CN110500969B - High-gradient complex curved surface in-situ measurement planning method - Google Patents
High-gradient complex curved surface in-situ measurement planning method Download PDFInfo
- Publication number
- CN110500969B CN110500969B CN201910947275.9A CN201910947275A CN110500969B CN 110500969 B CN110500969 B CN 110500969B CN 201910947275 A CN201910947275 A CN 201910947275A CN 110500969 B CN110500969 B CN 110500969B
- Authority
- CN
- China
- Prior art keywords
- curved surface
- complex curved
- gradient
- measurement
- scanning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention discloses an in-situ measurement planning method for a high-gradient complex curved surface, belongs to the field of curved surface measurement, and relates to the in-situ measurement planning method for the high-gradient complex curved surface. According to the method, an equi-illumination angle is used as a constraint condition to generate a complex curved surface non-equidistant transverse section contour line, a full-surface latticed scanning measurement path is obtained by combining the longitudinal section contour line, and a surface concave-convex characteristic is extracted according to average curvature changes in two parameter directions to generate a local encrypted scanning contour line. And then, according to the equal illumination angle and the obtained scanning path, performing multi-section splicing measurement motion planning to obtain a motion track of a sensor reference point. And finally, carrying out measurement deflection angle inspection on the optical measuring head to complete the on-site measurement planning of the complex curved surface. The method realizes the generation of the in-situ scanning path of the high-gradient complex curved surface and the planning of the measuring motion, ensures the measuring precision of the characteristic area, reduces the dynamic measuring error caused by the multi-axis linkage of the machine tool, and has the advantages of reliability and strong universality.
Description
Technical Field
The invention belongs to the field of curved surface measurement, and particularly relates to an in-situ measurement planning method for a high-gradient complex curved surface.
Background
In some high-end installations there is a large class of high-steepness complex free-form surfaces, the surfaces of which have relief features. The machining contour precision of the curved surface needs to be ensured according to the state obtained by in-situ precision measurement, and machining error compensation regulation and control are carried out. In the in-place measurement process, based on the movement of a machine tool, according to a planned scanning path, the non-contact high-precision displacement sensor is used for acquiring the surface data of the part, and further the geometric shape of the complex curved surface is reflected. Therefore, the reasonable planning of the scanning path and the measuring movement of the machine tool is an important guarantee for meeting the requirements of measuring precision and efficiency.
For the coordinate detection of such high-gradient complex curved surfaces and aspheric surfaces, cross-section contour lines with equal intervals are often adopted as scanning paths. However, the transverse equidistant cross-section profile method causes relatively sparse tracks near the poles, and the longitudinal equiangular cross-section profile method causes incomplete expression of a curved surface region far away from the center, and particularly for a high-gradient free-form surface with concave-convex fluctuation characteristics on the surface, the measuring points in the characteristic region are distributed sparsely, and the measuring accuracy is difficult to guarantee. On the other hand, the high gradient of the complex curved surface and the curvature change of the local concave-convex fluctuation characteristic require that the space attitude of the optical measuring head is changeable, and the surface shape is difficult to measure in situ, so that an in-situ measurement planning method suitable for the high gradient complex curved surface needs to be found.
In 2017, in patent CN105627923B of invention, by takawa et al, a scanning path planning method for blade dense point cloud acquisition based on laser ranging is invented, which divides and prolongs a profile curve of a section of a blade profile, generates a measurement path according to the divided curve, and uses a normal angle average value of a measurement area as a measurement angle. The method mainly aims at the off-line detection of the blade profile to carry out scanning path planning, and does not consider the influence of the motion of a measuring platform and the motion error on a measuring result. In 2019, wanglining et al invented a measurement point creation method based on an online measurement technology in patent CN106202843B, which includes obtaining information of points, lines or surfaces on a model to be processed, dividing a curved surface into a plurality of parts according to isoparametric lines, completing creation of measurement points on each curved surface piece in an equal distribution point manner, and generating a measurement path in an online measurement system. The method is difficult to ensure the measurement precision of the concave-convex fluctuation characteristics on the high-gradient free-form surface.
Disclosure of Invention
The invention mainly solves the technical problem of overcoming the defects of the method, and provides the high-gradient complex curved surface in-situ measurement planning method aiming at the requirements of high-precision and high-efficiency measurement of the complex curved surface in situ. According to the method, the non-equidistant transverse section contour line is generated by taking the equal illumination angle as a constraint condition, so that the problem of sparse measurement track near a pole caused by large change of the longitudinal height difference of the high-gradient curve is solved. And combining the generated non-equidistant transverse section lines with the longitudinal section lines to obtain a full-surface latticed scanning measurement path, so that the expression integrity of key regions, such as pole regions and equatorial regions, of the high-gradient complex curved surface and the aspheric part is improved. And the concave-convex characteristics of the surface are extracted according to the average curvature of the curved surface, and a local encrypted scanning contour line is generated, so that the measurement precision of the characteristic region is ensured. According to the equal illumination angle, a machine tool measuring motion track considering the sensor light beam incident angle is generated, frequent transposition of a measuring head is avoided, dynamic errors caused by multi-axis linkage of a machine tool are reduced, and precise and rapid on-site measurement of high-gradient complex curved surfaces can be realized.
