CN113326803B - Crane hook/hanging object swing angle detection method and system - Google Patents
Crane hook/hanging object swing angle detection method and system Download PDFInfo
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Abstract
The invention discloses a method and a system for detecting a swing angle of a crane hook/a suspended object, wherein the method comprises the steps of acquiring a real-time marker image; preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates and the radius of the N light sources on the marker; respectively inputting the radius into a preset fitting curve function of the initial calibration radius, the initial calibration circle center coordinate and the rope length to obtain the initial calibration circle center coordinate of the current rope length and the common circle; and calculating the actual offset distance of the marker and calculating by combining the length of the rope to obtain a value of the swing angle. The method of three-point co-circle and multiple averaging realizes automatic detection of the rope length and rapid detection of the swing angle, and has the advantages of good stability, high precision and high speed; the method is simple to implement, and the problem that the swing angle of the crane hook/hanging object is difficult to detect quickly on line is solved; the method provides technical support for further realizing the closed-loop anti-swing control technology of the crane, and has a good application prospect in the intelligent development process of the crane.
Description
Technical Field
The invention relates to the technical field of heavy machine lifting hook/lifting object state monitoring, in particular to a method and a system for detecting a swing angle of a crane lifting hook/lifting object.
Background
The crane generally comprises a bridge, a cart moving device, a trolley moving device, a lifting device, a control room and the like, wherein the bridge longitudinally moves along rails on two sides, the empty space below the bridge can be fully utilized to hoist goods, and the crane is convenient and labor-saving and widely applied to places such as workshops, harbors and docks, warehouses, high-rise building construction sites and the like.
The crane can generate very large operation swing in the working process, so that the production efficiency is seriously reduced, and the sling of the crane can be seriously damaged; the metal structure is damaged, such as fracture, looseness and the like; and the danger of gnawing the rail is also buried for the later use of the crane, so that economic loss is caused and the safety of workers is harmed.
In the past, almost all the operation swing of the crane is eliminated by using the experience of an operator, and the mode has poor precision, low efficiency and large operation difficulty and can not meet the requirements of modern industry for a long time. The existing anti-swing control mainly comprises open-loop control, closed-loop control and a mode of combining open-loop control and closed-loop control. Open loop control is easy to implement, but not precise enough; the closed-loop system has good accuracy, but the position of the trolley and the swing angle of the hoisted object need to be measured at any time as feedback quantity of the controller, wherein the position of the trolley can be obtained through a crane main controller PLC, and the key for realizing closed-loop anti-swing control is how to measure and obtain the swing angle of the hoisted object.
In the related research of the existing crane hook/hanging object swing angle detection, there are some patent documents about a crane swing angle detection device and a method, application publication numbers CN111646357A and CN111348544A are on a coupling defined between a pulley block fixed pulley and the suspension arm, a detector is arranged to detect a hook swing angle of a pulley block force action line deviating from a plumb line angle, and the method is complicated and cannot be widely applied; application publication numbers CN111422739A and CN110775818A adopt a machine vision technology to carry out swing angle detection, but do not consider conditions such as ambient light and the like, and the swing angle detection method is not clear and the precision is unknown; due to the defects, the swing angle detection devices and the swing angle detection methods are not popularized and applied in a large scale in practical production.
Disclosure of Invention
The invention provides a method and a system for detecting a swing angle of a crane hook/a suspended object, which aim to solve the problem of low online detection precision of the existing crane hook/the suspended object swing angle.
In a first aspect, a method for detecting a swing angle of a crane hook/hoisted object is provided, which includes:
acquiring a real-time marker image, wherein the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circle with the radius of R on the upper surface of the marker, and N is more than or equal to 3; the real-time marker image is acquired by an image acquisition device arranged above the marker;
preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ，y i ) And radius thereof
Radius will be
Respectively inputting the preset fitting curve functions of the initial calibration radius, the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ，y 0 )；
The value of the swing angle θ is calculated by:
wherein D is p Indicating the actual offset distance of the marker,
k represents a magnification or reduction coefficient, device for selecting or keeping>
According to the scheme, the plurality of light sources are arranged on the marker, the center and the radius of the common circle are obtained through the principle of three-point common circle, then the radius of the common circle is input into a preset fitting curve function of an initial calibration radius, initial calibration center coordinates and rope length, the current rope length l and the initial calibration center coordinates of the common circle are obtained, and then the swing angle is obtained based on the current rope length l and the offset distance of the center of the common circle. The circle center coordinate is obtained by a method of solving the circle center through three points in a circle, and compared with a mode of determining the coordinate by a single light source, the method reduces the error and improves the calculation precision of the swing angle.
