JPH05265533A - Method for controlling robot - Google Patents

Abstract

PURPOSE:To easily retrieve a teaching point number near to a armtip control point from the armtip control point by selecting the teaching point in d memory in the order of sizes and shifting the control point to the aching point position after specification. CONSTITUTION:Teaching points of an armtip of a robot 1 along the operational path of the robot 1 are stored in a program storage means 23. An execution means 24 calculates the distance from the present position of the armtip control point of the robot 1 to the stored teaching points. In selecting an instruction step on a display unit 31 of a controller 3, that is, the teaching point of the prescribed distance, an execution means 24 shifts the armtip of the robot 1 to the teaching point. Thus, the control point of the armtip of the robot 1 and the teaching point distance are retrieved at its display, and the selected given control point can be operated as a control point. Thus, after moving the control point to the approximate position, the nearby teaching number can be found as soon as possible.

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 robot control method suitable for improving the ease of operation when searching for a teaching point in the vicinity of the control point of the hand of the robot. Regarding

[0002]

2. Description of the Related Art In a robot control method, a teaching point representing the position and orientation of a control point at the hand of the robot is stored in a storage device together with a number or name for identifying each teaching point. For these teaching points, the teaching point number or name is specified while actually moving the control points of the hand of the robot, and the work of storing the position and orientation of the control points of the hand required for the work as teaching points in the storage device is repeated. , Created by the so-called teaching method. In this way, a series of teaching point data stored in the storage device is read out by specifying a number or a name and output to the servo operation circuit, and as a result, the control point of the hand of the robot is
Move to a memorized position. Such a robot operation includes a case where an operator designates teaching points one by one in order to confirm a taught position and operates the robot manually, and a case in which the operator operates the first position stored for performing actual work. There is a case where the teaching points are automatically read and continuously operated. The former is called step driving or point movement, and the latter is called playback or automatic driving.

[0003]

In the prior art, when it is desired to know the actual position of the teaching point, the number or name of the teaching point is designated and the control point of the hand of the robot is moved to that position. You can However, conversely, when trying to know the number or name of the teaching point in the vicinity from the actual position of the control point of the hand of the robot, the teaching points stored by the point movement are designated in order from the beginning, and the actual robot Repeat the operation of moving the control point of the hand and confirming the position for each teaching point, or by automatic operation, automatically read from the stored first teaching point and operate continuously. There is a problem that it is necessary to stop the vehicle when it arrives at the target position, and it takes time by any method. In particular, the number of teaching points increases as the shape of the work, which is the work target of the robot, becomes complicated, and it becomes difficult to grasp the correspondence between the teaching points and their positions. Since the time required for this increases in proportion to the number of teaching points, there is a problem that a great number of man-hours are required for creating and correcting teaching data.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a control method capable of facilitating retrieval of a teaching point number in the vicinity of the control point position of the hand of the robot.

[0005]

The object is to previously store a plurality of teaching points of the hand of the robot along the movement path of the robot together with the teaching point numbers, and to store the above from the current position of the control point of the hand of the robot. This is achieved by calculating the distances to the plurality of taught points selected, selecting a teaching point of a predetermined distance, and moving the hand of the robot to the selected teaching point.

[0006]

The control point can be moved to an arbitrary selected teaching point by selecting a teaching point of a predetermined distance from the distance from the current position of the control point of the hand of the robot to the teaching point.

Specifically, the teaching point data of the robot is data representing the position and orientation of the control point of the hand of the robot, and is generally a vector composed of data having a degree of freedom (number of joints) or more of the robot. expressed. In the case of a 6-DOF robot with 6 joints, the data representing the position and orientation of the control point of the hand is, for example, P = (x, y, z, α, β, γ) (Formula 1) It is represented by. Here, x, y, and z are coordinate values representing the position of the control point of the hand of the robot, and α, β,
γ is an angle value representing the posture of the control point of the hand of the robot.

A robot operation program is made up of n sets of teaching points Pi (i = 1,2,3, ... n) as described above and information such as velocity values designating the moving velocity between them. Become.

The position and orientation of the control point of the hand of the robot are
It can be obtained from the value of the position detector of each joint of the robot. Now, the position and posture of the control point of the hand of the robot is Pc = (xc, yc, zc, αc, βc, γc) (Equation 2) Teaching point data stored in the storage device is Pi = (xi, yi, zi, αi, βi, γi) (i = 1,2,3, n) (Equation 3) In the present invention, the distance di between Pi and Pc is

[0010]

[Equation 4]

Then, the teaching point numbers i are arranged in ascending order of di. Here, since di is a positive number, di ² ≤dk ² when di≤dk. (J = 1,2,3,, n, k = 1,2,3,
, n) Therefore, instead of arranging the distances di in order of magnitude, di ² = (xi-xc) ² + (yi-yc) ² + (zi-zc) ² (i = 1,2,3,, n) (Equation 5) ) May be obtained and arranged in descending order of d ² . When the arrangement is completed, first, the teaching point number imin that minimizes di is selected and displayed. Hereinafter, each time the button for selecting the next teaching point is pressed, the teaching point numbers are selected and displayed in ascending order of di.