The technical scheme adopted by the invention is an in-situ measurement planning method for a high-gradient complex curved surface, which is characterized in that in the measurement planning method, the central axis of the high-gradient complex curved surface is taken as a reference direction, an isolux line containing an aspheric surface in the reference direction is obtained by calculation according to the size of a given isolux angle, and a corresponding non-equidistant section contour line is taken as an initial scanning path of the high-gradient complex curved surface; secondly, generating equidistant section contour lines between two adjacent section contour lines to obtain a transverse scanning path; calculating a longitudinal section contour line according to a given angle division value to obtain a longitudinal scanning path; then, calculating the average curvature of the curved surface, extracting a concave-convex characteristic boundary line based on the change rate of the average curvature, and encrypting a scanning path in the characteristic region; and finally, performing multi-segment splicing measurement motion planning according to the generated scanning path, and performing measurement deflection angle inspection to complete the in-situ measurement planning of the complex curved surface. The method comprises the following specific steps:
step one, generating an initial scanning path
Firstly, the maximum gradient angle α of the inclusion aspheric surface A of the high-gradient complex curved surface S is calculated for guiding the selection of the equal illumination angle, and the maximum gradient angle α is the edge section circle l of the opening part of the inclusion aspheric surface AeqThe included angle between the normal direction of any upper point and the direction of the central axis. However, the device is not suitable for use in a kitchenAnd then, reasonably selecting an initial isolux angle and an angle increment according to the angle to calculate an isolux line containing the aspheric surface A.
Given an initial isoluminance angle β0At the same illumination angle, the points with the same illumination on the containing aspheric surface a are calculated as:
wherein, P (u, v) is any point on the containing aspheric surface A; u and v are curved line coordinate parameters;
calculating the points with the same illuminance as the unit reference vector to form an initial isolux line l0。
According to the measurement accuracy requirement and the incidence angle range allowed by the sensor light beam, setting the angle increment delta β to obtain the equal illumination angle set { βi|i＝0,1,2,...,n}，
βi＝β0+i×Δβ (2)
Wherein, Delta β is more than 0, βiNot more than α, and n is the number of equal illumination angles.
Finally, the isoluminance angle set { β is based on, in analogy to the initial isoluminance line calculationiI ═ 0,1, 2.., n } is calculated to obtain an isolux line set { liI ═ 0,1,2,. and n }. Extracting the height value of each isolux line, and collecting the height set { h) according to the obtained heightiAnd (i) 0,1,2, a.n., and further calculating to obtain a non-equidistant section contour line set { L ] on the high-gradient complex curved surface SiI ═ 0,1,2,. and n }, which is taken as the initial scan path.
Step two, generating a transverse scanning path
Generating equidistant section contour lines between two adjacent initial scanning paths, and setting the quantity of the transverse section contour lines increased between every two adjacent initial scanning paths as NaddDistance between equidistant sections { d }iI ═ 0,1,2,.., n-1} is:
increased height set of transverse cross-sectional contours hij|i＝0,1,2,...,n,j＝1,2,...,NaddIs calculated as:
hij＝hi+j·di(4)
according to the increased height set h of the profile line of the transverse cross sectionij|i＝0,1,2,...,n,j＝1,2,...,NaddCalculating to obtain an equidistant section contour line set (L) between the initial scanning pathsij|i＝0,1,2,...,n,j＝1,2,...,NaddTherein LijRepresenting the jth transverse cross-sectional profile line interposed between the ith and (i + 1) th initial scan paths, the initial set of scan paths { LiI 0,1,2, n and the set of equidistant cross-sectional contours { L |ij|i＝0,1,2,...,n,j＝1,2,...,NaddA set of transverse scan paths L that together form a complex surface S of high steepnessH。
Step three, generating a longitudinal scanning path
Generating a set of section planes HP of the central axis of the complex curved surface S with excessively high gradient according to the given angle division value theta, and cutting the complex curved surface S with high gradient by using the set of section planes HP to obtain a longitudinal scanning path LZGenerated transverse scan path LHAnd a longitudinal scan path LZGrid-shaped full-surface scanning measurement path L for forming high-gradient complex curved surface SGlobal。
Fourthly, generating a scanning path of the concave-convex local area of the surface
Constructing a discrete parameter grid matrix P according to the parameter expression of the high-gradient complex curved surface S, wherein parameter grid nodes P in the discrete parameter grid matrix PijThe corresponding curved line coordinate is (u)i,vj) I 1,2, 3., n, j 1,2, 3., m. Calculating the node P of each parameter mesh of the high-gradient complex curved surface Sij(ui,vj) The average curvature H is determined as an average curvature change threshold Th, and the concave-convex characteristic region is determined based on the average curvature change threshold Th.
The average curvature H is calculated according to the first basic quantity and the second basic quantity of the high-gradient complex curved surface S, and the calculation formula is as follows:
wherein E, F, G is the first basic quantity of the complex surface S with high gradient, and L, M, N is the second basic quantity of the complex surface S with high gradient.
