CN102430779B - Device for measuring normal vector at arbitrary point on free-form surface and measuring method thereof - Google Patents

Abstract

The invention provides a device for measuring a normal vector at an arbitrary point on a free-form surface and a measuring method thereof. The device comprises a body fixing assembly and four deflected angle measuring mechanisms. The four deflected angle measuring mechanisms form a cross-shaped structure which is installed on the body fixing assembly. Each deflected angle measuring mechanism comprises angle sensors, contact rods and spherical contacts. The measuring shafts of opposite angle sensors are parallel and the measuring shafts of adjacent angle sensors are vertical. The central line of two opposite spherical contacts is vertical to that of another two opposite spherical contacts. The two central lines are intersected with the central axis of external machining arms. The measuring method comprises the steps of: during measurement, marking curves on the free-form surface twice respectively through four spherical contacts to form an orthogonal plane; correcting the angle of the central axis of external machining arms; and further obtaining the normal vector of the point to measure. With adoption of the method provided by the invention, less measuring data points are employed without the complex process of surface fitting and the precision of the device meets the actual requirements when curved surface with greater curvature is measured so that the invention is convenient to use.

Description

A kind of device and measuring method thereof of measuring normal vector of arbitrary point of free-form surface

Technical field

The present invention relates to measure the detection technique field, be specially a kind of device and measuring method thereof of measuring normal vector of arbitrary point of free-form surface.

Background technology

In field of machining, flexible drilling is the important step to the riveting of thin-wall construction flexible drilling, the perpendicularity of position, hole, riveting point directly has influence on the wallboard riveting quality, in the application of the coverings such as aircraft, bullet train, wallboard curvature high complexity, very high requirement has been proposed for the normal direction centering of flexible drilling.Because covering adopts riveted structure more, boring method will directly affect the aerodynamic configuration of covering and even the security performance of modular construction to the overproof hole mass defect that causes of precision.Aircraft skin is generally very thin, and has complicated curvature, and the normal direction in hole changes with curved profile, and during boring, Normal Error has obvious impact to the quality in hole.If rivet hole and Skinning Surfaces direction of normal angle are excessive, will cause rivet can not vertically squeeze into covering, destroy the skin-surface smoothness, and cause the part riveted joint for connecting by force, make connected piece in the junction discontinuity, greatly affect quality of connection and aerodynamic configuration.In addition, the covering parts drilling hole amounts such as aircraft, bullet train are huge, and hand drill exists the outstanding problems such as quality conformance is poor, efficient is low, raising drilling efficient and quality that the drilling of employing robot flexibility can be larger.Along with the raising of Production requirement, adopting automation boring is inexorable trend.Therefore, boring method more and more shows huge application demand to on-line measurement and the adjustment of precision.

At present, both at home and abroad on definite free form surface commonly used the method for any point place normal vector as follows:

1, manual leveling method: when namely adopting hand drill, if error or local deformation appear in the installation of covering parts, operating personnel can rule of thumb suitably adjust angle of drill bit and guarantee the normal direction precision of holing, and perhaps adopt a kind of specific device (as boring cup, drill bushing) to proofread and correct.During boring, 3 legs withstand on surface of the work, make cup-shaped device perpendicular to surface of the work.Cup-shaped device is enclosed within on drill bit, makes cup-shaped device be close to surface of the work by spring preload power, and drill bit can stretch out and retract along gathering sill, thereby when guaranteeing boring, drilling tool is basically perpendicular to the surface of workpiece.The deficiency of the method is self experience that long and vertical precision of leveling time mainly relies on operating personnel, and efficient is low and versatility is poor, is difficult to guarantee precision, can not satisfy the measurement requirement of digital control system automatic flexible drilling.

