JP2732034B2 - Robot controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for controlling a plurality of industrial robots, and more particularly to a robot controller for controlling a plurality of movable robots on the same rail.

[0002]

2. Description of the Related Art In order to efficiently perform a large number of machining operations on one work, there is a configuration in which a plurality of robots having different functions which can be moved on the same rail are installed.
According to this configuration, in order to shorten the cycle time, the installation intervals of the robots must be narrowed and arranged, so that interference between adjacent robots becomes a big problem, and a method to solve this has been conceived. I have. For example,
Japanese Patent Publication No. 6-6279 discloses a method of controlling a plurality of traveling devices which are installed on the same rail and on which a robot can be mounted, and detects that an adjacent traveling device has approached a predetermined distance. A method is shown in which both traveling devices are stopped, thereby preventing interference of the traveling devices.

[0003] Further, when welding a plate-shaped workpiece by a welding robot or the like, the workpiece is gripped by a plurality of clamp devices that can be moved on the same rail.
There is a method in which a clamp device is moved to a position near a predetermined welding position of a workpiece, and a welding robot is moved to this welding position to perform a welding operation. Japanese Patent Application Laid-Open No. 6-15585 is for controlling a plurality of clamp devices installed on the same rail and capable of supporting a work. The method of changing the workpiece gripping position of the clamp device is shown.

In controlling a plurality of traveling devices and clamping devices disclosed in the above-mentioned publications, the operations of these devices are executed in consideration of interference between adjacent devices and synchronism with a device that performs joint work. You have to create an action program to make it work.

[0005]

However, it is inefficient to create an operation program individually for each traveling device and each clamping device, and it is difficult to change the operation program when the work is changed. Inflexible. For example, in the case of an operation in which the clamp devices are sequentially positioned at a plurality of set positions while maintaining a constant interval between the clamp devices, the positioning position of each clamp device is individually set for the control device of each clamp device. According to the instruction, when the number of clamping devices is large, the operation of changing the operation program becomes very complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control system for a plurality of movable robots on the same rail without individually specifying the positioning position for each robot. To provide a control device that can calculate the value

[0007]

Therefore, according to the present invention, one of a plurality of movable robots is set as a master robot, robots other than the master robot are set as slave robots, and positioning positions of these robots are determined. A master robot position storage means for storing a positioning position of the master robot; a relative displacement vector calculation means for calculating a relative displacement vector indicating a positional relationship between the master robot and each slave robot; and a relative displacement vector. And a slave robot position for calculating the positioning position of each slave robot from the master robot's positioning position stored in the master robot position storage means and the relative displacement vector stored in the relative displacement vector storage means. With calculation means By providing a robot control apparatus characterized by, it has solved the problems of the prior art described above.

Further, instead of the slave robot described above, a plurality of movable clamp devices may be arranged on the same rail.

[0009]

[Function] The positioning position of each slave robot is calculated from the relative displacement vector indicating the positional relationship between the master robot and each slave robot and the specified positioning position of the master robot. , The positioning position of each slave robot is determined only by specifying the positioning position of the master robot.

[0010] For example, if the above-mentioned master robot is a spot welding robot, and a plurality of clamping devices for supporting a work to be welded are arranged on the same rail instead of the slave robot, the work of the work can be performed. The present invention can be applied to a spot welding robot in which a clamp device moves corresponding to a plurality of welding positions.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a spot gun 2 at the tip of the wrist of the robot 1.
1 shows a configuration of a system for performing spot welding on a workpiece 11 which is a plate material by attaching a workpiece. The work 1 is mounted on the rail 3 as a clamp device for fixing the work 11.
Two clamp tables 4 and 7 for gripping 1 from both sides are arranged, and the inner clamp table 4 is movable so that the grip position can be changed according to the size of the work 11.
On the other hand, the clamp table 7 is fixed. Two movable clamp tables 5, 6 for holding the welding position are arranged between the clamp tables 4, 7, and the holding positions of the clamp tables 5, 6 can be changed depending on the welding position. So that it can be moved. At the time of welding, the clamp tables 5 and 6 move to both sides of the welding position, thereby eliminating bending of the work 11 and performing high-precision welding.