Then, determining an average curvature change threshold Th, and determining a concave-convex fluctuation characteristic region according to the average curvature change threshold Th; firstly, calculating average curvature change ratio components in two parameter directions according to average curvature change values in the two parameter directions, wherein the average curvature change ratio components are respectively upsilon Hu(ui,vj) And upsilon Hv(ui,vj) Specifically, it is calculated according to the following formula:
then, the average curvature change ratios in the two directions are synthesized to obtain an average curvature change ratio upsilonh (u) of the complex curved surface S with high gradienti,vj) The calculation formula is as follows:
then, the average curvature change ratio upsilonH (u) of each discrete parameter grid line along two parameter directions is obtainedi,vj) Is set to the minimum value among the respective maximum values as the average curvature change threshold value Th, i.e.
Determining parameter grid nodes belonging to the characteristic region according to the set average curvature change threshold ThThe mean curvature is changed by a ratio v H (u)i,vj) Nodes larger than the average curvature change threshold Th are regarded as points in the concave-convex feature region and are marked as "1", and other nodes are marked as "0", thereby generating a concave-convex feature matrix BijThe method specifically comprises the following steps:
finally, according to the obtained concave-convex characteristic matrix BijAnd determining a characteristic separation curve, and extracting a boundary curve of the concave-convex characteristic by adopting a boundary tracking algorithm of eight-direction chain codes, namely using the initial point coordinate and the boundary point direction of the characteristic separation curve. Thereby forming a sequence SC representing the characteristic separation curve.
In the concave-convex characteristic region, a group of local longitudinal equiangular section planes of the S central axis of the complex curved surface with overhigh gradient are generated
Using the set of local longitudinal equiangular cross-sectional planes
Intercepting a high-gradient complex curved surface S, and taking a sequence SC of characteristic separation curves as a boundary to obtain a local longitudinal scanning path
Step five in-place measurement movement planning
According to the obtained isoluminance angle set { βiI ═ 0,1,2,.., n }, full-surface scan measurement path LGlobalAnd a local scan measurement path LLocalAnd performing in-situ measurement motion planning to obtain a motion track of the rotation center point of the sensor.
Along transverse scan path LHWhen the measurement is carried out, the optical axis of the optical measuring head is ensured to be along the normal direction of the inclusion aspheric surface A of the complex curved surface S with high gradient, and the longitudinal scanning path L is followedZAnd a partial longitudinal scan path
When the optical measuring head is used for measurement, the included angle between the optical axis of the optical measuring head and the central axis of the high-gradient complex curved surface S is βiFor the equal illumination angle βiAnd βi+1The longitudinal section contour line between the two parts is continuously scanned and measured, when the optical measuring head moves to the equal illumination angle of βi+1When the position of the optical probe is determined, the included angle between the optical axis of the optical probe and the central axis of the high-gradient complex curved surface S is βi+1For the equal illumination angle βi+1And βi+2And continuously scanning and measuring the longitudinal section contour line between the two curved surfaces, thereby realizing the sectional scanning and measuring of the longitudinal section contour line of the high-gradient complex curved surface S.
Step six measurement deflection angle inspection
Checking whether the normal included angle gamma between the optical axis of the optical probe and the complex curved surface S with high gradient at each scanning sampling point exceeds the allowable deflection angle of the optical probe, LHWhen measuring, the included angle gammahCalculated according to the following formula:
wherein the content of the first and second substances,
to contain the unit normal vector of any point on the aspheric surface a,
is a unit normal vector of any point on the complex curved surface S with high gradient in the longitudinal scanning path LZAnd a partial longitudinal scan path
When the sectional scanning measurement is carried out, the included angle gamma is formed on each section of longitudinal section contour linezCalculated according to the following formula:
wherein the content of the first and second substances,
is a unit reference vector.
If the angle gamma at each scanning sampling point is includedhAnd gammazAll within the allowable deflection angle range of the optical measuring head, the planned scanning path and the measuring motion are effective, otherwise, the angle increment delta β set in the step one needs to be reduced.
Step seven generating in-situ measuring program
According to the obtained grid-shaped full-surface scanning measuring path LGlobalAnd a partial longitudinal scan path
Generating the rotation center coordinates of the sensor under the coordinate system of the machine tool, creating a G instruction file, giving the motion parameters of the machine tool and the motion instructions of all axes, and storing the G instruction file as a txt file.
The method has the advantages that the non-equidistant transverse section contour lines are generated by taking the equal illumination angle as the constraint condition, and the generated non-equidistant transverse section lines are combined with the longitudinal section lines to obtain the full-surface latticed scanning measurement path. The problem of measurement track sparseness near the pole caused by large vertical height difference change of the high-gradient curved surface and the problem that a curved surface high-gradient area and a concave-convex characteristic area cannot be completely expressed due to the fact that equidistant section contour lines are adopted as scanning paths are solved. According to the isolux angle, a machine tool measuring motion track considering the sensor light beam incident angle is generated, frequent transposition of a measuring head is avoided, meanwhile, the extraction of the rotary worktable reference coordinate is effectively avoided, the nonlinear error caused by interpolation motion of the rotary worktable is reduced, and the characteristic region measuring precision is ensured. The scanning measurement movement direction is specified, and the measurement error caused by the reverse clearance of the linear shaft is avoided; meanwhile, dynamic errors caused by multi-axis linkage of the machine tool are reduced, and the expression integrity of key areas, such as pole and equator areas, of high-gradient complex curved surfaces and aspheric parts is improved. The method has strong universality, and can realize precise and rapid in-situ measurement of the high-gradient curved surface part on a multi-axis numerical control machine tool or a coordinate measuring machine.
