JP6058487B2 - Target for measuring the position of a hanging tool - Google Patents

Description

The present invention relates to a position measurement target to measure the position of the suspender of the crane to perform handling of the container.

  Conventionally, containers are handled at container terminals by quay cranes, portal cranes, and straddle carriers. When handling containers with these cranes, a method for measuring the position of a hanging tool (hereinafter referred to as a spreader) with a laser rangefinder has been proposed for the purpose of container stabilization and automation of handling (for example, patents). Reference 1).

  FIG. 8 shows an outline of a method for measuring the position of the spreader with a laser distance meter. The crane described in Patent Literature 1 includes a trolley 8 that travels along a girder 13 and the like, and a spreader 7 that is suspended from the trolley 8 via a wire rope 11. The crane also has a laser distance meter 9 installed on the trolley 8. This laser distance meter 9 emits lasers in a radial (fan shape) in order by rotating a mirror or the like, detects the reflected light, and determines the distance from the elapsed time t to the measurement point where the laser light is reflected. It has a configuration to calculate. Here, d and d 'indicate the interval between adjacent laser beams. H indicates the height H from the ground surface to the laser distance meter 9.

  Next, a method for measuring the position of the spreader 7 using the laser distance meter 9 will be described. First, the laser distance meter 9 sequentially irradiates the spreader 7 so that the locus of the laser beam forms a fan shape, and measures the elapsed time t until each reflected light is detected. The laser distance meter 9 acquires the emission angle αn of each laser beam and the distance Ln calculated from the elapsed time tn as polar coordinates (Ln, αn) of each measurement point Pn reflected by the laser beam. Thereafter, the position of the spreader 7 is estimated from the polar coordinates of each measurement point Pn. The laser light that has not collided with the spreader 7 is reflected by the ground surface 12 or the like and returns to the laser distance meter 9.

  Here, the emission angle αn indicates an angle formed by the laser light with respect to the perpendicular. The distance Ln indicates the distance from the lower end of the laser rangefinder 9 to the measurement point Pn where the laser beam is reflected. Further, Ls indicates a distance from the trolley 8 (or the laser distance meter 9) to the spreader 7 (hereinafter referred to as a reference height Ls).

The laser distance meter 9 has an angular resolution of, for example, about 0.125 to 1.000 degrees. That is, the laser distance meter 9 can irradiate the laser beam with the emission angle αn shifted by, for example, 0.125 degrees. Therefore, the laser beam interval d ′ can be obtained by the following equation.

  Here, the angle in the tangent indicates the difference between the emission angles αn of adjacent laser beams. For example, when the crane is a quay crane, if H = 100 m and the angle resolution is 0.125 degrees, which is the highest performance, the laser beam interval d ′ is about 218 mm, and the angle resolution is 1.0 degrees. Then, the distance d ′ is about 1750 mm. When the crane is a portal crane, if H = 30 m, the angular resolution is 0.125 degrees, which is the highest performance, the laser beam interval d ′ is about 65 mm, and the angular resolution is 1.0 degree. d ′ is about 523 mm.

  FIG. 9 shows a state in which measurement is performed by a conventional position measurement method. Specifically, an outline of how the spreader 7 is irradiated with laser light is shown. The laser beam collides with the spreader 7, is reflected at each measurement point P1 to P4, and returns to the laser distance meter 9 (not shown). The laser light that has not collided with the spreader 7 is reflected by the ground surface or the like (measurement point P5), and returns to the laser distance meter 9.

  FIG. 10 shows an example of measurement data obtained by the laser distance meter 9. The graph of FIG. 10 shows the polar coordinates (Ln, αn) of each measurement point Pn acquired by the laser distance meter 9 converted into orthogonal coordinates (Lnsin αn, Lncos αn). As can be seen from FIG. 10, the measurement points P <b> 1 to P <b> 4 on the spreader 7 have a substantially constant value (reference height Ls) in height (Lncos αn). Further, when the light is not reflected on the spreader 7, the height (Lncos αn) of the measurement point P5 is greatly different. Therefore, it can be seen that the side end portion (also referred to as an edge) of the spreader 7 is located between the measurement points P4 and P5 (see the broken line in FIG. 10).

  From the above, the laser distance meter 9 can estimate the position of the spreader 7. The crane realizes steadying control of the spreader 7 and automation of cargo handling by the trolley 8 based on the position information of the spreader 7.

