A kind of ship plank formed precision online test method
Technical field
The present invention relates to the formed precision online test methods in a kind of ship plank process.Belong to shipbuilding skill
Art and field of optical measurements.
Background technique
Bent plate molding especially double-parabolic slab forming technique be in current world's shipbuilding industry it is a kind of it is technical it is strong, difficulty is big,
Processing technology more than influence factor.How to detect in process and differentiates the shape for being processed hull curve plate and target bent plate
Error is current shipbuilding industry problem in the urgent need to address, and how quickly, accurately acquisition type face data is the key that solve the problems, such as.
Shipyard relies primarily on experienced worker by way of card template, sample case to realize at present.But this method is only
Low volume data on rib bit line is only obtained, and precision is decided by template, sample case precision, and most of template, sample case are wooden material
Biggish deformation can occur for material, such as weather affected by environment, and error is larger.Later application irony adjustable sample plate, but it is same
The eyes range estimation deviation by people is needed, precision not can guarantee, and be provided with obstacle for subsequent shipbuilding precision controlling.
With the development of computer technology and photoelectric technology, the detection of area of computer aided deck of boat curved surface forming has become one
Important developing direction.For decades, domestic and international many experts and scholars are dedicated to the research and development of novel detection technique and equipment.
Domestic contrast is representational to be had: (1) Dalian University of Technology, Dalian New Shipbuilding Heavy Industries Co., Ltd., Tsing-Hua University are big
The units such as and BJ University of Aeronautics & Astronautics, it is molding to outside plate after ship hull plate machine-shaping automatic testing method, processing
Automatic discrimination has carried out relevant research and has achieved certain achievement, but from engineering practical application there are also very big one section away from
From;(2) Wuhan University of Technology and Shandong is large stands on plate digital control cold bending equipment, uses guide rail and laser point measurement method,
Panel Data is obtained, data acquisition speed is slower.
Foreign countries are more representational to be had: (1) J S Park, J G Skin, K the H Ko of Seoul National University uses three coordinates
Measuring instrument (CMM) measures the deck of boat, measurement accuracy is high, can approximation obtain deck of boat boundary, the data of the characteristic points such as angle point.
But there is numerous disadvantages: (a) measurement process needs a large amount of manual operation, causes measurement efficiency low;(b) use of CMM
Field environmental condition is required high;(c) expansion of CMM measurement range needs to increase many costs etc..
Summary of the invention
To overcome the shortcomings of prior art and defect, the present invention provides the formed precision in a kind of ship plank process
Online test method quickly can accurately obtain deck of boat formed precision data.
To achieve the goals above, the technical solution of the present invention is as follows: a kind of formed precision in ship plank process
Online test method, it is characterised in that method includes the following steps: A, using three-dimensional holder drive laser range finder scan ship
Plate surface;B, the distance value of acquisition is converted into a coordinate;C, point cloud layering denoising, fairing, are fitted to face;D, deck of boat table is shot
Face texture photo, and assignment is managed for point moire;E, fitting face boundary is corrected based on texture variations;It F, will fitting face and deck of boat theory
Face matching;G, deviation is calculated and is shown.For the present invention compared with traditional measurement method, speed is fast, precision is high, adaptable.
According to a particular embodiment of the invention, the formed precision online test method specifically includes the following steps:
A, laser range finder is driven to scan deck of boat surface using three-dimensional holder, scanning element spacing d and line space l use software
Control, d and l are adjustable;
B, the distance value of acquisition is converted to and puts coordinate under scanning device fixed coordinate system, and establish the rope of all the points coordinate
Draw value, each point has former distance value, coordinate number and coordinate value, i-th of point PiDescription are as follows:
Pi(xi,yi,zi,si,ui,vi)
Wherein x, y, z are coordinate value, siFor distance value, u, v are that (scanning process is progressive scan, u, v difference to index value
Row where expression point and serial number in each row), i=1,2,3 ... n, n are total count.
C, point cloud layering denoising, the fairing formed above-mentioned point, be fitted to face: setting bent plate with a thickness of t, k is threshold coefficient,
Delete the point for being greater than threshold value in continuity point cloud apart from value mutation, then:
Wherein, 1 retains for the point, and 0 be the point is noise;
Fairing and fitting surface are carried out to cloud using classical least square method;
D, deck of boat surface texture photo is shot, and manages assignment for point moire: setting any pixel coordinate of texture photo are as follows:
0≤r,g,b≤255,0≤α≤1
By photo texture mapping to scanning device fixed coordinate system, by coordinate value is corresponding or closest approach assignment texture coordinate,
It is indicated with texture value invocation point are as follows:
Pi(xi,yi,zi,si,ui,vi,wi);
E, fitting face boundary is corrected based on texture variations: being defined according to texture value, continuous two o'clock texture variations are as follows:
Deck of boat surface characteristics sets texture variations threshold θ, then:
Wherein, 1 point retains, and 0 point is noise;
Noise is removed, quadratic interpolation fitting is carried out to face boundary is retained, obtains exact boundary;
F, fitting face is matched with deck of boat theory face: from Ship Design system output ship Theoretical Design curved surface as benchmark
Fitting face is carried out slightly matching based on bounding box and the accurate matching based on ICP algorithm with theoretical curved surface by curved surface;
G, the deviation between the fitting face all the points and theory after matching is completed, as deck of boat formed precision are calculated
Value.
Scanning element spacing d and line space l uses software control in above-mentioned steps A, and d and l is adjustable.
It uses in above-mentioned steps C and is denoised automatically apart from mutation value.
In above-mentioned steps D texture photo and give coordinate points assignment.
Exact boundary is obtained based on texture coordinate changes of threshold in above-mentioned steps D.
The present invention uses based on range measurement principle and is converted to coordinate value, and then obtains outside plate geometry profile, is based on measurement plate
It is preliminary to obtain outer template face data with the extraneous automatic denoising of distance mutation in one direction, in the variation based on texture
Obtain outside plate exact boundary and data.Compared with traditional template, sample case acquisition method and other optically detecting methods, there is speed
The features such as degree is fast, precision is high, adaptable.Application of the invention be realize the automation of bent plate processing technology key link it
One.
Detailed description of the invention
Fig. 1 is the flow chart of ship plank formed precision online test method.
Fig. 2 is the relational graph for measuring distance and coordinate system transformation.
Specific embodiment
It include: surveying vessel board mount 1 in figure, ship plank 2 to be measured, scanning device pedestal 3, Laser Distance Measuring Equipment 4, camera
5。
Below with reference to the flow chart of Fig. 1 Curved dectection method, a specific embodiment of the invention is further described.
1) the three-dimensional holder of application drives laser range finder to scan deck of boat surface, and scanning element spacing d and line space l use software
Control, d and l are adjustable;
2) distance value of acquisition is converted to and puts coordinate under scanning device fixed coordinate system, and establish the rope of all the points coordinate
Draw value, each point has former distance value, coordinate number and coordinate value, i-th of point PiDescription are as follows:
Pi(xi,yi,zi,si,ui,vi)
Wherein x, y, z are coordinate value, siFor distance value, u, v are index value, and i=1,2,3 ... n, n are total points.Distance
Value siFor laser range finder range reading, if certain point i distance is s, due to rangefinder and three-dimensional holder have fixed position and
Posture relationship, then its coordinate value in three-dimensional holder coordinate system is Ps (ψ i, φ i, s), and ψ, φ are that rangefinder is measuring the point
The horizontal and vertical pivot angle of Shi Sanwei holder;If the transformation matrix of three-dimensional holder to global fixed coordinate system is T, then i point is in fixation
The coordinate value of coordinate system is Pi (xi, yi, zi)=Ps (ψ i, φ i, s) T.
3) point cloud layering denoising, the fairing formed above-mentioned point, be fitted to face: setting bent plate with a thickness of t, k is threshold coefficient,
Delete the point for being greater than threshold value in continuity point cloud apart from value mutation, then:
Wherein, 1 retains for the point, and 0 be the point is noise.
Fairing and fitting surface are carried out to cloud using classical least square method.
4) deck of boat surface texture photo is shot, and manages assignment for point moire: setting any pixel coordinate of texture photo are as follows:
0≤r,g,b≤255,0≤α≤1
By photo texture mapping to scanning device fixed coordinate system, by coordinate value correspondence or closest approach assignment texture coordinate, α
It is intensity value, the integrated regulation parameter of grain brightness.Then, the point with texture value indicates are as follows:
Pi(xi,yi,zi,si,ui,vi,wi)
5) fitting face boundary is corrected based on texture variations: being defined according to texture value, continuous two o'clock texture variations are as follows:
Deck of boat surface characteristics sets texture variations threshold θ, then:
Wherein, 1 point retains, and 0 point is noise.
Quadratic interpolation fitting is carried out to face boundary is retained, obtains exact boundary
6) fitting face is matched with deck of boat theory face: from Ship Design system output ship Theoretical Design curved surface as benchmark
Fitting face is carried out slightly matching based on bounding box and the accurate matching based on ICP algorithm with theoretical curved surface by curved surface;
7) deviation between the fitting face all the points and theory after matching is completed, as deck of boat formed precision are calculated
Value.