EP2574587B1 - Method for determining a target position for a container spreader and the container spreader - Google Patents

Description

In growing global trade, container logistics make significant contributions. It is characterized by constantly increasing efficiency through more and more automation. Many container terminals are highly automated with the help of cranes.

Loading cranes are used on freight transhipment sites, storage areas, in assembly halls and shipyards as well as in track construction. In a loading crane for motor vehicles, the floor is inclined relative to the loading crane, so that water can drain. Furthermore, tracks for trucks are marked on the ground under the loading crane. One embodiment of a loading crane is a gantry crane. This spans a loading and working area like a portal. As a rule, its sidewalls with wheels run on two parallel rails. On the crane bridge, the horizontal part of the gantry crane, a trolley moves with a hoist. Alternatively, a rail slewing crane can be mounted on the crane bridge. Furthermore come as a loading crane and a bridge crane, a half-gantry crane, a gantry crane and a portal crane into consideration.

A container harness (English term "spreader") is a hoist, with which ISO-standardized containers can be taken. It is known both a rigid container dishes, which is intended only for a container size, as well as a telescoping container dishes whose several tons heavy telescopic frame can be flexibly adjusted to the length of different standardized containers (standard sizes 20'-45 '). For further consideration, the maximum height of a "high-cube" container of 2,896 m is especially relevant.

Gantry trucks, gantry forklifts, forklifts or cross-forklifts can also be equipped with a container harness. The container harness is also here an attachment whose so-called twist locks engage in the four upper standardized corner fittings of a container or grab them from the side. In this case, an element of the twistlock is rotated by 90 °, whereby a positive connection is ensured for locking. The size of the twistlocks is standardized and is about 104 mm in length and 56 mm in width.

Frequent operations in container logistics involve anchoring a container to the container harness with which the container is subsequently moved, as well as anchoring the containers to rail wagons or loading areas of trucks. Today, these tasks are handled exclusively by crane operators, who sometimes sit at remote stations and operate different cranes with the help of video images.

To anchor a container on the back of a truck or train wagons Twistlocks are used again. When placing the container, the standardized corner fittings of the container must be positioned exactly above the twistlocks of the truck or train wagon. The required accuracy for the positioning can be estimated here with 25 mm, the height accuracy is less critical.

From the document "Camera-Assisted Automation of Container Cranes - Potentials, Technologies, Framework Conditions", Jörg Krüger and Mike Neuendorf, 19th International Crane Conference 2011, a camera-based, automatic detection of loading and unloading positions on a truck is known. These positions are extracted from the images of high-resolution cameras mounted at height on a trolley of a container crane. This corner fittings of the container and Twistlocks the truck beds are detected in the camera images.

From the document "container handlers" available on the Internet under http://www.orlaco.com/container-handlers.htm on 29.09.2011, it is known to mount cameras directly on the container harness, whose images facilitate a driver of a forklift, the To anchor container harness to a container.

From the US 2002/0024598 A1 For example, a method for determining a target position for a container harness is known wherein cameras are mounted on the container harness and determine readings from an environment of the container harness. In this case, three-dimensional data are calculated from the measured values of the cameras and from distance data of a laser rangefinder, from which anchoring positions, in particular positions of corner fittings, can be determined.

From the US 6 124 932 A It is known to expand or narrow a bundle of time-shifted pulsed point lasers during operation of a crane system for adaptive environment detection.

The object is to provide a method for determining a target position for a container harness and a container dishes, with which the frequent anchoring operations of containers are better supported.

This object is achieved by the method for determining a target position for a container harness, wherein at least one imaging sensor is mounted on the container harness and determines measured values from an environment of the container harness. The at least one imaging sensor is a camera. An arithmetic unit forms three-dimensional data from the measured values, from which it determines anchoring positions, in particular positions of twistlocks or corner fittings, and calculates the target position for the container harness from the anchoring positions. The container harness is additionally equipped with at least one laser.

