CN103389121A - Angle detection device and method based on machine vision - Google Patents

Abstract

The invention discloses an angle detection device based on machine vision. The angle detection device comprises a casing and a rotary table arranged inside the casing, wherein a rotating shaft is arranged in the center of the rotary table; at least two identifications with same shapes but different sizes are arranged on the rotary table; the at least two identifications are overlapped in centers and are circles, parallelograms, regular triangles or polygons with sides of positive even numbers; at least one encoding strip identification is arranged between the identifications; center lines of encoding strip identifications penetrate through the center; codes corresponding to every two encoding strip identifications are different; and the device further comprises an image acquisition device used for acquiring an image of the rotary table and a lighting source. The invention further provides an angle detection method based on the machine vision at the same time. The angle detection device is simple in structure, high in pollution resistance and higher in impact resistance of the rotary table. According to the angle detection method, detection errors caused by pollutants can be identified and removed through an image processing technology, and the detection accuracy is high.

Description

Angle detection device and method based on machine vision

Technical field

The present invention relates to the encoder techniques field, particularly a kind of angle detection device based on machine vision and method.

Background technology

Rotary encoder is the device of measuring rotating speed, converts the mechanical quantity such as the angular displacement of output shaft, angular velocity to corresponding electric pulse and with digital output.Rotary encoder can be divided into optical grating principle scrambler and magnetic magnetic grid principle scrambler.Grating principle rotary encoder comprises the Yi Ge center and is provided with the photoelectric code disk of rotating shaft, logical, the dark groove of annular is arranged on photoelectric code disk, when a pitch of photoelectric code disk rotation, light activated element obtains having A phase, the B phase pulse signal of 90 degree phase differential under the light-emitting component irradiation, A phase, B phase pulse signal are after frequency turns voltage transformation, obtain and the proportional voltage signal of rotating shaft rotating speed, can record velocity amplitude and displacement.The rotary encoder measuring accuracy of grating principle is high, but that shortcoming is contamination resistance is poor.The magnetic grid rotary encoder utilizes the magnetic action of magnetic grid and magnetic head,, with the circle-shaped magnetic that replacing, produces the S utmost point and the N utmost point on this magnetic rubber ring, adopts mistor or hall effect sensor as sensitive element, by magnetic force, forms spike train, produces signal.The rotary encoder of magnetic grid principle has stronger antipollution, impact resistance, but that shortcoming is measuring accuracy is not high.

Summary of the invention

The object of the invention is to overcome in prior art that existing raster rotary coder contamination resistance is poor, the not high deficiency of magnetic grid rotary encoder measuring accuracy, a kind of angle detection device based on machine vision is provided, a kind of angle detecting method based on machine vision is provided simultaneously, improves contamination resistance, impact resistance when realizing accurately detection.

, in order to realize the foregoing invention purpose, the invention provides following technical scheme:

A kind of angle detection device based on machine vision, comprise housing and the rotating disk that is arranged at enclosure interior, the center of described rotating disk is provided with rotating shaft, rotating disk is provided with identical but at least two signs varying in size of shape, and described at least two are designated circle, parallelogram, equilateral triangle or the positive even numbers limit shape that center coincides; Be provided with at least one encoding strip mark between sign, and every encoding strip target center line is crossed center, every corresponding coding of encoding strip mark, and coding difference corresponding to every two encoding strip marks; Also comprise that described lighting source and digital image acquisition device are fixed by housing for image collecting device and the lighting source of picked-up rotating disk image.

So-called machine vision, replace human eye to do with machine exactly and measure and judgement.Vision Builder for Automated Inspection refers to that by machine vision product (be image-pickup device, two kinds of minute CMOS and CCD) will be ingested target and convert picture signal to, send special-purpose image processing system to,, according to information such as pixel distribution and brightness, colors, be transformed into digitized signal; Picture system carries out various computings to these signals and carrys out the feature of extracting objects, and then according to the result of differentiating, controls on-the-spot device action.

Further, describedly be designated two, be respectively the first sign and second and identify.Preferably, described the first sign and the second sign are circle.