2, tri patch method: namely adopt small planar delta approximate simulation deformation surface, normal is determined by 3 plane triangles that form.Version according to right angled triangle is installed 3 displacement transducers around the presser feet of bore hole axis, when presser feet is pressed theoretical normal direction compacting part, if cutter is perpendicular to parts surface, the measured value of 3 displacement transducers equates, if out of plumb, the measured value of 3 displacement transducers is unequal, according to the difference of displacement sensor value, can calculate the normal error of cutter and skin-surface, namely the actual normal direction of covering and theory method to deviation.The deficiency of the method is owing to adopting small planar delta approximate simulation deformation surface, having enlarged the perpendicular positioning error, can produce certain influence to certainty of measurement, and when the curvature of curved surface to be measured was larger, certainty of measurement was difficult to guarantee.

3, Surface Fitting: namely carry out surface fitting by the data point that gathers on curved surface to be measured, obtain a patch approximate with curved surface to be measured, then obtained the normal vector of tested point according to this patch.The method calculation of complex, workload is larger, often needs to obtain the coordinate of tens data points on curved surface, just can obtain higher computational accuracy.Restriction due to measuring technique, operating efficiency and automatic Drilling/Riveting plant machinery structure, in actual automatic Drilling/Riveting process, can't realize the measurement of the surperficial mass data point coordinates of skinpiston, make the method lose the prerequisite of using, can not effectively solve Real-time solution brill riveting point normal vector problem in the automatic Drilling/Riveting process.

Summary of the invention

The technical problem that solves

Have problems for solving in prior art, the present invention proposes a kind of device and measuring method thereof of measuring normal vector of arbitrary point of free-form surface.

Technical scheme

Technical scheme of the present invention is:

described a kind of device of measuring normal vector of arbitrary point of free-form surface is characterized in that: comprise a main body fixation kit and four measurement of angle mechanisms, each measurement of angle mechanism comprises angular transducer, feeler lever and spherical contact, and the feeler lever outer end is connected with spherical contact, and the feeler lever other end is measured axle with angular transducer and is fixedly connected with, and angular transducer is measured feeler lever and is driven angular transducer and measure the angle that axle rotates, the main body fixation kit comprises connection base and box body, connecting base and box body is fixedly linked, connecting base and exterior mechanical process arm is fixedly linked, the box body side is evenly equipped with four radial grooves, four radial grooves are crossing distribution, four measurement of angle mechanisms are placed on respectively in four radial grooves, and the angular transducer by separately is fixedly connected with box body respectively, it is parallel that the angular transducer of two measurement of angle mechanisms that the position is relative is measured axle, it is vertical that the angular transducer of two measurement of angle mechanisms that the position is adjacent is measured axle, the centre of sphere line of the spherical contact of the measurement of angle mechanism that the centre of sphere line of the spherical contact of two measurement of angle mechanisms that the position is relative is relative with two other position is vertical, and two centre of sphere line and exterior mechanical process arm central axis all intersect, the feeler lever of each measurement of angle mechanism also is connected with box body by reset tension spring in the end end that it is connected with angular transducer.

Described a kind of device of measuring normal vector of arbitrary point of free-form surface, it is characterized in that: also include the feeler lever limiting plate, the platy structure of symmetry centered by described feeler lever limiting plate, be fixed on box body back to a side that connects base, and feeler lever limiting plate central axis and external process arm central axis conllinear, the feeler lever limiting plate is used for determining the initial outer drift angle of feeler lever.

Described a kind of device of measuring normal vector of arbitrary point of free-form surface, it is characterized in that: also include low coverage touching alarm, low coverage touching alarm is fixed on the feeler lever limiting plate, the distance that is used for measurement mechanism and free form surface, and give the alarm during less than setting value in the distance of measurement mechanism and free form surface, the hypotelorism of anti-locking apparatus and free form surface.

