JP6354248B2 - Robot, robot system, control device, and control method - Google Patents

Description

  The present invention relates to a robot, a robot system, a control device, and a control method.

Conventionally, it has been proposed to cause a robot to perform work using tools. In such work, it has been proposed to directly connect an end effector to a robot arm (see, for example, Patent Document 1). In such work, a method for teaching an operation position to a robot has been proposed (see, for example, Patent Document 2). Further, in such work, it has been proposed to determine and coordinate the coordinates of a predetermined point based on the image of the work object (see, for example, Patent Document 3).

JP 2012-35391 A JP 2003-127078 A JP 2003-225837 A

However, conventionally, there have been cases where the accuracy of work by a robot holding a tool cannot be improved. When the robot performs a work while holding a tool, it is desirable to accurately derive the relative position and posture between the tool and the work target. However, in the derivation of the relative position, a large error may occur due to variations in manufacturing of the arm or hand, a shift in the posture of the tool due to a gripping state, a low rigidity of the arm, and the like. As a result, the robot sometimes fails to work using the grasped tool.

The present invention has been made in view of the above points, and an object of the present invention is to provide a robot, a robot system, a control device, and a control method that can improve the accuracy of work performed by a robot holding a tool.

The present invention has been made to solve the above problems, and an embodiment of the present invention is as follows.
A force sensor; a hand that grips a tool used for work; and a control unit that operates the hand, the control unit contacting the tool held by the hand with a work object. After determining the position or posture of the robot, the robot causes the hand to perform the operation.
With this configuration, the control unit determines the position or posture of the robot based on the contact between the tool, such as an assembly member, having a high accuracy in its shape and the tool. The relative position or posture can be accurately derived. Therefore, the robot can improve the accuracy of work. In addition, since this configuration does not require a robot-specific tool such as an end effector, it is possible to reduce the cost and time required for creating the robot-specific tool.

In one embodiment of the present invention, after the control unit determines the position or posture of the hand,
A robot that changes the position or posture of the hand based on a predetermined amount of change and causes the hand to perform the operation.
With this configuration, the control unit accurately moves the robot to the position where the work is performed based on the amount of change from the position or posture determined by contact with the work object, or moves the robot to a posture suitable for the work. Can be. Therefore, the robot can improve the accuracy of work.

In one embodiment of the present invention, the control unit causes the hand to grip the tool with a weak force before the contact, and determines the force that the hand grips when the position or posture of the hand is determined. It is a robot that strengthens and causes the hand to perform the work.
With this configuration, the control unit flexibly adjusts the position or posture of the tool with respect to the robot by contact, and after determining the position or posture, the control unit firmly grasps the tool to thereby determine the relative position and the tool of the tool with respect to the robot. Since the posture is fixed, the accuracy of the work can be improved.

Moreover, one Embodiment of this invention is a robot with which the said control part contacts the predetermined | prescribed site | part of the said tool which the said hand hold | grips with the said work target object.
With this configuration, the control unit controls the robot to bring a predetermined part of the tool into contact with the work target, so that the position of the tool action point and the tool posture can be determined more accurately. Therefore, the robot can improve the accuracy of work.

In addition, an embodiment of the present invention includes a robot including a force sensor, a hand that holds a tool used for work, and a control unit that operates the robot, the control unit serving as a work target The robot system is configured to cause the robot to perform the operation after determining the position or posture of the hand by contacting the tool held by the hand.
With this configuration, the control unit determines the position or posture of the robot based on the contact between the tool, such as an assembly member, having a high accuracy in its shape and the tool. The relative position or posture can be accurately derived. Therefore, the robot system can improve the accuracy of work.

Moreover, one embodiment of the present invention is a control device that operates a robot including a force sensor and a hand that holds a tool used for work, and makes the tool held by the hand contact a work object. After determining the position or posture of the hand, the control device causes the robot to perform the operation.
With this configuration, the control device determines the position or posture of the robot based on the contact between the work object having a high accuracy in its shape, such as an assembly member, and the tool, so that the relative position between the tool and the work object is determined. Alternatively, the posture can be accurately derived. Therefore, the control device can increase the accuracy of work by the robot.

An embodiment of the present invention is a control method for operating a robot including a force sensor and a hand that grips a tool used for work, wherein the tool gripped by the hand is brought into contact with a work target. And determining the position or posture of the hand and causing the robot to perform the operation.
By this method, since the position or posture of the robot is determined based on the contact between the tool such as an assembly member having a high accuracy in its shape and the tool, the relative position or posture of the tool and the work target is determined. Accurately derived. Therefore, the above-described control method can improve the accuracy of work.

As described above, according to the present invention, the robot, the robot system, the control device, and the control method can each increase the accuracy of the work performed by the robot holding the tool.

1 is a diagram illustrating an example of a schematic configuration of a robot system according to an embodiment of the present invention. It is a block diagram which shows an example of schematic function structure of the control apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the 1st example of the operation | work by the robot system which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the flow of the process which the control apparatus which concerns on one Embodiment of this invention performs. It is a figure for demonstrating an example of operation | movement of the robot system which concerns on one Embodiment of this invention. It is a figure for demonstrating the 2nd example of the operation | work by the robot system which concerns on one Embodiment of this invention. It is a flowchart which shows an example of the flow of the process which the control apparatus which concerns on one Embodiment of this invention performs. It is a figure for demonstrating an example of operation | movement of the robot system which concerns on one Embodiment of this invention. It is a figure which shows an example of the schematic structure of the robot system which concerns on another structural example.

