JPS60173407A - Three-dimensional measuring instrument - Google Patents

Abstract

PURPOSE:To measure freely a body for which measuring points are hard to set previously by performing processing on the basis of three-dimensional coordinate values of the body which is measured by moving a measuring element and the difference from designed function data which are stored previously. CONSTITUTION:Pulse signals of a Z, an X, and a Y axis generated corresponding to the vertical movement extent of a moving body 4 having the measuring element 6 fitted atop, the movement extent of an arm 5, and the movement extent of a base on a surface plate are counted by counters in an operation unit 7, and the counted values are converted by decoders into coordinate values (x), (y), and (z) to obtain coordinate values of each measuring point on a car body. Designed curve data of respective data of the car body 1 which are stored in a function data storage device are collated with the measurement data obtained by the measuring element 6 and their errors are displayed on a display device 8. Thus, the outward shape of the car body is measured freely at optional measurement pitch and the need to generate a reference point at every time is eliminated, so that inspection results are fed back to a car body assembling jig, etc., speedily and properly.

Description

DETAILED DESCRIPTION OF THE INVENTION Skin - Part - ■ This invention relates to a three-dimensional measuring device for measuring the shape and assembly dimensions of, for example, a vehicle body.

Follow me, rice! i. In the inspection stage of the vehicle manufacturing process, a three-dimensional measuring device as shown in FIG. 1 is used, for example.

To explain the outline of this device, after a predetermined assembly of a vehicle body 1 as an object to be measured is set on a surface plate 2, a base 3. A measurement mechanism with three axial degrees of freedom consisting of a moving body 4 moving a column 4a and an arm 5 moves a measuring element 6 attached to the tip of the arm 5 to each preset measurement point on the vehicle body 1, and Base for each measurement point 3. Each movement amount of the moving body 4 and arm 5 is detected.

Then, each of these movement amounts is input as a measurement value to the operation unit 7 that has a built-in data processing device, and the data processing device compares and calculates the input reference value with the reference value of the preset measurement point. The dimensional error between the two is calculated, and the resulting dimensional error is displayed numerically on the display 8 together with a code indicating the aIIJ fixed point.

However, with such conventional three-dimensional measuring devices, it is possible to determine whether the measurement point for which the reference value is prepared is the body assembly or whether the iE is always being performed, and the error value can be used to determine whether the vehicle body is being assembled or not. Since the appropriate part and number of measurements are predicted and fixed in order to provide feedback to the tool, the following problems arise.

In other words, with such a setting method, it is not only difficult to set measurement points that take into account variations in the vehicle body, but also
In order to add measurement points, that is, to respond to requests for measurement data at narrower pitches, it is necessary to create a new reference value for each request and record it in the data processing device, which is extremely time-consuming. However, there was a problem in that productivity was lowered due to a delay in feedback to the assembly jig due to an increase in the number of man-hours required for preparation of reference values.

”--Target This invention was made by paying attention to these conventional problems, and it is possible to freely measure at any measurement pitch even for objects to be measured for which it is difficult to set measurement points in advance. I can do it,
Furthermore, the purpose is to eliminate the need to create and register standard values one by one.

To achieve this goal, the three-dimensional measuring apparatus according to the present invention, as shown in FIG. 2, includes a function data storage means 100 that stores function data representing the shape of each part of the object to be measured.

Based on the data specification step 101 for specifying the function data stored in the function data storage means 100, the function data specified by the data specification means 101, and the measured value at the measurement point to which the probe was moved, the corresponding measurement point is Error calculation means 103 that calculates the error between the reference value calculated by the reference value calculation means 102 and the measured value at the measurement point corresponding to the reference value; Display means 104 for displaying the error calculated by means 103 is provided.

Embodiment Examples Examples of the present invention will be described below with reference to FIG. 3 and subsequent figures.

FIG. 3 is a perspective view showing an outline of the mechanical part of the three-dimensional measuring device according to the present invention, and parts corresponding to those in FIG. 1 are given the same reference numerals.