Further, the preprocessing process comprises:
carrying out noise reduction processing on the real-time marker image;
processing the denoised real-time marker image by adopting an edge detection algorithm to obtain a light source light spot profile corresponding to each light source;
processing the outline of each light source light spot by adopting a connected domain function to obtain the circle center coordinate d of each light source light spot i (x i ，y i )(i＝1，2，...，N)；
And calculating to obtain a real-time circle center coordinate of the co-circle based on a three-point co-circle method, and further obtaining the radius of the co-circle based on the real-time circle center coordinate of the co-circle.
Further, the method based on three-point co-circle calculates to obtain co-circle real-time circle center coordinates, and further obtains the radius of the co-circle based on the co-circle real-time circle center coordinates, which specifically includes:
based on the method of three-point co-circle, the centers of the three-point co-circle of the N light sources are co-circle
Get->
Circle center coordinate D j The mean value of the sum of the two is used to obtain the coordinates of the real-time circle center of the common circle>
The radius of the common circle is calculated by the following formula:
obtained by randomly selecting three light sources and utilizing the three-point co-circle principle
And finally, the final real-time circle center coordinate is obtained by averaging the circle center coordinates, so that the error is reduced, and the detection precision is improved.
Further, the noise reduction processing includes: selecting a cross-shaped structural element, performing opening operation of morphological processing on the real-time marker image, and removing a fine area with higher brightness in a light source spot of the real-time marker image;
when a plurality of circle centers corresponding to the light source light spot profiles are processed by adopting the connected domain function, one circle center is randomly reserved, and other coordinates are removed.
Further, the preset fitting curve function of the initial calibration radius, the initial calibration circle center coordinate and the rope length is obtained by the following method:
collecting marker images with different rope lengths and in a static state;
respectively preprocessing the marker images under different rope lengths to respectively obtain the co-circle initial calibration circle center coordinates D under different rope lengths 0 (x 0 ，y 0 ) And initial calibration radius
/>
Initial radius calibration for a common circle
Circle center coordinate D initially calibrated with a common circle 0 (x 0 ，y 0 ) And fitting a curve with the rope length L to obtain a fitting curve function:
further, when marker images in different rope lengths and static states are acquired, n frames of marker images are acquired under different rope lengths respectively;
circle center coordinate D of initial calibration of common circle 0 (x 0 ，y 0 ) And initial calibration radius
By averaging, we obtain:
wherein,
represents the co-circle center coordinates corresponding to different frame marker images under the same rope length, and then is matched with the standard rope length>
And the corresponding co-circle radius of different frame marker images under the same rope length is shown.
Method for determining initial calibration circle center coordinate D by multiple detection averaging 0 (x 0 ，y 0 ) And initial calibration radius
Improves the initial calibration circle center coordinate D 0 (x 0 ，y 0 ) And an initial calibration radius>
The accuracy of (2).
Furthermore, the included angle between adjacent light sources in the N light sources on the marker is 30-100 degrees, the light sources are invisible light band lamps, and the front end of the image acquisition device is provided with a light filter corresponding to the light source band. The included angle between the adjacent light sources is set to be 30-100 degrees, so that the precision of solving the circle center of the common circle based on the three-point common circle principle can be improved. The combination of the light source and the optical filter for collecting invisible light wave band eliminates the influence of ambient light and has strong anti-interference capability.
In a second aspect, there is provided a crane hook/hoisted object swing angle detection system comprising: a marker, an angle detector; the angle detector comprises an image acquisition device and a controller;
the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circumference with the radius of R on the upper surface of the marker, and N is more than or equal to 3;
the image acquisition device is used for acquiring a real-time marker image and sending the real-time marker image to the controller, the image acquisition device is vertically and downwards installed on the crane trolley, and the marker is positioned in the center of the visual field of the image acquisition device when the lifting hook is static;
the controller comprises an image preprocessing module, a rope length and circle center detection module and a swing angle calculation module;
the image preprocessing module is used for preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ，y i ) And radius thereof
The rope length and circle center detection module is used for detecting the radius
Respectively inputting the preset fitting curve functions of the initial calibration radius, the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ，y 0 )；
The swing angle calculation module is used for calculating a value of a swing angle theta through the following formula:
wherein D is p Indicating the actual offset distance of the marker,
k represents a magnification or reduction coefficient, device for selecting or keeping>
/>
Furthermore, the included angle between adjacent light sources in the N light sources on the marker is 30-100 degrees, the light sources are invisible light band lamps, and the front end of the image acquisition device is provided with a light filter corresponding to the light source band.
