JPH0798314B2 - Robot hand control method - Google Patents

Description

The present invention relates to a method for controlling a robot hand having two fingers.

[Prior Art] With the spread of industrial robots, robot hands have come to be used for various purposes. In order to surely grasp various objects, a robot hand having a function of detecting grasping of objects by a tactile sensor or the like is also used.

[Problems to be Solved by the Invention] However, since the conventional robot hand having such a grasping detection function only detects whether or not an object is grasped, for example, the grasped cross section is not a circle such as a rectangle. When grasping the target object, if the target object is placed at an angle or rotated by 90 degrees with respect to the predetermined position, it will not be possible to accurately grasp it, but also the target object will be specified. It was impossible to detect whether or not it was grasped in the state of. That is, even if the grasped state is not the predetermined state, the operation is continued, which causes a malfunction. Moreover, even if another object is mixed in the predetermined object, it cannot be recognized. Furthermore, when the knobs, push buttons, control levers, etc. on the front panel of the electronic device are operated by the operating robot hand, these grasped objects can move within a predetermined range, so the position of the object is constant. Instead, it has been extremely difficult to perform an accurate operation with a conventional robot hand. Therefore, in order to solve these problems with the conventional robot hand, it is necessary to provide a special identification sensor etc. to identify the object, detect the state of the object, and detect the grasped state, which complicates the device. And the rise in cost was unavoidable.

Therefore, an object of the present invention is to provide a robot capable of identifying an object and detecting a grasping state while having a simple configuration.
It is to provide a method of controlling the hand.

Another object of the present invention is to provide a robot hand capable of automatically performing a grasping operation again when an object having a non-circular grasping section is not grasped in a prescribed state and accurately grasping the object in a prescribed state. It is to provide a control method.

Another object of the present invention is to provide a method of controlling a robot hand capable of reliably grasping a movable object within a predetermined range and automatically performing a predetermined work.

[Means and Actions for Solving the Problem] According to the robot hand control method of the present invention, the approximate centers of the two fingers are aligned with the position of the target object so that the predetermined length is shorter than the maximum outer diameter of the target object. When the distance between the two fingers is narrowed toward the front and the object is grasped before the distance between the two fingers reaches the predetermined length, grasping of the object is detected. If the target object is not grasped even after reaching the predetermined length, it can be determined that the object is not grasped. With this, it is possible to prevent an object having an outer diameter shorter than the predetermined length from being mistakenly grasped,
The object can be identified. Further, the grasped state of the object can be detected by appropriately setting the predetermined length according to the shape of the grasped object.

The control method of the robot hand of the present invention, when the grasped cross section of the object is non-circular, rather than grasping the position of the maximum outer diameter,
It is based on the fact that it is more stable to know the position of the minimum outer diameter. That is, when the position of the outer diameter longer than the predetermined length is grasped, the operation of once opening the two fingers, rotating the fingers around the object by a predetermined angle, and grasping again is repeated. Then, when the object cannot be grasped even if the distance between the fingers is reduced to a predetermined length, it can be determined that the positions of the two fingers are aligned with the position of the minimum outer diameter of the object. Then, the object can be grasped at that position and a predetermined operation can be performed. Therefore, when the object is grasped at a position longer than the predetermined length, the grasping operation can be redone and the finger can be rotationally moved to the predetermined position to reliably grasp the object at the position of the minimum outer diameter.