Drawings
FIG. 1 is a flow chart of the planning method of the present invention;
FIG. 2 is a schematic view of scan path planning, wherein LHTransverse scan path, LZ-a longitudinal scanning path,
a local longitudinal scan path; leq-containing the aspherical a mouth edge cross-section circle;
edge section circle l of mouth part of containing aspheric surface AeqA unit normal vector of an upper arbitrary point;
α -maximum steepness angle α of the inclusion aspheric surface A of the complex curved surface S with high steepness;
fig. 3-schematic diagram of transverse measurement motion planning, wherein: 1-optical probe, a-center line of optical probe 1,
ith transverse scanning path, Bi-the minimum containing circle of the ith transverse scanning path, the center of the O-minimum containing circle, the P-measuring point on the ith transverse scanning path, and the normal direction of the corresponding minimum containing circle at the T-measuring point P;
FIG. 4 is a schematic diagram of a lateral measurement movement plan, wherein LZ1A first longitudinal scan path, τi-1First longitudinal scan path LZ1Inner i-1 th scan line, τiFirst longitudinal scan path LZ1The inner i-th segment of the scanning line,
first longitudinal scan path LZ1The starting control point of the i-1 th scanning line,
first longitudinal scan path LZ1Starting control point, T, of the i-th scanning linei-1First longitudinal scan path LZ1Measuring direction vector, T, of the i-1 th scan lineiFirst longitudinal scan path LZ1Measuring a direction vector of an ith scanning line;
FIG. 5-measurement of deflection angle γhInspection schematic, wherein: gamma raymax-maximum deflection angle allowed for the optical probe.
Detailed Description
The detailed description of the embodiments of the invention is provided in conjunction with the technical solutions and the accompanying drawings.
In this embodiment, the high-gradient complex curved surface S is a free-form surface having concave-convex undulation characteristics on the surface, the height is 52.5mm, the caliber is 100mm, and there are 4 non-rotationally symmetric pit characteristics in the circumferential direction. FIG. 1 is a flow chart of the planning method of the present invention, and the in-situ measurement planning of the curved surface comprises the following specific steps:
step one, generating an initial scanning path
Firstly, the maximum steepness angle α of the inclusion aspheric surface A of the complex curved surface S with high steepness is calculated, the maximum steepness angle α is the section circle l of the edge of the mouth part of the inclusion aspheric surface AeqUnit normal vector of upper arbitrary point
And unit reference vector
The angle therebetween, the maximum steepness angle α in this embodiment is 61.5367 deg., as shown in FIG. 2. then the unit normal vector containing any point P (u, v) on aspheric surface A is calculated as
The central axis of the complex curved surface S with high gradient or the containing aspheric surface A thereof is selected as a reference direction, and the reference direction in the embodiment is [0,0,1 ] in the workpiece coordinate system]Given an initial isolux angle β1＝0.6046°，Calculating the points with the same illuminance according to the formula (1) to form an initial isolux line l0According to the measurement accuracy requirement and the incidence angle range allowed by the sensor beam, the given angle increment delta β is 4 degrees, and the equal illumination angle set { β ] is obtained by using the formula (2)iI 0,1,2,.., 14, finally, the same principle as for calculating the initial isoluminance line is followed from the set of isoluminance angles { βiCalculating | i ═ 0,1, 2.., 14} to obtain an isolux line set { liI ═ 0,1,2,. ·,14 }. Extracting the height value of each isophote line to obtain a height set { h }iI ═ 0,1,2,.., 14}, and table 1 lists the calculated height values of the 15 equal luminance lines.
TABLE 1 Isoluminance line height value h containing aspheric surface Ai(mm)
According to the height set hiCalculating to obtain a non-equidistant section contour line on the high-gradient complex curved surface S, and taking the non-equidistant section contour line as an initial scanning path { L | (I ═ 0,1, 2.. times.14) }i|i＝0,1,2,...,14}。
Step two, generating a transverse scanning path
Equidistant cross-sectional profile lines are generated between two adjacent initial scanning paths, and the quantity N of the transverse cross-sectional profile lines increased between the two adjacent initial scanning paths in the embodimentaddTo 2, according to the increased set of heights of the transverse section contour lines hijI 0,1,2, 14, j 1,2, the equidistant cross-sectional profile line set { L } between the initial scan paths is calculatedij0,1,2, 14, j 1,2, L being part of the total number of wordsijRepresenting the jth transverse cross-sectional profile line interposed between the ith and the (i + 1) th isophote corresponding initial scan paths, the initial set of scan paths { LiI-0, 1,2, 14 and equidistant cross-sectional profile set { L }ijI 0,1,2, 14, j 1,2, collectively form a transverse scan path L of a complex curved surface S of high steepnessHAnd 43 pieces in total. Table 2 lists the calculated height values for the transverse scan path.
