CN1288601C - Method for conducting path planning based on three-dimensional scatter point set data of free camber - Google Patents

Abstract

The present invention relates to a route planning method based on three-dimensional scattered point set data of a free curved surface. In the method, scattered data of a free curved surface is interpolated and reconstructed so that three-dimensional discrete data points are fit into a triangle Bernstein-Be zier curved surface; six-dimensional trajectory planning is carried out on the obtained interpolation curved surface through the triangle Bernstein-Be zier curved surface; for trajectory planning in an arbitrary direction, coordinates in the direction can be converted into coordinates in the x-y direction to obtain trajectory planning; the triangle Bernstein-Be zier curved surface is a cubic triangle Bernstein-Be zier curved surface. In the method of the present invention, the triangle Bernstein-Be zier curved surface is used for fitting the free curved surface of the three-dimensional scattered point set data and planning six dimensional processing trajectories on the interpolation curved surface; consequently, the route planning of three-dimensional scattered point set data of an arbitrary free curved surface is realized.

Description

Carry out the method for path planning based on the 3 d discrete point collection data of free form surface

Technical field

The present invention relates to the computer control field of integrated Laser Processing, particularly a kind of method of carrying out path planning based on the 3 d discrete point collection data of free form surface.

Background technology

In the prior art, laser surface intensified require laser beam axis be laser Machining head perpendicular to finished surface, like this, during machining path, not only need to obtain the three-dimensional space position of processing stand, and need the pairing method vector of processing stand in planning.At present, with the 3 d-dem data of free form surface Data Source as system, realization is to be the free form surface of this space scattered data being of basic match with B-Spline or nurbs surface to the main method of the laser surface intensified path planning of free form surface, then, correspondingly finish the planning of sextuple track with B-Spline or nurbs surface; But used space scattered data being must be equidistant, uniformly when being basic match free form surface with B-Spline or nurbs surface, can not handle any 3 d discrete point collection data.Therefore, adopting B-Spline or nurbs surface is that the path planning that carries out of basic fitting surface has significant limitation.

For example, patent No. US5363479, exercise question has been described the system and method for simulation B in computer graphics system for the United States Patent (USP) of " SYSTEM AND METHOD FOR RENDERINGBEZIER SPLINES ", this patent is approached B by limited many straight-line segments that generated by the vector plus-minus, this method is confined to the processing to curve, and the discrete straight-line segment that obtains is non-isometric, can not be applied to the reinforcement of laser surface; Patent No. US5818459, exercise question has been described a kind of instrument that the cubic fit curve is automatically converted to the twice fitting curve for the United States Patent (USP) of " DATA CONVERSION APPARATUS AND METHODUSING CONTROLPOINTS OF ACURVE ", be device, do not meet laser surface intensified requirement equally curve processing; Patent No. JP10198812, exercise question has been described a method of approaching the optimization free form surface on any border with nurbs surface for the patent of " APPROXIMATING METHOD FOR FREE-FORMSURFACE ", this method is that the four edges circle curvilinear transformation with original curved surface becomes three B-Spline curves to realize free form surface is approached a nurbs surface, patent in conjunction with two three B-Spline curves of a knot vector correspondence with the free form surface gridding that is approached, each grid is approached by a continuous Besizer curved surface of three C1 simultaneously, like this, all three Besizer curved surfaces are connected to a nurbs surface, and the process of this surface fitting does not relate to path planning problem.

Summary of the invention

The objective of the invention is to: the method that overcomes the laser surface intensified path planning of existing free form surface can only be that the basis comes fitting surface to carry out path planning with equidistant space scattered data being uniformly, can not handle any 3 d discrete point collection data, therefore, adopt the free form surface of B-Spline or nurbs surface match space three-dimensional point at random that bigger limitation is arranged in the use, thereby a kind of Laser Surface Treatment system that is used for is provided, carries out the method for path planning based on the 3 d discrete point collection data of free form surface.

The object of the present invention is achieved like this: a kind of method of carrying out path planning based on the 3 d discrete point collection data of free form surface of the present invention, this method is in the Laser Surface Treatment system, by the scattered data being interpolation reconstruction of industrial computer to free form surface, the 3 d-dem data point is fitted to triangle Bernstein-B é zier curved surface, utilize triangle Bernstein-B é zier curved surface that the interpolation curved surface that obtains is carried out sextuple trajectory planning again, at last, move by the sextuple track data control robot of industrial computer output free form surface.

