JPS628007A - Automatic measurement method of cross-sectional shape using non-contact sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method of measuring the shape of an object in a non-contact manner using an optical sensor using a laser beam or the like, and particularly relates to a method for measuring the shape of an object in a non-contact manner using an optical sensor using a laser beam or the like.
This invention relates to a method for automatically measuring the contour shape of a defined cross section.

[Background of the invention]

With the remarkable development of opto-electronics, devices that use non-contact optical sensors that use laser light or the like to measure the shape of objects have been developed. For example, sensor technology 19
An example of this is also described in the February 1983 issue of ``Measurement of object shape using a single light point detection sensor''.
1. This type of measuring device is used to measure the shape of an object at a prespecified cross section, such as a horizontal or vertical cross section with an arbitrary inclination for a flat surface, or a cylindrical cross section for a curved surface. Often used. However, if the sensor position and optical axis direction are not set appropriately for this specified cross section,
There was a problem that the measurement point deviated from the intended cross section.

[Purpose of the invention]

An object of the present invention is to provide a method that can automatically measure the contour shape of a specified cross section.

[Summary of the invention]

The present invention takes into consideration that the measurement point tends to deviate from the designated cross section when the optical axis of the sensor intersects the designated cross section at a certain angle, and changes the position of the sensor and the direction of the optical axis. The mechanism is driven and controlled so that a certain relational expression is established, and the optical axis is fully automatically constrained within a specified cross section.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

First, FIG. 2 shows the overall configuration of the measuring device. An optical sensor 3 using a laser beam or the like is arranged opposite to the object 2 placed on the X-direction moving part of the three-dimensional drive mechanism 1, and the sensor 3 is in front of the SW (swing) axis and the BD (bending) axis. It is attached to the two-direction moving section of the three-dimensional drive mechanism 1 via an angle change mechanism 4 having two degrees of freedom in the axis. Further, this two-direction moving section itself is placed on the y-axis direction moving section of the three-dimensional drive mechanism 1. Therefore, the optical sensor 3 three-dimensionally (x+7t
The object 2 can be moved in the ``axial direction'', and the direction of the optical axis indicated by the dashed arrow in the figure can be changed in any direction depending on the shape of the object 2.

FIG. 3 shows a schematic structure of the optical sensor 3. The laser light emitted from the light source 11 passes through the irradiation lens 12, travels on the irradiation optical axis, and is connected to a point r on the surface of the object 2. The reflected light from point P is focused by a condensing lens 13 placed on the receiving optical axis that forms a certain angle [1 -
Detected by The principle of distance measurement is that when the distance t between the object 2 and the optical sensor 3 changes, the light receiving position on the light receiver 14 changes, and this change is electrically detected. In addition, in this sensor, l in the figure on the irradiation optical axis
The distance between min and tmaX can be measured. Note that there is a certain measurable range for the angle between the normal line of the object and the irradiation optical axis.

Next, a method for measuring the shape of an object will be explained with reference to FIGS. 4 and 2. The direction of the irradiation optical axis of the optical sensor 3 (thick broken line arrow in Fig. 4) is determined by the angle change mechanism 4 according to the vertical axis (
It is rotatable circumferentially (SW axis in the figure) and also rotatable circumferentially around the horizontal axis (BD axis in the figure). In this embodiment, these 8W and BD axes are configured to have an intersection Ne on the irradiation optical axis of the optical sensor 3. Also, for the coordinate system 0-xyz of the measuring machine, the SW axis is parallel to the z-axis, and the BD
The axis is set within a cross section perpendicular to the z-axis. Furthermore, S
The rotation angles θ, V, and θb4 of the W axis and the BD axis are each defined as 0 degrees when the irradiation optical axis faces the y direction.

In this embodiment, the coordinates of the irradiation point P on the surface of the object 2 ("P*
'/p, zp) is the coordinate of the measurement coordinate system of the intersection N indicating the sensor position (xN * 3')i + "N),
Further, using the distance measurement value 1t- by the optical sensor, it is expressed by the following equation.

Therefore, while driving and controlling the position of the optical sensor and the direction of the optical axis by the arithmetic and control device (not shown) around the circumference of the object 2,
If the coordinates of the light points P are found at necessary intervals using equation t-(1), the shape of the object can be measured as a set of the coordinates of these light points.

