CN108253911B - A kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration - Google Patents

Abstract

The invention discloses a kind of workpiece pose methods of adjustment based on measurement point geometrical characteristic iteration registration, comprising the following steps: unified measurement coordinate system and workpiece coordinate system, detection workpiece obtain contact measurement data；The machining deviation and overproof amount OT of measurement point are calculated according to contact measurement data；If the OT of measurement point is not zero, it is transferred to step 4, is otherwise terminated；Overproof curved surface is selected, surface rotary registration matrix and surface translation registration matrix are obtained, is coupled it in workpiece rotation registration matrix and workpiece translational motion registration matrix respectively；The adjustment amount of workpiece coordinate system is calculated according to the topological structure of specified lathe and workpiece rotation registration matrix；Workpiece positioning is readjusted according to the workpiece coordinate system of specified lathe；Workpiece coordinate system is adjusted according to adjustment amount, detection workpiece obtains contact measurement data, continues to adjust to meeting the requirements；The invention is simple and feasible, and the processing pose that can meet under the multiple features multi-constraint condition of process part processing quickly adjusts.

Description

A kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration

Technical field

The present invention relates to Computerized Numerical Control processing technology fields, and in particular to a kind of work based on measurement point geometrical characteristic iteration registration Part pose method of adjustment.

Background technique

Complex parts Precision Machining is usually directed to a series of process, since Workpiece's Tack Error, distortion inaccuracy, lathe are several The presence of what error and other error components, may cause per pass operation allowance and is unevenly distributed, or even overproof (OT) occurs；Cause This is highly desirable using such as On-machine Test system, contact type scanning system, non-contact 3-D scanning system, measurement of coordinates The precise detection technologies such as machine (CMM) and measurement of coordinates arm (CMR) and instrument detect the geometric profile between workpiece process；More In process processing, for the allowance balance homogenizing or error compensation of subsequent handling, the positioning of adjustment workpiece is mostly used greatly, by adaptive It answers fixture to relocate workpiece and the methods of regenerate numerical control (NC) program to realize；In this regard, the invention proposes based on measurement The workpiece pose method of adjustment of point geometry feature iteration registration, this method are registrated by workpiece and realize Machinetool workpiece coordinate system again Definition, and then realize the repositioning of workpiece；The opposite above method, this method are more simple and easy to do.

For non-contact detection, registration Algorithm is concentrated mainly on a cloud and CAD model；Point set registration (PSR) is meter Calculation makes a little spatial alternation process to best alignment；Most popular classics PSR algorithm is nearest by the iteration of Besl proposition Point (ICP) algorithm (Maiseli B, Gu Y, Gao H.Recent developments and trends in point set registration methods[J].Journal of Visual Communication and Image Representation,2017,46:95-106；Besl PJ,McKay ND.Method for registration of 3-d shapes,in:Robotics-DL Tentative[J].International Society for Optics and Photonics, 1992:586-606.), the algorithm be usually used in being registrated of free curve and curved surface (Sharp GC, Lee SW, Wehe DK.ICP registration using invariantfeatures[J].IEEE Transactions on Pattern Analysis and Machine Intelligence,2002,24(1):90-102；Li ZX,Gou JB,Chu YX.Geometric algorithms forworkpiece localization[J].IEEE Trans Robot Autom, 1998,14(6):864-878；Zhenhua X,Zexiang L.On the discrete symmetriclocalization problem[J].International Journal of Machine Tools and Manufacture,2003,43(9): 863-870；Chatelain JF,Fortin C.A balancing technique for optimalblank part machining[J].PrecisionEngineering,2001,25(1):13-23.)；For complex parts, Zhu (Zhu LM, Xiong ZH,DingH,et al.A distance function based approach for localization and profile error evaluation of complex surface[J].Journal of Manufacturing Science and Engineering, 2004,126 (3): 542-54.) etc. propose complicated curved rigid surfaces optimal registration calculate Method, Sun (Sun YW, Xu JT, Guo DM, et al.A unified localization approach for machining allowance optimization of complex curved surfaces[J].Precision Engineering, 2009,33 (4): 516-23.) a kind of develop unification large-scale curved location technology, meet user's definition Need preferentially guarantee machining allowance particular surface constraint；In practical applications, due to the difference of allowance balance, PSR algorithm It may result in constraint condition conflict, and possibly can not obtain optimal solution (Ying Z, Dinghua Z, Baohai W.An approach for machining allowance optimization of complex parts with integrated structure[J].Journal ofComputationalDesignandEngineering,2015,(2): 248-252.)。