This method handles to obtain sextuple track data and output to robot by industrial computer in the Laser Surface Treatment system, and control robot drives the laser instrument processing head that is fixed on its arm and move according to sextuple track data, and its step comprises:

(1) after industrial computer receives the 3 d discrete point collection data of free form surface, utilizes triangle Bernstein-B é zier curved surface to carry out the interpolation curved surface that match obtains 3 d discrete point collection data, obtain the space triangular topological relations;

(2) this space triangular topological relations is projected to the xy plane, get on the triangular topological relations of space (x, the y) coordinate, and determine rectangular area (x that point is concentrated every bit with this by industrial computer _Min, y _Min), (x _Max, y _Max);

(3) with a p ' ₁=(x _Min, y _Min) be starting point, along the y direction of principal axis get successively form a point set p ' _k, p ' _k=(x _Min, y _Min+ (k-1) * d), (k=1,2 ..., n), wherein, d is the distance between two points that requirement is determined according to difference, until point (x _Min, y _Max); According to the resulting space of step (1) triangular topological relations, obtain p ' again _kCorresponding point p on triangular topological relations _k(x _k, y _k, z _k), form point set { p _k;

(5) according to { p _kEach point of concentrating of point and calculate with { p _k(u, v w), utilize triangle Bernstein-B é zier curved surface to calculate sextuple point set { l on the corresponding triangular surface for center of gravity parameter in the corresponding triangular domain of point set _k}={ (x _k, y _k, z _k, ax _k, ay _k, az _z);

(6) the corresponding point p on triangular topological relations _kNumber n 〉=4, with sextuple point set { l _kBe data point, and be step-length structure chord length parametric spline curve with d, obtain sextuple point set { m _k(x _k, y _k, z _k, ax _k, ay _k, az _k), as a trajectory;

When 0＜n≤3, industrial computer is with { m _k}={ l _k(k=1,2,3) as a track;

Work as n=0, industrial computer finishes computing;

(7) with the above-mentioned trajectory { m that obtains _kBe with reference to trajectory, it is projected on the x-y plane, and to obtain with it on the x-y plane be d (x along the axial distance of x _K+1=x _k+ d) point set then, obtains the respective point q on the triangular topological relations _k(x _k, y _k, z _k); And with point set { q _kProject on the x-y plane after, get successively a little until minimum rectangular area (x with step-length d along the y direction of principal axis _Min, y _Min), (x _Max, y _Max) the border, then, calculate the point set of each point on triangular topological relations that extend line segment q ' _k, again with { q _kAnd q ' _kMerge the point set { p obtain on the triangular topological relations _k(x _k, y _k, z _k);

(8) repeat above-mentioned steps (5)-(7) and obtain next bar trajectory, up to x _K+1＞x _MaxThe time, industrial computer finishes computing;

(9) the sextuple track data that will be obtained by industrial computer outputs to the robot switch board, and the laser instrument processing head on the control robot is processed this free form surface.

For trajectory planning along any direction, can by with this direction coordinate transform to the x-y coordinate direction, in the x-y coordinate system, generate again behind the track through inverse transformation and obtain trajectory planning along any direction.

The described triangle Bernstein-B of above-mentioned steps (5) é zier curved surface is three triangle Bernstein-B é zier curved surfaces.

Advantage of the present invention: method of carrying out path planning based on the 3 d discrete point collection data of free form surface of the present invention, utilize triangle Bernstein-B é zier curved surface, realized 3 d discrete point collection data free form surface match arbitrarily and the sextuple machining locus planning on interpolation curved surface, thereby can carry out path planning any free form surface.

Description of drawings

Fig. 1 is the schematic flow sheet of method of the path planning of 3 d discrete point collection data of the present invention

Fig. 2 utilizes triangle Bernstein-B é zier curved surface interpolation curved surface to be carried out the schematic flow sheet of trajectory planning

Fig. 3 is a kind of laser-processing system synoptic diagram of the embodiment of the invention

Fig. 4 is the Laser Processing track of automobile die of the present invention subregion

Fig. 5 is the actual processing effect of automobile die of the present invention

Accompanying drawing indicates

1, laser instrument 2, industrial computer 3, multi-shaft interlocked frame-type robot

4, laser Machining head

Embodiment

Be described in detail specific embodiments of the present invention with reference to accompanying drawing 1-3.

