RU2492420C2 - Method of determining spatial position of object and apparatus for implementing said method - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: when implementing the method, control marks are mounted at control points of the object, radiation from which forms exposure distribution in the image plane of the photodetector device. Coordinates of control marks in an instrument coordinate system are determined from the obtained image in one spectral range. The position of the instrument coordinate system relative an external system is determined. The spatial position of the object is determined from coordinates of control marks recalculated from the instrument coordinate system to the external coordinate system. Further, exposure distribution in a spectral range different from the first is determined. Coordinates of centres of exposure distribution in each of the two spectral ranges are compared. The refraction error value is determined and then subtracted from the obtained coordinates of control marks in the instrument coordinate system. In the apparatus, at least one point radiator of one control mark is in form of a white light radiator. The photodetector device has at least one photodetector in form of a matrix optical radiation detector, on each spatial element of which there is a light filter of one of at least two different spectral ranges.

EFFECT: high measurement accuracy.

3 cl, 3 dwg

Description

The invention relates to measuring technique and is intended to measure the spatial position of the object by remote measurement of the coordinates of the control marks attached to it. Moreover, the invention allows monitoring the state of man-made structures and, therefore, to prevent the occurrence of man-made disasters. The invention can be used to prevent the destruction of dams, bridges, building structures (foundations of buildings, roofs, etc.), tunnels, as well as the prevention of railway accidents, accidents at mines, plane crashes, etc.

The closest in technical essence to the claimed invention is a method of measuring the spatial position of an object using a geodetic measuring device (US 2010/0119161 A1 G06K 9/68; G01C 15/00 from 05/13/2010).

This measurement method is as follows. At controlled points of the object, at least three reference marks are fixed, the radiation from which forms the distribution of irradiation in the image plane of the photodetector. The obtained images determine the coordinates of the control marks in the instrument coordinate system. Next, find at least two common marks between the measured control marks and the reference marks, the position of which is known in the external coordinate system. The position of the common marks determines the position of the instrument coordinate system in the external system, and the spatial position of the object is determined by the coordinates of the control marks, recounted from the instrument coordinate system to the external coordinate system.

The disadvantages of the considered method are the lack of measurement of the refractive component of the measurement error, which in the presence of a temperature gradient along the measurement path can significantly reduce the measurement accuracy;

the complexity of the search for reference marks among the set of control, which with a significant number of tags significantly reduces performance; as well as low automation of measurements.

The prior art device for measuring the spatial position of an object described in patent WO 01/88470 A1, G01B 11/00 of 11/22/2001, which, by the totality of the features, is closest to the claimed invention and can be taken as a prototype. This device includes at least one reference mark made in the form of at least one point emitter placed on the controlled object, a photodetector optically coupled to a control mark, containing an optical system in the focal plane of which there is a photodetector, the output of which is connected to the input of the processing unit , and a label control unit, the input of which is connected to the first output of the processing unit.

The main disadvantage of this device is the lack of the ability to measure the refractive component of the measurement error:

Therefore, the objective of the present invention is to develop a new method for measuring the spatial position of the object and device for its implementation, which would ensure the achievement of the following technical result, namely improving the accuracy of measurement.

The solution of the problem with the achievement of the specified technical result consists in the fact that in the method of measuring the spatial position of the object, which consists in the fact that at the controlled points of the object control marks are fixed, the radiation from which forms the distribution of irradiation in the image plane of the photodetector, fixing the distribution obtained in one of spectral ranges, an image is obtained that determines the coordinates of the spatial position of the control marks in the instrument the coordinate system (UCS), finding among the coordinates of the control marks the coordinates of those points whose position is known in the external coordinate system, determine the position of the instrument coordinate system relative to the external system, and the spatial position of the object is determined by the coordinates of the control marks recounted from the instrument coordinate system to the external system of coordinates, new is that they additionally fix the distribution of irradiation in a spectral range other than the first, comparing the coordinates of the centers of irradiation limits in each of the two spectral ranges for at least one label determine the value of the refractive error:

$$\text{Δx}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{x}\left({\text{λ}}_{\text{one}}\right)-\text{x}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

