CN104385053B - Normal centering method based on parallel institution - Google Patents

Abstract

The invention discloses a kind of normal centering method based on parallel institution, belong to normal direction precision controlling field.The device that the present invention uses includes parallel institution, cross slid platform, four laser displacement sensors and end effector；Parallel institution includes fixed platform and the moving platform being connected by connecting rod, and end effector is arranged on the moving platform of parallel institution, and the fixed platform of parallel institution is arranged on cross slid platform, and laser displacement sensor is arranged on end effector；The method initially sets up parallel institution coordinate system and tool coordinates system, and the distance value detected by laser displacement sensor calculates the expectation normal direction attitude that end effector should be adjusted to；In the case of ensureing virtual point of a knife point invariant position, finally obtained the adjustment amount of parallel institution by the deviation of current pose to expectation attitude against solution, thus realize normal direction centering.Device good rigidly, bearing capacity that the present invention uses are big, and its inverse arithmetic is simple, precision is high, it is possible to quickly realize the normal direction centering of end effector.

Description

Normal centering method based on parallel institution

Technical field

The present invention relates to a kind of normal centering method, be especially a kind of normal direction centering side based on parallel institution Method, belongs to normal direction precision controlling field.

Background technology

The assembling of aircraft components is mainly realized by riveting method, and riveting quality directly influences the performance of aircraft And safety, therefore riveting is a very important process procedure during aircraft manufacturing.And the system before riveting Riveting quality is played decisive role by hole precision, and especially during drilling, the axial and eyelid covering of cutter treats drilling position Normal direction keep consistent degree.Therefore, the attitude of product or cutter must be adjusted before drilling, to ensure cutter Tool axis and the vertical precision of drilling position.

At present, the riveting system normal direction pose adjustment mode when carrying out drilling is bored by automatization has product attitude and cutter Tool attitude is adjusted two ways.

In November, 2007, " aviation journal " the 06th phase, 1455-1459 page, disclose an author for the Qin Now life, Wang pomelo, 3 fast leveling algorithms of large-scale wallboard numerical control drilling riveting of luxuriant rattan, which depict a kind of logical Cross numerical control bracket and adjust product attitude, make the normal direction posture adjustment side that tool axis is consistent with the normal direction at Working position Method, the method uses three the displacement transducer detection Norma l deviation being arranged on boring and riveting machine unit head, as According to calculating bracket, each adjusts the adjustment amount of axle, thus realizes the purpose of normal direction centering, and it is disadvantageous in that Aircraft components volume is the hugest, and structure is complicated, adjusts relatively difficult, adjusts limited extent, right The rigidity of structure of numerical control bracket and control accuracy propose higher requirement.

On November 20th, 2013, Chinese invention patent CN 102284956 B discloses a kind of automatic drill riveter The normal centering method of device people, it is by 4 the laser displacement sensor detection meters being arranged on end effector Calculate the deviation of normal direction at tool axis and drilling, the adjustment amount in 6 joints of calculating robot on this basis, Thus adjusting the concordance of tool axis and eyelid covering normal direction, this posture adjustment mode is mainly used in aircraft wing parts, hangs down Normal direction posture adjustment during the widget assembling drillings such as tail, but dock joint for big aircraft such as C919 fuselage For drilling, the assembly system of this console model cannot be carried out meeting.

On 03 28th, 2012, Chinese invention patent CN101957175B disclosed a kind of micro-flat based on 3 Facial normal detection method, the method uses plane approximation to replace micro-curved surface, and applies laser displacement sensor skill Art and data acquisition technology, record the method for the normal vector of tested point on curved surface, this detection by certain algorithm Method needs to utilize sensor to gather 30 surveys on the sphere drafted during being disadvantageous in that normal direction detection Measure point thus laser displacement sensor attitude parameter demarcated, calculating process thus can be made to become complicated, Automatization cannot be applicable to and bore the end effector normal direction centering of riveting system.

In 7th phases " modern Manufacturing Engineering " in 2010, disclosing author is Xie Youjin, Wang Zhongqi, Kang Yong Just, should approach and solve deformation surface normal vector algorithm research by brilliant sphere, its sphere described approaches and solves Deformation surface normal vector algorithm can solve the problem of Real-time solution surface points method misorientation amount, but this measuring method As traditional detection method, also existing detection equipment requirements high, data acquisition amount is big, and data process multiple The deficiency of length miscellaneous, time-consuming.

