CN117989986B - Cable dynamic displacement monitoring method and system based on combined visual target - Google Patents
Cable dynamic displacement monitoring method and system based on combined visual target Download PDFInfo
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Abstract
The application relates to the technical field of bridge health monitoring, and discloses a method and a system for monitoring dynamic displacement of a inhaul cable based on a combined visual target, wherein the combined visual target is arranged on the inhaul cable of a bridge, and comprises a retroreflection mark target and an infrared LED target; the method comprises the following steps: whether the ambient light is sufficient or not is evaluated, and when the ambient light is insufficient, imaging of a retro-reflection mark target and an infrared LED target on the inhaul cable is obtained; evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index of the retro-reflective marker target and the infrared LED target; obtaining displacement calculated values of the retroreflection marker target and the infrared LED target; and fusing to obtain the displacement of the combined visual target as the displacement of the inhaul cable. And when the ambient light is sufficient, acquiring the displacement of the retroreflection marker target as the displacement of the inhaul cable. According to the application, imaging quality and displacement calculated values of various visual targets are fused to obtain the displacement of the inhaul cable, so that the continuity and measurement accuracy of dynamic displacement monitoring of the inhaul cable are effectively improved, and the illumination robustness is good.
Description
Technical Field
The invention relates to the technical field of bridge health monitoring, in particular to a method and a system for monitoring dynamic displacement of a inhaul cable based on a combined visual target.
Background
The dynamic displacement and derivative mechanical characteristics of the inhaul cable serving as a main force transmission component of the cable bearing bridge are key monitoring contents in the service period of the bridge. The existing technology for measuring the dynamic displacement of the inhaul cable mainly comprises an acceleration quadratic integral method, a microwave radar ranging method and a machine vision plane displacement measuring method.
In the three technologies, the acceleration secondary integration method relies on the installation of an accelerometer at the position of a cable measuring point, a large number of sensor installation and wiring works are needed for monitoring a plurality of cables, and the acceleration data are integrated to obtain dynamic displacement, so that a displacement trend item introduced by measurement noise of the acceleration is unavoidable; in the microwave radar ranging method, the microwave radar has high dynamic displacement precision, and the dynamic displacement of a plurality of inhaul cables can be monitored at the same time when the plurality of inhaul cables are arranged at proper positions, but the section of the inhaul cable to which the measured dynamic displacement belongs is difficult to distinguish on the premise that an angle reflection target is not arranged, and the microwave radar has higher price and is temporarily not applied in a large range; in the machine vision plane displacement measurement method, the dynamic plane displacement of the inhaul cable can be estimated by depending on the boundary edge or angular point characteristics of the inhaul cable, the manufacturing cost is low, the application is more, but the illumination robustness is poor, for example, during the day-night transition period, the illumination has obvious change in a short time, the machine vision plane displacement measurement method is in a transition state of sufficient ambient light and insufficient ambient light, the measurement signal-to-noise ratio is low when the ambient light is insufficient, the machine vision plane displacement measurement method is difficult to adapt to illumination change caused by day-night replacement, and is only suitable for the dynamic displacement monitoring of the inhaul cable in a short time, and is not suitable for continuous monitoring.
Disclosure of Invention
The application provides a guy cable dynamic displacement monitoring method and system based on a combined visual target, which solve the technical problem that the natural visual characteristic identification illumination robustness is poor and the guy cable dynamic displacement monitoring method is not suitable for continuous monitoring in the related technology.
In a first aspect, an embodiment of the present application provides a method for monitoring dynamic displacement of a cable based on a combined visual target, where a plurality of visual targets are set on a cable of a bridge to form the combined visual target, where the visual targets at least include a retroreflection marker target and an infrared LED target;
The method comprises the following steps:
evaluating whether the ambient light is sufficient;
when the ambient light is insufficient, imaging of a retro-reflective marker target on the inhaul cable and imaging of an infrared LED target are obtained;
Evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retroreflection marker target and an imaging quality evaluation index U of the infrared LED target;
obtaining displacement calculation values of the retroreflective marker targets And displacement calculations for the infrared LED targets；
Fusion to obtain displacement of the combined visual targetAs displacement of the cable;
The calculation formula is as follows: ；
And when the ambient light is sufficient, acquiring the displacement of the retroreflection marker target on the inhaul cable as the displacement of the inhaul cable.