$$\text{Δy}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{y}\left({\text{λ}}_{\text{one}}\right)-\text{y}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

where n (λ), n (λ ₁ ), n (λ ₂ ) are the refractive indices of the air path at the measurement wavelength and in the selected spectral ranges, respectively, (x (λ ₁ ), y (λ ₁ )), (x ( λ ₂ ), y (λ ₂ )) are the coordinates of the center of the distribution of irradiation in the image of the label in the selected spectral ranges, M is the coefficient of conversion of coordinates from the image space to the space of objects, from the obtained coordinate values of the spatial position of the control marks in the instrument coordinate system, the value of the refraction inaccuracies.

A variant is possible, the development of the main technical solution of which consists in the fact that the method of measuring the spatial position additionally fixes the distribution of background irradiation that does not contain irradiation from control marks, comparing it with the distribution of irradiation obtained earlier in the same spectral range, they reveal different areas that take for the image labels, which determine the coordinates of the spatial position of the control labels in the instrument coordinate system.

In the device for measuring the spatial position of an object, including at least one reference mark made in the form of at least one point emitter placed on the controlled object, a photodetector optically coupled to a control mark containing an optical system in the focal plane of which there is a photodetector, the output of which connected to the input of the processing unit, and the label control unit, the input of which is connected to the first output of the processing unit, is new, that at least one point ny radiator one reference mark is in the form of white emitter and photodetector comprises at least one photodetector provided in the form of a matrix of optical radiation receiver, on each spatial filter element which is deposited one of at least two different spectral ranges.

The applicant has conducted a patent search on this topic and the claimed combination of essential features has not been identified. Therefore, the present invention can be recognized as new.

The invention is illustrated by drawings.

Figure 1 shows the structural diagram of the inventive device.

1 - control mark (KM)

2 - photodetector (FU)

3 - optical system (OS)

4 - photodetector (FP)

5 - light filter (SF)

6 - processing unit (BO)

7 - label control unit (BOOM)

The device contains active control marks 1, rigidly fixed at controlled points of the object. Each control mark 1 contains at least one point emitter, and is optically coupled to a photodetector 2, consisting of an optical system 3, in the focal plane of which there is a photodetector 4, on each spatial element of which a filter 5 of one of at least two different spectral ranges. For example, a color matrix photodetector can be used, the order of which filters is made according to the Bayer scheme. The output of the photodetector 4 is connected to the first input of the processing unit 6, the first output of which is connected to the input of the label control unit 7, which determines the operation mode of the control labels 1, and the other output is designed to connect to an external device, for example, to an alarm device or to a server that collects information about the state of the object from sensors of various types.

Figure 2 shows the principle of combating interference using the inter-frame difference, where a is an image containing only background irradiance, b is an image containing also irradiation from the reference mark, c is the resulting image containing only the reference mark image.

Figure 3 presents the principle of measuring the refractive component of the error. The filters 5, the processing unit 6 and the label control unit 7 are not shown.

The radiation from the point emitter of the reference mark 1, passing along an optical path of length L, is subjected to refraction as a result of the presence of a temperature gradient T. Since the radiation of different wavelengths deviates differently as a result of the action of refraction, then in the plane of the photodetector 4 located at a distance f 'from the optical system, each spectral channel forms its own image of the emitter of the reference mark 1. If the effect of refraction is not taken into account, then the coordinate recount emitter of control mark 1 from the space of objects to the space of images will lead to erroneous results - 1 '. In this case, the error value for each spectral channel will be different. However, by measuring the deviations of the image for the two spectral channels y (λ ₁ ) and y (λ ₂ ), it is possible to calculate the magnitude of the error that arises under the given conditions for the required wavelength and make a corresponding correction to the measurements.

A method of measuring the spatial position of an object and a device for its implementation are as follows.