When the teaching point number i is obtained as described above, the teaching point P can be obtained by designating an arbitrary teaching point number i.
It is also possible to move the control point of the hand of the robot to the position of Pi by reading out from the storage device and outputting this to the servo operation circuit.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an apparatus according to an embodiment of the present invention. The robot 1 and the operating device 3 are connected to the robot control device 2, and the operation of the robot 1 is controlled by the robot control device 2 based on the input from the operating device 3. The robot control device 2 is intended to create a program in which a series of operations of the robot 1 are described one by one, and to execute the program to cause the robot 1 to operate as described in the program. The robot control device 2 includes a robot control unit 21, a teaching unit 22, a program storage unit 23, and an execution unit 24. The operation device 3 receives an operation for the robot control device 2 and displays information in the robot control device 2. The operation device 3 includes a display device 31 and an input device 32. The robot 1, the robot control device 2, and the operation device 3 constitute a robot of a typical teaching / execution system. A robot operation program is created by teaching, and the taught operation is performed by executing the program. Reproduce (playback). The program is created by the teaching means 23 by the operator operating the operating device 3, and is stored in the program storage means 23. The program describes various commands related to the operation of the robot 1. The created program is reproduced and executed by the execution means 24 when the operator operates the operation device 3. The execution means 24 designates a program to be executed from the programs stored in the program storage means 23 according to the input from the operation device 3, and reads out and executes the instructions in the program one by one. If the command is a motion command, the teaching point data in the program is read out and sent to the robot control means 21. The robot control means 21 outputs a servo command value 26 to the robot from the teaching point data and the servo current value 25 input from the robot to operate the robot. FIG. 2 is an operation flow showing the outline of the overall operation procedure of the present invention. First, the program is created in the teaching step 41, and then the program created in the executing step 42 is executed.

FIG. 3 is a flow chart for explaining the operation procedure in the teaching step 41. In the teaching step 41, the teaching means 22 performs the instruction according to the input from the operation device 3.
In step 301, a step in the program that is the target of subsequent operations is selected. The step is selected by moving the cursor on the step of the program displayed on the display device 31 of the operation device 3. The movement of the cursor is executed by pressing a cursor movement button in the input device 32. At 302, an operation for the selected step is selected. If addition or change is selected, the process proceeds to step 303, and if deletion is selected, the process proceeds to step 304. At 303, an instruction is input. To input a command, the operator operates the input device 32 of the operation device 3 to display the display device 20.
This is done by selecting one from a plurality of types of instructions 71 displayed in. The selected instruction 71 is stored in the relevant step of the relevant program in the program storage means 23. When the selected instruction 71 is a robot operation instruction, the teaching point is further taught. By pressing the robot manual operation button in the input device 32, the position and orientation of the control point of the robot hand is made to match the desired point, and by pressing the position teaching button in the input device 32, the robot hand control is performed. The position and orientation of the point are stored in the program storage means 23 at the teaching point of the program together with the teaching point number.

At 304, the instruction is deleted. By pressing the delete button in the input device 32, the command stored in the step of the program in the program storage means 23 is deleted. When the deleted instruction 71 is a robot operation instruction, the teaching point stored in the teaching point of the program in the program storage means 23 is deleted. At 305, it is determined whether the command and the teaching point are excessive or insufficient. 3 if there is an excess or deficiency in commands or teaching points
01, if there is no excess or deficiency, proceed to 306.

By repeating the above steps 301 to 305, the program 7 is created in the program storage means 23.

At 306, the teaching point is confirmed. To confirm the teaching point, the teaching point is selected by moving the cursor on the step of the operation command displayed on the display device 31 of the operation device 3, and the point movement button in the input device 32 is pressed to move the robot. It is executed by moving the control point of the hand to the teaching point. Here, the robot operates while pressing the point movement button, stops when the point movement button is stopped, and stops when the control point at the hand of the robot reaches the teaching point. By executing the above operation of the button for each teaching point, the actual position of the teaching point in the program can be confirmed. At 307, it is determined from the result of 306 whether there is an excess or deficiency of the teaching point and whether there is an error in the position. If there is an excess or deficiency of the teaching point, the process returns to 301. finish.

