Line-shaped laser vertical rotation type three-dimensional appearance measuring apparatus and method thereof

Mode of execution

In conjuction with the following further detailed description of and embodiment of the specific structure of the present invention, the content of the working principle.

A word of the invention laser vertically rotary three-dimensional topography measurement device of one embodiment, as shown in Figure 1, Figure 2, Figure 3, Figure 4 is shown, comprises a base 1, a camera 2, a word line laser 3, a motor 5, driving mechanism 30, rotary shaft 6, the connecting piece 4, angle measuring element 7, conversion circuit, a motor drive circuit and a controller; the motor 5 is fixedly connected with the base 1 on, the rotating shaft 6 is sleeved on the base 1 in, the motor 5 through the output shaft of the transmission mechanism 30 and the rotating shaft 6 is connected, the camera 2, a word line laser 3 and the rotating shaft 6 are connected by the connecting piece 4 is fixedly connected with the; angle measuring element 7 of the motor 5 output shaft, transmission mechanism 30 or the rotating shaft of the output shaft of the 6 upper; said a word line laser 3 the plane of the laser emitted by the laser plane S referred to, the rotating shaft 6 the centerline L₁ on S in the laser plane; said camera 2 through the Image acquisition card is connected with the controller, the motor 5 through the motor drive circuit is connected with the controller, the angle measuring element 7 is connected with a controller through a switching circuit; the rotating shaft 6 the centerline L₁ with the camera 2 of the optical center of the lens O_c formed with H the observation plane of the included angle between the laser plane for β S 80-100 ° ; the rotating shaft 6 the centerline L₁ with the camera 2 of the included angle between the optical axis of the lens the Lc between 40-50 ° ; the a word line laser onto the surface of the object measured by the laser stripe in the observation range of the camera.

A word of the invention laser vertically rotary three-dimensional topography measurement device of the controller and the motor, such as a video camera and the angle of the connection relationship of the measuring element a schematic diagram as shown in Figure 8.

A word of the invention laser vertically rotary three-dimensional shape measuring device, characterized in that the angle measuring component adopts the angle detector, the angular displacement sensor, a potentiometer or encoder.

In this embodiment, the angle of the encoder of the measuring element.

A word of the invention laser vertically rotary three-dimensional shape measuring device, characterized in that said controller uses the computer, single-chip microcomputer, DSP or microcontroller.

In this embodiment, the controller of the industrial control computer.

A word of the invention laser vertically rotary three-dimensional shape measuring device, characterized in that said transmission mechanism is a gear transmission mechanism, gear rack drive mechanism, with wheel transmission mechanism, chain wheel transmission mechanism, tendon rope transmission mechanism, lead screw and nut transmission mechanism, the connecting rod driving mechanism, the worm and gear transmission mechanism, the cam drive mechanism or a ratchet wheel drive mechanism of one kind or several kinds of combined.

In this embodiment, the driving mechanism 30 of the gear transmission mechanism, the driving mechanism 30 includes the reducer 9, 1st gear 10 and 2nd gear 11, the motor 5 and the output shaft of the speed reducer 9 is connected with the input shaft, a speed reducer of the 1st gear 10 is fixedly connected, 1st gear 10 and the 2nd gear 11 is meshed with each other to form a gear drive relations, 2nd gear 11 is set on the rotating shaft 6 on.

A word of the invention laser vertically rotary three-dimensional shape measuring device, characterized in that the camera using CCD camera or CMOS camera.

In this embodiment, the camera 2 of the CCD camera.

In this embodiment, the rotating shaft 6 the centerline L₁ with the camera 2 of the optical center of the lens of the observation plane H forming Oc with the included angle between the laser plane for β S 80-100 ° ; the rotating shaft 6 the centerline L₁ with the camera 2 of the included angle between the optical axis of the lens in φ Lc between 40-50 °.

In this embodiment, the word line laser 3 projected onto the surface of the object measured by the laser stripe distance camera 2 of the optical center of the lens O_c more than 6 times the focal length.