A kind of method that adopts said apparatus to measure normal vector of arbitrary point of free-form surface is characterized in that: comprise the following steps:

Step 1: move the exterior mechanical process arm by Digit Control Machine Tool, make four measurement of angle assemblies of measurement mechanism towards free form surface, and exterior mechanical process arm central axis is by the tested point on free form surface;

Step 2: handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to the tested point direction, the spherical contact of four measurement of angle assemblies contacts with free form surface respectively, and spherical contact slides on free form surface, after the exterior mechanical process arm moves to predeterminated position along its central shaft alignment free form surface direction, manipulation exterior mechanical process arm away from the return motion of free form surface direction, disengages four spherical contacts and free form surface along its central shaft alignment; Angular transducer in the measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and pass to the coordinate that digital control system calculates spherical contact and free form surface contact point, respectively the relative spherical contact in two groups of positions and the coordinate of free form surface contact point are carried out curve fitting, obtain the curve of two quadratures on free form surface, article two, the intersection point of orthogonal curvilinear overlaps with tested point on free form surface, and each curve all is in respectively on a plane;

Step 3: in any curve residing plane that step 2 obtains, calculate the normal vector at the place of tested point on this curve, take two relative measurement of angle assemblies obtaining this curve in step 2 as first group of measurement of angle assembly, remaining two relative measurement of angle assemblies is second group of measurement of angle assembly;

step 4: deflection exterior mechanical process arm, the normal vector that obtains in exterior mechanical process arm central axis and step 3 is overlapped, and then handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to the tested point direction, the spherical contact of second group of measurement of angle assembly contacts with free form surface respectively, and spherical contact slides on free form surface, angular transducer in second group of measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and pass to the coordinate that digital control system calculates spherical contact and free form surface contact point, coordinate to second group of measurement of angle assembly and free form surface contact point carries out curve fitting, obtain one with step 3 in the curve of the orthogonal curve that adopts, the curve that obtains is crossed tested point, and be on a plane,

Step 5: in the curve that step 4 obtains residing plane, the normal vector at tested point place on the curve that calculation procedure 4 obtains is the normal vector of tested point on free form surface.

Beneficial effect

The present invention contacts with free form surface by the measurement of angle assembly of four pairwise orthogonals, match obtains two orthogonal curvilinears, article two, orthogonal curvilinear and exterior mechanical process arm central axis form orthogonal plane, by asking for curve at the normal vector at tested point place in orthogonal plane, orthogonal plane is carried out angle modification, ask at last revised orthogonal plane and free form surface intersection at the normal vector at tested point place, be the normal vector at the place of tested point on free form surface.This method adopts curve to replace surface fitting, and relatively comparatively simple with Surface Fitting, measurement data points is less, has saved the complex process of surface fitting, and precision also can satisfy actual requirement when measuring curved surface of high curvature, is convenient to application.Owing to adopting contact measurement method, the characteristics such as the data acquisition result is accurate, and certainty of measurement is higher, and can effectively reduce installation cost, has simple in structure, flexible operation, and reliability is high, production cost is low.

Description of drawings

Fig. 1: the front view that installs in the present invention;

Fig. 2: the upward view that installs in the present invention;

Fig. 3: the O-O cutaway view that installs in the present invention;

Fig. 4: measurement of angle mechanism structure schematic diagram;

Fig. 5: the side view of measurement of angle mechanism;

Fig. 6: the structural representation of upper cartridge body;

Fig. 7: the structural representation of lower box body;

Fig. 8: the Mathematical Modeling schematic diagram of measuring normal vector in embodiment;

Wherein: 1, measurement of angle mechanism; 2, connect base; 3, feeler lever limiting plate; 4, low coverage touching alarm; 5, lower box body; 6, upper cartridge body; 7, reset tension spring; 8, feeler lever; 9, connecting rod; 10, spherical contact; 11, angular transducer.

The specific embodiment

Below in conjunction with specific embodiment, the present invention is described.

Embodiment:

The present embodiment is the normal vector of riveting point to be bored on the survey aircraft covering, because the present generation aircraft covering mostly is freely complex-curved, for not only rapidly quick but also accurately measure the normal vector of riveting point to be bored, adopt the measurement mechanism of the present invention's proposition to measure in the present embodiment.