By repeating the above steps 301 to 307, the program 7 with few errors is created in the program storage means 23. Where 306 and 306
It is necessary to find the correspondence between the teaching point and the actual position in 301 after the error of the teaching point is found in. In the conventional control method, there is a means for finding the position from the teaching point number, but there is no means for finding the teaching point from the position. Therefore, when an error or excess or deficiency of the position is found in 306, the operator makes a note of the teaching point number, and when the step to be additionally changed is selected in 301, it is displayed based on the above note. It was necessary to find and select the step from the programs displayed on the device 31, and it took time to select the step. In particular, the number of teaching points increases as the shape of the work, which is the work target of the robot, becomes complicated, and it becomes difficult to grasp the correspondence between the teaching points and their positions. Since the time required for this increases in proportion to the number of teaching points, there is a problem that a great number of man-hours are required for creating and correcting teaching data.

A control method that facilitates the retrieval of a teaching point in the vicinity of the current position of the control point of the hand of the robot will be specifically described below. First, the related data structure will be described. FIG. 4 is a diagram showing a data structure of one program 7 in the embodiment of the present invention. Since the program 7 is created for each unit of work, the program storage means 23 stores a plurality of programs 7. One program 7 is composed of a set of commands 71, a set of teaching points 72, and other information necessary for controlling the operation of the robot 1. Here, the instructions 71 and the teaching points 72 related to the present invention will be described, and descriptions of other information not related to the present invention will be omitted. The command 71 is a series of motions of the robot 1 classified for each motion element, for example, a robot speed command, a robot motion command, an interpolation command, an acceleration command, an input / output command,
There are branch instructions and numerical operation instructions. During the program,
These commands are selected and stored in the order required for robot operation.

The teaching point 72 is the position data designated in the robot operation command, and is the data of the above-mentioned (Equation 3) format. The teaching points 72 are stored in the program 7 in the order of teaching point numbers for identifying individual teaching points. 5 and 6
FIG. 6 is a diagram showing a data structure of a teaching point search process in one embodiment of the present invention. The teaching point-distance correspondence table 8 in FIG.
It is a table for storing a set of a teaching point number and a distance from the control point of the robot hand to each teaching point in the order of the teaching point number,
The teaching point-distance correspondence table 8 of FIG. 6 is a vote for storing a set of teaching point numbers and distances from the control point of the hand of the robot to each teaching point, sorted in the order of distance. 7 is shown in Table 8 above.
An example of the teaching point shown in FIG. How to obtain the teaching point-distance correspondence table 8 and how to use it will be described later.

FIG. 8 is a flow chart showing the operation procedure of the teaching point search method in one embodiment of the present invention. First, at 601, the control point at the hand of the robot is moved to an approximate position of the teaching point to be searched. Next, at 602, the teaching point search button in the input device 32 for starting the search is pressed. Then, the teaching point search start processing is started in 603, the teaching point having the smallest distance from the control point of the robot hand is obtained, and the cursor is moved to the step of the operation command corresponding to the teaching point in 604 and displayed. It is displayed on the device 31.

After the teaching point is obtained as described above, the operator
One of four operations 605, 606, 601 and 607 can be executed. Reference numerals 605 and 608 are confirmations of teaching points by the control method described in 306 of FIG. To confirm the teaching point, press the point movement button in the input device 32 to display the control point of the hand of the robot on the display device 3.
It is executed by moving to the teaching point designated by the cursor on the step of the operation command displayed in 1.
At 606, the robot operates while pressing the point movement button, stops when the point movement button is stopped, and stops when the control point at the hand of the robot reaches the teaching point. When the point movement is completed, the process returns to 604.

Reference numerals 606 and 609 are re-searches for teaching points. By pushing the teaching point re-search button in the input device 32 at 606, the teaching point re-search process 609 is started,
The teaching point next to the teaching point obtained in 03 is searched and 60
At 4, the cursor moves to the step of the operation command corresponding to the teaching point and is displayed on the display device 31. By repeatedly executing the steps 605 and 608 and 606 and 609, the teaching points can be traced in the order closer to the position where the search is started. If the desired teaching point is not reached even by these operations, the process returns to 601 and the search start position is changed by a manual operation, and then the teaching point search can be started again from 602. When the desired teaching point is reached, the teaching point search end button in the input device 32 is pressed at 607 to end the teaching point search.