In the figure, a base 3 is mounted on a surface plate 2 on which a vehicle body 1 is placed.
The column 4a is mounted on the base 6 so as to be movable in the Y-axis direction of a fixed coordinate system (orthogonal coordinate system).
! It is erected in the X-axis direction of the I-fixed coordinate system.

A moving body 4 is attached to this column 48 so as to be able to move downward, and a 61q constantor 6 is attached to the tip of this moving body 4.
The arm 5 is attached so that it can be moved in the X-axis direction of the measurement coordinate system.

The movement of the base B is monitored by a Y-axis pulse generator 11 (Fig. 4) consisting of a Y-axis circumferential photo pickup S attached to the base B and a Y-axis circumferential digital scale 10 attached to the surface plate 2. , the movement of the moving body 4 is carried out by a Z-axis photo pickup 12 attached to the moving body 4.
and a digital scale 13 for zIllll attached to the column 4a, etc. 7) Monitoring is performed by a pulse generator 14 for Z 1llll (FIG. 4).

Further, the movement of the arm 5 is controlled by a pulse generator 17 for XIII (FIG. 4) consisting of a first X-axis pickup 15 attached to the moving body 4 and an X-axis circumferential digital scale 16 attached to the arm 5. It is supposed to be monitored.

Therefore, each pulse signal from these X-, Y-, and Z-axis side pulse generators 17, 11, and 14 is used as a base; ) with the origin of the measurement coordinate system as the reference arm 5° base 3. By counting up or down according to the moving direction of the moving body 4, it becomes possible to measure the amount of movement of each axial muscle of the tracing stylus 6. is moved to any measurement point on the vehicle body 1, for example, each measurement point 1a to 1f at the edge part from the roof to the pillar.The dimensions of those measurement points (triaxial coordinate values in the measurement coordinate system )
6 In addition, there is a display 8 that displays measured values and dimensional errors, etc., which will be described later.
is attached to the moving body 4.

Next, FIG. 4 is a block diagram showing the configuration of the operating unit 7. As shown in FIG.

In the figure, the operation unit 7 includes the three-axis coordinate value detection section 1
8, a keyboard 19, a start command button 20, a microcomputer 21 for data processing, a function data storage device 22, and the like.

The three-axis coordinate value detection unit 18 includes x, y, and z-axis axial force counter circuits 180 to 182, decoders 183 to 185, and a gate circuit 186, and operates in a first-order manner.

That is, counter circuits 180 to 182 for x, y, and z axes
are reset by turning on the reset key on keyboard 1S when setting the origin, □ From then on x, y, z
Arm from shaft pulse generator 17, 11° 14 5. Pulse signal P accompanying movement of base 6 and moving body 4
Count up or down x, Py, and Pz depending on the direction of movement.

Count value Nx according to the amount of movement of each axial muscle of the tracing stylus 6.

Output N'I + Nz.

Then, decoders 183 to 185 1. x, y.

Count value Nx' of Z-axis circumference counter circuits 180 to 182
, Ny, Nz, respectively, and calculate these count values Nx, N
Coordinate values (measured values) of y and Nz in the measurement coordinate system where the measuring tip 6 is located [11[gl.

[2], and these coordinate values indicate the dimensions of the measurement point.

Then, the coordinate values [
OC], [y], and [zl are input to the display 8 and displayed, and are also output to the gate circuit 186 and sent to the microcomputer 21 when the gate circuit 186 is opened by turning on the start command button 20. is input.

The keyboard on the 1st includes a reset key for resetting the x, y, and z axis counter circuits 180 to 182 described above, and a function data storage device described later! Character keys and a numeric keypad are used to specify the curve data representing the shape of each part of the vehicle body 1 (Fig. 3) as the object to be measured, which is stored in 22, and to specify the cutting plane axis, which will also be described later. It is equipped with an end key (which may be substituted by a combination of character keys) that is turned on at the end of the measurement.

That is, this keyboard also functions as data designation means.

The start command button 20 opens the gate circuit 186 of the three-axis coordinate value detection section 18 and outputs the coordinate value [X] when the goo 1 circuit 186 is opened.