The method is characterized in that the arithmetic unit extracts lines from the measured values, which the laser projects onto a twistlock or a corner fitting. The arithmetic unit determines the anchoring positions from a geometry of the lines.

The container harness is equipped with at least one imaging sensor which is mounted on the container harness and adapted to determine measurements from an environment of the container harness. The imaging sensor is a camera and suitable for determining measured values and set up, from which three-dimensional data can be calculated, from which in turn anchoring positions, in particular positions of twistlocks or corner fittings, can be determined.

The container harness is characterized by a line laser, which is mounted at a defined distance from the at least one imaging sensor on the container and dishes a laser line at a defined angle to a vertical.

The method as well as the container harness provide a reliable solution for the automated positioning of the container harness. Due to the three-dimensional data processing, the accuracy is so high that after positioning, twistlocks can automatically be locked in corner fittings of a container. This allows the automated loading of trucks for road traffic or rail cars, in which the container to be transported must be secured with twist locks on the bed. The positioning of the imaging sensor on the container dishes achieved due to the proximity to the objects to be detected high accuracy and consequently high reliability in positioning. The latter is essential to avoid property damage and personal injury. This is how it becomes possible for the first time to automate the loading and unloading of vehicles with twistlock securing.

The method has the advantage that the lines which the laser projects onto the twistlock or the corner fitting produce a sufficient contrast even in the open air in unfavorable weather conditions such as rain, direct tropical solar radiation or contamination by rust or oil, which is detected by the camera and the extraction of the lines from the measured values is ensured. It is achieved a very robust position detection.

Furthermore, the use of a simple camera has the advantage that it can be selected in a robust design, whereby the required in view of the violent vibrations on the crane and in particular on the container harness mechanical stability is ensured. Also can be expected in these simple and inexpensive components with a long life. This is advantageous because a frequent component change with recalibration in industrial use is out of the question.

In a development of the method, the laser is a line laser, which is mounted at a defined distance from the at least one imaging sensor on the container harness and emits a laser line at a defined angle to a vertical. The container harness is at least partially lowered via at least one twistlock or corner fitting, with the laser line sweeping over the twistlock or corner fitting. The arithmetic unit continuously extracts the laser line from the measured values and determines a 3D contour from the geometry of the laser line as three-dimensional data. Based on the 3D contour, the arithmetic unit recognizes the twistlock or the corner fitting.

This development has the advantage that the line laser is firmly mounted on the container harness and no turning or swivel suspension needed. Also, the line laser itself can be selected in robust design. Both aspects take into account the industrial requirements for the robustness of the sensors.

According to one embodiment, the arithmetic unit calculates a difference image, which consists of the difference of a camera image with the laser line, for extracting the laser line from the measured values is formed with a timely camera image without the laser line.

The calculation of a difference image offers the advantage that interference factors a priori unknown changes in the background due to changing lighting conditions, rust, contamination o.ä. can be turned off, whereby the robustness of the detection is significantly increased.

In a further development, the camera is equipped with a bandpass filter adapted to a wavelength of the laser. The bandpass filter increases the robustness of image recognition in sunlight, since all wavelengths of sunlight are filtered out of the wavelengths of the laser and thus turned off as disturbing factors in the camera image.

According to one embodiment, the container harness at the target position is fully automatically anchored to a container by twist locks of the container harness engage and lock in corner fittings of the container.

In an alternative embodiment, a container anchored to the container harness at the target position is fully automatically anchored to a cargo bed of a truck or railroad car by engaging twist locks of the truck or railcar in corner fittings of the container and locking.

In a development, the container harness is moved to the target position, wherein two movement sections are traversed. In the first movement section, there is visual contact between at least one anchoring position and the imaging sensor. Furthermore, in the first movement section in a control loop, a continuous recalculation of the target position takes place. In the second movement section, there is no visual contact between the anchoring positions and the imaging sensor. Therefore, the last one becomes calculated target position in the second movement section controlled approached.

