captured in the image captured with the second exposure time;
Tracking the reference point located at a position at least a predetermined distance away from the marker;
Calculating an amount of shake of the image captured with the second exposure time based on the amount of movement of the tracked reference point;
2. The crane according to claim 1, wherein the image shake is corrected in accordance with the calculated amount of image shake. The crane according to claim 2, characterized in that the control device corrects the position of the marker according to the calculated amount of image shake. The crane according to claim 2 or 3, characterized in that the tracked reference point is a reference point set on a feature. The marker uses an infrared light emitting diode as a light source,
The crane according to any one of claims 1 to 4, characterized in that the filter is an infrared transmission filter that transmits light emitted by the infrared light emitting diode.

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