Apply above-mentioned angle detection device based on machine vision and carry out the method that angle detects, comprise the following steps:

(1) uncalibrated image harvester inner parameter matrix K;

(2) utilize image collecting device picked-up rotating disk image,, from the identification image that is partitioned at least two signs of rotating disk image, ask at least two identification image equations, and according to the image coordinate at least two identification image Solving Equations label taking Shi De centers;

(3) at moment t1, the picked-up encoding strip picture of marking on a map, resolve the first encoding strip target coding, and extract first encoding strip target the first boundary image equation;

(4) at moment t2, the picked-up encoding strip picture of marking on a map, resolve the second encoding strip target coding, and extract the second encoding strip target the second boundary image equation;

(5) ask for the line equation that goes out on sign plane, place, and ask for the vanishing point coordinate of the second boundary place rectilinear direction on the vanishing point coordinate of the first place, border rectilinear direction on the line that goes out and the line that goes out;

(6) according to two intersecting point coordinates and parameter matrix K, ask for respectively t1 the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector constantly, according to the first encoding strip mark and the second encoding strip target unit direction vector, ask for the angle that t1 to t2 rotated in the time period.

Further, described in step (2), at least two signs are circle.

Further, utilize image collecting device picked-up rotating disk image described in step (2), from the identification image that is partitioned at least two signs of rotating disk image, the method for asking at least two identification image equations is:

If g1 be a circular curve through the image that image collecting device collects, extract the border of this circular curve, and choose arbitrarily at least 5 points on border, seek out at least 5 corresponding image coordinate of point, be expressed as respectively (u _iv _i) i=1,2,3..., the equation general formula of g1 can be described as: $g(u,v)={\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]}^T\&CenterDot;M\&CenterDot;\left[\begin{array}{c}\mathrm{<figure-callout\; id="1"\; label="u\; v"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">u</figure-callout>}& \\ v\\ 1\end{array}\right]=0,$ $M=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right],$ Get A=1, with at least 5 corresponding image coordinate (u of point _iv _i) in the substitution following formula, have ${\left[\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right]}^T\&CenterDot;\left[\begin{array}{ccc}1& 0.5c& 0.5d\\ 0.5c& b& 0.5e\\ 0.5d& 0.5e& f\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_{\mathrm{<figure-callout\; id="1"\; label="i\; v\; i"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">i</figure-callout>}}& \\ v_i{}_{}\\ 1\end{array}\right]=0,$ Wherein, b=B/A, c=C/A, d=D/A, e=E/A, f=F/A; Solve b, c, d, e, f, the identification image equation is: G _i(u, v)=A _iu ²+ B _iv ²+ C _iUv+D _iu+E _iv+F _i=0 wherein, A _i=1.

Further, the method for the image coordinate at least two identification image Solving Equations label taking Shi De centers of basis described in step (2) is:

If the image coordinate at center is (u ₀v ₀), the image coordinate at circular image equation Yu Qi center meets relation $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right],\end{array}$ Wherein, a ', b ', c ' be respectively circle the coefficient of the line equation that goes out in the plane; According to $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\begin{array}{c}\left[\begin{array}{ccc}{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1\\ {0.5C}_1& {\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">E</figure-callout>}}_1\\ {0.5\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1& {0.5E}_1& F_1\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]=\left[\begin{array}{ccc}{A}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2\\ {0.5C}_2& {\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">B</figure-callout>}}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">E</figure-callout>}}_2\\ {0.5\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2& {0.5E}_2& F_2\end{array}\right]\&CenterDot;\end{array}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]$ Can draw the image coordinate (u at center ₀v ₀); Wherein, A ₁, B ₁, C ₁, D ₁, E ₁, F ₁For the coefficient of one of them identification image equation, A ₂, B ₂, C ₂, D ₂, E ₂, F ₂For another knows the coefficient of image equation.

Further, the method for the line equation that goes out of asking for sign plane, place of described step (5) is:

By center image coordinate (u ₀v ₀), at least two identification image equations, according to equation $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]$ Solve coefficient a ', the b ' of the line equation that goes out, the value of c ', the line equation that goes out that identifies the plane, place is: a ' u+b ' v+c '=0.