At least three control marks 1 are fixed at the control points of the object, each of which contains at least one point emitter optically coupled to a photo-receiving device 2. The presence of several emitters in the control mark 1 allows one to calculate the coordinate of the distance to the measurement object without using range-finding channels, as well as to increase the noise immunity of the device, since such a performance of check mark 1 brings additional information, which allows the use of special algorithm s recognition. At least two reference marks 1 are fixed at points whose coordinates are a priori known in an external coordinate system (for example, the design coordinate system of a building). These reference marks are reference. To increase the accuracy of determining the relative position of the instrument and external coordinate systems, reference marks are set at points spaced at a maximum distance within the field of view of the photodetector 2.

Since the control marks 1 are optically coupled to the photodetector 2, their radiation passing through the optical system 3 forms an irradiation distribution in the image plane of the photodetector 2, in which the photodetector 4 is installed, made in the form of a matrix receiver of optical radiation, on each spatial element of which is applied 5 filter of red, blue or green spectral regions. The signal from the processing unit 6, the photodetector 2 captures the formed distribution of irradiation. Processing unit 6 sequentially generates two frame lock signals. The first is at the moment when all the control marks 1 located in the field of view of the photodetector 2 are turned off. Thus, the photodetector 2 captures an image containing only background irradiation. The second - at the time when all the control marks 1 in the field of view of the photodetector 2 are turned on. Thus, the second image contains, in addition to the same background irradiation, also the irradiation from the reference marks 1. Since the photodetector 4 is made in the form of a color matrix, when it fixes the distribution of irradiation, three images are obtained in different spectral ranges (red, blue and green) . One of these images (for example, in the red range) is used to combat interference using the inter-frame difference (Fig. 2), and the other (in the blue or green range) is used to calculate the refractive component of the error. The captured images are stored in the memory of the processing unit 6. The control marks 1 are turned on and off by the label control unit 7 by a command from the processing unit 6. In addition, the communication between the processing unit 6 and the label control unit 7 allows you to adjust the brightness of the sources of the control mark 1, increasing their visibility against the background of the environment.

The fight against interference using the inter-frame difference is as follows (figure 2). Processing unit 6 compares two images stored in memory - one image obtained by the first command from processing unit 6 (contains only background irradiation (Fig. 2, a), for example, in the red channel, and the second image obtained in the same the spectral range, but according to the second command from the processing unit 6 (contains irradiation and from the control marks 1 (Fig.2, b). In the processing unit 6, one image subtract one image from another, thereby leaving on the resulting image (Fig.2, c) only distinguishing These regions are, with a high degree of probability, precisely images of control marks 1. Next, the coordinates of the spatial position of the control marks in the instrument coordinate system are determined by the coordinates of the centers of the images of control marks 1.

After that, one of the images obtained by the second command from the processing unit 6, but in a different spectral range (for example, in the blue channel) also finds the coordinates of the centers of the reference marks 1. Their location is not difficult, since the images of the reference marks 1 found earlier in another spectral channel, located in the same spatial region. For at least one reference mark 1 in the processing unit 6, the difference in coordinates between the centers of its images in each of the two spectral ranges is calculated (FIG. 3). The calculated difference determines the value of the refractive error component by the expressions:

$$\text{Δx}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{x}\left({\text{λ}}_{\text{one}}\right)-\text{x}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

$$\text{Δy}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{y}\left({\text{λ}}_{\text{one}}\right)-\text{y}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

where n (λ), n (λ ₁ ), n (λ ₂ ) are the refractive indices of the air path at the measurement wavelength and in the selected spectral ranges, respectively, (x (λ ₁ ), y (λ ₁ )), (x ( λ ₂ ), y (λ ₂ )) are the coordinates of the center of the irradiation distribution in the image of the reference mark 1 in the selected spectral ranges, M is the coefficient of conversion of coordinates from the image space to the space of objects.

Since for the calculation of the refractive component of the error it is necessary that the radiation of the reference mark 1 is visible in different spectral ranges, then at least one emitter of one reference mark 1 is made in the form of a white emitter.