Embodiments of the present invention will be described in detail with reference to the drawings.
[Robot system overview]
FIG. 1 is a diagram illustrating a schematic configuration example of a robot system 1 according to an embodiment of the present invention.
The robot system 1 according to this embodiment includes a robot 10, a control device 20, and an imaging unit 3.
0. The robot 10 includes a control device 20 therein. The imaging unit 30 and the control device 20 of the robot 10 are connected to be communicable via a line 40. In the present embodiment, the line 40 is wired, but may be wireless.

The robot system 1 is a system that performs work using tools held by a robot. In the present embodiment, the tool is made for human beings, for example. Specifically, the tool is, for example, an E-ring setter used for fitting an E-ring or a screwdriver used for screw fastening. In the following, as an example, the robot 10 holding the E-ring setter
A robot system comprising: Further, the robot system 1 hits the reference position in order to accurately specify the work position when performing the work using the tool.

Here, the work position is, for example, the position of a contact point in performing the work between the work object and the tool held by the robot 10 or a member held by the tool. What is the reference position?
It is a specific position on the surface of the work object, a position in the vicinity of the work position, and a position where the relative positional relationship from the work position is accurately determined. The position in the vicinity of the work position is close enough that even if the control device 20 moves the robot 10 between the reference position and the work position, an error that causes trouble in work accuracy due to the movement is not caused. Position. In the present embodiment, the work object is a member used for work, for example, and the robot 10 holding the tool is disposed at a position where the tool can be brought into contact. In the present embodiment, the hit is based on a detection result of an external force or a moment applied to the robot 10 by the contact of the control device 20 with the control unit 20 by bringing the predetermined part of the tool into contact with the reference position, for example. Thus, the operation of the robot 10 is stopped. The predetermined part of the tool is, for example, a part where the tool is easily brought into contact with the reference position, and is, for example, an end point such as a tip of the tool.

The robot 10 is, for example, a single-arm articulated robot including a manipulator 11 that constitutes one arm (arm). The manipulator 11 includes a hand (gripping part) 12 and a force (force sensor) 13 at the tip part. The manipulator 11 is a hand 1
2 and a drive unit (actuator) that drives the joint unit and the like, and operates based on a control signal acquired from the control device 20. The robot 10 can determine the position and posture based on a plurality of points on the hand 12 and the arm, and can change the position and posture of the tool. However, these control methods are well-known techniques, and thus description thereof is omitted.

The hand 12 includes a component that holds the tool, and includes, for example, two or more finger-shaped components. The gripping position and posture of the tool by the hand 12 are determined in advance for each tool, and the hand 12 grips a predetermined position of the tool so that the tool has a predetermined posture. In the present embodiment, the hand 12 holds a predetermined position of the handle portion so that the E-ring setter is in a predetermined posture. Thereby, the robot system 1 acquires the coordinates of the end points of the tool in the world coordinate system. However, an error may occur in the posture and position of the tool during gripping, and the position of the end point of the tool in the world coordinate system is not always exactly the same as the position in the real space. Since a known technique can be used for the process for gripping the predetermined position, details are omitted.

The force sensor 13 detects a force and a moment applied to the hand 12. Force sensor 13
Outputs haptic information indicating the detected force and moment to the control device 20. Force sensor 1
3 detects, for example, six components of a force component in the translational three-axis direction and a moment component around it simultaneously. Here, the three translational axes are, for example, three orthogonal to each other forming a three-dimensional orthogonal coordinate system.
These are two coordinate axes (X axis, Y axis, Z axis).

The imaging unit 30 includes a camera module and is installed in an arrangement capable of capturing an image including a tool held by the robot 10 and a work target. The imaging unit 30 images the tool and the work target at a predetermined time interval such as 30 [msec], for example. In addition, the imaging unit 30 includes a communication interface connected to the line 40. The imaging unit 30 transmits object image information that is information of the captured image to the control device 20 via the line 40.

The control device 20 controls the robot 10 by three types of control methods: visual servo, impedance control, and position and orientation control.
The visual servo is a control method for tracking a target by measuring a change in position relative to the target as visual information and using the measured visual information as feedback information. In the visual servo, the control device 20 compares the target image captured by the imaging unit 30 as needed with the target image, and performs visual feedback control so that the target image matches the target image. Here, the target image is an image obtained by the imaging unit 30 capturing a state where the target object is arranged at the target position and orientation. In the present embodiment, the object is, for example, a tool held by the hand 12.

Impedance control is control based on the output of the force sensor 13 provided in the robot 10. The control device 20 detects an external force applied to the robot 10 in the impedance control, and drives the actuator so that the displacement (stiffness), speed (viscosity), and inertia (acceleration) responses due to the external force have desired values. To control.

Position and orientation control is performed by designating a specific target coordinate as a coordinate of a point to be controlled in the world coordinate system recognized by the robot system 1, so that the robot 10 and the robot 10
This is a control method for controlling the position and orientation of an object held by the. In the position / orientation control of the present embodiment, the control device 20 controls the robot 10 so that, for example, the current coordinates of the tool end point coincide with the target coordinates. In the position and orientation control of the present embodiment, the control device 20 controls the robot 10 so that the tool end point passes through a line segment connecting the current coordinate of the tool end point and the target coordinate, for example.