Further,, according to two intersecting point coordinates and parameter matrix K, ask for respectively t1 the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector constantly described in step (6), its method is:

If the unit direction vector of place, encoding strip mark border straight line is

It can be by the vanishing point coordinate (u that this side up _j, v _j) substitution ${\mathrm{\&rho;}}_j\&CenterDot;\begin{array}{}\end{array}\left[\begin{array}{c}{v}_{\mathrm{xj}}\\ v_{\mathrm{yj}}\\ v_{\mathrm{zj}}\end{array}\right]=K^{-1}\left[\begin{array}{c}{u}_{\mathrm{<figure-callout\; id="1"\; label="j\; v\; j"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">j</figure-callout>}}& \\ v_j{}_{}\\ 1\end{array}\right]$ Draw, wherein, ρ _iIt is any non-zero constant; Use vectorial method for normalizing, and according to encoding strip, be marked on the binary encoding bar upper appearance position of picture of marking on a map, can determine the coordinate of unit direction vector; Obtain respectively thus the first encoding strip mark and the second encoding strip target unit direction vector.

Further, ask for according to the first encoding strip mark and the second encoding strip target unit direction vector the angle that t1 to t2 rotated in the time period described in step (6), its method is: α=β ± θ, wherein, α is the angle that t1 to t2 rotated in the time period, β is the angle between the t1 moment the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector, and θ is the angle between the first encoding strip mark and the second encoding strip mark.

Compared with prior art, beneficial effect of the present invention:

The present invention is based on the angle detection device of machine vision, can realize increment type or the absolute type measurement of rotational angle, velocity of rotation, rotation acceleration.Due to contactless between image collecting device and rotating disk, angle detection device contamination resistance of the present invention is strong.Because rotating disk does not need to possess transmittancy, so rotating disk can adopt the stiff materials such as alloy to make, and impact resistance is stronger.

The angle detection device that the present invention is based on machine vision is simple in structure, and the scale of rotating disk (encoding strip mark) is drawn simpler than the making of optical grating, and cost is lower.

The present invention is based on the angle detecting method of machine vision, the image in using on rotating disk is in a big way originated as measurement data, coordinates image processing techniques, has reduced the impact that the image local distortion produces the whole detection precision; And if pollutant differs greatly with the rotating disk sign on visual characteristic, can identify rejecting by image processing techniques, can not exert an influence to final measurement, the problem that the accuracy of detection of having avoided pollutant to cause is lower, improve accuracy of detection, measure by experiment relative error lower than 0.5%.

Angle detecting method of the present invention uses flexibly, realizes that the device of angle detection can independently be made, and also can draw the encoding strip mark on existing equipment, then the combining image harvester can realize that angle detects.

Description of drawings:

Fig. 1 is the angle detection device structural representation that the present invention is based on machine vision.

Fig. 2 is encoding strip target structural representation.

Fig. 3 is the process flow diagram that the present invention is based on the angle detecting method of machine vision.

Mark in figure: 1-rotating shaft, 2-encoding strip mark, 3-cylindrical sign, 4-inner circle sign, 5-image collecting device, 6-rotating disk, 7-housing, 8-lighting source, 201-bits of coded.

Embodiment

The present invention is described in further detail below in conjunction with test example and embodiment.But this should be interpreted as that the scope of the above-mentioned theme of the present invention only limits to following embodiment, all technology that realizes based on content of the present invention all belong to scope of the present invention.