Since the registration under non-contact detection is difficult to establish the mapping relations on specific point-surface, this calculates PSR Method is only registrated effective (Zhang DH, Zhang Y, Wu BH.Research on the adaptive in advance to curved surface machining technology of blisk[J].Advanced Materials Research,2009,69-70:446- 50；Evgeny L,Dmitry C,Aniko E.Pre-registration of arbitrarily oriented 3D surfaces usinga genetic algorithm[J].Pattern Recognition Letters,2006,27(11): 1201-1208；Sun YW,Wang XM,Guo DM,Liu Jian.Machining localization and quality evaluation of partswith sculptured surfaces using SQP method[J].International Journal of Advanced Manufacturing Technology,2009,(42):1131-1139；Tan GS,Zhang LY,Liu SL,YeN.an An unconstrained approach to blank localization with allowanceassurance for machining complex parts[J].International Journal of Advanced Manufacturing Technology,2014,(73):647-658.)；In contrast, contact detection can obtain More relation informations of measured surface are obtained, for example, having the theoretical test point and actually detected point pair for determining detection direction；Measurement Point set, tolerance and respective surfaces with determining mapping relations etc.；In addition, workpiece coordinate system (WCS) and detection coordinate system (ICS) be also easier unification, therefore accurate surplus and error distributed intelligence can be obtained, with improve have complex outline and The workpiece of more tolerance constraints is registrated.

In the case where contacting detection, some researchers are modeled as the registration to have constrained Least-squares minimization and ask Topic；Sijie(Sijie Y,Yunfei Z,Fangyu P,XideL.Research on the localisation of the workpieces with large sculpturedsurfaces in NC machining[J].International Journal of Advanced Manufacturing Technology, 2004,23:429-435.) using genetic algorithm with Simplex method (GAs) solves the registration problems of large complicated carved class blank；Dai(Dai YF,Chen SY,Kang NH, Li SY(2010)Error calculation for corrective machining with allowance requirements.Int J AdvManufTechnol 49:635–641.)⁰Propose alternate optimization method and continuously linear The hybrid optimization algorithm of change method；In terms of numerical stability, efficiency and accuracy, constrained optimization be difficult to solve (Tan GS, Zhang LY,Liu SL,YeN.an An unconstrained approach to blank localization with allowanceassurance for machining complex parts[J].International Journal of Advanced Manufacturing Technology,2014,(73):647-658.)；Chatelain(Chatelain JF.A level-based optimization algorithm for complexpart localization[J] .PrecisEng,2005,29(2):197-207.)⁰With Tan (Tan GS, Zhang LY, Liu SL, YeN.an An unconstrained approach to blank localization with allowanceassurance for machining complex parts[J].International Journal of Advanced Manufacturing Technology, 2014, (73): 647-658.) registration problems are attributed to for min-max problem, such binding occurrence is just It is difficult to suitably distribute；Ying(Ying Z,Dinghua Z,Baohai W.An approach for machining allowance optimization of complex parts with integrated structure[J].Journal Of Computational Design and Engineering, 2015, (2): 248-252.) it establishes based on contactless The machining allowance Optimized model of detection, still, which is only applicable to the blank of symmetrical leaf dish；On the other hand, mostly existing A tolerance constraints can only be arranged in method on entire workpiece.

In addition, due to gauge head size, the influence of detection direction predetermined and curvature of curved surface, actual spot of measurement and theory There is no point-device spatial relationship between measurement point, so registration cannot be directly by actual initial measurement point and corresponding reason It is realized by measurement point；Currently, adaptive iteration registration and alignment adjusting method under more more or less terms based on contact type measurement Correlative study it is less.

Summary of the invention

The present invention, which provides one kind, can meet changing under the multiple features multi-constraint condition of process part processing based on measurement point geometrical characteristic The workpiece pose method of adjustment of generation registration.