With reference to the first aspect, in one embodiment, the visual target further includes a photoresistor, and the photoresistor has a resistance value according to the photoresistorAnd evaluating whether the ambient light is sufficient, and performing automatic switching control of insufficient or sufficient ambient light.
With reference to the first aspect, in one embodiment, a zoom camera is provided to acquire imaging of the retro-reflective marker target and imaging of the infrared LED target on the cable, a field of view of the zoom camera covering the combined visual target.
With reference to the first aspect, in one embodiment, obtaining an image of the retro-reflective marker target and an image of the infrared LED target on the cable comprises:
Identifying the position and size of a retro-reflective marker target on the cable;
And the visual field center of the zoom camera is adjusted to be appointed for the visual target, so that imaging of the retro-reflection mark target and imaging of the infrared LED target on the inhaul cable are obtained.
With reference to the first aspect, in an embodiment, the evaluating the local imaging quality of the combined visual target to obtain the imaging quality evaluation index Q of the retro-reflective marker target and the imaging quality evaluation index U of the infrared LED target includes:
the imaging quality evaluation index Q of the retroreflection marker target is defined as the corner feature quality evaluation index of the retroreflection marker target;
The calculation formula is as follows: ；
Wherein R meau is the measured value of the angular point response of the ROI area; r ref is the ROI region angular point response reference value;
the imaging quality evaluation index U of the infrared LED target is defined as spot edge gray level uniformity;
The calculation formula is as follows: ；
Wherein I max is the light spot edge pixel band Is the pixel gray maximum value of (1); i min is the light spot edge pixel bandIs a minimum value of pixel gray scale of (c).
With reference to the first aspect, in an implementation manner, the ROI area corner response reference value R ref is an average value of ROI area corner responses R of a reference time period, and the step of obtaining the ROI area corner responses R includes:
Establishing the ROI area A gray level change feature matrix M;
m is expressed as: ；
Wherein, ROI area in x-direction for pixels of different positionsThe gray-scale gradient is such that,ROI area in y-direction for pixels of different locationsGray scale gradient;
Calculating the eigenvalue of M AndTo obtain the ROI areaCorner response R;
The calculation formula is as follows: 。
in a second aspect, an embodiment of the present application further provides a cable dynamic displacement monitoring system based on a combined visual target, including:
the visual targets are arranged on the inhaul cable of the bridge to form a combined visual target, and at least comprise a retroreflection mark target and an infrared LED target;
a zoom camera configured to: acquiring imaging of a retro-reflective marker target and imaging of an infrared LED target on the inhaul cable, wherein the visual field of the zoom camera covers the combined visual target;
an imaging quality assessment module configured to: evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retroreflection marker target and an imaging quality evaluation index U of the infrared LED target;
a displacement calculation module configured to: obtaining displacement calculation values of the retroreflective marker targets And displacement calculations for the infrared LED targets；
A fusion calculation module configured to: fusion to obtain displacement of the combined visual targetAs displacement of the cable;
The calculation formula is as follows: 。
With reference to the second aspect, in one embodiment, the cable is provided with a target clamp, the target clamp fixes the combined visual target and the cable, the target clamp is provided with two surfaces which are adjacently arranged, the retroreflection mark targets are arranged on one surface, and the retroreflection mark targets are a plurality of binary coded retroreflection marks; the infrared LED targets are arranged on the other surface, and the infrared LED targets are a plurality of infrared LED lamp beads.