Furthermore, level gauges are arranged on the marker and the image acquisition device.
Advantageous effects
The invention provides a method and a system for detecting the swing angle of a crane hook/a suspended object, which have the following advantages:
(1) The method of three-point co-circle and multiple average value calculation realizes automatic detection of the rope length and rapid detection of the swing angle, and has good stability, high precision and high speed;
(2) The optical filter and the image based on active marker calibration are adopted to identify the measurement angle, so that the influence of ambient light is eliminated, and the anti-interference capability is strong;
(3) The system has simple structure and convenient installation and operation, and solves the problem that the swing angle of the crane hook/the hanging object is difficult to detect quickly on line;
(4) The method provides technical support for further realizing the closed-loop anti-swing control technology of the crane, and has a good application prospect in the intelligent development process of the crane.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a block diagram of a system architecture provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of a marker structure provided by an embodiment of the present invention;
FIG. 3 is a schematic top plan view of a marker provided in accordance with an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an angle detector provided in an embodiment of the present invention;
FIG. 5 is a flow chart of a controller process provided by an embodiment of the present invention;
FIG. 6 is a schematic view of the installation position of the marker and the angle detector on the crane according to the embodiment of the present invention;
FIG. 7 is a schematic diagram of a swing angle calculation swing imaging plane and a swing angle calculation according to an embodiment of the present invention;
FIG. 8 is an image of the light source spot profile after processing in the initialization calibration provided by the embodiment of the invention;
FIG. 9 shows the actual speed of the cart in the second test according to the embodiment of the present invention;
fig. 10 is a measured swing angle curve in test two according to the embodiment of the present invention.
The system comprises a power switch 1, a power indicator lamp 2, a marker shell 3, a light source 4, a first level meter 5, a fixing bolt hole 6, an exhaust fan 7, a collecting device shell 8, an optical filter 9, a lens 10, an industrial camera 11, supporting legs 12, a second level meter 13, a controller 14, a power module 15, a net opening 16 and transparent glass 17.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", "center", "longitudinal", "lateral", "vertical", "horizontal", and the like indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention.
It is noted that the terms "first," "second," and the like in the description of the present invention are used for descriptive purposes only and are not intended to indicate or imply relative importance or order. Further, in the description of the present invention, the meaning of "a plurality" means at least two unless otherwise specified.
As shown in fig. 1 to 6, an embodiment of the present invention provides a crane hook/suspended object swing angle detection system, including: a marker, an angle detector; the angle detector comprises an image acquisition device and a controller;
the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circumference with the radius of R on the upper surface of the marker, and N is more than or equal to 3;
the image acquisition device is used for acquiring a real-time marker image and sending the real-time marker image to the controller, the image acquisition device is vertically and downwards installed on the crane trolley, and the marker is positioned in the center of the visual field of the image acquisition device when the lifting hook is static;
the controller comprises an image preprocessing module, a rope length and circle center detecting module and a swing angle calculating module;
the image preprocessing module is used for preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ，y i ) And radius thereof
The rope length and circle center detection module is used for detecting the radius
Respectively inputting the preset fitting curve functions of the initial calibration radius, the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ，y 0 )；
The swing angle calculation module is used for calculating a value of a swing angle theta through the following formula:
wherein D is p Indicating the actual offset distance of the marker,
k represents a magnification or reduction coefficient, device for selecting or keeping>
Preferably, the included angle between adjacent light sources in the N light sources on the marker is 30-100 degrees, the light sources are invisible light band lamps, and the front end of the image acquisition device is provided with a narrow band filter corresponding to the light source band.
More specifically, as shown in fig. 2, the marker includes a marker housing, a power supply installed in the marker housing, a power switch 1 installed on the marker housing, a power indicator 2, a light source 4, a first level meter 5, and an exhaust fan 7, wherein the exhaust fan, the light source, and the power indicator are all electrically connected to the power supply, the light source switch is used for controlling the on-off of the power circuit, and the exhaust fan is used for dissipating heat of the marker. In this embodiment, 4 holes are formed in the upper surface of the marker housing 3 on the same circumference with the radius R =40mm, as shown in fig. 3, the holes are used for mounting the light source 4, the included angle between the two holes is 45 °, 90 ° and 45 ° from left to right, the light source is preferably an infrared lamp with a wavelength of 940nm, 4 sections of 1.5V batteries are used for supplying power, the marker housing 3 is preferably made of stainless steel or aluminum alloy, and the marker housing 3 is provided with fixing bolt holes 6 for mounting.