The technical solution adopted by the present invention is that: a kind of workpiece pose adjustment side based on measurement point geometrical characteristic iteration registration Method, comprising the following steps:

Step 1: unified measurement coordinate system and workpiece coordinate system, detection workpiece obtain contact measurement data；

Step 2: the machining deviation and overproof amount OT of measurement point are calculated according to contact measurement data；

Step 3: if the OT of measurement point is not zero, being transferred to step 4, otherwise terminate；

Step 4: selecting overproof surface, surface rotary registration matrix and surface translation registration matrix are obtained, respectively by its coupling It closes in workpiece rotation registration matrix and workpiece translational motion registration matrix；

Step 5: the adjustment amount of workpiece coordinate system is calculated according to the topological structure of specified lathe and workpiece rotation registration matrix；

Step 6: workpiece positioning is readjusted according to the workpiece coordinate system of specified lathe；

Step 7: workpiece coordinate system being adjusted according to the adjustment amount that step 5 obtains, detection workpiece obtains contact measurement data, turns Enter step 2.

Further, the contact measurement data include with determine detection direction theory and actual spot of measurement coordinate, Detect the measurement direction vector and tolerance on surface.

Further, the calculation method of machining deviation and overproof amount OT are as follows in the step 2:

S1: the theoretical coordinate of m-th of measurement point on n-th of face is set as P_{n_m}(x_{n_m},y_{n_m},z_{n_m}), actual coordinate is P '_{n_m} (x′_{n_m},y′_{n_m},z′_{n_m}), measurement direction d_{n_m}(i_{n_m},j_{n_m},k_{n_m}), machining deviation are as follows:

S2: define n-th of surface on upper and lower deviation be respectivelyWithObtained after decomposition upper and lower deviation in X, Y and Component in Z-direction

S3: the overproof amount of each measurement point in the x, y, and z directions is as follows:

Further, surface rotary registration matrix computational approach is as follows in the step 4:

If S_nFor vector v '_nWith v_nThe method arrow of constituted plane, θ_nFor v '_nWith v_nAngle:

S_n=v '_n×v_n=(i_n-S j_n-S k_n-S 0)^T (4)

Wherein v '_nFor actual surface characteristic vector, v_nFor theoretical surface characteristic vector；θ_n=arccos (v_n·v′_n)；

Then surface rotary registration matrix R_nAre as follows:

In formula:

Further, in the step 4 that surface rotary registration Matrix coupling is as follows to workpiece rotation registration matrix method:

Z axis is defined as reference direction, actual surface characteristic vector v '_nZ axis and surface rotary registration matrix R can be passed through_n Transformation:

Workpiece actual characteristic vector v ' are as follows:

In formula: N is measurement characteristic face sum；

Workpiece rotation is registrated matrix R and is calculated according to actual characteristic vector v ' and theory characteristic vector v by formula (5).

Further, the calculation method of surface translation registration matrix is as follows in the step 4:

Homogeneous coordinates and homogeneous transform matrix are used in calculating process, translation matrix is indicated by HTMT, and spin matrix is used HTMR indicates that the transformation of the measurement point and characteristic vector of n-th of curved surface is expressed as:

In formula:For the measurement point coordinate after rotary registration；

To rotate and translating the measurement point coordinate after being registrated；

P′_{n_m}=(x '_{n_m} y′_{n_m} z′_{n_m} 1)^TFor initial actual spot of measurement coordinate；

T is that workpiece translational motion is registrated matrix；

The translation on n-th of surface is registrated vector u_n:

In formula: M is measurement point quantity.

Further, surface translation is registrated Matrix coupling in the step 4 and is registrated the method for matrix such as to workpiece translational motion Under:

In formula: u is that workpiece translational motion is registrated matrix, Δ x, Δ y, and Δ z is average registration of the workpiece on tri- directions X/Y/Z Distance.