Next, a method for automatically measuring the contour shape of a specified cross section according to the present invention will be explained. The basic principle of the present invention is that when measuring the shape of a specified cross section, first, the relationship between the position of the optical sensor and the direction of the optical axis is calculated so that the optical axis of the optical sensor is within the specified cross section. Then, the three-dimensional drive mechanism and the angle change mechanism are driven and controlled so that this relationship is established, and in this state, the distance is measured by the optical sensor, and the coordinates of the measurement point are determined by equation (1). The point is to calculate. Further, since these calculations, drive control, distance measurement, etc. are all performed by the calculation control device, the shape of the specified cross section can be automatically measured.

First, FIG. 5 shows a method of measuring the shape of a horizontal cross section of an object 2 according to the present invention. In this case, the equation for the horizontal cross section 20 to be found is the translation amount (a* be C) with respect to the measuring machine coordinate system.
Generally, for the coordinate system 0-XYZ that has been translated in parallel by
It can be written as Z=Zc.

Therefore, the position of the optical sensor N (XNI)'NI ZN
) and the directions of the optical axes θsv and θb4, it is necessary to satisfy the following relational expression.

Note that the remaining XN, )'N and θ, are set to appropriate values that satisfy the measurable range of distance and angle of the optical sensor each time the measurement point is updated.

Next, FIGS. 6 and 7 show cross sections 2 perpendicular to the X axis and y axis of the measuring machine coordinate system, respectively, among the vertical cross sections of the object 2.
The method for measuring the shapes of Nos. 1 and 22 is shown below. Each of these #? The surface equations are X”Xc and Y = Yc, respectively
It can be written as (8). Therefore, for the cases shown in FIGS. 6 and 7, it is necessary to set the position of the optical sensor and the direction of the optical axis as shown in the following equations.

In equations (4) and (5), the remaining YN+zN+θbd
and XN, ZN.

The value of 0M is set to an appropriate value that satisfies the measurable range of the optical sensor each time the measurement point is updated.

As seen in these embodiments, according to the present invention, the optical axis is always constrained within the specified cross section, so the measurement points obtained are always within the specified cross section. Furthermore, since these controls are performed automatically, it is possible to automatically measure the shape of a cross section perpendicular to any axis of the measuring machine coordinate system.

Next, consider a more general case, that is, a case where the designated cross section is parallel to one axis of the measuring machine coordinate system and rotated around this axis. FIG. 1 shows an example of this in which the designated cross section 23 is parallel to the X axis of the measuring machine coordinate system, and
The case of a plane rotated by A8 around the X-axis (X/X) is shown. In this case, the equation of the designated cross section 23 can generally be expressed as the following formula, assuming that the coordinate system after rotation is 0-x/y/z/.

z' = Z'c (6
) On the other hand, the following relationship is established between 0-xyz and ox'y'z' using a coordinate change matrix.

From the main ceremony, Z'? When expressed as a value in the measuring machine coordinate system, Z'
=(Z C) C08AX ()' b) 81n
We obtain Ax (8). Therefore, equation (8) and equation (
6), it can be seen that in order to constrain the sensor position N (XN, YN, Zs) within the cross section 23, it is sufficient to satisfy the following relational expression.

(ZN C) CO8AX (yN-b) SinAI
=Z'C-(9) Next, a relational expression that should be satisfied by the direction of the optical axis in this case is determined. Figure 8 shows the position N of the sensor in Figure 1.
It is translated in parallel to the origin 0 of the t-coordinate system ox'y'z'. In order for the vector OP to be within a cross section parallel to the specified cross section 23, Z''' Z C05AX Y ' 1nkx =
O(10) On the other hand, from FIG. 8, the following relational expression holds true.

According to equations α0) and (11), in order to constrain the optical axis within the specified cross section 23, the rotation angles θ, W, and θ of the SW axis and BD axis are
b-, C08AX 5in1944-sinAzcos9. ,
cos θh a = O (12) In other words, Ax is parallel to the X axis of the measuring machine coordinate system and parallel to xMK.
To obtain the shape of the designated cross section rotated by
It is sufficient to set it so that the relational expression is satisfied.

Similarly, in order to find the shape of a specified cross section that is parallel to the y-axis and rotated by A angle around the axis parallel to the y-axis, the position of the optical sensor and the direction of the optical axis are as follows. It can be seen that it can be set using the relational expression.

(zN-C) C03Ay + (XN-a) sinA
y=Z'c-(13)cosAYsinθb4-si
nAysinθ,, cosθba = O (14) Next, Fig. 9 explains the case of finding the shape of a specified cross section that is parallel to the two axes of the measuring machine coordinate system and rotated by Az around an axis parallel to the Z axis. It is something. In this case, the position of the optical sensor N (X N *)'N + ZN) is
A similar calculation shows that the following relational expression should be used.