The found value of the refractive error component is subtracted from the previously obtained coordinate values of the spatial position of the control marks 1 in the instrument coordinate system. After that, at least two common marks 1 are found between the measured control marks and the reference marks. The position of the common marks 1 determines the position of the instrument coordinate system in the external system, and the spatial position of the object is determined by the coordinates of the control marks 1, recounted from the instrument coordinate system to the external coordinate system. In this case, if the reference marks are fixed on stable structural elements of the controlled object that are not subject to deformation, and the remaining control marks are at critical points of the structure, it is possible to continuously measure the degree of deformation of the object, calculating the difference between the nominal and current position of the control marks, or controlling the increase in the difference between the reference and other marks in time. If the value of the difference exceeds the specified value, a warning is issued about the danger of a man-made disaster. The current position of the control marks is monitored in real time, which allows you to quickly respond to the threat of a disaster.

The device may contain several photodetectors 2 connected to a common processing unit 6, and several photodetectors 4 with optical filters 5 deposited on them within the same photodetector device 2. The presence of several photodetectors 4 allows the possibility of parallel image processing, i.e. carry out distributed calculations, as well as expand the effective field of view of each of the photodetector devices 2. The presence of several photodetector devices 2 allows you to work in a distributed field of view, due to which comprehensive measurements of sufficiently extended objects can be carried out. The photodetector devices 2 should be positioned in such a way that their total field of view covers all control marks 1, while at least two reference marks must be in the field of view of each photodetector device 2 to unambiguously “dock” the coordinate systems of all photodetector devices 2.

When using several photodetector devices 2 for measurements, each of them additionally contains a preprocessing unit, the first input of which is connected to the photodetector 4, the second input - with the second output of the processing unit 6, and the output - with the first input of the processing unit 6

It should be noted that the inventive device does not require sequentially measuring the position of the control marks 1. Here, the positions of all the control marks 1 are simultaneously fixed without moving the photodetector 2, which eliminates the measurement error associated with mechanical movements of the device, thereby increasing the accuracy of its operation.

Concrete example

A white semiconductor emitting diode (PID) is used as emitters in the reference reference marks 1: GNL-5013RGBW-C (C.C.) The emitters of the remaining reference marks 1 are made in the form of infrared PIDs operating at a wavelength of 880 nm. Each control mark 1 contains two PIDs mounted on a flat holder having the necessary fastenings to hold it on the controlled object. The tag control unit 7 is made by a single board with a microcontroller located on it and several tags 7 control channels, each of which consists of an inverter and an amplifier that perform pulse width modulation. The number of channels corresponds to the total number of PIDs.

In this case, the coordinate of the center of the irradiation distribution in the image of the mark 1 in the selected spectral range is the coordinate of the center of the segment connecting the energy centers of the images of the emitters of the control mark 1 according to the expressions:

, $$\text{y}\left(\text{λ}\right)=\frac{{\text{y}}_{\text{k2}}\left(\text{λ}\right)-{\text{y}}_{\text{k1}}\left(\text{λ}\right)}{\text{2}}$$

, $$\text{x}\left(\text{λ}\right)=\frac{{\text{x}}_{\text{k2}}\left(\text{λ}\right)-{\text{x}}_{\text{k1}}\left(\text{λ}\right)}{\text{2}}$$

, $$\text{y}\left(\text{λ}\right)=\frac{{\text{y}}_{\text{k2}}\left(\text{λ}\right)-{\text{y}}_{\text{k1}}\left(\text{λ}\right)}{\text{2}}$$

,

where (x _k1 (λ), y _k1 (λ)), (x _k2 (λ), y _k2 (λ)) are the coordinates of the energy centers of the images of the first and second emitter of check mark 1, respectively.

It should be noted that in the case of using a bidioid check mark 1 in the expressions:

, $$\text{Δy}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{1}\right)\left(\text{y}\left({\text{λ}}_{\text{1}}\right)-\text{y}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{1}}\right)\right)}\cdot \text{M}$$

$$\text{Δx}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{x}\left({\text{λ}}_{\text{one}}\right)-\text{x}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}$$

, $$\text{Δy}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{y}\left({\text{λ}}_{\text{one}}\right)-\text{y}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}$$

the scale factor M is calculated by the expression:

, $$\text{M}=\frac{\text{B}}{\sqrt{{\left({\text{x}}_{\text{one}}-{\text{x}}_{\text{2}}\right)}^{\text{2}}+{\left({\text{y}}_{\text{one}}-{\text{y}}_{\text{2}}\right)}^{\text{2}}}}$$

,

where B is the length of the base segment in the space of objects, measured a priori with great accuracy.

