JP2020001137A - Robot control device and robot system - Google Patents

Abstract

To obtain a robot control device that can prevent a site other than a hand of a robot arm from entering an operation restriction area during teaching work.SOLUTION: A robot control device according to the invention comprises: a position command correction part that when a hand of a robot arm enters an operation restriction under a position command, corrects the position command by reducing components in a direction of the operation restriction area of the position command; an inverse kinematics calculation part that calculates angle patterns of each joint shaft that the robot arm has from the corrected position command; and an angle pattern selection part that selects an angle pattern of each joint shaft in which the robot arm does not enter the operation restriction area, of the angle patterns of each joint shaft calculated by the inverse kinematics calculation part. This can prevent a site other than the hand of the robot arm from entering the operation restriction area during teaching work.SELECTED DRAWING: Figure 1

Description

The present invention relates to a robot control device and a robot system that avoid operating range limitation in direct teaching of a robot arm whose operating range is limited.

Conventionally, a teaching operation has been performed in order for the robot arm to recognize the motion trajectory of the robot arm. The teaching operation is a process of storing the position where the hand of the robot arm to be used in the control program is to be moved in the robot arm before the operation of the robot arm by the control program. There is teaching. The direct teaching is a method of teaching by manually grasping and manually operating a robot arm and moving the robot arm to a position to be stored. In direct teaching, when a person directly grasps and moves the robot arm, the force generated in the robot arm is detected by the motor current value of each joint axis, torque sensor, etc., and the detected force is applied to the robot arm every moment. Directives can be created. In order to specify the position of the movement destination, the operator can manually operate the robot arm to move the hand of the robot arm to the position of the movement destination, so that the position of the movement destination can be stored in the robot arm.

In the robot arm capable of direct teaching as described above, if the robot arm does not want to touch an obstacle or the like in the operating environment during the direct teaching, the area of the target object is set as the operation limited area, 2. Description of the Related Art There has been conventionally known a technique of correcting or stopping the operation of a robot arm so that the robot arm does not enter an operation restriction area so that the robot arm does not contact an obstacle.

For example, in Patent Literature 1, when a force is applied to the tip of the robot arm during a teaching operation, if the tip is away from the operation restriction area, the applied force information is converted into the tip position of the movement destination, and then the tip is moved. The angle of each joint axis is calculated from the position by inverse kinematics, and the robot arm is driven by driving the motor based on the calculated angle of each joint axis. However, when the hand approaches the movement-limited area, the robot arm is driven in the same manner as above using the corrected force information after correcting to reduce the component of the force information applied to the hand in the direction of the movement-limited area. I do. Thus, as the hand approaches the motion restricted area, the force in the direction of the motion restricted area is ignored, so that it is possible to prevent the hand of the robot arm from entering the motion restricted area during the teaching operation.

JP 2005-34991 A

However, the robot controller as disclosed in Patent Document 1 corrects the force applied to the hand and corrects only the position of the hand, so that a part other than the hand of the robot arm that operates according to the movement of the hand is restricted in operation. It was not possible to prevent it from entering the area.

The present invention has been made in view of the above, and it is an object of the present invention to obtain a robot control device in which a part other than a hand of a robot arm does not enter a motion restricted area during a teaching operation.

The robot control device of the present invention includes an external operation force detection unit that detects an external operation force applied to the tip of the robot arm, an operation restriction region storage unit that stores an operation restriction region that is a region where the robot arm does not enter, A position command generation unit that generates a position command that indicates the position of the hand's movement destination from information on the external operation force detected by the external operation force detection unit, and a position command when the hand enters the operation restricted area by the position command. A position command correction unit that corrects the position command by reducing the component in the direction of the operation restriction area, an inverse kinematics calculation unit that calculates the angle pattern of each joint axis of the robot arm from the corrected position command, and an inverse motion. Pattern selection unit that selects an angle pattern of each joint axis that does not cause the robot arm to enter the operation restriction area from among the angle patterns of each joint axis calculated by the logical calculation unit , Comprising a.