Next, details of the teaching point search start processing will be described. FIG. 9 is a flowchart of the teaching point search start processing in the embodiment of the present invention. 701, 702, 7
In the loop of 04 and 703, the set of the teaching point number i and the square of the distance di ² from the control point of the hand of the robot at the start of the search is stored in the teaching point-distance correspondence table 8 in the order of the teaching point numbers. .. Here, di ² is the value obtained by the above (Equation 5). FIG. 5 shows a teaching point-distance correspondence table 8 after the above teaching point calculation.
Indicates. After exiting the above loop, at 705, the teaching point-
Distance squared di ² sets of distance from the control point of the hand of the correspondence table of the teaching point number i as a search starting in 8 robot sorts di ² as a key. Now, assuming that the control point and the teaching point of the hand of the robot have a positional relationship as shown in FIG.
The teaching point-distance correspondence table 8 after sorting is as shown in FIG. At 706, m indicating the search order is set to 1 which stores the teaching point having the smallest distance di ² , and at 707, the teaching point number i is obtained from the above-mentioned m by the teaching point-distance correspondence table 8. From the above 706 and 707, the number of the teaching point having the minimum distance from the control point of the hand of the robot at the start of the search is obtained.

Next, details of the teaching point re-search process will be described. FIG. 10 is a flowchart of the teaching point re-search process in the embodiment of the present invention. In step 801, the value of the search order m is determined. If m <n, that is, if there is a next teaching point, the search order m is incremented by 1 in step 802. If m = n, that is, if there is no next closest teaching point, the search order m is set to 1 in 803. In 804, m according to the teaching point-distance correspondence table 8
The teaching point number i is obtained from 801, 802, 80
According to 4, the teaching point next to the previously selected teaching point and having a short distance from the control point of the hand of the robot at the start of the search is obtained. Further, if the previously selected teaching point is the teaching point having the largest distance from the control point of the robot's hand at the start of the search, 801, 803, and 804 are used to determine the robot's hand at the start of the search again. A teaching point that minimizes the distance from the control point is obtained.

In the above embodiment, the set of the squares di ² of the distance from the control point of the hand of the robot at the start of the search to each teaching point is obtained by (Equation 5). However, since only the position of the teaching point is taken into consideration in (Equation 5), when there are a plurality of teaching points having different postures at the same position, it takes time to search for the teaching point having the desired position and posture. This may occur.
Therefore, after the distance squared di ² is calculated by (Equation 5), if there are a plurality of teaching points having the same distance, the posture of the work point of the hand of the robot at the start of the search and the above-mentioned The distance d'i of the posture data between the teaching points is obtained, and the teaching points having the same di are sorted further on d'i. Now, assuming that the position and orientation Pc of the hand of the robot at the start of the search are represented by (Equation 2) and the teaching point data Pi is represented by (Equation 3), d'i is obtained by (Equation 6). ..

[0027]

[Equation 6]

Since d'i ≧ 0 (positive), d '
If j ≦ d′ k, then d′ j ² ≦ d′ k ² (j = 1,2,3,, n,
k = 1,2,3, n). Therefore, instead of d'i, d'i ² = (αi-αc) ² + (βi-βc) ² + (γi-γc) ² (i = 1,2,3, n) (Equation 7) First, use this as a key and sort by size. As a result, if the distance from the control point of the hand of the robot at the start of search is small and the distances are equal,
Since the teaching points can be searched in the order in which the postures are close to each other, even when there are a plurality of teaching points having different postures at the same position, the teaching points of the desired position and posture can be searched in a short time.

Similarly, as a countermeasure when there are a plurality of teaching points having different postures at the same position, there is a method of sequentially arranging the teaching point numbers. Since the teaching point numbers are assigned according to the execution order, the teaching points at the same position are searched in consideration of the execution order. That is, after the square of the distance is calculated by (Equation 5), if there are a plurality of teaching points having the same distance, the teaching points are further sorted between the teaching points. As a result, when the distance from the control point of the hand of the robot at the start of the search is small and the distances are equal, the teach points can be searched in the order of the teach point numbers. Even when there are a plurality of teaching points, it is possible to retrieve the desired teaching point in an order that takes the execution order into consideration in a short time.