A word of the invention laser vertically rotary three-dimensional topography measurement device of the embodiment of another kind, as shown in Figure 7, angle measuring element of a potentiometer. Figure 8 is a schematic diagram of connection relation of Figure 7 shown in the controller and the motor of the embodiment of, the camera and the angle of the measuring element, in this embodiment, the controller adopts a computer, angle measuring element of a potentiometer, conversion circuit A/D conversion circuit with the data acquisition card.

use chart 1 or Figure 7 shown in the method for measuring the embodiment, as shown in Figure 9, comprises the following steps:

(A) establishment of the Image coordinate system {P}, {A} coordinate system as the target, the camera coordinate system {C}, a base coordinate system and laser coordinate system {B} {L};

(B) through the calibration experiment, to obtain the Image coordinate system {P}, {A} coordinate system as the target, the camera coordinate system {C}, a base coordinate system and laser coordinate system {B} {L} the coordinate transformation relations between;

(C) said one word line laser 3 the laser emitted by the laser plane as the plane of the H, through the calibration experiment to obtain the laser plane H {L} in the laser coordinate system of the plane equation, coordinate conversion of the laser plane H by the camera coordinate system {C} equation of the plane of the;

(D) a motor 5 driving the rotating shaft 6 is rotated to the position of a certain angle (such as angle position θ);

(E) through the angle measuring element 7 of the angle values measured; a word line laser 3 emits a word linear laser light is formed on the surface of the measured object to a stripe, camera 2 of the stripe containing the shot Image on the object surface;

(F) Image processing Image stripe point j on the Image coordinate system of the coordinate of the {P} (u_j, v_j); by coordinate conversion target point j of the coordinate system the coordinates of {A} (^A x_j,^A y_j); coordinate conversion point j with the counterpart obtained i determined point imaging linear L_i in the camera coordinate system {C} the straight-line equation of the, combination (c) step of the laser plane equation, imaging the straight line and by the intersection of the laser plane i the camera coordinate system the coordinates of {C} (^C X_i,^C Y_i,^C Z_i), i point coordinate conversion obtained in the laser coordinate system the coordinates of {L} under (^L X_i,^L Y_i,^L Z_i), i coordinate conversion by the base point of the coordinate system the coordinates of {B} (^B X_i,^B Y_i,^B Z_i);

(G) repeating (f) step, to obtain on the surface of the object points in the laser stripe (according to the accuracy requirement, a certain spacing distance a point) in the base coordinate system the coordinates of the {B};

(H) motor 5 driving the rotating shaft 6 to rotate to the other angular position, repeating (e), (f), (g) step, is observed through the video camera and can be the laser stripe projected onto the object surface under the somewhat in the base coordinate system of the coordinate value of the, complete the measuring.

Detailed further below use chart 1 or Figure 7 shown in the method for measuring the embodiment.

(A) according to the following method to establish the Image coordinate system {P}, {A} coordinate system as the target, the camera coordinate system {C}, {W} base coordinate system and laser coordinate system {L}, coordinate system a schematic diagram as shown in Figure 5 and Figure 6.

(A1) the establishment of the Image coordinate system {P}: the camera 2 defined on the photographed Image with a like target surface 16 fixedly connected with the two-dimensional rectangular coordinate system, referred to as the Image coordinate system {P}, whose origin O_p the upper left corner of the Image, referred to as shaft x u shaft thereof, the right horizontally in a direction, called v shaft y shaft thereof, vertical downward direction, sitting for said (u, v), respectively and u v the pixel point in the Image and the number of number, the unit is a pixel.

(A2) establishment of a like target surface coordinate system {A}: camera 2 the optical axis of lens L_c and a target surface 16 the crossingpoint O_a point referred to as the picture center, to O_a to initial point, in the direction of shaft is u x_a-axis positive direction, the direction is in the axis is positive to v y_a-axis positive direction, as with the creation of a target face 16 of a two-dimensional rectangular coordinate system is, as the target referred to as {A} coordinate system.

(A3) establishment of a camera coordinate system {C}: to camera 2 of the optical center of the lens O_c as the origin, to the optical axis of the lens of the camera L_c to Z_c shaft, to camera 2 for viewing the front side Z_c direction, to x_b shaft is positive direction is X_c shaft is positive direction, to y_b shaft is positive direction is Y_c shaft is positive direction, with the creation of a video camera 2 of the three-dimensional rectangular coordinate system is fixed, known as the camera coordinate system {C}.

(A4) establishing a base coordinate system {B}: with the creation of a base 1 of the three-dimensional rectangular coordinate system is fixed, known as the base coordinate system {B}, to the rotating shaft 6 the centerline L₁ to Z_b shaft, the surface of the object from the measured 20 is directed to a word line laser 3 to the direction of Z_b shaft is positive direction.

The original point O_b, X_b and Y_b determination method is as follows: as shown in Figure 5, is placed a plane D referred to as calibration plane, the distance of d laser printing, such as a square grid, placed in on the calibration plane D, a word line laser 3 projected laser in the plane of the word to form a linear laser stripe 17 ; adjusting calibration plane D such that when the rotating shaft 6 is rotated in the obtained Image from the camera in the word linear laser stripe 17 {P} in the Image coordinate system always in the same position of the, plane D note at this moment has been perpendicular to the rotating shaft 6 of the center line.