According to the robot control device and the robot system according to the present invention, when the tip of the robot arm enters the operation restriction area due to the position instruction, the position instruction is generated by reducing the component of the position instruction in the operation restriction area direction and generating a corrected position instruction. A position command correction unit, an inverse kinematics calculation unit that calculates an angle pattern of each joint axis of the robot arm from the corrected position command, and a robot among the joint axis angle patterns calculated by the inverse kinematics calculation unit. Since there is provided an angle pattern selection unit for selecting an angle pattern of each joint axis in which the arm does not enter the operation restriction area, a robot control device and a robot for preventing a part other than the hand of the robot arm from entering the operation restriction area during a teaching operation You can get the system.

Schematic diagram of a robot system including the robot control device according to the first embodiment of the present invention. 4 is a flowchart illustrating the operation of the robot control device according to the first embodiment of the present invention. Schematic diagram of the correction processing according to the first embodiment of the present invention. Explanatory drawing of the correction processing of Embodiment 1 of the present invention. Schematic diagram of a robot system including the robot control device according to the first embodiment of the present invention.

Embodiment 1
Hereinafter, the robot control device according to the first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a robot system including the robot control device according to the first embodiment of the present invention. The robot system according to the first embodiment of the present invention includes a robot arm 1 and a robot control device 3.

The robot arm 1 includes a sensor 2 that can detect the magnitude of a force applied from the outside to the hand of the robot arm 1. The device capable of detecting the magnitude of the force is not limited to the torque sensor or the force sensor, but may be the current value of each joint shaft motor.

The robot control device 3 includes an external operation force detection unit 4, a position command generation unit 5, an operation restriction area storage unit 6, a position command correction unit 7, an inverse kinematics calculation unit 8, and an angle pattern selection unit 9.

The external operation force detection unit 4 detects the external operation force applied to the hand of the robot arm 1 from the force information acquired from the sensor 2 of the robot arm 1.

The position command generation unit 5 generates a position command that indicates the position of the hand of the robot arm 1 based on the external operation force information transmitted from the external operation force detection unit 4.

The operation restriction area storage unit 6 stores the operation restriction area 10 specified by the three-dimensional position coordinate system. The operation restriction area is an area in which the robot arm 1 is prohibited from entering, and for example, indicates an area where a person exists.

When the hand of the robot arm 1 approaches the operation restriction area 10 according to the position instruction generated by the position instruction generation section 5, the position instruction correction section 7 converts the component of the position instruction in the boundary normal direction of the operation restriction area 10. The position command of the moving destination of the hand is corrected by decreasing the distance.

The inverse kinematics calculation unit 8 calculates the angle pattern of each joint axis of the robot arm 1 for setting the hand at the position from the position command of the movement destination of the hand corrected by the position command correction unit 7. There are a plurality of combinations of angles of the joint axes in order to set the hand at a certain position, and the angle pattern refers to a combination of angles of the joint axes that realizes the certain position of the hand. In the description of the present invention, it is assumed that the robot arm 1 has a plurality of indirect axes. However, the present invention is not limited to this, and the robot arm 1 may have one indirect axis.

The angle pattern selection unit 9 calculates the angles of the joint axes at which the robot arm 1 does not intrude into the operation restriction area 10 stored in the operation restriction area storage unit 6 among the angle patterns of the joint axes calculated by the inverse kinematics calculation unit 8. A pattern is selected, converted into rotation command information for the motor of each joint axis, and transmitted to the robot arm 1. Note that the angle pattern selection unit 9 selects the angle pattern of each joint axis that does not cause the robot arm 1 to enter the operation restriction area 10. However, when there are a plurality of selectable angle pattern candidates, What is necessary is to select a pattern in which the change from the angle of each joint axis at that time is the smallest. As described above, by selecting the minimum pattern, the robot arm 1 can be moved to the target hand position in a shorter time and with less movement, so that the efficiency of the teaching work operation is improved and the operation of the robot arm 1 is improved. The vibration caused by the vibration can be reduced.