A robot controller 8 for controlling the robot 1
Is connected to the robot 1 by a cable 9, and a positioning control device 12 for controlling the clamp tables 4, 5, 6 is connected to the clamp tables 4, 5, 6 by a cable 10, respectively. The robot controller 8 has the cable 1
The clamp tables 4, 5, and 6 can be simultaneously controlled by transmitting data to the positioning control device 12 connected by 3 by bus communication, serial communication, or the like.

FIG. 7 shows a detailed configuration of the robot control device 8.
, The width of the clamp tables 4, 5, 6, 7; the interval between adjacent clamp tables among the clamp tables 4, 5, 6, 7; and the setting data such as the center position of the adjacent clamp tables. The relative displacement vector calculating means 28 in the robot operation program 24 calculates a relative displacement vector based on the setting data received by the data input unit 22, and the relative displacement vector is calculated by the relative displacement vector storing means 26 in the storage device 21. Recorded in the storage device 21. Similarly, the welding position of the robot 1 received by the data input unit 22 is stored in the storage device 2 by the master robot position storage unit 25.
1 is recorded.

A series of these controls are controlled by a microcomputer 23. The microcomputer 23 reads out the welding position of the robot 1 from the storage device 21 and transmits the welding position to the robot 1 actuator controller 29. The microcomputer 23 reads the relative displacement vector from the storage device 21 and calculates the slave robot position calculating means 27 in the robot operation program 24 from the relative displacement vector and the welding position of the robot 1 previously read out. Calculate the positioning positions of 4, 5, and 6 and calculate the result.
0, and is transmitted to the clamp base 5 actuator control unit 31 and the clamp base 6 actuator control unit 32, respectively. The actuator control units 29, 30, 31, and 32
A command is issued to move the robot 1 and each of the clamp tables 4, 5, and 6 to the transmitted welding position and positioning position.

The blocks are connected by bus communication, serial communication, or the like, and, among the blocks, actuator control units 30, 31, 32 for controlling the clamp table.
Are built in the positioning control device 12, and the other blocks are built in the robot control device 8.

Next, a method of calculating the positioning positions of the clamp tables 4, 5, and 6 will be described. As shown in FIG. 8, the coordinate system of the robot 1, that is, the master robot coordinate system (X, Y,
Z) and a coordinate system of the clamp tables 4, 5, and 6, ie, a slave robot coordinate system (x, y, z). As shown in FIG. 1, in this embodiment, the robot 1 and the rail 3 are both installed on the floor surface, and each clamp table moves on the rail in parallel with the floor surface. Therefore, for convenience, the master robot coordinate system ( The XY plane of (X, Y, Z) and the xy plane of the slave robot coordinate system (x, y, z) are assumed to be the same plane, and the Z axis of the master robot coordinate system (X, Y, Z) and the slave robot coordinates It is assumed that the z-axis of the system (x, y, z) has a parallel axis relationship.

The slave robot coordinate system (x, y,
The x-axis of z) is coaxial with the movable direction of each clamp table, and the coordinate origin position of the slave robot coordinate system (x, y, z) is the position of the fixed clamp table 7. Further, the coordinate origin position of the slave robot coordinate system (x, y, z) on the master robot coordinate system (X, Y, Z) is set to (Xc, Yc, Zc).
The inclination of the rail in the master robot coordinate system (X, Y, Z), that is, the angle between the X axis and the x axis is θ, and these values are set in the robot controller 8 in advance.

The dimensions Lw of the work 11 shown in FIG. 2 and the clamp table 4 shown in FIG.
The width Ld of 5, 6, 7 and the distance Lp between the clamp tables 5, 6 shown in FIG. 3 are set in advance. In addition, the welding position (Xn, Xn, X) of the robot 1 in the master robot coordinate system (X, Y, Z).
Yn, Zn) are also input to the robot controller 8 in advance. This value is stored in the storage device 21 by the master robot position storage means 25 as the master robot position.

