JPH03192405A - Digitized data error correcting device for digitizing device - Google Patents

Abstract

PURPOSE:To correct the error of digitized data as the displace output of a tracer head at a part, where a shape is abruptly changed, and to enable error correction with high accuracy by providing an abruptly shape changing point decision processing part and a correction amount calculation processing part. CONSTITUTION:An abruptly shape changing point decision processing part 110 reads a displace amount SA from a tracer head 5 and according to the change rate of the read displace amount, it is decided whether the shape is abruptly changed at the that point or not. A correction amount calculation processing part 120 calculates a correction value based on data SC of X, Y and Z axes in the model shape, to which a delay processing is executed by a detection data processing part 100, and the output of the the abruptly shape changing point decision processing part 110, and the correction value is added to the model shape data SC to which the delay processing is executed. At a digitizing data processing part 6, a tolerance processing, etc., is executed to corrected model shape data SD and the data are compressed and transformed to a numerical value control program form. Thus, at the point where the shape is abruptly changed, the correction can be executed with high accuracy corresponding to a characteristic and scanning velocity provided for a stylus.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a digitizing device that generates model shape data by adding the displacement amount of each axis obtained by scanning the model surface and the detected position value of each axis. This invention relates to an improved digitized data error correction device.

Conventional technology A tracer head movement delay correction device in a digitizing device is disclosed in Japanese Patent Application Laid-Open No. 1-16454, which was previously proposed by the applicant Tsutsumi.
No. 2 is known. This is designed to correct the error (Fig. 5) that occurs when the tracer head that scans the model surface cannot completely follow the part of the model that suddenly changes shape (Fig. 4) due to physical movement delay. This is what was done. In other words, when obtaining the shape data of the model from the displacement amount of each axis and the detected position value of each axis obtained by scanning the tracer head, the movement of the tracer head included in the displacement amount of each axis and the detected position value of each axis. A delay means for correcting the difference in operation delay between each axis by delay processing the displacement amount of each axis in order to correct the delay, and a delay means for correcting the difference in operation delay between each axis, and delay processing for the position detection value of each axis to calculate the displacement amount of each axis. a delay means for correcting to match the delay time of each axis, an adding means for adding the corrected displacement amount of each axis and the corrected position detection value of each axis, and a delay means for adding the corrected displacement amount of each axis and the corrected position detection value of each axis, and It is composed of filter means for removing each vibration component, and almost satisfactory results were obtained as shown in Fig. 8 of the masterpiece.

Problem to be Solved by the Invention However, since the vibration component at the point of sudden shape change is not completely corrected, the remaining vibration component is magnified when large errors are likely to occur, such as with a small diameter stylus or a long stylus. When the error becomes large and even higher precision is required, it is necessary to correct the minute vibration component, and a problem arises in that the above-mentioned means alone cannot sufficiently correct the vibration.

The present invention has been made in view of the above-mentioned problems of the conventional technology, and its purpose is to more fully correct errors in digitized data caused by vibrations in the displacement output of the tracer head at parts with sudden shape changes. This is an attempt to develop a highly accurate error correction device.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a digitizing device that includes a shape sudden change point determination processing unit that determines a shape sudden change point from an output signal obtained by scanning a model surface with a tracer head. , calculating and adding an error correction amount of a sudden change point for the data based on the output of the sudden shape change point determination processing unit and the shape data of the model obtained based on the displacement amount of each axis and the detected position value of each axis; and a correction amount calculation processing section that creates model shape data corrected through processing. Preferably, the error correction amount is calculated using a correction formula using coefficients determined by the automatic deflection correction operation of the digitizing device.

The action tracer head determines the sudden shape change point based on the change in the displacement amount of each axis at the sudden change point of the model during scanning, and uses the output and the model shape data from the displacement amount of each axis and the detected position value to determine the model shape data. The error correction amount is calculated and addition processing is performed to obtain corrected data for NC machining of the model.

Example The following description will be made based on FIGS. 1 and 2.