Next, an operation of the robot control device 3 of the first embodiment, particularly an operation during a teaching operation will be described. FIG. 2 is a control flow of the robot control device 3 during the teaching operation according to the first embodiment.

Before starting the teaching operation, the robot system builder sets the operation restriction area 10 of the robot arm 1. The information on the operation restriction area 10 is defined in a three-dimensional position coordinate system in the robot controller 3 and stored in the operation restriction area storage unit 6 of the robot controller 3. As a method of defining the motion restricted area 10, a method of designating three points in a three-dimensional space to divide the area using an infinite plane in the three-dimensional space, or setting a three-dimensional polyhedron area using a plurality of planes There are ways to do that. The method of setting the operation restriction area 10 is, for example, a method of directly inputting numerical information of position information necessary for expressing the operation restriction area 10, a method of operating the robot arm 1 at a corresponding position, and setting the hand position information of the robot arm 1 by using the method. There is.

After setting the operation restriction area 10, the robot control device 3 starts the control flow of FIG. First, in step S1, the external operation force detection unit 4 determines whether or not a force has been applied to the robot arm 1 by an operator. When the external operation force detection unit 4 does not detect the external operation force, the flow ends, and the process returns to step S1 to repeat the detection of the external operation force.

When the external operation force detection unit 4 detects the external operation force, the process proceeds to step S2, where the external operation force detection unit 4 converts the information of the external operation force acquired from the robot arm 1 into the external operation force information, and generates a position command. The position command generation unit 5 generates a position command. As the external operation force information, vector information of a force applied to the tip of the robot arm 1, torque information of each joint axis of the robot arm 1, a deviation between a commanded position of each joint axis of the robot arm 1 and an actual position, and the like can be considered. . The position command generator 5 creates a position command for the hand of the robot arm 1 based on the external operation force information. The position command created here is not limited to the hand position of the robot arm 1, and each of the robot arms 1 calculated by the forward kinematics calculation from the mechanism information of the robot arm 1 based on the joint angle of the robot arm 1 and its information. Location information of a part may be used.

After step S2, the process proceeds to step S3, where the position command correction unit 7 uses the position command generated by the position command generation unit 5 based on the information on the operation restriction area 10 stored in the operation restriction area storage unit 6 to control the robot arm. It is determined whether or not 1 enters the operation restriction area 10. As an example of the determination processing, when the operation restriction area 10 is defined as the front side of the plane in the three-dimensional coordinate system in the robot control device, one point to be restricted by the robot arm 1 in the position command is on the front side of the plane. In this case, it is determined that the user has entered the operation restriction area 10.

If it is determined in step S3 that the hand of the robot arm 1 enters the operation restricted area 10 with the position command as it is by the position command correction unit 7, the process proceeds to step S4, where the position command correction unit 7 executes the position command correction process. After the execution, the corrected position command is transmitted to the inverse kinematics calculation unit 8, and the process proceeds to step S5. If it is determined by the position command correction unit 7 that the hand of the robot arm 1 has not entered the operation restricted area 10, the correction processing in step S4 is not performed, and the position command correction unit 7 directly performs the inverse kinematics calculation unit. 8 and a step S5 is performed.

In step S5, the inverse kinematics calculation unit 8 calculates the angle pattern of each joint axis of the robot arm 1 from the position command from the position command correction unit 7, and the angle pattern selection unit 9 calculates the angle pattern by the inverse kinematics calculation unit 8. The robot arm 1 selects an angle pattern of each joint axis that does not enter the operation restriction area stored in the operation restriction area storage unit 6 and converts the angle pattern into an angle pattern of each joint axis. The robot arm 1 operates by transmitting a position command to the servomotor of each joint axis of the robot arm 1.

The robot control device 3 controls the robot arm 1 by the operations in steps S1 to S5 as described above.

