For the method measuring the pose of the columnar object with circular cambered surface
Technical field
The present invention relates to object fields of measurement, more particularly, to a kind of for measuring the column with circular cambered surface
The method of the pose of body.
Background technology
Have the columnar object (such as cylindrical object) of circular cambered surface be most basic in commercial production, the frequency of occurrences
One of high parts, are widely applied in productive life.Set and Positioning during cylindrical object production and processing is equal traditionally
Using holder or the mode of mould location, the precision of pose ensure that.But it is poor with linearity for some cylindricity
Cylindrical object, by the way of holder or mould location, do not ensure that the pose accuracy in its each cross section;Due to
The shape particularity of cylindrical object elongate, is also easily generated when bearing the processing technique such as such as unilateral welding, unilateral punching
The thermal deformations such as warpage, the location by fixture is difficult to ensure the positioning precision of cylindrical object the most merely, to production and processing band
Come difficult.Thus, traditionally for processing technique and the yielding processing technique of high-precision requirement of elongated cylindrical object
Had been manually done by workman.Such as, the arc stud welding processing of Technique in Boiler Membrane Water Cooled Wall bank of tubes, its process produced is the most loaded down with trivial details, effect
Rate is low, and the working environment of workers is severe, and labor intensity is big, and personal safety can not get ensureing.
In recent years, along with progress and the economic fast development of Chinese science and technology, robotics constantly improves, industrial machine
The application of people is more and more extensive so that in the dimensional instability of elongated cylindrical object is processed, applied robot replaces workman
Become possibility, and the pose that robot can obtain cylindrical object in real time is to use industrial robot to replace workman to give birth to
The prerequisite produced.At present, robot Measuring Object many employings vision sensor, although this mode ensure that the essence of measurement
Degree, can be relatively costly, and the time complexity of recognizer is higher, and for cylindrical object, utilizes complicated vision
Sensor identify pose it is not necessary that.The production that can carry out cylindrical object for guarantee robot the most reliably adds
How work, work out reliable cylindrical object pose measurement simple and quick, practical under conditions of reducing cost to greatest extent
Method the most just becomes particularly important.
Summary of the invention
The present invention proposes a kind of method of spatial pose identifying the columnar object with circular cambered surface rapidly and accurately,
And the method realize low cost, it is only necessary to linear laser two-dimensional measurement sensor can realize.
According to an aspect of the invention, it is proposed that the side of a kind of pose for measuring the columnar object with circular cambered surface
Method, the method includes:
Step 101, uses linear laser two-dimensional measurement sensor measurement to obtain multiple number of contours strong point, wherein, with laser
The cross section that bundle is launched is xoy plane, and the axis of described circular cambered surface is not parallel to described xoy plane;
Step 102, carries out ellipse fitting based on the plurality of outline data point, identifies at least one elliptic arc;
Step 103, for each elliptic arc identified, is pointed to the outline data point in the middle part of this elliptic arc and carries out ellipse
Matching, based on the absolute Euclidean distance between the oval week that the number of contours strong point and matching being positioned at this elliptic arc front and rear obtains
Screen out the error dot in the number of contours strong point being positioned at this elliptic arc front and rear;
Step 104, for each elliptic arc identified, carries out ellipse to outline data point remaining after screening out error dot
Matching, to determine corresponding oval characteristic parameter, described characteristic parameter include elliptical center position in described xoy plane,
Oval major semiaxis length a, oval semi-minor axis length b, oval incline direction;
Step 105, based on described characteristic parameter, obtains the position of the columnar object section corresponding with each elliptic arc identified
Appearance.
Optionally, described step 102 includes:
If measuring in a step 101 and obtaining number number of contours strong point, it is followed successively by p (x1,y1)、p(x2,y2)、…、p
(xnumber,ynumber);
Step A1, makes i=1, vertex=1, flag=0, enters step B1;
Step B1, carries out ellipse fitting to i to i+num-1 num outline data point altogether, enters step C1;
Step C1, was currently participated in num number of contours strong point of ellipse fitting each and between corresponding oval week
Definitely Euclidean distance errorj, j=i, i+1 ..., i+num-1, enter step D1;
Step D1, if currently participate between num number of contours strong point of ellipse fitting and corresponding ellipse week is the most European
Distance errorj, j=i, i+1 ..., i+num-1 is all less than measurement error threshold value error_measure, then enter step E1, no
Then enter step F1;
Step E1, it is believed that this num number of contours strong point is respectively positioned on same elliptic arc, and if flag=0, then enter one
Step record p (xi,yi) be starting point i.e. start (the vertex)=i of this elliptic arc and flag=1 is set, enter step G1;
Step F1, it is believed that this num number of contours strong point is not positioned on same elliptic arc, and if flag=1, then enter one
Step record p (xi+num-2,yi+num-2) be terminal i.e. finish (the vertex)=i+num-2 of this elliptic arc and vertex is set
=vertex+1 and flag=0, enters step G1;
Step G1, if i+num-1=number, then terminates;I=i+1 is otherwise set, returns to step B1, to next group
Num outline data point is identified, until i+num-1=number.