This is a button switch that is turned on to temporarily store [gco, [2] in the data memory in the microcomputer 21 and prompt the execution of data processing.

The data processing microcomputer 21 includes a central processing unit (CPU) 210. Block Memo + J (ROM
) 211, data') memo+) (RAM) 212, input interface 216. and output interface 21
4, etc., and the CPU 210 executes various block diagrams described later stored in advance in the RoM 211, including coordinate values from the triaxial coordinate value detection unit 18, key operation data from the keyboard throughout the day, and an ON command for the start command button 2o. processing and displaying the processing results on the display 8,
It appears in peripheral equipment such as a data typewriter, CRT, or X-■ plotter (not shown).

The function data storage device 22 is a microcomputer 21
is connected to the pass line of the microcomputer 2.
The address defined on the CPU 21 side is assigned, and the CPU 21
0 can be accessed directly.

The function data storage device 22 stores the designed line shapes (edge shapes such as character lines and parting lines) of each part of the vehicle body 1 as the object to be measured.
Curve (function) data representing each is stored.

That is, for example, as shown in Fig. 3, the curve ■ representing the shape of the edge from the roof to the pillar of the vehicle body 1, the curve II representing the shape of the edge of the cowl top, etc. It is remembered in form.

However, this space curve (parameter cubic equation) R(t) is 6
It is a curve defined in a constant coordinate system, and has a coefficient A.

n, C, and D are values specific to each curve.

Note that this curve includes a straight line, and the storage specification may be such that only the coefficients of A, B, C, and D are stored.

Hereinafter, while also referring to the flow diagrams in FIGS. 5 and 6,
The usage and operation of the three-dimensional measuring device according to the present invention will be explained in order.

When the power of the operating unit 1-7 is turned on, the CPU 210 of the microcomputer 21 performs a predetermined initialization process (not shown), and then proceeds to step 5TEP shown in FIG. 5 to wait for data input.

Next, the measurer moves the measuring stylus 6 shown in FIG. The numerical values Nx, Ny, and Nz of the X, Y, and Z-axis counter circuits 180 to 182 in the value detection unit 18 are set to "0".
Reset to .

Then, the user operates the keyboard of the operating unit 7 to specify the curve and cutting plane axis corresponding to the part of the vehicle body 1 to be measured.

For example, if the part to be measured is an edge from the roof to the pillar, enter the curve base or number representing curve I, and if the measurement starts from the roof side, set the cutting plane axis to [X] and press keyboard 1 to 19 respectively. Specify and input in order.

J3, the cutting plane axis shall be specified by, for example, which axis of the three orthogonal axes the direction of the line of the part to be measured is oriented toward, such as [X] for the roof part and [X] for the pillar part.
Z].

Then, on the first day of this keyboard, for example, when the above-mentioned curve ■ and cutting plane axis [X] are specified, and these data are input into the input interface 21 B, c
p u 2 I O transfers the curve specification data of the input data to the curve specification data storage area in the RAM 212 at 5TEP 3 of the 5H, and transfers the cutting plane axis specification data to the axis specification data in the RAM 212 at 5TEP 5 of Fig. 5. Each time is stored in the storage area.

Note that the input order of both data is arbitrary, and unless the start command button 20 is turned on, ST'EP I in FIG.
Since a loop of ~6,1 is formed, both data can be updated at any time by distribution based on the data check of 5TEP2.4.

Next, after the measuring person 5 moves the measuring stylus 6 shown in FIG.
When 0 is turned on, the on command is input to the input interface 213 of the microcomputer 21, and
The coordinate value (41 Fixed value) [Father], [! ! ], [Z passes through the gate circuit 186 and is also input to the input interface 213, so the CPU 210 operates as shown in FIG.
From 5TEP 7, coordinate value [z] +
[! I] + [Z is temporarily stored in the measured value storage area of the RAM 212.

Note that the coordinate values stored in the RAM 212 are numerically displayed on the display 8.

When the storage process of 5TEP 7 is completed, the CPU 210 proceeds to 5TEP 8, and in 5TEP 3, the RA and M212 are stored.
A curve data search is performed in the function data storage device 22 based on the curve designation data stored in the function data storage device 22.

