JPH07314361A - Robot control method - Google Patents

Abstract

PURPOSE:To control a multi-axis robot at a low cost without requiring high speed action or positioning, or without requiring necessity of simultaneous control of plural axes. CONSTITUTION:An axis control circuit 42 and a servo amplifier 43 to be mounted on a control device 4 is for one axis only, a control axis changing device 5 is installed on a multi-axis robot 1, and an output of the servo amplifier 43 is changed to be connected to one servo motor 11-1n selected based on a command from the control device 4. The axis control circuit 42 and the servo amplifier 43 of the control device 4 can be used commonly for the plural servo motors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot control system, and more particularly to a robot control system for a multi-axis robot which does not need to be operated or positioned at high speed and need not simultaneously control a plurality of axes.

[0002]

2. Description of the Related Art In a conventional robot control system, control of a multi-axis robot is generally performed by mounting axis control circuits and servo amplifiers for the number of axes in a control device and connecting the robot and the control device with a cable. Done in a configuration. This configuration is due to the need to simultaneously control multiple axes in order to position the robot at high speed.

FIG. 5 is a diagram showing a schematic configuration of a conventional robot control system. In this figure, for example, a multi-axis robot 1 having four axes has four servo motors 11, 12, 1
It is equipped with 3 and 14. These servo motors 11,
In order to control 12, 13, 14 individually, the control device 2 has control circuits for four axes, that is, axis control circuits 21, 22,
23, 24 and servo amplifiers 25, 26, 27, 28 are mounted. Since the servomotors 11, 12, 13, and 14 are controlled by a dedicated control circuit, the multi-axis robot and the control device are connected by independent connecting cables 3 for the number of axes. According to this configuration, the four servo motors can be controlled simultaneously or individually.

[0004]

However, in a multi-axis robot, there is no time constraint such that it does not need to be operated or positioned at high speed, and it is not necessary to control a plurality of axes at the same time. Some are not. For example, in a manufacturing line, when trying to fix a flowing work, instead of switching and using multiple jigs prepared according to the shape and size of the work, various shapes and sizes can be used only by teaching operation. There are times when a robot that can handle a workpiece is used. In such a robot,
Once fixed or after positioning, it is stopped until the machining of the workpiece is completed.Therefore, if the movement that matches the movement of the workpiece can be performed at the time of positioning, the movement does not need to be a special high speed, and multiple axes can be operated simultaneously. You don't even have to work.

However, even in the control of the robot used for such a jig purpose, according to the conventional robot control system, the control device side is equipped with the same number of axis control circuits as the number of axes which are not simultaneously controlled. ing. This is over-specification and high in cost. In addition, the number of control cables required for connecting to the robot is increased, resulting in an increase in cost.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a robot control system for controlling a multi-axis robot having a plurality of control axes which are not simultaneously controlled. .

[0007]

In order to solve the above-mentioned problems, the present invention provides a robot control system for controlling a multi-axis robot having a plurality of control axes which are not controlled at the same time. A control device having a servo amplifier and the multi-axis robot are installed, and the control device is connected to the control device by a connection cable composed of a signal line for one axis, and the output of the servo amplifier is selected based on a command from the control device. And a control axis switching device for switching to connect to one of the plurality of servo motors.

[0008]

According to the above-mentioned means, the control axis switching device switches the output from the servo amplifier according to the axis to be controlled, and controls the plurality of servo motors by switching one axis at a time. With this, even if the control device has only one axis control circuit and one servo amplifier, it is possible to switch a plurality of axes and control the axes one by one.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a robot control system of the present invention. In this figure, reference numeral 1 denotes a multi-axis robot having a plurality of control axes, and servo motors 11 to 11 corresponding to the number of axes are provided.
It has 1n. Each servo motor 11-1n has a built-in pulse coder and outputs position data when necessary. 4 is a control device, which includes a robot control circuit 41,
An axis control circuit 42 for one axis, a servo amplifier 43, and an axis switching signal generation circuit 44 are provided. Reference numeral 5 denotes a control axis switching device built in the multi-axis robot 1, which includes a motor power switching circuit 51, a decoder circuit 52, and a selector circuit 53.
It has and.

The robot control circuit 41 of the controller 4 controls the entire robot control system including the multi-axis robot 1. For example, position calculation is performed based on position data from the pulse coders of the servomotors 11 to 1n. It has the functions of executing commands, issuing servo system commands, interfacing with peripheral devices and teaching operation panels, and applying brakes to prevent uncontrolled axes from moving. The axis switching signal generation circuit 44 generates an axis switching signal according to which axis the robot control circuit 41 controls, and sends it to the control axis switching device 5 via the axis switching signal line 31. The axis control circuit 42 and the servo amplifier 43 perform control operations for the servomotors 11 to 1n based on the servo system command from the robot control circuit 41.