With reference to figure 1, angle detection device based on machine vision provided by the invention, comprise that a center is provided with the rotating disk 6 of rotating shaft 1, rotating disk 6 is provided with concentric but cylindrical sign 3 and the inner circle sign 4 of different-diameter, the diameter of cylindrical sign 3 is greater than inner circle sign 4, be provided with at least one encoding strip mark 2 between cylindrical sign 3 and inner circle sign 4, and the center line of every encoding strip mark 2 crosses the center of circle, namely the center of circle of rotating disk 6 is on the center line of encoding strip mark 2.When encoding strip mark 2 was two or more, the distance (being angle) between every adjacent two encoding strip marks 2 can arrange arbitrarily, but the angle between adjacent two encoding strip marks 2 is known.With reference to figure 2, encoding strip mark 2 is provided with several bits of coded 201, and bits of coded represents different encoded radios after being colored as different colors.The bits of coded number that all encoding strips on same rotating disk are put on is identical, and coded system is identical, namely according to equidirectional, carries out coding/decoding (, namely according to equidirectional, read successively encoding strip and put on the encoded radio of each bits of coded), obtains coding.If it is painted to adopt m kind color to carry out bits of coded, an encoding strip is put on n bits of coded is set, and can obtain m so ⁿThe encoding strip mark of bar different coding, although the encoding strip mark quantity that arranges on rotating disk can arrange arbitrarily, every encoding strip target coding on same rotating disk must be different.Because the encoding strip mark on rotating disk need not to arrange too much (at least one can realize),, for the ease of coding/decoding, preferably adopt two kinds of colors presentation code value 1 and encoded radio 0 respectively, every encoding strip mark arranges 4-6 bits of coded.In the present embodiment, adopt black to represent encoded radio 0, white presentation code value 1, every the encoding strip mark arranges 6 bits of coded, as shown in Figure 2, this encoding strip target is encoded to 011011(according to reading successively from top to bottom, namely from closing on center of circle end to away from center of circle end, reading successively).Encoding strip is put on several bits of coded is set, and bits of coded is colored as different colours with expression different coding value, such purpose is to make the corresponding coding of an encoding strip mark, certain, can take other embodiments (for example, directly at encoding strip, putting on label coding) to realize the corresponding coding of an encoding strip mark.Rotating disk 6 is arranged at the inside of housing 7, and an end of rotating shaft 1 passes housing 7, so that with engine, be connected.The angle detection device that the present invention is based on machine vision also comprises lighting source 8 and the digital image acquisition device 5 that is arranged at enclosure interior, lighting source 8 and digital image acquisition device 5 are fixing by housing 7, the installation site of lighting source 8 and digital image acquisition device 5 is not particularly limited, but must meet and can obtain image clearly, and comprise at least the part or all of of inner circle sign 4, cylindrical sign 3 in the image that obtains, and at least one complete encoding strip mark 2.Dispose data processing unit in digital image acquisition device 5, digital image acquisition device 5 can directly adopt digital camera.

Need to prove, the shape of encoding strip mark 2 can, for triangle, the arbitrary shape such as trapezoidal, be not limited only to the rectangle shown in Fig. 2.The cylindrical sign 3 and the inner circle sign 4 that arrange on rotating disk 6 are not limited only to two, a plurality of concentric circles signs can be set, but be at least two; Cylindrical sign 3 and inner circle sign 4(concentric circles sign) also be not limited only to circle, cylindrical sign 3 and inner circle sign 4 also can be parallelogram, equilateral triangle and any positive even numbers limit shape, but the center of cylindrical sign 3 and inner circle sign 4 coincides, and size is unequal.

With reference to figure 3, utilize above-mentioned angle detection device based on machine vision to carry out the method that angle detects, comprise the following steps:

(1) demarcate digital camera (being digital image acquisition device) inner parameter matrix K, and be kept in its supporting data processing unit.The scaling method of digital camera inner parameter matrix K belongs to prior art, does not do too much elaboration herein., for the demarcation of digital camera inner parameter matrix K, again digital camera is installed in the housing of angle detection device after can first to K, demarcating; Also can first digital camera be installed in the housing of angle detection device, and then adopt the self calibration algorithm automatically to complete the demarcation of parameter matrix K, but need to increase corresponding calibration sign.

(2) utilize digital camera picked-up rotating disk image (comprising inner circle identification image and cylindrical identification image in the rotating disk image), be partitioned into inner circle identification image and cylindrical identification image from the rotating disk image, and ask for inner circle identification image equation and cylindrical identification image equation, then according to inner circle identification image equation and cylindrical identification image equation, ask for its center of circle image coordinate.

(2-1) ask for inner circle identification image equation and cylindrical identification image equation.