That is, if it is a specified curve I, the function data storage device 22 is searched and R(t)=At which is data representing the curve I is searched.
' Read +Bt2+Ci+D.

Then, the CPU 210 temporarily stores the read data at 5TEP 8 in the curve data storage area in the RAM 212 at 5TEP 9.

Next, the CPU 210 proceeds to 5TIEPIO and executes a cutting plane creation program as shown in FIG. 6, for example.

In other words, the first 5TEP 100 is 5TEP 5 in Figure 5.
and the cutting plane axis designation data and coordinate values [Oc] stored in the RAM 212 at 5TEP 7,, [! f], [
z], and in the next 5TEPIO1, check the read cutting plane axis designation data, and if that data is [X], then 5TEP102, [5TEP1
03 and [2], the processing proceeds to 5TEP 104 and performs the following processing.

For example, the vector equation for the plane π shown in FIG.

7L), where P is an arbitrary point on the plane π, and d is the distance from the plane π to the coordinate origin, it can be expressed as NP=d.

Therefore, for example, the vector formula for a plane that is perpendicular to the X-axis and whose distance to the origin is the X-axis coordinate value is that the normal vector is Nex
= (1,O,,0), so it can be expressed as Nex j P=+.

Similarly, the vector formula for a plane perpendicular to the Y-axis and the distance to the origin or the Y-axis single target value y is that the normal vector is Ney = (0,
1, O), so Ney−P=,! / It can be expressed as .

In addition, the vector formula for a plane perpendicular to the Z-axis and the distance to the origin having a two-axis coordinate value of 2 is that the normal square is Nez= (o,
O, I), it can be expressed as Nez-P=z.

Therefore, if the cutting plane axis specification data is [X], CP T
, J 2 l [1 is 5TEP in Figure 6] 02, 5r
The X-axis coordinate value of the coordinate values read out in pp1oo [
By using ri=], form the specification data (], O, O, !: c), and use it to cut a curve perpendicular to the X axis related to the measurement point where the probe 6 is positioned. form a cutting plane. .

Similarly, if the cutting plane axis specification data is [Y] (0, 1,
If the cutting plane axis specification data is [z], then the data with the specification becomes (0, 0, 1, z), respectively.
4, thereby creating a cutting plane for curved cutting perpendicular to the Y-axis or Z-axis related to the measurement point where the measuring tip 6 is positioned.

When the measuring head 6 is positioned at the first measuring point 1a, the cutting plane axis is specified as [X], so the CP
U210 is 5TEP102 (], 0.O.

X) form the data.

Then, at 5TEPII in FIG. 5, the cPU 210 sends the data indicating the cutting plane created as described above [-('+ ``l''T d) for the membrane type] to the cutting plane data storage area in the R, AM 212. Store temporarily.

Next, the CPU 210 performs the following reference value calculation at 5TEPi2 in FIG.

That is, the CPU 210 performs R, A M at 5 TEP 9.
The curve data R(t) stored in 212 and ST'EP
Find the intersection point between the two using the data (29m, n, male) indicating the cutting plane related to the measurement point based on the I11100 measurement value at which the measuring tip 6 is positioned and stored in the RAM 212 in II. The reference value (“or!fO+ 70”) corresponding to the measurement point is set as the reference value (“or!fO+ 70”).

The method of determining the intersection point as this reference value is as follows.

As shown in FIG. 8, if the intersection of the plane π and the curve R([) is P, the intersection P is a point on the plane π, so the plane π
As mentioned above, it can be expressed as N-P=d...(]:).

Also, if the value at point P of curve R(t) is R(1:p), then write P=R(t, ρ)...■, and from equations (1) and (2), N-R (tp)=d holds true.

Now, considering the function F(t)=N -R(t)-d, if we do not subtract t when F(t)=O, then t is tp, and P can be calculated accordingly. I can do it.

The solution to F(t)=0 can be found using Newton's method as shown below.