This shows that in this case, the scale factor is calculated automatically without including additional range-finding channels in the device.

Each photodetector 2 is made as a single unit in the form of a video camera, the optical system 3 of which is a lens with a focal length of 50 mm and an angular field of 29 °, the photodetector 4 is made in the form of a color CCD matrix of 1 / 2.5 inch format with a pixel size of 2, 2 μm × 2.2 μm with 2592 (H) × l944 (V) the number of active elements, and the preprocessing unit is a board with a microcontroller. The photosensitivity of the matrix is ensured by applying a Bayer filter to the photosensitive surface. The inter-frame difference algorithm is used in the red spectral channel, and the blue channel is used as the second spectral channel for measuring the refractive error component.

The processing unit 6 is made as a single unit with the label control unit 7 in the form of an electronic computer, while the control labels 1 are controlled via a radio channel, and the communication between the preprocessing unit and the processing unit 6 is via an Ethernet interface.

Thus, the claimed combination of features provides an increase in the accuracy of measuring the spatial position of the object.

Claims (3)

1. The method of measuring the spatial position of the object, which consists in the fact that in the controlled points of the object control marks are fixed, the radiation from which forms the distribution of irradiation in the image plane of the photodetector, fixing the distribution in one of the spectral ranges, an image is obtained by which the coordinates of the spatial positions of control marks in the instrument coordinate system (UCS), determining among the coordinates of control marks the coordinates of those points which are known in the external coordinate system, determine the position of the UCS relative to the external system, and the spatial position of the object is determined by the coordinates of the reference marks recalculated from the UCS to an external coordinate system, characterized in that they additionally fix the distribution of irradiation in the spectral range other than the first, comparing the coordinates the centers of irradiation distributions in each of the two spectral ranges for at least one label, determine the value of the refractive error:
$$\text{Δx}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{x}\left({\text{λ}}_{\text{one}}\right)-\text{x}\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

$$\text{Δy}\left(\text{λ}\right)=-\frac{\left(\text{n}\left(\text{λ}\right)-\text{one}\right)\left(\text{y}\left({\text{λ}}_{\text{one}}\right)-y\left({\text{λ}}_{\text{2}}\right)\right)}{\left(\text{n}\left({\text{λ}}_{\text{2}}\right)-\text{n}\left({\text{λ}}_{\text{one}}\right)\right)}\cdot \text{M}\text{,}$$

where n (λ), n (λ ₁ ), n (λ ₂ ) are the refractive indices of the air path at the measurement wavelength and in the selected spectral ranges, respectively;
(x (λ ₁ ), y (λ ₁ )), (x (λ ₂ ), y (λ ₂ )) are the coordinates of the center of the irradiation distribution in the label image in the selected spectral ranges;
M is the coefficient of conversion of coordinates from the space of images into the space of objects;
from the obtained coordinate values of the spatial position of the control marks in the instrument coordinate system, the value of the refractive error is subtracted. 2. The method according to claim 1, characterized in that it further fixes the distribution of background irradiation that does not contain irradiation from the control marks, comparing which with the distribution of irradiation obtained earlier in the same spectral range, identify different areas that are taken for the image of the marks over which determine the coordinates of the spatial position of the control marks in the UCS. 3. A device for measuring the spatial position of an object, including at least one reference mark made in the form of at least one point emitter placed on a controlled object, a photodetector optically coupled to a control mark, containing an optical system in which the photodetector is located in the focal plane, output which is connected to the input of the processing unit, and the label control unit, the input of which is connected to the first output of the processing unit, characterized in that at least one point The emitter of one control mark is made in the form of a white emitter, and the photodetector contains at least one photodetector, made in the form of a matrix detector of optical radiation, on each spatial element of which a filter of one of at least two different spectral ranges is applied.

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