Alternatively,R is the radius that described arc of circle face is corresponding,Line_width is the live width of every Shu Jiguang, width
For overall measurement width, distance is the laser source point friendship to described xoy plane with the axis of circular cambered surface of described sensor
Distance between point, Slope is the slope of the laser beam outermost profile of described sensor emission.
Alternatively, any n outline data point is carried out ellipse fitting to include:
Use method of least square (such as non-linear least square), based on making following objective functions J minimum obtain oval existing
Central coordinate of circle (x in described xoy plane0_n, y0_n), major semiaxis length an, semi-minor axis length bn, the angle theta of major axis and x-axisn:
WhereinBy x0_n
Initial value be assigned to the x coordinate value in n number of contours strong point with the data point of maximum y-coordinate value, by y0_nInitial value be assigned to n
The y-coordinate value of the data point in number of contours strong point with maximum y-coordinate value deducts the radius r that described arc of circle face is corresponding, by an
And bnInitial value be all assigned to r, by θnInitial value be assigned to 0.
Alternatively, any number of contours strong point p (x is obtained based on following formulak,yk) and corresponding oval week between absolute Euclidean distance
errork:
Wherein,(x0_n,
y0_n) it is oval central coordinate of circle in described xoy plane, anFor major semiaxis length, bnFor semi-minor axis length, θnFor major axis and x
The angle of axle.
Alternatively, elliptic arc front portion is at the 15%~25% of this elliptic arc starting point to this elliptic arc, elliptic arc rear portion
For terminal to this elliptic arc at the 75%~85% of this elliptic arc.
Alternatively, at step 104, first outline data point remaining after screening out error dot is smoothed and homogenization
Process, then the data point of smoothedization and Homogenization Treatments is carried out ellipse fitting, to determine corresponding oval characteristic parameter.
Alternatively, described smoothing includes: choose spectral window this elliptic arc a width of remaining number of contours strong point 30%,
According to local regression method, choose the data point of the roomy small data quantity of spectral window successively, use method of least square (such as to weight line
Property least square) obtain making number of contours strong point second-order polynomial curve of point set optimal solution in filtering window width.
Alternatively, described homogenization includes: calculate the maximum of the x coordinate value at the number of contours strong point after smoothing techniques
xmaxWith minima xmin, at xmaxWith minima xminBetween be uniformly arranged new x coordinate value at a predetermined interval, use spline interpolation to obtain
To the y-coordinate value that new x coordinate value is corresponding.
Alternatively, the method also includes: moves described sensor along the z-axis direction vertical with described xoy plane and again holds
Row step 101~105, until completing the measurement to the columnar object described in whole with circular cambered surface.
It is an advantage of the current invention that: simply utilize the linear laser two-dimensional measurement sensor of low cost, by the survey of two dimension
Amount data, can quickly recognize the profile of circular cambered surface measuring cross section cylindrical object (such as cylindrical parts), and according to
The oval feature parameter of this profile obtains the spatial pose of the columnar object section of correspondence.The application present invention can measure arbitrary dimension
There is the spatial pose of the columnar object of circular cambered surface, such as, can measure many with the spatial pose of cylindrical object simultaneously.This
Bright also have reproducible, the advantage of strong interference immunity, it is possible to get rid of the disappearance of measurement data, measurement result is caused by saltus step
Impact, and the impact that measurement is caused by other shaped objects in the range of measurement can be discharged.
Accompanying drawing explanation
By combining accompanying drawing, exemplary embodiment of the invention is described in more detail, the present invention above-mentioned and its
Its purpose, feature and advantage will be apparent from, wherein, in exemplary embodiment of the invention, and identical reference number
Typically represent same parts.
Fig. 1 shows the columnar object for measurement with circular cambered surface according to one exemplary embodiment of the present invention
The method flow diagram of pose.
Fig. 2 shows the rough examination schematic diagram of the data point according to one exemplary embodiment of the present invention.
Fig. 3 shows the pose schematic diagram of the axis of the circular cambered surface according to one exemplary embodiment of the present invention.
