JP3327205B2 - Robot control method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling an industrial robot having a plurality of joint axes when a collision with an external object occurs.

[0002]

2. Description of the Related Art Conventionally, a collision detection process is performed to prevent a mechanical part of an industrial robot driven by a servo motor from being damaged by a collision with an obstacle or a work.
Then, in the collision detection, a disturbance torque generated in the servomotor when the mechanism unit collides is estimated by a disturbance estimation observer, and when the estimated disturbance torque exceeds a set threshold value, it is determined that a collision has occurred. I do. However, since the disturbance torque generated when the robot collides includes the frictional force of the machine, the reaction force of the spring system, and the gravitational force applied to the machine, as described in JP-A-3-196313, the collision determination is performed. Is set to a value larger than the above-described frictional force, reaction force, and gravity and smaller than the withstand strength of the mechanism.

[0003]

However, in the above-mentioned prior art example, how to stop the robot after the collision determination is not considered.

[0004] Therefore, there is a problem that it is impossible to prevent the generation of the contact force generated after the collision.

Further, in the case of a robot having a welding torch, there has been a problem that no operation has been studied for realizing an operation for preventing erroneous welding when a collision occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control method and a control device of a robot for performing a stop process of the robot after a collision is determined.

[0007]

[0008]

Means for Solving the Problems To achieve the above object,
In a first method of the present invention, a robot having a plurality of joint axes consisting of a basic axis for determining the position of the robot tip and a wrist axis for determining the posture of the robot tip detects a collision at a certain joint axis. Then, a relief operation is performed on the joint axis that has detected the collision, the basic axis is stopped as the other joint axis, the wrist axis is maintained movably with respect to the external force, and after a first predetermined time, all the joint axes are Is mechanically restrained.

Further, according to a second method of the present invention, after mechanically constraining all the joint axes, the power of each motor for driving the joint axes is cut off after a lapse of a second predetermined time. Stop the operation of the servo unit.

[0010]

Further, the third method of the present invention defines the time for performing the relief operation of the joint axis that has detected the collision, the distance moved by the relief operation, or both.

[0012]

[0013]

Further, according to a first configuration of the present invention, a joint axis of a robot having a plurality of joint axes including a basic axis for determining the position of the robot tip and a wrist axis for determining the posture of the robot tip detects a collision. Then, a relief operation is performed on the joint axis that has detected the collision, the basic axis of the other joint axes is stopped, and the wrist axis is maintained movably against external force,
A control unit that controls to mechanically constrain all joint axes after a first predetermined time;

Further, according to a second configuration of the present invention, after mechanically constraining all the joint axes, the power supply of each motor for driving the joint axes is cut off after a lapse of a second predetermined time. Has a control unit for stopping the operation of the servo unit.

[0016]

Further, the third configuration of the present invention has a control unit that defines the time for performing the relief operation of the joint axis that has detected the collision, the distance moved by the relief operation, or both.

[0018]

[0019]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first structure of the present invention and the first
According to the method, when a robot having a plurality of joint axes consisting of a basic axis for determining the position of the robot tip and a wrist axis for determining the posture of the robot tip detects a collision with a certain joint axis, the collision is detected. By making the joint axis perform a relief operation, the impact force due to the collision is reduced, the basic axis is stopped as the other joint axis, and the wrist axis is kept movable against external force, so that further collision and excessive By preventing the generation of contact force and mechanically constraining all joint axes after the first predetermined time, the robot can be completely stopped.

Furthermore, according to the second configuration and the second method of the present invention, after mechanically constrained all joint axes, the power to each motor for driving the joint shaft after the second predetermined time Because of the interruption, the robot can be completely stopped.

[0022]

Furthermore, according to the third configuration and the third method of the present invention, or time for the relief operation of the joint axis a collision is detected, or distance traveled by the relief operation, defining both of them Thus, it is possible to prevent the collision from occurring again due to the escape operation being too large.

[0024]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an industrial robot having six joints to which the robot control method and control device of the present invention are applied. In the figure, A1 to A6 represent joint axes, A1 to A3 are basic axes that determine the position of the robot tip, and A4 to A6 are wrist axes that determine the posture of the robot tip. Attach a tool such as a welding torch before the wrist axis to perform various tasks.