With reference to the second aspect, in one embodiment, the visual target further comprises a photoresistor for assessing whether ambient light is sufficient, the photoresistor being disposed proximate to the retroreflective marker target.
With reference to the second aspect, in one embodiment, an infrared light panel is disposed on the zoom camera.
The technical scheme provided by the embodiment of the application has the beneficial effects that:
The application provides a cable dynamic displacement monitoring method based on a combined visual target, which comprises the steps of firstly arranging a plurality of visual targets to form the combined visual target, and carrying out optimal visual target positioning selection according to the site illumination condition of a bridge and the day-night replacement condition, so that the imaging quality can be ensured no matter whether the ambient light is sufficient or insufficient; secondly, whether the ambient light is sufficient or not is evaluated, automatic switching is conveniently carried out according to different modes of the ambient light, and when the ambient light is sufficient, the displacement of the inhaul cable is determined only through the retroreflection mark target; when the ambient light is insufficient, the infrared LED targets are synchronously used as combined visual targets, and a better signal-to-noise ratio is provided under the same observation distance; and moreover, the imaging quality and the displacement calculated values of various visual targets are fused to obtain the displacement of the inhaul cable, so that the dynamic displacement calculated result meets the requirement of continuous acquisition, the continuity and the measurement precision of inhaul cable dynamic displacement monitoring are effectively improved, and the illumination robustness is good.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic layout diagram of a cable dynamic displacement monitoring system based on a combined visual target according to an embodiment of the invention.
Fig. 2 is a schematic structural view of a visual target mounted on a cable according to an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a visual target according to an embodiment of the invention.
Fig. 4 is a diagram showing a comparison of corner targets and dot targets in an embodiment of the present invention.
Fig. 5 is a schematic structural diagram of a zoom camera according to an embodiment of the invention.
In the figure: 1. a guy cable; 2. a visual target; 21. a retroreflective marker target; 22. an infrared LED target; 23. a target clamp; 24. a photoresistor; 3. a zoom camera; 4. rotating the cradle head; 5. an infrared lamp panel; 6. and calculating the terminal.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The embodiment of the application provides a method and a system for monitoring dynamic displacement of a guy cable based on a combined visual target, which can solve the technical problem that the continuous monitoring is not suitable due to poor illumination robustness of natural visual feature identification existing in a machine visual plane displacement measurement method in the related technology.
Fig. 1 to 3 show an arrangement schematic diagram of a cable dynamic displacement monitoring system based on a combined visual target according to an embodiment of the invention. Fig. 2 is a schematic structural view of a visual target mounted on a cable according to an embodiment of the present invention. Fig. 3 is a schematic structural diagram of a visual target according to an embodiment of the invention.
The embodiment provides a cable dynamic displacement monitoring method based on a combined visual target, wherein a plurality of visual targets 2 are arranged on a cable 1 of a bridge to form the combined visual target, and the visual targets 2 at least comprise a retroreflection mark target 21 and an infrared LED target 22;
The method comprises the following steps:
Step S1, evaluating whether the ambient light is sufficient;
step S2, when the ambient light is insufficient,
S21, imaging the retroreflection marker target 21 and imaging the infrared LED target 22 on the inhaul cable 1 are obtained;
step S22, evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retroreflection marker target 21 and an imaging quality evaluation index U of the infrared LED target 22;
In an embodiment, the retro-reflective marker targets 21 and the infrared LED targets 22 in the combined targets are at different locations in the captured image, respectively, so that regions of interest (ROIs) can be extracted in the captured image for analysis of corresponding portions of each region of interest (ROI), which can be manually selected in advance by manually setting up the camera field of view.
Specifically, two partial images (i.e., ROI areas) may be extracted from the captured image, wherein one partial image contains the retroreflective marker target 21 and the other partial image contains the infrared LED target 22. Correspondingly, because the displacement of the inhaul cable is not too large, the ROI area slightly expands a part of pixel area outwards after the target position of the current frame is selected.
