JPH07109562B2 - Robot path tracking controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for aligning a robot with a target path in a space, and in particular, the target path is sequentially corrected according to the detected position information so that the robot can accurately measure the target path. The present invention relates to a control device suitable for following.

[Background of the Invention]

Conventionally, the robot path follow-up control is such that a target path that is numerically given or taught beforehand is corrected using a signal obtained from a detection device, and that the path is stored in the robot in advance. In some cases, only the signal obtained from the detection device and the information on the current position are used.

Many of the detection devices used in these tracing controls detect the distance between the current position of the predetermined portion of the robot and the target path such as the surface of the work object or the attitude error of the robot. Some of them are installed in front and are used for predictive control with good responsiveness by detecting a target position. An apparatus for detecting the target position and performing the path tracing control is described in Japanese Patent Publication No. 56-27348. This is a device in which a plurality of welding torches follow the welding line detected by the detector. This device makes the signal of the target position follow mechanically without delay,
It has the drawback that it cannot follow a curve and is not suitable for tracing the inner surface of the work object unlike the articulated robot because it is a rectangular coordinate type large device.

On the other hand, as a method of updating the detected stored target position, a method of updating on the condition that the distance between the current position and a certain point is below a certain value, or a certain distance from the certain point having the current position Although methods such as updating on the condition that they are separated from each other have been proposed, all of them are vulnerable to disturbance, and if the former method does not sufficiently approach a certain point once, the target position will not be updated thereafter. The robot may run out of control. Even with the latter method, there is a problem in that once the robot deviates from the path, the target position is updated one after another and the robot may run out of control.

[Object of the Invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device that uses a target position to adapt a robot to a target path and accurately follow the target path.

[Outline of Invention]

In order to achieve the above-mentioned object, the present invention stores a plurality of target positions detected by a detection device and updates the path generated based on the currently used target position as a condition for updating to the next path. , Monitoring the point where the distance between the robot's current position and the next target position turns from decreasing to increasing, judging that the operating point of the robot has reached the target position,
It is a modification of the robot movement path.

With this configuration, the robot can be surely made to follow the target path.

Example of Invention

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an external view showing a robot and a control device of the present invention. In FIG. 1, a robot 1 and a robot controller 2
And the teaching operation panel 3 is connected by a cable. A detection device 5 is installed in the vicinity of the end effector 4 of the robot 1, and the detection device 5 is rotated around the end effector 4 by a motor 6. The signal generated by the detection device 5 is processed by the signal processing device 7 and converted into the position of the robot coordinates. The robot control device 2 described above stores the deviation amount between the means for sequentially storing the plurality of target positions detected by the detection device 5 in time series, the means for storing the teaching path, and the present position of the robot or the teaching path. And a means for correcting and updating the robot position by monitoring and determining that the operating point of the robot has reached the target position when the deviation amount starts to decrease and increases.

Next, how the control device of the present invention causes the robot to follow the target path will be described with reference to FIG. In this figure, 8 is a taught path, 9 is an actual target path, and 10 is one of future target positions A _n detected by the detection device 5. Reference numeral 11 is originally a path correction amount based on the target position A _n-1 .
Similarly, 12 and 13 are correction amounts based on A _n and A _{n + 1} . Each 14, 15 and _{16 A n-1, A n} , curve l _n-1 gives a command position with modifications based on the A _{n + 1,} l _n, a l _{n + 1.}

The correction amount 12 based on the future target value 10 forms a vector orthogonal to the taught path 8, and the curve connecting the vector end points is the curve 15 giving the command position.

Next, the operation of updating the future target position and switching the curve giving the command position will be described with reference to FIG. A continuous future target position 10 with an error is given to the taught path 8. The current position 17 of the end-if ecta follows the command curve l _n-1 14 based on the current n-1th future target position. The distance between the current position 17 of the end-if ecta and the nth future target position 10 is monitored, and the end-if ecta is based on the n-th future target position on condition that the distance has changed from decreasing to increasing. Switch to follow the command curve l _n 15.

A method for storing and updating the future target position processed by the control device 2 in the embodiment of the present invention will be described with reference to FIGS.
And shown in the flow chart of FIG.

According to the embodiment of the present invention, the correction amount 1 applied to the teaching path 8
There is an effect that it is possible to reliably update 1,12,13 by a method that is strong against disturbance.

〔The invention's effect〕

As described above, according to the present invention, even after the target position is detected, for example, even when the object to be copied moves with respect to the path, it is possible to update the previously taught path and accurately cause the robot to follow the target path. The effect that it becomes possible is obtained.

[Brief description of drawings]

FIG. 1 is an external view showing a robot and a path tracing control device according to an embodiment of the present invention, FIG. 2 is a principle view showing how the robot follows a target path, and FIG. A principle diagram showing a method for switching a curve giving a command position, FIGS. 4 and 5 are a series of flow charts showing algorithm in the robot controller of the present invention, and FIG. 6 is a signal processing constituting the device of the present invention. It is a flow chart which shows an algorithm in a device. 1 ... Robot, 2 ... Robot control device, 4 ... End effector, 5 ... Detection device, 7 ... Signal processing device,
8 …… Teached path, 9 …… Actual target path, 10 ……
Future target position, 11,12,13 …… Path correction amount, 14,15,16 ……
Curve that gives the command position, 17 …… Current position of End If Equator.

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Claims (1)

[Claims] 1. A first memory for sequentially storing target positions detected in time series by the detector in a path control of an end effector of a robot to a target position detected by a detector in advance. Means, second storage means for storing a teaching path taught in advance in time series, first computing means for computing the position of the end effector when moving in the target position direction, and the first The distance between the position of the end effector obtained by the calculation means and the target position stored in the first storage means is monitored, and when the value of this distance increases from a decrease, the end effector reaches the target position. And a second calculation means for outputting to the robot a correction command in which a correction amount is added to the teaching path stored in the second storage means. Path tracing control device.