This development takes into account the fact that the twist locks in the second movement section can be covered by the container itself. Through the training, the target position can be approximated in this situation.

According to one embodiment, at least one stationary sensor determines orientation measured values of an environment of the container harness. An arithmetic unit determines from the orientation measured values an orientation position for the container harness, which is located in the vicinity of the target position. The container harness is maneuvered to the orienting position before the target position is determined. This embodiment speeds up the process by bringing the container harness using the stationary sensors in advance to save time in the orientation position.

In a further development, the container harness is equipped with further sensors, in particular 2D laser scanners, 3D laser scanners, cameras, 3D cameras, strip projection sensors, distance sensors, proximity switches and / or pressure switches. This allows a further increase in the accuracy of the position determination and additional safety during operation.

A crane is designed as a loading crane, gantry crane, bridge crane, semi-portal crane, gantry crane or portal crane, and equipped with the container harness.

In a development, the crane is additionally equipped with stationary sensors, in particular cameras and / or laser scanners, which are mounted on the crane.

The stationary sensors serve to measure (or estimate) the position and position of moving objects, eg a container. Other uses include measuring the position and position of a vehicle or a movable component of the crane itself into consideration. In the context of a loading crane, stationary sensor measurements serve as a basis to signal truck drivers where to stop. Furthermore, due to such measurements, the crane itself can be controlled.

The stationary sensors may for example be composed of one or more of the following elements: a 3D laser scanner, a tiltable 2D laser scanner or a video camera. They are usually mounted in such a way in the structure of the crane that - in the case of a gantry crane - several tracks for trucks or tracks for railroad cars are covered.

The truck is designed as a straddle carrier, portal stacker, forklift or forklift truck and equipped with a container harness according to one of claims 11 to 16.

The computer-readable medium stores a computer program which executes the procedure when it is executed in a computer. The computer program is processed in a computer and executes the procedure.

Figur 1

einen Kran mit stationären Sensoren sowie ein Frachtgut unter dem Kran,

Figur 2

ein Containergeschirr bei der Annäherung an einen Container,

Figur 3

einen Container bei der Annäherung an einen LKW,

Figur 4

ein Containergeschirr, welches mit bildgebenden Sensoren ausgerüstet ist,

Figur 5

Montagepositionen der bildgebenden Sensoren,

Figur 6

eine Ermittlung von Messwerten von einer Umgebung eines Containergeschirrs,

Figur 7

eine Laserlinie, welche neben einem Twistlock verläuft, und

Figur 8

eine Laserlinie, welche über ein Twistlock verläuft.

In the following, embodiments of the invention will be explained in more detail with reference to figures. Show it:

FIG. 1

a crane with stationary sensors and a cargo under the crane,

FIG. 2

a container harness when approaching a container,

FIG. 3

a container approaching a truck,

FIG. 4

a container harness equipped with imaging sensors,

FIG. 5

Mounting positions of the imaging sensors,

FIG. 6

a determination of measured values from an environment of a container harness,

FIG. 7

a laser line that runs next to a twistlock, and

FIG. 8

a laser line, which runs over a twistlock.

FIG. 1 shows a crane 10. On the crane 10 stationary sensors 6 are mounted. Also shown is a cargo 12, for example a container on a truck, which is detected by the stationary sensors 6. Also in FIG. 1 To see wheels 14, with which the crane 10 can be moved on rails. A floor 15 under the crane 10 is inclined, so that water can flow away. On the floor 15 lane markers 13 are attached, which mark tracks for vehicles. On a trolley 4, a container harness 1 is suspended movably. The container harness 1 has Twistlocks 2, which can be used to grip containers.

FIG. 2 shows a container harness 1 when approaching a container 10. Here, twist locks 2 of the container harness 1 must be accurately positioned on standard corner fittings 11 of the container 10.

FIG. 3 shows a container 10 when approaching a loading area 21 of a truck 20. Here, corner fittings 11 of the container 10 must be accurately positioned over twist locks 2 of the truck 20. The container 10 is transported by means of a container harness 1 by a crane.