In the control axis switching device 5, first, the decoder circuit 52 receives the axis switching signal from the axis switching signal generation circuit 44 and decodes the axis to be controlled. Based on the information, the motor power switching circuit 51 performs switching so that the motor power supplied from the servo amplifier 43 via the motor power line 32 is supplied to the servo motor of the control target axis. Further, the selector circuit 53 includes servo motors 11 to 1
Upon receiving the position data from the n pulse coder, the position data of the servo motor to be controlled is selected and sent to the robot control circuit 4 via the position data line 33.

FIG. 2 is a block diagram showing an embodiment of the control shaft switching device. Here, a case of a 4-axis robot is shown as an example of the multi-axis robot. Therefore, in the drawing, it is assumed that the multi-axis robot 1 is equipped with 4
Two servomotors 11, 12, 13, 14 and pulse encoders 111, 121, 1 for position detection built in these servomotors 11, 12, 13, 14 respectively.
31, 141 are shown.

A shaft switching signal line 31 from the control device 4 is connected to the control shaft switching device 5. The axis switching signal line 31 is composed of two lines, and each is terminated by a receiver 54. The output of the receiver 54 is connected to the decoder circuit 52 and also to the selector circuit 53. Decoder circuit 52 and selector circuit 5
3 has a function of specifying the control axis to be controlled by the control device 4 according to the logical state of the two axis switching signal lines 31. A method of selecting one of the control axes of the multi-axis robot 1 with these two axis switching signal lines 31 will be described.

FIG. 3 is a diagram showing the correspondence between the logic state of the axis switching signal line and the control axis. According to this figure, when the axis switching signals A and B are in the logic state of (0,0), it means the first control axis, and when the signals A and B are in the logic state of (0,1), the second control axis. It means the control axis, and similarly, when the signals A and B are (1,0), it means the third control axis, and when the signals A and B are (1,1), it means the fourth control axis. In the example of FIG. 2, the servo motor 11 is associated as the first control axis, the servo motor 12 is as the second control axis, and the servo motor 1 is as the third control axis.
3 and the servo motor 14 as the fourth control axis.

The motor power switching circuit 51 of the control axis switching device 5 includes four relays 511, 512, 513, 514.
It is composed of. Each relay 511, 512, 513,
The exciting coil of 514 is connected to the output of the decoder circuit 52, and these relay contacts are normally open contacts, and the motor power line 32 from the servo amplifier 43 of the controller 4 is connected.
Is connected between each of the servomotors 11, 12, 13, and 14. Therefore, when the axis switching signal is, for example, a logic level (0,0), decoder circuit 52 sets the output terminal corresponding to the first control axis to the ground state. As a result, the relay 511 is brought into an excited state to close its relay contact, and the motor power from the servo amplifier 43 is transmitted only to the servo motor 11. in this way,
The motor power from the servo amplifier 43 is supplied to only one of the plurality of servo motors designated by the axis switching signal.

On the other hand, the axis position data at the time of axis control is acquired from the pulse coders 111, 121, 131, 141 built in the servo motors 11, 12, 13, 14.
The signal output of each pulse coder 111, 121, 131, 141 is input to the selector circuit 53, where the position data from the pulse coder corresponding to one control axis designated by the axis switching signal is selected and the position data is output through the driver 55. One of the lines 33 is sent out to the line 331. The other line 332 is a line for transmitting a request signal for instructing a position data acquisition request from the robot control circuit 41 to the pulse coder. The request signal line 332 is connected to the receiver 56.
The output of the receiver 56 is terminated by the driver 57 for each pulse coder 111, 121, 131, 141.
Has been entered in. Therefore, when the position data acquisition request signal is transmitted from the control device 4, all the pulse coders 111, 121, 131, 141 output their position data in response to the request, but are actually returned to the control device 4. The position data is only position data relating to the control axis designated by the axis switching signal.

FIG. 4 is a diagram showing an embodiment of the brake circuit of the control shaft switching device. In this figure, the control axis switching device 5 has a brake circuit composed of relays 581, 582, 583, 584. These relays 581,
The exciting coils of 582, 583, and 584 are connected to the control device 4
, A brake control signal line 34 for a brake control signal sent independently from other signal lines via an input / output control circuit is connected. Each relay 581, 582, 5
The relay contacts 83 and 584 are connected between the brake power supply and the mechanical brakes (not shown) provided in the servomotors 11, 12, 13, and 14.