In a known digitizer, a model M is fixed to a table placed on a head 1 so as to be movable and controllable in the X-axis direction. A tracer head 5 is mounted on the top beam 4 of the column 3 installed on both sides of the head, and is controlled to move in the X-axis direction by a feed screw (not shown) rotated by a motor 6.
The model M is scanned and its position is detected by the position detector 7.
The position detection value SB is output. Furthermore, the X-axis position of the table 2 and the Z-axis position of the tracer head 5 are detected, and the tracer head 5 has a stylus that traces the top of the model M, and the displacement SA in the X, Y, and Z axis directions is output. Then, based on the displacement SA and the detected position value SB, the motor 6
A digitizing control device 9 is provided which drives the components and has a deflection rate calculation processing section. Further, from the displacement 1isA from the tracer head 5 and the position detection value SB from the position detector 7 etc., a detection data processing unit 100 that creates model shape data SC, and a displacement amount SA of the tracer head 5 are provided.
A sudden shape change point determination processing section 110 determines the extent l at which the shape of the model suddenly changes from 1 to 2, and an error correction amount for SC is calculated using the model shape data SC of the detected data processing section 100 and the output of the sudden shape change point determination processing section 110. A correction amount calculation processing unit 120 creates model shape data SD corrected by addition processing, and compresses the corrected model shape data SD by tolerance processing etc., converts it into a numerical control program format, and outputs it to the auxiliary storage device 11. A digitized data processing section 10 is also provided.

The detected data processing section 100 is composed of a delay circuit and an adder as disclosed in Japanese Patent Application Laid-Open No. 1-164542. That is, a first delay circuit group that delays the displacement amounts of the x, y, and z axes from the tracer head 5, and a second delay circuit group that delays the position detection values of the X, Y, and Z axes of the position detector; 1st. and an adder that adds the data of the second delay circuit group, respectively.

The sudden shape change determination processing section 110 includes a displacement N reading section 111 that reads the displacement IsA from the tracer head 5, a sudden shape change detection section 112 that determines whether or not it is a sudden shape change point based on the rate of change of the read displacement amount, and a reference. It is comprised of a sudden shape change processing section 113 that stops when a rate of change greater than the value occurs and restarts the correct operation, and a sudden shape change data deletion section 114 that deletes unnecessary data at sudden shape change points.

The correction amount calculation processing section 120 calculates a correction value based on the data SC of the X, Y, and Z axes of the model shape delayed by the detection data processing section 100 and the output of the sudden shape change point determination processing section 110. 121 and a correction amount adder 122 that adds the correction value of the correction amount calculation section to the delayed model shape data SC.

It has been found from experimental data that the error characteristics of a sudden change in shape can be expressed by a sine wave that attenuates over time (Fig. 7). It has been found that the gain with respect to frequency differs depending on the scanning speed depending on the shape of the stylus, but by changing the scanning speed with styli of various shapes and measuring the output characteristics of the part where the shape suddenly changes, we can calculate the deflection rate (rigidity) of the stylus. A correction formula can be determined using the scanning speed and scanning speed as parameters. The deflection rate is determined by the automatic deflection correction function of the digitizing device (the stylus is brought into contact with the reference block and pressed by a certain amount of displacement output, and the ratio of the amount of change in the detector to the amount of change in the displacement output of the tracer head at that time) Since the scanning speed at that time is known, the correction amount can be calculated using the following correction formula. The correction formula can be expressed by the following formula.

Δ-Kl(δ)・Kz(V)Ks(t)K4-3in
(ωt) Kl (δ) 2 (V) for the coefficient determined by the deflection rate of the Ni stylus; 3 (t) for the coefficient determined by the Niscanning speed.
) : damping coefficient, : coefficient determined by model shape (displacement ratio of each axis) ω-2πδ, δ deflection rate of stylus (coefficient determined by rigidity) Note that instead of filter processing, output signal and detector output +
By setting the displacement output to +Δ, the correction amount is calculated from the coefficient calculated from the actual measurement data, and it becomes possible to perform highly refined correction without sacrificing responsiveness.

Next, a description will be given based on FIG. 3, which is a flowchart for creating digitized data.

In step S1, an automatic deflection correction operation is executed, and the deflection rate of the stylus 8 is measured by the deflection rate calculation processing section of the digitizing control device 5.

