JP2003076410A - Speed control device, speed control method and program for carrying the method with computer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed control device and a speed control method capable of securely reducing the passing speed at a position necessary to reduce the passing speed and capable of deciding the passing speed in relation to a sequence of points having a moving trajectory adjacent to each other with a different arrangement, and to provide a program for carrying this method out by computing a curvature for smoothening an error included in the sequence of points to compute a proper curvature strong against the error included in the sequence of points even if a distance between the points of the sequence of points is fine. SOLUTION: Command position data in continuous four points is used to compute a curvature of a moving trajectory on the basis of a vector connecting the two points of the first half and a vector connecting the two points of the second half, and passing speed of a tool is decided by using the computed curvature and the allowable acceleration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control device and a speed control device capable of appropriately obtaining a curvature required for determining a feed speed when machining a free-form surface using an NC machine tool or a robot. The present invention relates to a control method and a program for executing the method.

[0002]

2. Description of the Related Art A shape having a free-form surface such as a mold is
When machining with a numerical control (NC) machine tool, a method is used in which a free curve is divided into minute sections to form minute line segment data, and a movement path is interpolated and controlled using these line segment data.

In such a method, the command data N
The C program is composed of a command feed speed and a series of minute line segment data (blocks). The NC control device analyzes each minute line segment data, determines whether or not the trajectory can be followed within the allowable acceleration of the machine, and limits the passing speed (feed speed) to the command feed speed or less as necessary. I do.

As one of the methods of limiting the passing speed in this way, there is a method of limiting the passing speed by using the curvature of the moving path and the allowable acceleration of the machine. Such a method is disclosed in JP-A-2-110711 or JP-A-2-21910.
No. 7 publication.

In Japanese Patent Laid-Open No. 2-110711, the radius of a circle passing through the three consecutive points of the machining position data group is calculated, and the machining dimension error is made constant from the calculated radius of the circle. An invention is disclosed in which the processing speed is calculated under the conditions.

In Japanese Patent Laid-Open No. 2-219107, the curvature of a section is calculated by using a line segment vector of two consecutive sections (blocks) formed by a sequence of points and a moving speed of the section. An invention is disclosed in which the moving speed is limited so that the normal acceleration determined accordingly becomes equal to or less than an allowable value.

In this way, limiting the passing speed is called "clamping", the position to be clamped is called the clamp position, and the passed speed that is clamped is called the clamp speed.

After the passing speed is determined by the above method or the like, if the clamp position is a predetermined distance or more from the current point, it is not necessary to decelerate, so the movement amount (f expressed by the command speed f × sampling time Δt X Δt) continues to interpolate the minute line segment block, and when the clamp position is detected within a predetermined distance, the acceleration / deceleration device allows the clamp position to pass at the clamp speed in advance from the point before the clamp point every sampling cycle. The deceleration is performed within the allowable acceleration, and the minute line segment block is interpolated by the movement amount represented by the speed f ′ × Δt that is subjected to the acceleration / deceleration processing.

As described above, current servo system control devices such as NCs are equipped with a function of evaluating the commanded trajectory shape by some means to determine the passing speed.

[0010]

By the way, when the smoothness and the continuity of the machined surface are important as in the die machining, the continuous change of the loci adjacent to each other at a predetermined feed pitch (pick feed). Is required. For this purpose, for example, as shown in FIG. 8, if a point P _i on one of the trajectories T _i is determined to be a corner and decelerated, the trajectories T having adjacent trajectories with a very small feed pitch and having substantially the same shape. _{i + 1} of the even points Q _i near P _i, it is necessary to decelerate is determined similarly to the corner.

As described above, in order to operate the NC machine tool, it is necessary to create an NC program, and when a die is targeted, a CAM (Computer outside the NC device is used).
It is common to create an NC program with an Aided Manufacturing system. In the CAM system, the locus, which is ideally a free-form curve, is approximately divided into blocks divided into minute line segments so as to keep the tolerance desired by the user. It is normal that there are variations.