TABLE 2 transverse scan path height value (mm) of high-steepness Complex surface S
Step three, generating a longitudinal scanning path
Given an angle division value theta of 20 degrees, a set of section planes HP of the central axis of the complex curved surface S with excessively high gradient is generated, the complex curved surface S with high gradient is obtained by using the set of section planes HP, and a longitudinal scanning path L is obtainedZ18 total transverse scan paths LHAnd a longitudinal scan path LZGrid-shaped full-surface scanning measurement path L for forming high-gradient complex curved surface SGlobal。
Step four, extracting the surface concave-convex fluctuation characteristics and generating a local scanning path
Constructing a discrete parameter grid matrix P according to the parameter expression of the high-gradient complex curved surface S, wherein parameter grid nodes P in the discrete parameter grid matrix PijThe corresponding curved line coordinate is (u)i,vj) I 1,2, 3., n, j 1,2, 3., m. Calculating the node P of each parameter mesh of the high-gradient complex curved surface S according to the formula (5)ij(ui,vj) The average curvature H is determined as an average curvature change threshold Th, and the concave-convex characteristic region is determined based on the average curvature change threshold Th.
The average curvature change threshold Th is determined by first calculating average curvature change ratio components in two parameter directions, each expressed as ν H, from average curvature change values in the two parameter directions by using equations (6) and (7)u(ui,vj) And upsilon Hv(ui,vj) Then, the average curvature change ratios in the two directions are synthesized according to the formula (8) to obtain an average curvature change ratio υ H (u) of the complex curved surface S with high gradienti,vj). Then, the average curvature change ratio v H (u) of each discrete parameter grid line in two parameter directions is obtained by equation (9)i,vj) The minimum value among the maximum values is set as the average curvature change threshold Th.
Determining according to the set average curvature variation threshold ThA parameter grid node belonging to the characteristic region and the average curvature change ratio upsilon H (u)i,vj) The nodes larger than the average curvature change threshold Th are regarded as points in the concave-convex characteristic region and marked as '1', and the other nodes are marked as '0', so that a concave-convex characteristic matrix B is generatedij. Finally, according to the obtained concave-convex characteristic matrix BijAnd determining a characteristic separation curve, and extracting a boundary curve of the concave-convex characteristic by adopting a boundary tracking algorithm of eight-direction chain codes. Thereby forming a sequence SC representing the characteristic separation curve.
In the concave-convex characteristic region, a group of complex curved surfaces S with overhigh gradient or local longitudinal equiangular sectional planes containing the central axis of the aspheric surface A are generated
Using the set of local longitudinal equiangular cross-sectional planes
Intercepting a high-gradient complex curved surface S, and taking a sequence SC of characteristic separation curves as a boundary to obtain a local longitudinal scanning path
The resulting scan measurement path is shown in fig. 2.
Step five in-place measurement movement planning
According to the obtained isoluminance angle set { βiI ═ 0,1,2,.., n }, full-surface scan measurement path LGlobalAnd a local scan measurement path LLocalAnd performing in-situ measurement motion planning to obtain a motion track of the rotation center point of the sensor.
Along the ith transverse scanning path
When the measurement is carried out, the corresponding minimum containing circle B at each measuring point P is calculatediAnd the centre line a of the optical probe 1 is adjusted to measure along this direction, as shown in fig. 3.
Scanning in longitudinal directionPath LZAnd a partial longitudinal scan path
While taking the measurement, the first longitudinal scan path L is usedZ1For example, as shown in FIG. 4, the optical probe 1 moves to a first longitudinal scan path LZ1Initial control point of i-1 th scanning line
And automatically adjusts the center line a of the optical probe 1 and the first longitudinal scanning path LZ1Measuring direction vector T of i-1 th scanning line in internali-1Overlapping to ensure that the included angle between the optical axis of the optical probe 1 and the central axis of the high-gradient complex curved surface S is βi-1The optical probe 1 is continuously moved to the first longitudinal scan path LZ1Initial control point of i-th scanning line
The center line a of the optical probe 1 is aligned with the first longitudinal scanning path LZ1Measuring direction vector T of inner ith scanning lineiOverlapping to ensure that the included angle between the optical axis of the optical probe and the central axis of the high-gradient complex curved surface S is βiThe optical probe 1 is scanned along a first longitudinal scan path LZ1The scan lines in each segment are measured sequentially.
Step six measurement deflection angle inspection
Checking whether the normal included angle gamma between the optical axis of the optical measuring head and the high-gradient complex curved surface S at each scanning sampling point exceeds the allowable deflection angle of the optical measuring head, wherein the allowable deflection angle of the optical measuring head is +/-30 degrees in the embodiment, L is carried out along the transverse scanning pathHWhen the measurement is performed, γ is calculated according to the formula (11)h20.0427 deg., as shown in fig. 5, along the longitudinal scan path LZAnd a partial longitudinal scan path
When the segmented scanning measurement is carried out, the included angle gamma is calculated according to the formula (12)zIs 14.8478 deg.. ClipAngle gammahAnd gammazAre all smaller than the allowable deflection angle of the optical measuring head, and the generated measuring path and the planned measuring movement are effective.