Step S23, respectively identifying imaging of the retroreflection marker target 21 and imaging of the infrared LED target 22 to obtain displacement calculation value of the retroreflection marker target 21And displacement calculations for the infrared LED targets 22；
Step S24, fusing to obtain the displacement of the combined visual targetAs displacement of the cable 1;
The calculation formula is as follows: ；
And S3, when the ambient light is sufficient, acquiring imaging of the retroreflection marker target 21 on the inhaul cable 1, and identifying imaging of the retroreflection marker target 21 to acquire displacement of the retroreflection marker target 21 on the inhaul cable 1 as displacement of the inhaul cable 1.
The embodiment provides a cable dynamic displacement monitoring method based on a combined visual target, which comprises the steps of firstly arranging a plurality of visual targets to form the combined visual target, and carrying out optimal visual target positioning selection according to the on-site illumination condition of a bridge and the day-night replacement condition, so that the imaging quality can be ensured no matter whether the ambient light is sufficient or insufficient; secondly, whether the ambient light is sufficient or not is evaluated, automatic switching is conveniently carried out according to different modes of the ambient light, and when the ambient light is sufficient, the displacement of the inhaul cable is determined only through the retroreflection mark target; when the ambient light is insufficient, the infrared LED targets are synchronously used as combined visual targets, and a better signal-to-noise ratio is provided under the same observation distance; and moreover, the fusion weight is dynamically determined according to the real-time imaging quality and the displacement calculated values of various visual targets to obtain the displacement of the inhaul cable, so that the dynamic displacement calculated result meets the requirement of continuous acquisition, the continuity and the measurement precision of inhaul cable dynamic displacement monitoring are effectively improved, and the illumination robustness is good.
Fig. 4 is a diagram showing a corner target and a dot target in comparison with each other according to an embodiment of the present invention, as shown in fig. 1 to 4.
A plurality of visual targets 2 are arranged on the inhaul cable 1 of the bridge to form a combined visual target, and the visual targets 2 at least comprise a retroreflection mark target 21 and an infrared LED target 22.
Through the scheme, the retro-reflection mark target 21 can be used for inhaul cable vibration imaging and displacement calculation under different illumination conditions in all weather through the retro-reflection angular point array image; the infrared LED targets 22 are imaged by self-luminescence into dots, and are also used for cable vibration imaging and displacement calculation. Although the infrared LED targets 22 may be difficult to image dots when the ambient light is sufficient, such as at a time point when the illumination condition is strong in the daytime, and cannot participate in the cable displacement calculation, when the ambient light is insufficient, the cable dynamic displacement monitoring effect fused with the infrared LED targets is better, and meanwhile, the requirements of the target imaging quality stability and the cable measurement precision are met.
In one embodiment, the cable 1 is provided with a target clamp 23, the target clamp 23 fixes the combined visual target and the cable 1, the target clamp 23 has two surfaces which are adjacently arranged, the retro-reflective marker target 21 is arranged on one surface, and the infrared LED target 22 is arranged on the other surface.
In one embodiment, the retroreflective marker targets 21 are a plurality of binary coded retroreflective markers; the infrared LED targets 22 are a plurality of infrared LED light beads.
Through the scheme, the binary coded retroreflective sign is used as an angular point target, a pattern with unique coding information is provided, and the binary coded retroreflective sign can be used for accurately positioning a specific number of inhaul cables when a plurality of inhaul cables appear in a visual field; the infrared LED lamp beads are used as dot targets and also used for inhaul cable vibration imaging and displacement calculation, the infrared LED lamp beads are active light sources from the light source angle, the binary coded retroreflective markers are passive light sources, and the signal to noise ratio of the infrared LED lamp beads can be better under the same observation distance. Although the infrared LED lamp beads can be difficult to image dots when the ambient light is sufficient, such as a time point with strong illumination conditions in the daytime, and can not participate in the cable displacement calculation, the cable dynamic displacement monitoring effect fused with the infrared LED targets is better when the ambient light is insufficient.