F(t) N-R(t) -d Therefore, one curve R(t) and the cutting plane ('+"+7+,
d) If [11 fixed point 1a, (1, 0, 0, C)] is known, then PteR(tp) = (sword 0 + !I
O+2o) can be calculated.

However, the standard value ("o +, !10 r zo
) is consistent with the uniaxial value used when creating the cutting plane. For example, the reference value for measurement point 1a is (
Sword + gO + ”0).

In addition, when finding an approximate solution using Newton's method, t
The number of operations of i+l: t i, ten Δt is the number of times until the error of the approximate solution with respect to the true solution falls within the measurement accuracy range.

Then, crt121Q is 5TEPI3 in Figure 5.
After temporarily storing the reference value set in TEP12 in the reference value storage area in RAM212, the process proceeds to 5TEPI4, and the error between the coordinate value indicating the measured value at the measurement point and the reference value corresponding to that measurement point is calculated. calculate.

In other words, the CPU 21Q uses the STI:l)7 and the RAM 21
The coordinate values stored in 2 are [father], [gF, and [21].

5TEP], the reference value [Oc
o co.

[,! 10] and [7o] respectively, Δritsu=
r,−ICo,Δ,! /=! /-! l'Q, Δ7:
2 7 Calculate g.

However, as described above, with respect to the specified cutting plane axis, the error is "0". For example, ill! Regarding the l fixed point 1a, Δto=0.

Then, the CPU 210 calculates the dimensional error ΔX
,Δ! /IΔ2 is temporarily stored in the error data storage area in the RAM 212 at 5TEP
Proceed to I6 and calculate the dimensional error Δt, Δy.

ΔZ is numerically displayed on the display 8, and in the next 5TEP17, the end key for one day on the keyboard is turned on, and it is checked to see if it has finished at 1t (l). If the measurement is finished, the process is finished and Otherwise, return to ST[EPI and wait for next data input.

Then, the measurer measures the measurement points 1b+1c+ld in Fig. 6,
By repeating the measurement work as described above, without specifying an appropriate cutting plane axis for each 1f (the specification of the curve does not need to be changed), each /llll+fixed point 1t
, the dimensional error for the setting j1 dimension for each +~1f is 1llll
It is possible to determine the

Then, when the 81!I determination of the iff! 1 constant part corresponding to the 111th!i! After specifying it, you can operate the IF!I fixed work described in 111.

If one-axis values of the coordinate system are used to create a cutting plane, it is not possible to filtrate each of the E-axis XI method errors, but unless the curve representing the shape of the part to be measured is parallel to each coordinate axis, , it is possible to change the cutting plane axis at the same measurement point, so by changing the cutting plane axis at the same measurement point, it is possible to measure the dimensional error of the three axis values, although not simultaneously. I can do it.

Alternatively, the measured dimensional illuminance may be compared with a predetermined permissible illuminance, and an alarm may be issued when a predetermined dimensional error exceeds the permissible illuminance.

Next, a case in which curved surface data representing the surface shape of each part of the object to be measured is used as the function data stored in the function data storage device 22 will be explained in detail.

When this curved surface data is used, the base 1v4Ii value can be expressed in several ways, for example, as described below.

(i) A method in which the coordinate value of the point on the curved surface - where the distance between the point indicated by the coordinate value and the curved surface representing the surface shape of the fixed part d1 is the minimum is used as the reference value. As shown in Figure 9: Curved surface c) (11+ t') that minimizes the distance between curved surface 5 (tt, tr) and point P.
``The tangent vector at any point δS (It i , υL) on the Q1 curved surface (?l, 27) is π.

71 curves at book 9 points (? / i, , υ7), 7
The minute distances in one curve direction are ΔI/i and ΔυL, respectively.

Point (?/i,,2)L)
) is the normal vector of N L ('Bu X&乎).

The intersection of the straight line passing through points P and Q and the curved surface S(?t, υ) is
Since it is a point on a straight line and also a point on a curved surface, the following holds true.

When you accumulate and organize, becomes.

and organize it.

becomes.

