JP2005263331A - Vehicle position measuring method of harbor crane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide vehicle position measuring device and method, correcting an error due to shifting in direction of a sensor caused by vibration, rocking, or thermal deformation in actual work at the time of measurement. <P>SOLUTION: In this vehicle position measuring method of a harbor crane, the position of the vehicle 7 is measured on the basis of distance data input from a laser range finder 1 and the scan angle input from an angle measuring part 4 using the laser range finder 1, the scanner 3 scanning the laser range finder 1 and the angle measuring part 4 for measuring the scan angle of the scanner 3. The inclination of the ground is measured beforehand, and a difference between the inclination of the ground measured in the actual work and the inclination measured beforehand is obtained to correct a measurement error on the basis of the difference. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a vehicle position measurement method in a container loading / unloading operation on a transportation vehicle by a harbor crane.

In order to make the port crane work more efficiently by accurately positioning the port crane for container handling on a transport vehicle such as a truck or by accurately positioning the truck etc. at a predetermined position under the crane. An apparatus for measuring the position of a vehicle by attaching a laser range finder with a scanner to is known (for example, Patent Document 1). FIG. 4 is a conceptual diagram of the apparatus disclosed in Patent Document 1. In this apparatus, a laser sensor 5 comprising a mirror 3 that can be rotated so as to scan a laser beam 2 output from a laser rangefinder 1 and an angle detection device 4 that detects the rotation angle thereof is installed on a crane 6. It is. The laser sensor 5 performs measurement on the vehicle 7 below, obtains a rear position 8 thereof, and guides the trolley 9 directly above the vehicle 7. FIG. 5 is a diagram showing an operation flow of this apparatus. As shown in FIG. 5, when scanning is started (step 1), the value of the laser distance meter is read (step 2), and the scan angle at that time is detected (step 3). These measurement data are converted into an XY coordinate system (step 4). These operations are repeated, and when the measurement is completed up to a predetermined measurement range, the scan is terminated (step 6). The XY coordinate converted measurement data group is differentiated in the X direction (step 7), and the edge position of the vehicle rear position 8 is detected and output (step 8).
In fields other than harbor cranes, there is a method of increasing the measurement accuracy by installing a plurality of reference targets and measuring the reference target together with the measurement target. (For example, patent document 2). In this method, a method of measuring the position with high accuracy by measuring the distance to three or more reference targets whose positions are known separately from the measurement target and the projection angle at that time is also taken. It was.
JP 2002-255476 A JP-A-8-54234

In conventional port crane vehicle position measuring devices, the vehicle position is determined by the distance and the scan angle, so the vibration of the laser sensor caused by the movement of the trolley during actual work, the wind of the laser sensor, the thermal deformation, etc. There is a problem that an error occurs. In particular, the influence of the angle error in the same direction as the scan direction on the measurement accuracy is significant, and there is a problem that the transport vehicle cannot be guided to an appropriate cargo handling work position. Also, during actual work, installing a reference target near the transport vehicle becomes an obstacle to cargo handling work, which is also a problem in terms of safety.
The present invention has been made in view of such problems, and can correct errors caused by deviations in the direction of the sensor caused by vibration or shaking during actual work or thermal deformation at the time of measurement. It is an object of the present invention to provide an apparatus and a method capable of performing highly accurate vehicle position measurement without installing a reference target that can be an obstacle in cargo handling work.

In order to solve the above problem, the present invention includes a laser distance meter, a scanner that scans the laser distance meter, and an angle measurement unit that measures a scan angle of the scanner, and a distance input from the laser distance meter. In the vehicle position measuring device of the harbor crane that measures the position of the vehicle based on the data and the scan angle input from the angle measuring unit,
Means for measuring and storing the inclination of the ground in advance, means for obtaining a difference between the inclination of the ground measured in actual work and the inclination measured in advance, and means for correcting a measurement error based on the difference Is provided.

  According to the present invention, it is possible to accurately measure a vehicle position by correcting an error caused by vibration or shaking during actual work or thermal deformation during measurement.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram of a vehicle position measuring apparatus showing an embodiment of the present invention, and FIG. 2 is a flowchart showing a processing procedure by the vehicle position measuring apparatus. The laser sensor 5 has the same configuration as that described in the prior art example, and includes a laser distance meter 1, a rotatable mirror 3, and an angle detection device 4 for measuring the mirror angle. The laser beam 2 emitted from the laser distance meter 1 is reflected by the mirror 3 and irradiated onto the measurement object. At this time, the value of the laser distance meter 1 is read and at the same time the angle detection device 4 detects the angle of the mirror 3. The irradiation angle 12 of the irradiated laser beam 2 is measured. The value of the laser distance meter at this time is l, the distance from the laser distance meter 1 to the mirror 3 is d, and the laser irradiation angle is θ. When this is converted into XY coordinates with the mirror 3 as a reference and the X axis as the vehicle traveling direction and the Y axis as the downward direction from the mirror 3, the coordinates are:

       (x, y) = ((l-d) sinθ, (l-d) cosθ) (Equation 1)

It becomes. Similarly, measurement is repeated while rotating the mirror 3 and changing the irradiation angle 12 of the laser beam. FIG. 3 is a diagram illustrating an example of measurement data converted into the XY coordinate system. In this example, a portion 13 where the ground 11 is measured and a portion 14 where the vehicle 7 is measured are observed. For easy understanding, these measurement data are represented by lines in FIG. 3, but are actually point sequences. In general, the vehicle lane that handles harbor cranes can be considered to be almost horizontal. However, even when there is no vibration or shaking, the ground portion may be displayed in an inclined straight line as shown in FIG. Among the measurement data converted into these XY coordinate systems, the measurement data is divided from the distance to the laser distance meter 3, the difference from the measurement value in the vicinity, and the like, and the data 13 obtained by measuring the ground portion is cut out. _Let (x _n , y _n ) be the coordinates of individual data obtained by measuring the cut ground portion. Since the linear equation of the ground is expressed as y = ax + b,

It becomes. When the left side of Equation 2 is XC and the right side is Y and C is obtained by the least square method,

Can calculate the linear equation of the ground, and the ground inclination φ can be obtained. The inclination φ of the ground portion is obtained in advance without any vibration or shaking, and stored in the memory. Similarly, during actual work, the value of the laser distance meter 1 and the laser irradiation angle 12 are sequentially measured while rotating the mirror 3 and converted into the XY coordinate system. If there are vibrations or vibrations caused by the movement of the trolley 9 or errors due to thermal deformation, the data obtained by measuring the ground part at this time is the data of the ground part measured in advance without vibrations or shaking. Indicates a value different from the data. If the scanning cycle of the laser sensor 5 is sufficiently small with respect to the crane vibration or shaking cycle, the measurement data 13 of the ground portion is also observed as a substantially straight line. The inclination of the ground portion at this time is calculated, and a difference Δφ with respect to the inclination of the ground portion stored in advance in the memory is obtained. This value Δφ represents an angular error 10 that is a component that is caused by vibration, shaking, thermal deformation, or the like and greatly affects the measurement accuracy. Therefore, conversion formula with correction amount added

       (x, y) = ((l-d) sin (θ-Δφ), (l-d) cos (θ-Δφ)) (Formula 4)

By converting the measurement data into the XY coordinate system again and taking the X-direction differentiation from the converted measurement data, the position 8 of the rear edge portion of the vehicle can be measured with high accuracy.

In the present embodiment, the method of measuring the rear edge portion of the vehicle after performing the reconversion of all the measurement data by the conversion formula including the correction amount has been described, but the rear edge portion of the vehicle is determined by the data before the reconversion. It is also possible to reduce the amount of calculation by measuring first and converting with a conversion formula in which a correction amount is added to only the distance data and irradiation angle of the edge portion.
In addition, instead of using X-direction differentiation as a method for measuring the rear edge portion of the vehicle, a vehicle is provided by cutting out only the vehicle measurement data by providing a measurement window near the vehicle height with respect to the data after XY conversion. It is also possible to measure the rear edge portion.

  As described above, according to the present invention, since the position of the transport vehicle can be measured with high accuracy even during actual work, the present invention can be applied to improve work efficiency of harbor crane handling work.

It is a conceptual diagram of the vehicle position measuring device which shows the Example of this invention. It is a flowchart of the vehicle position measuring method which shows the Example of this invention. It is a figure which shows the measurement data by this invention. It is a conceptual diagram of the vehicle position measuring device which shows the example of a prior art. It is a flowchart of the vehicle position measuring method which shows the example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser distance meter, 2 Laser light, 3 Mirror, 4 Angle detection apparatus, 5 Laser sensor, 6 Crane, 7 Vehicle, 8 Vehicle rear position, 9 Trolley, 10 Angle error, 11 Ground, 12 Laser irradiation angle, 13 Ground Measurement data, 14 vehicle section measurement data, 15 Ground tilt

Claims (2)

A laser rangefinder, a scanner that scans the laser rangefinder, and an angle measurement unit that measures a scan angle of the scanner, and distance data that is input from the laser rangefinder and scan that is input from the angle measurement unit In the vehicle position measuring device of the harbor crane that measures the position of the vehicle based on the angle,
Means for measuring and storing the inclination of the ground in advance, means for obtaining a difference between the inclination of the ground measured in actual work and the inclination measured in advance, and means for correcting a measurement error based on the difference A vehicle position device for a harbor crane, comprising: Using a laser distance meter, a scanner that scans the laser distance meter, and an angle measurement unit that measures a scan angle of the scanner, distance data input from the laser distance meter and an angle measurement unit In the vehicle position measurement method of the harbor crane that measures the position of the vehicle based on the scan angle,
A harbor characterized by measuring the inclination of the ground in advance, obtaining a difference between the inclination of the ground measured in actual work and the inclination measured in advance, and correcting a measurement error based on the difference Crane vehicle position measurement method.

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