[Outline of control device]
FIG. 3 is a block diagram illustrating an example of a schematic functional configuration of the control device 20.
The control device 20 is a control device that controls the operation of the robot 10, and a CPU is provided inside the device.
(Central Processing Unit) and a storage device. The control device 20 includes a storage unit 21, an input unit 22, an output unit 23, and a control unit 24.

The storage unit 21 includes, for example, an HDD (Hard Disc Drive), a flash memory, and an EEPROM (Electrically Erasable Program).
bable Read Only Memory), ROM (Read Only Memory)
ory) or RAM (Random Access Memory) or the like, and stores various programs to be executed by the CPU provided in the control device 20, results of processing executed by the CPU, and the like.

Moreover, the memory | storage part 21 performs various control, and memorize | stores the information for achieving an operation | work. For example, the storage unit 21 stores control switching conditions and switching order in work. Further, the storage unit 21 stores, for example, target image information that is information on a target image used for visual servoing. In addition, the storage unit 21 stores, for example, target coordinates of tool end points used for position and orientation control. In addition, the storage unit 21 stores, for example, target values of inertia, attenuation coefficient, and stiffness impedance used for impedance control. Part or all of the control unit 24 functions, for example, when a CPU included in the control device 20 executes a program stored in the storage unit 21. In addition, a part or all of the control unit 24 is an LSI (Large S).
call Integration) and ASIC (Application Speci)
It may be configured by hardware such as fic Integrated Circuit).

The input unit 22 receives input from the outside. The input unit 22 may include, for example, a keyboard and a mouse for receiving an operation input from a user of the robot system 1. In addition, the input unit 22 may include a function for receiving an input from an external device, for example, including a communication interface.
The output unit 23 outputs various information to the outside. The output unit 23 may include, for example, a display that outputs image information to the user. The output unit 23 is, for example,
You may provide the speaker etc. which output audio | voice information with respect to a user. The output unit 23 may include a communication interface and a function of outputting information to an external device, for example.

The control unit 24 includes a target image information acquisition unit 241, an object image information acquisition unit 242, a target coordinate acquisition unit 243, a sensor output acquisition unit 244, a visual servo unit 245, a position and orientation control unit 246, and an impedance. A control unit 247 and a control switching unit 248 are provided.

The target image information acquisition unit 241 reads target image information from the storage unit 21 and outputs the read target image information to the visual servo unit 245.
The object image information acquisition unit 242 acquires object image information indicating the object image from the imaging unit 30 via the line 40. The object image information acquisition unit 242 outputs the acquired object image information to the visual servo unit 245.

The target coordinate acquisition unit 243 reads target coordinate information for position and orientation control from the storage unit 21, and outputs the read target coordinate information to the position and orientation control unit 246.
The sensor output acquisition unit 244 acquires the force information output from the force sensor 13 via the line 40 and outputs the acquired force information to the impedance control unit 247.

The visual servo unit 245 controls the robot 10 by visual servoing based on the target image information acquired from the target image information acquisition unit 241 and the object image information acquired from the object image information acquisition unit 242. Generate a signal. Visual servo section 24
5 transmits the generated control signal to the robot 10.

The position / orientation control unit 246 acquires information indicating the target coordinates from the target coordinate acquisition unit 243, and controls the robot 10 by position / orientation control based on the target coordinates indicated by the acquired information and the current coordinates of the end points of the tool. A control signal for controlling is generated. The position / orientation control unit 246 transmits the generated control signal to the robot 10.

The impedance control unit 247 acquires haptic information from the sensor output acquisition unit 244, and generates a control signal for controlling the robot 10 by impedance control based on the acquired haptic information. The impedance control unit 247 transmits the generated control signal to the robot 10. In the present embodiment, for example, the impedance control unit 247 has a large target value for gripping the tool with a strong force with respect to the reaction force received from the tool gripped by the hand 12;
A control signal is generated based on one of two target values, a small target value for gripping the tool with a weak force.

The control switching unit 248 switches between a control method to be applied and its target value among visual servo, position and orientation control, and impedance control. For example, the control switching unit 248 switches the control method and the target value based on the control switching condition and the control procedure stored in the storage unit 21, and the visual servo unit 245, the position / orientation control unit 246, and the impedance control The control signal generated by the unit 247 is adjusted. For example, the control switching unit 248 performs determination per degree described later, and switches the target value of the position / orientation control unit 246.

[Overview of robot system operation]
FIG. 3 is a diagram for explaining a first example of work by the robot system 1.
The X axis, the Y axis, and the Z axis exemplified in FIG. 3 and FIGS. 5, 6, and 8 to be described later indicate respective axes of the three-dimensional orthogonal coordinate system of the world coordinate system. In the first example of work,
The robot 10 performs an operation of fitting the E ring 51 to the shaft portion 62 of the work object 60 using the E ring setter 52 including the blade portion 53 and the handle portion 54. As illustrated in this figure, the hand 12 of the robot 10 holds an E-ring setter 52 that holds an E-ring 51 on a blade portion 53.