FIG. 4 shows a container tableware 1, which is equipped with imaging sensors 3. The container harness 1 is deposited on a container 10.

Suitable imaging sensors 3 are all sensors from whose measured values three-dimensional image data can be generated, for example laser scanners or strip projection sensors.

If only simple cameras are used as imaging sensors 3, a reliable detection of the twistlocks by the variety of forms of loading surfaces and twistlocks, which differ by color, rust, dirt, weather, etc., alone technologically very difficult on the basis of the camera image. This hurdle is overcome by the generation of three-dimensional image data.

An arithmetic unit, for example a microprocessor, forms three-dimensional image data from the measured values, from which position it determines anchoring positions, in particular positions of twistlocks or corner fittings. However, the anchorage positions need not be identical to the positions of the twistlocks, but may also be positions of structures that are easy to detect and whose relative position to the twistlock is known. Furthermore, the arithmetic unit calculates a target position for the container harness 1 from the anchoring positions. At the target position, the container harness 1 can, for example, pick up the container 10 or deposit it on a loading area of a truck or train wagon. The twistlocks and corner fittings appear in the three-dimensional image data with a typical 3D contour. This applies to the twistlock in both extended and contracted states.

This type of position determination can take place once or continuously, as long as a Twistlock targeted by the imaging sensor 3 is not covered by the container 10. Under these conditions, the crane can be controlled in a control loop and move the container harness towards the target position. Once the sighted twistlock is obscured by the container 10, however, can The crane only the last piece to the target position controlled (blind) approach.

Stationary sensors mounted on a bridge or trolley of the crane, such as high overhead laser scanners or cameras, allow the approach to the target position to be accelerated by first placing the container harness in an appropriate coarse position or orientation position near the target position the imaging sensor 3 can detect a twistlock at the target position in its local field of view. For example, this local field of view may be 0.5m x 0.5m so that the orientation position determined by the stationary sensors must approach the target position with that accuracy. Also, the stationary sensors and possibly further distance sensors of the container harness 1 have to ensure that there is no collision when approaching the orientation position.

To ensure that at least two twistlocks can be visually detected when the imaging sensors 3 are arranged at all four corners of the container harness 1, it is advisable to choose the orientation position slightly decentered to the presumed target position.

FIG. 5 shows mounting positions of imaging sensors 3 on a container tableware 1 from different perspectives. Partly also Twistlocks 2 of the container harness 1 are visible.

FIG. 6 1 shows a determination of measured values from an environment of a container harness 1. On the left is a frontal view of the container harness 1 and a container 10 suspended thereon, and on the right a side view. Below the respective illustration, a loading area 21 of a truck or train wagon is shown with a twistlock 2, which is located 4 m or 5 m below the container harness 1. An imaging sensor 3, here a simple camera, is mounted with 180mm or 150mm overhang against the container 10 on the container dishes 1. Out FIG. 6 It can be seen that the imaging sensor 3 can detect the twistlock 2 at 4 m or 5 m distance just in its field of view before the twistlock 2 is completely covered by the container 10. The height of the container 10 is assumed to be 2.960m.

In the present embodiment, a line laser 30 is mounted on the front of the container harness 1 and illuminates the loading surface 21 at a known fixed angle to the vertical (the solder through the container harness 1) or to the loading surface 21 with a single laser line. The mounting position on the front of the container harness 1 makes the process independent of size changes of a telescopic frame of the container harness. From the illuminated by the laser line section through the camera image of the imaging sensor 3 three-dimensional data are calculated, for example, absolute metric three-dimensional data.

For this purpose, the container harness is lowered from 5 meters above the loading area 21 to 4 meters height, as in FIG. 6 shown, wherein the laser line sweeps over the loading surface 21. If the container harness 1 is already in a suitable orientation position (see description of Figure 4), in this case, the twistlock 2 is also covered. Consequently, a 3D contour of the twistlock 2 appears in the three-dimensional data. Based on the 3D contour, the twistlock 2 can be unambiguously identified independently of color, rust, rain, etc., since the 3D shape to be searched for is precisely known.