However, in the former prior art, since an arc is applied to three consecutive points and the radius thereof is used as the radius of curvature for shape evaluation of the movement trajectory, it is sensitive to the error of the point sequence. . Therefore, if the point sequence includes an error, it is directly reflected in the calculated curvature, and a completely different processing result may be obtained from the curve to be processed.

FIG. 9 is a diagram for explaining a defect of the former prior art described above. As shown in FIG. 9, a series of points P ₀ , P ₁ , on the locus, which is ideally an arc represented by a broken line,
Consider the case where the third point P _{2 of} P ₂ , P ₃ , ... Departs from the target locus due to the above error. In the prior art, for example, as shown in FIG.
In the set of points P ₀ , P ₁ and P ₂ , the arc center ct ₁ is located on the side opposite to the side having the ideal arc center ct, and the arc radius is considerably large. In the subsequent set of three points P ₁ , P ₂ and P ₃ , the arc center ct ₂ is located on the same side as the ideal arc center ct as shown in FIG. 9B, but the arc radius is small. From this, it can be seen that the former conventional method is a curvature calculation method that is sensitive to the error contained in the point sequence. In the method of calculating the curvature that is greatly influenced by such an error, the goal of equalizing the passing speeds on the adjacent trajectories cannot be achieved as described above, and as a result, a smooth machined surface cannot be obtained.

Next, in the latter prior art, three consecutive
Since the moving speed is limited by obtaining the speed difference between two consecutive blocks composed of points, the smaller the block unit of the minute line segment block, the more difficult it is to limit the passing speed. have. In other words, since the precision machining is required in the recent die machining, the minute line segment output by the CAM system tends to be further miniaturized, and the angle between two consecutive blocks becomes small. In contrast to this tendency, the latter conventional technique has a problem that it is difficult to limit the passing speed, the passing speed exceeds the allowable acceleration of the machine, and as a result, the machined surface becomes dirty.

The present invention has been made in view of the above,
By calculating the curvature that can smooth the error included in the point sequence, it is possible to calculate the appropriate curvature that is strong against the error included in the point sequence and even if the distance between the point sequences is small, thereby reducing the passing speed. Execute a speed control device, a speed control method, and a speed control method capable of surely decelerating the passing speed at a position to be performed and determining the passing speed in the same way even for point sequences having different arrangements on adjacent movement loci. The purpose is to get a program to do.

[0016]

In order to achieve the above object, a velocity control device according to the present invention is a curvature calculating section for calculating a curvature of a tool locus by using command position data of each point of a point sequence showing the tool locus. And a passing speed determination unit that calculates a passing speed based on the calculated curvature and the allowable acceleration of the machine,
The curvature calculation unit may calculate the curvature of the movement trajectory by using command position data for four or more consecutive points in the position data representing the tool trajectory.

According to the present invention, the curvature of the movement locus is calculated using the commanded position data for four or more consecutive points in the position data representing the tool locus.

In the speed control device according to the next invention, in the above invention, the curvature calculating unit uses the command position data of four continuous points, and a vector connecting the first two points and a vector connecting the second two points. The curvature of the movement trajectory is calculated based on

According to the present invention, the curvature of the movement locus is calculated based on the vector connecting the two points in the first half of the four continuous points and the vector connecting the two points in the latter half.

A speed control device according to the next invention comprises a curvature calculating section for calculating a curvature of a tool path by using command position data of each point of a point sequence showing a tool path, a calculated curvature and an allowable acceleration of a machine. And a passage speed determination unit that calculates a passage speed based on the above, and the curvature calculation unit is present after the first point on the rear side of the point sequence section whose current passage speed is to be determined and after the first point. By generating a vector that connects adjacent points in a plurality of point sequences, and recursively generating a vector that connects each point obtained by dividing these vectors at a predetermined ratio between the adjacent points, One first vector is generated after the point, and a vector connecting the second point on the front side of the point sequence section and the adjacent points in the plurality of point sequences before the second point is generated, Furthermore, those vectors One second vector is generated before the second point by recursively generating a vector in which each point divided at a constant ratio is connected between adjacent points, and the generated first and second vectors are generated. It is characterized in that the curvature of the movement trajectory is calculated using the vector of 2.