The work object 60 includes a fixed base 61, a shaft part 62, and a gear part 63. Fixed base 61
Are fixed to the work table in an arrangement that does not interfere with the operation of the robot 10, for example. The fixing base 61 fixes the shaft portion 62 so that the major axis direction of the shaft portion 62 is perpendicular to the horizontal plane.
The gear part 63 has a shape in which two large and small disks are stacked, and a hole perpendicular to the disk surface is formed at the center of the disk surface. The shaft portion 62 is passed through this hole without any gaps, and the gear portion 63.
The disk surface is kept parallel to the horizontal plane. Further, a fixing member is present below the gear portion 63, and this fixing member fixes the gear portion 63 so that the gear portion 63 does not move in the direction of gravity.

In the first example of the work, the robot system 1 performs the work of fitting the E ring 51 to the shaft part 62 on the upper part of the gear part 63 using the E ring setter 52 from the state shown in FIG.
The position where the E-ring 51 is fitted is, for example, 8.0 [mm] from the upper surface of the gear part 63 large disk.
Above. In this operation, the robot system 1 has, for example, an error of 0.
It is assumed that work accuracy of 5 [mm] or less is required.

FIG. 4 is a flowchart illustrating an example of a flow of processing executed by the control device 20 in the first example of work.
This figure shows an example of processing when the first example of the work described with reference to FIG. 3 is executed. First, the control device 20 controls the robot 10 to grip the tool with a weak force (step S).
101). Here, the weak force is such a strength that the tool does not fall or the relative posture of the tool with respect to the hand 12 does not change even when the tool is tilted. The strength of the tool is such that the relative posture of the tool with respect to the robot 10 is flexibly changed by the external force. Next, the control device 20 performs visual servo, for example, and controls the robot 10 so that the tool is in a predetermined position and posture (step S102).

Next, for example, the control device 20 performs position and orientation control, and moves the robot 10 from a predetermined position toward the reference position of the work object (step S103). The purpose of this process is to bring the end point of the tool into contact with the reference position of the work object. However, there is an error in the recognition of the end point of the tool by the robot system 1, and the tool is still in the reference position even if the reference position is the target. There is also a possibility that it does not touch the surface. Therefore, the control device 20 may move the robot 10 in the same direction until it detects contact between the tool and the reference position. Thereby, a tool can be made to contact a reference position of a work subject more certainly.

Next, the control device 20 determines whether or not the tool has contacted the reference position (step S10).
4). For example, the control device 20 determines whether or not the amount of change per unit time of the force or moment indicated by the force information acquired from the force sensor 13 is greater than a predetermined value.
It is determined whether or not the tool touches the reference position. When the tool is not in contact with the reference position (step S104; NO), the control device 20 returns the process to step S103. When the tool comes into contact with the reference position (step S104; YES), the control device 20 increases the force with which the robot 10 grips the tool by impedance control (step S105). Here, the strong force is a strength that does not change to the extent that the relative posture of the tool with respect to the hand 12 affects the work accuracy even when the tool contacts the object. Next, the control device 20
Position / orientation control based on the positional relationship between the predetermined reference position and the work position is performed, and the robot 10 is moved to the work position (step S106). Then, the control device 20 controls the robot 10 to perform the work. This is executed (step S107).

FIG. 5 is a diagram for explaining an example of the operation of the robot system 1 in the first example of work.
This figure shows an example of the operation when the first example of the work described with reference to FIG. 3 is executed.
Fig.5 (a) shows the 1st example of the positional relationship of the tool in the 1st example of work, and the work target object 60, and shows the state before the start of work.
As illustrated in this figure, the E gripped by the robot 10 before the work is started.
The ring setter 52 holds the E ring 51. A point P52 indicates an end point of the E-ring setter 52 on the blade portion 53 side. Points P11, P12, P13, and P14 each indicate a point serving as a reference for control. Points P11, P12, and P13 are on the same straight line parallel to the Z axis. The points P13 and P14 are on the same straight line parallel to the X axis. Point P
Reference numeral 12 denotes a reference position per degree. A point P14 indicates a work position. A member such as the gear part 63 is usually molded with high accuracy with an error of ± 0.05 [mm] or less, for example. In this example, the reference position is a specific position on the surface of the gear part 63, and the work position is a position 8.0 [mm] above the upper surface of the gear part 63 large disk. That is, in this example,
The relative positional relationship between the reference position and the work position is accurately determined. From this state, the robot system 1 executes, for example, the process shown in step S102 of FIG.

FIG. 5B shows a second example of the positional relationship between the tool and the work object 60 in the first example of work.
From the state illustrated in FIG. 5A, the robot system 1 performs step S10 in FIG.
When the process shown in FIG. 2 is executed, the end point P52 overlaps the point P11 indicating a predetermined position. In this example, the predetermined position is set vertically above the reference position per degree. From this state, for example, the robot system 1 executes the process shown in step S103 of FIG. 4 to move the E-ring setter 52 downward in the vertical direction, which is the direction of the reference position, as indicated by an arrow A11.