In the device is in the 0° position, that is, angle measuring element 7 measured rotating shaft 6 is the angle of rotation of the the 0 °, to plane D the axis of rotation 6 as the origin the intersection of O_b, origin O_b that is, the rotating shaft 6 in the plane of rotation of the laser to form different projected D the laser stripe of the intersection of the direction, of the linear laser light in a plane for the stripe on D X_b shaft, a hidden waist belt are direction is positive direction, the right for Z_b and X_b determining Y_b shaft.

(A5) establishing a laser coordinate system {L} : {L} laser coordinate system is fixedly connected to the laser; when the device is in the 0° position, laser coordinate system with the base coordinate system {L} with {L}; θ when the device is located at the angle position, that is, angle measuring element 7 measured rotating shaft 6 to the rotation angle of the angle θ, as shown in Figure 6, base coordinate system {B} around its Z_b shaft rotates to a new coordinate system generated by the angle θ is to laser coordinate system {L}.

(B) according to the following method calibration Image coordinate system {P}, {A} coordinate system as the target, the camera coordinate system {C}, a base coordinate system and laser coordinate system {B} {L} the coordinate transformation relations between.

(B1) with the Image coordinate system {P} {A} coordinate system as the target surface is the relationship between:

xjA y j A 1 = k u 0 - u 0 0 k v - v 0 0 0 1 u j v j 1 = K u j v j 1 ,    ( Formula 1)

In the formula, k_u, k_v are respectively like target surface 16 a of the pixel v u shaft and along the length of the axial direction, the unit is mm, k_u, k_v is provided by the camera manufacturer of the camera an important parameter. (u₀, v₀) to the camera 2 to the optical axis of lens L_c and a target surface 16 the crossingpoint O_a in the Image coordinate system the coordinates of the {P}, (u₀, v₀) can be obtained by the Image center calibration experiment. Integrated, matrix representative of K relative to the Image coordinate system {P} {A} target coordinate system as the homogeneous coordinates transformation matrix, the camera internal parameter K is a fixed value determined by the prior calibration experiments, (^A x_j,^A y_j) i a certain point corresponding to the representative of the camera as the target face 16 as Image point on the j target coordinate system the coordinates of {A}, (u_j, v_j) representative point j in the Image coordinate system the coordinates of {P}.

(B2) like target surface coordinate system to the camera coordinate system {A} relationship to the {C}:

ZiC x j A y j A 1 = f 0 0 0 0 f 0 0 0 0 1 0 X i C Y i C Z i C 1 = F X i A Y i C Z i C 1 ,    ( Formula 2)

In the formula, f to the camera 2 to the lens focal length, f is a known fixed value, (^C X_i,^C Y_i,^C Z_i) representative i a certain point in the camera coordinate system the coordinates of {C};

(B3) camera coordinate system {C} with the laser coordinate system in relationship to the {L}:

XiC Y i C Z i C 1 = R 11 R 12 R 13 X L C R 21 R 22 R 23 Y L C R 31 R 32 R 33 Z L C 0 0 0 1 X i L Y i L Z i L 1 = T L C X i L Y i L Z i L 1 ,    ( Formula 3)

Or expressed as:

XiL Y i L Z i L 1 = T C L X i C Y i C Z i C 1 = ( T L C ) - 1 X i C Y i C Z i C 1 = t 11 t 12 t 13 t 14 t 21 t 22 t 23 t 24 t 31 t 32 t 33 t 34 0 0 0 1 X i C Y i C Z i C 1    ( Formula 4)

In the formula, (^L X_i,^L Y_i,^L Z_i) representative i point in the laser coordinate system the coordinates of {L}, (^C X_L,^C Y_L,^C Z_L) representative laser coordinate system, the origin of the {L} O_L the camera coordinate system the coordinates of {C}.

In the formula, matrix R11R12R13R21R22R23R31R32R33Representative laser coordinate system to the camera coordinate system {L} {C} attitude transformation matrix,^C T_L representative laser coordinate system to the camera coordinate system {L} {C} the homogeneous coordinates transformation matrix,^C T_L external parameters by the camera is pre-determined fixed value of calibration experiment,^L T_C is^C T_L the inverse of, obtained can be calculated.

