JPH081380B2 - How to measure the object - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a measuring method suitable for automatically measuring an object by a measuring device such as a coordinate measuring machine in an unmanned operation.

(Prior Art) A measuring device such as a three-dimensional measuring machine moves a sensor to a plurality of measurement positions taught in advance while moving the sensor from the measurement position toward the target object so that the sensor moves to the target object. The approach procedure of measuring the position of the object with respect to the measurement position from the signal output by the contact of is repeated, and the shape of the object is measured from the point group representing the position of those objects.

The measuring device as described above normally incorporates the taught measurement position in a sensor movement program that it has in advance, and operates according to the program to automatically measure the object by the movement of the sensor described above. It can be carried out.

(Problems to be Solved by the Invention) By the way, since the above-described measuring device measures the shape of the object as a point cloud, it is necessary to increase the number of points forming the point cloud in order to increase the degree of detail of the measurement result. Therefore, since the measurement time also requires a long time, it would be convenient if the measurement can be performed by unmanned operation at night, etc., because the man-hour will not be required.

However, in the above conventional measuring device, when the sensor is moved toward the object at the taught measurement position, the signal indicating the contact with the object is not output even if the sensor moves to the movement limit position. In this case, for example, when the sensor comes off the object at the taught measurement position,
After stopping the sensor at the movement limit position, the sensor enters a standby state waiting for input of an instruction, which causes a problem that unmanned operation at night or the like cannot be performed.

The present invention provides a measuring method that advantageously solves such a problem.

(Means for Solving the Problem) A method of measuring an object according to the present invention is such that a sensor is moved toward a target from the measurement position while sequentially moving the sensor to a plurality of predetermined measurement positions. When repeatedly performing the approach procedure of measuring the position of the object with respect to the measurement position from the signal output by the contact with the object, the sensor is set at a predetermined position in the process of the approach procedure at one of the measurement positions. If the sensor does not output a signal indicating the contact with the object even after being moved to, the approach procedure is performed for the next measurement position.

(Operation) According to this method, even if the sensor comes off the object in the course of the approach procedure, the approach procedure is performed by moving to the next measurement position, so the measurement device remains in the standby state even when performing unmanned operation. Therefore, the measurement does not end and the detail of the measurement result can be increased without requiring a lot of man-hours.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing functional blocks of a measuring system for a body panel molding die, to which an embodiment of an object measuring method according to the present invention is applied. In FIG. 1, reference numeral 1 is a computer-aided design (CAD). ), A host computer 2 which is also used for computer-aided machining (CAM) and has a relatively large processing capacity and storage capacity, and 2 is a host computer used for controlling the measuring device and processing the measured data. The minicomputers 3 and 3 each having a smaller calculation processing capacity and storage capacity than the computer 1 indicate a coordinate measuring machine as a measuring device, which is used for measuring the shape of the body panel molding die.

The host computer 1 here is a die face
Four CAD parts, a CAD part 4, a free-form surface CAD part 5, a prescribed curved surface CAD part 6 and a mold structure CAD part 7, and a reference data creation part 8,
With the external communication unit 9, a database file 10, a molding surface shape data file 11, a trim, a flange shape data file 12, a structure shape data file 13,
It comprises six storage files of a reference data file 14 and a measurement data file 15, and the minicomputer 2 in this case includes an external communication unit 16 and an error amount calculation unit.
17, a measurement NC data creation unit 18, a device control unit 19, and a measurement data correction unit 20, and two storage files, a reference data file 21 and a measurement data file 22, and each keyboard Also, two input / output terminal devices 23 and 24 having an image display, an XY plotter 25 that draws a diagram based on input signals, and a printer 26 that prints out based on input signals are connected.

The functions of the respective parts of the host computer 1 and the minicomputer 2 will be described in the description when teaching the measurement procedure described later.