Step seven generating in-situ measuring program
According to the obtained grid-shaped full-surface scanning measuring path LGlobalAnd a partial longitudinal scan path
Generating the rotation center coordinates of the sensor under the coordinate system of the machine tool, creating a G instruction file, giving the motion parameters of the machine tool and the motion instructions of all axes, and storing the G instruction file as a txt file.
The invention realizes the generation of the in-situ scanning path of the high-gradient complex curved surface and the planning of the measurement motion, effectively avoids the reference coordinate extraction of the rotary worktable, reduces the dynamic error caused by the multi-axis linkage of the machine tool, ensures the measurement precision of the characteristic region, improves the expression integrity of the high-gradient complex curved surface and the key region (such as the pole and the equatorial region) of the aspheric part, completes the automatic generation of the in-situ measurement program, and realizes the precise and rapid in-situ measurement of the high-gradient complex curved surface.
Claims (1)
1. An in-situ measurement planning method for a high-gradient complex curved surface is characterized in that in the measurement planning method, firstly, the central axis of the high-gradient complex curved surface is used as a reference direction, an isolux line containing an aspheric surface in the reference direction is obtained through calculation according to the size of a given isolux angle, and a corresponding non-equidistant section contour line is used as an initial scanning path of the high-gradient complex curved surface; secondly, generating equidistant section contour lines between two adjacent section contour lines to obtain a transverse scanning path; calculating a longitudinal section contour line according to a given angle division value to obtain a longitudinal scanning path; then, calculating the average curvature of the curved surface, extracting a concave-convex characteristic boundary line based on the change rate of the average curvature, and encrypting a scanning path in the characteristic region; finally, performing multi-segment splicing measurement motion planning according to the generated scanning path, and performing measurement deflection angle inspection to complete the in-situ measurement planning of the complex curved surface; the planning method comprises the following specific steps:
first step generating an initial scan path
Firstly, calculating the maximum gradient angle α of the inclusion aspheric surface A of the high-gradient complex curved surface S, then reasonably selecting an initial isolux angle and an angle increment according to the angle for calculating an isolux line of the inclusion aspheric surface A, and giving an initial isolux angle β0At the same illumination angle, the points with the same illumination on the containing aspheric surface a are calculated as:
wherein, P (u, v) is any point on the containing aspheric surface A; u and v are curved line coordinate parameters;
calculating the points with the same illuminance as the unit reference vector to form an initial isolux line l0；
Setting the angle increment delta β to obtain the equal illumination angle set { βi|i＝0,1,2,...,n}，
βi＝β0+i×Δβ (2)
Wherein, Delta β is more than 0, βiNot more than α, n is the number of equal illumination angles, the same as the calculation of the initial equal illumination line, according to the equal illumination angle set { β%iI ═ 0,1, 2.., n } is calculated to obtain an isolux line set { liI ═ 0,1,2,. n }; extracting the height value of each isolux line, and collecting the height set { h) according to the obtained heightiAnd (i) 0,1,2, a.n., and further calculating to obtain a non-equidistant section contour line set { L ] on the high-gradient complex curved surface SiI ═ 0,1,2, ·, n }, which is taken as the initial scan path;
second step of generating transverse scan path
Generating equidistant section contour lines between two adjacent initial scanning paths, and setting the quantity of the transverse section contour lines increased between every two adjacent initial scanning paths as NaddDistance between equidistant sections { d }iI ═ 0,1,2,.., n-1} is:
increased height set of transverse cross-sectional contours hij|i＝0,1,2,...,n,j＝1,2,...,NaddIs calculated as:
hij＝hi+j·di(4)
according to the increased height set h of the profile line of the transverse cross sectionij|i＝0,1,2,...,n,j＝1,2,...,NaddCalculating to obtain an equidistant section contour line set (L) between the initial scanning pathsij|i＝0,1,2,...,n,j＝1,2,...,NaddTherein LijRepresenting the jth transverse cross-sectional profile line interposed between the ith and (i + 1) th initial scan paths, from which the initial set of scan paths { LiI 0,1,2, n and the set of equidistant cross-sectional contours { L |ij|i＝0,1,2,...,n,j＝1,2,...,NaddA set of transverse scan paths L that together form a complex surface S of high steepnessH；
Third step of generating longitudinal scan path
Generating a set of section planes HP of the central axis of the complex curved surface S with excessively high gradient according to the given angle division value theta, and cutting the complex curved surface S with high gradient by using the set of section planes HP to obtain a longitudinal scanning path LZTransverse scan path LHAnd a longitudinal scan path LZGrid-shaped full-surface scanning measurement path L for forming high-gradient complex curved surface SGlobal；
Fourthly, generating a scanning path of the concave-convex local area of the surface
Constructing a discrete parameter grid matrix P according to the parameter expression of the high-gradient complex curved surface S, wherein parameter grid nodes P in the discrete parameter grid matrix PijThe corresponding curved line coordinate is (u)i,vj) 1,2,3,., n, j 1,2,3,. and m; calculating the node P of each parameter mesh of the high-gradient complex curved surface Sij(ui,vj) Determining an average curvature change threshold Th according to the average curvature change threshold Th;
the average curvature H is calculated according to the first basic quantity and the second basic quantity of the high-gradient complex curved surface S, and the calculation formula is as follows:
wherein E, F, G is a first basic quantity of the high-gradient complex curved surface S, and L, M, N are second basic quantities of the high-gradient complex curved surface S;
determining an average curvature change threshold Th, and determining a concave-convex fluctuation characteristic region according to the average curvature change threshold Th; firstly, calculating average curvature change ratio components in two parameter directions according to average curvature change values in the two parameter directions, wherein the average curvature change ratio components are respectively upsilon Hu(ui,vj) And upsilon Hv(ui,vj) Specifically, it is calculated according to the following formula:
synthesizing the average curvature change ratios of the two directions to obtain the average curvature change ratio upsilonH (u) of the high-gradient complex curved surface Si,vj) The calculation formula is as follows:
acquiring the average curvature change ratio upsilonH (u) of each discrete parameter grid line along two parameter directionsi,vj) Is set to the minimum value among the respective maximum values as the average curvature change threshold value Th, i.e.