The positioning control device 12 calculates a positioning position of the clamp table 4 for gripping one end of the work 11 from the transmitted dimension Lw of the work 11. Since the work end of the clamp table 7 is set to the origin (0) as described above, the positioning position of the clamp table 4 is equal to the dimension Lw of the work 11.

Next, the positioning control device 12 calculates the positioning positions of the clamp tables 5, 6. First, the welding position (Xn, Yn, Zn) of the robot 1 in the preset master robot coordinate system (X, Y, Z) is set to the welding position in the slave robot coordinate system (x, y, z). Position (X
n ', Yn', Zn '). Since the x axis of the slave robot coordinate system (x, y, z) is coaxial with the movable direction of each clamp table, the welding position in the slave robot coordinate system (x, y, z) is (Xn ', 0, 0). ), And Xn 'is the distance from the work end of the clamp base 7 to the welding position. Master robot coordinate system (X,
Y, Z) X-axis and slave robot coordinate system (x, y,
Since the angle between the x-axis of z) and θ is θ, the coordinate system of the master robot (X, Y, Z) is changed from the coordinate system of the slave robot (x,
y, z) is as shown in equation (1).

[0021]

(Equation 1)

Using the transformation matrix of equation (1), the welding position (Xn ', Y) in the slave robot coordinate system (x, y, z)
n ′, Zn ′) are as shown in equation (2).

[0023]

(Equation 2)

However, the slave robot coordinate system (x,
Since the x axis of (y, z) is coaxial with the movable direction of each clamp table, only the x component of the equation (2), that is, Xn 'shown in the equation (3), needs to be obtained. The welding position in the slave robot coordinate system (x, y, z) was calculated by equation (3).

[0025]

(Equation 3)

Therefore, the positioning position Xa of the clamp table 5 and the positioning position Xb of the clamp table 6 shown in FIG.
Equations (4) and (5) are obtained from the equation (3) and the distance Lp between the clamp table 5 and the clamp table 6, respectively. Here, the distance Lp between the clamp table 5 and the clamp table 6 may be any value as long as the spot gun 2 does not interfere with the clamp table 5 and the clamp table 6 during welding.

[0027]

(Equation 4)

According to the equations (4) and (5), the clamp table 5
Positioning position Xa and clamping table 6 positioning position Xb
Is calculated. Of the variables in Expressions (4) and (5), those determined by the installation position of the device are extracted, and if this is calculated in advance, the position of the positioning position can be calculated. Calculation becomes easier. That is, among the variables in the equations (4) and (5), the master robot coordinate system (X, Y, Z)
The inclination θ of the rails in the coordinate origin position (Xc, Yc, Zc) of the slave robot coordinate system (x, y, z) and the master robot coordinate system (X, Y, Z) is Since it is determined by the installation position, it does not change unless the arrangement positions of the robot 1 and the rail 3 are changed. In addition, the distance Lp between the clamp table 5 and the clamp table 6 may be a value that does not cause the spot gun 2 to interfere with the clamp table 5 and the clamp table 6, and this value is also unchanged unless the spot gun 2 is changed. Accordingly, the relative displacement vector representing the relative displacement between the clamp table 5 and the clamp table 6 with the robot 1 is given by the following equation (6), where Xa ′ and Xb ′ are the relative displacement vectors of the clamp table 5 and the clamp table 6. Equation (7) is obtained.

[0029]

(Equation 5)

Using the relative displacement vectors Xa 'and Xb', the positioning position Xa of the clamp table 5 and the positioning position X of the clamp table 6 obtained by the equations (4) and (5).
When b is expressed, it becomes as shown in Formula (8) and Formula (9).

[0031]

(Equation 6)

Since the positioning positions of the clamp tables 4, 5, and 6 have been calculated as described above, the robot controller 8 transmits the calculated positioning positions of the clamp tables 4, 5, and 6 to the positioning controller 12, and performs positioning. The controller 12 controls the respective actuator controllers 30 and 3 so as to move to the positioning positions calculated with respect to the clamp tables 4, 5 and 6.
1 and 32. The clamp tables 4, 5, and 6 are moved to the positioning positions instructed by the respective actuator controllers 30, 31, and 32, and are operated to clamp the work 11 after the movement is completed. Pressing causes the robot 1 to perform welding.

