JP2001179669A - Control device for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for robot capable of changing a situation inside a box even if an image processing device makes error recognition to prevent a succession of error recognition of the image processing device. SOLUTION: An articulated robot adapted to perform picking works inside the box is to make a working track so as to have the box drawn to center of the box without shifting to a withdrawal movement at once to change situation such as a layout of part and a position of part inside the box if the robot fails to pick up the part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a robot. For example, in an articulated robot, after detecting the position and orientation of a part randomly placed in a box with an image processing device, when performing bin picking work to remove this part, automatically generating the motion trajectory of the robot Applies to robot controllers that can

[0002]

2. Description of the Related Art FIG. 7 shows a bin picking system used for an operation (bin picking) for taking out parts randomly placed in a box in an image processing apparatus. This system includes a camera 01, an image processing device (vision system) 02, a robot arm 03, and a robot controller 04. The image processing device 02 detects an object based on the image of the camera 01, and detects a three-dimensional object. The position and orientation are measured, and the robot arm 04 handles an object based on the measurement result sent to the robot controller 04.

[0003]

In the above-described conventional bin picking system, picking may not be performed due to a recognition error of the image processing apparatus. If the picking fails, the object may be recognized again by image processing and picking may be repeated.

For example, as shown in FIG. 8, when a part 06 is randomly placed in a box 05,
The trajectory for taking out 6 is automatically generated by the robot controller 03, and the robot hand 03a of the robot arm 03 is operated as shown by an arrow in FIG. Here, if the position and orientation of the target component 06 are correctly recognized, the robot hand 03a can grasp and take out the component 06, but if there is an error in the recognition of the image processing device 02, Since the part 06 cannot be gripped, the picking fails.

[0005] Even when picking has failed, conventionally, it has been repeated to retreat from the box 05 with an operation trajectory as shown in Fig. 9 and to recognize the object again by the image processing device 02 and perform picking. At this time, since the part 06 has not been taken out, the state in the box (part arrangement, etc.) does not change. Therefore, since the image processing apparatus 02 performs image processing on the same camera image, the image processing apparatus 02 often ends up erroneously recognizing it. If the erroneous recognition of the image processing device 02 is repeated, picking cannot be performed after all.

[0006] As described above, once erroneous recognition occurs, picking often fails. conventionally,
When picking failed several times in succession, the process of stirring the inside of the box and changing the state of the inside of the box was performed, but this process takes a long time and increases the tact time. there were.

[0007]

According to a first aspect of the present invention, there is provided a robot control apparatus which solves the above-mentioned problems, when an articulated robot performing a picking operation in a box fails to grip a part. In order to change the state such as the arrangement of parts in the box and the posture of the parts, instead of immediately moving to the evacuation operation, an operation trajectory that draws the parts to the center of the box is generated. And

According to a second aspect of the present invention, there is provided a robot control apparatus according to the first aspect, wherein the articulated robot according to the first aspect includes a force sensor for performing force control, and the force sensor detects the force. Characterized in that the articulated robot is operated so that the force is detected.

According to a third aspect of the present invention, there is provided a robot control apparatus according to the first aspect, wherein the articulated robot can be moved up and down by a spring mechanism, and a state of the up and down movement is detected by a limit switch. It is characterized by being made possible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] In this embodiment, when a part cannot be gripped, the state of the arrangement of parts in the box and the posture of the parts are changed, and the image processing apparatus is continuously operated. In order to prevent erroneous recognition, the robot controller generates a motion trajectory for the robot hand 03a to draw the component 06 to the center of the box as shown by an arrow in FIG. Operates the robot hand 03a in accordance with the generated activation.

In other words, when the gripping has failed, the robot hand 03a performs a pulling operation from the spot. This is to operate the robot hand 03a in expectation that the claws of the robot hand 03a will be caught on the workpiece even if the robot hand 03a cannot grasp the workpiece. The drawing operation as in the present embodiment is effective when the image processing apparatus makes a mistake in the orientation of the component. Further, even in the case where it is impossible to grasp the target by colliding with a component other than the target component, the position and orientation of the obstructing component can be changed.

[0012] Here, whether or not the grip is successful can be known from the grip position. In FIG. 1, the nail is opened by inserting a nail into the hole in order to grasp the workpiece. At this time, the sensor is attached and monitored to see if the nail is opened too much. Can be determined. Therefore, when the gripping fails, the component is moved from the gripping position toward the center of the box, and the position and orientation of the component is changed without increasing the tact.

In this embodiment, the state of the inside of the box 05 can be changed by pulling the part 06 to the center of the box 05, and the image processing apparatus can be prevented from repeating erroneous recognition. In addition, since the operation is performed once without retreating and then attracted, the influence on the tact time is small, and erroneous recognition of the image processing apparatus can be reduced. As a result, the tact time can be shortened as a whole.

