JPH0728520A - Origin return control method for robot - Google Patents

Abstract

PURPOSE:To provide the origin return control method for a robot which can surely return the robot to the origin with a simple constitution while suppressing the interference very much, namely, without collision with another jig or the like at the time of returning the robot, which has plural kinds of movement commands and can take various routes at the time of work, to the origin. CONSTITUTION:When an already executed control command is successively reversely executed, the position from which the robot is started by a movement command at the time of normal operation (continuous line) is replaced with the arrival position for return operation, and the position argument of the just preceding movement command is used to execute each movement command, and thereby, the robot is moved back along the route (continuous line) for normal operation and is returned to the work origin (broken line). Or one or plural preliminarily determined movement commands are skipped to short-circuit a part of the route and the robot is returned to the work origin when the already executed control program is successively reversely executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot control method, and more particularly to a control method for returning a robot stopped in the middle of a normal work program to a work origin.

[0002]

2. Description of the Related Art In recent years, multi-axis robots have been widely used for assembling automobiles. Immediately after turning on the power, or when restarting a robot that stopped during assembly for some reason, the movable part of the robot returns to its mechanical or electrical initial position (origin position) to prevent robot runaway. I have to let them do it.

Therefore, it is considered that the robot controller has a function of returning to the work origin, and the work program of the robot is executed in reverse to return the robot to the work origin.

FIG. 16 shows an example of a robot work program, which includes "MOVE", "MOVES",
The control command group is composed of a set of commands such as “SWITCH” and arguments such as P [1] and P [2]. Here, “MOVE” is a command that specifies only the points to be moved, and the path to be moved between the points is determined by an appropriate axis operation. “MOVES” is a linear operation command that moves the robot tip in a straight line. I mean.
"SWITCH" is a signal output command,
“WAIT” is a signal input waiting command. Of course, as the robot work program, it is possible to execute the same operation by using another command. In a normal operation, this work program is interpreted by an interpreter in the robot controller and sequentially executed from top to bottom in FIG. When the robot stops during the execution of such a work program, the interpreter in the robot controller executes the work program in reverse. That is, in FIG. 16, a work program which is normally executed from top to bottom is reversely executed from bottom to top.

On the other hand, instead of sequentially executing the work programs in reverse, a dedicated program for returning the work origin is prepared in advance, and the robot can be returned to the work origin by activating the dedicated program. It has been proposed (for example, JP 60-156104 A).

Although not a method of returning to the work origin, as a similar technique, a technique of reading trajectory data at the time of work in reverse order and returning to a desired position when a return command is generated (for example, a special technique) Kaihei 2-76691) is also proposed.

[0007]

However, if the interpreter in the robot controller simply executes the work programs in reverse, in the case of work programs that have different movement commands and thus can take different paths,
There is a problem that it is not possible to return to the origin by following the same route as during normal work.

FIG. 17 shows a robot path (solid line in the figure) when working according to the work program shown in FIG. 16 and a robot path (dashed line in the figure) when the work program is simply executed in reverse. It is shown. As described above, the work program shown in FIG. 16 includes “MOVE” and “M”.
Since there are two types of movement commands "OVES", the two routes do not match if they are simply executed in reverse. The route that was moved by "MOVE" during normal work is moved by "MOVES" at the time of returning, and is moved by "MOVE" during normal work.
This is because the route moved by "S" will be moved by "MOVE" when returning. When a multi-axis robot is used, the space of its movement path is often limited due to the relationship with other robots and tools. Therefore, when following a path different from normal work when returning to the origin in this way. Has a problem of colliding with other jigs (hereinafter referred to as interference).

On the other hand, in a configuration such as that disclosed in Japanese Patent Laid-Open No. 60-156104, in which a dedicated program for returning to the origin is provided, even if the robot is stopped at an arbitrary position in advance, it will not interfere with peripheral devices such as jigs. Since it is necessary to confirm that the program returns, it is necessary to confirm the operation of the program for returning in addition to the original work program, and there is a problem that the procedure becomes complicated.

Further, as in Japanese Patent Laid-Open No. 2-76669, a structure is used in which, when a return command is issued, the orbital data at the time of work is read in the reverse order and the work is returned to a desired position. If this is done, the capacity of the buffer memory for storing the orbital data will increase significantly, which is not practical.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to easily return a robot having a plurality of different types of movement commands and capable of taking different routes during work to the origin. Configuration, and
An object of the present invention is to provide a method for returning to the origin of a robot, in which the coherence can be suppressed to a very small value, that is, the origin can be surely returned without colliding with another jig or the like.

