JP2728987B2 - Mobile body movement control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movement control apparatus for a moving body such as a measuring element of a coordinate measuring machine or a robot arm, and more particularly, to numerical data of a target point and a halfway point from a current point given from a host computer. The present invention relates to a movement control device that controls a moving body.

[0002]

2. Description of the Related Art In a three-dimensional measuring system, movement of a probe is controlled, for example, by a part program of a host computer. The movement command data given from the host computer is usually data indicating three-dimensional coordinate values of a target point to be moved and a halfway passing point. The data on the way point is given to prevent interference between the workpiece and the probe. Controller for CNC CMM (Coordinate Measuring Macine Cont)
When the movement commands sent from the host computer are continuous, the roller controls the movement of the probe by performing positioning for each command.

[0003]

However, with such a control method, the moving direction of the probe changes at the midway passing point, so that the probe is decelerated to zero speed before and after passing the midway passing point. The process of accelerating again is always performed. For this reason, there is a problem that a time loss occurs due to the acceleration / deceleration processing, and the measurement time becomes longer. Such a problem occurs not only in the CNC coordinate measuring machine but also in CNC machine tools and robots.

[0004] It is an object of the present invention to provide a movement control apparatus for a moving body capable of shortening the moving path and moving time of the moving body without changing the form of the movement command. .

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a movement control apparatus for a moving body, which interprets a movement command including a coordinate value of a target point and a coordinate value of a passing point on the way to the target point. Means, and a movement command decomposing means for decomposing a movement command specifying a path from the current point of the moving body to a halfway point and a path from the halfway point to the target point based on the interpretation result of the movement command, An arc path interpolation command for smoothly connecting the path following the current point and the path following the target point to the path following the current point and the path following the target point out of the movement commands decomposed by this means. A moving control device for a moving body, comprising:
Wherein the movement command interpreting means is a host computer.
To move to the next halfway point sequentially transmitted from
Command is read and interpreted sequentially.
Moving command disassembly means,
From the current point of the moving object,
When the distance to the middle passing point is more than the predetermined distance
As long as the movement command is decomposed and the arc path interpolation
Command generation means determines that the current point of the moving object is a movement command.
Movement without reaching the predetermined range before the decomposition point
Command interpretation means pre-reads and interprets the next movement command
Two consecutive, look-ahead and interpreted only if
The radius of curvature of the arc-shaped path is adjusted based on the movement command of
Processing by the arc path interpolation command while adjusting
Is performed .

[0006]

According to the present invention, when a movement command is given, the movement command interpreting means interprets it by, for example, pre-reading it, and the movement command decomposing means interprets the path from the current point to the intermediate passing point designated by the movement command. Each route from the passing point to the target point is decomposed. Then, the arc-shaped path interpolation command generation means generates an arc-shaped path interpolation command such that the moving body smoothly moves along both paths in an arc shape (for example, a two-dimensional or three-dimensional circular arc or a parabolic shape).

Therefore, according to the present invention, since the moving distance of the moving body can be reduced and the acceleration and deceleration of the moving body can be suppressed, the moving time to the target position can be made longer than before. And the working time can be shortened. Moreover, according to the present invention, the movement command itself given from the host computer does not need to be changed at all from the prior art, so that there is no need to change the control program on the host.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of a three-dimensional measurement system according to one embodiment of the present invention. This system comprises a host computer 1, a controller 2 and a CN.
And a C coordinate measuring machine 3. The host computer 1 outputs a probe movement command according to, for example, a part program. The controller 2 interprets and executes a movement command given from the host computer 1, and drives and controls an X-axis motor 17, a Y-axis motor 18, and a Z-axis motor 19 for driving a probe of the coordinate measuring machine 3. Control processing unit 11, system management unit 12,
It comprises a pre-movement processing unit 13, a movement interpolation processing unit 14, and a digital servo processing unit 15.

FIG. 2 is a block diagram showing functions of the controller 2. The movement command buffer 21 receives a movement command supplied from the host computer 1, and the communication control processing unit 11 in FIG. 1 manages this function.

The movement command pre-reading / interpreting unit 22 pre-reads and interprets the moving command buffered in the moving command buffer 21, and supplies only the moving command that meets various conditions such as the moving distance to the moving command decomposing unit 23. The movement command disassembly unit 23 disassembles the movement command, notifies the automatic radius adjustment unit 24 when the next movement command can be read ahead, and determines that the circular interpolation cannot be performed when the movement command cannot be read ahead. This is transmitted to the movement command generation unit 25. Movement command generator 25
Generates an execution command by performing the same processing as before when circular interpolation is not possible. The automatic radius adjuster 24 automatically adjusts the radius of the circular arc portion even when circular interpolation is possible but the moving path becomes an acute angle or the moving distance is short. The circular interpolation command generation unit 26 generates an execution linear part and a circular part movement command when circular interpolation is possible. These units 22 to 26 are executed by the system management unit 12 and the pre-movement processing unit 13 in FIG.

The execution movement command buffer 27 is shown in FIG.
Buffering the execution movement command generated by the movement command generation unit 25 and the circular interpolation command generation unit 26. The movement command execution unit 28 includes a command buffer 27
The digital servo processor 15 shown in FIG. 1 is responsible for controlling the drive of the coordinate measuring machine 3 by executing the execution movement command buffered in FIG.

Next, the operation of the controller 2 will be described. FIG. 3 is a flowchart showing the operation of the controller 2, and FIGS. 4 and 5 are diagrams for explaining a specific example of the arc interpolation processing. In this system, movement commands are sequentially output from the host computer 1 , and these movement commands are output.
Probe in real time while analyzing motion commands sequentially
This is characterized in that the movement control is performed.

The initial value of the radius R of the circular arc orbit may be appropriately determined according to the radius of the probe tip ball 31 and the distance between the probe tip ball 31 and the work 32, as shown in FIG. For example, if the radius of the probe tip ball 31 is 1 mm and the distance between the probe 31 and the work 32 is 2 mm,
The radius R at which the probe tip ball 31 does not contact the workpiece 32 can be set to about 3 mm.

The movement commands sequentially output from the host computer 1 are sequentially stored in the movement command buffer 21, and are pre-read and interpreted by the movement command pre-reading / interpreting unit 22 (S1). Now, as shown in FIG. 5, assuming that the current point of the probe tip ball 31 is P0, and a passing point P1 is given as the movement command C1, first, P
The distance L from 0 to P1 is calculated, and if this L is smaller than R, the circular interpolation with the radius R is impossible, so that R
= L / 2 and the processing is continued (S2, S3).

Next, it is determined whether or not the distance L specified by the movement command C1 is a distance at which the automatic circular interpolation process can be sufficiently performed (S4). That is, a probe radius of 1 mm is the minimum radius value Rmin that can be used for circular interpolation, the maximum command movement speed at that time is V, and after the controller 2 receives a movement command from the host computer 1, the command is interpreted and an automatic arc is interpreted. Assuming that the time until the output of the interpolation control command is t and the safety factor is α (α ≧ 1), the following Expression 1 may be determined.

[0016]

L ≧ Rmin + R + V (t × α)

It is difficult to strictly specify the value of t in an actual system, and a value having a margin is set for the safety factor α. If the distance L does not satisfy the condition of Equation 1, there is no time margin for the circular interpolation processing, so that the circular interpolation processing is not performed, and the conventional movement command generation processing based on the positioning factor (positioning width) is executed. Yes (S1
0). When the distance L satisfies the condition of Equation 1, the movement command C1 (P0 to P1) is changed to the movement command C11 (P0 to P1).
PA) and C12 (PA to P1) (S5). PA
Is the position before P1. That is, the movement command C1
Is issued, the position of P2 is still unknown, so the process proceeds assuming that the movement command C2 is a command to move at right angles to C1. Before the current movement position enters the range of V (t + α) before PA, the next command C2 (P1 to
Only when P2) is received, the arc command C1 '(P
A to PB) and a straight line command C21 (PB to PC) are generated and automatically circularly interpolated (S9). If the reception of the next movement command from the host computer 1 is delayed, or if the movement command indicates movement on the same straight line,
In each case, no circular interpolation is performed, and the probe ball 31 moves to P1 (S6, S10).

Even if circular interpolation is possible, for example, P
If the movement path is sharp, such as at two points, or if the movement distance is short, to prevent interference with the workpiece,
Automatic radius adjustment is performed (S7). When the radius R 'becomes smaller than the probe radius 1 mm as a result of the radius adjustment,
The conventional movement command generation processing is executed without performing the circular interpolation (S8, S10). If not, an arc interpolation process is executed (S9). By repeating the above processing, it is possible to shorten the moving time by shortening the moving path of the probe and suppressing acceleration / deceleration.

According to the present system, as shown in FIG.
P0 is the current point, P1 is the waypoint, P2 is the target point,
Assuming that P0 to P1 and P1 to P2 are orthogonal to each other, the arc trajectories PA to PB are linear trajectories (PA to P1 + P1 to P1).
B) is 0.785 times, so the travel distance in this part is 0.
215 (PA〜P1 + P1〜PB).

FIG. 7 is a diagram showing a comparison between the speed patterns when the circular interpolation is not performed (a) and when the circular interpolation is performed (b) in the moving process of FIG. That is, in the conventional method shown in FIG. 2A, it is necessary to temporarily reduce the speed at the intermediate passing point P1 from the current point P0 to the target point P2 via the intermediate passing point P1. For this reason, it takes time to accelerate and decelerate when moving the probe. On the other hand, in this method, the arc trajectories PA,
In the portion of PB, the speed may be reduced slightly more than in the linear portions P0 to PA and PB to P2, and there is no need to stop, so that the moving time of the probe can be shortened accordingly.

The present invention is not limited to the above embodiment. For example, positioning control based on a positioning factor may be performed based on a control response characteristic at a joint between a straight line and an arc and a joint between an arc and a straight line. If an error occurs due to the probe touching the workpiece in the arc due to an inappropriate arc radius or the like, switching to coordinate value control is automatically performed at that point, and the movement process may be continued. Good. It is known that a radius deviation (shrinkage) occurs during movement on an arc trajectory. However, control may be performed in advance by adding a correction amount to an arc command. In addition, since the moving speed that can be achieved in the arc portion is different from that of the straight portion when viewed from the acceleration resistance of the machine, the acceleration / deceleration processing adapted to the control target machine is also performed for the straight portion to the arc portion and the arc portion to the straight portion. It is desirable.

Further, it goes without saying that the present invention can be applied not only to the probe of the coordinate measuring machine but also to the movement control of a robot arm or the like.

[0023]

As described above, according to the present invention, the moving distance of the moving body can be reduced, and the acceleration and deceleration of the moving body can be suppressed. Can be greatly reduced as compared with the related art, and the working time can be reduced. Moreover, according to the present invention,
Since the movement command itself given from the host computer does not need to be changed at all, there is no need to change the control program on the host.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a CNC three-dimensional measurement system according to one embodiment of the present invention.

FIG. 2 is a functional block diagram of a controller in the system.

FIG. 3 is a flowchart showing the operation of the controller.

FIG. 4 is a diagram illustrating a relationship between a radius of an arc trajectory, a probe ball, and a workpiece.

FIG. 5 is a diagram illustrating an example of a movement path of a probe.

FIG. 6 is a diagram for explaining a reduction amount of a moving distance of a probe.

FIG. 7 is a diagram illustrating a relationship between a moving time and a moving speed of a probe in the same system as compared with a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Host computer, 2 ... Controller, 3 ... Coordinate measuring machine, 11 ... Communication control processing part, 12 ... System management part, 13 ... Pre-movement processing part, 14 ... Movement interpolation processing part, 15
... Digital servo processing unit, 21 ... Move command buffer, 22 ... Move command pre-reading / interpretation unit, 23 ... Move command decomposition unit, 24 ... Automatic radius adjustment unit, 25 ... Move command generation unit, 26 ... Circular interpolation command generation unit, 27: Move command buffer for execution, 28: Move command execution unit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Noda 165 Sakado, Takatsu-ku, Kawasaki, Kanagawa Prefecture, Ltd. Mitutoyo System Technology Development Room (72) Inventor Tomoki Tsuruta 165 Sakado, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Mitutoyo System Technology Development Room Co., Ltd. (56) References JP-A-1-84309 (JP, A) JP-A-1- 201719 (JP, A)

Claims (2)

(57) [Claims] 1. A coordinate value of a target point and a way to reach the target point.
Interpret the movement command including the coordinates value of the middle passing point
Command interpreting means, and the
And the route from the current point of the mobile
A moving frame that specifies the route from the passing point to the target point
Moving command decomposing means for decomposing commands respectively, and this means
Of the movement commands decomposed in
A movement command specifying a route including
And the path following the target point are connected smoothly and arcuately.
Path interpolation command to be replaced with an arc path interpolation command
Command generation meansIn the movement control device of the moving body
hand, The movement command interpreting means is provided by a host computer.
A movement command to move to the next waypoint that is transmitted sequentially
Read and interpret the command sequentially, The movement command disassembly means is a means for interpreting the movement command.
Based on the result of the interpretation at the step,
If the distance to the passing point is more than a predetermined distance
Disassembly the move command only if The arc-shaped path interpolation command generation means is configured to generate a current
When the present point reaches a predetermined range before the decomposition point of the movement command
The movement command interpreting means
Read-ahead and interpretation only if the
The arc based on two consecutive moved commands
The arc path interpolation command while adjusting the radius of curvature of the arc path.
Execute the replacement process by using Is the thing Features
A moving control device for a moving object. 2. An arc route interpolation command generation means, comprising:
2. The movement control device for a moving body according to claim 1, wherein a radius of curvature of the arc-shaped path is adjusted according to an angle formed by a movement path from a current point to a target point through a midway passing point. .