FIG. 7 shows a laser line 31, which runs next to a twistlock 2. The laser line 31 is shown dotted for clarity, but can also be projected in reality as a solid line.

FIG. 8 shows correspondingly a laser line 31, which passes over a twistlock 2, because, for example, as shown in FIG 6 describes the complete twistlock 2 swept over. The laser line 31 is shown dotted for clarity, but can also be projected in reality as a solid line.

The imaging sensor for detecting the laser line 31 is, for example, a common camera, but which is preferably equipped with a band-pass filter adapted to the wavelength of the laser used. As a result, the robustness of the image processing compared to the interference factor sunlight is significantly increased. A particularly narrow band in conjunction with an LED with a narrow spectrum or a monochromatic laser diode is advantageous here. Accordingly suitable lasers are corresponding LEDs or laser diodes, which in principle can emit other patterns than a line, for example a grating. For example, an infrared laser or a red laser can be used. To comply with the laser safety regulations for the human eye, it is advisable to reduce the irradiation times of the laser to a range of a few tens of microseconds each.

A good compromise for the observance of the laser protection determination with simultaneous high radiation density of the laser line 31 for the irradiation of the sunlight is achieved by a 20μs line projection with a 1.35W laser diode. As laser power, a range of 200mW - 300mW is recommended. The imaging sensor in this case must be able to record images with an exposure time of only 20μs. A black and white camera is sufficient for this. In pulsed operation, cooling for the laser may be omitted.

To focus the laser line 31, when using a laser diode Powell lenses or cylindrical lenses are available in order to achieve the narrowest possible laser line 31, which is sharply imaged over a relatively wide depth range of 0.5 m - 1.2 m.

In order to ensure a sufficient contrast of the laser line 31 in front of the image background, even with direct incidence of sunlight, it makes sense to produce a difference image. For this purpose, two images are acquired immediately following one another from the surface to be measured, one image with and the other image without the laser line 31 being recorded. The difference between the two images makes the laser line 31 particularly clear by eliminating the influence of ambient light and other disturbing structures in the image. Subsequently, it is recommended to stretch the gray scale range of the image.

A 3D sensor is mounted directly on the spreader (the container harness) and scans twistlocks or corner fittings of containers in the vicinity of the spreader. From this, the positions of the twistlocks can be calculated, whereby containers can be deposited fully automatically on the loading areas of trucks or train wagons. A particularly cost-effective and robust solution is the use of conventional cameras with a bandpass filter, which is tuned to the wavelength of a line laser and is used to filter the sunlight from the camera image. As the spreader approaches, the line laser passes over the cargo bed, allowing the 3D contours of the twistlocks to be extracted from the camera image. Here, the problems of conventional image processing, which are caused by different colors of twistlocks, pollution by rust and oil, weather, sunlight, etc., elegantly bypassed. The solution is suitable for cranes at container handling sites, but also for straddle carriers, gantry forklifts or forklifts.

The described embodiments, developments and embodiments can be freely combined with each other.

Claims (15)

1. Method for determining a target position for a container spreader (1), at least one imaging sensor (3) being mounted on the container spreader (1) and determining measured values from the surroundings of the container spreader (1),

   - in which the at least one imaging sensor (3) is a camera,

   - in which a computing unit uses the measured values to form three-dimensional data, from which it determines anchoring positions, in particular positions of twist locks (2) or corner fittings (11),

   - in which the computing unit uses the anchoring positions to calculate the target position for the container spreader (1), and

   - in which the container spreader (1) is additionally equipped with at least one laser,

   characterized in that

   - the computing unit extracts lines from the measured values, which lines the laser projects onto a twist lock (2) or a corner fitting (11), and

   - the computing unit determines the anchoring positions from a geometry of the lines.
2. Method according to Claim 1,