With reference to accompanying drawing 1, this device comprises a main body fixation kit and four measurement of angle mechanisms 1.The main body fixation kit forms by connecting base 2 and box body, box body is divided into upper cartridge body 6 and lower box body 5, upper cartridge body 6 and lower box body 5 are bolted to connection, connect base 2 one sides and upper cartridge body 6 and be bolted to connection, connection base 2 opposite sides are bolted with the exterior mechanical process arm and are connected.

With reference to accompanying drawing 2, accompanying drawing 6 and accompanying drawing 7, be evenly equipped with four radial grooves in the side of box body, and four radial grooves are crossing distribution, radial groove be used for to be placed feeler lever 8, connecting rod 9 and the spherical contact 10 of measurement of angle mechanism 1, in box body inside, four groups of spaces are arranged also, be respectively used to place the angular transducer 11 of four measurement of angle mechanisms 1.

With reference to accompanying drawing 3, accompanying drawing 4 and accompanying drawing 5, each measurement of angle mechanism 1 comprises angular transducer 11, feeler lever 8 and spherical contact 10, feeler lever 8 outer ends are connected with spherical contact 10 by connecting rod 9, feeler lever 8 other ends are fixedly connected with the measurement axle of angular transducer 11, and feeler lever 8 can drive angular transducer and measure the axle rotation, and angular transducer 11 is measured feeler levers 8 and driven the angle that angular transducers measurement axles rotate.Spherical contact 10 is the rigidity spheroid, and spherome surface is smooth, and frictional resistance is little, and during measurement, spherical contact 10 contacts with covering and relative sliding.

With reference to accompanying drawing 1, accompanying drawing 2 and accompanying drawing 3, bottom at lower box body 5 also is equipped with feeler lever limiting plate 3, the platy structure of symmetry centered by feeler lever limiting plate 3, and the central axis of feeler lever limiting plate 3 and exterior mechanical process arm central axis conllinear, feeler lever limiting plate 3 is used for determining the initial outer drift angle of feeler lever.Also be fixed with low coverage touching alarm 4 at feeler lever limiting plate 3, be used for the distance of measurement mechanism and Skinning Surfaces, and give the alarm when setting value in the distance of measurement mechanism and Skinning Surfaces, prevent the hypotelorism of locking apparatus and Skinning Surfaces.

Four measurement of angle mechanisms 1 are fixedly connected with box body by angular transducer 11 separately, and four feeler levers 8 all contact with feeler lever limiting plate 3, so that determine the initial outer drift angle of feeler lever.Four feeler levers also are connected with box body by reset tension spring 7 in an end end that is connected with angular transducer separately, and the effect of reset tension spring 7 is in installing motion process, with feeler lever drift angle degree outside larger outer drift angle degree returns to initially.

For the accuracy that assurance device is measured, need to guarantee in the assembling process of device following some: 1, the angular transducer measurement axle of relative two the measurement of angle mechanisms in position is parallel; 2, to measure axle vertical for the angular transducer of adjacent two the measurement of angle mechanisms in position; The centre of sphere line of the spherical contact of 3, the centre of sphere line of the spherical contact of relative two the measurement of angle mechanisms in position is relative with two other position measurement of angle mechanism is vertical, and two centre of sphere lines and exterior mechanical process arm central axis all intersect.

What measure due to itself is exactly arbitrfary point normal vector on free form surface, so in four measurement of angle mechanisms, whether angular transducer measurement axle is identical with the distance of the spherical contact centre of sphere separately, not impact of accuracy on measurement device, but for the ease of determining spherical contact and covering contact point coordinate in digital control system, so the angular transducer measurement axle of four measurement of angle mechanisms is identical with the distance of the spherical contact centre of sphere in the present embodiment.

Adopt the normal vector of riveting point to be bored on said apparatus survey aircraft covering, comprise the following steps:

Step 1: move the exterior mechanical process arm by Digit Control Machine Tool, make four measurement of angle assemblies 1 of measurement mechanism towards Skinning Surfaces, and exterior mechanical process arm central axis is by the riveting point to be bored on Skinning Surfaces;

step 2: handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to riveting point direction to be bored, the spherical contact of four measurement of angle assemblies contacts with Skinning Surfaces respectively, and spherical contact slides on Skinning Surfaces, when the exterior mechanical process arm moves to predeterminated position along its central shaft alignment Skinning Surfaces direction, after in the present embodiment, the low coverage of measurement mechanism touching alarm is 5mm from the distance of Skinning Surfaces, handle the exterior mechanical process arm along its central shaft alignment away from the return motion of Skinning Surfaces direction, four spherical contacts and Skinning Surfaces are disengaged, angular transducer in the measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and passes to the coordinate that digital control system calculates spherical contact and Skinning Surfaces contact point.

The coordinate of spherical contact and Skinning Surfaces contact point resolves process in detail: set up the space law of measurement mechanism to measuring Mathematical Modeling, as shown in Figure 8, wherein vector n represents the central axial direction of exterior mechanical process arm, orthogonal vectors n ₁, n ₂The plane at place is the contact separation face of measurement mechanism upper and lower box body, is also simultaneously that four angular transducers are measured the residing common plane of axle axis, and vector n is perpendicular to this plane, and intersection point is some O.Vector n ₁It is parallel that the angular transducer of relative with one group of position two measurement of angle mechanisms is measured the axle axis, vector n ₂It is parallel that the angular transducer of two the measurement of angle mechanisms relative with another group position is measured the axle axis.Point P ₁To P ₄Represent the centre of sphere point of the spherical contact of four feeler lever ends, two dotted lines are the geometric locus that spherical contact motion is streaked, some O on Skinning Surfaces ₁To O ₄Be respectively the measurement axle axis of four angular transducers and the focus of feeler lever axis separately.

At first, determine known quantity in Mathematical Modeling:

Be fixed on due to this measuring mechanism in the mechanical arm tail end executing agency of six coordinate industrial robots, associated movement is completed a series of measuring processes thereupon.So the locus of measurement mechanism can directly be derived by the position of robot arm end.Can determine that now the required known quantity of subsequent calculations is as follows:

1, can draw by the robot arm terminal position: four angular transducers are measured axle axis plane equation Ax+By+Cz+D=0 of living in, the coordinate (x of some O ₀, y ₀, z ₀) and vector n ₁Expression formula n ₁=(A ₁, B ₁, C ₁);

2, the size by measurement mechanism can draw: angular transducer measure axle axis and exterior mechanical process arm central axis apart from a, distance L and the spherical contact radius R of angular transducer measurement axle axis and the spherical contact centre of sphere;

3, four the feeler lever deflection angle that angular transducer records: θ _n(n=1,2,3,4).

Secondly, the unknown quantity in the derivation model:

1, exterior mechanical process arm central axis equation:

$\frac{x-x_0}{A}=\frac{y-y_0}{B}=\frac{z-z_0}{C}$

The expression formula of vector n is n=(A, B, C)

2, vector n ₂:

${\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HSA00000579453000011.png,HSA00000579453000021.png"\; state="\{\{state\}\}">n</figure-callout>}}_2=n\&times;{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">n</figure-callout>}}_1=(A,B,C)\&times;(A_1,{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">B</figure-callout>}}_1,C_1)=\left|\begin{array}{ccc}i& j& k\\ A& B& C\\ A_1& B_1& {\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">C</figure-callout>}}_1\end{array}\right|$