[0012]

In order to achieve the above-mentioned object, a method of returning to origin of a robot according to a first aspect of the present invention is such that when a control program that has already been executed is sequentially reversely executed,
It is characterized in that each movement command is executed by using the position argument of the immediately preceding movement command to trace back the path and return to the work origin.

In order to achieve the above object, the robot origin return control method according to a second aspect of the present invention uses one or a plurality of predetermined movement commands when sequentially executing a control program that has already been executed. It is characterized in that a part of the path is short-circuited and the operation origin is restored by skipping and performing the reverse operation.

[0014]

In the origin return control method according to claim 1,
In order to reduce interference by returning the robot to the origin along the same path as during normal work, a certain movement command and the position argument immediately before it are combined and executed in reverse. As described above, simply executing the work programs in reverse order cannot follow the same route when there are multiple types of commands such as MOVE and MOVES that move on different routes. It is possible to trace the same route and return to the origin by replacing the position started by the move command at the time of operation with the reached position at the time of return operation and combining a move command with the position argument immediately before it.

Further, in the home-return control method according to the second aspect, when it is clear that interference will occur in advance during the returning operation, by short-circuiting the interfering specific position,
This is to prevent interference. To short-circuit the path, one of the movement commands executed during normal operation can be skipped during the returning operation, and skipping one movement command short-circuits one path and skips two or more movement commands. By doing so, two or more paths can be short-circuited.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the origin return control method for a robot according to the present invention will be described below with reference to the drawings.

First Embodiment FIG. 1 shows the configuration of a robot control system of this embodiment, and FIG. 2 shows an input signal from a sequencer. When a forward signal is supplied from the forward / back signal input unit (sequencer) 10 to the interpreter 12 in the robot controller, the interpreter 12 analyzes the robot work program. The interpreter 12 has the functions of a forward interpreter and a return interpreter as will be described later, and executes the forward interpreter or the return interpreter according to the start signal STR or the return signal RTN. The work data analyzed by the interpreter 12 is supplied to the calculation unit 14, and the trajectory is generated and the coordinates are converted to output a command value to the servo amplifier 16. The servo amplifier 16 is
Further, this command value is supplied to the motor robot 18 to control the operation according to the work program. When the work program of the robot is the work program of FIG. 16 described above, when the activation signal STR is input, first, the MOVES
At P [1], it moves to a point P [1] in a linear trajectory, and then at MOVEP [2] it moves to a point P [2] on each axis. In this "MOVE" command, the tip trajectory of the robot is generally not a straight line as described above (Fig. 17).
reference). Hereinafter, the work program is sequentially executed to perform a predetermined work.

Consider a case where the robot is stopped by inputting an emergency stop when the robot moves to the position P [5]. At this time, the activation of the return operation "RTN" shown in Fig. 2 is input, and the interpreter 12 in the robot controller executes the return interpreter by this RTN to sequentially execute the work program, but with this return interpreter. Instead of simply reversely executing the work program as in the conventional case, each move command is executed using the position argument of the move command immediately before that, specifically, as shown in FIG. When moving from the position of [5] to the position of P [4], the move command “MOVES” corresponding to P [5] and the position argument P [4] immediately before that are combined, That is, the control command indicated by the broken line 3 is created and is reversely executed. FIG. 4 shows a return work program created by combining the move command and the preceding position argument in this way, and the return interpreter sequentially executes the return work program from bottom to top. Of. Then, during normal work (when executed by the forward interpreter), "MOV
The route moved by "E" returns with "MOVE", and "MOVE"
The route moved by "S" can be returned by "MOVES", and as shown in FIG. 5, the route (solid line) during normal work and the return route (broken line) can be matched. As described above, it is apparent that the coherence can be reduced by returning to the work origin along the same path as compared with the case shown in FIG.

Second Embodiment In the above-mentioned first embodiment, the case where the work program is composed of the move command and the input / output command is shown, but the present invention can be applied to the work program including other commands. You can

In the second embodiment, origin return control in the case of a work program including a command for designating a tool to be gripped by the robot according to the work will be described. FIG. 6 shows the work program of this embodiment, and the tool to be used is selected by the "TOOL" command. In FIG.
Two kinds of tools are selected by TOOL 1 and TOOL 2. Here, the teaching position P [1] of the robot and the like are determined in consideration of data such as the length of the tool when the tool is set. Therefore, in order to move correctly to the taught position, it is necessary to match the position with the tool used when the position was stored. In addition, in FIG. 6, TOOL 0
Means to release the tool.