The coordinate measuring machine 3 here has a measuring machine main body 27 having a configuration similar to that of a rectangular coordinate type robot and having improved operation accuracy, a sensor movement control device 28, a current position calculation device 29, A normal touch sensor 32, which includes an operation panel 30 and a position display device 31, is selectively attached to the lower end of the wrist of the moving arm of the measuring machine main body 27 and is moved with respect to the measuring object. And a linear sensor that continuously measures the distance to an object after it comes into contact with the object
33, and a manual pulse generator 34, a joystick pendant 35, and those manual pulse generators for moving the sensor position by manually inputting a signal.
34 and a joystick pendant 35 and an interface (I / F) 36 for connecting the sensor movement control device 28.

FIG. 2 is a block diagram showing the measurement control system of the coordinate measuring machine 3 described above. The sensor moving device 28 in this case is equipped with a normal microcomputer, and is provided in the measuring machine main body 27, and the X axis of the arm is provided. , X-axis linear encoder 37 that outputs the current position in the Y-axis and Z-axis directions, Y-axis linear encoder
Signals from the 38 and Z-axis linear encoder 39 and a θ-axis rotary encoder 40 that is connected to a connector for mounting the sensor on the wrist of the arm and outputs the current direction of the sensor are controlled by the arm and the connector. The present position and thus the present position of the sensor are directly detected, and the feedback control using the present position performs feedback control using the present position. The ball screw shaft 41 for driving the X-axis direction, the ball screw shaft 42 for driving the Y-axis direction, Z An X-axis motor 44, a Y-axis motor 45, which are respectively coupled to the axial driving ball screw shaft 43 and the wrist driving shaft,
Operate the Z-axis motor 46 and the θ-axis motor 47 to
Based on the NC program for automatic measurement given from the minicomputer 2, 32 or 33 is moved along a path corresponding to the shape of the object, and when the touch sensor 32 is used, the probe of that sensor is used during the movement. The process of taking in a signal from the sensor 32 indicating that the object has contacted the object and the contact direction, calculating the coordinates of the contact point on the measuring machine coordinate system from the position of the sensor, and outputting to the minicomputer 2. When the linear sensor 33 is repeatedly executed, only the movement is performed.

Incidentally, the sensor movement control device 28, the operation mode switching signal from the operation panel 30, other than the automatic operation mode described above,
A manual operation mode in which the sensor is moved based on the movement command signal from the manual pulse generator 34 or the joystick pendant 35 operated by the operator can also be performed, and the emergency stop signal from the operation panel 30 allows the sensor to operate. It is possible to repeatedly stop the automatic measurement as described above in response to an emergency stop of the movement and the cycle start signal from the operation panel 30.

Then, the touch sensor 32 and the linear sensor 33 are feedback-controlled by the minicomputer 2 to cause the probe to oscillate as shown by arrows α and γ in the drawing and rotate as shown by arrows β and δ in the drawing at arbitrary angles. You can do it and orient the probe in the desired direction.

On the other hand, the current position calculation device 29, which also includes an ordinary microcomputer, has three linear encoders 37-
The signals from 39 and the rotary encoder 40 are input, and the current position of the sensor is detected from these signals by the sensor movement control device 28.
Separately from this, the position is obtained substantially continuously and in an extremely short time, and the position is output to the position display device 31 via the minicomputer 2 and displayed there momentarily.

The current position calculation device 29 also receives a signal from the linear sensor 33, calculates the current position of the probe of the sensor from the signal, and outputs it to the minicomputer 2.

The host computer 1 of such a measuring system has the functions of CAD and CAM as described above, and the measurement in this embodiment is designed as follows using the CAD and CAM functions of the host computer 1. The target is the manufactured mold.