Therefore, the above jJl, ti5 (formula and the following f mark,
(Formula 11 1t i, +1 = tt i +Δ 11
i ... (612) i+]−υ2+Δυi −
++...(, 71), it is possible to find the intersection Q using Newton's method on the condition that the coordinate values of the curved surface S(+z, υ) and the point P are known.

If the above-mentioned point P is the point indicated by the measured coordinate value, this intersection Q has the property that it coincides with point P unless the measured coordinate value contains an error, so the coordinate value obtained by measurement [ x], [yl[7] and the function data storage device 22
The intersection point data determined based on the curved surface data S (u, v) retrieved from the curve data group stored in the curve data group can be used as the reference value corresponding to the measurement point.

(11) A method in which the reference value is the coordinate value of the intersection of a curved surface representing the surface shape of the part to be measured and a straight line that is parallel to the direction of the coordinate axis that intersects this curved surface and passes through the point indicated by the measured coordinate value. The straight line P+δt shown in the figure (δ is the direction solid 1
The condition for finding the intersection between the curved surface S (7Z + 2') and the curved surface S (7Z + 2') is as follows, which is almost the same as the above-mentioned equation 0.

Therefore, in this method as well, the reference value can be determined in substantially the same manner as described above.

However, it is necessary to specify the coordinate axis that intersects the curved surface for each measurement point, and if the specified coordinate axis is [X], then the direction vector δ is (
1, O, O), [Y] is (0, 1,, O) and [Z] is (0, 0, 1).

The dimensional error of the measured coordinate values can also be calculated using the reference value determined by the method described in Section 2 (+) or (11).

In addition, -1-, although the above embodiment has been explained by taking the measurement of a vehicle body as an example, it goes without saying that the measurement of any object to be measured can be carried out in the same manner.

As explained above, according to this invention, the predetermined four
19 A reference value corresponding to a fixed point is automatically created based on the function data representing the external shape of each part of the object to be measured and the measured value at that measurement point, and the created reference value corresponds to this reference value. Since the error from the measured value is calculated and displayed, the scale can freely measure the external shape of the object to be measured at any measurement pitch, and there is no need to create and register reference values one by one.

Therefore, when inspecting a car body, for example, even if it is difficult to set the parts to be measured on the car body for the first time, measurements can be made according to the degree of variation1-, which allows for quick and appropriate inspection. It becomes possible to feed back the results to the vehicle body assembly jig, etc.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a conventional example of a three-dimensional measuring device;
3 is a block diagram showing the configuration of the present invention, FIG. 3 is a perspective view schematically showing the mechanical part of the three-dimensional measuring device according to the present invention, and FIG. 4 is a block diagram showing the configuration of the operating unit in FIG. 3. Figures 5 and 6 are flowcharts of processing blocks executed by CI"tJ in Figure 4, respectively. Figures 7 and 8 are explanations of the flowcharts in Figures 5 and 6, respectively. Figures 9 and 10 are diagrams for explaining reference value calculation when curved surface data is used as function data. 1...!J (body body (object to be measured)) 2... Surface plate 3・
Base 4... Moving body 4a, Column 5, Arm E+,? 11! I constant 7...Operation unit 8...
Display unit 11... Y-axis pulse generator 14... Z-axis pulse generator 17... 2 Microcomputer 22...Function data storage device Fig. 1 Fig. 2 Fig. 3 Fig. 6 Fig. 7 ^ Fig. 8

Claims (1)

[Scope of Claims] 1. A three-dimensional measuring device in which a measuring element having three axial degrees of freedom is moved over an object to be measured placed on a surface plate to determine the shape and dimensions of the object. Function data storage means storing function data representing the shape of each part of the object to be measured, data designation means for designating the function data stored in the function data storage means, and function data designated by the data designation means. a reference value calculation means for calculating a reference value corresponding to the measurement point based on the measurement value at the measurement point to which the measuring point has been moved; and a reference value calculated by the reference value calculation means and corresponding to the reference value. A three-dimensional measuring device comprising: an error calculation means for calculating an error between a measured value at a measurement point; and a display means for displaying the error calculated by the error calculation means.