According to the present invention, the first point on the rear side of the point sequence section whose current passage speed is to be determined and the first point
Generates a vector that connects adjacent points in a sequence of points that exist after point, and recursively creates a vector that connects each point obtained by dividing those vectors at a predetermined ratio. As a result, one first vector is generated after the first point, and a second point on the front side of the point sequence section and an adjacent point in a plurality of point sequences before the second point are connected. Second vector is generated by recursively generating a vector in which each point obtained by dividing the vector by a predetermined ratio is connected to the adjacent points.
One second vector is generated before the point, and the curvature of the movement trajectory is calculated using the generated first and second vectors.

In the speed control method according to the next invention, the first step of calculating the curvature of the tool path by using the commanded position data of each point of the point sequence indicating the tool path, the calculated curvature and the machine allowance. A second step of calculating a passing speed based on the acceleration, and in the first step, the curvature of the movement trajectory is calculated using command position data for four or more consecutive points in the position data representing the tool trajectory. It is characterized by doing.

According to the present invention, the curvature of the movement locus is calculated using the commanded position data for four or more consecutive points in the position data representing the tool locus.

In the speed control method according to the next invention, in the above invention, in the first step, the continuous 4
It is characterized in that the curvature of the moving locus is calculated based on a vector connecting two points in the first half and a vector connecting two points in the latter half using command position data of the points.

According to the present invention, the curvature of the movement locus is calculated based on the vector connecting the first two points of the continuous four points and the vector connecting the second two points.

In the speed control method according to the next invention, the first step of calculating the curvature of the tool path by using the commanded position data of each point of the point sequence indicating the tool path, the calculated curvature and the machine tolerance. A second step of calculating a passing speed based on the acceleration, and in the first step, a first point on the rear side of the point sequence section whose current passing speed is to be determined and after the first point. By generating a vector connecting adjacent points in a plurality of existing point sequences, and recursively generating a vector connecting each point obtained by dividing these vectors at a predetermined ratio between the adjacent points, One first vector is generated after one point, and a vector connecting the second point on the front side of the point sequence section and the adjacent points in the plurality of point sequences before the second point is generated. And then those One second vector is generated in front of the second point by recursively generating a vector in which each point obtained by dividing the cuttle at a predetermined ratio is connected between adjacent points, and the generated first vector is generated. And calculating the curvature of the movement trajectory using the second vector.

According to the present invention, the first point on the rear side of the point sequence section whose current passage speed is to be determined and the first point
Generates a vector that connects adjacent points in a sequence of points that exist after point, and recursively creates a vector that connects each point obtained by dividing those vectors at a predetermined ratio. As a result, one first vector is generated after the first point, and a second point on the front side of the point sequence section and an adjacent point in a plurality of point sequences before the second point are connected. Second vector is generated by recursively generating a vector in which each point obtained by dividing the vector by a predetermined ratio is connected to the adjacent points.
One second vector is generated before the point, and the curvature of the movement trajectory is calculated using the generated first and second vectors.

A program according to the next invention is a program for causing a computer to execute the method described in any one of the above inventions, and the program becomes computer readable, whereby any one of the above inventions can be realized. An operation can be performed by a computer.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a speed control device, a speed control method, and a program for causing a computer to execute the method will be described in detail below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a block diagram showing an example of Embodiment 1 of the present invention. The speed control device of the present invention is incorporated in the control device as a part of a numerical control device, a robot control device, etc., but in FIG. 1, the minimum of the functions of these control devices necessary for showing the features of the present invention. Only the functional part is shown. That is, in the first embodiment, the speed control device includes the point sequence output unit 10 and the curvature calculation unit 2.
0, a point sequence buffer 30 and a passage speed determination unit 40.