Next, a method of correction by the position command correction unit 7 according to the first embodiment of the present invention will be specifically described.
FIG. 3 is a schematic diagram of the correction processing according to the first embodiment of the present invention. Here, it is assumed that the side on which the robot arm 1 does not exist is set as the operation restriction area 10 on the three-dimensional plane, and a force is applied only to the tip of the robot arm 1 by the hand 11 of the external worker. P _O is the actual hand position of the robot arm 1 calculated from the rotation angle of each joint axis obtained from the motor encoder of the robot arm 1, P _d is the position command output by the position command generation unit 5, and P _mod is the position command. 7 shows a position command corrected by the correction unit.

FIG. 4 is an explanatory diagram of a position command correction process performed by the position command correction unit 7 in step S4. X _d is a component that has entered the operation restricted area 10 of the position command, and a line segment connecting the tip unit position of the current robot arm 1 P _O and the position command P _d, a plan that defines the behavior restricted area 10 of the when the intersection was defined as P _C, the position vector from the P _C to the P _d is the X _d. By using the preset correction coefficient α (α ≧ 1), the corrected position command is calculated by the following equation (1).

（１）
によって算出される。

(1)
It is calculated by

The flow of processing in the actual position command correction unit 7 will be described. In the example of FIG. 3, since the position command _Pd has entered the operation restriction area 10, the position command correction unit 7 corrects the position command in step S < _b > 4 so that the position command Pd is outside the operation restriction area 10. It is necessary to correct to P _mod .

Therefore, first, as shown in FIG. 4, the current hand position P _O of the robot arm 1 calculated from the rotation angle of each joint axis obtained from the motor encoder of each joint axis of the robot arm 1 and the position command generation unit 5 output the current. calculating the intersection P _C between the plane defining the operation restriction area 10 stored and operated in the restricted area storage unit 6 line segment connecting P _d. Calculates the vector X _d connecting the next calculated P _C and the position command P _d, decomposed into the vector X _t on vector X _n a plane perpendicular to the plane that defines the behavior restricted area 10 the X _d . A corrected position command P _mod is calculated from the calculated X _n and a preset correction coefficient α using the above equation (1). The example of FIG. 4 is a case where the calculation is performed with α = 1.

The position command correction unit 7 outputs the corrected position command P _mod calculated as described above to the inverse kinematics calculation unit 8. The inverse kinematics calculation unit 8 calculates the angle pattern of each joint axis of the robot arm 1 from the position command, and the angle pattern selection unit 9 selects the angle pattern of each joint axis calculated by the inverse kinematics calculation unit 8. The robot arm 1 selects an angle pattern of each joint axis that does not enter the operation restriction area stored in the operation restriction area storage unit 6, and transmits a position command converted into the angle pattern of each joint axis to each joint axis of the robot arm 1. Send to servo motor.

As described above, the angle pattern selecting unit 9 transmits the position command converted into the angle pattern of each joint axis to the servomotor of each joint axis of the robot arm 1, and the control is performed in the same manner as the normal position control. .

Incidentally, as shown in FIG. 3, the position command P _d has entered the operation limit region 10, as the position command P _d in the hand of the robot arm 1 in step S3 enters the operation restriction area 10 and the position instruction correction When the determination is made by the unit 7, in step S4, the position command correction unit 7 performs the correction process of the position command, transmits the corrected position command to the inverse kinematics calculation unit 8, and simultaneously restricts the operation to the robot arm 1. It is also possible to generate an alarm indicating a factor that enters the area 10 and continue the teaching operation without stopping the operation. In that case, as shown in FIG. 5, an alarm generating unit 12 is provided in the robot controller 3. In this case, in step S4, the position command correction unit 7 performs the position command correction process, and simultaneously determines whether the hand of the robot arm 1 enters the operation restriction area 10 from the position command correction unit 7 to the alarm generation unit 12. The result of the judgment is given. When receiving a result of the determination that the hand of the robot arm 1 enters the operation restriction area 10, the alarm generation unit 12 generates an alarm indicating a factor of entering the operation restriction area 10.