Summary of the invention

The technical problem to be solved is to overcome the defect of prior art, it is provided that a kind of use device knot Structure is simple, step is easy, centering precision high and can be suitably used for the method based on parallel institution of big parts assembling drilling To aligning method.

In order to solve above-mentioned technical problem, the normal centering method based on parallel institution that the present invention provides, should The device that method is used includes parallel institution, cross slid platform, four laser displacement sensors and end effector； Described parallel institution includes fixed platform and the moving platform being connected by connecting rod；Described end effector is arranged on also On online structure moving platform, described parallel institution fixed platform is arranged on cross slid platform, and described four laser displacements pass Sensor is arranged on end effector；The method comprises the steps:

1), coordinate system is set up: navigated to by end effector in predetermined position and attitude, fixed at parallel institution Set up parallel institution coordinate system on platform, the tool axis direction of end effector is set up tool coordinates system；

2), expectation Attitude Calculation: detected by end effector four laser displacement sensors and make on curved surface The expectation normal direction attitude of hole location；

3), parallel institution adjustment amount calculates: by end effector current normal direction attitude and expectation normal direction attitude Deviation obtain respectively against solution the length of parallel institution telescopic rod, the parallel institution translational movement on cross slid platform and The amount of feeding of cutter；

4), according to step 3) try to achieve the length of parallel institution telescopic rod, parallel institution on cross slid platform The amount of feeding of translational movement and cutter completes end effector normal direction centering.

In the present invention, described step 3) in the calculation procedure of parallel institution adjustment amount as follows:

31), use parallel institution to fix by fixed platform, tool axis is adjusted in the way of moving platform adjustment with The expectation normal direction attitude of drilling position is identical；Calculate the coordinate of the most virtual point of a knife point, and obtain parallel institution The length of telescopic rod；

32), complete step 31) after by end effector along cross slid platform X to the translation of, Y-direction, simultaneously Virtual point of a knife point, along its axis direction Z-direction feeding, is moved to drilling position, then step 31 by cutter) in Deviation between coordinate and the coordinate of drilling position of the virtual point of a knife point obtained is exactly the flat of end effector Shifting amount and the amount of feeding of cutter.

In the present invention, described connecting rod includes 2 expansion links and 1 fixing bar, and described telescopic rod is with fixing Bar is all connected with moving platform by Hooke's hinge, and described telescopic rod is connected with fixed platform by spherical pair, fixing bar It is connected with fixed platform.

The beneficial effects of the present invention is: the device that (1), the present invention use inherits parallel institution rigidity weight Ratio is big, bearing capacity is strong, the advantage of fast response time, and its inverse arithmetic is simple, precision is high, it is possible to quickly, Realize end effector normal direction centering exactly；(2), can directly calculate according to the expectation attitude detected The adjustment amount of parallel institution telescopic rod and translational movement, it is simple to bore the gesture stability of riveting system；(3), the present invention Method can be applicable to light-duty brill riveting system normal direction centering of independently creeping, thus meets big airframe docking joint Drilling required precision.

Accompanying drawing explanation

Fig. 1 is the normal direction detection geometric model schematic diagram of the present invention；

Fig. 2 is the normal direction detection plane projection schematic diagram of the present invention；

Fig. 3 is the normal direction posture adjustment geometric model schematic diagram of the present invention；

In Fig. 1, T_PFor virtual point of a knife point, T_P-XYZ is the tool coordinates system before normal direction centering, T_P-X'Y'Z' For the tool coordinates system after normal direction centering；In Fig. 2, B₁P₁、B₂P₂For the telescopic bar of parallel institution, B₃P₃ For fixing bar, O_B-xyz is parallel institution coordinate system, T_P-xyz is the tool coordinates system before normal direction centering, O_PT_P For current tool axis direction, T_P'-x'y'z' is to ensure the tool axis tool coordinates system consistent with normal direction at drilling, O_P'T_P' it is corresponding tool axis direction, T_P-XYZ is to ensure the tool coordinates system that virtual point of a knife point is consistent, O_P″T_PFor desired tool axis direction.

Detailed description of the invention

Below in conjunction with the accompanying drawings the present invention is described in further detail.