The point sequence output unit 10 receives command position data (trajectory) of each point of the point sequence indicating the tool trajectory from an external CAM system (not shown) or a trajectory data creation unit (not shown) inside the control device. Data) P and command feed speed data f are input. In the external CAM system, locus data, command feed speed, etc. are created, and these are input to the point sequence output unit 10 via the command data output unit. The locus data creation unit inside the control device creates locus data from the curved surface model and the tool model, and inputs the created locus data or the set command feed speed to the point sequence output unit 10. The point sequence output unit 10 sequentially outputs the command position data (trajectory data) P and the command feed speed data f of each input point sequence to the curvature calculation unit 20.

The curvature calculating section 20 is a constituent element of the main part of the present invention, and has a point sequence buffer 30 capable of storing point sequence data (command position data) of at least four points. The point sequence buffer 30 adopts a first-in first-out method and holds four command position data so that the command position data of the point just received always exists at the end of the buffer. The curvature calculation unit 20 uses the command position data P of the four points stored in the point sequence buffer 30 to calculate the curvature κ of the movement trajectory.
Is calculated. In this case, the curvature calculation unit 20 calculates the command position data of the four points stored in the point sequence buffer 30.
Two velocity vectors, a velocity vector connecting the first two points and a velocity vector connecting the second two points, are calculated, and the curvature is calculated based on the obtained two velocity vectors.

A method of calculating the curvature using the position data of these four points will be described. FIG. 2 is for explaining the first method of calculating the curvature using four points. Let P (s) be the curve with the curve length s as the parameter, and l be the chord length parameter.
Then, the curvature κ of this curve can be expressed by the following equation (1).

[Equation 1]

Here, the curve and the chord can be sufficiently approximated (ds
≈dl), the equation (1) can be expressed as the following equation (2) in the minute section (s ₀ ≦ s ≦ s ₀ + ds).

[Equation 2]

Equation (2) represents how the directions of the two unitized velocity vectors q (s ₀ + ds) and q (s ₀ ) change while moving the distance dl. By giving the vector and the distance dl, the curvature can be estimated according to the above equation (2).

In the first method, as shown in FIG. 2, as a unitized velocity vector, a unit vector u ₀ of a vector V ₀ from a point P ₀ to a point P ₁ and a point P ₂ to a point P. The unit vector u ₁ of the vector V ₂ to ₃ is given, and the length dl of the vector from the point P ₁ to the point P ₂ is given as the distance dl.

Further, in the second method, as shown in FIG. 3, two unitized velocity vectors are used. The unit vector u ₀ of the vector V ₀ from the point P ₀ to the point P ₁ and the point P _{2 are obtained.} given unit vector u ₁ of the vector V ₂ to the point P _3, as the distance dl, from the midpoint P ₄ of P ₀ and P _1, gives the length of the vector to the midpoint P ₅ of P ₂ and P ₃ ing.

It is also possible to apply an appropriate correction coefficient to the curvature κ obtained by any of the above methods and use the result as the curvature.

Next, the passing speed determining unit 40 calculates the passing speed (feeding speed) F based on the curvature κ input from the curvature calculating unit 20 and the allowable acceleration a _{max of the} machine. Passing speed F
In calculating, for example, JP-A-63-106
The passing speed F is determined using the following equation (3) shown in Japanese Patent Publication No. 809. For example, as shown in FIG. 2 or 3, when the curvature is calculated by the sequence of four points P ₀ , P ₁ , P ₂ and P ₃ , the point P ₁ or the point P ₂ or the point P ₁ and the point P ₁ Determine the speed of passage in the interval between P ₂ and P ₂ .

F = k (a _max · R) ^1/2 (3) k is a proportional coefficient. R is the radius of curvature, R = 1 / κ
(Κ: curvature).