$=({\mathrm{BC}}_1-B_{1}C)i+(A_{1}C-{\mathrm{AC}}_1)j+({\mathrm{AB}}_1-A_{1}B)k=({\mathrm{BC}}_1-B_{1}C,A_{1}C-{\mathrm{AC}}_1,{\mathrm{AB}}_1-A_{1}B)$

3, by vector n ₂Can be P with the coordinate of an O ₁, P ₃The plane equation of ordering with O satisfies:

(BC ₁-B ₁C)x ₀+(A ₁C-AC ₁)y ₀+(AB ₁-A ₁B)z ₀+D ₁＝0

Draw D ₁=-[(BC ₁-B ₁C)x ₀+ (A ₁C-AC ₁) y ₀+ (AB ₁-A ₁B)z ₀], cross P ₁, P ₃The plane equation of ordering with O is (BC ₁-B ₁C) x+ (A ₁C-AC ₁) y+ (AB ₁-A ₁B) z-[(BC ₁-B ₁C)x ₀+ (A ₁C-AC ₁) y ₀+ (AB ₁-A ₁B)z ₀]=0

4, coordinate and four the angular transducers measurement axle axis plane equation Ax+By+Cz+D=0 of living in by an O ask an O ₁To O ₄Coordinate: with O ₁Point is established O for example ₁Point coordinates is (m ₁, n ₁, p ₁), O ₁Point is on the Ax+By+Cz+D=0 of plane, so Am ₁+ Bn ₁+ Cp ₁+ D=0; O ₁Point is a to O point distance, so $a=\sqrt{{(m_1-x_0)}^2+{(n_1-y_0)}^2+{(p_1-z_0)}^2};$ Corresponding proportion expression $\frac{m_1-x_0}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}=\frac{n_1-y_0}{{\mathrm{<figure-callout\; id="1"\; label="B"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">B</figure-callout>}}_1}=\frac{p_1-z_0}{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}.$ Simultaneous solution three formulas can obtain O ₁Point coordinates (m ₁, n ₁, p ₁).In like manner can obtain O ₂, O ₃, O ₄Coordinate.

5, the feeler lever deflection angle that is recorded by four angular transducers: θ _n(n=1,2,3,4) calculate contact centre of sphere point P ₁To P ₄Coordinate: with P ₁Point is established P for example ₁Point coordinates is (x ₁, y ₁, z ₁), P ₁Point is in plane (BC ₁-B ₁C) x+ (A ₁C-AC ₁) y+ (AB ₁-A ₁B) z-[(BC ₁-B ₁C)x ₀+ (A ₁C-AC ₁) y ₀+ (AB ₁-A ₁B)z ₀In]=0, obtain (BC ₁-B ₁C)x ₁+ (A ₁C-AC ₁) y ₁+ (AB ₁-A ₁B)z ₁-[(BC ₁-B ₁C)x ₀+ (A ₁C-AC ₁) y ₀+ (AB ₁-A ₁B)z ₀]=0P ₁To O ₁Distance be L, obtain $\sqrt{{(x_1-m_1)}^2+{(y_1-n_1)}^2+{(z_1-p_1)}^2}=L;$ By the feeler lever deflection angle theta ₁, vector n=(A, B, C), $n_{o_1{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}=(x_1-{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">m</figure-callout>}}_1,y_1-{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">n</figure-callout>}}_1,z_1-p_1)$ Obtain

$\cos {\mathrm{\&theta;}}_1=\frac{|n\&CenterDot;n_{o_1{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}|}{\left|n\right|\&CenterDot;\left|n_{o_1{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="HSA00000579453000011.png,HSA00000579453000033.png"\; state="\{\{state\}\}">p</figure-callout>}}_1}\right|}=\frac{|A\&CenterDot;(x_1-m_1)+B\&CenterDot;(y_1-n_1)+C\&CenterDot;(z_1-p_1)|}{\sqrt{A^2+{\mathrm{<figure-callout\; id="2"\; label="B"\; filenames="HSA00000579453000011.png,HSA00000579453000021.png"\; state="\{\{state\}\}">B</figure-callout>}}^2+{\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="HSA00000579453000011.png,HSA00000579453000021.png"\; state="\{\{state\}\}">C</figure-callout>}}^2}\&CenterDot;\sqrt{{(x_1-m_1)}^2+{(y_1-n_1)}^2+{(z_1-p_1)}^2}}$

Above three equatioies of simultaneous solution can be tried to achieve P ₁Point coordinates (x ₁, y ₁, z ₁), in like manner can obtain P ₂, P ₃, P ₄Point coordinates.