Further, the surface characteristics vector includes that planar process is sweared, the comprehensive of the axis resultant free form surface on cylindrical surface is sweared Amount；

S11: planar process swears that calculating process is as follows:

If the equation of n-th of theoretical measurement plane is a_nx+b_ny+c_nz+d_n=0, then theoretical planes per unit system swears v1_nAre as follows:

In the theoretical measurement point set P of n-th of theoretical measurement plane_n={ P_{n_m}| m=1 ..., M in arbitrarily choose three points P₁(x_{n_1}, y_{n_1}, z_{n_1})、P₂(x_{n_2}, y_{n_2}, z_{n_2}) and P₃(x_{n_3}, y_{n_3}, z_{n_3}), wherein M is total measurement point number；Under Formula obtains parameter a_n、b_nAnd c_nAnd d_n；

Theoretical planes per unit system arrow v1 is obtained according to formula (13) and formula (12)_n；

For n-th of actual measurement plane, per unit system swears v1 '_nIt is obtained by fitting, fit Plane equation are as follows:

a′_nx+b′_ny+c′_nz+d′_n=0 (14)

In formula: a '_n、b′_n、c′_nWith d '_nFor parameter；

The measurement point set P ' of n-th of actual measurement plane_n={ P '_{n_m}| m=1 ..., M }, building such as minor function:

It enablesIt obtains:

Solution formula (16) is up to parameter a '_n、b′_n、c′_n；Substituting into following formula can be obtained the per unit system arrow of physical plane:

S12: the axis arrow calculating process on cylindrical surface is as follows:

The unit axis arrow on n-th of theoretical cylindrical surface is defined as v2_n=(i_n j_n k_n0), radius R_n, P_{n_k}For axis Upper certain point, α_{n_m}For axis and P_{n_k}P_{n_m}Between angle, P_{n_m}Distance to axis is R_{n_m}；

In formula:P_{n_k}Coordinate be

R_{n_m}With R_nBetween error be expressed as:

Wherein:

It solvesIts result minimum is set to can be obtained parameter i_n, j_n, k_n, theoretical cylindrical axes arrow can be obtained, wherein e_n =(e_{n_1} ... e_{n_M})；

V2 ' is sweared according to the axis that n-th of practical cylinder can be obtained in the above method_n；

S13: curve surface comprehensive vector calculating process is as follows:

According to measurement point P_{n_k}And P_{n_m}Calculate vector v_{m_k}:

v_{1_k}With other v_{m_k}Between vertical vector v_{n_m_k}Are as follows:

The synthetic vector v3 of n-th of theoretical curved surface_nAre as follows:

The synthetic vector v3 ' of corresponding n-th of practical curved surface can be acquired using the above method_n。

The beneficial effects of the present invention are:

(1) the processing pose that the present invention can meet under the multiple features multi-constraint condition of process part processing quickly adjusts；

(2) present invention is registrated by workpiece realizes that Machinetool workpiece coordinate system redefines, and then realizes the again fixed of workpiece Position, it is more simple and easy to do；

(3) the unified workpiece coordinate system of the present invention and detection coordinate system, obtain accurate surplus and error distributed intelligence, improve It is registrated with the workpiece of complex outline and more tolerance constraints.

Detailed description of the invention

Fig. 1 is flow diagram of the present invention.

Fig. 2 is workpiece physical location and theoretical position relation schematic diagram.

Fig. 3 is machining deviation and tolerance relation schematic diagram.

Fig. 4 is planar process arrow and measurement point schematic diagram.

Fig. 5 is axis arrow and cylinder measurement point schematic diagram.

Fig. 6 is free-float space robot point and synthetic vector schematic diagram.

Fig. 7 is the rotation schematic diagram of surface characteristics vector.

Fig. 8 is the practical conversion vector schematic diagram based on Z axis.

Fig. 9 is test block model schematic in embodiment.

Specific embodiment

The present invention will be further described in the following with reference to the drawings and specific embodiments.

As shown in Figure 1, the present invention analyzes in theoretical and actual contact measurement data basis with different tolerances The mismachining tolerance of curved surface, a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration of proposition, including with Lower step:

Step 1: unified measurement coordinate system and workpiece coordinate system, detection workpiece obtain contact measurement data；Contact measurement number According to the measurement direction vector and tolerance for including theory and actual spot of measurement coordinate, detection surface with determining detection direction.