  However, the method for measuring the position of the spreader 7 by the laser distance meter 9 has several problems. First, the measurement accuracy is low. This is because the laser beam reflected by the spreader 7 or the like has an interval d affected by the emission angle αn, and this interval d becomes a measurement error. That is, in this position measurement method, as indicated by a broken line in FIG. 10, it is impossible to know where the lateral end (edge) of the spreader 7 exists between the measurement points P4 and P5.

  Secondly, as the distance from the laser rangefinder 9 to the spreader 7 increases, the measurement accuracy decreases. This is because, as shown in FIG. 8, the distance d of the radial laser light increases to d 'according to the distance traveled. Generally, as the distance from the laser rangefinder 9 to the spreader 7 increases, the spreader 7 is more likely to shake, and control such as steadying is required. Therefore, when the laser distance meter 9 is most needed, the measurement accuracy is most degraded. Specifically, even when a laser rangefinder with the highest angular resolution is used for the quay crane, d 'is about 220 mm.

  Third, there is a problem that it is difficult to perform the steady rest control of the spreader 7 and the automatic cargo handling control with high accuracy and safety. This is because the above-mentioned measurement accuracy is insufficient to automate the handling of containers placed at intervals of about several tens of centimeters.

JP 2006-312521 A

The present invention has been made in view of the above problems, and an object of the present invention is to improve the measurement accuracy of measuring the position of a spreader in a position measuring target for measuring the position of a hanging tool (spreader), and in particular, a laser. An object of the present invention is to provide a position measurement target capable of maintaining measurement accuracy even when the spreader is separated from the distance meter.

In order to achieve the above object, a hanging position measuring target according to the present invention has a laser rangefinder installed on a trolley and a target installed on a hanging tool, and is suspended on the trolley. In the position measuring target of the position measuring device for measuring the position of the hanging tool, the target includes an inclined portion, and the inclined portion is a position coordinate of at least one measurement point of the inclined portion that reflects the laser beam. A predetermined shape from which the length from the upper end or the lower end of the inclined portion to the boundary portion can be derived , and the target is disposed through the boundary portion at the upper end or the lower end of the inclined portion. It has the part .

  With this configuration, the measurement accuracy of the position measuring device can be improved. This is because the position coordinates of the measurement point on the inclined part can be measured with a laser distance meter, the height of the measurement point on this inclined part can be obtained, and the position of the boundary part can be accurately calculated from this height. is there. In particular, even when the distance between the laser distance meter and the hanging tool (spreader) is long, the measurement accuracy of the position measuring device can be maintained.

It can be set as the structure in which the target has the inclined flat plate-shaped inclination part. Or it can be set as the structure which has the inclination part provided with the curved surface in which a target becomes convex or concave.

The target has a rectangular parallelepiped horizontal portion that is higher than the upper surface of the hanger, and two flat inclined portions that are inclined from the horizontal portion toward the upper surface of the hanger. And the target may have two boundary portions.

According to the hanging position measuring target according to the present invention, the measurement accuracy for measuring the position of the spreader can be improved, and the measurement accuracy can be maintained even when the spreader is separated from the laser distance meter. A position measurement target can be provided.

It is a diagram illustrating a schematic configuration of a position measuring device. It is the figure which showed the cross section of the target for position measurement of embodiment which concerns on this invention. Position is a diagram showing an example of data obtained by the location measurement device. It is the figure which showed the outline of the target for position measurement of different embodiment which concerns on this invention. It is the figure which showed the outline of the target for position measurement of different embodiment which concerns on this invention. It is the figure which showed the outline of the target for position measurement of different embodiment which concerns on this invention. It is the figure which showed the cross section of the target for position measurement of different embodiment which concerns on this invention. It is the figure which showed the outline of the structure of the conventional position measuring method. It is the figure which showed the mode at the time of the measurement by the conventional position measuring method. It is the figure which showed the example of the data acquired by the conventional position measuring method.

Hereinafter, a position measuring target for a hanging tool according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a schematic configuration of a position measuring device 1. The position measuring device 1 has a laser distance meter 9 installed on a trolley 8 and at least one target 2 of the present invention installed on a hanging tool (hereinafter referred to as a spreader) 7. Further, the position measuring device 1 has an arithmetic device 3 connected to the laser distance meter 9 by a signal line (not shown). The laser light of the laser distance meter 9 is irradiated so as to spread in the x-axis direction, for example. Further, it is desirable that the target 2 be accurately installed at a predetermined position of the spreader 7.

