JP3925020B2 - Robot control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a robot control apparatus. For example, when an articulated robot detects the position and orientation of a part randomly placed in a box with an image processing device and then performs a bin picking operation to take out the part, it automatically generates a robot motion trajectory. Applicable to robot controller capable of
[0002]
[Prior art]
FIG. 7 shows a bin picking system used for an operation (bin picking) of taking out parts randomly placed in a box by an image processing apparatus.
This system is composed of 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 an image of the camera 01, and the three-dimensional image is detected. The position and orientation are measured, and the robot arm 04 handles the object based on the measurement result sent to the robot controller 04.
[0003]
[Problems to be solved by the invention]
In the conventional bin picking system described above, there are cases where picking cannot be performed due to a recognition error or the like of the image processing apparatus.
If picking fails, the object may be recognized again by image processing and picking may be repeated.
[0004]
For example, as shown in FIG. 8, when the parts 06 are randomly placed in the box 05, the robot controller 03 automatically generates a trajectory for taking out the parts 06, as shown by arrows in FIG. Then, the robot hand 03a of the robot arm 03 is operated.
Here, if the position / posture of the target component 06 is correctly recognized, the robot hand 03a can grasp and take out the component 06, but if the image processing device 02 has an error in recognition, The component 06 cannot be gripped, and picking fails.
[0005]
Even when the picking has failed, conventionally, the picking is performed by retreating from the box 05 along the motion trajectory as shown in FIG.
At this time, since the part 06 has not been taken out, there is no change in the state of the box (part arrangement, etc.).
Therefore, since the image processing apparatus 02 performs image processing on the same camera image, it is often erroneously recognized again.
If erroneous recognition of the image processing apparatus 02 is repeated, picking cannot be performed after all.
[0006]
Thus, once erroneous recognition occurs, picking often fails many times.
In the past, when picking failed several times in succession, the inside of the box was mixed to change the state of the inside of the box, but this process takes time and increases the tact time. There was a problem.
[0007]
[Means for Solving the Problems]
Control device according to claim 1, wherein the robot of the present invention for solving the above-mentioned problems, with respect to the articulated robot to perform the picking operation by gripping the components inside the box with the robot hand, the operation is the part of the robot hand To change the state of component placement, component orientation, etc. in the box when it is determined that the gripping of the component has failed by monitoring whether the predetermined amount for gripping is exceeded. In addition, instead of immediately moving to the retreating operation, an operation trajectory is generated that draws the parts to the center of the box.
[0008]
The robot control apparatus according to claim 2 of the present invention for solving the above-described problem is that the articulated robot according to claim 1 includes a force sensor for performing force control, and a constant force is applied by the force sensor. The articulated robot is operated so as to be detected.
[0009]
The robot control apparatus according to claim 3 of the present invention for solving the above-described problems is such that the articulated robot according to claim 1 can be moved up and down by a spring mechanism, and the state of the vertical movement can be detected by a limit switch. It is characterized by that.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
In this embodiment, when the part cannot be gripped, the state of the part in the box, the state of the part, and the like are changed so that the image processing apparatus does not continuously make erroneous recognition. As shown by the arrows in FIG. 5, when the robot controller generates a motion trajectory for the robot hand 03a to draw the component 06 to the center of the box and the component 06 cannot be gripped, the robot hand 03a is moved according to the generated activation. To work.
[0011]
That is, when the gripping fails, the drawing operation by the robot hand 03a is performed from that place.
In this case, even if the robot hand 03a cannot be gripped, the robot hand 03a is operated with the expectation that the nail of the robot hand 03a is caught on the workpiece.
The drawing operation as in the present embodiment is effective when the image processing apparatus makes a mistake in the posture of the component.
In addition, even when a component other than the target component cannot be hit and gripped, the position and orientation of the disturbing component can be changed.
[0012]
Here, whether or not the gripping is successful can be known from the gripping position.
In FIG. 1, a nail is opened by inserting a nail into a hole in order to grasp the workpiece. At this time, a success or failure in grasping is detected by attaching a sensor to monitor whether or not the nail is opened more than a predetermined amount. Can be judged.
Therefore, when the gripping fails, the position and orientation of the component are changed without increasing the tact time by operating from the gripping position toward the center of the box.
[0013]
In the present embodiment, by pulling the component 06 to the center of the box 05, the state inside the box 05 can be changed, and the image processing apparatus can be prevented from repeating erroneous recognition.
