KR20050007241A - Absolute-position detection method and algorithm of spreader for the auto-landing of containers - Google Patents

Abstract

PURPOSE: A detection method for an absolute position of a spreader and an algorithm thereof are provided to realize the unmanned operation of a navigation equipment by automatically getting a container on and off an AGV(Automatic Guided Vehicle) through a trolley. CONSTITUTION: A size information of a container is inputted, a container approaching is informed to a buffer and a position information of a spreader on a ground is checked(S1). The container is loaded in the spreader on the ground by checking the position information of the spreader on the ground(S2). The spreader is fallen after checking a fixed position of an AGV through a laser displacement sensor in the trolley and a displacement between the spreader and the AGV is measured(S3). A coordinate value of the spreader is measured through a laser scanner(S4). An error range is checked by using the coordinate of the spreader(S5). The coordinate of the spreader is measured again by controlling the position and the movement of the spreader when the error range is not within a corresponding range(S6). In satisfying the error range, the container is loaded in the AGV and the spreader is raised(S7).

Description

Absolute-position detection method and algorithm of spreader for the auto-landing of containers}

The present invention relates to a method for detecting an absolute position of a spreader for automatic landing of a container crane in a container crane. More particularly, when a container is loaded on an AGV vehicle through a container crane, the laser displacement sensor mounted on a trolley and a crane By determining the absolute position of the container landing on the AGV vehicle using a laser scanner mounted on the vertical frame connecting member, it is possible to carry out smooth and accurate loading operation between the AGV vehicle and the container, as well as reduce the risk of safety accidents. The present invention relates to a method and algorithm for detecting an absolute position of a spreader for automatic landing of a container.

A typical container crane is difficult to measure the position of the hanging spreader due to the shaking of the anchored container ship and the long hoist rope, making it difficult to automate or unmanned. In most cases, the container to be recognized is not fixed on the sea side of the container crane due to the shaking of the ship, and it is difficult to measure the position of the container to be recognized due to the surrounding container when directly loading and unloading it from the container ship. Since there is no space to install a sensor for detection, there is a problem that it is difficult to unmanned.

In recent years, however, the volume of imports and exports by sea has increased dramatically as the scale of international logistics has increased. As a result, more than 10,000 TEU-class giant ships have emerged, and the size of the container terminal is growing large enough for large vessels to dock. Thus, the world's advanced ports operate automated and unmanned container terminals and develop new cranes or AGVs to expand existing port functions. Especially, the yard equipment is developed or commercialized for the purpose of full unmanned operation. It is being used in actual port.

Figure 1a or 1b shows an automated terminal using an AGV (Automatic Guided Vehicle) and an unmanned yard crane at the ECT terminal in the Netherlands, in which the AGV is in charge of the function of the yard tractor, the driving of the upper layer You will receive instructions from. There is a need for a system that guides the stop position so that the AGV can drive at high speeds and stop at the correct position within the terminal. This system is called an automatic landing system. This serves as the spreader of the container crane to detect the exact absolute position of the spreader to raise or lower the container onto the AGV or tractor and to automatically correct the position by communication between the AGV and the crane.

As such automatic landing system method, there is a method of using a laser sensor and a method of using a vision sensor. First, a method of using a laser sensor is a container while promoting unmanned construction of a yard crane having a lower height and a smaller scale than a container crane. The method of automatically recognizing and loading the presence of and the coordinate recognition algorithm for various objects on the crane has been suggested.

Second, the vision sensor is equipped with four cameras on the spreader to measure each corner of the container. This allows the container and the spreader to be docked correctly by imaging the holes at the corners of the container. will be.

However, the method using the above-mentioned laser sensor has a disadvantage in that the position error of the trolley itself cannot be considered because the sensor is attached to the trolley, and the method of using the vision sensor can be used only when the spreader is docked with the container. Since it is a video signal, the durability of the harsh environment of the port is low, and it is difficult to use it at night.

An object of the present invention is to solve such problems in the prior art, in the unloading operation for loading the container to the AGV in the container ship and the loading operation for lifting the container using a spreader in the AGV to load the container in the container ship This is for measuring the absolute position of the spreader which is essential for the automatic landing system. The position of the spreader is placed on the lower part of the container crane by using the laser displacement sensor mounted on the trolley on the land side. By accurately determining the absolute position of the spreader using the equipped laser scanner, the absolute position of the spreader can be detected for the automatic landing of the container, which can contribute to the unmanned port equipment because the on-shore trolley can automatically raise or lower the container on the AGV. To provide a method and an algorithm There is a purpose.

1A or 1B is a conventional automated terminal picture

Figure 2 is a state diagram showing the operating state of the present invention

Figure 3 is a perspective view of the whole of the present invention

Figure 4 is a graph showing the measurement range of the laser scanner of the present invention

5 is a graph showing spreader coordinates of data scanned using the laser scanner of the present invention.

6 is a graph showing the range of tolerances indicated by circles of the present invention.

7 is a graph showing a transformation relationship between two coordinate systems of the present invention.

8 is a block diagram showing an absolute position detection method of the present invention.

9 is a flowchart illustrating the algorithm of the present invention.

<Description of the symbols for the main parts of the drawings>

10: trolley 11: spreader

20: laser displacement sensor 30: AGV vehicle

40: laser scanner 50: vertical frame

50 ': connecting member 100: container crane

In the spreader position detection method for confirming the position of the spreader 11 and the container through the laser displacement sensor 20 mounted on the trolley 10 of the container crane 100, the container size information is input and the container is input to the buffer. Confirming the arrival position information of the land side spreader (S1); and confirming the position information of the land side spreader to load the container on the land side spreader (S2); and the laser displacement mounted on the trolley 10 After determining the correct position of the AGV vehicle 30 through the sensor 20, lowering the spreader 11 and measuring the displacement between the spreader 11 and the AGV vehicle 30 (S3); and a laser scanner Coordinate value of the spreader 11 through (40) ( , , , Measuring the step (S4); and the error range using the measured coordinates of the spreader 11 Checking step (S5); and the error range Re-measuring the spreader 11 coordinates by controlling the spreader 11 position and shake when it is not within the range (S6); and an error range When the container is satisfied, the container is loaded on the AGV vehicle 30 to raise the spreader 11 (S7). The absolute position of the spreader 11 is detected.

In the above, the displacement between the container and the AGV vehicle 30 in the step of determining the position of the AGV vehicle 30 is 0.2 m.

In the above, the spreader coordinate value through the laser scanner 40 , , , silver

to be.

In the above, the error range is confirmed by the coordinates of the spreader 11 measured by the laser scanner 40 Is

, When the error range is satisfied continuously for 2 seconds from the initial satisfaction point, the container is landed on the AGV vehicle 30.

In the above, the laser scanner 40 is mounted on the connecting member 50 'of the vertical frame 50 in a direction corresponding to the AGV vehicle 30.

In the above, the laser displacement sensor 20 mounted on the trolley 10 is vertically mounted corresponding to the laser scanner 40 mounted on the connecting member 50 'of the vertical frame 50.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention.

Figure 1a or 1b is a conventional automated terminal picture, Figure 2 is a state diagram showing the operating state of the present invention, Figure 3 is a perspective view showing the whole of the present invention, Figure 4 is a measurement range of the laser scanner of the present invention 5 is a graph showing spreader coordinates of data scanned using the laser scanner of the present invention, FIG. 6 is a graph showing a range of tolerances indicated by circles of the present invention, and FIG. 7 is a graph of the present invention. 8 is a block diagram illustrating a method for detecting an absolute position of the present invention, and FIG. 9 is a flowchart illustrating an algorithm of the present invention.

First, a technical configuration for implementing the present invention is a laser displacement sensor 20 mounted on the land side trolley 10 to set the absolute position of the spreader 11; The laser scanner 40 mounted on the connecting member 50 'of the land-side vertical frame 50 of the crane 100 to determine the relative position within the error range of the AGV vehicle 30 and the spreader 11; It is formed to provide a spreader 11 coordinate detection algorithm for determining the absolute position of the container landing on the AGV vehicle 30 by using the laser displacement sensor 20 and the laser scanner 40.

In the present invention, when the spreader loaded with the container is located within the set error range by measuring the coordinates of the spreader 11 using the relative value of the laser scanner 40 compared with the absolute value of the laser displacement sensor 20 fixed. To explain in more detail how to make an AGV vehicle land,

3 shows the position of the laser displacement sensor 20 and the laser scanner 40 in the container crane 100. The container crane 100 has almost no shaking of the container at the target position by the anti-shake system. The position of the container crane 100 and the AGV 30 is always constant with respect to the reference coordinate system, and the hoisted spreader 11 is always horizontal, that is, the top surface of the spreader 11 is always perpendicular to the direction of gravity. Assuming that the laser displacement sensor 20 is installed below the trolley 10 of the container crane 100 using the landing position of the container, which is a reference for landing on the AGV vehicle 30, as a reference coordinate system. The connecting member 50 'of the container crane vertical frame 50 corresponding to the displacement sensor 20 shows that the laser scanner 40 is mounted.

And the process of operating the spreader 11 using the laser displacement sensor 20, first measuring the displacement to the spreader 11 using the laser displacement sensor 20 installed in the trolley 10, At the time of unloading, when the distance between the container and the AGV vehicle 30 reaches 0.2M, the hoisting is stopped to measure the absolute position of the spreader 11. The interval of 0.2M is an amount obtained by experience, and the above interval value can be varied, and when the 0.2M interval is reached, the hoisting is stopped and the absolute position is measured through the laser scanner 40. This is an interval with respect to the Z axis on the reference coordinate system, so that the specified interval can be met.

FIG. 4 illustrates the measurement of the absolute position of the spreader 11 using the laser scanner 40. The trolley is mounted to a member 50 ′ formed at the center of the lower side of the vertical frame 50 of the container crane 100. The coordinate values of the two points of the spreader 11 in which the container is mounted in the vertical direction and correspond to the laser displacement sensor 20 mounted on the 10 are mounted to the AGV vehicle 30 from the trolley 10 to the AGV vehicle 30. It indicates that the measurement. At this time, the laser scanner 40 measures the coordinates of the sensor coordinate system of the laser displacement sensor 20, the laser scanner 40 continues to measure the spreader 11 at a sampling time of 10 Hz, and generated in the present invention If the algorithm is satisfied for two consecutive seconds from the initial satisfaction by the algorithm, it is recognized that the landing is sufficiently possible, and the container is landed on the AGV vehicle 30, and the spreader 11 releases the lock to move next. To move towards the container of the ship.

5 to 7 show the coordinate relationship of the algorithm of the present invention according to the laser sensor displacement 20 and the laser scanner 40 configured as described above, and the laser attached to the laser scanner in addition to the reference coordinate system, which is the reference for everything. There is a sensor coordinate system where the beam exits the origin and the plane being scanned is the xy plane, and there is an object coordinate system based on a point of the moving object to be measured. Here, the definition of each coordinate system will be examined, and the transformation relationship between the coordinate systems will be described.

First, the reference coordinate system r will be described to indicate the coordinate relationship. As a coordinate system that is an absolute reference for all coordinate transformations, all the values measured by the laser displacement sensor 40 and the results of the conversion algorithm are finally converted into the reference coordinate system. Is expressed. Here, in actual application, the ^r z axis of the reference coordinate system is set in the gravity direction, the rail direction of the container crane 100 is set in the ^r x axis, and the direction in which the boom extends in the ^r y axis. The upper left subscript r means the reference coordinate system.

The sensor coordinate system s is defined in the sensor itself and is a coordinate system that first expresses the value measured by the sensor. In the present invention, the point where the laser light source exits from the laser scanner 40 is taken as the origin of the coordinate system and used as the coordinate system for measuring the coordinates of an object using this light source.

The object coordinate system b is a coordinate system fixed to an arbitrary position of the measurement object, and the center of the container is the origin of the object coordinate system, and the upper surface is a plane perpendicular to the ^b z axis. When the container is shaken by hanging on the container crane 100, the object coordinate system also moves in space according to the movement.

Referring to the coordinate measurement using the laser scanner 40, first, in order to know the absolute coordinates of the spreader 11, the coordinate values in the sensor coordinate system must be found using the laser displacement sensor 20 and the laser scanner 40. . First, the displacement to the spreader 11 is measured using the laser displacement sensor 20 mounted on the trolley 10 as described above. The laser displacement sensor 20 can know the coordinate value parallel to the gravity direction by installing in parallel with the ^r z axis of the reference coordinate system. Since the measured displacement value is a prior operation of positioning the laser scanner 40 before use, the ^s z value for the sensor coordinate system is set to 0 when the 0.2 m interval is maintained. In other words, the ^s z value measured by the laser scanner 40 becomes zero. FIG. 4 shows measuring the spreader 11 using the laser scanner 40, and FIG. 5 shows a graph showing the displacement with respect to the measurement angle using the data collected by scanning. In FIGS. 4 and 5, the spreader 11 and the graph which represent the solid line represent the reference position which can be landed without error, and the dotted line shows the actual measuring position. Using this graph = , = Know the coordinates of. Here, the superscript S means a sensor coordinate system, and the subscripts 1 and 2 represent two coordinates of the spreader 11 in order. And, no superscript (') means the reference position, and the prime means the actual measurement position.

First, the reference position is measured by the laser scanner 40. Since the sensor coordinate system measured by the scanner is a cylindrical coordinate system, it is converted into a rectangular coordinate system using coordinate transformation.

, , ,

, , .

----- (One)

Therefore, the standard coordinates in the sensor coordinate system are as follows.

----- (2)

And as in the method of obtaining the reference position, the actual measurement position is as follows.

----- (3)

The laser scanner 40 is provided such that the ^r x axis of the reference coordinate system and the ^s x axis of the sensor coordinate system are parallel as shown in FIG. 3. In other words, only the x-axis rotation needs to be considered for the rotation relationship between two coordinate systems. Where the x-axis rotation If we translate dx, dy, dz about each axis, relationship between two coordinate systems is as follows.

----- (4)

here to be.

Using the above equation, the coordinates of the sensor coordinate system can be converted into the coordinates of the reference coordinate system. Therefore, the coordinate values of the spreader's standard coordinates and actual measurement coordinates can be expressed as follows.

----- (5)

----- (6)

In the above equation, the value of each element is known or determined by measurement. and , and The coordinate values of are all known. '

More specifically, when looking at the transformation relationship between the reference coordinate system and the sensor coordinate system, as shown in Figure 7, the coordinate value of the point measured by the sensor is a value for the sensor coordinate system, it should be converted to a value for the reference coordinate system . For this purpose, it is assumed that a reference coordinate system is first defined as a point outside the crane, and the crane is fixed. Then, a transformation matrix representing a transformation relationship between two coordinate systems can be obtained. The transformation matrix is a combination of the rotation matrix and the translation vector. Let's first look at the rotation matrix.

Using the z-y-x Euler angle to determine the azimuth relationship between two coordinate systems, the amount of rotation between the two axes is determined by the right hand rule. In general, three angles that are independent of each other are needed to determine the orientation between two coordinate systems. In addition, three angles that are independent of each other are required to determine the orientation between the reference coordinate systems. Then, the reference coordinate system is fixed, and the sensor coordinate system ^s x, ^s y, ^s z} with respect to the fixed reference coordinate system { ^r x, ^r y, ^r z} represents the angular displacement with respect to the z, y, and x axes. There are six unknowns as translational motions dx, dy, and dz for each axis. First, the rotation matrix is expressed as z-y-x Euler angle.

----- (7)

here to be.

The transformation matrix including the rotation matrix and the translation vectors (dx, dy, dz) is expressed in Equation (8) for the reference coordinate system and the sensor coordinate system.

----- (8)

So far, we have examined the general three-dimensional coordinate transformation. However, in the present invention, when the sensor is installed, the ^r x axis of the pseudo coordinate system and the ^s x axis of the sensor coordinate system will be installed in parallel so that the equation will be made simpler. This translates the rotation to ^r x or ^s You only need to consider. In addition, the translation vector determines the distance dx, dy, dz by measuring the distance from the reference coordinate system origin to the sensor coordinate system origin. In addition, as in Equation (8), rotation and translation amount can be known by using a transformation matrix between the sensor coordinate system and the object coordinate system.

As described above, Equation (3) is the measured value in the sensor coordinate system, and Equation (5) is the coordinate value converted into the reference coordinate system by Equation (4) or Equation (8), but in the present invention, all axes are rotated. Equation (8) is a general transformation determinant, and Equation (4) is a transformation matrix suitable for this situation. In other words, equation (3) is the coordinates of the spreader as seen from the sensor coordinate system, and equation (5) is the coordinates of the spreader (11) as seen from the reference coordinate system.

7 is a diagram for referring to the transformation of the coordinate system.

When raising and lowering the container on the AGV, constant coordinates must be maintained for landing without shaking. In practice, however, there are some tolerances when landing. In other words, the landing is possible when the spreader and the container, the container and the AGV is exactly within the tolerance range.

In FIG. 6, the standard coordinates and the actual measurement coordinates of the reference coordinate system are expressed together. Where radius around the world coordinate Suppose an employee is a landable tolerance. then and The distance between If smaller, landing is possible. In the same way and The same can be said for the following expressions.

---- (9)

In order to land, both conditions must be met. For example, in FIG. 6, the distance between the standard coordinate and the actual measurement coordinate for the corner point 1 is Greater than Distance from corner 2 Although smaller, landing is not possible in this situation. If the coordinate values of the two corner points of the spreader 11 are known, the remaining two corners have the fixed size of the spreader 11 so that they become dependent and the coordinate values on the reference coordinate system can be known. It can be determined whether or not landing.