According to a set mean curvature variation thresholdDetermining parameter grid nodes belonging to the characteristic region, and determining average curvature change ratio upsilon H (u) by using the value Thi,vj) Nodes larger than the average curvature change threshold Th are regarded as points in the concave-convex feature region and are marked as "1", and other nodes are marked as "0", thereby generating a concave-convex feature matrix BijThe method specifically comprises the following steps:
finally, according to the obtained concave-convex characteristic matrix BijDetermining a characteristic separation curve, and extracting a boundary curve of concave-convex characteristics by adopting a boundary tracking algorithm of eight-direction chain codes, namely using the initial point coordinates and the boundary point directions of the characteristic separation curve; thereby forming a sequence SC representing the characteristic separation curve;
in the concave-convex characteristic region, a group of local longitudinal equiangular section planes of the S central axis of the complex curved surface with overhigh gradient are generated
Using the set of local longitudinal equiangular cross-sectional planes
Intercepting a high-gradient complex curved surface S, and taking a sequence SC of characteristic separation curves as a boundary to obtain a local longitudinal scanning path
Fifth step in-situ measurement exercise planning
According to the obtained isoluminance angle set { βiI ═ 0,1,2,.., n }, full-surface scan measurement path LGlobalAnd a local scan measurement path LLocalPerforming in-situ measurement motion planning to obtain a motion track of a rotation central point of the sensor;
along transverse scan path LHWhen measurement is carried out, the optical axis of the optical measuring head is ensured to be along the normal direction of the high-gradient complex curved surface S containing the aspheric surface A; sweeping along the longitudinal directionTracing LZAnd a partial longitudinal scan path
When the optical measuring head is used for measurement, the included angle between the optical axis of the optical measuring head and the central axis of the high-gradient complex curved surface S is βiFor the equal illumination angle βiAnd βi+1The longitudinal section contour line between the two parts is continuously scanned and measured, when the optical measuring head moves to the equal illumination angle of βi+1When the position of the optical probe is determined, the included angle between the optical axis of the optical probe and the central axis of the high-gradient complex curved surface S is βi+1For the equal illumination angle βi+1And βi+2Continuous scanning measurement is carried out on the longitudinal section contour line between the two curved surfaces, so that sectional scanning measurement of the longitudinal section contour line of the high-gradient complex curved surface S is realized;
sixthly, measuring deflection angle inspection
Checking whether the normal included angle gamma between the optical axis of the optical probe and the complex curved surface S with high gradient at each scanning sampling point exceeds the allowable deflection angle of the optical probe, and scanning along the transverse scanning path LHWhen measuring, the included angle gammahCalculated according to the following formula,
wherein the content of the first and second substances,
to contain the unit normal vector of any point on the aspheric surface a,
is a unit normal vector of any point on the complex curved surface S with high gradient, and is arranged along the longitudinal scanning path LZAnd a partial longitudinal scan path
When the sectional scanning measurement is carried out, the included angle gamma is formed on each section of longitudinal section contour linezAccording to the following formulaIn the calculation, the calculation is carried out,
wherein the content of the first and second substances,
is a unit reference vector; if the angle gamma at each scanning sampling point is includedhAnd gammazAll in the allowable deflection angle range of the optical measuring head, the planned scanning path and the planned measuring motion are effective, otherwise, the angle increment delta β set in the step one needs to be reduced;
step seven generating in-situ measuring program
According to the obtained grid-shaped full-surface scanning measuring path LGlobalAnd a partial longitudinal scan path
Generating the rotation center coordinates of the sensor under the coordinate system of the machine tool, creating a G instruction file, giving the motion parameters of the machine tool and the motion instructions of all axes, and storing the G instruction file as a txt file.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910947275.9A CN110500969B (en) | 2019-10-08 | 2019-10-08 | High-gradient complex curved surface in-situ measurement planning method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910947275.9A CN110500969B (en) | 2019-10-08 | 2019-10-08 | High-gradient complex curved surface in-situ measurement planning method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110500969A CN110500969A (en) | 2019-11-26 |
| CN110500969B true CN110500969B (en) | 2020-07-14 |
Family
ID=68593171
