JPH0388004A - Digitizing controlling device - Google Patents

Abstract

PURPOSE:To attain rapid, highly accurate and stable scanning by finding out a scanning direction in a state removing influence due to friction generated between a stylus and a model. CONSTITUTION:A stylus position coordinate and displacement reading/composing part 3 reads out scanning head positions PX, PY, PZ and change variabels epsilonx, epsilony, epsilonz obtained from an machine position detector (not shown in figure), finds out the center position vector Ct of the stylus S which is the sum of these values and stores the vector Ct on a stylus center position storage part 4. Then, a scanning direction calculating part 2 inputs the position vector Ct at time (t) which is obtained from the composing part 3 and a position vector Ct- t at DELTAt second before which is stored in the storage part 4 and finds out the tangent vector t' of a model M. A normal vector n' rectangular to the tangent vector t' is found out based upon a displacement vector epsilon and the tangent vector t' and the scanning speed in the vector n' direction is calculated to remove the influence due to friction generated between the stylus and the model and determined the scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a digitizing control device, and particularly to a digitizing control device that performs data compression processing such as tolerance processing on model shape data obtained by scanning a model surface with a stylus. The present invention relates to a digitizing control device that generates and outputs numerical control machining programs.

(Conventional Technology) Conventionally, when machining a complicated three-dimensional shape, a model of the three-dimensional shape was actually created and copy processing was performed by using a copy milling machine or the like to determine the model. However, in recent years, numerical control (N
C) Machining was performed using a digitizing control device that generated and output a cutting program, and an NC machine that controlled the trajectory of the tool and machined the workpiece according to the NC program.

(Problem to be Solved by the Invention) However, in the conventional digitizing control device described above, the scanning speed is considerably improved because scanning and processing are performed independently, but the scanning direction is controlled by the stylus. Since this was done based on the direction and magnitude of the displacement vector, friction resulted in a misalignment between the normal direction of the model surface and the direction of the stylus displacement vector. Therefore, it is not possible to accurately control the scanning direction, which is a problem when trying to further improve the scanning speed.

The present invention was inspired by the above-mentioned circumstances, and an object of the present invention is to further improve scanning performance by controlling the scanning direction more accurately in accordance with the shape of the model surface. An object of the present invention is to provide a digitizing control device.

(Means for Solving the Problems) The present invention performs data pressure 1ii processing such as tolerance processing on model shape data obtained by scanning the surface of the model with a stylus to generate and output a nibprogram for numerical control. The above object of the present invention is to relatively move a scanning head while keeping a stylus in contact with the surface of a model and keep the displacement constant, and to calculate the position coordinates of the scanning head and the obtained scanning head position coordinates. In a digitizing control device that outputs a numerically controlled machining program based on the displacement amount of the stylus, the tangent of the model is determined from the locus of the position vector representing the center of the stylus obtained by adding the position coordinates and the displacement amount. tangent vector calculation means for calculating a vector; normal vector calculation means for calculating a normal vector perpendicular to the tangent vector based on the displacement vector based on the displacement amount and the tangent vector; This is achieved by comprising a scanning speed calculation means for calculating a tangential component and a normal component of a scanning speed at which the scanning head should be relatively moved in a direction.

(Function) In the present invention, the model is calculated from the locus of the position vector representing the center of the stylus, which is the result of adding the position coordinates of the scanning head obtained by scanning the model surface with the stylus and the amount of displacement of the stylus. A tangent vector is calculated, a normal vector orthogonal to the tangent vector is calculated based on the displacement vector based on the displacement amount and the tangent vector, and a scanning speed is calculated in the direction of the normal vector. By doing so, the scanning direction can be determined while eliminating the influence of friction between the stylus and the model.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram of an embodiment of the digitizing control device of the present invention. In the figure, the stylus position coordinate/displacement flea reading synthesis unit 3 scans the scanning head position (Px, P
y, Pz) and the displacement amount (Ex, Ey, Ez) obtained from the scanning head H, and outputs the center position vector C0 of the stylus S, which is the sum of these, and the magnitude of the displacement amount ε. The center position vector Ct of the stylus S is stored in the stylus center position storage section 4. The scanning direction calculation unit 2 stores the center position vector C7 at time t from the stylus position coordinate/displacement reading synthesis unit 3 in the stylus center position storage unit 4. d
A tangent vector t and a normal vector n of the model M are calculated and output by manually inputting the center position vector Ct-At t seconds ago. The scanning control unit 1 inputs the displacement amount ε from the stylus position coordinate/displacement reading synthesis unit 3, the tangential vector from the scanning direction calculation unit 2, and the information on the normal vector n, and calculates the scanning speed. The servo motor 5 calculates the normal direction component vH and the tangential direction component VT, and moves the stylus S along the surface of the model M while keeping the magnitude of the displacement vector ε of the stylus S constant based on them. (lllX, MY,
Drives Mri.

