CN103063213B - The scaling method of a kind of welding robot and positioner position orientation relation - Google Patents

Abstract

The invention provides the scaling method of a kind of welding robot and positioner position orientation relation, definition positioner sloping shaft is Z axis, and turning axle is Y-axis, and coordinate origin is the intersection point O of rotating shaft axis and sloping shaft axis, with Y, Z axis is vertical and another axle meeting the right-hand rule is X-axis.Positioner is made to rotate to multiple position respectively around turning axle and sloping shaft respectively by robot controller, record TCP point correspondence position pose data and set up spherical equation, based on the optimum sphere of least square fitting, thus try to achieve positioner coordinate origin.Then adopt and use the same method, allow TCP point make polymarker in positioner two axis, the method based on vector multiplication cross can try to achieve the direction vector of each coordinate axis further, thus realizes position orientation relation demarcation.The present invention is the impact eliminating accidentalia, proposes range deviation rate concept and set to get a threshold determination method, improves stated accuracy.

Description

The scaling method of a kind of welding robot and positioner position orientation relation

Technical field

The present invention relates to laser bonding processing cutting field, the position orientation relation scaling method of especially a kind of laser melting coating robot and outside axle, the position orientation relation scaling method specifically between a kind of welding robot and 2 axle positioners.

Background technology

Laser remanufacturing process take laser melting coating as recovery technique platform, in conjunction with rapid laser-shaping technique and modern advanced manufacturing technique, repairs and improve part.Laser remanufacturing robot is the height integrated system based on laser technology and Robotics, and robot is coupled with laser instrument by it, has good processing flexibility.Robot provides five or six programmable kinematic axiss, and its effective working space and admissible space are subject to the restriction of kinematical constraint, therefore needs to utilize the utility appliance such as positioner to provide redundant degree of freedom, as shown in Figure 1.

Based on the laser remanufacturing system of robot, the demarcation of robot and positioner position orientation relation is the prerequisite of the efficient coordinated movement of various economic factors of robot and positioner, is also the practical key of off-line programming technique.The holy auspicious Master's thesis " arc welding robot off-line programing practical research " of Harbin Institute of Technology Liu proposes 5 standardizations based on revolving the positioner that inclines, and record TCP point, in the pose data of five different positions, can realize demarcation by calculating.The method is simple and quick, but is subject to the impact of accidentalia, and stochastic error is comparatively large, is difficult to the demand meeting high-precision laser cladding.Propose the sphere surface fitting standardization based on least square method in literary composition, robot and the position orientation relation revolving the positioner that inclines are demarcated.

Carrying out surface modification by laser melting and coating technique to important parts is reduce costs, put forward the very important means of high performance one, but some curve surface of workpiece are very complicated, accessory size is large, 6 degree of freedom of robot itself are only relied on to be difficult to the motion effectively completing this complexity, its effective working space and admissible space are subject to the restriction of kinematical constraint, therefore need to utilize the utility appliance such as positioner to provide redundant degree of freedom.The demarcation of robot and positioner position orientation relation is the prerequisite of the efficient coordinated movement of various economic factors of robot and positioner, is also the practical key of off-line programming technique.

Summary of the invention

The object of the invention is to for the deficiencies in the prior art and defect, a kind of laser melting coating robot and the pose scaling method revolving the diaxon positioner that inclines are provided, there is higher precision, meet the practical application need of production of the off-line programing of high-precision laser cladding completely.

According to an aspect of the present invention, the scaling method of a kind of welding robot and positioner position orientation relation is provided, comprises the steps:

Step 1: make positioner rotate to multiple position respectively around turning axle and sloping shaft respectively by robot controller, record TCP point correspondence position pose data and set up spherical equation, based on the optimum sphere of least square fitting, thus try to achieve positioner coordinate origin;

Step 2: make positioner rotate to multiple position respectively around turning axle and sloping shaft respectively by robot controller, allow TCP point positioner turning axle axially and sloping shaft axis make polymarker, method based on vector multiplication cross tries to achieve the direction vector of each coordinate axis further, thus realizes position orientation relation demarcation.

Preferably, the described method based on vector multiplication cross tries to achieve the step of the direction vector of each coordinate axis further, is specially, and first allows positioner be in the zero-bit of turning axle and sloping shaft, and TCP point is overlapped with positioner gauge point, records TCP position now; Then make positioner move to two new positions around turning axle, make TCP point overlap with gauge point respectively, record the position of now TCP; Then keep the position of current turning axle motionless, allow positioner rotate to two different positions around sloping shaft, and robot TCP point is overlapped with gauge point, record the position data of now TCP; Then obtain the normal vector perpendicular to this plane based on two different vector multiplication cross on same plane, try to achieve the direction vector of positioner coordinate axis respectively.