The steps are described and illustrated in detail below.
In one embodiment, in step S1, the visual target 2 further includes a photoresistor 24, and the resistance value of the photoresistor 24 is determinedAnd evaluating whether the ambient light is sufficient, and performing automatic switching control of insufficient or sufficient ambient light. The photoresistor 24 is disposed proximate to the retroreflective marker target 21.
Through the scheme, because the measurement precision and the stability of different visual targets are different under different ambient light conditions, whether the ambient light is sufficient or not is estimated according to the photoresistors which are very sensitive to the light, the estimation result is more accurate, automatic switching control is conveniently carried out on the measurement modes of the sufficient and insufficient ambient light, so that the cable displacement measurement under different ambient light conditions is adapted, and the cable displacement monitoring automation degree and the monitoring effect are improved.
In an embodiment, in step S21, the zoom camera 3 is set to acquire imaging of the retro-reflective marker target 21 and imaging of the infrared LED target 22 on the cable 1, the field of view of the zoom camera 3 covering the combined visual target.
The zoom camera 3 is further arranged on the rotary tripod head 4, so that the angle can be conveniently adjusted.
Through the scheme, imaging of various visual targets 2 is accurately obtained through the zoom camera 3.
Fig. 5 is a schematic structural diagram of a zoom camera according to an embodiment of the invention.
In one embodiment, the zoom camera 3 is provided with an infrared light panel 5.
Through the scheme, the infrared lamp panel 5 is utilized to supplement light for the retroreflection marker target 21 at night, so that the method is further suitable for inhaul cable vibration imaging and displacement calculation under different illumination conditions.
In one embodiment, step S21, acquiring the imaging of the retroreflective marker target 21 and the imaging of the infrared LED target 22 on the cable 1 includes:
Step S211, the position and the size of the retroreflective marker target 21 on the cable 1 are identified.
Specifically, the relative position of the combined visual target mounted on each cable 1 to the initial position of the zoom camera 3 is determined, the approximate positions of the cables 1 are configured in the initialization stage, and the rotary holder 4 rotates according to the observed approximate positions of the various visual targets 2 on the cables 1; identifying the position and the size of the coded marker pixels on the retroreflective marker target 21 on the inhaul cable 1, such as the identification method: firstly, self-adaptive threshold segmentation is carried out; searching the outline, and searching the connected domain by using Union-find; performing straight line fitting on the outline, and searching candidate convex quadrilaterals; finally decoding the quadrangle to identify the target ID, and other identification methods can be adopted.
Step S212, the visual field center of the zoom camera 3 is adjusted to the appointed visual target 2, so that imaging of the retro-reflective marker target 21 and imaging of the infrared LED target 22 on the inhaul cable 1 are obtained.
The visual field center of the zoom camera 3 is adjusted to the appointed visual target 2, and the effective resolution of the visual target 2 is precisely controlled to the optimal resolution.
In one embodiment, step S22, evaluating the local imaging quality of the combined visual target to obtain the imaging quality evaluation index Q of the retro-reflective marker target and the imaging quality evaluation index U of the infrared LED target includes:
Step S221, defining an imaging quality evaluation index Q of the retroreflection marker target 21 as an angular point characteristic quality evaluation index of the retroreflection marker target 21;
The calculation formula is as follows: ；
Wherein R meau is the measured value of the angular point response of the ROI area; r ref is the ROI region corner response reference value.
Specifically, the ROI (Region of Interest) region refers to a specific region that is of interest to the user and requires a focus on in image processing. In the field of machine vision and image processing, the ROI area may be delineated in a number of ways, such as a box, circle, ellipse, or irregular polygon. Using ROI areasThe processing time can be effectively reduced and the accuracy can be improved. The region of interest (ROI) is manually selected in advance by manually setting the field of view of the zoom camera. Because the inhaul cable displacement is not too large, the ROI area slightly expands a part of pixel area outwards after the target position of the current frame is selected.