(YN-b)cosAz (XN-a)sinAz=
Y'c (15) On the other hand, in order to constrain the optical axis within the designated cross section 24, as is clear from the figure, the rotation angle θ1w
must be set using the following formula.

θ−v = “A z□μs) The values of ZN and θbd that do not appear in equations (15) and (16) are calculated based on the distance to the optical sensor and the normal to the measurement surface each time the measurement point is updated. It is sufficient to set it to an appropriate value that satisfies the measurable angle range.

In these embodiments, the optical axis is always constrained within the designated cross section, so the measurement point is always within the designated cross section.

Further, since these controls are automatically performed by the arithmetic and control device, shape measurement can be performed automatically.

Furthermore, since a cross section parallel to any axis of the measuring machine coordinate system and rotated around the axis can be specified as the measurement cross section, the fifth
More general measurements can be performed than the examples described in FIGS. 7 through 7.

The application of the present invention is of course not limited to these embodiments, but for example, the degree of freedom of the angle changing mechanism is not limited to the two axes of this embodiment, but can vary depending on the shape of the object. It is also possible to make it compatible with three axes.

Furthermore, even if the specified cross section is not parallel to any axis of the measuring machine coordinate system, the relational expression for setting the sensor position and the direction of the optical axis is complicated, but the optical axis of the present invention can be constrained to the specified cross section. The method is applicable.

Furthermore, although the embodiments have been described with respect to the case where all the cross sections are flat, it goes without saying that the present invention can also be applied to cases where the cross sections are cylindrical, hyperbolic, or other shapes formed by a collection of straight lines.

In these embodiments, the optical axis of the optical sensor is constrained within a designated cross section by taking as an example a structure in which the optical sensor is attached to a three-dimensional drive mechanism via an angle changing mechanism with at least two degrees of freedom. However, the relationship between the optical axis and the object is relative, and there is a structure in which the object is attached to a three-dimensional drive mechanism via an angle change mechanism with at least two degrees of freedom while the optical axis of the optical sensor is fixed. is also possible. With this structure, in addition to the same effect as the above-mentioned embodiment regarding measurement of cross-sectional shape, it can be expected that the amount of movement of the three-dimensional drive mechanism can be halved.

〔Effect of the invention〕

According to the present invention, the position of the sensor and the direction of the optical axis are set according to a certain relational expression, and the optical axis is always constrained within a specified cross section, so that the contour shape of the desired cross section can be automatically measured. I can do it.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is an overall configuration diagram of a shape measuring device, Fig. 3 is a structural diagram of an optical sensor, Fig. 4 is an explanatory diagram of the principle of shape measurement, and Fig. 5 is an explanatory diagram of an embodiment of the present invention. The figure is an explanatory diagram of one embodiment of the horizontal cross section, FIGS. 6 and 7 are explanatory diagrams of the embodiment of the vertical cross section, respectively, FIG. 8 is an explanatory diagram of the direction of the optical axis, and FIG. 9 is an explanatory diagram of the embodiment of the present invention. It is an explanatory view of an example of. DESCRIPTION OF SYMBOLS 1... Three-dimensional drive mechanism, 2... Object, 3... Optical sensor, 4... Angle change mechanism, 11... Light source, 12...
...To the irradiation lens agent Patent attorney tJs Kawa Tsuneo Kaya l Kata No. δ Kuchi Kaya 2 eyes 4 eyes N (9th, c) Kaya 5 Koka 6 Katagiku eyes

Claims (1)

[Claims] 1. An optical sensor that measures the distance to an object using light, an angle change mechanism with at least two degrees of freedom that changes the direction of the optical axis of the optical sensor, and a position of the optical sensor that changes the direction of the optical axis of the optical sensor. A three-dimensional drive mechanism that changes three-dimensionally, a distance measurement value by the optical sensor, the direction of the optical axis of the optical sensor, and the position of the optical sensor are input and calculated, and the three-dimensional drive mechanism A method for measuring the shape of an object with respect to an arbitrary cross section designated in advance by the measuring device, the method comprising: an arithmetic and control device that controls movement; The relationship between the position of the optical sensor and the direction of the optical axis to be within the cross section is calculated, and the three-dimensional drive mechanism and angle change mechanism are driven and controlled so that this relationship is established, so that the shape of the object with respect to the specified cross section is determined. An automatic method for measuring a cross-sectional shape using a non-contact sensor.