Detailed description of the invention
It is more fully described the preferred embodiment of the present invention below with reference to accompanying drawings.Although accompanying drawing shows the present invention
Preferred implementation, however, it is to be appreciated that may be realized in various forms the present invention and the embodiment party that should not illustrated here
Formula is limited.On the contrary, it is provided that these embodiments are to make the present invention more thorough and complete, and can be by the present invention's
Scope intactly conveys to those skilled in the art.
A kind of method that the invention discloses pose for measuring the columnar object with circular cambered surface, the method bag
Include:
Step 101, uses linear laser two-dimensional measurement sensor measurement to obtain multiple number of contours strong point, wherein, with laser
The cross section that bundle is launched is xoy plane, and the axis of described circular cambered surface is not parallel to described xoy plane;
Step 102, carries out ellipse fitting based on the plurality of outline data point, identifies at least one elliptic arc;
Step 103, for each elliptic arc identified, is pointed to the outline data point in the middle part of this elliptic arc and carries out ellipse
Matching, based on the absolute Euclidean distance between the oval week that the number of contours strong point and matching being positioned at this elliptic arc front and rear obtains
Screen out the error dot in the number of contours strong point being positioned at this elliptic arc front and rear;
Step 104, for each elliptic arc identified, carries out ellipse to outline data point remaining after screening out error dot
Matching, to determine corresponding oval characteristic parameter, described characteristic parameter include elliptical center position in described xoy plane,
Oval major semiaxis length a, oval semi-minor axis length b, oval incline direction;
Step 105, based on described characteristic parameter, obtains the position of the columnar object section corresponding with each elliptic arc identified
Appearance.
Fig. 1 shows the columnar object for measurement with circular cambered surface according to one exemplary embodiment of the present invention
The flow chart of method of pose.
Step 1: set up two-dimensional coordinate system
Can be with the cross section of radiating laser beams for xoy plane, wherein it is possible to the lasing light emitter of linear laser dimension sensor
Point is zero, can set up left hand rectangular coordinate system with the direction of laser beam centre ray emission for y-axis negative direction.
Fig. 2 shows xoy plane.
Step 2: use linear laser two-dimensional measurement sensor to measure in real time
Can refresh and measuring command by sending to sensor, to obtain real-time measuring data.Additionally, circle also can be inputted
The size of shape cambered surface and measurement distance, and calculate laser linewidth and single identification data volume.
Input data can include that the laser source point of radius r corresponding to the arc of circle face of columnar object and sensor is to institute
Distance distance between the intersection point of the axis stating xoy plane and circular cambered surface.
Can set when the total quantity at the number of contours strong point that pre-test obtains depends on as number, its coordinate in xoy plane
Secondary for p (x1,y1)、p(x2,y2)、…、p(xnumber,ynumber).The line that sensor projects on object can be obtained according to following formula
The scope of property laser, i.e. overall measurement width width:
Wherein Slope is the slope of laser beam outermost profile of described sensor emission, originally shows
Slope=2.6 in example embodiment.
Obtain live width line_width of every Shu Jiguang further:
Calculating single identification data volume num:
It should be noted that ifResult be not integer, can root
According to needs, it is rounded, the most up or down or round.
Step 3: identify roughly the number of contours strong point being positioned on elliptic arc
Step A1, can make i=1, vertex=1, flag=0, enters step B1.
Step B1, can carry out ellipse fitting to i to i+num-1 num outline data point altogether.Specifically, can use
Nonlinear least square method, based on making following objective functions J minimum obtain oval central coordinate of circle in described xoy plane
(x0_num, y0_num), major semiaxis length anum, semi-minor axis length bnum, the angle theta of major axis and x-axisnum:
Wherein
Can be by x0_numInitial value be assigned to the x coordinate value in n number of contours strong point with the data point of maximum y-coordinate value, by y0_num's
It is corresponding that the y-coordinate value of the data point that initial value is assigned in n number of contours strong point to have maximum y-coordinate value deducts described arc of circle face
Radius r, by anumAnd bnumInitial value be all assigned to r, the initial value of θ is assigned to 0.
Then step C1 can be entered.
Step C1, can currently be participated in each and corresponding oval week in num number of contours strong point of ellipse fitting
Between absolute Euclidean distance errorj, j=i, i+1 ..., i+num-1.Specifically, error can be obtained based on following formulaj:
Wherein,
Then step D1 can be entered.