The image acquisition device comprises an acquisition device shell 8, an optical filter 9, a lens 10, an industrial camera 11, a second level meter 13 and a power supply module 15, wherein the industrial camera 11, the lens 10 and the optical filter 9 are sequentially arranged from top to bottom, and a controller 14 is integrated in the acquisition device shell 8 and fixed through a supporting leg 12; the industrial camera 11 and the controller 14 are both electrically connected with the power supply module; the bottom of the shell 8 of the collecting device is transparent glass 17. In this embodiment, the filter 9 is a 940nm narrow-band filter corresponding to the light source wavelength band.
When the crane hook/suspended object swing angle detection system is used, calibration needs to be carried out in advance to obtain a fitting curve function of an initial calibration radius, an initial calibration circle center coordinate and a rope length. The specific process is as follows:
a1: marker images of different rope lengths L and in a static state are collected, and n frames of marker images are collected under different rope lengths.
A2: respectively preprocessing each frame of marker image under different rope lengths to respectively obtain the co-circle initial calibration circle center coordinate D under different rope lengths 0 (x 0 ，y 0 ) And initial calibration radius
The method specifically comprises the following steps:
a21: and (3) carrying out noise reduction processing on the marker image: selecting a cross structural element, performing morphological processing on the marker image, and removing a fine region (a region with an area smaller than a preset value) with higher brightness in a light source spot of the marker image;
a22: processing the noise-reduced real-time marker image by adopting a Canny edge detection algorithm to obtain a light source light spot profile corresponding to each light source, namely a light source light spot profile image after the marker image is processed as shown in fig. 8;
a23: processing the outline of each light source light spot by adopting a connected domain function to obtain the circle center coordinate d of each light source light spot i (x i ，y i ) (i =1,2,. N); when a plurality of circle centers corresponding to the light source light spot profiles exist, one circle center is randomly reserved, and other coordinates are removed;
a24: calculating to obtain a real-time circle center coordinate of a common circle based on a three-point common circle method, and further obtaining a radius of the common circle based on the real-time circle center coordinate of the common circle; the method specifically comprises the following steps:
based on the method of three-point co-circle, the centers of the three-point co-circle of the N light sources are co-circle
Get->
Circle center coordinate D j The mean value of the sum of the two is used to obtain the coordinates of the real-time circle center of the common circle>
The radius of the common circle is calculated by the following formula:
a25: respectively solving the co-circle center coordinates corresponding to n frames of marker images under different rope lengths L
And a radius of common circle->
Is in a common circleInitial calibration of circle center coordinates D 0 (x 0 ，y 0 ) And an initial calibration radius>
By averaging, we obtain:
a3: initial radius calibration for a common circle
Circle center coordinate D initially calibrated with a common circle 0 (x 0 ，y 0 ) And fitting a curve with the rope length L to obtain a fitting curve function:
after a fitting curve function of the initial calibration radius, the initial calibration circle center coordinate and the rope length is obtained, the swing angle detection can be performed, and the processing process of the controller is shown in fig. 5.
Furthermore, an embodiment of the present invention further provides a method for detecting a swing angle of a crane hook/suspended object, including:
s1: acquiring a real-time marker image, wherein the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circumference of which the radius is R on the upper surface of the marker, and N is more than or equal to 3; the real-time marker image is acquired by an image acquisition device arranged above the marker;
s2: preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ，y i ) And radius thereof
The method specifically comprises the following steps:
denoising the real-time marker image;
processing the denoised real-time marker image by adopting an edge detection algorithm to obtain a light source light spot profile corresponding to each light source;
processing the outline of each light source light spot by adopting a connected domain function to obtain the circle center coordinate d of each light source light spot i (x i ，y i )(i＝1，2，..，N)；
Calculating to obtain a real-time circle center coordinate of a common circle based on a three-point common circle method, and further obtaining the radius of the common circle based on the real-time circle center coordinate of the common circle; the method specifically comprises the following steps:
based on the method of three-point co-circle, the centers of the three-point co-circle of the N light sources are co-circle
A D j Evaluating whether or not to pick up>
The mean value of the circle centers obtains the coordinates of the circle center of the common circle in real time>
The radius of the common circle is calculated by the following formula:
s3: radius of curvature
Respectively inputting the preset initial calibration radius and the fitting curve function of the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ，y 0 )；
S4: the value of the swing angle θ is calculated by:
wherein D is p Indicating the actual offset distance of the marker,
k represents a magnification or reduction coefficient, device for selecting or keeping>
Fig. 7 is a schematic diagram of swing angle calculation and swing imaging plane and swing angle calculation.