  In FIG. 2, the outline of the cross section of the target 2 is shown. The target 2 fixed to the spreader 7 has a flat horizontal portion 21 and an inclined portion 22 having, for example, a prismatic cross section. The inclined portion 22 is formed to have a predetermined angle θ with respect to the horizontal portion 21. Here, reference numeral 23 denotes a boundary portion 23 (also referred to as an edge) at the lower end of the inclined portion 22. The horizontal portion 21 is disposed via a boundary portion 23 at the lower end portion of the inclined portion 22.

  Here, the length D1 of the horizontal portion 21 and the length D2 of the inclined portion 22 in the x-axis direction are determined so that at least one of the laser beams can be reflected in an area where the position measurement of the spreader 7 is necessary. (D1> d, D2> d). According to the calculation formula shown in Equation 1 above, for example, when a laser rangefinder with an angular resolution of 0.125 degrees is used with a quay crane with H = 100 m, the laser beam interval d ′ is about 220 mm. Therefore, it is desirable that the lengths D1 and D2 be longer than 220 mm. Further, for example, the length of the target 2 in the y-axis direction (the front and back direction in FIG. 2) can be about 800 to 1000 mm, and the height in the z-axis direction can be about 100 to 150 mm. Note that the size of the target 2 is not limited to the above, and it is sufficient that the laser beam is reflected at least by the inclined portion 22 when the position of the spreader 7 is measured.

  Next, a method for measuring the position of the spreader 7 by the position measuring apparatus 1 will be described. First, as shown in FIG. 2, a laser distance meter 9 (not shown) irradiates the target 2 with laser light. This laser beam is reflected at each of the measurement points P1 to P5 (hereinafter collectively referred to as measurement point Pn). The laser distance meter 9 acquires the position coordinates (polar coordinates) of each measurement point Pn from the distance Ln to the measurement point Pn on the target 2 or the spreader 7 and the laser beam emission angle αn (position coordinate acquisition step). The position coordinates of each measurement point Pn are sent to the computing device 3 as needed.

  FIG. 3 shows the polar coordinates (Ln, αn) of each measurement point Pn acquired by the laser distance meter 9 converted into orthogonal coordinates (Lnsin αn, Lncos αn). P1 in FIG. 3 indicates position coordinates of the measurement point P1 on the spreader 7, and P2 and P3 indicate position coordinates of the measurement points P2 and P3 on the horizontal portion 21 of the target 2. The measurement point P4 indicates the coordinates of the portion of the inclined portion 22 that reflects the laser light. Furthermore, the measurement point P5 indicates the coordinates of the portion where the laser beam is reflected on the ground surface.

  Here, Ls represents a reference height that is the same as the height of the upper surface of the spreader 7 or the height of the horizontal portion 21 of the target 2. The reference height Ls can be obtained from an encoder or the like that measures the wire rope feed amount of the spreader 7. The reference height Ls obtained as described above is sent to the arithmetic device 3 (reference height acquisition step).

  Next, calculation processing by the calculation device 3 will be described. First, the arithmetic device 3 compares the position coordinates of the plurality of measurement points Pn obtained by the laser distance meter 9 with the reference height Ls obtained by an encoder or the like (comparison step). From this comparison, it can be estimated that the measurement points P <b> 1 to P <b> 3 located at a distance relatively close to the reference height Ls are on the horizontal portion 21 or the spreader 7. In addition, it can be estimated that the measurement point P4 whose distance has changed greatly first from the measurement point on the horizontal portion 21 is on the inclined portion 22. That is, it can be estimated that a boundary portion 23 (see FIG. 2) between the horizontal portion 21 and the inclined portion 22 exists between the measurement points P3 and P4 (point narrowing step).

  The reference height Ls can be acquired by a method that does not use an encoder or the like. For example, the provisional reference height Ls ′ is arbitrarily determined, and the comparison step and the point narrowing step are executed on the provisional reference height Ls ′. In the process, the height (Lncos αn) of the measurement point estimated to be on the horizontal portion 21 or the spreader 7 is used as the reference height Ls. In this case, the average value of P1 to P3 can be set as the reference height Ls, or the height of only the horizontal portion 21 can be extracted and set as the reference height Ls.

  With this configuration, the measurement accuracy of the position measuring device 1 can be improved. This is because the height of the horizontal portion 21 or the spreader 7 measured by the laser distance meter 9 with a small measurement error is used as the reference height Ls. Note that when an encoder or the like is used, a measurement error slightly occurs due to the influence of the wire rope 11 or the like. On the other hand, the measurement error of the laser distance meter 9 is extremely small.