[0026] (Reference Example 1) is first described in Reference Example 1 of the present invention. FIG. 2 shows A1
FIG. 10 is an explanatory diagram of a process when a robot having N joint axes from to to AN has caused a collision. Here, Ak represents the k-th joint axis. Now, assume that the robot collides with an external object and detects the collision at the k-th joint axis. At this time, in the control method of this robot, FIG. 2
As shown in (b), first, in step S1, the axis Ak that has detected a collision is stopped. Next, in step S2, the (k-1) th joint axis Ak-1 and the (k + 1) th joint axis Ak + 1 are stopped. In the same manner, the processing is executed until all the axes stop.

[0027] FIG. 3 is a block diagram showing a configuration example of a control device of the robot this. In the figure, 100 is a control unit, 1 is an axis control unit, 11 is a servo unit, 12 is a motor,
13 is a collision detection unit. If there are N joint axes, there is one axis control unit for each joint axis. k
Represents an axis control unit for the k-th joint axis.

The interrelationship and operation of the above components will be described. The control unit 100 transmits an operation command and a stop command from the axis control unit 1 to N. Axis control unit 1 to N in N
The servo units 1 to N1 receive operation commands from the control unit,
N2 is controlled from the motor 12. The collision detectors 13 to N3 receive signals from the servo units 11 to N1 to detect whether or not the robot has collided.
Sends a collision detection signal to The control unit 100 that has received the collision detection signal transmits a stop command to each of the joint axes from the axis control unit 1 to N in accordance with the processing content described with reference to FIG.
The axis control unit that has received the stop command immediately stops the operation.

[0029] (Embodiment 1) Next, a control method for a robot according to the first method, the
An embodiment of the robot control device having the configuration 1 will be described.

FIG. 4 is an explanatory diagram of processing when a robot having six joint axes A1 to A6 has a collision. Now, in FIG. 4A, it is assumed that the robot collides with an external object, and the collision is detected by the joint axis A5. At this time, in the robot control method described in the first method, as shown in FIG. 4B, first, in step S101, the axis where the collision is detected so that the collision point of the robot is separated from the colliding external object. A5 is caused to perform the escape operation. Next, in step S102, the basic axes A1, A
2. Stop A3. Next, in step S103, the wrist axes A4 and A6 are set movably with respect to external force. Next, in step S104, step S103
After a first predetermined time has elapsed after the execution of the above, all the joint axes are mechanically restrained.

FIG. 5 is a block diagram showing an example of the configuration of a control device for a robot having the first configuration. In the figure, 101 is a control unit, 1 is an axis control unit, 11 is a servo unit, 12 is a motor, 13 is a collision detection unit, and 14 is a mechanical restraining unit. If there are six joint axes, there is one axis control unit for each joint axis. k represents the axis control unit of the k-th joint axis.

The interrelationship and operation of the above components will be described. The control unit 101 transmits an operation command and a stop command to the axis control units 1 to 6. 1 of axis control units 1 to 6
The servo units 1 to 61 receive operation commands from the control unit,
The motors 12 to 62 are controlled. The collision detection units 13 to 63 receive signals from the servo units 11 to 1, detect whether the robot has collided, and transmit a collision detection signal to the control unit 101. In response to the collision detection signal, the control unit 101 sends an operation command and a stop command to the axis control units 1 to 6 of the respective joint axes according to the processing described in FIG. In response, a command to execute mechanical restraint is transmitted. In mechanical restraints 14 to 64,
When a command to execute mechanical restraint is received from the control unit 101, each joint axis is mechanically restrained.

[0033] (Embodiment 2) Next, a control method for a robot according to the second method, the
An embodiment of the robot control device having the two configurations will be described.

FIG. 6 is an explanatory diagram of processing when a robot having six joint axes A1 to A6 has a collision. In the figure, steps S101, S102, S10
3. Steps S104 are the same as the steps described with reference to FIG. Now, it is assumed that the robot collides with an external object, and the collision is detected by the joint axis A5. At this time, in the robot control method according to the second method, the processes from step S101 to step S104 are executed as described with reference to FIG.

Next, in step S105, after the execution of step S104, the power of each motor for driving the joint shaft is cut off after a lapse of the second predetermined time, and the operation of the servo unit for controlling the motors is stopped.