When the work program shown in FIG. 6 is executed, the tools 1 and 2 are sequentially moved to P [1] to P [6] while being appropriately selected. Then, consider a case where an emergency stop is input and the robot stops when the robot moves to P [6]. As in the case of the first embodiment described above, a return work program is created by combining the move command and the position argument immediately before it, as shown in FIG. Here, if the return interpreter sequentially executes this return work program in reverse, when it moves to points P [4] and P [3]
The tool 2 is selected by 2, and the points P [2] and P [
1], the tool 1 is selected by TOOL 1 and an operation different from the forward operation is performed. As described above, when different tools are gripped, the possibility of colliding with other tools and devices increases even if the tool returns to the same path, and the coherence increases.

Therefore, even in the case of the work program including the tool selection command as described above, in order to return to the origin with low interference, in this embodiment, the tool number for the forward movement and the tool number for the returning movement are included in the tool selection command. You can describe. FIG. 8 shows an example of the returning work program of this embodiment corresponding to the work program of FIG. As is clear from the comparison with the returning work program of FIG. 7, the tool number of the TOOL command is TOOL 1,0.
The feature is that it is composed of two arguments as described above. The previous number means the selected tool number at the time of forward movement, and the latter number means the selected tool number at the time of returning operation. Then, during the forward movement, the forward interpreter selects the tool according to the previous number, and during the return operation, the return interpreter selects the tool according to the subsequent number.
Therefore, when the returning work program of FIG. 8 is sequentially reversely executed by the returning interpreter, the tool 1 is selected by TOOLs 2, 1 when moving to the points P [4] and P [3], and the points P [2] and P When moving to [1], the tool 1 is moved by TOOL 1,0 in a state where the tool is released. Therefore, it is possible to return to the origin with the same route and the same tool as during forward movement.

Third Embodiment In the first and second embodiments, the case where the robot is immediately returned to the origin from the emergency stop position has been described. However, depending on the situation, the operation is temporarily stopped during the returning operation of the robot, and the robot and It may be necessary to check the status of the peripheral device and then perform the returning operation again. For example, the robot may interfere with the jig unless the robot is temporarily stopped at a specific teaching position and the cylinder of the jig is moved. FIG. 10 shows an example of such a case, and when the robot moves from P [1] to P [5],
This is a case where another jig has moved to the position P [3]. In this case, if the robot is returned along the same path from the position of P [5], it will interfere with the jig 100 at P [3]. In order to deal with such a case, in the present embodiment, the FLAG command is inserted into the returning work program so that the robot temporarily stops when the robot reaches a specific teaching position during the returning operation. FIG. 9 shows an example of the returning work program according to the present embodiment, which includes the MOVE P [3] command and the MOVE command.
The FLAG command is inserted between the SP [4] commands. As a result, the point P [
4], the FLAG command is executed and the robot automatically pauses, so that the jig or the like can be moved to prevent interference. In addition, this FLAG
It goes without saying that the command is not executed by the forward interpreter and is not paused during the forward movement.

Fourth Embodiment In the above-described third embodiment, the FLAG command for temporarily stopping the robot when the robot reaches a specific position is inserted, but in the present embodiment, it is possible that interference may occur in advance. The robot is not returned to the position, but a part of the path at the time of forward movement is short-circuited and returned to the origin, so that there is no need of temporary stop and the coherence is reduced.

For this reason, in this embodiment, a switch is newly provided which is not executed only when returning to the operation command. This is denoted by N, which is set after the motion command. FIG. 11 shows an example of the work program of this embodiment. In FIG. 11, MOVE P [1
1] and the like are commands that are executed both forward and backward as in the above-described embodiments, and MOVES P [13] and N are commands that are executed only during forward movement and not during return. If an emergency stop is input during execution of such a work program, the return signal RTN is input and the return interpreter creates a return work program and executes it in reverse.
The return work program of FIG. 11 is as shown in FIG. Command MOVES P [that exists during forward movement
13] is skipped in the returning work program. Thus, if a part of the command for forward movement is skipped during the return operation, as shown in FIG. 13, a portion of the path during forward movement (point P [13] in FIG. 13) is skipped during the return operation. The point P [14] returns directly to the point P [12]. Therefore, even if the jig exists at the point P [13], it can return to the origin in a short time without causing any interference.