The device that present invention normal centering method based on parallel institution is used includes that parallel institution, cross are sliding Platform, four laser displacement sensors and end effector, whole device is controlled to adjust by boring riveting system controller. Above-mentioned parallel institution has two rotational freedoms, including fixed platform and moving platform, between fixed platform and moving platform Be connected by 2 telescopic rods and 1 fixing bar, wherein telescopic rod and fixing bar all by Hooke's hinge with move Platform connects, and telescopic rod is connected with fixed platform by spherical pair, and fixing bar is fixing with fixed platform to be connected, its Chain constitutes SPU structure.Four laser displacement sensors are arranged on end effector, and end effector is arranged on , parallel institution fixed platform is arranged on cross slid platform on parallel institution moving platform also, can realize X and move to, Y-direction Dynamic, cutter spindle feeding can realize Z-direction and move, and therefore, end effector can realize the normal direction of 5DOF and adjust Appearance.

The present invention detects drilling position first with four laser displacement sensors being installed on end effector Put the expectation normal direction attitude at place, then according to the expectation method of end effector current normal direction attitude Yu drilling position Calculate the adjustment amount of parallel institution to the deviation of attitude, thus realize the purpose of normal direction centering.As it is shown on figure 3, For point of a knife point invariant position virtual after ensureing posture adjustment, it is as follows that normal direction posture adjustment realizes process: (1), according to inspection The expectation normal direction attitude of the drilling position measured, the side that mechanism is fixed with fixed platform in parallel, moving platform adjusts Tool axis is adjusted to identical with drilling position law vector by formula, and i.e. tool axis is by O_PT_PAxis transforms to O_P'T_P' process；(2), complete (1) after, by end effector along cross slid platform X to, Y-direction translation (its Direction and parallel institution coordinate system X are identical to, Y-direction direction), cutter enters along its axis direction Z-direction simultaneously Giving, make virtual point of a knife point move to drilling position, i.e. cutter is by O_P'T_P' transform to O_P″T_PProcess；? Ensure virtual point of a knife point T eventually_PPosition does not changes.

The present invention to be embodied as step as follows:

Step 1, set up coordinate system: as it is shown on figure 3, end effector to be navigated to predetermined position and attitude On, utilize laser tracker to set up coordinate system O of parallel institution_B-xyz, its coordinate system center of circle is that parallel institution is fixed Platform center, x-axis is along O_BB₁Direction, y-axis and B₁B₂Parallel, z-axis is perpendicular to fixed platform straight up； In like manner, tool coordinate system T is set up_P-XYZ, its coordinate system center of circle is virtual point of a knife point set in advance, x, y Direction of principal axis and parallel institution coordinate system x before posture adjustment, y-axis direction are identical, and z-axis is along tool axis direction.Two Conversion parameter between coordinate system can obtain from laser tracker.

Step 2, normal direction detect, and draw the expectation normal direction attitude of drilling position on curved surface: as it is shown in figure 1, Four displacement transducer crosss are uniform to be arranged on end effector, and decile layout is centered by tool axis On the face of cylinder of axle, and all becoming α angle to install with tool axis, α angle is 45 degree, so that getting to illiteracy Four laser beams in epidermis face can enough be drawn close again under Uncrossed premise, the installation of laser displacement sensor Point is respectively S₁、S₂、S₃、S₄, requiring during installation that four mount points are coplanar, installation dimension should meetAndWithBeing respectively tool coordinates system X-axis and Y-axis positive direction, four bundle laser exist Subpoint on skin-surface is respectively Q₁、Q₂、Q₃、Q₄,WithIt is respectivelyIn plane YT_PZ and plane XT_PProjection in Z.Order $\stackrel{\‾}{S_1{Q}_1}=h_1,\stackrel{\‾}{S_2{Q}_2}=h_2,\stackrel{\‾}{S_3{Q}_3}=h_3,\stackrel{\‾}{S_4{Q}_4}=h_4,$ θ₁For Z axis arrivesAngle, θ₂Arrive for Z axisAngle, t₁ForArriveAngle.Obtained by geometrical relationship Arrive:

t₁=arctan (cos θ₂×tanθ₁)

As in figure 2 it is shown, θ₁At tool coordinates system XT_PProjection relation in Z plane, according to above geometrical relationship,

Can try to achieve:

${\mathrm{\θ}}_1=\arctan \frac{(h_1-h_2)\×\cos \mathrm{\α}}{l-(h_1+h_2)\×\sin \mathrm{\α}}$

In like manner can obtain

${\mathrm{\θ}}_2=\arctan \frac{(h_3-h_4)\×\cos \mathrm{\α}}{l-(h_3+h_4)\×\sin \mathrm{\α}}$