If g1 be a circular curve through the image that digital camera collects, extract the border of this circular curve, and choose arbitrarily at least 5 points on border, seek out at least 5 corresponding image coordinate of point, be expressed as respectively (u _iv _i) 1,2,3..., the equation general formula of g1 can be described by following equation:

$g(u,v)={\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]}^T\&CenterDot;M\&CenterDot;\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]=0,M=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]$

Because the element in Metzler matrix is not 0 entirely, therefore with Metzler matrix divided by A, Metzler matrix can be expressed as:

$M=\left[\begin{array}{ccc}1& 0.5c& 0.5d\\ 0.5c& b& 0.5e\\ 0.5d& 0.5e& f\end{array}\right]$

Wherein, b=B/A, c=C/A, d=D/A, e=E/A, f=F/A.By following formula as seen, the independent variable in Metzler matrix becomes 5 (that is, b, c, d, e, f), therefore the coordinate (u of at least 5 points of known g1 _iv _i) substitution $g(u,v)={\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]}^T\&CenterDot;M\&CenterDot;\left[\begin{array}{c}\mathrm{<figure-callout\; id="1"\; label="u\; v"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">u</figure-callout>}& \\ v\\ 1\end{array}\right]=0,$ Can obtain at least 5 prescription journeys:

${\left[\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right]}^T\&CenterDot;\left[\begin{array}{ccc}1& 0.5c& 0.5d\\ 0.5c& b& 0.5e\\ 0.5d& 0.5e& f\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right]=0$

After solving 5 variablees (b, c, d, e, f) by following formula, can unique definite Metzler matrix.If equation quantity, more than 5, utilizes least square method to ask for the optimum solution of Metzler matrix.

According to the method described above, solve successively concentric circles identification image equation (in the present embodiment, being namely to obtain cylindrical identification image equation and inner circle identification image equation), be designated as:

G _i(u,v)=A _iu ²+B _iv ²+C _iuv+D _iu+E _iv+F _i=0

Wherein, A _i=1.

(2-2) calculate center of circle image coordinate.

If the image coordinate in the center of circle is (u ₀v ₀), the image coordinate in circular image equation and its center of circle meets following relation:

$\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]\end{array}$

Wherein, a ', b ', c ' be respectively circle the coefficient of the line equation that goes out in the plane., because front has solved cylindrical identification image equation and inner circle identification image equation, therefore can be able to lower equation:

$\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\begin{array}{c}\left[\begin{array}{ccc}{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">A</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1\\ {0.5C}_1& {\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">B</figure-callout>}}_1& {0.5\mathrm{<figure-callout\; id="1"\; label="E"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">E</figure-callout>}}_1\\ {0.5\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_1& {0.5E}_1& F_1\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]=\left[\begin{array}{ccc}{A}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">C</figure-callout>}}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2\\ {0.5C}_2& {\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">B</figure-callout>}}_2& {0.5\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">E</figure-callout>}}_2\\ {0.5\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">D</figure-callout>}}_2& {0.5E}_2& F_2\end{array}\right]\&CenterDot;\end{array}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]$

Can uniquely solve central coordinate of circle (u thus ₀v ₀).When being provided with more than the concentric circles of two sign on rotating disk, after solving all concentric circles identification image equations, can be solved by least square method the optimum solution of central coordinate of circle.

(3) by center of circle image coordinate, cylindrical sign circular image equation or inner circle sign circular image equation, according to equation $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]\end{array}$ (line that goes out is defined as: in projective mapping to solve the line that goes out, on plane, all infinity points are positioned on straight line, this straight line is " line goes out " or " blanking line ", English is: vanish line) coefficient a ', the b ' of equation, the value of c ', then ask for the equation of the line L that goes out of plane of rotor disc (being the plane at cylindrical sign and inner circle sign place), the line equation that goes out is: a ' u+b ' v+c '=0, and be saved in the supporting data processing unit of digital camera.

Need to prove,, if wish is changed digital camera and/or rotating disk in measuring process, need to re-execute step (1) to (3), again ask for center of circle image coordinate, line equation etc. goes out.

(4) when time t1, digital camera gathers rotating disk image (comprising at least one complete mark of encoding strip clearly in the rotating disk image), identifies, is partitioned into clear, the most complete encoding strip picture of marking on a map.Mark on a map the implication of picture of the encoding strip of complete display is herein, adopts the out of focus decision algorithm to calculate the sharpness of all rotating disk images of obtaining, the encoding strip of choosing the sharpness maximum picture of marking on a map.Due to after digital camera installs, its blur-free imaging district determines thereupon, and therefore, the encoding strip of the complete display picture of marking on a map preferentially obtains from blur-free imaging district.