The passing speed determining unit 40 outputs the passing speed F thus obtained to the servo system controller (not shown) together with the trajectory data. In the servo system control device, at each position indicated by the trajectory data, acceleration / deceleration processing is performed for each axis so as to keep the input passing speed F, and the speed and sampling cycle Δt that have been subjected to the acceleration / deceleration processing per unit time After performing the interpolation process for calculating the movement amount of, the servo motors of 1 to a plurality of axes are driven.

Next, the features and effects of the curvature calculation method according to the first embodiment will be described. For example, as in the situation shown in the conventional example, as shown in FIG. 4A, 3 of the point sequences P ₀ , P ₁ , P ₂ , P ₃ , ... Consider a case where the _second point P ₂ deviates from the target locus due to an error due to CAM or the like.

In FIG. 4A, the second method described above is used.
It shows the case where the curvature is obtained by That is, the point P₀
To point P₁Vector V to₀Unit vector u of₀And point P₂
To point P₃Vector V to₁Unit vector u of₁Seeking
As the distance dl, the point P₀And P ₁From the middle point to P₂And P₃in
We use the length of the vector to the point. In FIG. 4 (b),
The two vectors u thus obtained₀, U₁And distance d
The arc (solid line) by the curvature obtained by l is the ideal
It shows how closely it matches the curvature of the trajectory (dashed line)
It As can be seen from FIG. 4 (b), the first two points P₀, P₁
Vector V connecting ₀Vector u₀And the latter half
2 points P₂, P₃Vector V connecting₁Vector that is a unit of
u₁Is almost equal to the tangential direction of the ideal arc.
The center of the arc ct₃Also matches the ideal arc center ct
To do. In this way, even if a point sequence error occurs,
It is possible to obtain a curvature close to an ideal arc.

Further, as shown in FIG. 5, the following four points P ₁ ,
When the radius of curvature is similarly calculated for the set of P ₂ , P ₃ , and P ₄ , the radius of curvature is slightly smaller than the radius of the ideal arc, but compared with the conventional technique, the arc center ct ₄ is the ideal arc center. It can be seen that it is close to the ct side and a sufficiently appropriate curvature can be obtained. That is, according to the method of the first embodiment, it is understood that the curvature that continuously changes is obtained as the section for which the curvature is calculated sequentially moves one by one.

As described above, in the first embodiment,
Since the command position data for four consecutive points is used and the curvature is obtained using the vector connecting the first two points of the four points and the vector connecting the second two points of the latter four points, The included error can be smoothed, an appropriate curvature can be calculated even if the distance between the point sequences is small, and further, a curvature that continuously changes over a wider range than in the past can be obtained. Therefore, the passage speed can be surely limited at the place where the passage speed should be limited without being influenced by the commanded interval of the point sequences and the placement error. Further, it is possible to determine the passing speed in the same manner even for the point sequences having different arrangements on the adjacent moving trajectories, and to change the passing speed continuously when the adjacent trajectories continuously change. It will be possible.

Embodiment 2. Next, a second embodiment of the present invention will be described. In the second embodiment, the point sequence buffer 30 shown in FIG. 1 holds the position data for a plurality of points (for example, eight points) larger than four points. The curvature is calculated by using the position data for the point.

That is, in the second embodiment,
A vector connecting the first point on the rear side of the point sequence section for which the current passing speed is to be determined and adjacent points in a plurality of point sequences existing after the first point is generated, and these vectors are further calculated. One vector is generated after the first point by recursively generating a vector that connects each of the points divided at a predetermined ratio between the adjacent points, and A vector connecting the second point and the adjacent points in the plurality of point sequences before the second point is generated, and each vector obtained by dividing the vector at a predetermined ratio is connected between the adjacent points. One second vector is generated before the second point by recursively generating the vector, and the curvature of the movement trajectory is calculated using the generated first and second vectors.

FIG. 6 shows four points P _{0 to} P _{3 on} the front side and four points P ₄ on the rear side of the section P _{3 to} P ₄ for which the current curvature is to be obtained.
₇ shows a curvature calculation method when using ~ P ₇ .