In other words, the mold here is another CAD not shown.
The host computer 1 uses the CAD data that was created during the vehicle body design using the device and shows the shape of the vehicle body panel in the form of mathematical formulas.
And design the molding surface shape such as the punch of the mold by the die face CAD unit 4 based on the data in the database file 10 regarding the moldability such as the spring back and the elongation of the panel from the CAD data of the body panel, The CAD data showing the forming surface shape by a mathematical formula is transferred to the free-form surface CAD section 7 and stored in the forming-surface shape data file 13, and then the free-form surface CAD section 7 extracts the forming surface shape from the above-mentioned data file 13. It is suitable for teaching the moving path of tools and sensors to numerical control (NC) machine tools and the three-dimensional measuring machine 3 here from the above CAD data that expresses
A numerical model that represents the molding surface shape with a point cloud is created, and along with this, the trim and flange line shape data created from the contour shape of the vehicle body panel by the die face CAD section 4 is transferred to the specified curved surface CAD section 6 to perform trim and flange. Trim stored in the line shape data file 12 and then extracted by the specified curved surface CAD unit 6 from the data file 12,
Corresponding to the flange line shape with a relatively simple specified curved surface such as a cylindrical surface or flat surface, the shape of the profile surface such as vertical wall surface or inclined wall surface used for trim processing or flange forming around the punch etc. A numerical model represented by is created, and based on the data in the structure portion shape data file 11 regarding the shape of the structure portion such as the cam surface and the positioning hole, the die structure CAD unit 5 arranges the cam surface and the positioning hole of the mold. To create a numerical model showing the arrangement of these surfaces by point clouds, and create the tool movement path of the NC machine tool from the numerical models created by the free-form surface CAD section 7 and the specified curved surface CAD section 6 above. After the parts such as punches, dies, and pads of the mold are cut and finished by teaching the machine tool, the parts are assembled based on the mold structure designed by the mold structure CAD unit 5.

The above numerical model is, for example, for a molding surface, as shown in FIG. 3, on a predetermined reference plane (usually a plane parallel to the plane including the x and y axes in the mold coordinate system) that covers the molding diagram. The reference line arranged in a grid pattern on the
When projected onto the molding surface in CAD data, the point group of each intersection (grid point) of the reference line on the molding surface represents the three-dimensional shape of the molding surface, and the above-mentioned mold of those grid points It consists of x, y, and z coordinate data in the coordinate system. However, the orientation and inclination of the reference plane can be selected as appropriate according to the orientation and inclination of the surface that should represent the shape.For example, for numerical data related to profile surfaces and mold structures, the reference for the orientation and inclination along the surface that should represent the shape It can be created using a plane.

Then, here, the procedure for measuring the shape of each part of the mold is taught to the coordinate measuring machine as described below.

That is, here, first, the reference data creating unit 8 is caused to create reference data serving as a teaching reference of the measuring means of the molding surface, the profile surface, and the die structure surface such as the cam surface and the positioning hole from the above numerical model.

The reference data here is preferably from the reference line of the numerical model as shown in FIGS. 4 (a) and 4 (b) for the measurement of the molding surface, for example, on the same reference plane used to create the numerical model. Shows the cross-sectional shape when the three-dimensional shape of the numerical model is cut in a plane orthogonal to the above-mentioned reference plane by arranging the cross-section lines in a grid pattern or a striped pattern with coarse intervals by a sequence of points. Shall be represented in.

Here, the cross-section lines are arranged in a striped pattern (the direction can be selected as appropriate) if the overall undulation features of the numerical model can be sufficiently captured in the striped pattern, and in a grid pattern if the striped pattern is not sufficient. And Further, if the cross-section line overlaps with the reference line of the numerical model, the data of the point sequence can be directly obtained from the grid point, so it is preferably arranged so as to overlap with the reference line.
It does not necessarily have to overlap with the reference line, and when they do not overlap, the data of the point sequence is obtained by calculation of linear or curved line interpolation between the grid points. The data of each point constituting the point sequence of the reference data is represented by x, x in the mold coordinate system as shown by a point sequence An (n = 1, 2 ...) When the cross section is viewed from the front in FIG.
In addition to the y- and z-axis coordinate values, the normal vector V / _n of the surface represented by the numerical model at that point is included in order to control the sensor orientation and approach direction described later.

Further, the reference data here is the above-mentioned lattice-shaped or striped cross-section by arbitrarily designating the start point S and the end point E of the section line on the reference plane as shown in FIG. For one or more cross-section lines that are arranged to incline at an arbitrary angle with respect to the line, the cross-sectional shape of the numerical model along with the grid-like or striped cross-section line described above is detailed using a point sequence. Shall be represented in. Such an inclined cross-section line is suitable for measuring a characteristic undulation (character portion) formed on a part of the vehicle body panel or a joggle processing portion.