T_P-XYZ can be by T_P-X'Y'Z' is first around X-axis anglec of rotation θ of self₂, further around the Y being newly formed coordinate system Axle anglec of rotation t₁Obtaining, its rotational transformation matrix is represented by:

R=Euler (0, t₁,θ₂)=Rot (Z, 0) Rot (Y, t₁)·Rot(X,θ₂)=

$\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]\·\left[\begin{array}{ccc}{\cos t}_1& 0& {\sin t}_1\\ 0& 1& 0\\ {-\sin t}_1& 0& {\cos t}_1\end{array}\right]\·\left[\begin{array}{ccc}1& 0& 0\\ 0& {\cos \mathrm{\θ}}_2& {-\sin \mathrm{\θ}}_2\\ 0& \sin {\mathrm{\θ}}_2& {\cos \mathrm{\θ}}_2\end{array}\right]=\left(\begin{array}{ccc}{n}_x& o_x& a_x\\ n_y& o_y& a_y\\ n_z& o_z& a_z\end{array}\right)$

Therefore, it is desirable to virtual point of a knife point terminal angle can be indicated with above formula, thus realize normal direction detection merit Energy.

Step 3, parallel institution adjustment amount calculate: first, tool axis is by O_PT_PTransform to O_P'T_P'。

As it is shown on figure 3, some B_iIn parallel institution coordinate system O_BCoordinate under-xyz is represented by:

B_i=(Rcos θ_bi Rsinθ_bi 0)^T(i=1,2,3)

Point P_iCoordinate under tool coordinates system is represented by:

P_i=(Rcos θ_pi Rsinθ_pi L)^T(i=1,2,3)

R is the parallel institution Platform center distance to pin joint, θ_biFor vector O_BB_iIt is rotated clockwise to parallel connection The angle of Mechanics coordinates x-axis positive direction；θ_piFor vector O_PP_iJust it is rotated clockwise to tool coordinates system X-axis The angle (i=1,2,3) in direction；L is the parallel institution moving platform center distance to virtual point of a knife point.

Thus, P_iIn parallel institution coordinate system O_BCoordinate P under-xyz_i' it is expressed as:

$P_i\text{'}=\left(\begin{array}{c}{p}_{\mathrm{ix}}\text{'}\\ p_{\mathrm{iy}}\text{'}\\ p_{\mathrm{iz}}\text{'}\end{array}\right)={\mathrm{RP}}_i+T=\left(\begin{array}{c}{n}_x{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_x{R\sin \mathrm{\θ}}_{\mathrm{pi}}+{\mathrm{\α}}_{x}L+x_c\\ n_y{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_y{R\sin \mathrm{\θ}}_{\mathrm{pi}}+a_{y}L+y_c\\ n_z{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_z{R\sin \mathrm{\θ}}_{\mathrm{pi}}+a_{z}L+z_c\end{array}\right)$

With in up-conversion process, no matter how moving platform rotates, P₃The position of point remains constant, uses L₃Table Show fixing bar B₃P₃Length, then P₃In parallel institution coordinate system O_BCoordinate under-xyz is represented by:

P₃'=(-Rcos60⁰ -Rsin60⁰ -L₃)^T

Thus the coordinate T=(x of virtual point of a knife point after conversion can be tried to achieve_c y_c z_c)^TExpression formula as follows:

$\left\{\begin{array}{c}{x}_c=-\frac{1}{2}R+\frac{1}{2}{\mathrm{Rn}}_x+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_x-a_{x}L\\ y_c=-\frac{\sqrt{3}}{2}R+\frac{1}{2}{\mathrm{Rn}}_y+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_y-a_{y}L\\ z_c={-L}_3+\frac{1}{2}{\mathrm{Rn}}_z+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_z-a_{z}L\end{array}\right.$

Parallel institution length of telescopic bar L again_iIt is represented by:

L_i=| P_i'-B_i|

Therefore, after posture adjustment, the complete expression formula of parallel institution two length of telescopic bar is:

$\begin{array}{c}{L_i}^2={(n_x{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_x{R\sin \mathrm{\θ}}_{\mathrm{pi}}-\frac{1}{2}R+\frac{1}{2}{\mathrm{Rn}}_x+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_x-{R\cos \mathrm{\θ}}_{\mathrm{bi}})}^2+(n_y{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_y{R\sin \mathrm{\θ}}_{\mathrm{pi}}-\frac{\sqrt{3}}{2}R+\\ {\frac{1}{2}{\mathrm{Rn}}_y+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_y-{R\sin \mathrm{\θ}}_{\mathrm{bi}})}^2+{(n_z{R\cos \mathrm{\θ}}_{\mathrm{pi}}+o_z{R\sin \mathrm{\θ}}_{\mathrm{pi}}-L_3+\frac{1}{2}{\mathrm{Rn}}_z+\frac{\sqrt{3}}{2}{\mathrm{Ro}}_z)}^2(i=\mathrm{1,2})\end{array}$

Secondly, tool axis is by O_P'T_P' transform to O_P″T_P。

Tool axis is by O_P'T_P' to O_P″T_PConversion be one ensure virtual point of a knife point invariant position process, Also it is the rigid translation process of end effector, i.e. by virtual point of a knife point T simultaneously_P' to T_PTranslation motion.Cause This end effector is along parallel institution x-axis, translational movement Δ x, the Δ y in y-axis direction and along tool axis side To amount of feeding Δ z be respectively as follows:

$\left\{\begin{array}{c}\mathrm{\Δx}=x_T-x_c\\ \mathrm{\Δy}=y_T-y_c\\ \mathrm{\Δz}=z_T-z_c\end{array}\right.$

In above formula, x_T、y_T、z_TFor the known coordinate position of drilling position, x_c、y_c、z_cFor step 2 In the T that obtains_P' point coordinate position, i.e. translation matrix T.

Step 4: length L of the parallel institution telescopic rod that step 3 is obtained_i, end effector is along parallel connection The translational movement Δ x of mechanism's x-axis, pass along the translational movement Δ y in parallel institution y-axis direction and the amount of feeding Δ z of cutter It is defeated by brill riveting system controller, completes end effector normal direction centering.

The above is only the preferred embodiment of the present invention, it is noted that for the common skill of the art For art personnel, can also make some improvement under the premise without departing from the principles of the invention, these improve also should It is considered as protection scope of the present invention.

Claims (3)

1. a normal centering method based on parallel institution, it is characterised in that:

The device that the method is used includes parallel institution, cross slid platform, four laser displacement sensors and end Executor；Described parallel institution includes fixed platform and the moving platform being connected by connecting rod；Described end effector Being arranged on the moving platform of parallel institution, the fixed platform of described parallel institution is arranged on cross slid platform, and described four Individual laser displacement sensor is arranged on end effector；

The method comprises the steps:

1), coordinate system is set up: navigated to by end effector in predetermined position and attitude, fixed at parallel institution Set up parallel institution coordinate system on platform, the tool axis direction of end effector is set up tool coordinates system；

2), expectation Attitude Calculation: detected by end effector four laser displacement sensors and make on curved surface The expectation normal direction attitude of hole location；

3), parallel institution adjustment amount calculates: by end effector current normal direction attitude and the phase of drilling position The deviation hoping normal direction attitude obtains the length of parallel institution telescopic rod, parallel institution respectively at cross slid platform against solution On translational movement and the amount of feeding of cutter, and ensure virtual point of a knife point invariant position；

4), according to step 3) try to achieve the length of parallel institution telescopic rod, parallel institution on cross slid platform The amount of feeding of translational movement and cutter completes end effector normal direction centering.

Normal centering method based on parallel institution the most according to claim 1, it is characterised in that: institute State step 3) in detailed process be as follows:

31), use parallel institution to fix by fixed platform, tool axis is adjusted in the way of moving platform adjustment with The expectation normal direction attitude of drilling position is identical；Calculate the coordinate of the most virtual point of a knife point, and obtain parallel institution The length of telescopic rod；

32), complete step 31) after by end effector along cross slid platform X to the translation of, Y-direction, simultaneously Virtual point of a knife point, along its axis direction Z-direction feeding, is moved to drilling position, then step 31 by cutter) in Deviation between coordinate and the coordinate of drilling position of the virtual point of a knife point obtained is exactly the flat of end effector Shifting amount and the amount of feeding of cutter.

Normal centering method based on parallel institution the most according to claim 1 and 2, it is characterised in that: Described connecting rod includes that 2 expansion links and 1 fixing bar, described telescopic rod and fixing bar all pass through Hooke's hinge Being connected with moving platform, described telescopic rod is connected with fixed platform by spherical pair, and fixing bar is connected with fixed platform.