It is now assumed that the passing speed F in the section from the point P ₃ to P ₄ is determined. The point P ₀ of the line segment from the point P ₁ 1: q ₀ points is divided into 1, line 1 from the point P ₁ to point P _2: q ₁ points is divided into 1 point from the point P ₂ P the segment of the ₃ 1: 1 point q ₂ be divided into a point q ₀ a line from the point q ₁ 1: r ₀ that is divided into 1, a line segment from the point q ₁ to the point q ₂ 1: determined as r ₁ that is divided into 1, the vector from point r ₀ to the point r ₁ and V _0.

[0050] Further, the line segments similarly from the point P ₄ with respect to the point P ₇ from the point P ₄ to the point P ₅ 1: line 1 points is divided into q _3, from the point P ₅ to the point P ₆ The point q ₄ and the point P ₆ that divide the minute into 1: 1
A line from the point P ₇ 1: q ₅ points is divided into 1, line 1 from the point q ₃ to point q _4: r ₂ that is divided into 1, from the point q ₄ to point q ₅ The line segment is obtained as a point r ₃ dividing into 1: 1 and the vector from the point r ₂ to the point r ₃ is obtained as V ₁ .

Further, the line segment from the point r ₀ to the point r ₁ is 1: 1.
The distance between the point s that is divided into points and the point e that divides the line segment from the point r ₂ to the point r ₃ in a ratio of 1: 1 is obtained as dl. If these vectors V ₀ , V ₁ and the distance dl are given to the equation (2), the curvature κ can be calculated.

In the above, in order to estimate the curvature of a certain section, four points were used before and after the section, but the point sequence may have two or more points on each side. If two points are prepared on each side, a total of four points will be used, and if the division ratio is further set to 1: 1, the same result as the second method shown in the first embodiment can be obtained.

According to the second embodiment, as shown in FIG. 7, the arc having the curvature κ obtained from the two vectors V ₀ and V ₁ and the distance d ₁ is almost in the trajectory on which the point sequence is originally placed. Since they match, it can be seen that a reasonable curvature can be estimated.
Further, in the second embodiment, since the curvature is determined by referring to a larger number of point sequences than in the first embodiment, it is possible to perform the curvature estimation that is less susceptible to the error of the point sequence. In the second embodiment, the division ratio is preferably 1: 1,
Other ratios may be used.

Third Embodiment Next, a third embodiment of the present invention will be described. The applicant of the present invention is Japanese Patent Application 2000-
No. 64235 has already applied for a system for directly generating a servo command value from a curved surface model and a tool model used. In this application, an evaluation point is generated a predetermined amount ahead of the position at which the interpolation point is currently interpolated, and the next interpolation point is obtained using the parameter between the evaluation point and the evaluation point. An invention is shown in which a section is determined and an interpolation point is directly generated from a curved surface model and a tool model between two evaluation points.

In the system shown in this application, the passing speed is determined and determined using the evaluation points, but the interpolation points are not calculated on the straight line connecting the evaluation points at the time of interpolation, but the curved surface and the tool are used. Since the interpolation points are obtained directly from the model, when determining the passing speed, it is necessary to perform evaluation in anticipation of a sharp change in shape between evaluation points. Therefore, if the present invention is applied to a system for directly generating a servo command value from a curved surface model and a tool model used, which is disclosed in this Japanese Patent Application No. 2000-64235, a safe passage speed can be determined even during interpolation. It will be possible.

If the above method is programmed and executed by a computer, the program can be read by the computer, whereby the above method can be executed by the computer.

[0057]

As described above, according to the present invention, the curvature of the movement locus is calculated using the commanded position data for four or more consecutive points in the position data representing the tool locus, and the calculated curvature is calculated. Since the passing speed is controlled by using it, it is possible to smooth the error contained in the point sequence, calculate an appropriate curvature even if the distance between the point sequences is minute, and to continuously measure over a wider range than before. It is possible to obtain a curvature that changes to. Therefore, the passage speed can be surely limited at the place where the passage speed should be limited without being influenced by the commanded interval of the point sequences and the placement error. Further, it is possible to determine the passing speed in the same manner even for the point sequences having different arrangements on the adjacent moving trajectories, and to change the passing speed continuously when the adjacent trajectories continuously change. it can.

According to the next invention, since the curvature of the movement locus is calculated based on the vector connecting the first two points of the continuous four points and the vector connecting the second two points of the continuous four points, a small number of samplings are performed. With the number of points, it is possible to calculate an appropriate curvature even if the distance between the point sequences is small, and the curvature is strong against an error included in the point sequence.

According to the next invention, a plurality of point sequences are prepared before and after the line segment connecting the position data for which the current passing speed is to be determined and the position data immediately before l, and the respective point sequences are connected. Then, recursively generate a vector that connects the points created by dividing the vector with a predetermined ratio,
1 before and after finally trying to determine the current passing speed
Since the curvature is calculated using the vectors generated one by one, it becomes more difficult to be affected by the error in the point sequence. Therefore, the error contained in the point sequence can be smoothed, a proper curvature can be calculated even if the distance between the point sequences is small, and a curvature that continuously changes over a wider range than before can be obtained. . Therefore, the passage speed can be surely limited at the place where the passage speed should be limited without being influenced by the commanded interval of the point sequences and the placement error. Further, it is possible to determine the passing speed in the same manner even for the point sequences having different arrangements on the adjacent moving trajectories, and to change the passing speed continuously when the adjacent trajectories continuously change. become able to.

According to the next invention, the curvature of the movement trajectory is calculated using the commanded position data for four or more consecutive points in the position data representing the tool trajectory, and the passing speed is controlled using the calculated curvature. Therefore, it is possible to smooth the error contained in the point sequence, calculate a reasonable curvature even if the distance between the point sequences is small, and obtain a curvature that continuously changes over a wider range than before. Is possible. Therefore, the passage speed can be surely limited at the place where the passage speed should be limited without being influenced by the commanded interval of the point sequences and the placement error. Further, it is possible to determine the passing speed in the same manner even for the point sequences having different arrangements on the adjacent moving trajectories, and to change the passing speed continuously when the adjacent trajectories continuously change. it can.

According to the next invention, since the curvature of the movement locus is calculated based on the vector connecting the first two points of the continuous four points and the vector connecting the second two points of the four consecutive points, a small number of samplings are performed. With the number of points, it is possible to calculate an appropriate curvature even if the distance between the point sequences is small, and the curvature is strong against an error included in the point sequence.

According to the next invention, a plurality of point sequences are prepared before and after the line segment connecting the position data for which the passing speed is currently determined and the position data of the lth previous position data, and the respective point sequences are connected. Then, recursively generate a vector that connects the points created by dividing the vector with a predetermined ratio,
1 before and after finally trying to determine the current passing speed
Since the curvature is calculated using the vectors generated one by one, it becomes more difficult to be affected by the error in the point sequence. Therefore, the error contained in the point sequence can be smoothed, a proper curvature can be calculated even if the distance between the point sequences is small, and a curvature that continuously changes over a wider range than before can be obtained. . Therefore, the passage speed can be surely limited at the place where the passage speed should be limited without being influenced by the commanded interval of the point sequences and the placement error. Further, it is possible to determine the passing speed in the same way even for the point sequences having different arrangements on the adjacent movement trajectories, and to change the passing speed continuously when the adjacent trajectories continuously change. become able to.

According to the program of the next invention,
Since the computer is made to execute the method described in any one of the above-mentioned inventions, the program becomes computer-readable, whereby the operation of any one of the above-mentioned inventions can be executed by the computer. It has the effect of being able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a speed control device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing point sequence data and vectors for explaining a curvature calculation method according to the first method of the first embodiment.