In addition, since the operation is continuously performed without evacuation and then drawn, the influence on the tact time can be reduced, and the erroneous recognition of the image processing apparatus can be reduced, so that the tact time can be shortened as a whole.
[0014]
When gripping fails, when returning the robot hand to the retracted position and performing the scraping operation from the retracted position, a series of trajectories for returning to the retracted position must be calculated in advance, and the scraping operation is performed. However, in this embodiment, since a trajectory different from the extraction trajectory calculated in advance from the position where the gripping is performed is operated, such time can be saved. .
[0015]
The motion trajectory in the present embodiment is generated by, for example, a robot controller shown in FIG.
The robot controller 40 includes a work picking position calculating unit 41, a picking path calculating unit 42, a robot program analyzing unit 43, a robot operation planning unit 44, a servo calculating unit 45, a servo driver 46, a robot program 47, a parameter setting changing unit 48, A storage means 49 is provided, and the robot arm 30 is operated based on the three-dimensional position and orientation of the object obtained by the image processing apparatus 20 or the like.
[0016]
Here, as shown in FIG. 5, information such as the shape, position, and posture of the box is stored in advance in the storage unit 49 by the parameter setting changing unit 48, and the robot operation planning unit 44 sets this parameter during operation. With reference to this, an operation trajectory is automatically generated in the robot controller 40.
[0017]
[Example 2]
In the present embodiment, force control is performed so that the part can be surely drawn to the center of the box, and the part can be moved while being reliably maintained in contact with the workpiece.
When the robot hand 03a is operated according to the first embodiment described above, the component 06 is slightly shifted as shown in FIG. 2, but in some cases, the state in the box such as the arrangement of the component 06 cannot be changed at all. There is.
[0018]
Therefore, in order to enable force control to move the hand to the center of the box in a state where it is reliably in contact with the parts, force control is performed as shown in FIG. Can be changed.
The force control is performed in the direction in which the workpiece is pressed as shown in FIG. 4, and the force sensor 50 is attached between the hand 51 and the robot hand 52 as shown in FIG. Detects contact force with parts.
[0019]
As shown in FIG. 6, the contact force detected by the force sensor 50 is input to a robot motion planning unit 54 including a trajectory planning unit 54a, a trajectory combining unit 54b, and a force control unit 54c.
Based on the contact force detected by the force sensor 50, the force control unit 54c generates a force command for generating the force f in the pressing direction of the workpiece and outputs the force command to the trajectory synthesis unit 54b. A command to move to the center of the box is generated by performing position control in the direction of.
The magnitude f of the force is a parameter whose setting can be changed, and is stored in the storage unit 49 by the parameter setting changing unit 48 shown in FIG.
[0020]
Example 3
In the second embodiment described above, the force sensor 50 is required to perform force control. However, the force sensor is expensive and has low rigidity with respect to the robot arm and the hand, and thus is easily broken.
Therefore, the hand can be moved up and down by a spring mechanism, and the state of vertical movement can be detected by a limit switch.
[0021]
【The invention's effect】
As described above in detail based on the embodiments, when the robot detects that the robot has failed to grip the part, the present invention does not immediately move to the retracting operation but moves from the gripping position to the center of the box. By retreating after moving, by changing the state in the box even when the image processing device is misrecognized, the misrecognition of the image processing device is not continued. Failure is reduced.
This reduces the time required to remove all parts from the box.
In addition, since the robot controller performs these trajectory generations, teaching work is unnecessary 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 the robot hand is operated according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram showing a state when a robot hand according to Embodiment 2 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 parts 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 Unit 42 Picking Path Calculation Unit 43 Robot Program Analysis Unit 44 Robot Operation Planning Unit 45 Servo Calculation Unit 46 Servo Driver 47 Robot program 48 Parameter setting changing means 49 Storage means

Claims (3)

For an articulated robot that performs picking work by gripping a part with a robot hand in a box, monitoring whether the operation of the robot hand exceeds a predetermined amount for gripping the part When it is determined that the gripping of the part has failed, the part is brought to the center of the box instead of immediately moving to the retreating operation in order to change the state of the part placement and the part posture in the box. A control apparatus for a robot, characterized by generating such an operation trajectory.   2. The robot according to claim 1, wherein the articulated robot includes a force sensor for performing force control, and operates the articulated robot so that a constant force is detected by the force sensor. Control device.   2. The robot control apparatus according to claim 1, wherein the articulated robot can be moved up and down by a spring mechanism, and the state of the vertical movement can be detected by a limit switch.

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