FIG. 5C shows a third example of the positional relationship between the tool and the work object 60 in the first example of work.
From the state illustrated in FIG. 5B, the robot system 1 performs step S10 in FIG.
When the process shown in FIG. 3 is executed, the E-ring setter 52 comes into contact with the reference position point P12. When the robot system 1 detects the contact between the E-ring setter 52 and the gear unit 63, the robot system 1 executes the process shown in step S105 of FIG.
Increase the gripping force of 2. From this state, the robot system 1 executes the process shown in step S106 of FIG. 4 and moves the E-ring setter 52 upward in the vertical direction as indicated by an arrow A12. At this time, the control device 20 does not set the point P13 as the target coordinate, but controls the robot 10 based on the relative position of the point P13 with respect to the point P12, for example. Specifically, in this example, since the point P12 and the point P13 exist on the same straight line parallel to the Z axis, the control device 20 controls the robot 10 so as to obtain the distance between the point P12 and the point P13. The E-ring setter 52 is moved in the Z-axis direction. That is, the control device 20 controls the robot 10 based on the change amount of the predetermined distance. Hereinafter, such position and orientation control based on the amount of change such as movement and angle is referred to as relative control.

FIG. 5D shows a fourth example of the positional relationship between the tool and the work object 60 in the first example of work.
When the robot system 1 executes the processing described with reference to FIG. 5C, the E-ring setter 52 moves to the height of the work position. In this example, the reference position point P12 and the work position point P14 are only 8 [mm] apart from each other in the height direction.
There is almost no error due to zero operation. In this example, the robot system 1
The E-ring setter 52 is moved 8 mm from the upper surface of the large disk of the gear part 63 by relative control.
Even if there is an error in the Z-axis coordinate system recognized by the robot system 1 for movement, there is almost no error in the position in the height direction in the vicinity of the reference position in the real space.
Therefore, the robot system 1 can achieve high accuracy in the height direction where high accuracy is required in the first example of work. From this state, the control device 20 performs relative control based on the relative position of the point P14 with respect to the point P13, and moves the E-ring setter 52 in the horizontal direction as indicated by an arrow A13.

FIG. 5E shows a fifth example of the positional relationship between the tool and the work object 60 in the first example of work.
When the robot system 1 executes the processing described with reference to FIG. 5D, the tool end point P5
2 moves to the working position, and the E-ring 51 is fitted to the shaft portion 62. From this state, for example, as shown by an arrow A14, the control device 20 moves the E-ring setter 5 in the direction opposite to that during fitting.
Move 2.
FIG. 5F shows a sixth example of the positional relationship between the tool and the work object 60 in the first example of work, and shows a state when the work is completed.
When the robot system 1 executes the process described with reference to FIG. 5E, the robot system 1 removes the E-ring 51 from the E-ring setter 52 and completes the operation.

For example, when the position of the tip of the hand 12 is designated in the world coordinate system based on an image captured by the imaging unit 30, an error of about 1 [mm] due to the image resolution and a calibration error 1 An error of [mm] can occur. In addition, errors in the resolution, installation position, direction, and imaging interval of the imaging unit 30 may also be errors in the position of the tip of the hand 12. Further, if an error due to the gripping position or gripping posture when the hand 12 grips the tool is included, an error of several [mm] or more may occur at the tip of the hand 12. Therefore, when the robot 10 is controlled by directly specifying the work position, there is a possibility that the work requiring high accuracy as in the first example of work may fail.

On the other hand, the control device 20 according to the present embodiment relatively controls the robot 10 after determining the position or posture of the tool according to the degree. Thereby, as an example, when the movement by relative control is about several [mm] to several [cm], or the change in angle is about several [degree], the robot 10 has an error of 0. Number [mm] or 0. Positioning with high accuracy of several degrees or less is possible. Further, according to the robot system 1, since the error is suppressed depending on the frequency of each work, the above-described image resolution, calibration error, error due to tool gripping, and the like do not accumulate.

FIG. 6 is a diagram for explaining a second example of work by the robot system 1.
In the second example of the work, the robot 10 uses the E ring setter to take out the E ring from the E ring stand and hold it. As illustrated in this figure, the work object 70 includes an E-ring stand 71 and an inclined table 74. The E-ring stand 71 includes a pedestal part 72 and a storage part 73. The lower part of the pedestal part 72 is fixed to the inclined pedestal 74 and the pedestal part 7
The upper part of 2 fixes the accommodating part 73. The upper surface of the pedestal 72 is a flat surface. The accommodating portion 73 accommodates the E-ring 51 having a flat plate shape by stacking it so that it can be taken out. In addition, the accommodating portion 73 is
The E-ring 51 is accommodated so that the plate surface of the E-ring 51 is kept parallel to the upper surface of the pedestal 72. The tilting table 74 is fixed to the work table in an arrangement that does not interfere with the operation of the robot 10, for example. Further, the tilt base 74 is fixed by tilting the E-ring stand 71 at a predetermined angle. In this example, the tilting table 74 fixes the E-ring stand 71 by tilting around the Y axis by 30 degrees with respect to the horizontal. As a result, the upper surface of the pedestal 72 and the upper surface of the E-ring 51 are inclined about the Y axis by 30 degrees with respect to the horizontal.

In the second example of the work, the robot system 1 performs the work of taking out the E-ring 51 housed in the housing portion 73 of the E-ring stand 71 using the E-ring setter 52 from the state shown in FIG. In this operation, the robot system 1 presses the blade portion 53 of the E ring setter 52 against the E ring 51 arranged in the lowermost layer among the E rings 51 arranged in a stack in the accommodating portion 73, thereby Take out the ring 51. Also, in this work, the success rate of the work is achieved by inclining the plate surface of the blade portion 53 of the E ring setter 52 downward by about 1 [degree] with respect to the plate surface of the E ring 51 and then pressing the E ring 51 against the plate surface. It is empirically known that increases.