The angular point response reference value of the ROI area takes an R mean value of a reference time period (namely, a time period with better imaging quality) as the reference value, and the reference time period is determined empirically.
In an embodiment, obtaining the ROI region corner response R includes:
Establishing an ROI region A gray level change feature matrix M;
m is expressed as: ；
Calculating the eigenvalue of M AndTo obtain the ROI areaCorner response R;
Wherein, ROI area in x-direction for pixels of different positionsThe gray-scale gradient is such that,ROI area in y-direction for pixels of different locationsGray scale gradient;
The calculation formula is as follows: 。
Wherein, AndThe displacement is obtained by analyzing the two-dimensional coordinates of the target control point under the image coordinate system based on the image data and converting the coordinates.
Step S222, defining an imaging quality evaluation index U of the infrared LED target 22 as spot edge gray level uniformity;
The calculation formula is as follows: ；
Wherein I max is the light spot edge pixel band Is the pixel gray maximum value of (1); i min is the light spot edge pixel bandIs a minimum value of pixel gray scale of (c).
Through the scheme, the local imaging quality of the combined visual target is evaluated, so that the two visual target displacement data are further fused to obtain final inhaul cable displacement as a basis.
In one embodiment, step S23, respectively, identifies the imaging of the retroreflective marker target 21 and the imaging of the infrared LED target 22 to obtain a displacement calculation of the retroreflective marker target 21And displacement calculations for the infrared LED targets 22Comprising the following steps:
In step S231, the intersection point of the optical axis and the photosensitive element of the camera is taken as the origin O, and the x and y axes are established parallel to the two orthogonal sides through the O point.
Because the imaging point x and y pixel coordinates of the visual target 2 on the photosensitive element can change along with the movement of the inhaul cable 1, the imaging point x and y pixel coordinates of the visual target 2 on the photosensitive element at the original position of the inhaul cable 1 are taken as reference coordinates, and the imaging point x and y pixel coordinates of the visual target 2 on the photosensitive element change along with the movement of the inhaul cable 1 to represent the displacement of the visual target.
Specifically, both visual targets are in the camera view (i.e., zoom camera 3), so one xoy coordinate system is shared.
Step S232, calculating the geometrical center position of the corner group in the retroreflection marker target 21 through a corner recognition algorithmObtaining displacement calculation value of the retroreflection marker target 21 according to the change of the geometric center position two-dimensional pixel coordinates of the corner group。
Step S233, calculating the geometrical center position of the light spot in the infrared LED target 22 through an ellipse recognition algorithmObtaining displacement calculation value of infrared LED target 22 according to two-dimensional pixel coordinate change of geometrical center position of light spot。
Through the scheme, the displacement calculated value of the combined visual target is obtained by imaging of the identified visual target for subsequent fusion, and of course, the displacement calculated value of the combined visual target can also be obtained by adopting other algorithms, which belongs to the prior art and is not described in detail herein.
The application also provides a system for monitoring dynamic displacement of the inhaul cable based on the combined visual target, which comprises:
a plurality of visual targets 2 arranged on the inhaul cable 1 of the bridge to form a combined visual target, wherein the visual targets 2 at least comprise a retroreflection mark target 21 and an infrared LED target 22;
a zoom camera 3 configured to: acquiring imaging of a retro-reflective marker target 21 and imaging of an infrared LED target 22 on the inhaul cable 1, and covering a combined visual target by a visual field of the zoom camera 3;
An imaging quality assessment module configured to: evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retro-reflective marker target 21 and an imaging quality evaluation index U of the infrared LED target 22;
A displacement calculation module configured to: imaging of the retroreflective marker target 21 and imaging of the infrared LED target 22 are separately identified to obtain displacement calculations of the retroreflective marker target 21 And displacement calculations for the infrared LED targets 22；
A fusion calculation module configured to: fusion to obtain displacement of combined visual targetsAs displacement of the cable 1;
The calculation formula is as follows: 。
In one embodiment, the cable 1 is provided with a target clamp 23, the target clamp 23 fixes the combined visual target and the cable 1, the target clamp 23 has two surfaces which are adjacently arranged, the retro-reflective marker target 21 is arranged on one surface, and the infrared LED target 22 is arranged on the other surface.