(B4) base coordinate system {W} and laser coordinate system in relationship to the {L}:

XiB Y i B Z i B 1 = Cos [! Theta! ] - Sin [! Theta! ] 0 0 Sin [! Theta! ] Cos [! Theta! ] 0 0 0 0 1 0 0 0 0 1 X i L Y i L Z i L 1 = T L B X i L Y i L Z i L 1 ,    ( Formula 5)

In the formula, (^B X_i,^B Y_i,^B Z_i) representative i point in the laser coordinate system the coordinates of {B};

(C) laser plane S in the laser coordinate system {L} in the equation as:y_L = 0, recombines formula 4, the laser plane S may be deduced in the camera coordinate system {C} in the equation:

t₂₁ x_c +t₂₂ y_c +t₂₃ z_c +t₂₄ = 0,   (formula 6)

(D) a motor 5 driving the rotating shaft 6 to rotate to the angle position θ, as shown in Figure 6.

(E) through the angle measuring element 7 of the angle values measured; a word line laser 3 emits a word linear laser light is formed on the surface of the measured object to a stripe, camera 2 of the stripe containing the shot Image on the object surface.

(F) Image processing Image stripe point j on the Image coordinate system of the coordinate of the {P} (u_j, v_j); by coordinate conversion target point j of the coordinate system the coordinates of {A} (^A x_j,^A y_j); coordinate conversion point j with the counterpart obtained i determined point imaging linear L_i in the camera coordinate system {C} the straight-line equation of the, combination (c) step of the laser plane equation, imaging the straight line and by the intersection of the laser plane i the camera coordinate system the coordinates of {C} (^C X_i,^C Y_i,^C Z_i), i point coordinate conversion obtained in the laser coordinate system the coordinates of {L} under (^L X_i,^L Y_i,^L Z_i), i coordinate conversion by the base point of the coordinate system the coordinates of {B} (^B X_i,^B Y_i,^B Z_i).

The specific process is as follows:

Entry i the upper to a certain point, its corresponding to the Image of the point j, j point by the Image processing by the Image coordinate system of the coordinate of the {P} (u_j, v_j);

The (u_j, v_j) formula 1 to obtain the target point j of the coordinate system the coordinates of {A} (^A x_j,^A y_j);

The (^A x_j,^A y_j) formula 2, and simultaneously the formula 6, i point obtained in the camera coordinate system the coordinates of {C} (^C X_i,^C Y_i,^C Z_i):

XiC X i C X i C = x i A x i A f - t 24 t 21 x i A + t 22 y i A + Ft 23 ;    ( Formula 7)

The (^C X_i,^C Y_i,^C Z_i) formula 4, must solve the i a word line under the laser coordinate system the coordinates of {L} (^L X_i,^L Y_i,^L Z_i);

The (^L X_i,^L Y_i,^L Z_i) formula 5, solve the i point in the base coordinate system the coordinates of the {B} (^B X_i,^B Y_i,^B Z_i).

On the surface of the object thus obtained in the laser stripe arbitrary point of the base i the coordinate system the coordinates of {B} (^B X_i,^B Y_i,^B Z_i).

(G) repeating (f) step, to obtain on the surface of the object points in the laser stripe (according to the accuracy requirement, a certain spacing distance a point) in the base coordinate system the coordinates of the {B};

(H) motor 5 driving the rotating shaft 6 to rotate to the other angular position, repeating (e), (f), (g) step, is observed through the video camera and can be the laser stripe projected onto the object surface under the somewhat in the base coordinate system of the coordinate value of the, complete the measuring.

In this embodiment, camera coordinate system {C} with the laser coordinate system the relationship between {L}^C T_L calibration experiment, known as the camera external parameter calibration experiment, the experimental method public known technology, a plurality of specific method. The use of this embodiment of a more commonly used camera external parameter calibrating experimental method.

As shown in Figure 6, calibration plane D is, on the distance of d a square grid, a word line laser 3 projected laser in the plane of the word to form a linear laser stripe 17 ; adjusting the plane so that when the rotating shaft 6 is rotated in the obtained Image from the camera in the word linear laser stripe 17 in the Image coordinate system is always under the same position, note the plane perpendicular to the rotating shaft have been D 6 the central line. In the device is in the 0° position, at this moment the base coordinate system with the laser coordinate system {B} with {L}. At this moment, the calibration camera coordinate system with the laser coordinate system {C} {L} (at this time, the base coordinate system {B}) relationship.

Square mesh lattice crossingpoint in the laser coordinate system {L} to the coordinate value of the known: any point on the plane because the i^L Z coordinate is 0, the laser stripe in^L X shaft,^L X the axial direction of the known, origin O_L (initial position and O_b coincide) and the known position of the stripe, origin O_L that is, the rotating shaft 6 in the plane of rotation of the laser projected D form different intersection point of the laser stripe of direction.