[Embodiment] FIG. 2 is a schematic view of a robot hand apparatus 10 suitable for using the robot hand control method of the present invention.
The robot hand device 10 has a grasping means having two fingers 13.
12 includes a driving means 14 and a controller 16. A table 18 is placed next to the robot hand device 10, and an object 20 is placed at a predetermined position on the table 18. The driving means 14 moves the position of the grasping means 12 back and forth according to a control signal supplied from the control device 16 via the cable 15.
In addition to moving to the left and right and up and down, the opening and closing of the two fingers 13 of the grasping means 12 is also driven to enable a predetermined work such as grasping the object 20 at a predetermined position on the table 18. Also,
The grasping means 12 is rotatable about a central axis between two fingers and grasps the object 20 with a finger 13 to rotate the object 20, or a finger around the object with the finger open. Can be rotated to change the grasping positions of the two fingers with respect to the object 20. The drive mechanism in the drive means 14 may be any mechanism such as a pneumatic mechanism such as an air actuator or an electric mechanism using a DC motor, but the position of the grasping means 12 or two fingers. It is necessary to be able to control the opening and closing of the with high precision. Further, the driving means 14 also has a grasp detecting means for detecting whether or not the grasping means 12 grasps the object, but a method of directly detecting the contact pressure between the finger and the object by a contact sensor or the like, or Any method such as a method of indirectly detecting the tension generated in the driven shaft or wire may be adopted. When the grasp of the object 20 is detected, the control device
The operation of the driving means 14 is stopped by the control signal from 16.
The object 20 is gripped by the two fingers 13 with a predetermined gripping force. Further, in the robot hand device 10, the driving means 14 drives the grasping means 12 in response to a control signal from the control device 16 to adjust the distance between two fingers to a predetermined length. By using this function, it is possible to achieve new functions such as identification of a predetermined object and detection of a grasping state. This will be described later in detail.

FIG. 3 is a block diagram showing the configuration of the control device 16.
In the control device 16, a microprocessor (μP) 22,
Read-only memory (ROM) 24, random access
A memory (RAM) 26, a keyboard 28, a display device 30, an external storage device 32, and an interface circuit 34 are connected to the bus 36. Μ according to the command input from the keyboard 28
The P22 reads out the programs and data stored in the ROM 24 and the RAM 26 and executes the control of the driving means 14 connected via the interface circuit 34. If necessary,
Information in the external storage device 32 such as a floppy disk is stored in RAM2
Transferred within 6. In the external storage device 32, information such as the number of the objects 20 shown in FIG. 2, the position of each object and the size of the grasped cross section of each object, and a program for operating the objects with the robot hand 10 are shown. Is remembered. μP22 is
A control signal is sent to the driving means 14 of FIG. 2 according to a program created based on the information such as the position and outer diameter of the object 20 to control the grasping means 12. In particular, it should be noted that the distance between the two fingers 13 can be adjusted with high accuracy based on the program. Input information from the keyboard 28, control information executed by the μP 22, and the like are displayed on the display device 30.

FIG. 1A is a flow chart showing an embodiment of a method for controlling a robot hand according to the present invention. After starting at block 40, at block 42 the μP 22 sends a control signal to the drive means 14,
The two fingers 13 are opened, and the approximate centers of the fingers are aligned with the position of the object 20. Next, in the block 44, the distance between the two fingers 13 is narrowed toward a predetermined length shorter than the maximum outer diameter of the grasped cross section of the object. At the next decision block 46, it is detected whether or not the object 20 is grasped. Fourth example of grasping section of the object 20
Shown in the figure. The length indicated by a in FIG. 4 is the maximum outer diameter of the object 20. The length indicated by b is the minimum outer diameter of the grasped cross section of the object 20. When stably grasping an object having such a shape, it is desirable to grasp at the position of the minimum outer diameter b. The predetermined length in block 44 of FIG. 1A is the object
The size is set to be shorter than the maximum outer diameter a of 20 and slightly longer than the minimum outer diameter b. In decision block 46, if a grasp is detected before the finger spacing reaches a predetermined length, then two fingers are grasping the protruding portion of the object 20. If a grasp is detected, the process proceeds to block 48 where the two fingers 13 are opened and the fingers are rotated about the object by a predetermined angle. The process then returns to block 44 and the block
Blocks 44, 46, and 46 until no grasps are detected
48 steps are repeated. If no grasp is detected in block 46, this is the two outer diameters b of the object 20
It means that it exists in the position of. Therefore, the process proceeds to block 50, and the two fingers surely grasp the object 20,
According to the program, perform a predetermined work, block 52
Then, the processing of this flow chart ends. In this flow chart,
When the grasped cross section of the object is substantially circular and may be grasped at any position, the procedure of returning from the block 48 to the block 44 may be omitted. In that case, when the grasping of the target object is not detected in block 46, the predetermined target object does not exist and the flow of the outer diameter is shorter than the predetermined length, so that the target object can be used for identification. In addition, if the predetermined length is appropriately adjusted according to the shape and size of the object, the grasping state of the object is detected, for example, when grasping a rectangular object in the longitudinal direction rotated 90 degrees from the predetermined position. You can That is, in the case of a rectangular object, the predetermined length of the block 46 is set to be slightly longer than the shorter side and slightly shorter than the longer side. If the grasp is detected before the finger distance reaches the predetermined length, it means that the rectangular object is grasped in the longitudinal direction. When grasping is not detected even when the distance between the fingers reaches a predetermined length, the finger is positioned to grasp the short side of the rectangular object.
Furthermore, by adding the block 48, even if the protruding portion of an object having a non-circular grasping section is grasped, the grasping operation can be automatically redone to grasp the object at an optimum position.