After obtaining respectively contact sphere centre coordinate value under different feeler levers drift angles corresponding to different time by above-mentioned steps, utilization carries out curve fitting to the relative spherical contact in two groups of positions and the coordinate of Skinning Surfaces contact point respectively based on the nurbs curve fitting process in the CATIA surface modeling, obtain the curve of two quadratures on Skinning Surfaces, article two, the intersection point of orthogonal curvilinear overlaps with riveting point to be bored on Skinning Surfaces, and each curve all is in respectively on a plane.

Step 3: in any curve residing plane that step 2 obtains, find the solution the normal vector at the place of riveting point to be bored on this curve of function calculating by calling the normal in the plane in wire frame and surface modeling module in CATIA, take two relative measurement of angle assemblies obtaining this curve in step 2 as first group of measurement of angle assembly, remaining two relative measurement of angle assemblies is second group of measurement of angle assembly;

step 4: deflection exterior mechanical process arm, the normal vector that obtains in exterior mechanical process arm central axis and step 3 is overlapped, and then handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to riveting point direction to be bored, the spherical contact of second group of measurement of angle assembly contacts with Skinning Surfaces respectively, and spherical contact slides on Skinning Surfaces, angular transducer in second group of measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and pass to the coordinate that digital control system calculates spherical contact and Skinning Surfaces contact point, and the coordinate of second group of measurement of angle assembly and Skinning Surfaces contact point is carried out curve fitting, obtain one with step 3 in the curve of the orthogonal curve that adopts, the curve that obtains is crossed riveting point to be bored, and be on a plane,

Step 5: in the curve that step 4 obtains residing plane, find the solution the normal vector at the place of riveting point to be bored on the curve that function calculating step 4 obtains by calling the normal in the plane in wire frame and surface modeling module in CATIA, be the normal vector of riveting point to be bored on Skinning Surfaces.

The spline surface that several groups of eyeballs in the present embodiment on certain model aircraft wing cover wallboard consist of is as example, the accuracy of checking the method when measuring free form surface.By a certain section in this skinpiston curved surface of robot field survey, as follows by the some bit table that draws after coordinate transform under space coordinates:

Above-mentioned 4 groups 16 eyeball positions are simulated a spline surface by the CATIA surface modeling function, get a P ₃₂As boring point to be measured, adopt the said method step to measure, because aircraft skin panel surfaces radian changes gently, in the zone among a small circle at the single brill riveting point of covering place, it is not very greatly that the curvature that the wallboard surf deform causes changes, can be similar to and regard planar structure as, so the theoretical accurate normal angle of the actual normal that calculates and curved surface is very little, be about 0.005 °, the approximate coincidence, can verify that the method is feasible in theory, result of calculation is accurate, and precision is high.

Claims (4)

1. device of measuring normal vector of arbitrary point of free-form surface is characterized in that: comprise a main body fixation kit and four measurement of angle mechanisms;