Or has entered the position command P _d is the operation restriction area 10, is determined by the position command correction unit 7 and the same position command P _d in the hand of the robot arm 1 enters the operation restriction area 10 in step S3 At this time, the operation of the robot arm may be stopped until the operator applies a force so as not to enter the operation restricted area 10.

The above is the method of correcting the position command of the robot control device 3. As a result, even if an external operation force is applied to the robot arm 1 such that the robot arm 1 enters the operation restricted area 10, the command component for moving into the operation restricted area 10 is canceled, so that the robot arm 1 enters the operation restricted area 10. However, the teaching operation can be continued along the operation restriction area 10. Thus, the teaching operation can be smoothly performed in the vicinity of the operation restriction area 10 without entering the operation restriction area 10 and stopping the robot arm 1.

The operator completes the teaching work when the robot arm 1 can recognize the target teaching position by the direct teaching operation.

As described above, according to the robot control device 3 and the robot system of the present invention, when the robot arm 1 enters the operation restriction area 10 by the position command generated based on the external operation force information, the position command A position command correction unit for generating a corrected position command by reducing a component in a direction normal to the boundary surface of the operation restriction area; calculating an angle pattern of each joint axis of the robot arm from the corrected position command; Inverse kinematics calculation unit 8 and an angle pattern for selecting an angle pattern of each joint axis from which the robot arm 1 does not enter the operation restriction area 10 among the angle patterns of each joint axis calculated by the inverse kinematics calculation unit 8 Since the selection unit 9 is provided, it is possible to prevent the hand position of the robot arm 1 and a part other than the hand position from entering the operation restriction area 10 during the teaching operation. It is possible.

DESCRIPTION OF SYMBOLS 1 Robot arm 2 Sensor 3 Robot controller 4 External operation force detection part 5 Position command generation part 6 Operation restriction area storage part 7 Position command correction part 8 Inverse kinematics calculation part 9 Angle pattern selection part 10 Operation restriction area 11 Hand 12 Alarm Generator

Claims (5)

An external operation force detection unit that detects an external operation force applied to the hand of the robot arm,
An operation restriction area storage unit that stores an operation restriction area that is an area where the robot arm does not enter,
From the information of the external operation force detected by the external operation force detection unit, a position command generation unit that generates a position command that indicates the position of the destination of the hand,
When the hand enters the operation restriction area by the position command, a position command correction unit that corrects the position command by reducing a component in the direction of the operation restriction area of the position command,
An inverse kinematics calculation unit that calculates an angle pattern of each joint axis of the robot arm from the corrected position command;
A robot pattern control unit comprising: an angle pattern selection unit that selects an angle pattern of each joint axis in which the robot arm does not intrude into the operation restriction area from among the angle patterns of each joint axis calculated by the inverse kinematics calculation unit. apparatus. The angle pattern selection unit, when there are a plurality of angle patterns of the respective joint axes in which the robot arm does not enter the operation restriction area, selects the angle pattern with the smallest change in the angle of each joint axis. The robot control device according to claim 1, wherein: Further comprising an alarm generating unit that generates an alarm indicating a factor that enters the operation restriction area,
Even if the position command correction unit determines that the position command generated by the position command generation unit enters the operation restriction area, the position command correction unit notifies the alarm generation unit of information of the determination result and corrects the position command. The robot control device according to claim 1, wherein the operation of the robot arm is continued as a result. Said robot arm,
A sensor installed on the robot arm for detecting the external operation force and transmitting the external operation force to the external operation force detection unit;
A robot system comprising: the robot control device according to claim 1. Said robot arm,
A sensor installed on the robot arm for detecting the external operation force and transmitting the external operation force to the external operation force detection unit;
A robot system comprising: the robot control device according to claim 3.

Images