Further, as shown in FIG. 5, if the width Ld of each clamp table is set in advance, the robot controller 8 moves the clamp table as shown in FIG. , Lb, and Lc are calculated, and if there is interference (if any one of La, Lb, and Lc is zero or negative), an error is displayed and the movement of the clamp table can be stopped. Spacing L of each clamp base
a, Lb, and Lc can be obtained by Expressions (10) to (12).

[0034]

(Equation 7)

According to this embodiment, since the positioning position of the clamp table 4 for gripping one end of the work 11 does not need to be directly instructed by the operator, when the size of the work 11 is changed, the input data is changed by this size. Can be changed.
Further, since the operator does not need to directly instruct the positioning positions of the clamp tables 5 and 6 for grasping the welding positions, the positioning positions of the clamp tables 5 and 6 are calculated only by instructing the welding positions of the robot 1.

In this embodiment, the case of spot welding has been described. However, the present invention is not limited to this application, but can be applied to all applications such as assembly and processing.

[0037]

According to the present invention, the relative displacement vector indicating the positional relationship between the master robot and each slave robot and the designated positioning position of the master robot are calculated based on the relative displacement vector.
Since the positioning position of each slave robot is calculated, the positioning position of each slave robot is automatically determined without being individually specified.

In the case where the master robot is a spot welding robot and a plurality of clamping devices for supporting the work to be welded are arranged on the same rail in place of the slave robot, the size of the work and the welding position may be reduced. Since the positioning position of the clamp device is automatically calculated, it is possible to flexibly cope with workpieces with different workpiece dimensions and welding positions using the same equipment without changing the setup. The time was shortened and the operation efficiency of the equipment was improved.

Further, as for the operability at the time of teaching, since only one robot needs to be taught, programming can be facilitated by setting a few parameters, and the teaching time is greatly reduced. It became possible.

Furthermore, by eliminating the programming of the slave robot, programming errors by the operator can be greatly reduced, and the debugging time of the program has been reduced.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a system for spot welding a work 11 by attaching a spot gun 2 to a tip end of a wrist of a robot 1 according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating dimensions of a work 11 held by clamp tables 4, 5, 6, and 7;

FIG. 3 shows an interval L between clamp tables 5 and 6 for holding a welding position.
It is a figure which shows p.

FIG. 4 is a diagram showing calculated welding positions Xn ′ and positioning positions Xa and Xb of clamp tables 5 and 6 supporting the welding positions.

FIG. 5 is a diagram illustrating a width Ld of a clamp table.

FIG. 6 shows calculated distances La, Lb, and L between clamp tables.
It is a figure showing c.

FIG. 7 is a diagram showing a detailed configuration of the robot control device 8;

FIG. 8 is a diagram showing a coordinate system of the robot 1, that is, a master robot coordinate system (X, Y, Z), and a coordinate system of the clamp tables 4, 5, and 6, that is, a slave robot coordinate system (x, y, z). .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Robot 3 Rails 4, 5, 6, 7 Clamping device (clamp table) 8 Master robot control device (Robot control device) 12 Slave robot control device (Positioning control device) 25 Master robot position storage means 26 Relative displacement vector storage means 27 Slave robot position calculation means 28 Relative displacement vector calculation means

Claims (2)

(57) [Claims] A robot controller for controlling one of a plurality of movable robots as a master robot, a robot other than the master robot as a slave robot, and controlling the positioning position of these robots.
Master robot position storage means for storing a positioning position of the master robot; relative displacement vector calculation means for calculating a relative displacement vector indicating a positional relationship between the master robot and each slave robot; and a relative storage for storing the relative displacement vector. Displacement vector storage means, and slave robot position calculation means for calculating the positioning position of each slave robot from the positioning position of the master robot stored in the master robot position storage means and the relative displacement vector stored in the relative displacement vector storage means And a robot controller comprising: 2. The robot controller according to claim 1, wherein the slave robot is a plurality of movable clamp devices arranged on the same rail.