To further understand the technical solution of the present invention, the following description is further provided in conjunction with experiments.
The first test scheme is as follows: a3 m multiplied by 2m crane simulation test bed is set up, a marker is horizontally arranged on the upper surface of a crane hook, a marker power switch is turned on, an angle detector is horizontally arranged on a crane trolley, the marker is positioned in the center of the visual field of the collected real-time image when the crane hook is static, the angle detector is powered on, and a net port 16 connected with a controller is connected with a computer to output a calculated swing angle value.
A ruler was placed on the side of the marker and the marker was manually moved a distance d and the angle calculated and measured, respectively, as shown in table 1.
TABLE 1 swing Angle accuracy test data
As can be seen from Table 1, when the moving distances are respectively 10, 20, 30, \8230; 100, the maximum difference between the calculated angle and the measured angle is 0.056 (30 mm), which is basically within the range of 0.001-0.034, and the overall measurement result shows high accuracy and good stability.
Test scheme two: the test is carried out on the real industrial crane site. Test protocol: the PLC of the crane controls the motor to drive the large trolley to accelerate → uniform → deceleration movement, and the swing angle detection device starts to detect the swing angle after initialization.
As shown in FIG. 9, the actual speed in the cart direction is shown, the abscissa of the figure is time, the ordinate is speed value, the maximum speed in the cart direction is 0.72m/s, and the maximum speed in the cart direction is-0.36 m/s (the minus sign indicates the cart moving direction). As shown in fig. 10, the curve is an actual measurement curve of the swing angle during the moving process of the big car and the small car, wherein the abscissa in the graph is time, the ordinate is a detection swing angle value, the maximum detection swing angle value in the big car direction is 1.729 °, and the maximum detection swing angle value in the small car direction is-0.916 ° (the minus sign indicates that the swing angle is opposite to the moving direction of the small car). The swing angle is gradually increased in the acceleration stage of the big vehicle and the small vehicle, and the swing angles all have peak values after the acceleration stage is finished; then the swing angle of the constant speed section is obviously reduced; the swing angle of the deceleration section is increased again, and the swing angles all have peak values after the deceleration section is finished; and in the parking stage, the swing angle is reduced in the reciprocating swing, the detection result is consistent with the swing in the motion process, and the detection speed is high.
It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (9)
1. A method for detecting the swing angle of a crane hook/hanging object is characterized by comprising the following steps:
acquiring a real-time marker image, wherein the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circle with the radius of R on the upper surface of the marker, and N is more than or equal to 3; the real-time marker image is acquired by an image acquisition device arranged above the marker;
preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ,y i ) And radius thereof
Radius will be
Respectively inputting the preset fitting curve functions of the initial calibration radius, the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ,y 0 )；
The value of the swing angle θ is calculated by:
wherein D is p Indicating the actual offset distance of the marker,
k represents a magnification or reduction coefficient, device for selecting or keeping>
The preset fitting curve function of the initial calibration radius, the initial calibration circle center coordinate and the rope length is obtained by the following method:
collecting marker images with different rope lengths and in a static state;
respectively preprocessing the marker images under different rope lengths to respectively obtain the co-circle initial calibration circle center coordinates D under different rope lengths 0 (x 0 ,y 0 ) And initial calibration radius
Initial radius calibration for a common circle
Circle center coordinate D initially calibrated with a common circle 0 (x 0 ,y 0 ) And fitting a curve with the rope length L to obtain a fitting curve function:
2. the crane hook/sling tilt angle detection method according to claim 1, wherein said pre-processing procedure comprises:
carrying out noise reduction processing on the real-time marker image;
processing the denoised real-time marker image by adopting an edge detection algorithm to obtain a light source light spot profile corresponding to each light source;
processing the outline of each light source light spot by adopting a connected domain function to obtain the circle center coordinate d of each light source light spot i (x i ,y i )(i＝1,2,…,N)；
And calculating to obtain a real-time circle center coordinate of the co-circle based on a three-point co-circle method, and further obtaining the radius of the co-circle based on the real-time circle center coordinate of the co-circle.