If the robot hand is returned to the retracted position when the grasping fails, and a scraping operation is performed from the retracted position, a series of trajectories for returning to the retracted position must be calculated in advance. Although the process for performing the operation takes time, in the present embodiment, a trajectory different from the takeout trajectory calculated in advance from the gripping position is operated, so such time is omitted. be able to.

The motion trajectory in this embodiment is generated by, for example, a robot controller shown in FIG. The robot controller 40 includes a work picking position calculation unit 41, a picking path calculation unit 42, a robot program analysis unit 43, a robot operation planning unit 44, a servo calculation unit 45, a servo driver 46, a robot program 47,
The robot arm 30 includes a parameter setting change unit 48 and a storage unit 49, and operates the robot arm 30 based on the three-dimensional position and orientation of the object obtained by the image processing apparatus 20 or the like.

Here, as shown in FIG. 5, information such as the shape, position, and posture of the box is stored in advance in the storage means 49 by the parameter setting change means 48. At the time of operation, the robot operation planning unit 44 The operation trajectory is automatically generated in the robot controller 40 with reference to this parameter.

[Embodiment 2] In this embodiment, force control is performed so that a part can be reliably drawn to the center of a box.
This is to make it possible to move while reliably maintaining the contact state with the work. When the robot hand 03a is operated according to the first embodiment described above, the part 06 is slightly shifted as shown in FIG. 2, but in some cases, the state of the inside of the box such as the arrangement of the part 06 cannot be changed at all. There is.

Therefore, in order to perform force control and to enable the hand to move to the center of the box in a state in which the hand is securely in contact with the parts, as shown in FIG. It is possible to reliably change the state. The force control is shown in FIG.
The force sensor 50 is attached between the hand 51 and the hand 52 of the robot, as shown in FIG. 4, to measure the contact force between the hand 51 and other parts. To detect.

As shown in FIG. 6, the contact force detected by the force sensor 50 is input to a robot operation planning unit 54 including a trajectory planning unit 54a, a trajectory synthesis unit 54b, and a force control unit 54c. The force control unit 54c includes the force sensor 5
Based on the contact force detected by 0, a force command for generating a force f with respect to the pressing direction of the work is generated and output to the trajectory synthesis unit 54b, and the position control is performed for other directions. By doing so, a command to move to the center of the box is generated. The magnitude f of the force is a parameter whose setting can be changed, and is stored in the storage means 49 by the parameter setting changing means 48 shown in FIG.

[Embodiment 3] In the above-described embodiment 2, the force sensor 50 is required to perform force control. However, since the force sensor is expensive and has low rigidity with respect to the robot arm and the hand, Fragile. Therefore, the hand can be moved up and down by a spring mechanism, and the state of up and down movement can be detected by a limit switch.

[0021]

As described above in detail with reference to the embodiments, when the present invention detects that the robot has failed to grip a part, the robot does not immediately move to the evacuation operation, but instead moves from the grip position. By moving to the center of the box and evacuating, changing the state inside the box even when the image processing device is erroneously recognized, so that the erroneous recognition of the image processing device does not continue, And therefore picking failures are reduced. This reduces the time required to remove all parts from the box. Further, since these trajectories are generated by the robot controller, a teaching operation is not required unlike the conventional teaching playback.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an operation trajectory of a robot hand according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state when a robot hand is operated according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a state when a robot hand according to a second embodiment of the present invention is operated.

FIG. 4 is an explanatory diagram showing force control.

FIG. 5 is a block diagram of a robot controller.

FIG. 6 is a block diagram of a robot operation planning unit.

FIG. 7 is a configuration diagram of a bin picking system.

FIG. 8 is an explanatory view showing a box in which components are randomly placed.

FIG. 9 is an explanatory diagram showing an operation trajectory of a conventional robot hand.

[Explanation of symbols]

 01 Camera 02 Image processing device 03 Robot arm 03a Robot hand 04 Robot controller 05 Box 06 Parts 40 Robot controller 41 Work picking position calculation means 42 Picking path calculation means 43 Robot program analysis unit 44 Robot operation planning unit 45 Servo calculation unit 46 Servo driver 47 robot program 48 parameter setting change means 49 storage means

Claims (3)

[Claims] 1. An articulated robot that performs a picking operation in a box and immediately retreats in order to change the state of the parts in the box and the posture of the parts when the gripping of the parts fails. A robot control device characterized by generating a motion trajectory that draws a part to the center of a box instead of moving to a center. 2. The multi-joint robot includes a force sensor for performing force control, and operates the articulated robot such that a constant force is detected by the force sensor. Item 2. A control device for a robot according to Item 1. 3. The robot controller according to claim 1, wherein the articulated robot can be moved up and down by a spring mechanism, and a state of the up and down movement can be detected by a limit switch.