FIG. 7 is a flowchart illustrating an example of a flow of processing executed by the control device 20 in the second example of work.
This figure shows an example of processing when the second example of the work described with reference to FIG. 6 is executed. Note that the processes shown in steps S201 to S204, S209, and S210 in FIG. 7 are the same as the processes shown in steps S101 to S104, S106, and S107 in FIG.

In step S204, when the tool touches the reference position (step S204; YE
S), the control device 20 performs impedance control, and causes the robot 10 to adjust the posture of the tool (step S205). Specifically, the adjustment of the posture of the tool is to adjust the posture of the tool based on the inclination of the plane on which the reference position exists, by causing the tool to hit the reference position. Hereinafter, the plane on which the reference position exists is referred to as a reference plane. In the present embodiment, the control device 20 adjusts the posture of the E ring setter 52 by causing the reference surface and the plate surface of the blade portion 53 of the E ring setter 52 to run in parallel. In this posture adjustment, the control device 2
0 performs impedance control based on, for example, a torsional moment detected by the force sensor 13.

Next, the control device 20 determines whether or not the impedance control has converged and the posture adjustment based on the degree has been performed (step S206). When the impedance control has not converged (step S206; NO), the control device 20 returns the process to step S205. When the impedance control has converged (step S206; YES), the control device 20 increases the force with which the robot 10 grips the tool by the impedance control (step S207).
Next, the control device 20 controls the robot 10 to tilt the posture of the tool by a predetermined angle (step S208). Next, the control device 20 performs a process similar to the process described in steps S106 and S107 in FIG. 4 and ends the process.

FIG. 8 is a diagram for explaining an example of the operation of the robot system 1 in the second example of work.
This figure shows an example of an operation when the second example of the work described with reference to FIG. 6 is executed.
Fig.8 (a) shows the 1st example of the positional relationship of the tool and work target object 70 in the 2nd example of work, and shows the state before the start of work.
As described with reference to FIG. 6, the E-ring stand 71 illustrated in this figure is inclined around the Y axis by 30 degrees with respect to the horizontal. That is, on the XZ plane, the intersection angle between the line L1 parallel to the X axis and the line L2 parallel to the upper surface of the pedestal 72 is 30 [degrees]. Housing part 73
Accommodates ten E-rings 51. A point P52 indicates an end point of the E-ring setter 52 on the blade portion 53 side. Points P21, P22, P23, and P24 are respectively
Points that serve as the basis for control. Points P21, P22, and P23 are on the same straight line.
The points P23 and P24 are on the same straight line parallel to the upper surface of the pedestal 72. Point P22 is
Indicates the reference position per degree. A point P24 indicates a work position. In this example, the reference position is a specific position on the upper surface of the pedestal portion 72, and the work position is that of the lowermost E ring 51 accommodated so that the plate surface thereof is parallel to the upper surface of the pedestal portion 72. The center. In this example, the members of the E-ring stand 71 are molded and combined with high accuracy, and the distance and posture between the upper surface of the pedestal 72 and the plate surface of the E-ring 51 may hinder the work accuracy. There is no error to come out. Therefore, the relative positional relationship between the reference position and the work position is accurately determined. From this state, the robot system 1 executes, for example, the process shown in step S202 of FIG.

FIG. 8B shows a second example of the positional relationship between the tool and the work object 70 in the second example of work.
From the state illustrated in FIG. 8A, the robot system 1 performs step S20 in FIG.
When the process shown in FIG. 2 is executed, the end point P52 overlaps the point P21 indicating a predetermined position. In this example, the predetermined position is a normal line with respect to the upper surface of the pedestal portion 72 and is set on a normal line passing through the reference position per degree. In this example, the predetermined posture may be a posture in which the E-ring setter 52 is rotated about the end point P52 in the ZA direction by several degrees around the Y axis. As a result, the robot system 1 ensures that the tool end point P52 is brought into contact with the reference position of the work object more reliably even when there is an error in the recognition of the tool posture by the robot system 1. You can adjust the posture of the tool. From this state, the robot system 1 executes, for example, the process shown in step S203 of FIG.
As shown by arrow A21, the E-ring setter 52 is moved in the direction of the reference position.

FIG. 8C shows a third example of the positional relationship between the tool and the work object 70 in the second example of work.
From the state illustrated in FIG. 8B, the robot system 1 performs step S20 in FIG.
When the process shown in FIG. 3 is executed, the E-ring setter 52 contacts the point P22 of the reference position. When the robot system 1 detects contact between the E-ring setter 52 and the pedestal portion 72, the robot system 1 executes the process shown in step S205 of FIG. 7, and changes the posture of the E-ring setter 52 as indicated by an arrow A22, for example. The upper surface of the pedestal 72, which is the reference surface, and the E-ring setter 52
The posture of the E-ring setter 52 is adjusted so that the plate surface of the blade portion 53 is parallel. At this time, the robot system 1 may adjust the posture of the E-ring setter 52 by bringing the reference surface and the plate surface of the blade portion 53 of the E-ring setter 52 into contact with each other by, for example, about several [mm ² ].