(5) decoding and coding bar mark C1, namely the encoded radio of upper each bits of coded of discrimination encoding strip mark C1 is 1 or is 0, forms coding d1, is saved in data processing unit.

(6) adopt Algorithm of fitting a straight line, the image equation on match partition encoding bar mark C1 left (or right) border, and solve the image equation on border, this left side (or right) and the intersection point P1 (u of the line L that goes out ₁v ₁).Need to prove intersection point P1 (u herein ₁v ₁) actual being the vanishing point on encoding strip mark C1 on the line that goes out left (or right) place, border rectilinear direction, in actual treatment, obtaining of vanishing point coordinate is exactly the intersecting point coordinate of asking for absorbing boundary equation and the line that goes out.

(7) at time t2, repeating step (4) and (5), extract the coding d2 of encoding strip mark C2, and obtain the image equation on left encoding strip mark C2 left (or right) border and the intersection point P2 (u of the line L that goes out ₂v ₂).Intersection point P2 (u herein ₂v ₂) actual be the vanishing point on encoding strip mark C2 on the line that goes out left (or right) place, border rectilinear direction.

Need to prove, if rotating disk is that the angle between t1 encoding strip mark C1 constantly and the t2 encoding strip mark C2 position in the moment and the integral multiple sum of 360 °, so just can't detect the velocity of rotation of rotating disk in the angle that t1 to t2 rotated in the time.Therefore, can pass through the test of many times verification mode, dwindle gradually the mistiming between t1 and t2, finally obtain two different coding bar target images taking in a rotation period, that is, rotating disk is the encoding strip mark C1 in the t1 moment and the angle between t2 encoding strip mark C2 position constantly in the angle that t1 to t2 rotated in the time.If at encoding strip mark C1 and the C2 that t1 and t2 photograph constantly, be one and same coding bar mark, encoding strip mark C1(or C2 so) respectively t1 constantly and t2 constantly the angle between position be the angle that rotating disk rotates in the time at t1 to t2.In order to measure more accurately the rotational angle of the rotating disk with higher rotation speed, constantly get the image of the encoding strip mark C2 different from C1 at t2, namely the encoding strip mark on rotating disk should be set at least two.

(8) ask for t1 moment encoding strip mark C1 and the t2 angle between encoding strip mark C2 constantly, and according to this angle, ask for velocity of rotation.This step comprises:

(8-1), by intersection point P1, P2, camera inner parameter K and twice encoding strip target image information, solve encoding strip mark C1 and C2 point to respectively on t1, t2 time point direction vector.

If the unit direction vector of place, encoding strip mark border straight line is

It can be by the vanishing point coordinate (u that this side up _j, v _j) acquisition of substitution following formula:

${\mathrm{\&rho;}}_j\&CenterDot;\begin{array}{}\end{array}\left[\begin{array}{c}{v}_{\mathrm{xj}}\\ v_{\mathrm{yj}}\\ v_{\mathrm{zj}}\end{array}\right]=K^{-1}\left[\begin{array}{c}{u}_{\mathrm{<figure-callout\; id="1"\; label="j\; v\; j"\; filenames="HDA0000370001670000011.png"\; state="\{\{state\}\}">j</figure-callout>}}& \\ v_j{}_{}\\ 1\end{array}\right]$

Wherein, when the direction vector v1 of unit on border, a left side of asking for encoding strip mark C1 (or right), j=1, when the direction vector v2 of unit on border, a left side of asking for encoding strip mark C2 (or right), j=2, ρ _iBe any non-zero constant, use vectorial method for normalizing, two groups of feasible solutions that can the unit's of obtaining direction vector.And the corresponding relation of image-region and direction vector can be determined in case setting is completed in the position of digital camera, that is, can mark on a map as the appearance position on general image according to encoding strip, determines its true solution.Can obtain respectively thus the direction vector v1 of unit, the v2 on the border, a left side (or right) of encoding strip mark C1, C2, the direction vector v1 of unit, the v2 on border, the left side of encoding strip mark C1, C2 (or right) is encoding strip mark C1 and C2 point to respectively on t1, t2 time point direction vector, encoding strip mark C1 and C2 respectively can presentation code bar mark C1 and the C2 current location on t1, t2 time point respectively at the direction vector that points on t1, t2 time point, and namely the angle between v1, v2 is the angle between t1 encoding strip mark C1 constantly and the t2 encoding strip mark C2 in the moment.