Step 2: the machining deviation and overproof amount OT of measurement point are calculated according to contact measurement data；

According to machining tolerance and continual curvature, workpiece profile can be divided into cylindrical surface, plane and free form surface；For each Surface, can be by contact measurement data analysis deviation and OT；

In the detection process, measurement coordinate system is set by workpiece coordinate system WCS, if m-th measurement point on n-th of face Theoretical coordinate is P_{n_m}(x_{n_m},y_{n_m},z_{n_m}), actual coordinate is P '_{n_m}(x′_{n_m},y′_{n_m},z′_{n_m}), measurement direction d_{n_m}(i_{n_m}, j_{n_m},k_{n_m}), according to the definition for cutting and owing to cut excessively, machining deviation are as follows:

The upper and lower deviation defined on n-th of surface is respectivelyWithUpper and lower deviation is obtained after decomposition in X, Y and the side Z Upward component

Therefore, the overproof amount of each measurement point in the x, y, and z directions are as follows:

Step 3: if the OT of measurement point is not zero, being transferred to step 4, otherwise terminate；If any one measurement point Overproof amount be not zero, then it represents that in process in front, finished surface occurred cutting or owe the case where cutting, then subsequent Mismachining tolerance compensation is carried out in processing to be very important.

Step 4: selecting overproof curved surface, surface rotary registration matrix and surface translation registration matrix are obtained, respectively by its coupling It closes in workpiece rotation registration matrix and workpiece translational motion registration matrix.

According to kinematic principle, workpiece has six-freedom degree (around X, Y and three rotation amounts of Z axis and three translational movements)； The position of workpiece can be changed due to rotating, rotary registration should carry out before translation；In order to simplify registration, in calculating Using homogeneous coordinates and homogeneous transform matrix (HTM), then translation matrix can be indicated by HTMT, and spin matrix can use HTMR Indicate (Jiang L, Ding GF, Li Z, Zhu SW and Qin SF.Geometric error model and measuring method based on worktable for five axis machine tools[J].Journal of Engineering Manufacture,2013,227(1):32-44.)；The measurement point of n-th curved surface and the transformation of characteristic vector It can indicate are as follows:

In formula:For the measurement point coordinate after rotary registration；

To rotate and translating the measurement point coordinate after being registrated；

P′_{n_m}=(x '_{n_m} y′_{n_m} z′_{n_m} 1)^TFor initial actual spot of measurement coordinate；

The translation on n-th of surface is registrated vector u_n:

In formula: M is measurement point quantity.

Different characteristic face is not unified due to the description method of geometric parameter and characteristic vector, the difference of processing franchise Method for registering；It needs first to carry out the registration of each characteristic face respectively, then couples the registration matrix of formation process part.

Characteristic vector is characterized the unique definition in face direction, and for convenience of calculation, the present invention is by the method arrow of plane, cylindrical surface Axis arrow, free form surface characteristic vector of the synthetic vector as characteristic face.

(1) planar process arrow calculates

If the equation of n-th of theoretical measurement plane is a_nx+b_ny+c_nz+d_n=0, then theoretical planes per unit system swears v1_nAre as follows:

In the theoretical measurement point set P of n-th of theoretical measurement plane_n={ P_{n_m}| m=1 ..., M in arbitrarily choose three points P₁(x_{n_1}, y_{n_1}, z_{n_1})、P₂(x_{n_2}, y_{n_2}, z_{n_2}) and P₃(x_{n_3}, y_{n_3}, z_{n_3}), wherein M is total measurement point number；Under Formula obtains parameter a_n、b_nAnd c_n；

Theoretical planes per unit system arrow v1 is obtained according to formula (13) and formula (12)_n；

For n-th of actual measurement plane, per unit system swears v1 '_nIt is obtained by fitting, fit Plane equation are as follows:

a′_nx+b′_ny+c′_nz+d′_n=0 (14)

The measurement point set P ' of n-th of actual measurement plane_n={ P '_{n_m}| m=1 ..., M }, according to principle of least square structure It builds such as minor function:

It enablesIt obtains:

Solution formula (16) is up to parameter a '_n、b′_n、c′_n；Substituting into following formula can be obtained the per unit system arrow of physical plane:

In order to ensure the precision of fit Plane, the quantity of the point for fitting is no less than 3, and guarantees that at least there are three survey Amount point is not conllinear.