In one embodiment, the retroreflective marker targets 21 are a plurality of binary coded retroreflective markers; the infrared LED targets 22 are a plurality of infrared LED light beads.
In one embodiment, the visual target 2 further includes a photoresistor 24 for assessing whether the ambient light is sufficient, the photoresistor 24 being disposed proximate to the retroreflective marker target 21.
In one embodiment, the zoom camera 3 is provided with an infrared light panel 5.
The zoom camera 3 is connected with a computing terminal 6, and an imaging quality evaluation module, a displacement computing module and a fusion computing module are integrated in the computing terminal 6, and the computing terminal 6 is used for analyzing image data, imaging automatic control, related computation and the like.
The function implementation of each module in the cable dynamic displacement monitoring system based on the combined visual target corresponds to each step in the cable dynamic displacement monitoring method embodiment based on the combined visual target, and the function and the implementation process of the module are not described in detail herein.
In the description of the present application, it should be noted that the azimuth or positional relationship indicated by the terms "upper", "lower", etc. are based on the azimuth or positional relationship shown in the drawings, and are merely for convenience of describing the present application and simplifying the description, and are not indicative or implying that the apparatus or element in question must have a specific azimuth, be constructed and operated in a specific azimuth, and thus should not be construed as limiting the present application. Unless specifically stated or limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
It should be noted that in the present application, relational terms such as "first" and "second" and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
In the description of the embodiments of the present application, unless otherwise indicated, "/" means or, for example, a/B may represent a or B; the text "and/or" is merely an association relation describing the associated object, and indicates that three relations may exist, for example, a and/or B may indicate: the three cases where a exists alone, a and B exist together, and B exists alone, and furthermore, in the description of the embodiments of the present application, "plural" means two or more than two.
The foregoing is merely exemplary of embodiments of the present application to enable those skilled in the art to understand or practice the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. The cable dynamic displacement monitoring method based on the combined visual target is characterized in that a plurality of visual targets (2) are arranged on a cable (1) of a bridge to form the combined visual target, and the visual targets (2) at least comprise a retroreflection mark target (21) and an infrared LED target (22);
The method comprises the following steps:
evaluating whether the ambient light is sufficient;
Acquiring imaging of a retro-reflective marker target (21) and imaging of an infrared LED target (22) on the cable (1) when the ambient light is insufficient;
Evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retro-reflective marker target (21) and an imaging quality evaluation index U of the infrared LED target (22);
obtaining a displacement calculation of the retroreflective marker target (21) And displacement calculations of the infrared LED targets (22)；
Fusion to obtain displacement of the combined visual targetAs a displacement of the pull cable (1);
The calculation formula is as follows: ；
When the ambient light is sufficient, acquiring the displacement of a retro-reflective marker target (21) on the inhaul cable (1) as the displacement of the inhaul cable (1);
Said evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retro-reflective marker target (21) and an imaging quality evaluation index U of the infrared LED target (22) comprises:
the imaging quality evaluation index Q of the retroreflection marker target (21) is defined as a corner feature quality evaluation index of the retroreflection marker target (21);
The calculation formula is as follows: ；
Wherein R meau is the measured value of the angular point response of the ROI area; r ref is the ROI region angular point response reference value;
The ROI area angular point response reference value R ref is a mean value of ROI area angular point response R of a reference time period, and the step of obtaining the ROI area angular point response R includes:
Establishing the ROI area A gray level change feature matrix M;
m is expressed as: ；
Wherein, ROI area in x-direction for pixels of different positionsThe gray-scale gradient is such that,ROI area in y-direction for pixels of different locationsGray scale gradient;
Calculating the eigenvalue of M AndTo obtain the ROI areaCorner response R;
The calculation formula is as follows: ；
the imaging quality evaluation index U of the infrared LED target (22) is defined as spot edge gray level uniformity;
The calculation formula is as follows: ；
Wherein I max is the light spot edge pixel band Is the pixel gray maximum value of (1); i min is the light spot edge pixel bandIs a minimum value of pixel gray scale of (c).