The Laser Processing control system that present embodiment adopted be Chinese Academy of Sciences's mechanics the patent No. be 98101217.5 a kind ofly have flexible transmission and multi-shaft interlocked laser processing device carries out, as shown in Figure 3, laser Machining head 4 is fixedlyed connected with frame-type robot 3 arms, link to each other with optical fiber between the output terminal of laser instrument 1 and the laser Machining head 4, the input end of laser instrument 1 is connected with industrial computer 2 by fieldbus, frame-type robot 3 is a high precision, five robots on a large scale, the switch board of this frame-type robot 3 also is connected with industrial computer 2 by serial ports, this example adopts 500W YAG pulsed laser 1 (peak power can reach 7KW) that automobile die is carried out surface peening, this laser parameter: pulsewidth 24ms, pulse recurrence rate 4Hz; Its detailed process is as follows:

1, as shown in Figure 1, industrial computer 2 is after receiving the 3 d discrete point collection data of automobile die, by three-dimensional data projection domain subdivision method 3 d discrete point collection data are carried out triangulation, obtain the triangulation grid of three-dimensional space data point, the summit of triangulation grid is P ₁, P ₂..., obtain point set { P _i, then, calculate summit P by following formula _iNormal vector and tangent vector:

$N_{\mathrm{ik}}=\frac{(P_{\mathrm{ik}}-P_i)\×(P_{i(k+1)}-P_i)}{|(P_{\mathrm{ik}}-P_i)\×(P_{i(k+1)}-P_i)|}---\left(1\right)$

S _ik＝|(P _ik-P _i)×(P _i(k+1)-P ₀)|/2 (2)

$N\left(P_i\right)=\underset{k=1}{\overset{m}{\mathrm{\Σ}}}{N}_{\mathrm{ik}}{S}_{\mathrm{ik}}/\underset{k=1}{\overset{m}{\mathrm{\Σ}}}{S}_{\mathrm{ik}}---\left(3\right)$

$\left\{\begin{array}{c}{D}_{i,i+1}=(P_{i+1}-P_i)-\left[(P_{i+1}-P_i){\·n}_i\right]n_i\\ D_{i,i+2}=(P_{i+2}-P_i)-\left[(P_{i+2}-P_i){\·n}_i\right]n_i\end{array}\right.---\left(4\right)$

In the formula, m is and P _iAdjacent triangle number, P _Ik, P _{I (k+1)}For with P _iK adjacent vertex of a triangle, N _IkFor with P _iAdjacent k leg-of-mutton normal vector, S _IkWith P _iAdjacent k leg-of-mutton area obtains the normal vector N (P on each summit _i) and tangent vector D _{I, i+1}, D _{I, i+2}

At last, utilize the normal vector N (P on each summit _i) and tangent vector D _{I, i+1}, D _{I, i+2}Each triangle is carried out triangle Bernstein-B é zier structure three times, obtain the cubic interpolation curved surface of 3 d discrete point collection data, obtain the space triangular topological relations;

2, as shown in Figure 2, by industrial computer 2 track that further planning robot carries out Laser Processing on triangle Bernstein-B é zier curved surface, concrete steps are as follows:

(1) the space triangular topological relations that step 1 is obtained projects on the x-y plane, and determines the minimum rectangular area (x that comprises curved surface projection on the x-y plane _Min, y _Min), (x _Max, y _Max);

(2) the instruction industrial computer is with p ' ₁=(x _Min, y _Min) be starting point, every interval d=1.26mm gets a p ' successively along the y direction of principal axis _k=(x _Min, y _Min+ (k-1) * d), up to border terminal point (x _Min, y _Max), d is the interval between the two processing stand centers here, again according to p ' _kCorresponding point P on triangular topological relations _k(k=1,2 ..., n)=(x _k, y _k, z _k);

(3) obtain p according to following computing formula _kCenter of gravity parameter in the corresponding triangular domain (u, v, w):

p _k＝ua+vb+wc

u+v+w＝1

A, b, c are and a p in the formula _kThree apex coordinates of corresponding triangular domain.

(4) again according to { p _k(u, v w), obtain sextuple point set { l on the corresponding triangular surface in conjunction with the triangle Bernstein-B é zier curved surface of institute's match for each point that point is concentrated and the center of gravity parameter in the corresponding triangular domain thereof _k}={ (x _k, y _k, z _k, ax _k, ay _k, az _z);

(5) the corresponding point p on triangular topological relations _kNumber n 〉=4, with sextuple point set { l _kBe data point, be step-length structure chord length parametric spline curve with d, obtain sextuple point set { m as article one trajectory _k(x _k, y _k, z _k, ax _k, ay _k, az _k);

Corresponding point p on triangular topological relations _kNumber 0＜n≤3, then with { m _k}={ l _k, (k=1,2,3) are as article one track;

Corresponding point p on triangular topological relations _kNumber n=0, industrial computer finishes computing;

(6) with the above-mentioned trajectory { m that obtains _kBe with reference to trajectory, it is projected on the x-y plane, and to obtain with it on the x-y plane be d (x along the axial distance of x _K+1=x _k+ d) point set then, obtains the respective point q on the triangular topological relations _k(x _k, y _k, z _k); And with point set { q _kProject on the x-y plane after, get successively a little until minimum rectangular area (x with step-length d along the y direction of principal axis _Min, y _Min), (x _Max, y _Max) the border, then, calculate the point set of each point on triangular topological relations that extend line segment q ' _k, again with { q _kAnd q ' _kMerge the point set { p obtain on the triangular topological relations _k(x _k, y _k, z _k);

(7) repeat above-mentioned steps (3)-(6) and obtain next bar trajectory, up to x _K+1＞x _MaxThe time, industrial computer finishes computing.

3, industrial computer 2 will obtain the trajectory data-switching and become the robot motion to instruct, output to the switch board of robot 3 again by the serial ports of industrial computer 2, according to the trajectory data of planning automobile die is processed by robot switch board control laser Machining head 4.

The result of the laser surface machining path of automobile die subregion planning as shown in Figure 4, the effect after the Laser Processing is as shown in Figure 5.

Claims (3)

1, a kind of method of carrying out path planning based on the 3 d discrete point collection data of free form surface, this method is in the Laser Surface Treatment system, obtain sextuple track data by the industrial computer processing and output to robot, and control robot drives the laser instrument processing head be fixed on its arm and moves according to sextuple track data, and its step comprises:

(1) after industrial computer receives the 3 d discrete point collection data of free form surface, utilizes triangle Bernstein-B é zier curved surface to carry out the interpolation curved surface that match obtains 3 d discrete point collection data, obtain the space triangular topological relations;

(2) this space triangular topological relations is projected to the xy plane, get on the triangular topological relations of space (x, the y) coordinate, and determine rectangular area (x that point is concentrated every bit with this by industrial computer _Min, y _Min), (x _Max, y _Max);

(3) with a p ₁'=(x _Min, y _Min) be starting point, get a formation point set { p successively along the y direction of principal axis _k', p _k'=(x _Min, y _Min+ (k-1) * d), (k=1,2 ..., n), wherein, d is the distance between two points that requirement is determined according to difference, until point (x _Min, y _Max); According to the resulting space of step (1) triangular topological relations, obtain p again _k' corresponding point p on triangular topological relations _k(x _k, y _k, z _k), form point set { p _k;

(4) according to { p _kEach point of concentrating of point and calculate with { p _k(u, v w), utilize triangle Bernstein-B é zier curved surface to calculate sextuple point set { l on the corresponding triangular surface for center of gravity parameter in the corresponding triangular domain of point set _k}={ (x _k, y _k, z _k, ax _k, ay _k, az _z);

(5) the corresponding point p on triangular topological relations _kNumber n 〉=4, with sextuple point set { l _kBe data point, and be step-length structure chord length parametric spline curve with d, obtain sextuple point set { m _k(x _k, y _k, z _k, ax _k, ay _k, az _k), as a trajectory;

When 0＜n≤3, industrial computer is with { m _k}={ l _k, (k=1,2,3) are as a track;

Work as n=0, industrial computer finishes computing;

(6) with the above-mentioned trajectory { m that obtains _kBe with reference to trajectory, it is projected on the x-y plane, and to obtain with it on the x-y plane be d (x along the axial distance of x _K+1=x _k+ d) point set then, obtains the respective point q on the triangular topological relations _k(x _k, y _k, z _k); And with point set { q _kProject on the x-y plane after, get successively a little until minimum rectangular area (x with step-length d along the y direction of principal axis _Min, y _Min), (x _Max, y _Max) the border, then, calculate the point set { q of each point on triangular topological relations that extends line segment _k', again with { q _kAnd { q _k' merge the point set { p obtain on the triangular topological relations _k(x _k, y _k, z _k);

(7) repeat above-mentioned steps (5)-(6) and obtain next bar trajectory, up to x _K+1＞x _MaxThe time, industrial computer finishes computing;

(8) the sextuple track data that will be obtained by industrial computer outputs to the robot switch board, and the laser instrument processing head on the control robot is processed this free form surface.

2, by the described method of carrying out path planning based on the 3 d discrete point collection data of free form surface of claim 1, it is characterized in that, for trajectory planning along any direction, can by with this direction coordinate transform to the x-y coordinate direction, in the x-y coordinate system, generate again behind the track through inverse transformation and obtain trajectory planning along any direction.

3, carry out the method for path planning by claim 1 is described based on the 3 d discrete point collection data of free form surface, it is characterized in that the described triangle Bernstein-B of step (4) é zier curved surface is three triangle Bernstein-B é zier curved surfaces.

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