The reference data is created by using the image display of one terminal device 24 of the minicomputer 2 on the host computer 1
Displaying the shape of each part of the mold based on the numerical data input via the external communication units 9 and 16 from the computer, and observing the shape and transmitting the creation instruction input using the keyboard from the minicomputer 2 to the host computer 1. Select the grid line or stripe pattern for the layout of the cross-section lines, the direction of the cross-section line in the grid pattern or the stripe pattern (usually parallel to the x-axis or the y-axis, or both). ,), The designation of cross-section lines that are inclined with respect to those cross-section lines, and the designation of the spacing pitch of the grid or striped cross-section lines and the spacing pitch between the points forming the point sequence. The pitch between the lines and the points here may be equal intervals, but may be partially narrowed or widened as required.

However, since the numerical data of the forming surface and the profile surface also give the movement path of the tool of the machine tool, an edge portion is added around the original forming surface and the profile surface. When creating the data, refer to the trim, flange line shape data, etc., and, for example, as shown in FIG. 7 as a dot sequence when the cross section along the inclined cross section line in FIG. 6 is viewed from the front direction, It is created by removing the part where the measurement object is actually gone.

The reference data creation unit 8 of the host computer 1
The reference data created by is stored once in the reference data file 14 here, and then transferred from the host computer 1 to the mini computer 2 via the external communication units 9 and 16, and the reference data file 21 of the mini computer 2 is transferred. Memorize to. In this way, all the reference data are stored in the minicomputer 2.
By having it inside, it is possible to make a comparison between a measurement command and measurement data, which will be described later, and the reference data in an extremely short time.

Thereafter, here, the cross-section line of the reference data is displayed on the image display of the terminal device 24 of the minicomputer 2 as shown in FIG. 8, and the cross-section line displayed by the input means such as the keyboard and the mouse. Of these, the range in which actual measurement is required is specified as indicated by the broken line in the figure, and the basic approach amount A _P0 and additional approach amount A _P1 which will be described later are specified. If the cross-section line of the reference data is a grid, the striped measurement and its direction can be specified.

After inputting the designation of the measurement range, the type of section line, the approach amount, etc. as described above, the measurement NC data creation unit 18 of the minicomputer 2 fetches from the reference data file 21 according to the designation contents. The automatic measurement NC data for specifically teaching the movement path of the sensor and the measurement processing contents is created based on the reference data. Note that the specified content may be printed on the printer 26 for confirmation prior to its creation.

FIG. 9 exemplifies a specific movement path of a sensor for measuring a molding surface of a mold, in which 50 is an actual molding surface.
Reference numeral 32 indicates a touch sensor.

That is, here, on the clear plane P, which is a horizontal plane set at an arbitrary height so that the die and the sensor do not interfere with each other, the sensor 32 and thus the probe from the first measurement point A ₁ directed from the clear plane P Approach point B ₁ as a measurement position, which is a distance that is the _{sum of the} basic approach amount A _P0 and the additional approach amount A _{P1 in the} direction of the normal vector
To the position above the approach point B ₁ at a high cutting feed rate as shown by the solid line in the figure. Let

Then, here, the probe of the sensor 32 is set to the measurement point A ₁
If the sensor 32 outputs a signal indicating that the probe has contacted the molding surface 50 along the normal line at a normal cutting speed (low speed) so as to pass through it, the contact is made. Perform the approach procedure of obtaining the center position of the probe from the position and direction of the sensor and the contact direction from the output signal of the sensor, and obtaining the actual position of the molding surface 50 corresponding to the measurement point A ₁ from these. .

Then, after the contact of the probe, in parallel with the calculation for obtaining the position of the molding surface 50, the sensor 32 is moved in the opposite direction to the above at a high cutting feed rate, and the probe moves from the measurement point A ₁ to the basic approach amount A _P0 . After returning to the distance, then the probe,
Move from the next measurement point A ₂ to the approach point B _{1 in the} normal vector direction, which is a basic approach amount A _P0 away,
After that, the position of the molding surface 50 corresponding to the measurement points A ₂ , A ₃ , and A ₄ is measured by repeating the same approach procedure as that at the measurement point A ₁ .