(8-2) according to the angle between the t1 moment encoding strip mark C1 that asks for and t2 moment encoding strip mark C2, and fixing angle between encoding strip mark C1 and C2 on rotating disk, ask for the angle that rotating disk rotates in the time at t1 to t2: α=β ± θ, wherein, α is the angle that t1 to t2 rotated in the time period, β is the angle between the t1 moment the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector, and θ is the angle between the first encoding strip mark and the second encoding strip mark.

If definition rotates counterclockwise as positive dirction, and actual when rotating counterclockwise, so at t1 to t2 in the time, the angle of dial rotation is α=β+θ.

If definition rotates counterclockwise as positive dirction, actual when clockwise rotating, so at t1 to t2 in the time, the angle of dial rotation is α=β-θ.

Introduce time interval parameter, can obtain velocity of rotation, rotation acceleration parameter.

Disclosed all features in this instructions, or the step in disclosed all methods or process, except mutually exclusive feature and/or step, all can make up by any way.

Disclosed arbitrary feature in this instructions (comprising any accessory claim, summary and accompanying drawing), unless special narration all can be replaced by other equivalences or the alternative features with similar purpose.That is, unless special narration, each feature is an example in a series of equivalences or similar characteristics.

Claims (10)

1. angle detection device based on machine vision, it is characterized in that, comprise housing and the rotating disk that is arranged at enclosure interior, the center of described rotating disk is provided with rotating shaft, rotating disk is provided with identical but at least two signs varying in size of shape, and described at least two are designated circle, parallelogram, equilateral triangle or the positive even numbers limit shape that center coincides; Be provided with at least one encoding strip mark between sign, and every encoding strip target center line is crossed center, every corresponding coding of encoding strip mark, and coding difference corresponding to every two encoding strip marks; Also comprise that described lighting source and digital image acquisition device are fixed by housing for image collecting device and the lighting source of picked-up rotating disk image.

2. the angle detection device based on machine vision according to claim 1, is characterized in that, describedly is designated two, and the first sign and second identifies respectively.

3. the angle detection device based on machine vision according to claim 2, is characterized in that, described the first sign and the second sign are circle.

4. application rights requires 1 described angle detection device based on machine vision to carry out the method that angle detects, and it is characterized in that, comprises the following steps:

(1) uncalibrated image harvester inner parameter matrix K;

(2) utilize image collecting device picked-up rotating disk image,, from the identification image that is partitioned at least two signs of rotating disk image, ask at least two identification image equations, and according to the image coordinate at least two identification image Solving Equations label taking Shi De centers;

(3) at moment t1, the picked-up encoding strip picture of marking on a map, resolve the first encoding strip target coding, and extract first encoding strip target the first boundary image equation;

(4) at moment t2, the picked-up encoding strip picture of marking on a map, resolve the second encoding strip target coding, and extract the second encoding strip target the second boundary image equation;

(5) ask for the line equation that goes out on sign plane, place, and ask for the vanishing point coordinate of the second boundary place rectilinear direction on the vanishing point coordinate of the first place, border rectilinear direction on the line that goes out and the line that goes out;

(6) according to two intersecting point coordinates and parameter matrix K, ask for respectively t1 the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector constantly, according to the first encoding strip mark and the second encoding strip target unit direction vector, ask for the angle that t1 to t2 rotated in the time period.

5. method according to claim 4, is characterized in that, described in step (2), at least two signs are circle.