Further, in the above embodiments, it has been sorted teaching point the square di ² of the control points of the hand of the search start time of the robot distance between the teaching point as a key. However, the present invention is not limited to this, and first pays attention to the posture data, and squares the distance d′ i ² of the posture of the work point of the hand of the robot at the start of the search and the posture data between the teaching points. Then, there is a method of sorting the teaching points using d'i ² as a key. Here, d'i ² is obtained by the (Equation 7) as in the above. In (Equation 7), since only the posture of the teaching point is taken into consideration, when there are a plurality of teaching points at the same posture but at different positions, it takes time to search for the teaching point having the desired position and posture. May take. Then, after the square of the distance of the posture d'i ² is obtained by (Equation 7), if there are a plurality of teaching points of the same posture, the work point of the hand of the robot at the start of the search and The square of the distance d'i ² between the teaching points is obtained, and the teaching points having the same d'i ² are further sorted with respect to di ² .
As a result, the teaching points can be searched in ascending order of posture from the control point of the robot's hand at the start of the search, and in the case of the same posture, the teaching points can be searched in ascending order of distance. Even when there are a plurality of teaching points, it is possible to search the teaching points of the desired position and posture in a short time while focusing on the posture.

Similarly, as a countermeasure when there are a plurality of teaching points at the same posture and at different positions, there is a method of sequentially arranging the teaching point numbers. Since the teaching point numbers are assigned according to the execution order, the teaching points in the same posture are searched in consideration of the execution order. That is, after the square of the distance of the posture is obtained by (Equation 7), when there are a plurality of teaching points having the same posture, the teaching points are further sorted between the teaching points.

As a result, since the teaching points can be searched in the order of the teaching point number in the order close to the posture of the control point of the hand of the robot at the start of the search, and when the postures are the same, the positions are the same and different. Even if there are multiple teaching points,
The teaching point of the desired posture can be searched in a short time in consideration of the execution order.

[0033]

According to the present invention, in the teaching operation of robot operation, the control point of the robot hand is searched and displayed, and the control point of the robot hand is moved to the selected teaching point. Can be made Therefore, even an operator who does not know the relationship between the teaching point number and the position in advance can move the control point of the hand to the approximate position of the teaching point and then, for example, determine the closest teaching point number and its accurate position for a short time. You can know in a moment. Therefore, when the teaching point is added, changed, or deleted, the target teaching point can be quickly known, and the number of steps for creating and modifying the robot operation program can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an outline of an overall operation procedure in one embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation procedure of a teaching process according to an embodiment of the present invention.

FIG. 4 is a diagram showing a data structure of a program in an embodiment of the present invention.

FIG. 5 is a diagram showing a data structure of a teaching point search process according to an embodiment of the present invention.

FIG. 6 is a diagram showing a data structure after sorting in the teaching point search processing according to the embodiment of the present invention.

FIG. 7 is a diagram showing an example of teaching points in an embodiment of the present invention.

FIG. 8 is a flowchart illustrating an operation procedure of a teaching point search method according to an embodiment of the present invention.

FIG. 9 is a flowchart of teaching point search start processing according to an embodiment of the present invention.

FIG. 10 is a flowchart of teaching point re-search processing according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Robot, 2 ... Robot control device, 3 ... Operating device,
7 ... Program, 8 ... Teaching point-distance correspondence table, 21 ... Robot control means, 22 ... Teaching means, 23 ... Program storage means, 24 ... Execution means, 31 ... Display device, 32 ... Input device, 41 ... Teaching process, 42 ... Execution process, 71 ... Instruction, 7
2 ... Teaching point.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Seshita 7-1, 1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Narashino Factory (72) Inventor Shigeyoshi Yokoyama 7-1, Higashi Narashino, Narashino City, Chiba Prefecture No. Hitachi Narashino Factory (72) Inventor Sumio Washio 7-11 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Keiyo Engineering Co., Ltd.

Claims (5)

[Claims] 1. A plurality of teaching points of a hand of the robot along a motion path of the robot are stored in advance together with a teaching point number, and from the current position of the control point of the hand of the robot to the plurality of stored teaching points. A method for controlling a robot, characterized in that a distance is obtained by calculation, a teaching point having a predetermined distance is selected, and the hand of the robot is moved to the selected teaching point. 2. The method of controlling a robot according to claim 1, wherein the stored teaching points are ordered in ascending order of distance based on the distance obtained by the calculation. 3. When ordering the teaching points stored in the ascending order of distance, it is determined that teaching points having the same distance are closer to each other with a smaller teaching point number. Control method of the described robot. 4. When the control point of the hand of the robot is moved to a selected teaching point, the control point moves based on the operation of a designated button, and the control point is moved to the selected teaching point. The robot control method according to claim 1, 2 or 3, wherein the movement of the control point is stopped based on the arrival. 5. A plurality of teaching points including posture data of the hand of the robot along a motion path of the robot are stored in advance together with a teaching point number, and the current posture of the control point of the hand of the robot and the stored plurality of the stored points. A method for controlling a robot, characterized in that a difference between the postures of teaching points is obtained by calculation, and a hand of the robot is moved to a teaching point having a selected predetermined posture difference.