Next, as shown in FIG. 2, the arithmetic device 3, for example, from the reference height Ls determined as the height of the upper surface of the horizontal portion 21 and the position coordinates of at least one measurement point P4 on the inclined portion 22, The height δ of the measurement point P4 is calculated (inclined portion height δ calculating step). The height δ calculated here is substituted into the shape function of the inclined portion 22 of the target 2 input in advance to the arithmetic device 3. Specifically, as shown in FIG. 2, when the inclined portion 22 of the target 2 is inclined at an angle θ with respect to the horizontal portion 21, the shape function of the inclined portion 22 can be expressed by the following expression.

  From the above formula, the distance x in the horizontal direction (x-axis direction) from P4 to the boundary portion (edge) 23 is obtained (boundary portion calculation step). As described above, the position coordinates of the boundary portion 23 obtained with high accuracy can be obtained, and the position of the spreader 7 can be accurately measured from the position coordinates of the boundary portion 23.

With the above configuration, the spreader position measuring target 2 of the present invention can obtain the following effects. First, the measurement accuracy for measuring the position can be improved. This is because the position coordinate of the measurement point Pn on the inclined portion 22 is measured by the laser distance meter 9, the height δ of the measurement point Pn of the inclined portion with respect to the reference height Ls is obtained, and the position of the edge 23 is determined from this height δ. This is because can be calculated accurately.

  At this time, the position of the edge 23 can be determined with much higher accuracy than the length of the laser beam interval d (for example, about 100 to 300 mm), which is a conventional measurement error. Specifically, the error in measuring the position of the edge 23 is affected by a measurement error (about ± several mm) by the laser distance meter 9 and a dimensional error in fixing the target 2 to the spreader 7. is there.

  Secondly, the position measuring device 1 can achieve high measurement accuracy even when the position of the spreader 7 is far away from the laser distance meter 9. This is because the measurement accuracy of the position measuring apparatus 1 has a configuration that is not affected by the interval d of the laser light.

  Thirdly, by improving the measurement accuracy for measuring the position of the spreader 7, the direction and acceleration of the spread when the spreader 7 is swung can be measured with high accuracy. This is because the change in the position of the spreader 7 can be measured with almost no error.

4 shows a schematic of a position measurement target 2A of different embodiments according to the present invention. The target 2 </ b> A includes a rectangular parallelepiped horizontal portion 21 </ b> A that is higher than the upper surface of the spreader 7, and a flat plate-shaped inclined portion 22 </ b> A that is inclined downward from the horizontal portion 21 </ b> A toward the upper surface of the spreader 7. Reference numeral 23 denotes an edge 23 whose position is measured by the arithmetic device 3.

  At this time, the reference height Ls can be set on the upper surface of the horizontal portion 21A. The reference height Ls may be obtained by adding the height of the horizontal portion 21A to the height of the upper surface of the spreader 7 obtained by an encoder or the like, and is estimated from the position coordinates of the measurement point Pn on the upper surface of the horizontal portion 21A. May be. Further, when the inclined portion 22A has an angle θ made with respect to the horizontal plane, the shape function of the target 2A can be expressed by the same equation as the above-described equation 2.

5 shows a schematic of a position measurement target 2B of different embodiments according to the present invention. The target 2B has a flat horizontal portion 21B and an inclined portion 22B having a curved surface that protrudes from the horizontal portion 21B. The inclined portion 22B has, for example, a shape obtained by dividing a cylinder into four equal parts in the axial direction. When the inclined portion 22B has a fan shape with a radius r and a central angle of 90 degrees, the shape function can be expressed by the following equation.

  Here, x represents the distance x in the horizontal direction (x-axis direction) from the measurement point on the inclined portion 22B to the edge 23.

Similarly, Figure 6 shows a schematic of a position measurement target 2C of different embodiments according to the present invention. The target 2C has a flat horizontal portion 21C and an inclined portion 22C having a curved surface that is concave from the horizontal portion 21C. When the inclined portion 22C has a shape formed by hollowing out a fan shape having a radius r and a central angle of 90 degrees from a rectangular parallelepiped, the shape function can be expressed by the following equation.

  Here, x represents the distance x in the horizontal direction (x-axis direction) from the measurement point on the inclined portion 22C to the edge 23.

  As described above, the target inclined portion can determine the distance x to the edge 23 from the height δ of the measurement point on the inclined portion with respect to the reference height Ls and the predetermined shape function. Therefore, the inclined portion only needs to have a shape that allows the distance x to be uniquely determined with respect to the height δ. Specifically, even a discontinuous shape in which the angle of the inclined portion changes in the middle is sufficient as long as one distance x can be derived with respect to the height δ. The reference height Ls may be set to any height between the upper end and the lower end of the inclined portion, but is preferably set to the height of the upper end or the lower end of the inclined portion. This is because this configuration can simplify the calculation for obtaining the position of the boundary portion.