FIG. 8D shows a fourth example of the positional relationship between the tool and the work object 70 in the second example of work.
When the robot system 1 executes the process shown in step S205 of FIG. 7, the upper surface of the pedestal portion 72 and the plate surface of the blade portion 53 of the E-ring setter 52 become parallel. From this state, the robot system 1 executes the process shown in step S207 of FIG.
The gripping force of the E-ring setter 52 by 0 is increased, and the E-ring setter 52 is moved upward in the normal direction on the upper surface of the pedestal portion 72 as indicated by an arrow A23, for example. At this time, the control device 2
0 does not set the point P23 as a target coordinate, but controls the robot 10 based on the relative position of the point P23 with respect to the point P22, for example. Specifically, in this example, since the point P22 and the point P23 exist on the same straight line parallel to the normal line on the upper surface of the pedestal portion 72, the control device 20 controls the robot 10 to control the point P22 and the point P23. The E-ring setter 52 is moved upward in the normal direction on the upper surface of the pedestal 72 by the distance from P23.

FIG. 8E shows a fifth example of the positional relationship between the tool and the work object 70 in the second example of work.
When the robot system 1 executes the process described with reference to FIG. 8D, the height of the end point P52 with respect to the upper surface of the pedestal portion 72 becomes the height of the work position with respect to the upper surface of the pedestal portion 72. From this state, the robot system 1 rotates the E-ring setter 52 in the ZX direction by 1 [degree] around the Y axis around the end point P52, as indicated by an arrow A24. At this time, the control device 20 does not set the rotated posture at the point P23 as the target posture, for example,
Relative control is performed on the robot 10 based on the amount of change in the angle of rotation from the posture adjusted by the reference plane.

FIG. 8F shows a sixth example of the positional relationship between the tool and the work object 70 in the second example of work.
When the robot system 1 executes the process described with reference to FIG. 8E, the E ring setter 52 is 1 [on the plate surface of the E ring 51 housed in the housing portion 73 of the E ring stand 71. Degrees] inclines in the ZX direction. That is, on the XZ plane, the crossing angle between the line L5 parallel to the plate surface of the E ring 51 and the line L6 parallel to the major axis of the E ring setter 52 is 1 [degree]. From this state, the control device 20 performs relative control with respect to the robot 10 based on the relative position of the point P24 with respect to the point P23, and moves the E-ring setter 52 in the horizontal direction as indicated by an arrow A25. As a result, the robot system 1 can cause the E ring setter 52 to hold the E ring 51. In this example, the reference position point P2
Reference numeral 2 denotes the vicinity of the work position point P24, and in the movement from the reference position to the work position, an error in posture due to the operation of the robot 10 hardly occurs. In this example, since the robot system 1 tilts the E-ring setter 52 by relative control, even if there is an error in the XYZ coordinate system recognized by the robot system 1, the vicinity of the reference plane in the real space However, there is almost no posture error. Therefore, in the second example of work, the robot system 1 can realize high accuracy with respect to the posture of the tool for increasing the success rate of the work.

[Other configuration examples of the robot system]
In the present embodiment, the robot system 1 including the single-arm robot 10 as illustrated in FIG. 1 has been described. However, a configuration similar to that of the present embodiment is applied to a robot system including a robot different from the robot 10. Is possible.
FIG. 9 is a diagram illustrating a first example of a schematic configuration of a robot system 1a according to another configuration example.
The robot system 1a includes a robot 10a, a control device 20a, and an imaging unit 30a. The robot 10a and the control device 20a are communicably connected via a line 41. The control device 20a and the imaging unit 30a are connected via a line 42 so that they can communicate with each other. In the present embodiment, the line 41 and the line 42 are wired, for example, but may be wireless.

The robot 10a is a single arm robot including one manipulator 11a. The manipulator 11a has the same configuration as the manipulator 11 of the robot 10 described above.
The control device 20a has the same configuration as the control device 20 of the robot 10 described above. The control device 20a is an external device of the robot 10a. Thus, the robot 10a and the control device 20a may be different devices.

[Summary of the above embodiments]
As an example of the configuration, the robot 10 includes a force sensor 13, a hand 12 that holds a tool used for work, and a control unit 24 that operates the hand 12. The control unit 24 includes:
It is a robot that causes the hand 12 to perform the work after determining the position or posture of the hand 12 by bringing the tool gripped by the hand 12 into contact with the work objects 60 and 70.

As one configuration example, the control unit 24 determines the position or posture of the hand 12, changes the position or posture of the hand 12 based on a predetermined change amount, and performs the work on the hand 12. Let it be done.
Further, as one configuration example, the control unit 24 causes the hand 12 to grip the tool with a weak force before the contact, and the force that the hand 12 grips when the position or posture of the hand 12 is determined. Strengthen the hand 12 to cause the hand 12 to perform the operation.
As one configuration example, the control unit 24 brings a predetermined part of the tool held by the hand 12 into contact with the work objects 60 and 70.

As one configuration example, the robot system 1 includes a robot 10 including a force sensor 13 and a hand 12 that holds a tool used for work, and a control unit 24 that operates the robot 10, and the control The unit 24 is a robot system that causes the robot 10 to perform the work after determining the position or posture of the hand 12 by bringing the tool gripped by the hand 12 into contact with the work objects 60 and 70. .