In this embodiment, the case where only one path is short-circuited has been described, but it is also possible to short-circuit two or more paths if necessary. In this case, it is only necessary to add N after the command to be skipped.

Fifth Embodiment In the above-described fourth embodiment, an example in which N is added to the movement command and a part of the route is short-circuited has been shown, but a new switch is added to the input / output command such as SWITCH and WAIT. It is also possible to configure so that it is executed only during forward movement or only during return movement.

FIG. 14 shows an example of the work program of this embodiment. SWITCH2, OFF, R and WA
IT 2, ON, and R are characteristic commands in this embodiment, and the rear R is a switch indicating that the command is executed only during the return operation. Therefore, when the robot makes an emergency stop during execution of the work program of FIG. 14 and the return command RTN is input, the return interpreter creates the return work program shown in FIG. 15 from the work program of FIG. 14 and sequentially performs reverse execution. . Here, SWITCH 2, OFF command, WAIT 2, ON command, SWITCH 2,
It should be noted that there is an ON command in the return work program. In this way, by setting a command to be executed only at the time of the returning operation, the jig is automatically moved from the path at the time of the returning operation, and it is not necessary to temporarily stop the jig as in the third embodiment described above. Further, unlike the fourth embodiment, it is possible to return to the origin on the same route and in a short time without short-circuiting a part of the route during forward movement.

It should be noted that the above-described embodiments are not independent of each other, and it is possible to appropriately combine them according to the situation to return the robot to the origin in the shortest time and with the lowest interference. For example, at a certain point, the jig can be automatically moved by signal input / output, but at a certain point, when the jig can be moved only by manual operation, the third embodiment and the fifth embodiment can be combined, and any combination can be used. Can be used.

[0030]

As described above, according to the origin return control method for a robot of the present invention, the structure is simple and the coherence is suppressed to a very small level, that is, without colliding with other jigs or the like. It is possible to surely return to the origin.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of sequencer input.

FIG. 3 is an explanatory diagram showing an example of a work program.

FIG. 4 is an explanatory diagram showing a returning work program of the work program of FIG.

FIG. 5 is an explanatory diagram showing a trajectory of the robot of the first embodiment.

FIG. 6 is an explanatory diagram showing an example of a work program.

FIG. 7 is an explanatory diagram showing a returning work program of the work program of FIG. 6;

FIG. 8 is an explanatory diagram showing a returning work program of the second embodiment corresponding to FIG. 6;

FIG. 9 is an explanatory diagram showing a returning work program according to a third embodiment.

FIG. 10 is an explanatory diagram showing the trajectory of the robot of the third embodiment.

FIG. 11 is an explanatory diagram showing an example of a work program.

12 is an explanatory diagram showing a returning work program of a fourth embodiment corresponding to FIG. 11. FIG.

FIG. 13 is an explanatory diagram showing the trajectory of the robot of the fourth embodiment.

FIG. 14 is an explanatory diagram showing an example of a work program.

FIG. 15 is an explanatory diagram showing a returning work program of a fifth embodiment corresponding to FIG. 14;

FIG. 16 is an explanatory diagram showing an example of a work program.

FIG. 17 is an explanatory diagram showing a trajectory of a conventional robot.

[Explanation of symbols]

 10 Input Unit 12 Interpreter 14 Computing Unit 16 Servo Amplifier 18 Motor Robot 100 Jig

Claims (2)

[Claims] 1. A control method for returning a robot that performs a series of operations along a desired path from a stop position to a work origin by sequentially executing a control program that includes a plurality of types of movement commands whose paths do not match. When the control program that has already been executed is sequentially reverse-executed, each movement command is executed by using the position argument of the immediately preceding movement command to trace back the path and return to the work origin. A method of returning to origin for a robot characterized by. 2. A control method for returning a robot that performs a series of operations along a desired path from a stop position to a work origin by sequentially executing a control program that includes a plurality of types of movement commands whose paths do not match. When the control programs that have already been executed are sequentially reverse-executed, a predetermined one or a plurality of movement commands are skipped and reverse-executed to short-circuit part of the path and return to the work origin. A method for returning to origin of a robot, which is characterized in that