   - in which the laser is a linear laser (30), which is mounted on the container spreader (1) at a defined distance from the at least one imaging sensor (3), and emits a laser line (31) at a defined angle to a vertical,

   - in which the container spreader (1) is at least partly lowered over at least one twist lock (2) or corner fitting (11), the laser line (31) sweeping over the twist lock (2) or the corner fitting (11),

   - in which the computing unit continuously extracts the laser line (31) from the measured values and determines a 3-D contour as three-dimensional data from the geometry of the laser line (31), and

   - in which the computing unit detects the twist lock (2) or the corner fitting (11) by using the 3-D contour.
3. Method according to Claim 2,

   - in which the computing unit for extracting the laser line (31) from the measured values calculates a differential image, which is formed from the difference between a camera image with the laser line (31) and a contemporary camera image without the laser line (31).
4. Method according to one of the preceding claims,

   - in which the container spreader (1) is fully automatically anchored on a container (10) at the target position, by twist locks (2) of the container spreader (1) engaging in corner fittings (11) of the container (10) and being locked.
5. Method according to one of Claims 1 to 3,

   - in which a container (10) anchored to the container spreader (1) at the target position is fully automatically anchored on a loading surface of an LGV (20) or railway wagon, by twist locks (2) of the LGV (20) or railway wagon engaging in corner fittings (11) of the container (10) and being locked.
6. Method according to one of the preceding claims,

   - in which the container spreader (1) is moved into the target position, two movement sections being passed through,

   - in which, in the first movement section, there is a visual contact between at least one anchoring position and the imaging sensor (3),

   - in which, in the first movement section, continuous recalculation of the target position is carried out in a control loop,

   - in which, in the second movement section, there is no visual contact between the anchoring positions and the imaging sensor (3), and

   - in which, in the second movement section, the last calculated target position is approached under control.
7. Method according to one of the preceding claims, in which

   - at least one stationary sensor (6) determines orientation measured values from the surroundings of the container spreader (1),

   - a computing unit uses the orientation measured values to determine an orientation position for the container spreader (1), which is located in the vicinity of the target position, and

   - in which the container spreader (1) is manoeuvred into the orientation position before the target position is determined.
8. Container spreader (1),

   - equipped with at least one imaging sensor (3), which is mounted on the container spreader (1) and is set up to determine measured values from the surroundings of the container spreader (1),

   - wherein the at least one imaging sensor (3) is a camera and is suitable and set up to determine measured values, from which three-dimensional data can be calculated, from which in turn anchoring positions, in particular positions of twist locks (2) or corner fittings (11), can be determined,

   characterized in that

   - the container spreader is additionally equipped with a linear laser (30), which is mounted on the container spreader (1) at a defined distance from the at least one imaging sensor (3) and emits a laser line (31) at a defined angle to a vertical.
9. Container spreader (1) according to Claim 8,

   - in which the camera is equipped with a band-pass filter matched to a wavelength of the laser.
10. Container spreader (1) according to either of Claims 8 and 9,

    - equipped with further sensors, in particular 2-D laser scanners, 3-D laser scanners, cameras, 3-D cameras, stripe projection sensors, distance sensors, proximity switches and/or pressure switches.
11. Crane (5),

    - constructed as a loading crane, portal crane, bridge crane, semi-portal crane, gantry crane or slewing portal crane, and

    - equipped with a container spreader (1) according to one of Claims 8 to 10.
12. Crane (5) according to Claim 11,

    - additionally equipped with stationary sensors (6), in particular cameras and/or laser scanners, which are mounted on the crane (5).
13. Industrial truck

    - implemented as a straddle carrier, portal stacker, fork-lift truck or side-loader, and

    - equipped with a container spreader (1) according to one of Claims 8 to 10.
14. Computer-readable data storage medium,

    - on which there is stored a computer program which carries out the method according to one of Claims 1 to 7 when it is executed in a computer.
15. Computer program,

    - which is executed in a computer and carries out the method according to one of Claims 1 to 7.

Images