(2) cylindrical axes arrow calculates

The axis arrow on theoretical cylindrical surface can be solved by cylindrical surface fitting, and it is fixed that the unit axis on n-th of theoretical cylindrical surface is sweared Justice is v2_n=(i_n j_n k_n0), radius R_n, P_{n_k}For certain point on axis, α_{n_m}For axis and P_{n_k}P_{n_m}Between angle, P_{n_m}Distance to axis is R_{n_m}；

In formula:P_{n_k}Coordinate be

R_{n_m}With R_nBetween error be expressed as:

Wherein:

According to the principle of least square, solveIts result minimum is set to can be obtained parameter i_n, j_n, k_n, theory can be obtained Cylindrical axes swear v_n, wherein e_n=(e_{n_1} ... e_{n_M})；

According to identical method and corresponding point set, the axis arrow v2 ' of n-th of practical cylinder can be obtained_n；In order to improve column Face fitting precision, cylinder measurement point should be distributed circumferentially as far as possible, and it must not count less than three.

(3) curve surface comprehensive vector

In order to explicitly define the direction of free form surface by contact measurement data, the comprehensive of curved surface can be defined according to measurement point Resultant vector；As shown in figure 5, selection measurement point P_{n_k}, P can be passed through_{n_k}With other measurement points P_{n_m}Calculate vector v_{m_k}:

v_{1_k}With other v_{m_k}Between vertical vector v_{n_m_k}Are as follows:

The synthetic vector v3 of n-th of theoretical curved surface_nAre as follows:

The synthetic vector v3 ' of corresponding n-th of practical curved surface can be acquired using the above method_n。

Surface rotary registration matrix computational approach is as follows:

If S_nFor vector v '_nWith v_nThe method arrow of constituted plane, θ_nFor v '_nWith v_nAngle:

S_n=v '_n×v_n=(i_n-S j_n-S k_n-S 0)^T (4)

Wherein v '_nFor actual surface characteristic vector, v_nFor theoretical surface characteristic vector；θ_n=arccos (v_n·v′_n)；

Then surface rotary registration matrix R_nAre as follows:

In formula:

In the registration matrix R for acquiring each measurement surface_nLater, it is coupled in workpiece rotation registration matrix；But It is due to ununified reference direction, R_nIt cannot directly add up；In the present invention, Z axis is newly defined as reference direction, therefore Actual characteristic vector v '_nZ axis and R can be passed through_nIt is transformed to vector:

Workpiece actual characteristic vector v ' are as follows:

The vector is the accumulation of all surface actual characteristic transformation vector, in formula: N is measurement characteristic face sum；

Workpiece rotation is registrated matrix R and is calculated according to actual characteristic vector v ' and theory characteristic vector v by formula (5).

According to formula (8) to practical with after theoretical measurement point progress rotary registration, the translation on n-th of surface is registrated vector are as follows:

Obtain the translation registration vector u on each surface_nAfterwards, being added up and being averaged to it can be obtained workpiece translational motion and matches Quasi- matrix u:

In formula: u is that workpiece translational motion is registrated matrix, Δ x, Δ y, and Δ z is average registration of the workpiece on tri- directions X/Y/Z Distance；

Workpiece translational motion registration matrix can be indicated with T:

Step 5: the adjustment amount of workpiece coordinate system is calculated according to the topological structure of specified lathe and workpiece rotation registration matrix； The adjustment of workpiece coordinate system WCS can redefine function by the WCS of five-axis machine tool to realize；New WCS coordinate origin can It is realized by the translation of Serial regulation amount the Δ x, Δ y, Δ z of X, Y and Z axis of lathe；Its direction passes through rotary axis of machine tool Rotation can obtain；By taking the five-axle number control machine tool of CZFXYB (workbench main shaft dual AC power) structure as an example, the Z axis of new WCS and ZOX coordinate plane can be defined by C and the rotation angle Δ C and Δ B of B axle, then had:

Step 6: workpiece positioning is readjusted according to the workpiece coordinate system of specified lathe；

Step 7: workpiece coordinate system being adjusted according to the adjustment amount that step 5 obtains, detection workpiece obtains contact measurement data, turns Enter step 2.

In the Precision Machining of complex parts, workpiece needs that production process could be completed by multiple working procedure, process part processing Machining accuracy and allowance distribution influence the processing quality of subsequent handling very big；In order to realize process part processing processing by pose adjustment The control of precision and surplus, the present invention propose that three coordinate On-machine Test data carry out the pose adjustment of workpiece adaptive iteration registration With localization method to realize the adaptive adjustment of workpiece posture and be accurately positioned.