Step D1, if currently participate between num number of contours strong point of ellipse fitting and corresponding ellipse week is the most European
Distance errorj, j=i, i+1 ..., i+num-1 is all less than measurement error threshold value error_measure, then enter step E1, no
Then enter step F1;
Step E1, it is believed that this num number of contours strong point is respectively positioned on same elliptic arc, and if flag=0, then
Record p (x furtheri,yi) be starting point i.e. start (the vertex)=i of this elliptic arc and flag=1 is set, then can enter
Enter step G1;
Step F1, it is believed that this num number of contours strong point is not positioned on same elliptic arc, and if flag=1, then
Record p (x furtheri+num-2,yi+num-2) be terminal i.e. finish (the vertex)=i+num-2 of this elliptic arc and arrange
Vertex=vertex+1 and flag=0, then can enter step G1;
Step G1, if i+num-1=number, then terminates;I=i+1 is otherwise set, returns to step B1, to next group
Num outline data point is identified, until i+num-1=number.
Fig. 2 shows the rough examination schematic diagram of the data point according to one exemplary embodiment of the present invention..
Step 4: accurately screen out the error dot in each elliptic arc
Can the data point of 60% in the middle part of this elliptic arc, it is carried out the ellipse fitting (step that such as, can refer in step 3
Rapid B1), it is judged that before this elliptic arc in the middle of 20% part and the data point of rear 20% part each point with simulate oval absolute
Euclidean distance (such as, can refer to step C1 in step 3 and calculates absolute Euclidean distance).If certain data point pair calculated
The absolute Euclidean distance answered exceedes default error threshold, such as error_measure, then this data point is given up, thus realizes accurately
Screen out.
Step 5: carry out ellipse fitting for each elliptic arc after fine screen
Before carrying out ellipse fitting, can first the data point after fine screen be smoothed and Homogenization Treatments.
Described smoothing may include that the 30% of the remaining number of contours strong point choosing spectral window this elliptic arc a width of, root
According to local regression method, choose the data point of the roomy small data quantity of spectral window successively, use weighted linear method of least square to obtain
Make number of contours strong point second-order polynomial curve of point set optimal solution in filtering window width, thus realize smoothing.
Described homogenization may include that the maximum x of the x coordinate value at the number of contours strong point after calculating smoothing techniquesmaxWith
Minima xmin, at xmaxWith minima xminBetween be uniformly arranged new x coordinate value at a predetermined interval, use spline interpolation to obtain newly
Y-coordinate value corresponding to x coordinate value, thus realize homogenization.
Then the data point after smoothing and Homogenization Treatments is carried out ellipse fitting.Specifically can refer to above-mentioned steps 3
Approximating method in step B1, to determine corresponding oval characteristic parameter.Described characteristic parameter includes that elliptical center is at described xoy
Position in plane (can be by oval center of circle coordinate (x y) represents) in described xoy plane, oval major semiaxis length
A, oval semi-minor axis length b, oval incline direction (can represent by the angle theta of transverse Yu x-axis).This area skill
Art personnel may be used without other any suitable methods and realize ellipse fitting.
Step 6: obtain the pose of the columnar object section with circular cambered surface corresponding with each elliptic arc identified
Real radius r of circular cambered surface can be obtained according to oval semi-minor axis length breal;Transverse inclination angle theta is circle
The projection in xoy plane of the axis of shape cambered surface and the angle of x-axis;Axis and the z-axis of circular cambered surface can be obtained according to following formula
Angle, wherein z-axis and x-axis, y-axis composition left hand three-dimensional cartesian coordinate system:
Due to the characteristic of circular cambered surface, its angle being rotated about axis need not consider, therefore solves above-mentioned five features ginseng
Number i.e. can determine that the pose of this circle cambered surface section.Circular cambered surface position on this columnar object is changeless, therefore, and can
Pose based on this circle cambered surface section infers the pose of the columnar object section of correspondence.
Step 7: repeated execution of steps 1~6, until completing the measurement of whole columnar object
Described sensor can be moved along the z-axis direction vertical with described xoy plane and again perform above-mentioned steps 2~6, directly
To the measurement completed the columnar object described in whole with circular cambered surface.If certain move after laser source point and initial laser
Distance between source point is z, and calculate the axis of the circular cambered surface coordinate in corresponding xoy plane for (x, y), then relative to
Initial three-dimensional cartesian coordinate system, the coordinate of the intersection point of the axis of this circle cambered surface and corresponding xoy plane be (x, y, z).Fig. 3 shows
Go out the pose schematic diagram of the axis of the circular cambered surface obtained after certain is measured.
Being described above embodiments of the invention, described above is exemplary, and non-exclusive, and the most not
It is limited to disclosed each embodiment.In the case of the scope and spirit without departing from illustrated each embodiment, for this technology
For the those of ordinary skill in field, many modifications and changes will be apparent from.The selection of term used herein, it is intended to
Explain the principle of each embodiment, actual application or the improvement to the technology in market best, or make the art its
Its those of ordinary skill is understood that each embodiment disclosed herein.