Further, as one configuration example, the control device 20 is a control device that operates the robot 10 including the force sensor 13 and the hand 12 that holds a tool used for work, and the work target 6
The hand 12 is brought into contact with 0 and 70 by the tool held by the hand 12.
After the position or posture is determined, the control device causes the robot 10 to perform the operation.

Further, as one configuration example, the control method is a control method for operating the robot 10 including the force sensor 13 and the hand 12 that holds a tool used for work, the work target 60,
70 is a control method including bringing the tool held by the hand 12 into contact with 70, determining the position or posture of the hand 12, and causing the robot 10 to perform the operation.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

In each example described above, the manipulator may have an arbitrary degree of freedom. The manipulator has, for example, a degree of freedom of 6 axes or 7 axes or more. In addition, the manipulator may have a degree of freedom of 5 axes or less, and may have an arbitrary degree of freedom.
In each example described above, the imaging unit may be provided fixed to, for example, an upper surface, a floor surface, a ceiling, or a wall surface of a table on which the robot is installed. In addition, the imaging unit may be configured to be able to change the imaging direction, the imaging angle, and the like manually. The imaging unit may be configured to automatically change the imaging direction, the imaging angle, and the like. Further, the imaging unit may be integrated with the robot or may not be integrated.

Note that the robot system 1 may use a line as well as a point or a surface on the work object in determining the position or orientation based on the degree. The robot system 1 may determine the position or posture of the tool by bringing the tool into contact with the ridgeline of the work target.

The devices described above (for example, robots 10, 10a and control devices 20, 20a)
It is also possible to record a program for realizing the function of any of the components in a computer-readable recording medium, and read the program into a computer system for execution. The “computer system” here refers to OS (Ope
(Rating System) and hardware such as peripheral devices. Also,"
“Computer-readable recording medium” refers to a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD (Compact Disk)-
This refers to a portable medium such as a ROM or a storage device such as a hard disk built in a computer system. Further, the “computer-readable recording medium” means a volatile memory (RAM: Ran) inside a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line.
It also includes those that hold a program for a certain period of time, such as (dom Access Memory).

In addition, the above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting a program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line.
Further, the above program may be for realizing a part of the functions described above. Further, the program may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

DESCRIPTION OF SYMBOLS 1, 1a ... Robot system 11, 11a ... Manipulator, 12 ... Hand, 13 ...
Force sensor 20, 20a ... control device, 21 ... storage unit, 22 ... input unit, 23 ... output unit, 2
DESCRIPTION OF SYMBOLS 4 ... Control part, 241 ... Target image information acquisition part, 242 ... Object image information acquisition part, 243 ... Target coordinate acquisition part, 244 ... Sensor output acquisition part, 245 ... Visual servo part, 246 ... Position and orientation control part, 247 ... impedance control unit, 248 ... control switching unit, 30, 30a ... imaging unit, 40, 41, 42 ... line, 51 ... E ring, 52 ... E ring setter, 53 ... blade unit, 54 ... hand portion, 60 ... Work object, 61 ... fixed base, 62 ... shaft part, 63 ... gear part, 70 ... work object, 71 ... E-ring stand, 72 ... pedestal part, 73 ... accommodation part, 74 ... tilting table

Claims (7)

A force sensor;
A hand holding a tool used for work;
A control unit for operating the hand,
The operation is an operation of attaching an E-ring to the shaft portion of the work object,
The tool is an E-ring setter;
The controller is
After determining the position or orientation of the hand by contacting the tool the hand grips on the work object, to perform the work hand,
robot. The control unit, after determining the position or orientation of the hand, changes the position or orientation of the hand based on a predetermined change amount, and causes the hand to perform the operation.
The robot according to claim 1. Wherein, prior to said contacting, in the hand, be inclined to the tool, or tool is dropped, relative posture of a tool with respect to the hand is not or changed, the tool is brought into contact with the object when you are relative strengths posture change of tool for the robot by the contact, by gripping the tool with a first force, when the decided position or orientation of the hand, the hand is Even when the tool is in contact with an object, the gripping force is changed to a second force having a strength that does not affect the work accuracy of the relative posture of the tool with respect to the hand. To do,
The robot according to claim 1 or 2. The controller is configured to bring a predetermined part of the tool held by the hand into contact with the work object;
The robot according to any one of claims 1 to 3. A robot having a force sensor and a hand for holding a tool used for work;
A control unit for operating the robot,
The operation is an operation of attaching an E-ring to the shaft portion of the work object,
The tool is an E-ring setter;
The controller is
After determining the position or orientation of the hand by contacting the tool the hand grips on the work object, to perform the work on the robot,
Robot system. A control device for operating a robot having a force sensor and a hand for holding a tool used for work,
The operation is an operation of attaching an E-ring to the shaft portion of the work object,
The tool is an E-ring setter;
After determining the position or orientation of the hand by contacting the tool the hand grips on the work object, to perform the work on the robot,
Control device. A control method for operating a robot including a force sensor and a hand that holds a tool used for work,
The operation is an operation of attaching an E-ring to the shaft portion of the work object,
The tool is an E-ring setter;
And contacting said tool said hand grips to the work object,
Determining the position or posture of the hand;
Causing the robot to perform the work;
Control method.

Images