The targets 2, 2 </ b> A, 2 </ b> B, and 2 </ b> C are illustrated as having a longitudinal direction in the y-axis direction, but the position measurement target 2 of the present invention is not limited to this configuration. The target 2 may be installed on the spreader 7 so as to have a longitudinal direction in the x-axis direction. For example, the target 2 may be installed so as to have a longitudinal direction in a direction inclined by 45 degrees with respect to the x-axis direction.

  The number of targets 2 to be installed may be at least one on the spreader 7, but can be changed as appropriate according to necessary information such as the position and orientation of the spreader 7. That is, the number of targets 2 is increased, and in addition to the distance L from the laser rangefinder 9 to the spreader 7, the rotation of the spreader 7 in the turning direction (rotation about the vertical axis z) and the inclination with respect to the horizontal plane (x-axis) And rotation about the y-axis).

Figure 7 shows the position schematically the measurement target 2D of different embodiments according to the present invention. The target 2D includes a rectangular parallelepiped horizontal portion 21D that is positioned higher than the upper surface of the spreader 7, and two flat inclined portions 22D that are inclined downward from the horizontal portion 21D toward the upper surface of the spreader 7. Yes. That is, the target 2D is configured to have two edges 23.

  At this time, the reference height Ls can be the height of the upper surface of the horizontal portion 21D. Moreover, the measurement point on each inclined part 22D can be specified from the coordinates of the measurement point on the upper surface of the horizontal part 21D.

  With this configuration, it is possible to prevent the occurrence of an error when measuring the position of the spreader 7. This is because, for example, even when the reflected light of the laser beam is not sufficiently obtained due to water droplets such as rain attached to one inclined portion 22D, the spreader 7 is reflected by the reflected light from the other inclined portion 22D. This is because the position of can be measured.

  In addition, the position measuring device employing the target 2D can measure the inclination even when the spreader 7 rotates around the axis z and has an inclination. This is because the inclination of the spreader 7 can be calculated from the comparison between the predetermined distance between the two edges 23 and the apparent distance between the two edges 23 measured by the position measuring device. It is.

  The laser distance meter 9 may be a two-dimensional laser distance meter in which the laser beam trajectory forms a fan shape, or a three-dimensional laser distance meter in which the laser beam trajectory forms a conical shape. In accordance with this laser distance meter, the target can be formed into a truncated cone shape, for example, and can be expanded to three dimensions. With this configuration, it is possible to measure details such as rotation of the spreader without increasing the number of laser rangefinders and targets.

  Further, the horizontal portion 21 of the target 2 may be configured to use the top surface of the spreader 7 or the like. That is, the target 2 having only the inclined portion 22 may be installed on the flat top surface of the spreader 7. In this case, the boundary portion (edge) 23 is the upper end or the lower end of the inclined portion 22. With this configuration, the manufacturing cost of the target can be suppressed. At this time, the height of the top surface of the spreader 7 can be extracted and used as the reference height Ls.

DESCRIPTION OF SYMBOLS 1 Position measuring device 2, 2A, 2B, 2C, 2D Target 3 Computation device 7 Spreader 8 Trolley 9 Laser distance meter 21, 21A, 21B, 21C, 21D Horizontal part 22, 22A, 22B, 22C, 22D Inclination part 23 Boundary part (Edge)
Ln Distance from the laser distance meter to the measurement point Ls Reference height Pn, P, P1, P2, P3, P4 Measurement point δ Height of the inclined portion (measurement point) d (Laser beam) interval

Claims (4)

In a position measuring target of a position measuring device that has a laser distance meter installed on a trolley and a target installed on a hanging tool and measures the position of the hanging tool suspended on the trolley,
The target has an inclined portion;
The inclined portion has a predetermined shape capable of deriving the length from the position coordinates of at least one measurement point of the inclined portion that reflects the laser light to the boundary portion of the upper end or the lower end of the inclined portion ,
The target has a horizontal portion arranged via the boundary portion at the upper end or the lower end of the inclined portion . The target according to claim 1 , wherein the target has the inclined flat plate-shaped inclined portion. The target according to claim 1 , wherein the target includes the inclined portion having a curved surface that is convex or concave.   The target has a rectangular parallelepiped horizontal portion that is higher than the upper surface of the hanging tool, and two flat inclined portions that are inclined from the horizontal portion toward the upper surface of the hanging tool. The target according to claim 1, wherein the target has two boundary portions.