FIG. 2 is a diagram showing the detailed procedure of the above-mentioned processing operation. To explain the procedure in detail based on the figure, first, the stylus position coordinate/displacement reading synthesis unit 3 reads the position vector P and displacement vector ε of the stylus S obtained from the mechanical position detector, and calculates the sum of these. The center position vector Ct of the stylus S is determined and stored in the stylus center position storage section 4 (step Sl). Next, the scanning direction calculation section 2 calculates the position vector Ct at time t from the stylus position coordinate/displacement amount reading synthesis section 3 and the position vector Ct-jt at Jt seconds ago stored in the stylus center position storage section 4. As shown in FIG. 3, the tangent vector t of the model M is manually determined using equation 11 (step S2).

t'' Ct-Ct-71t (1) Next, the scanning direction calculation unit 2 calculates the normal vector n as follows (step S3).

That is, as shown in FIG. 4, the normal vector n is expressed by equation (2) based on the displacement vector ε and the vector obtained by multiplying the tangential vector t by a predetermined value -t.

n = ε 10-t (2) Here, since the tangent vector t and the normal vector n are orthogonal, the relationship between n and t is as shown in equation (3).

・1=0 ・・・・・・・・・(3) Therefore, (2) k in the formula is expressed by formula (4) will be done.

12 Therefore, the normal vector n is (2) Formula and (4) Is it a ceremony? It is derived from Equation (5).

Since changes in the shell due to friction occur in the same direction as the moving direction of the stylus, that is, in the tangential direction, the normal vector n in equation (5) represents a displacement vector that excludes the influence of friction. Therefore, this normal vector n is closer to the normal direction of the true model than the direction of the conventional displacement vector.

Next, the scanning control unit l calculates the normal direction component vN of the scanning speed based on the magnitude of the input displacement vector ε of the stylus S with respect to the direction of the normal vector n according to equation (5). Obtained by the formula.

■N=k (ε−ε.) ・・・・・・
...(6) Also, the tangential component Va is determined by equation (7).

vT=,/”W7go□;7 ・・・・・・
...(7) Here, ε. is the reference displacement amount, and vo is the command scanning speed.

In the above embodiment, the tangent vector t is determined from the position vector C0 representing the current stylus center and the position vector Ct-Jt representing the stylus center At seconds ago, as shown in equation ('1). However, the position vector cd representing the center of the stylus that is a certain distance tBAd away from the position vector Ct representing the current center of the stylus! 4d may be calculated using equation (8).

t=Ct-cd! 4d (8) (Effects of the Invention) As described above, according to the digitizing control device of the present invention, the scanning direction can be determined while eliminating the influence of friction between the stylus and the model. This enables faster, more accurate, and more stable scanning of model shapes.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the digitizing control device of the present invention, FIG. 2 is a diagram showing the procedure of processing operation,
FIG. 3 is a diagram for determining the tangent vector, and FIG. 4 is a diagram for determining the normal vector. DESCRIPTION OF SYMBOLS 1...Scanning control unit, 2...Scanning direction calculation unit, 3...Stylus position coordinate/displacement reading synthesis unit, 4...Stylus center position storage unit, 5...Servo motor, S. ...Stylus, H...Scanning head, M...Model.

Claims (1)

[Claims] 1. The scanning head is moved relative to the surface of the model by bringing the stylus into contact with the surface of the model while keeping the magnitude of the displacement constant, and based on the obtained position coordinates of the scanning head and the amount of displacement of the stylus. In a digitizing control device that outputs a program for numerically controlled machining, tangent vector calculation is performed to calculate a tangent vector of the model from the locus of a position vector representing the center of the stylus obtained by adding the position coordinates and the displacement amount. means, normal vector calculation means for calculating a normal vector orthogonal to the tangential vector based on the displacement vector based on the displacement amount and the tangential vector; and relative movement of the scanning head in the direction of the normal vector. What is claimed is: 1. A digitizing control device comprising: scanning speed calculation means for calculating a tangential direction component and a normal direction component of a scanning speed to be applied. 2. The tangential vector calculation means is configured to subtract a position vector before a certain time or a certain distance from a certain position vector to find the locus of the position vector representing the center of the stylus. digitizing control device. 3. The normal vector calculation means calculates a vector obtained by multiplying the displacement vector of the stylus and the connection vector of the model by a predetermined value such that the normal vector and the tangent vector to be obtained form a right angle. The digitizing control device according to claim 1, wherein the normal vector is obtained by adding.