JPH089134B2 - Gradient correction method for three-dimensional scanning - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gradient correction method in three-dimensional scanning when correcting data of a gradient portion of the model in three-dimensional scanning of a model surface with a stylus.

(Technical background and problems to be solved) In order to machine a 3D model using an NC (numerical control) machine tool, a stylus is brought into contact with the 3D model surface and the Data created by controlling the copying operation is necessary.

In the three-dimensional copying control method in this copying operation, the one-dimensional copying control and the two-dimensional copying control are combined and processed simultaneously.

Regarding the above-mentioned respective-dimensional copying control, FIG.
This will be described with reference to (B) and FIG.

FIG. 5A shows a one-dimensional scanning control, and a three-dimensional model.
Touch the stylus 43 to the floor surface 11 of 10 and NC in the XY direction.
It is operated under control (arrow a in the figure). Three-dimensional model
When the floor surface 11 of 10 has irregularities, the drag force (the arrow b in the figure) that the stylus 43 receives from the floor surface 11 of the three-dimensional model 10, that is, the amount of displacement changes. Therefore, the stylus 43 is moved up and down in the Z-axis direction so as to keep this displacement constant (Fig. (B)).
As a result, position data equivalent to changes in the three-dimensional model 10 and the floor surface 11 can be obtained.

FIG. 6 shows the two-dimensional scanning control, in which the stylus 43 is brought into contact with the wall surface 21 of the three-dimensional model 20, and the stylus 43 is operated on the XY plane while keeping the coordinate values of the Z axis constant.
At this time, both the direction and the magnitude of the amount of displacement (arrow C in the figure) that the stylus 43 receives from the wall surface 21 of the three-dimensional model change. Since this direction is always perpendicular to the wall surface 21 of the three-dimensional model 20, the stylus 43 is moved in the direction perpendicular to the direction of displacement so that the magnitude of displacement is constant.
By operating in the plane, one X of the 3D model 20
-Position data in the Y plane can be obtained. 2
There are various kinds of dimensional copying, such as surface copying, but the idea is the same.

The three-dimensional scanning control is performed by the above-described one-dimensional and two-dimensional scanning control and a combination thereof, that is, the stylus 43 is a wall surface or floor
Positional data is obtained by operating the stylus 43 so that the amount of displacement on the XY plane generated from the wall surface and the amount of displacement in the Z-axis direction generated from the floor are constant at the portions that come into contact with each other at points. be able to.

For example, in the case of a three-dimensional model 30 in which a rectangular column-shaped model 31 having one slope (floor surface 311) and a cylindrical column-shaped model 32 shown in FIG. 7 are combined, the rectangular column-shaped model 31 and the cylindrical column-shaped model 31 are used. The position data of each model 32 can be obtained by the method described above. However, when following the connecting boundary line between the square columnar model 31 and the columnar model 32 of this model 30,
Since the traveling direction of the stylus 43 is inclined, the displacement amount from the inclined floor surface 311 is included in the displacement amount component on the XY plane.

In order to make this clearer, a supplementary explanation will be given with reference to FIG. 8 for explaining the displacement amount on the XY plane due to the inclined floor surface in the three-dimensional copying. FIG. 8A shows the displacement amount when the stylus 43 comes into contact with the wall surface 82 of the model 81 and the inclined floor surface 83 to perform the copying operation. Arrow α
Indicates the amount of displacement by the wall surface 82, and the arrow β indicates the amount of displacement by the floor surface 83. The arrow β is generated at a right angle to the floor surface 83, and the arrows γ and δ are divided as displacement amounts on the Z axis and XY plane, respectively. An arrow ε is a combination of the displacement amounts α and δ on the XY plane, and indicates the displacement amount generated on the XY plane when the wall surface 82 and the floor surface 83 are moved.

8B and 8C are views of FIG. 8A viewed from the Z-axis direction, and arrows 85 and 87 indicate the direction of the copying operation.
In FIG. 8 (B), the copying is in a climbing direction with respect to the floor surface 83, and the copying direction is a direction of an arrow 84 perpendicular to the displacement amount ε, and moves in a direction away from the wall surface 82. Floor in Fig. 8 (C)
The arrow is a downward profile to 83, and an arrow that bites into the wall 82
Operates in 86 directions.

Therefore, as described above, in the three-dimensional scanning control, when the floor surface is inclined, the stylus 43 bites and separates, which causes unstable scanning control.

(Object of the Invention) The present invention has been made under the circumstances as described above,
It is an object of the present invention to provide a gradient correction method in three-dimensional scanning in which the displacement amount is corrected by obtaining the gradient of the three-dimensional model from the change in the current position and stable three-dimensional scanning control can be performed. is there.

(Means for Solving Problems) The present invention relates to a gradient correction method in three-dimensional scanning of a model having a gradient, and an object of the present invention is to read position data and displacement amount data of the model, This is achieved by obtaining a correction amount corresponding to the gradient based on the direction ratio of the movement amount of the current position obtained from the change in the data, and correcting the displacement amount data with this correction amount.

(Operation of the Invention) The present invention is such that the correction amount corresponding to the gradient is obtained from the direction ratio of the movement amount of the current position, and the displacement amount data can be corrected by this correction amount.

(Embodiment of the Invention) FIG. 1 is a block diagram showing an embodiment of an apparatus for realizing a gradient correction method according to the present invention.

The device comprises a mechanical section 40 and a control section 50. Machine part 40
Is composed of a stylus 43 that operates the tracer head 42 by the motor 41 to copy the surface of the model 30 and a position detector 44 that detects the position data of the model 30. The control unit 50
Position reading unit 51 for reading position data of model 30, model 30
Displacement reading unit 52 for reading the displacement amount data, a three-dimensional scanning correction amount calculation unit 53 for correcting the displacement amount from the position data and the displacement amount data, and the moving direction of the stylus 43 is calculated from the corrected displacement amount It is composed of a three-dimensional scanning calculation unit 54 and a motor control unit 55 that outputs data on the moving direction to the mechanical unit 40 and drives the motor 41.