Fig. 9 is a flowchart showing the algorithm of the present invention, in which a laser scanner shows two spreaders of a sensor coordinate system. , The way, the sensor coordinate system determined by the scanner cylindrical coordinate system because it is behind the illustrated as a rear reference position converted to a Cartesian coordinate system for the coordinate transformation to the standard coordinates in the sensor coordinate system, the laser scanner is ^r x axis of the reference coordinate system and the sensor coordinate system determined Assuming that the ^s x-axis are parallel to each other, the rotational relationship between the two coordinate systems only needs to consider the X-axis rotation. Therefore, the coordinates of the sensor coordinate system are calculated by using the X-axis rotation amount and the matrix obtained through the translational motion about each axis. Is obtained by converting the value to a reference position coordinate value relative to the reference coordinate system. , The coordinates and the actual position measured by the laser scanner , Use the coordinates to set the radius around the world coordinate Assuming the number of people as a landing error range, the error range is compared by comparing the difference between the reference position coordinate value and the actual position coordinate value. If satisfied, landing container on AGV vehicle If is not satisfied, it indicates that the process of measuring the two points of the sensor coordinate system with the laser scanner by controlling the spreader position and shaking again.

Let's apply the above algorithm to container crane 100. First, when unloading, the container loaded on the vessel is held by the spreader 11 and moved to the place where AGV is located. When the trolley 10 goes to the point coinciding with the AGV coordinate with respect to the reference coordinate system, it hoistes downward and finds the position of the spreader 11 to be measured by using the laser displacement sensor 20 so that the distance becomes 0.2m. After maintaining a constant interval, using the laser scanner 40 to measure the coordinate value for the sensor coordinate system. The laser scanner 40 continuously measures the spreader 11 at a sampling time of 10 Hz, and recognizes that the landing is sufficiently possible if the algorithm is satisfied continuously for 2 seconds from the first satisfying time by the above algorithm. Thus, the container can be placed on the AGV, and the spreader 11 releases the lock and moves to the ship by grabbing the next container.

As in the case of loading and unloading, when the AGV carrying the container approaches the crane, the spreader 11 comes down and checks the position using the laser displacement sensor 20 and the laser scanner 40, and whether the landing is possible through an algorithm. After confirming that the spreader 11 raises the container.

Thus, the present invention measures the displacement from the trolley to the spreader by using the laser displacement sensor and stops hoisting when the distance between the container and the AGV vehicle reaches 0.2m and uses the laser scanner to determine the position of the spreader horizontal movement. Fixed AGV knowing the coordinates with respect to the reference coordinate system and the absolute value of the spreader for the automatic landing of the container that can be landed to lower or lift the container if the position error of the xy plane in the reference coordinate system falls within the tolerance. It is characterized in that a method and an algorithm capable of detecting a position can be obtained.

Claims (6)

In the spreader position detection method for confirming the position of the spreader and the container through the laser displacement sensor 20 mounted on the trolley 10 of the container crane 100, the container size information is input, and the buffer arrived in the buffer land Confirming the positional information of the side spreader (S1); and confirming the positional information of the landside spreader and loading the container into the landside spreader (S2); and the laser displacement sensor 20 mounted on the trolley 10. After determining the exact position of the AGV vehicle 30 through the step of lowering the spreader 11, measuring the displacement between the spreader 11 and the AGV vehicle 30 (S3); and the laser scanner 40 The coordinates of the spreader 11 ( , , , Measuring the step (S4); and the error range using the measured coordinates of the spreader 11 Checking step (S5); and the error range Measuring the spreader 11 coordinates by controlling the spreader 11 position and shaking when the value is not within the corresponding range (S6); and an error range. Loading the container in the AGV vehicle 30 to raise the spreader 11 when satisfied (S7); and detecting the absolute position of the spreader 11 via the absolute spreader for automatic landing of the container. Position detection method and algorithm. The method and algorithm of detecting an absolute position of a spreader according to claim 1, wherein the displacement between the container and the AGV vehicle 30 in the step of determining the position of the AGV vehicle 30 is 0.2 m. . 2. Spreader coordinate measurements through the laser scanner (40) of claim 1 , , , silver Absolute position detection method and algorithm of the spreader for the automatic landing of the container. According to claim 1, Error range for measuring and confirming the coordinates of the spreader 11 through the laser scanner 40 Is , And an absolute position detection method of the spreader for automatic landing of the container, wherein the container is landed on the AGV vehicle 30 when the error range is satisfied continuously for 2 seconds from the initial satisfaction point. The spreader of claim 1, wherein the laser scanner 40 is mounted on the connecting member 50 ′ of the vertical frame 50 in a direction corresponding to the AGV vehicle 30. Absolute position detection method and algorithm. The laser displacement sensor 20 mounted on the trolley 10 is mounted vertically corresponding to the laser scanner 40 mounted on the connecting member 50 'of the vertical frame 50. Absolute position detection method and algorithm of spreader for automatic landing of container.