Preferably, when asking for the direction vector of coordinate axis, if taken point to the distance value of coordinate origin and expectation value difference comparatively large, then again get a little; Wherein, the method adopted is the method for error threshold, when the difference of actual value and expectation value to be greater than the threshold value of setting divided by expectation value, then again get a little, this enters the method can effectively reduce stochastic error, avoids the impact of accidentalia, has higher stated accuracy.

Preferably, described step 1 specifically comprises the steps:

Step 1.1: first do a gauge point on positioner chuck, as positioner sloping shaft J ₂when being in 0 ° ,-40 ° ,-30 ° ,-20 ° ,-10 °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, perform step: arrange positioner coordination function, positioner is active set, artificial driven group of machine; Teaching robot TCP point overlaps with gauge point, enables displacement coordination function, makes positioner around turning axle J ₁rotate, in the process of motion, TCP point can remain and to overlap with gauge point; Positioner turns to 20 positions at random, records the pose data of corresponding TCP point;

Step 1.2: by the TCP point pose data preparation gathered, set up spherical surface error equation, based on the quadratic sum minimum principle of least square method error, set up system of linear equations thus try to achieve the position of the centre of sphere in basis coordinates system of robot and spherical radius, wherein, the described centre of sphere is positioner base system initial point.

Preferably, described step 2 specifically comprises the steps:

First make sloping shaft J ₂be in zero-bit, positioner turning axle J ₁rotate two angles, gauge point arrives two different positions respectively, and teaching robot TCP overlaps with gauge point; Allow turning axle J ₁motionless, sloping shaft J ₂vert respectively two angles, gauge point arrives two different positions, and then teaching robot TCP point overlaps with gauge point, the position data of recording mark point in robot coordinate system; Make according to two vectors on same plane the direction vector that multiplication cross can obtain perpendicular to this plane, try to achieve each change in coordinate axis direction vector of positioner basis coordinates system further.

In preferred scheme, positioner be 2 axles revolve the positioner that inclines, one is the turning axle rotated around horizontal direction, and one is the sloping shaft rotated around vertical direction, and two axles are the outside axle of robot, be convenient to robot and positioner carries out the coordinated movement of various economic factors by robot controller, set up positioner basis coordinates system, sloping shaft is Z axis, and turning axle is Y-axis, coordinate origin is the intersection point O of rotating shaft axis and sloping shaft axis, vertical with Y-axis, Z axis and another axle meeting the right-hand rule is X-axis.Taking up an official post at positioner chuck gets a bit, and no matter positioner rotates around tilting axis or around turning axle, and this point remains constant to the distance of positioner coordinate origin O point.Namely this point is taking initial point as the centre of sphere, and the distance to initial point is on the sphere of radius.Based on this rule, can by positioner chuck a bit rotating respectively with positioner or tilting to multiple position, record TCP point correspondence position pose data and set up spherical equation, adopt least square fitting optimum sphere, thus try to achieve positioner coordinate origin.Then adopt and use the same method, TCP point is allowed to make polymarker in positioner two axis, the direction vector that multiplication cross can obtain perpendicular to this plane is made according to two vectors at grade, the direction vector of each axle of coordinate system can be tried to achieve further, thus obtain the module and carriage transformation matrix of positioner relative to basis coordinates system of robot, thus realize the demarcation of positioner position orientation relation.For eliminating the impact of accidentalia, proposing range deviation rate concept and setting and getting a threshold determination method, further increasing stated accuracy.

The present invention to adopt on chuck multiple spot coordinate figure when a bit moving to diverse location with positioner, then positioner coordinate origin is tried to achieve based on the optimum sphere of least square fitting, and obtain change in coordinate axis direction vector by polymarker method employing vector multiplication cross thus realize the position orientation relation demarcation of robot positioner, and when when asking direction vector to get, if taken point exceedes the deviation ratio threshold value of setting, need again to get a little, further increase the accuracy of demarcation.Obviously improve a lot relative to " three point method " or " five-spot " stated accuracy only getting three points or five points of routine, after demarcating, the program of off-line programing does not need to revise or only need little correction just can be directly used in and produces reality, be convenient to the practical application of off-line programing program, there is larger practical value.

Accompanying drawing explanation

By reading the detailed description done non-limiting example with reference to the following drawings, other features, objects and advantages of the present invention will become more obvious:

Fig. 1 is the definition of positioner coordinate system;

Fig. 2 is positioner labeling process schematic diagram;

Fig. 3 is the sphere method fitting result based on least square method.