Using plane D as the meshes of the characteristic point of intersection.

The is provided with a grid crossingpoint i the homogeneous coordinates of {L}^L P_i = [^L X_i^L Y_i^L Z_i   1]^T, {C} in the homogeneous coordinates under^C P_i = [^C X_i^C Y_i^C Z_i   1]^T. {C} {L} relationship with as the formula 3 as shown.

Q^L Z_i = 0, formula 3 into:

XiC = R 11 X i L + R 12 Y i L + X L C Y i C = R 21 X i L + R 22 Y i L + Y L C Z i C = R 31 X i L + R 32 Y i L + Z L C    ( Formula 8)

The formula 2 may be

XiC = x i A f Z i C Y i C = y i A f Z i C    ( Formula 9)

The formula 8 of in^C Z_i,^C X_i,^C Y_i into the (formula 9) to be

R11XiL + R 12 Y i L + X L C = x i A f ( R 31 X i L + R 32 Y i L + Z L C ) R 21 X i L + R 22 Y i L + Y L C = y i A f ( R 31 X i L + R 32 Y i L + Z L C )    ( Formula 10)

Finishing formula 10 shall be

fLXiR11+fLYiR12-xiA X i L R 31 - x i A Y i L R 32 + f C X L = i x i A Z L C f L X i R 21 + f L Y i R 22 - y i A X i L R 31 - y i A Y i L R 32 + f C Y L = y i A Z L C    ( Formula 11)

The formula 11 type two edge same divided by^C Z_L (Q^C Z_L ≠ 0), get

fLXiR11ZLC + f L Y i R 12 Z L C - x i A X i L R 31 Z L C - x i A Y i L R 32 Z L C + f C X L Z L C = x i A f L X i R 21 Z L C + f L Y i R 22 Z L C - y i A X i L R 31 Z L C - y i A Y i L R 32 Z L C + f C Y L Z L C = y i A    ( Formula 12)

The formula 12 type written in matrix form:

   ( Formula 13)

Wherein

Ai=fLXifLYi00-xiA X i L - x i A Y i L f 0 0 0 f L X i f L Y i - y i A X i L - y i A Y i A 0 f

From the formula 13 as can be seen in, because the With 8 a factory overhaul, therefore, needs at least 4 points (8 equation a), can only be solved

In order to overcome the influence of noise, the feature point of introducing redundancy (such as the far more than 4 feature point a) in order to reduce the error of position estimation, and the least squares method, the smallest error squares. Therefore,

   ( Formula 14)

wherein A= [A₁   A₂   L   A_n]^T, The number of n for characteristic point.

when the After being calculated, through the rotation matrix^L R_C units can be soly while orthogonal nature^C Z_L:

R112+R212+R312=1R122+R222+R322=1   ( Formula 15)

Because^C Z_L > > f > 0,

or    ( Formula 16)

Wherein is Section i elements. Formula 15 calculated in the two formulae^C Z_L not necessarily equal, therefore, its average value as a^C Z_L value. Get^C Z_L value, will^C Z_L substituted Can be obtained in each element of:

   ( Formula 17)

Conjunction with the rotational matrix^C R_L orthogonal nature of the units, to obtain:

R13=1-R112-R122R23=1-R212-R222R33=1-R312-R322,   ( Formula 18)

The experiment used for calibration of a number of characteristic points (i.e. horizontal D a plurality of grid crossingpoint) in O_L X_L Y_L plane. These feature point coordinates {L} of the completely known. They the camera imaging of the Image points completely lower coordinates {A} known. To this, by formula 14, formula 15, formula 16 and formula 17 solving the {C} the coordinate system with the relationship between {L}^C T_L, the calibrating process is completed.

Because the device of the invention the projected laser stripe is a rotary scanning, traditional fixed direction effectively overcome the deficiency of the laser stripe method, can detect the edge information of the various directions, realizing high-precision measurement of the three-dimensional topography of the surface of the object; since the camera together with a word line laser rotation, always keep the relative attitude optimum posture, so as to ensure the good measuring accuracy; the center line of the rotation axis due to the linear laser plane after a word, the rotary shaft rotates one cycle, the laser stripe will not blind zone to sweep across the surface of the measured object, at the same time, simplifies the calibration and measurement process; due to the device of the invention uses a word line measuring the laser device and the camera head to rotate, to avoid the traditional method of assembly by the rotation of the object, is suitable for various size of the detection surface of the object. The device of the invention has simple structure, low cost, high measuring precision, not only can be used as a fixing device, can also be installed in the mobile robot.