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910947275.9A Active CN110500969B (en) | 2019-10-08 | 2019-10-08 | High-gradient complex curved surface in-situ measurement planning method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110500969B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111060057B (en) * | 2019-12-25 | 2022-01-28 | 贵阳航发精密铸造有限公司 | Turbine blade profile measuring method based on three-coordinate measuring machine |
| CN111238366B (en) * | 2020-01-09 | 2021-10-22 | 天远三维（天津）科技有限公司 | Three-dimensional scanning path planning method and device |
| CN112595260B (en) * | 2020-12-29 | 2022-05-31 | 广东三姆森科技股份有限公司 | Method, system, storage medium and equipment for extracting irregular cambered surface contour |
| CN113251949B (en) * | 2021-06-18 | 2021-11-30 | 三代光学科技（天津）有限公司 | Method for generating single-point optical measurement path of micro-lens array surface shape |
| CN113465506A (en) * | 2021-06-28 | 2021-10-01 | 西安交通大学 | Method for planning full-data measurement path of blade of aircraft engine |
| CN117349764B (en) * | 2023-12-05 | 2024-02-27 | 河北三臧生物科技有限公司 | Intelligent analysis method for stem cell induction data |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4209252A (en) * | 1978-07-03 | 1980-06-24 | Arditty Herve J | Optical probe assembly for detecting the position of an object surface and method |
| US5784168A (en) * | 1995-07-03 | 1998-07-21 | U.S. Philips Corporation | Position detection system for an object with at least five degrees of freedom |
| CN102501172B (en) * | 2011-11-22 | 2013-10-23 | 清华大学 | On-site measurement method applied to space curved surface machining for robot grinding system |
| CN105627923B (en) * | 2016-01-08 | 2017-10-20 | 黑龙江科技大学 | A kind of planning parameters of scanning paths method that blade dense point cloud based on laser ranging is obtained |
| JP6875804B2 (en) * | 2016-08-24 | 2021-05-26 | ケイミュー株式会社 | Building board precut system, building board precut method, and program |
| JP6937482B2 (en) * | 2017-03-27 | 2021-09-22 | 株式会社東京精密 | Surface shape measuring device and its stitching measuring method |
| CN108682043A (en) * | 2018-02-08 | 2018-10-19 | 大连理工大学 | A kind of complex-curved measure planning method based on parameter mapping |
| CN108734766B (en) * | 2018-05-17 | 2022-04-08 | 业成科技（成都）有限公司 | Method for evaluating curvature radius of curved surface device |
| CN110017790B (en) * | 2019-03-15 | 2021-02-09 | 南京航空航天大学 | Curved surface scanning track generation and optimization method based on measurement precision |
-
2019
- 2019-10-08 CN CN201910947275.9A patent/CN110500969B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN110500969A (en) | 2019-11-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110500969B (en) | High-gradient complex curved surface in-situ measurement planning method | |
| CN106643551B (en) | A kind of quick scanning means of blade shape and method | |
| CN100435055C (en) | Method for planning smooth and non-interference tool route of 5-axis numerical control machining | |
| CN103453849B (en) | The complex curved surface parts method for three-dimensional measurement that many optical sensors are collaborative and system | |
| CN102494657B (en) | Measuring head radius compensation method for curve surface profile measuring and detecting | |
| CN110095060A (en) | Steel construction rapid quality detection method based on 3-D scanning technology | |
| ElKott et al. | Isoparametric line sampling for the inspection planning of sculptured surfaces | |
| CN101986350A (en) | Monocular structured light-based three-dimensional modeling method | |
| CN101634544A (en) | Water turbine blade blank profile measuring and machining allowance analyzing method | |
| CN102209941A (en) | Systems and methods for machining materials | |
| Li et al. | Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface | |
| CN101539397A (en) | Method for measuring three-dimensional attitude of object on precision-optical basis | |
| Lai et al. | Machining error inspection of T-spline surface by on-machine measurement | |
| Dong et al. | An improved signal processing method for the laser displacement sensor in mechanical systems | |
| Zhang et al. | Optimisation of camera positions for optical coordinate measurement based on visible point analysis | |
| CN102661742B (en) | Self-adaptive mark point layout method based on curvature characteristic weighting centroid point constraint | |
| CN112033385A (en) | Pier pose measuring method based on mass point cloud data | |
| Sang et al. | A new scanning lines distribution strategy for the form error evaluation of freeform surface on CMM | |
| CN108614519A (en) | One kind being based on the online error measuring system of laser dot-matrix numerically-controlled machine tool and method | |
| CN109202539B (en) | Online detection method for composite material weak-rigidity special-shaped structure | |
| Pechenin et al. | Optimization of measurements of the geometry of parts with complex surfaces | |
| CN108646669B (en) | Approximate evaluation method for surface contour error of curved surface machining part | |
| Pham et al. | Reverse engineering–hardware and software | |
| CN106931950B (en) | LNG pipeline attitude detecting method based on three-dimensional laser detection | |
| Pathak et al. | Investigating alignment effect on inspection accuracy of AM part using 3D scanner |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |