JPH0199104A - Profile control system - Google Patents

Abstract

PURPOSE:To attain the profile control with a high accuracy even when an off-set exists between a position controlled system and a position detector by equipping with a detecting time difference compensating device to compensate the time difference between a position detection and a target position calculation. CONSTITUTION:Between a detecting position memory 3 and a target position control device 6, a detecting time difference compensating device 17 to delay only the time needed when a robot 8 moves the clearance of a tip part 10 of an end effector and the scanning position of a position detecting device 1 is added. Even when the position detector 1 operates the position to precede at a constant distance only for the tip part 10 of the end effector and the tip part 10 arrives at the scanning point of the position detection, the target position is determined based on the detection position at the scanning point and thus, the tip part 10 of the end effector can be made coincident to the actual welding line. Thus, the error accompanying the off-setting between a position controlled system and a position detector can be compensated and simultaneously, the profile operation with a high accuracy can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a tracing control system suitable for performing tracing processing such as welding and machining by, for example, a robot or an automatic machine tool.

[Prior Art] Fig. 5 shows the installation state of the main elements of this type of conventional scanning control system, and shows the mounting state of the main elements of this type of conventional scanning control system.
An end effector (9) is attached to the tip of the end effector (9), and a position detector (9) is attached to the end effector (9).
1) is installed.

Fig. 6 shows the state in which copy welding is performed using this copy control system, and the position detector (1 ) is installed. It is equipped with a light emitter (12) and a light receiver (13), and has a welding line (11).
) to detect the position from the tip (lO) of the end effector.

FIG. 4 is a block diagram showing the configuration of a control main body that operates the robot (8) based on position data detected by the above-mentioned position detector (1) (hereinafter, position data is also referred to as vehicle position). be. In the same figure, (2) is the position detector (1
) converts the position in the operating unit coordinate system detected by the controller into the position in the absolute coordinate system of the tracing control system;
) is a detection position memory that stores the converted absolute coordinate system position data, and (4) is the tip of the end effector (
(10) is a taught position memory that stores a so-called taught position in which an approximate 8-shift route is specified; (5) is a taught position manager that reproduces a taught target position while interpolating the taught position;
6) is the reproduced teaching target position and the detected position memory (3).
) is a target position manager that determines the target position by combining the detection positions of the end effector and the detected position, and (7) is an output converter that converts into a signal to move the tip (10) of the end effector to the determined target position.

Next, the operation of this scanning control system will be explained below with reference to the operation explanatory diagram of FIG. 7.

The target position controller (6) displays the actual welding line (
11) and gives a position detection command to the position detector (1) via the position converter (2). Position detector (
1) emits a light beam from a light projecting section (12), receives reflected light from the surface of the welding material at a light receiving section (13), and measures the distance. At the same time, the position detector (1) is operated as shown by the broken line in Fig. 6 to obtain a distance pattern to the material surface, and then this distance pattern is analyzed to determine the weld line (11) as the object to be traced. Determine the position of the operating unit coordinate system. The position converter (2) converts the position of the operating unit coordinate system to the position of the robot's absolute coordinate system, and writes the detected position memo 'J - (
3) are stored sequentially.

In addition, the teaching position management device (5) has a teaching position memory (4).
The taught target position is calculated by interpolating the taught position. In parallel with this, the detected position of the detected position memory (3) is read out. The target position manager (6) combines the taught target position and the detected position to determine the final target position. The output converter (7) converts the signal to move the tip (10) of the end effector (9) to this target position, and supplies the signal to the robot (8) to move it.

After moving a certain amount, the robot (8) moves to a new target position based on the next detected position of the position detector (1).
move. Thereafter, welding along the groove (11) is performed by repeating the same operation.

[Problem that the invention seeks to solve]

In the conventional tracing control system described above, the position detector (1) operates at a position that is a certain distance ahead of the welding torch (10) as the position control target. There is a problem in that the accuracy of copying decreases due to the presence of so-called offset.

FIG. 7 is an explanatory diagram for explaining this, in which the tip (10) of the end effector is connected to the actual welding line (11).
In order to follow this, the detection position of the position detector (1) is
At this time, the tip (10) is the tracing starting point P.

Suppose there is. Next, if the tip (10) moves and the detected position of the position detector (1) becomes 51% S2, the change is small, so the position C of the tip (10)
I and C2 also do not change that much, and the tracing starting point P1
It no longer follows the actual welding line (11) which is curved. This may indicate the situation in a part of the actual weld line (11) with a large curvature, or the same situation may occur in a part where the direction of curvature is reversed, which may reduce the accuracy of tracing. It ends up.

This invention was made to solve the above problems, and aims to provide a tracing control system that enables highly accurate tracing control even when there is an offset between the position control target and the position detector. purpose.

[Means for solving problems]

In the tracing control system according to the present invention, the detection position that is combined with the taught target position in order to obtain the target position of the position control object is set at a distance corresponding to the distance between the position control object and the position scanned by the position detector by the operating body. The device is equipped with a detection time difference compensator that sequentially delays the signal by the time required to move the signal and sends out the signal.

[Effect]

In this invention, by transmitting the detected position with a delay, the target position is calculated when the position controlled object reaches the detected position. It is possible to compensate for errors and at the same time to perform highly accurate copying operations.

(Embodiment) FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 4 indicate the same elements. Then, between the detection position memory (3) and the target position management device (6), the robot (8) determines the distance between the tip (10) of the end effector and the scanning position of the position detector (1). The configuration includes a new detection time difference compensator (17) that delays the time required for movement.

Next, the operation of this embodiment will be explained with reference to the operation locus of FIG. 2 and according to the flowchart of FIG. 3.

As mentioned above, the target position management device (6) is located at the welding line (11).
), and send a position detection command to the position detector (1) via the position converter (2), the position detector (1)
emits light, receives light, and scans to obtain a distance pattern on the surface of the welding material, analyzes this, and detects the position of the welding line (11) (step 31).

Next, the position converter (2) converts the detected position in the operating unit coordinate system to a position in the robot absolute coordinate system, and stores it in the detected position memory (3) as the detected position Sn (step 32).
.

Then, detecting positions 51 to 5 which have already been stored in the same manner.
The detection position located on the advancing direction side of the tip (10) in N-2 and closest to this tip (10), for example, Sl, is near the tip (10), that is, within the range of constant pressure 1iIL. The detection time difference compensator (17) determines whether the
-If the pressure is within 11L for running, repeat the position detection and storage, and if it is within the constant pressure liL, execute target position calculation (
Step 33).

This target position calculation outputs the detected position S1 close to the control position, moves the pointer eight times to the position S2, and newly sets S2 to Sn to 51 to 5n-1 (step 34).

In parallel with this, the interpolated teaching position is output from the teaching position management device (5) (step 35).

Next, the target position management device (6) adds a vector to the detected position S2 and the interpolated taught target position to obtain a target position (step 36).

In addition, the target position management device (6) indicates that the target position is the tracing end point P.
It is determined whether or not it exceeds n. If it does, the operation ends; if it does not, the process from the position detection operation is repeated (step 37).

Thus, according to this embodiment, even if the position detector (1) operates at a position that is a certain distance ahead of the tip (10) of the end effector, the tip (10) remains at the scanning point for position detection. When the target position is reached, the target position is determined based on the detected position at this scanning point.As a result, even if the actual weld line has a large curvature or there are parts with different curvature directions, , as shown in FIG. 2, the tip (10) of the end effector can be aligned with the actual weld line.

In addition, although the said Example demonstrated the case where it applied to a welding robot, this invention is not limited to this, For example, it can apply also to an NO sub-control machine tool.

〔Effect of the invention〕

As is clear from the above description, since the present invention includes a detection time difference compensator that compensates for the time difference between position detection and target position calculation, there is an offset between the position control target and the position detector. This has the effect of enabling highly accurate tracing control even in the case of

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
Fig. 2 is a tracing trajectory diagram for explaining the operation of the same embodiment;
Fig. 3 is a flowchart for explaining the operation of the same embodiment, Fig. 4 is a block diagram showing the configuration of the control section of the conventional scanning control system, and Fig. 5 is a perspective view showing the installation state of the main elements of the system. 6 is a perspective view showing the detailed configuration of the position detecting section of the system, and FIG. 7 is a tracing trajectory diagram for explaining the operation of the system. (1): Position detector (2): Position converter (3)
:Detection position memory (4):Teaching position memory (5)
: Teaching position management device (6) Two target position management device (7):
Output converter (8): Robot In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A position control target is attached to the operating body, and a position detector is attached to scan a position preceding the position control target to detect the position of the scanning target, and the detection position data detected by the position detector is converted into absolute coordinates. At the same time, the taught position data of the object to be scanned is stored in the taught position memory, and the taught target position data obtained from this taught position data and the taught position data are stored in the detected position memory. In a copying control system that obtains target position data of the position control object by combining it with stored detected position data, the detected position data of the detected position memory that is combined with the taught target position data is combined with the position control object. A tracing control system comprising a detection time difference compensator that sequentially delays the time required for the operating body to move by the distance between the operating position and the operating position of the position detector.