Next, here, since the measurement points A ₄ and A ₅ have different cross-sectional lines, the sensor 32 is once raised above the clear plane P,
After that, the measurement points A ₅ and A ₆ are also measured in the same manner as described above.

Here, there is a hole on the actual molding surface or the horizontal contour of the molding surface is small, so the moving direction of the sensor is
When the molding surface is out of the area where it actually exists and the probe does not contact the molding surface 50 even after passing the measurement point in the course of the approach procedure, as shown in FIG. If a contact is not made with the predetermined distance T, the fact is displayed and recorded, and the measurement of the next measurement point is started.

When the touch sensor 32 is used, automatic measurement NC data for instructing the movement path and measurement processing contents is created, and the NC data is transmitted to the sensor movement control device 28 of the coordinate measuring machine 3 via the device control unit 19. Input or teach.

On the other hand, when performing measurement using the linear sensor 33, while maintaining the distance between the surface of the measurement data on the reference data and the probe of the sensor within the measurable range of the linear sensor 33, NC data for automatic measurement is created so as to be continuously moved along, and the coordinate measuring machine 3 is instructed.

The above example is for measuring the molding surface, but here, for the profile surface and the surface related to the mold structure, NC data for automatic measurement is created from the reference data in the same way, and it is taught to the coordinate measuring machine. To do. Therefore, according to this measuring system, not only the shape accuracy of the mold but also the assembly accuracy can be evaluated.

Then, after teaching the automatic measurement NC data, input a measurement start command from another input / output terminal device 23 installed so that other reference data and NC data can be created in parallel with the measurement. The coordinate measuring machine 3 is caused to perform mold measurement based on the inputted automatic measurement NC data.

And here, the sensor moving device 28 of the coordinate measuring machine 3
The device control section 19 determines the actual position of the measurement surface corresponding to the measurement point, which is output one after another by the minicomputer 2
Input into the measurement data, and correct the deformation amount due to the assembly error of the coordinate measuring machine main body 27 and the change of the ambient temperature to the measured position data, and the coordinate conversion from the measuring machine coordinate system to the mold coordinate system is measured data. Performed by the correction unit 20, the measurement data of each point obtained by this is sequentially stored in the measurement data file 22, and is input to the error amount calculation unit 17 together with the reference data of the measurement point corresponding to the measurement data. Then, after calculating the position error amount (deviation) of the measurement data with respect to the measurement point on the reference data in the normal direction of the reference data and converting the position error amount into the hue difference, it is shown in FIG. As described above, the image display of the input / output terminal device 23 is sequentially displayed at the position corresponding to the measurement point as a point of the hue corresponding to the position error amount, and the error amount is also displayed on the image display. Display the numerical value .

After the measurement operation and the display of the error amount during measurement are finished, here, as shown in FIG. 12 (a), the same as the figure showing the normal direction position error amount along the sectional line of the reference data, As shown in the figure (b), the contour line E of the cross-sectional shape based on the reference data along the cross-section line (indicated by the solid line in the figure) and the contour line F of the cross-sectional shape based on the measurement data (indicated by the dashed line in the figure). X and
-Y plot on the plotter 25. Here, the contour line F of the cross-sectional shape based on the measurement data is assumed to emphasize the error tendency. Specifically, as shown in FIG. 13, at each measurement point of the contour line E of the cross-sectional shape based on the reference data. , The above-mentioned vector is not the contour line G of the actual cross-sectional shape obtained by converting the actual measurement data, which is the point at the tip of the vector g · ₁ obtained by multiplying the unit vector ₁ in the normal direction It is assumed that the point at the tip of the vector ₂ ( ₂ = k · g · ₁ ) obtained by multiplying g · ₁ by the highlighting coefficient k (which can be arbitrarily specified) is made into a point sequence.