An example of the configuration of the control device for the robot having the second configuration is the same as the block diagram described with reference to FIG.
01 is different. The control unit 101 transmits an operation command and a stop command from the axis control unit 2 to N. The servo units 11 to N1 in the axis control unit 1 to N receive operation commands from the control unit and control the motor 12 from N2.
The collision detection units 13 to N3 receive signals from the servo units 11 to N1 to detect whether the robot has collided, and transmit a collision detection signal to the control unit 101. Upon receiving the collision detection signal, the control unit 101 transmits an operation command, a stop command, and a power cutoff command to the axis control units 1 to 6 of the respective joint axes according to the processing described in FIG. To 64 are transmitted. When receiving the execution command of the mechanical constraint from the control unit 101, the mechanical constraint units 14 to 64 mechanically constraint each joint axis. The axis control units 1 to 6 of the joint axes that have received the power cutoff command cut off the power of the motors that drive the joint axes and stop the operation of the servo unit that controls the motors.

REFERENCE EXAMPLE 2 Next, a robot control method and a robot control device will be described .
Reference Example 2 will be described.

The seventh is an explanatory diagram of a process when a robot having a welding torch 500 attached to the ends of six joint axes A1 to A6 and a wrist axis causes a collision.

Now, in FIG. 7A, it is assumed that the robot collides with an external object and that the collision is detected by a certain joint axis. At this time, in the robot control method described in the fourth method, as shown in FIG.
In step 1, each joint shaft is caused to perform an escape operation in a direction opposite to the torch vector direction 501 so that the tip of the torch is quickly separated from the welding work.

FIG. 8 is a block diagram showing a configuration example of a control device for a robot having a fourth configuration. In the figure, 201 is a control unit, 1 is an axis control unit, 11 is a servo unit, 12 is a motor, and 13 is a collision detection unit. If there are N joint axes, there is one axis control unit for each joint axis.
k represents the axis control unit of the k-th joint axis.

The interrelationship and operation of the above components will be described. The control unit 201 transmits an operation command or a stop command from the axis control unit 2 to N. Axis control unit 1 to N in N
The servo units 1 to N1 receive operation commands from the control unit,
N2 is controlled from the motor 12. The collision detectors 13 to N3 receive signals from the servo units 11 to N1 to detect whether or not the robot has collided.
Sends a collision detection signal to The control unit 201 that has received the collision detection signal transmits an operation command to N from the axis control unit 1 of each joint axis according to the processing described in FIG. 7B.

[0042] (Third Embodiment) Next, a control method for a robot according to a third method, the
An embodiment of the robot control device having the three configurations will be described.

As described with reference to FIGS. 4, 6, and 7,
When the robot collides with an external object, the robot performs an escape operation so that the robot separates from the colliding external object. When the escape operation is performed, the time for performing the escape operation, the distance moved by the escape operation, or both of them are defined.

FIG. 9 shows the processing contents. Before operating the robot, in step S301, a time for performing the escape operation or a distance to be moved by the escape operation is set. When executing step S101 in FIG. 4 and FIG. 6 or step S201 in FIG. 7, the robot performs an escape operation according to the specified value set here.

An example of the configuration of the robot controller having the fifth configuration is the same as the block diagram described with reference to FIGS. 5 and 8, but the processing described in FIG. The only difference is what is done.

Reference Example 3 Next, a third reference example will be described.

FIG. 10 is an explanatory diagram of a process when a collision occurs with the robot having the welding torch WT. In the figure, when a certain joint axis detects a collision, step S401 is performed.
In, the welding power supply for supplying power to the welding torch provided at the tip of the robot wrist is shut off. Next, in S402, the robot stop processing described in the first to fifth embodiments is executed.

FIG. 11 is a block diagram showing a configuration example of a control device for a robot according to a third reference example . In the figure, 30
Reference numeral 1 denotes a control unit, 1 denotes an axis control unit, 11 denotes a servo unit, 12 denotes a motor, 13 denotes a collision detection unit, and 400 denotes a welding power source. If there are N joint axes, there is one axis control unit for each joint axis. k represents the axis control unit of the k-th joint axis.

The interrelationship and operation of the above components will be described. The control unit 301 transmits an operation command and a stop command from the axis control unit 2 to N. Axis control unit 1 to N in N
The servo units 1 to N1 receive operation commands from the control unit,
N2 is controlled from the motor 12. The collision detection unit 13 to N3 receives a signal from the servo unit 11 to N1 to detect whether the robot has collided, and the control unit 30
1 transmits a collision detection signal. Upon receiving the collision detection signal, the control unit 301 first outputs a welding power supply shutoff command to the welding power supply 400 according to the processing described in FIG.
The robot stop processing described in the first to fifth embodiments is executed.

It goes without saying that each of the components in these six examples and their operations can be realized by a program operation of a microcomputer.