2. The method for monitoring dynamic displacement of a guy cable based on combined visual target according to claim 1, wherein the visual target (2) further comprises a photoresistor (24), and the resistance value of the photoresistor (24) is used forAnd evaluating whether the ambient light is sufficient, and performing automatic switching control of insufficient or sufficient ambient light.
3. A method of dynamic displacement monitoring of a cable based on combined visual targets according to claim 1, wherein a zoom camera (3) is provided to acquire imaging of a retro-reflective marker target (21) and imaging of an infrared LED target (22) on the cable (1), the field of view of the zoom camera (3) covering the combined visual targets.
4. A combined visual target-based cable dynamic displacement monitoring method according to claim 3 wherein acquiring imaging of a retro-reflective marker target (21) and imaging of an infrared LED target (22) on the cable (1) comprises:
Identifying the position and size of a retro-reflective marker target (21) on the cable (1);
The visual field center of the zoom camera (3) is adjusted to be appointed to the visual target (2) so as to obtain imaging of a retro-reflection mark target (21) and imaging of an infrared LED target (22) on the inhaul cable (1).
5. A combined visual target-based cable dynamic displacement monitoring system, applying the combined visual target-based cable dynamic displacement monitoring method as claimed in any one of claims 1 to 4, characterized in that the system comprises:
A plurality of visual targets (2) arranged on a guy cable (1) of the bridge to form a combined visual target, wherein the visual targets (2) at least comprise a retroreflection mark target (21) and an infrared LED target (22);
A zoom camera (3) configured to: acquiring imaging of a retro-reflective marker target (21) and imaging of an infrared LED target (22) on the inhaul cable (1), wherein the visual field of the zoom camera (3) covers the combined visual target;
An imaging quality assessment module configured to: evaluating the local imaging quality of the combined visual target to obtain an imaging quality evaluation index Q of the retro-reflective marker target (21) and an imaging quality evaluation index U of the infrared LED target (22);
a displacement calculation module configured to: obtaining a displacement calculation of the retroreflective marker target (21) And displacement calculations of the infrared LED targets (22)；
A fusion calculation module configured to: fusion to obtain displacement of the combined visual targetAs displacement of the cable;
The calculation formula is as follows: 。
6. The cable dynamic displacement monitoring system based on combined visual targets as claimed in claim 5, wherein a target clamp (23) is arranged on the cable (1), the target clamp (23) is used for fixing the combined visual targets with the cable (1), the target clamp (23) is provided with two adjacently arranged surfaces, the retroreflection mark target (21) is arranged on one surface, and the retroreflection mark targets (21) are a plurality of binary coded retroreflection marks; the infrared LED targets (22) are arranged on the other surface, and the infrared LED targets (22) are a plurality of infrared LED lamp beads.
7. The combined visual target-based cable dynamic displacement monitoring system according to claim 6, wherein the visual target (2) further comprises a photoresistor (24) for assessing whether ambient light is sufficient, the photoresistor (24) being disposed in proximity to the retro-reflective marker target (21).
8. The guy cable dynamic displacement monitoring system based on the combined visual target as claimed in claim 5, wherein an infrared lamp panel (5) is arranged on the zoom camera (3).
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| CN115861444A (en) * | 2022-12-23 | 2023-03-28 | 易思维（杭州）科技有限公司 | Visual sensor external parameter calibration method based on three-dimensional target |
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