Embodiment

Below in conjunction with specific embodiment, the present invention is described in detail.Following examples will contribute to those skilled in the art and understand the present invention further, but not limit the present invention in any form.It should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, some distortion and improvement can also be made.These all belong to protection scope of the present invention.

(1) first step, fit sphere method ask coordinate origin

As shown in Figure 1, the sloping shaft that the present invention defines positioner basis coordinates system is axially Z-direction, and turning axle is axially Y direction, vertical with Y-axis, Z axis and another axle meeting the right-hand rule is X-axis, and true origin is the intersection point O of rotating shaft axis and sloping shaft axis.

If treat that the fit sphere centre of sphere is O(A, B, C), radius is R.Take up an official post at positioner chuck and get 1 A, teaching robot TCP point overlaps with A point, enables displacement coordination function.Control positioner around turning axle J ₁rotate, in the process of motion, TCP point can remain and to overlap with A point.Positioner turns to 20 positions at random, records the pose data of now TCP point.

And then allow positioner sloping shaft J ₂be in respectively-40 ° ,-30 ° ,-20 ° ,-10 °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 ° angularly time, robot and the positioner coordinated movement of various economic factors, recorder people TCP is corresponding pose data when positioner all angles.

If the data point set gathered is P _i(X _i, Y _i, Z _i), 1≤i≤N, treats that the fit sphere centre of sphere is O(A, B, C), radius is R, and each point is D to the distance of the centre of sphere _i, then

$D_i=\sqrt{{(X_i-A)}^2+{(Y_i-B)}^2+{(Z_i-C)}^2}---\left(1\right)$

Assuming that a=-2A, b=-2B, c=-2C, d=-R ²+ A ²+ B ²+ C ², then based on least square fitting sphere, following error equation is set up

$Q(a,b,c,d)=\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{\mathrm{\δ}}_i^2=\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{(D_i^2-R^2)}^2=\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{(X_i^2+Y_i^2+Z_i^2-{2\mathrm{AX}}_i-{2\mathrm{BY}}_i-{2\mathrm{CZ}}_i+d)}^2---\left(2\right)$

Wherein, ${{\mathrm{\δ}}_i}^2={(D_i^2-R^2)}^2.$

From formula (2), difference of two squares function Q (a, b, c, d) is greater than 0, and therefore this function exists the minimal value being more than or equal to 0, and maximum value is infinitely great.Q (a, b, c, d) asks local derviation to a, b, c, d respectively make partial derivative equal 0, with a, b, c as known variables to be asked, set up system of linear equations, then can try to achieve the sphere centre coordinate O(A of sphere according to Cramer's rule, B, C) (i.e. positioner basis coordinates system initial point) and spherical radius R.

Fig. 2 is for adopting sphere surface fitting method to ask coordinate origin O(A, B, C based on least square method) and the result of spherical radius R test schematic diagram.

(2) second step, polymarker method ask change in coordinate axis direction vector

Make positioner sloping shaft J ₂be in zero-bit, turning axle J ₁rotate two angles, gauge point is in-position A respectively ₁, A ₂, teaching robot TCP point overlaps with gauge point.Then turning axle J ₁motionless, sloping shaft J ₂to vert respectively two angles, gauge point in-position A ₃, A ₄, teaching TCP point overlaps with gauge point, the pose data of recording mark point in basis coordinates system of robot.Labeling process as shown in Figure 3.

By the definition of aforesaid positioner coordinate system, and the geometric relationship between gauge point, known A, A ₁, A ₂3 planes determined are axially vertical with turning axle, A ₂, A ₃, A ₄3 planes determined are axially vertical with sloping shaft.

It can thus be appreciated that the Y direction unit vector of positioner basis coordinates system is

$j=\frac{\stackrel{\→}{A_1{A}_2}\×\stackrel{\→}{{\mathrm{AA}}_1}}{|\stackrel{\→}{A_1{A}_2}\×\stackrel{\→}{{\mathrm{AA}}_1}|}---\left(3\right)$

Z-direction unit vector is

$k=\frac{\stackrel{\→}{A_2{A}_3}\×\stackrel{\→}{{A_{3}A}_4}}{|\stackrel{\→}{A_2{A}_3}\×\stackrel{\→}{A_3{A}_4}|}---\left(4\right)$

X-direction can be tried to achieve by orthogonality relation, and its unit vector is

$i=\stackrel{\→}{j}\×\stackrel{\→}{k}---\left(5\right)$

In conjunction with the coordinate origin of trying to achieve, thus the module and carriage transformation matrix of positioner basis coordinates system relative to basis coordinates system of robot can be obtained above

$T_P^R=\left[\begin{array}{cccc}{i}_x& i_y& i_z& A\\ j_x& j_y& j_z& B\\ k_x& k_y& k_z& C\\ 0& 0& 0& 1\end{array}\right]---\left(6\right)$

I (i in formula _x, i _y, i _z) be x-axis unit vector, j (j _x, j _y, j _z) be y-axis unit vector, k (k _x, k _y, y _z) be z-axis unit vector, O(A, B, C) be true origin.