6. method according to claim 5, is characterized in that, utilizes image collecting device picked-up rotating disk image described in step (2), and from the identification image that is partitioned at least two signs of rotating disk image, the method for asking at least two identification image equations is:

If g1 be a circular curve through the image that image collecting device collects, extract the border of this circular curve, and choose arbitrarily at least 5 points on border, seek out at least 5 corresponding image coordinate of point, be expressed as respectively (u _iv _i) i=1,2,3 ..., the equation general formula of g1 can be described as: $g(u,v)={\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]}^T\&CenterDot;M\&CenterDot;\left[\begin{array}{c}u\\ v\\ 1\end{array}\right]=0,$ $M=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right],$ Get A=1, with at least 5 corresponding image coordinate (u of point _iv _i) in the substitution following formula, have ${\left[\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right]}^T\&CenterDot;\left[\begin{array}{ccc}1& 0.5c& 0.5d\\ 0.5c& b& 0.5e\\ 0.5d& 0.5e& f\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_i\\ v_i\\ 1\end{array}\right]=0,$ Wherein, b=B/A, c=C/A, d=D/A, e=E/A, f=F/A; Solve b, c, d, e, f, the identification image equation is: G _i(u, v)=A _iu ²+ B _iv ²+ C _iUv+D _iu+E _iv+F _i=0 wherein, A _i=1.

7. method according to claim 6, is characterized in that, the method for the image coordinate at least two identification image Solving Equations label taking Shi De centers of basis described in step (2) is:

If the image coordinate at center is (u ₀v ₀), the image coordinate at circular image equation Yu Qi center meets relation $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right],\end{array}$ Wherein, a ', b ', c ' be respectively circle the coefficient of the line equation that goes out in the plane; According to $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\begin{array}{c}\left[\begin{array}{ccc}{A}_1& {0.5C}_1& {0.5D}_1\\ {0.5C}_1& B_1& {0.5E}_1\\ {0.5D}_1& {0.5E}_1& F_1\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]=\left[\begin{array}{ccc}{A}_2& {0.5C}_2& {0.5D}_2\\ {0.5C}_2& B_2& {0.5E}_2\\ {0.5D}_2& {0.5E}_2& F_2\end{array}\right]\&CenterDot;\end{array}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]$ Can draw the image coordinate (u at center ₀v ₀); Wherein, A ₁, B ₁, C ₁, D ₁, E ₁, F ₁For the coefficient of one of them identification image equation, A ₂, B ₂, C ₂, D ₂, E ₂, F ₂For another knows the coefficient of image equation.

8. method according to claim 7, is characterized in that, the method for the line equation that goes out of asking for sign plane, place of described step (5) is:

By center image coordinate (u ₀v ₀), at least two identification image equations, according to equation $\left[\begin{array}{c}{a}^{\&prime;}\\ b^{\&prime;}\\ c^{\&prime;}\end{array}\right]=\left[\begin{array}{ccc}A& 0.5C& 0.5D\\ 0.5C& B& 0.5E\\ 0.5D& 0.5E& F\end{array}\right]\&CenterDot;\begin{array}{c}\left[\begin{array}{c}{u}_0\\ v_0\\ 1\end{array}\right]\end{array}$ Solve coefficient a ', the b ' of the line equation that goes out, the value of c ', the line equation that goes out that identifies the plane, place is: a ' u+b ' v+c '=0.

9. method according to claim 8, is characterized in that,, according to two intersecting point coordinates and parameter matrix K, asks for respectively t1 the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector constantly described in step (6), and its method is:

If the unit direction vector of place, encoding strip mark border straight line is

It can be by the vanishing point coordinate (u that this side up _j, v _j) substitution ${\mathrm{\&rho;}}_j\&CenterDot;\begin{array}{}\end{array}\left[\begin{array}{c}{v}_{\mathrm{xj}}\\ v_{\mathrm{yj}}\\ v_{\mathrm{zj}}\end{array}\right]=K^{-1}\left[\begin{array}{c}{u}_j\\ v_j\\ 1\end{array}\right]$ Draw, wherein, ρ _iIt is any non-zero constant; Use vectorial method for normalizing, and according to encoding strip, be marked on the binary encoding bar upper appearance position of picture of marking on a map, can determine the coordinate of unit direction vector; Obtain respectively thus the first encoding strip mark and the second encoding strip target unit direction vector.

10. method according to claim 9, it is characterized in that, ask for according to the first encoding strip mark and the second encoding strip target unit direction vector the angle that t1 to t2 rotated in the time period described in step (6), its method is: α=β ± θ, wherein, α is the angle that t1 to t2 rotated in the time period, and β is the angle between the t1 moment the first encoding strip mark and the t2 moment the second encoding strip target unit direction vector, and θ is the angle between the first encoding strip mark and the second encoding strip mark.

Images