Even when the measurement is performed using the linear sensor 33, the measurement result may be displayed in the same manner as when the touch sensor is used.

In addition to the display of the measurement result, here, the measurement data is further transferred from the minicomputer 2 to the host computer 1 and temporarily stored in the measurement data file 15, and the host computer 1 displays the actual mold based on the measurement data. Based on the shape, learning for correcting the mold design data in the database file 10 used in the die face CAD unit 4 is performed.

As described above, according to the measurement system here,
Since the cross-sectional shape of the mold can be measured in detail and the measurement result can be displayed when the mold is measured, the characteristic uneven shape of the mold can be sensuously appropriately evaluated, and here, the touch sensor 32 is used. During measurement, even if the sensor comes off the mold during the approach procedure, it moves to the next measurement position and the approach procedure is performed, so the measurement system remains in the standby state even when performing unattended operation. There is no case where the processing is not completed, and therefore the detail of the measurement result can be increased without requiring a lot of man-hours.

Although the present invention has been described above based on the illustrated example, the present invention is not limited to the above-described example, and can be applied to measurement of other objects such as a vehicle body panel.

Further, the measurement position may not be automatically determined from the design shape of the object as in the above example, but may be determined one by one by moving the touch sensor manually in advance. Of course, in this case, the following approach procedure may be performed when the sensor does not show contact with the object even if the sensor has moved a certain distance or more from the measurement position.

(Effect of the invention) Thus, according to the measuring method of the present invention, even if the sensor is removed from the object in the course of the approach procedure, the approach procedure is performed by moving to the next measurement position, so that the measuring apparatus is operated even if unmanned operation is performed. Does not remain in the standby state and the measurement does not end, so that the detail of the measurement result can be increased without requiring a lot of man-hours.

[Brief description of drawings]

FIG. 1 is a block diagram showing a measurement system of a body panel molding die, which is a functional block diagram, to which an embodiment of an object measuring method according to the present invention is applied, and FIG. 2 is a measurement of the coordinate measuring machine. FIG. 3 is a configuration diagram showing a control system, FIG. 3 is an explanatory diagram illustrating a numerical model used in the measurement system, and FIGS. 4 (a) and 4 (b) are grid patterns used as reference for creating reference data used in the measurement system. And an explanatory view illustrating a striped cross-section line, FIG. 5 is an explanatory view illustrating a point sequence in the reference data, and FIG. 6 is an illustration illustrating an inclined cross-section line serving as a reference for creating the reference data. FIG. 7 is an explanatory view illustrating a point sequence in the reference data along the sectional line shown in FIG. 6, and FIG. 8 is an explanatory view showing a method of instructing a range necessary for actual measurement from the reference data, 9 and 10 show the measurement system described above. NC data for automatic measurement in the explanatory diagram illustrating the method of moving the sensor based on the present invention, FIG. 11 is an explanatory diagram illustrating the display method of the measured data during the measurement operation of the measurement system, FIG. FIG. 13 is an explanatory diagram illustrating a method of displaying measurement data after the measurement operation is completed in the measurement system, and FIG. 13 is an explanatory diagram illustrating a method of enhancing measurement data. 1 ... Host computer 2 ... Mini computer, 3 ... Three-dimensional measuring machine 4-7 ... CAD section, 8 ... Reference data creation section 17 ... Error amount calculation section 18 ... NC data creation section for measurement 20 …… Measurement data correction unit, 23,24 …… Input / output terminal device 25 …… XY plotter 27 …… Measuring machine main unit 28 …… Sensor movement control device 29 …… Current position calculation device 32,33 …… Sensor

Claims (1)

[Claims] 1. A measurement position from a signal output by a sensor contacting an object by moving the sensor from the measurement position toward an object while sequentially moving the sensor to a plurality of predetermined measurement positions. When repeatedly performing the approach procedure of measuring the position of the target object, the sensor does not contact the target object even if the sensor is moved to a predetermined position in the process of the approach procedure at one of the measurement positions. A method of measuring an object, characterized in that the approach procedure is performed for the next measurement position when the signal shown is not output.