The present invention gathers multiple data point respectively at two axles, then positioner coordinate origin is tried to achieve based on the optimum sphere of least square fitting, then obtain change in coordinate axis direction vector by the method for polymarker method employing vector multiplication cross thus realize the position orientation relation demarcation of robot positioner, and when when asking direction vector to get, if taken point exceedes the deviation ratio threshold value of setting, need again to get a little, further increase the accuracy of demarcation.Stated accuracy is high, is convenient to the practical application of off-line programing program, has larger practical value.

Above specific embodiments of the invention are described.It is to be appreciated that the present invention is not limited to above-mentioned particular implementation, those skilled in the art can make various distortion or amendment within the scope of the claims, and this does not affect flesh and blood of the present invention.

Claims (5)

1. a scaling method for welding robot and positioner position orientation relation, is characterized in that, comprises the steps:

Step 1: make positioner rotate to multiple position respectively around turning axle and sloping shaft respectively by robot controller, record TCP point correspondence position pose data and set up spherical equation, based on the optimum sphere of least square fitting, thus try to achieve positioner coordinate origin; Wherein, positioner basis coordinates system's initial point and spherical radius is tried to achieve according to Cramer's rule;

Step 2: make positioner rotate to multiple position respectively around turning axle and sloping shaft respectively by robot controller, allow TCP point positioner turning axle axially and sloping shaft axis make polymarker, method based on vector multiplication cross tries to achieve the direction vector of each coordinate axis further, thus realizes position orientation relation demarcation.

2. the scaling method of welding robot according to claim 1 and positioner position orientation relation, it is characterized in that, the described method based on vector multiplication cross tries to achieve the step of the direction vector of each coordinate axis further, be specially, positioner is first allowed to be in the zero-bit of turning axle and sloping shaft, and TCP point is overlapped with positioner gauge point, record TCP position now; Then make positioner move to two new positions around turning axle, make TCP point overlap with gauge point respectively, record the position of now TCP; Then keep the position of current turning axle motionless, allow positioner rotate to two different positions around sloping shaft, and robot TCP point is overlapped with gauge point, record the position data of now TCP; Then obtain the normal vector perpendicular to this plane based on two different vector multiplication cross on same plane, try to achieve the direction vector of positioner coordinate axis respectively.

3. the scaling method of welding robot according to claim 2 and positioner position orientation relation, is characterized in that, when asking for the direction vector of coordinate axis, if taken point to the distance value of coordinate origin and expectation value difference comparatively large, then again get a little; Wherein, the method adopted is the method for error threshold, when the difference of actual value and expectation value to be greater than the threshold value of setting divided by expectation value, then again gets a little.

4. the scaling method of welding robot according to claim 1 and positioner position orientation relation, is characterized in that, described step 1 specifically comprises the steps:

Step 1.1: first do a gauge point on positioner chuck, as positioner sloping shaft J ₂when being in 0 ° ,-40 ° ,-30 ° ,-20 ° ,-10 °, 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, perform step: arrange positioner coordination function, positioner is active set, artificial driven group of machine; Teaching robot TCP point overlaps with gauge point, enables displacement coordination function, makes positioner around turning axle J ₁rotate, in the process of motion, TCP point can remain and to overlap with gauge point; Positioner turns to 20 positions at random, records the pose data of corresponding TCP point;

Step 1.2: by the TCP point pose data preparation gathered, set up spherical surface error equation, based on the quadratic sum minimum principle of least square method error, set up system of linear equations thus try to achieve the position of the centre of sphere in basis coordinates system of robot and spherical radius, wherein, the described centre of sphere is positioner base system initial point.

5. the scaling method of welding robot according to claim 1 and positioner position orientation relation, is characterized in that, described step 2 specifically comprises the steps:

First make sloping shaft J ₂be in zero-bit, positioner turning axle J ₁rotate two angles, gauge point arrives two different positions respectively, and teaching robot TCP overlaps with gauge point; Allow turning axle J ₁motionless, sloping shaft J ₂vert respectively two angles, gauge point arrives two different positions, and then teaching robot TCP point overlaps with gauge point, the position data of recording mark point in robot coordinate system; Make according to two vectors on same plane the direction vector that multiplication cross can obtain perpendicular to this plane, try to achieve each change in coordinate axis direction vector of positioner basis coordinates system further.