3. The method for detecting the swing angle of the crane hook/suspended object according to claim 2, wherein the method for calculating and obtaining the real-time circle center coordinate of the common circle based on the three-point common circle method, and further obtaining the radius of the common circle based on the real-time circle center coordinate of the common circle comprises the following steps:
based on the method of three-point co-circle, the centers of the three-point co-circle of the N light sources are co-circle
Get->
Circle center coordinate D j The mean value of the sum of the two is used to obtain the coordinates of the real-time circle center of the common circle>
The radius of the common circle is calculated by the following formula:
4. the crane hook/hoisted object swing angle detection method as claimed in claim 2, wherein the noise reduction process comprises: selecting a cross structural element, performing morphological processing on the real-time marker image, and removing a fine area with the brightness exceeding a threshold value in a light source spot of the real-time marker image;
when a plurality of circle centers corresponding to the light source light spot profiles are processed by adopting the connected domain function, one light source light spot profile is randomly reserved, and other coordinates are removed.
5. The crane hook/hoisted object swing angle detection method as claimed in claim 4, wherein when marker images at different rope lengths and in a static state are acquired, n frames of marker images are acquired respectively at different rope lengths;
circle center coordinate D of initial calibration of common circle 0 (x 0 ,y 0 ) And initial calibration radius
By averaging, we obtain:
wherein,
represents the co-circle center coordinates corresponding to different frame marker images under the same rope length, and then is matched with the standard rope length>
Representing the corresponding co-circular half of different frame marker images under the same rope lengthAnd (4) diameter.
6. The method for detecting the swing angle of the crane hook/suspended object according to claim 1, wherein the included angle between adjacent light sources in the N light sources on the marker is 30-100 degrees, the light sources are invisible light band lamps, and the front end of the image acquisition device is provided with a light filter corresponding to the light source band.
7. A crane hook/hoisted object swing angle detection system, comprising: a marker, an angle detector; the angle detector comprises an image acquisition device and a controller;
the marker is horizontally arranged on the upper surface of the lifting hook, N light sources are arranged on the same circumference with the radius of R on the upper surface of the marker, and N is more than or equal to 3;
the image acquisition device is used for acquiring a real-time marker image and sending the real-time marker image to the controller, the image acquisition device is vertically and downwards installed on the crane trolley, and the marker is positioned in the center of the visual field of the image acquisition device when the lifting hook is static;
the controller comprises an image preprocessing module, a rope length and circle center detection module and a swing angle calculation module;
the image preprocessing module is used for preprocessing the real-time marker image to obtain the co-circular real-time circle center coordinates D of the N light sources on the marker i (x i ,y i ) And radius thereof
The rope length and circle center detection module is used for detecting the radius
Respectively inputting the preset initial calibration radius and the fitting curve function of the initial calibration circle center coordinate and the rope length to obtain the current rope length l and the initial calibration circle center coordinate D of the common circle 0 (x 0 ,y 0 )；
The swing angle calculation module is used for calculating a value of a swing angle theta through the following formula:
wherein D is p Indicating the actual offset distance of the marker,
k denotes an enlargement or reduction coefficient>
The preset fitting curve function of the initial calibration radius, the initial calibration circle center coordinate and the rope length is obtained by the following method:
collecting marker images with different rope lengths and in a static state;
respectively preprocessing the marker images under different rope lengths to respectively obtain the co-circle initial calibration circle center coordinates D under different rope lengths 0 (x 0 ,y 0 ) And initial calibration radius
Initial radius calibration for a common circle
And the co-circle initial calibration circle center coordinate D 0 (x 0 ,y 0 ) And fitting a curve with the rope length L to obtain a fitting curve function:
8. the crane hook/suspended object swing angle detection system as claimed in claim 7, wherein an included angle between adjacent light sources in the N light sources on the marker is 30 ° to 100 °, and the light sources are invisible light band lamps, and the front end of the image acquisition device is provided with a filter corresponding to the light source band.
9. A crane hook/hoisted object swing angle detection system as claimed in claim 7 or 8, wherein levels are provided on both the marker and the image capture device.
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| CN108830899A (en) * | 2018-06-04 | 2018-11-16 | 哈尔滨工业大学 | A kind of center of circle detection method that the quick self-adapted angle point based on geometrical characteristic combines |
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| CN107055326A (en) * | 2017-04-14 | 2017-08-18 | 上海海事大学 | Many sling bridge crane panning angle measuring devices and the method measured using the device |
| CN108830899A (en) * | 2018-06-04 | 2018-11-16 | 哈尔滨工业大学 | A kind of center of circle detection method that the quick self-adapted angle point based on geometrical characteristic combines |
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