In step S2, Ks, ω, which is determined by the K deflection correction value which is equal to the deflection correction value, and which is a previously measured empirical value, is calculated by the deflection rate calculation processing section in the digitizing control device 9 when automatic deflection correction is executed, and is used as a parameter. It is stored in the memory of the digitizing control device 9.

In step S3, the motor 6 and the like are driven to scan the model M with the tracer head 5.

In step S4, it is determined whether or not it is a sudden shape change point based on the rate of change in the amount of displacement of the model shape data SA input to the shape sudden change point determination processing section 110. YES here
If so, it is determined in step S5 whether the data at the sudden shape change point is to be deleted. If NO, it is determined in step S6 whether the attenuation time or attenuation distance is within the correction range determined by the parameters based on the fluctuation of the output signal experienced. If YES, in step S7, the correction amount calculation section 122 of the correction amount calculation processing section 120 calculates 2, which is a coefficient for correcting the magnitude of the error amount depending on the scanning speed, based on the previously measured empirical value. The calculation is then stored based on the scanning speed of each axis at that time. Further, the correction amount calculation processing section 120 calculates and stores 4 as the ratio of the displacement amount output of each axis to the displacement amount output at that time.

In step S8, the correction amount Δ=(δ)・K
g(V) ・Ks(t) ' Ka ・5in(ω
t), the correction amount Δ is calculated and stored.

In step S9, a correction amount Δ is further added to the model shape data created based on the output of the detector 7 and the output of the tracer head 5.

In step 310, the digitizing data processing unit 6
In the step, the corrected model shape data SD is subjected to tolerance processing and the like, compressed, and converted into a numerical control program format.

The converted value is stored in the auxiliary storage device 7 in step Sll.

If the determination in step S4 is "No" in the previous step S4 as to whether the shape is a sudden change point, and if the determination in step S6 is "no" in the correction range, the correction process is deemed unnecessary and the process moves to step SIO. Also, in step S5, Y
If it is ES, the process moves to step S12.

In step S12, a comparison is made to see if the scanning on the model M has been completed over the entire range. If YES, it is completed, and if NO, the process moves to step S4 and the correction process is executed again.

Effects Since the invention has been achieved as described above, the present invention has the following effects.

At sudden shape change points, highly accurate correction corresponding to the characteristics of the stylus and scanning speed is possible, increasing the scanning command speed, improving the accuracy of NC data, and shortening the time to collect model shape data. It is something that can be done.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the tracer head movement delay correction device in the digitizing apparatus of the present invention, FIG. 2 is a block diagram of the correction amount calculation processing section and the sudden shape change point determination processing section, and FIG.
The figure is a flowchart of digitizing data creation, Figure 4 is a diagram showing sudden changes in model shape, Figure 5 is a diagram of the digitizing output signal in Figure 4, and Figure 6 is a diagram of the detector output and signal when the filler collides with a wall. A diagram showing the relationship between the output time and Fig. 7 is a diagram of the relationship between the detector output + displacement output and time, and Fig. 8 is a diagram of the relationship between the detector output + displacement output and time.
FIG. 9 is a diagram showing the relationship between the output after the delay corrector filtering process is performed by the correction device of No. 164542 and time, and FIG. 5...Tracer head 100...Detection data processing section 110...Shape abrupt change point determination processing section 120...Correction amount calculation processing section Fig. 4

Claims (2)

[Claims] (1) In a digitizing device, the tracer head (
5), a shape sudden change point determination processing unit (110) that determines a shape sudden change point from the displacement output of each axis obtained by scanning the surface of the model (M), and an output of the shape sudden change point determination processing unit and each of the axes. and the shape data of the model obtained based on the displacement amount of the axis and the position detection value of each axis, and calculate the error correction amount of the sudden change point with respect to the data, and create corrected model shape data by addition processing. NC based on the corrected model shape data.
A digitized data error correction device in a digitizing device that creates processing data. 2. The error correction device for digitized data in a digitizing device according to claim 1, wherein the error correction amount is calculated by a correction formula using a coefficient determined by an automatic deflection correction operation of the digitizing device.