Next, the three-dimensional model 30 shown in FIG. 3 and the arrows in the figure.
Fig. 4 (A), (B), which shows the view seen from the A, B, and C directions,
A flowchart for explaining the present invention shown in FIG. 2 will be described with reference to FIG.

Here, for the sake of simplicity, the wall surface of the three-dimensional model 32
Assume 1 is vertical. When the connecting boundary line of the three-dimensional model 30 is traced in the direction of arrow d in FIG. 3, the stylus 43 contacts the vertical wall surface 321 and the sloped floor surface 311 and generates displacement amounts from both. Here, the displacement amount is represented by ε, the displacement amount from the wall surface 321 is S, the displacement amount from the floor surface 311 is F, and the displacement amounts from the X, Y, and Z axis directions are X, Y, and Subscript Z.

First, the displacement amount (ε _X , ε _Y , ε _Z ) is read from the stylus 43 into the displacement amount reading unit 52 (step S1), and the current position (AP
A _XT , APA _YT , APA _ZT ) are read into the position reading unit 51 (step S2). The amount of displacement ε _F from the floor surface 311 and the amount of displacement ε _S from the wall surface 321 are expressed by the following equations as is clear from FIGS. 4 (A), (B) and (C).

As is clear from equation (1), the displacement amount ε _F from the floor surface 311 is X
The displacement amount component ε _FXY on the −Y plane is included. Therefore, if the displacement amount in the Z-axis direction that is controlled to be always constant is ε _ZO , ε _FZ is expressed by the following equation.

ε _FZ = ε _ZO (2) Therefore, if the displacement amount component ε _FXY on the XY plane is the angle (tilt angle) θ that the floor surface 311 makes with the horizontal plane, the following equation is obtained from FIG. 4 (B). It is represented by.

ε _FXY = -ε _FZ · tan θ = –ε _ZO · (Z movement amount / X-Y plane movement amount) (3) Then, (Z movement amount / X-Y plane movement amount) is calculated Therefore, the direction ratio of the movement amount of each axis is obtained. Position at time T _O (APA _XO , APA _YO , APA _ZO ), position at time T _O + T _I (A
PA _XI , APA _YI , APA _ZI ), the direction ratio of the movement amount of each axis
U, V and W are expressed by the following equation (step S3).

U: V: W = (APA _XI −APA _XO ) :( APA _YI −APA _YO ) :( APA _ZI −APA _ZO ) …… (4) That is, Next, check whether the copying surface has a gradient (step S
4) If not, go to step S7. On the other hand, if there is a gradient in the determination step S4, the following equation is derived from the equations (3) and (5).

_Dividing this ε _FXY into components in the X and Y axis directions _{gives the} following equation. The angle between ε _FXY and the X axis (ε _FX ) is α, as shown in FIG. 4 (A).

When cos α and sin α in the equation (7) are represented by the direction ratio of the movement amounts of the X and Y axes, the following equation is obtained.

Therefore, the following equation is derived from the equations (6) and (8) (step S5).

From the above, the displacement amount component ε _FXY of the displacement amount ε _F from the floor surface 311 on the XY plane can be obtained from the direction ratio of the movement amount of the stylus 43 at the current position.

Next, the actually detected displacement amounts (ε _X , ε _Y , ε _Z ) ε _X and ε _Y are corrected to ε _X ′ and ε _Y ′, respectively, as shown in the following equation (step S6).

By correcting as in equation (10), it is possible to control as if the apparent floor surface had no slope.

Then, the movement direction of the stylus 43 is calculated using the displacement amounts ε _X ′ and ε _Y ′ corrected by the three-dimensional scanning calculation unit 54 (step S7), and the calculated data is transferred to the motor control unit 55 (step S7). S8), the mechanical section 40 by the motor control section 55
The motor 41 is driven to control the scanning of the stylus 43.

Although the case where the wall surface of the model is vertical has been described above, the same correction can be performed even if the wall surface is inclined.

(Effects of the Invention) As described above, according to the method of the present invention, when the three-dimensional model has an arbitrary gradient, it is possible to perform a scanning operation that does not cause the stylus to bite or separate, and stable three-dimensional scanning control can be performed. become able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of an apparatus for implementing the method of the present invention, FIG. 2 is a flow chart for explaining the operation of the method of the present invention, FIG. 3 is a perspective view showing an example of a three-dimensional model, and FIG.
(A), (B) and (C) are vector diagrams of the displacement amount for explaining the method of the present invention, and FIGS. 5 (A) and (B) are diagrams for explaining the one-dimensional scanning control method, and FIG. Is a diagram for explaining a two-dimensional scanning control method, FIG. 7 is a diagram for explaining a three-dimensional scanning control method, and FIGS. 8 (A), (B), and (C) are distances for copying an inclined surface, It is a figure explaining a biting phenomenon. Reference numeral 51 ... Position reading unit, 52 ... Displacement amount reading unit, 53 ... Three-dimensional scanning correction amount calculation unit, 54 ... Three-dimensional scanning calculation unit, 55 ... Motor control unit.

Claims (1)

[Claims] 1. In the three-dimensional scanning of a model having a gradient, the position data of the model and the displacement amount data in the XY direction and the Z direction are read, and the XY of the displacement from the floor due to the gradient is read.
The directional component is calculated by calculating the direction ratio of the movement amount of the current position obtained from the change of the position data, and the displacement amount data in the XY directions is corrected using this as a correction amount. Gradient correction method in dimensional copying.