Each measurement of angle mechanism comprises angular transducer, feeler lever and spherical contact, and the feeler lever outer end is connected with spherical contact, and the feeler lever other end is measured axle with angular transducer and is fixedly connected with, and angular transducer is measured feeler lever and is driven angular transducer and measure the angle that axle rotates;

the main body fixation kit comprises connection base and box body, connecting base and box body is fixedly linked, connecting base and exterior mechanical process arm is fixedly linked, the box body side is evenly equipped with four radial grooves, four radial grooves are crossing distribution, four measurement of angle mechanisms are placed on respectively in four radial grooves, and the angular transducer by separately is fixedly connected with box body respectively, it is parallel that the angular transducer of two measurement of angle mechanisms that the position is relative is measured axle, it is vertical that the angular transducer of two measurement of angle mechanisms that the position is adjacent is measured axle, the centre of sphere line of the spherical contact of the measurement of angle mechanism that the centre of sphere line of the spherical contact of two measurement of angle mechanisms that the position is relative is relative with two other position is vertical, and two centre of sphere line and exterior mechanical process arm central axis all intersect, the feeler lever of each measurement of angle mechanism also is connected with box body by reset tension spring in the end end that it is connected with angular transducer.

2. a kind of device of measuring normal vector of arbitrary point of free-form surface according to claim 1, it is characterized in that: also include the feeler lever limiting plate, the platy structure of symmetry centered by described feeler lever limiting plate, be fixed on box body back to a side that connects base, and feeler lever limiting plate central axis and exterior mechanical process arm central axis conllinear, the feeler lever limiting plate is used for determining the initial outer drift angle of feeler lever.

3. a kind of device of measuring normal vector of arbitrary point of free-form surface according to claim 2, it is characterized in that: also include low coverage touching alarm, low coverage touching alarm is fixed on the feeler lever limiting plate, the distance that is used for measurement mechanism and free form surface, and give the alarm during less than setting value in the distance of measurement mechanism and free form surface, the hypotelorism of anti-locking apparatus and free form surface.

4. one kind is adopted the method for measurement device normal vector of arbitrary point of free-form surface as claimed in claim 1, it is characterized in that: comprise the following steps:

Step 1: move the exterior mechanical process arm by Digit Control Machine Tool, make four measurement of angle assemblies of measurement mechanism towards free form surface, and exterior mechanical process arm central axis is by the tested point on free form surface;

Step 2: handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to the tested point direction, the spherical contact of four measurement of angle assemblies contacts with free form surface respectively, and spherical contact slides on free form surface, after the exterior mechanical process arm moves to predeterminated position along its central shaft alignment free form surface direction, manipulation exterior mechanical process arm away from the return motion of free form surface direction, disengages four spherical contacts and free form surface along its central shaft alignment; Angular transducer in the measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and pass to the coordinate that digital control system calculates spherical contact and free form surface contact point, respectively the relative spherical contact in two groups of positions and the coordinate of free form surface contact point are carried out curve fitting, obtain the curve of two quadratures on free form surface, article two, the intersection point of orthogonal curvilinear overlaps with tested point on free form surface, and each curve all is in respectively on a plane;

Step 3: in any curve residing plane that step 2 obtains, calculate the normal vector at the place of tested point on this curve, take two relative measurement of angle assemblies obtaining this curve in step 2 as first group of measurement of angle assembly, remaining two relative measurement of angle assemblies is second group of measurement of angle assembly;

step 4: deflection exterior mechanical process arm, the normal vector that obtains in exterior mechanical process arm central axis and step 3 is overlapped, and then handle the exterior mechanical process arm and move along its central axis, measurement mechanism is moved to the tested point direction, the spherical contact of second group of measurement of angle assembly contacts with free form surface respectively, and spherical contact slides on free form surface, angular transducer in second group of measurement of angle assembly is measured the deflection angle of feeler lever in motion process in real time, and pass to the coordinate that digital control system calculates spherical contact and free form surface contact point, coordinate to second group of measurement of angle assembly and free form surface contact point carries out curve fitting, obtain one with step 3 in the curve of the orthogonal curve that adopts, the curve that obtains is crossed tested point, and be on a plane,

Step 5: in the curve that step 4 obtains residing plane, the normal vector at tested point place on the curve that calculation procedure 4 obtains is the normal vector of tested point on free form surface.

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