Below with ISO five-axle number control machine tool typical process test block (ISO CD 10791-7:2017, Test Conditions for machining centres-Part 7:Accuracy of finished test piece) conduct Machining posture method of adjustment verifies example, and characteristic face includes a plane, two hole cylinders and two ruled surfaces；Wherein plane Franchise up and down be ± 0.1mm, hole cylinder franchise be ± 0.25mm, ruled surface franchise be ± 0.05mm, each surface measurement point Quantity be 5,10 and 22 respectively；WCS is arranged in a certain angle point of plane, as shown in Figure 9；Machine model DMG DMU 100T has Renishaw On-machine Test system；Theoretical and practical initial measurement data is as shown in table 1, it is known that all test points Occur with measuring surface overproof.

1 initial measurement data of table (mm)

The registration and method of adjustment proposed through the invention, it is every all to reduce by once adjusting overproof amount, it is adjusted three times It is whole to make the overproof amount of all surface near 0；Workpiece is registrated matrix and correlated results is as shown in table 2.

Table 2 adjusts result and relevant reference value

The registration that the present invention first rotates according to process part processing measurement data and constraint condition, according to each characteristic face, is translatable afterwards is suitable Sequence, calculates the registration matrix of each characteristic face, and couples formation process part registration matrix；Further according to registration iterative algorithm, expired The optimal location and pose adjustment amount of the current process part of sufficient subsequent handling processing request；Pass through experimental test, the method for the present invention The processing pose that can satisfy under the multiple features multi-constraint condition of process part processing quickly adjusts.

Claims (7)

1. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration, which is characterized in that including following step It is rapid:

Step 1: unified measurement coordinate system and workpiece coordinate system, detection workpiece obtain contact measurement data；

Step 2: the machining deviation and overproof amount OT of measurement point are calculated according to contact measurement data；

Step 3: if the OT of measurement point is not zero, being transferred to step 4, otherwise terminate；

Step 4: selecting overproof curved surface, obtain surface rotary registration matrix and surface translation registration matrix, couple it to respectively Workpiece rotation is registrated in matrix and workpiece translational motion registration matrix；

Step 5: the adjustment amount of workpiece coordinate system is calculated according to the topological structure of specified lathe and workpiece rotation registration matrix；

Step 6: workpiece positioning is readjusted according to the workpiece coordinate system of specified lathe；

Step 7: workpiece coordinate system being adjusted according to the adjustment amount that step 5 obtains, detection workpiece obtains contact measurement data, is transferred to step Rapid 2；

The calculation method of machining deviation and overproof amount OT are as follows in the step 2:

S1: the theoretical coordinate of m-th of measurement point on n-th of face is set as P_{n_m}(x_{n_m},y_{n_m},z_{n_m}), actual coordinate is P '_{n_m} (x′_{n_m},y′_{n_m},z′_{n_m}), measurement direction d_{n_m}(i_{n_m},j_{n_m},k_{n_m}), machining deviation are as follows:

S2: define n-th of surface on upper and lower deviation be respectivelyWithUpper and lower deviation is obtained after decomposition in X, Y and Z-direction On component

S3: the overproof amount of each measurement point in the x, y, and z directions is as follows:

。

2. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 1, It is characterized in that, the contact measurement data include with the theory and actual spot of measurement coordinate for determining detection direction, detect surface Measurement direction vector and tolerance.

3. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 1, It is characterized in that, surface rotary registration matrix computational approach is as follows in the step 4:

If S_nFor vector v '_nWith v_nThe method arrow of constituted plane, θ_nFor v '_nWith v_nAngle:

S_n=v '_n×v_n=(i_n-S j_n-S k_n-S 0)^T

Wherein v '_nFor actual surface characteristic vector, v_nFor theoretical surface characteristic vector；θ_n=arccos (v_n·v′_n)；

Then surface rotary registration matrix R_nAre as follows:

In formula:

4. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 3, It is characterized in that, in the step 4 that surface rotary registration Matrix coupling is as follows to workpiece rotation registration matrix method:

Z axis is defined as reference direction, actual surface characteristic vector v '_nZ axis and surface rotary registration matrix R can be passed through_nBecome It changes:

Workpiece actual characteristic vector v ' are as follows:

In formula: N is measurement characteristic face sum；

Workpiece rotation is registrated matrix R and is calculated according to actual characteristic vector v ' and theory characteristic vector v by formula (5).

5. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 1, It is characterized in that, the calculation method of surface translation registration matrix is as follows in the step 4:

Homogeneous coordinates and homogeneous transform matrix are used in calculating process, translation matrix is indicated by HTMT, spin matrix HTMR It indicates, the transformation of the measurement point and characteristic vector of n-th of curved surface is expressed as:

In formula:For the measurement point coordinate after rotary registration；

To rotate and translating the measurement point coordinate after being registrated；

P′_{n_m}=(x '_{n_m} y′_{n_m} z′_{n_m} 1)^TFor initial actual spot of measurement coordinate；

T is that workpiece translational motion is registrated matrix；

The translation on n-th of surface is registrated vector u_n:

In formula: M is measurement point quantity.

6. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 5, It is characterized in that, the method that surface translation is registrated Matrix coupling to workpiece translational motion registration matrix in the step 4 is as follows:

In formula: u be workpiece translational motion be registrated matrix, Δ x, Δ y, Δ z be average registration of the workpiece on tri- directions X/Y/Z away from From.

7. a kind of workpiece pose method of adjustment based on measurement point geometrical characteristic iteration registration according to claim 3, Be characterized in that, the surface characteristics vector include planar process arrow, cylindrical surface axis resultant free form surface synthetic vector；

S11: planar process swears that calculating process is as follows:

If the equation of n-th of theoretical measurement plane is a_nx+b_ny+c_nz+d_n=0, then theoretical planes per unit system swears v1_nAre as follows:

In the theoretical measurement point set P of n-th of theoretical measurement plane_n={ P_{n_m}| m=1 ..., M in arbitrarily choose three point P₁ (x_{n_1}, y_{n_1}, z_{n_1})、P₂(x_{n_2}, y_{n_2}, z_{n_2}) and P₃(x_{n_3}, y_{n_3}, z_{n_3}), wherein M is total measurement point number；Pass through following formula Obtain parameter a_n、b_n、c_nAnd d_n；

Theoretical planes per unit system arrow v1 is obtained according to formula (13) and formula (12)_n；

For n-th of actual measurement plane, per unit system swears v1 '_nIt is obtained by fitting, fit Plane equation are as follows:

a′_nx+b′_ny+c′_nz+d′_n=0 (14)

In formula: a '_n、b′_n、c′_nWith d '_nFor parameter；

The measurement point set P ' of n-th of actual measurement plane_n={ P '_{n_m}| m=1 ..., M }, building such as minor function:

It enablesIt obtains:

Solution formula (16) is up to parameter a '_n、b′_n、c′_nWith d '_n；Substituting into following formula can be obtained the per unit system arrow of physical plane:

S12: the axis arrow calculating process on cylindrical surface is as follows:

The unit axis arrow on n-th of theoretical cylindrical surface is defined as v2_n=(i_n j_n k_n0), radius R_n, P_{n_k}For on axis certain A bit, α_{n_m}For axis and P_{n_k}P_{n_m}Between angle, P_{n_m}Distance to axis is R_{n_m}；

In formula:P_{n_k}Coordinate be

R_{n_m}With R_nBetween error be expressed as:

Wherein:

It solvesIts result minimum is set to can be obtained parameter i_n, j_n, k_n, theoretical cylindrical axes arrow can be obtained, wherein e_n= (e_{n_1}...e_{n_M})；

V2 ' is sweared according to the axis that n-th of practical cylinder can be obtained in the above method_n；

S13: curve surface comprehensive vector calculating process is as follows:

According to measurement point P_{n_k}And P_{n_m}Calculate vector v_{m_k}:

v_{1_k}With other v_{m_k}Between vertical vector v_{n_m_k}Are as follows:

The synthetic vector v3 of n-th of theoretical curved surface_nAre as follows:

The synthetic vector v3 ' of corresponding n-th of practical curved surface can be acquired using the above method_n。