[0051]

[0052]

According to the first configuration and the first method of the present invention,
According to a robot having a plurality of joint axes consisting of a basic axis for determining the position of the robot tip and a wrist axis for determining the posture of the robot tip, when a collision is detected by a certain joint axis, the joint axis that detected the collision is detected. In order to reduce the impact force due to the collision by performing the escape operation, stop the basic axis as another joint axis and maintain the wrist axis freely movable against external force, further collision and excessive contact force Is prevented and the robot can be completely stopped by mechanically restraining all the joint axes after the first predetermined time.

[0053] Furthermore, according to the second configuration and the second method of the present invention, after mechanically constrained all joint axes, the power to each motor for driving the joint shaft after the second predetermined time Because of the interruption, the robot can be completely stopped.

[0054]

[0055] Further, according to the third configuration and the third method of the present invention, or time for the relief operation of the joint axis a collision is detected, or distance traveled by the relief operation, defining both of them Thus, it is possible to prevent the collision from occurring again due to the escape operation being too large.

[0056]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an industrial robot having six joints to which the present invention is applied.

FIG. 2 is an explanatory diagram of a process when a collision occurs with a robot having N joint axes according to the robot control method of Reference Example 1;

FIG. 3 is a block diagram showing the configuration of a control device of Reference Example 1 Robot

FIG. 4 is an explanatory diagram of processing when a robot having six joint axes has collided by the robot control method according to the first embodiment;

FIG. 5 is a block diagram illustrating a configuration of a control device for the robot according to the first embodiment;

FIG. 6 is an explanatory diagram of processing when a robot having six joint axes has collided by the robot control method according to the second embodiment;

FIG. 7 is an explanatory diagram of processing when a robot having a welding torch according to Reference Example 2 has caused a collision.

8 is a block diagram showing the configuration of a control device of Reference Example 2 Robot

FIG. 9 is an explanatory diagram of a process of a robot control method according to the third embodiment.

FIG. 10 is an explanatory diagram of processing when a robot having a welding torch in the reference example 3 causes a collision.

FIG. 11 is a block diagram illustrating a configuration of a robot control device according to a third embodiment;

[Explanation of symbols]

 A1 to AN joint axis 100 control unit 101 control unit 201 control unit 301 control unit 400 welding power source 1 to N-axis control unit 11 to N1 servo unit 12 to N2 motor 13 to N3 collision detection unit 14 to N4 mechanical constraint unit 500 welding Torch 501 Torch vector direction

──────────────────────────────────────────────────続 き Continuation of the front page (72) Takashi Nakatsuka, Inventor 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-3-281194 (JP, A) JP-A-62- 140795 (JP, A) JP-A-6-278082 (JP, A) JP-A-4-152091 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B25J 19/06 B23K 11 / 24 340 G05D 3/00

Claims (6)

(57) [Claims] 1. A robot having a plurality of joint axes consisting of a basic axis for determining the position of the robot tip and a wrist axis for determining the posture of the robot tip, the collision is detected when a collision is detected with a certain joint axis. Escape action on joint axis
And stop the basic axis as another joint axis,
The shaft is kept movable with respect to external force and after a first predetermined time
A robot control method , wherein all joint axes are mechanically constrained . 2. After mechanically constraining all joint axes,
2. Power supply for each motor that drives the joint axis after a predetermined time
And stop the operation of the servo unit for motor drive control
2. The method for controlling a robot according to claim 1, wherein: 3. The relief operation of the joint shaft that has detected the collision is performed.
Time, the distance traveled by the escape action, or both
The method of controlling a robot according to claim 1 or 2, wherein the method is defined . 4. A basic axis for determining a position of a robot tip,
Multiple functions consisting of wrist axes that determine the posture of the robot tip
Collision against each joint axis in a robot with a nodal axis
Collision detecting means for detecting a collision, and a joint detecting the collision
The axis performs the relief operation, and the basic axis is used as the other joint axis.
Stop and maintain the wrist axis movably against external force.
After one predetermined time, mechanically restrain all joint axes
A control device for a robot having a control unit for controlling the robot . 5. After mechanically constraining all joint axes,
2. Power supply for each motor that drives the joint axis after a predetermined time
And stop the operation of the servo unit for motor drive control
The control device for a robot according to claim 4 . 6. A relief operation of a joint shaft that detects a collision is performed.
Time, the distance traveled by the escape action, or both
6. The control device for a robot according to claim 4, wherein the direction of the robot is defined .