For example, when the control device 4 outputs an axis switching signal for controlling the first control axis, the servo motor 11 corresponding to this signal is the control target.
It is necessary to release the brake of the servo motor 11. At this time, a brake control signal is sent from the control device 4 via the brake control signal line 341. Then, the relay 581 is excited, the relay contact is closed, the brake power is supplied to the mechanical brake of the servomotor 11, and the brake is released. On the other hand, the brake power is not supplied to the mechanical brakes of the other servomotors 12, 13 and 14, and the brakes are maintained.

In this way, the servomotor for the axis that is not the control target is braked in order to maintain its operating position. In this embodiment, in order to determine the axis to be controlled, the brake control signal line 34 for controlling the brake circuit is independently wired without using the axis switching signal. This is because the control of the servomotors 11, 12, 13, and 14 is exclusive control of any one of these, but it is not related to the brake. That is, when switching the control axes, the servomotors 11, 12,
Regarding 13 and 14, the control of one servo motor is completely finished and then the control of another servo motor is started. At this time, the operation of the servo motor previously controlled at the time when the control is finished or immediately before the control is finished. The brake must be applied to hold the position, while the servo motor to be controlled next releases the brake after confirming that the previously controlled servo motor is completely braked. Therefore, when the control axes are switched, there is a time when the brake controls of the two servo motors overlap. Therefore, the brake control signal line 34 is installed independently of other signal lines.

In the above embodiment, the relay is used for switching between the motor power and the brake power source, but an electromagnetic contactor, a power transistor, a thyristor, a triac or the like can be used instead. Further, although two axis switching signals are used to select one of the four axes, this number is selected according to the number of control axes. If the number of control axes is large, the axis switching signals can be multiplexed and sent to the control axis switching device.

[0021]

As described above, according to the present invention, the control device has the control circuit for only one axis, and the multi-axis robot has the control axis switching device so that the control axes of the multi-axis robot can be controlled. By controlling each axis while switching,
For multi-axis robots that do not need to operate or position at high speed and need to control multiple axes at the same time, the control circuit and the connecting cable between the control device and the robot need only be one axis, low cost and reduced wiring. It is possible to realize a robot control method of optimization.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a robot control system of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of a control axis switching device.

FIG. 3 is a diagram showing a correspondence relationship between a logical state of an axis switching signal line and a control axis.

FIG. 4 is a diagram showing an embodiment of a brake circuit of the control axis switching device.

FIG. 5 is a diagram showing a schematic configuration of a conventional robot control system.

[Explanation of symbols]

 1 Multi-Axis Robot 4 Control Device 5 Control Axis Switching Device 11 to 1n Servo Motor 31 Axis Switching Signal Line 32 Motor Power Line 33 Position Data Signal Line 41 Robot Control Circuit 42 Axis Control Circuit 43 Servo Amplifier 44 Axis Switching Signal Generation Circuit 51 Motor Power switching circuit 52 Decoder circuit 53 Selector circuit 54,56 Receiver 55,57 Driver 511-514, 581-584 Relay

Claims (6)

[Claims] 1. A robot control method for controlling a multi-axis robot having a plurality of control axes which are not simultaneously controlled, and a control device having an axis control circuit for one axis and a servo amplifier, and the multi-axis robot installed on the multi-axis robot. , A control for connecting to the control device by a connection cable composed of a signal line for one axis, and switching the output of the servo amplifier to one of a plurality of servomotors selected based on a command from the control device. A robot control method comprising: an axis switching device. 2. The control device has a robot control circuit including an axis switching signal generation circuit for generating an axis switching signal representing a control axis to be controlled and instructing the control axis switching device. The robot control method according to item 1. 3. The robot control system according to claim 1, wherein the control axis switching device is built in the multi-axis robot. 4. The control axis switching device receives a axis switching signal from an axis switching signal generation circuit of the control device to decode a corresponding control axis, and a decoder circuit according to an output signal from the decoder circuit. 2. The robot control system according to claim 1, further comprising a motor power switching circuit for switching the motor power supplied from the servo amplifier to be supplied to the servo motor of the corresponding control axis. 5. The control axis switching device receives an axis switching signal from an axis switching signal generation circuit of the control device, selects position data from a pulse coder of a corresponding control axis, and selects a robot control circuit of the control device. 2. The robot control system according to claim 1, further comprising a selector circuit for sending to a robot. 6. The robot control system according to claim 1, wherein the control axis switching device has a brake circuit that supplies a brake power supply to the servo motor that is not controlled.