FIG. 3 is a diagram showing point sequence data and vectors for explaining a curvature calculation method according to a first method of the second embodiment.

FIG. 4 is a diagram for explaining a comparison between an arc obtained by the first embodiment and an ideal arc.

FIG. 5 is a diagram for explaining a comparison between an arc obtained by the first embodiment and an ideal arc.

FIG. 6 is a diagram showing point sequence data and vectors for explaining a curvature calculation method according to the first method of the second embodiment.

FIG. 7 is a diagram for explaining a comparison between an arc obtained by the second embodiment and an ideal arc.

FIG. 8 is a diagram showing adjacent movement loci.

FIG. 9 is a diagram for explaining a defect of the conventional technique.

[Explanation of symbols]

10 point sequence output section, 20 curvature calculation section, 30 point sequence buffer, 40 passing speed determination section.

Claims (7)

[Claims] 1. A curvature calculation unit that calculates the curvature of the tool path using command position data of each point of a point sequence indicating the tool path, and a passage that calculates a passing speed based on the calculated curvature and the allowable acceleration of the machine. A velocity determining unit, wherein the curvature calculating unit calculates the curvature of the movement trajectory by using command position data regarding four or more consecutive points in the position data representing the tool trajectory. 2. The curvature calculation unit calculates the curvature of a movement locus based on a vector connecting two points in the first half and a vector connecting two points in the second half, using command position data of four consecutive points. The speed control device according to claim 1. 3. A curvature calculation unit for calculating the curvature of the tool path by using command position data of each point of a point sequence indicating the tool path, and a passage for calculating a passage speed based on the calculated curvature and the allowable acceleration of the machine. A velocity determination unit, wherein the curvature calculation unit is configured such that the curvature calculation unit includes a first point on the rear side of the point sequence section which is currently determining the passing velocity and adjacent points in a plurality of point sequences existing after the first point. To generate a vector connecting the points and dividing each of the vectors at a predetermined ratio to recursively generate a vector connecting the adjacent points to each other to generate one vector after the first point. A vector is generated, and a vector connecting the second point on the front side of the point sequence section and adjacent points in a plurality of point sequences before the second point is generated, and these vectors are further set to a predetermined ratio. Each point divided by 1 before the second point by recursively generate vector connecting between the point
A second speed vector is generated, and the curvature of the movement trajectory is calculated using the generated first and second vectors. 4. A first step of calculating the curvature of the tool path by using command position data of each point of a point sequence indicating the tool path, and a passing speed is calculated based on the calculated curvature and the allowable acceleration of the machine. A second step, wherein in the first step, the curvature of the movement locus is calculated using command position data for four or more consecutive points in the position data representing the tool locus. Method. 5. In the first step, the command position data of four consecutive points is used, and the curvature of the movement trajectory is calculated based on the vector connecting the two points in the first half and the vector connecting the two points in the latter half. The speed control device according to claim 4, which is characterized in that. 6. A first step of calculating a curvature of a tool path using command position data of each point of a point sequence indicating a tool path, and a passing speed is calculated based on the calculated curvature and an allowable acceleration of a machine. A second step, wherein in the first step, the first point on the rear side of the point sequence section for which the passing speed is currently determined and the adjacent points in the plurality of point sequences existing after the first point are adjacent to each other. To generate a vector that connects the points, and recursively generate a vector that connects each of the points obtained by dividing the vector at a predetermined ratio between the adjacent points to generate one vector after the first point. 1 is generated, a vector connecting the second point on the front side of the point sequence section and adjacent points in a plurality of point sequences before the second point is generated, and these vectors are set to a predetermined value. Each divided by the ratio of The generated one second vector before the vector connecting between adjacent points the second point by generating recursively generated first
And a velocity control method, characterized in that the curvature of the movement trajectory is calculated using the second vector. 7. A program for causing a computer to execute the method according to any one of claims 4 to 6.