FIG. 1B is a flow chart showing another embodiment of the robot hand control method of the present invention. This control method is suitable for grasping and operating a target object such as a switch, a knob, and a movable lever on the front panel of an electronic device that can be moved within a predetermined range and whose existing position is not constant. . After starting at block 60, at block 62 the two fingers 13 are opened and the center of the fingers is aligned with a predetermined position within the movable range of the object. Then, in the block 64, the distance between the two fingers 13 is narrowed toward a predetermined length shorter than the maximum outer diameter of the grasped cross section of the object 20. Thereafter, in block 66, it is detected whether or not the object 20 is grasped, and if not, the process proceeds to block 68. Now open the two fingers 13,
Move the center of the finger to another position within the range in which the object can move. The process of blocks 64, 66 and 68 is then repeated until a grasp is detected. When the grasp of the object is detected in block 66, the process proceeds to block 70, a predetermined work is performed according to the program, and the control method ends in block 72. By this method, it is possible to reliably grasp and operate an object that is movable within a predetermined range and whose position is not constant.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described herein, and it is understood by those skilled in the art that various modifications, changes and applications can be made if necessary. it is obvious. For example, in the embodiment, the predetermined length, which is a reference for narrowing the interval between the fingers, is set shorter than the maximum outer diameter of the target object, but the predetermined length is set longer than the maximum outer diameter of the target object to detect the grasp, Even when an object having an outer diameter longer than the target object is mixed, it can be identified.

[Effect of the Invention] According to the control method of the robot hand of the present invention, the distance between two fingers is controlled by using the information on the outer diameter dimension of the grasped object, and the grasp is detected in relation to the predetermined length. By doing so, it becomes possible to identify whether or not the object is a predetermined object and to detect the grasping state of the object. Further, when grasping an object having a non-circular grasping cross section, when grasping a protruding portion, the grasping operation can be automatically redone, and the portion having the minimum outer diameter can be grasped reliably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a flow chart showing one embodiment of a robot hand control method according to the present invention, FIG. 1B is a flow chart showing another embodiment of the present invention, and FIG. FIG. 3 is a schematic diagram of a robot hand device suitable for using the present invention, FIG. 3 is a block diagram showing the configuration of the control device of FIG. 2, and FIG. 4 is an example of a grasping cross section of an object. It is a figure. 10 …… Robot hand device 12 …… Gripping means 13 …… Two fingers 14 …… Driving means (grasping detection means) 16 …… Control device 20 …… Target 22 …… Microprocessor (μP)

Claims (2)

[Claims] 1. A grasping means capable of grasping an object having a known outer diameter by opening and closing the two fingers, a grasping detecting means for detecting grasping of the object, and a grasping of the two fingers. A method for controlling a robot hand, comprising: a control means for controlling a position interval; (a) aligning a substantially center between the two open fingers with a position of the object; The distance between the grasping positions of the two fingers is narrowed toward a predetermined length shorter than the maximum outer diameter of the object and longer than the minimum outer diameter, and (c) whether or not the two fingers grasp the object. (D) If the object is not grasped even if the distance between the grasping positions of the two fingers is narrowed to the prescribed length, the object is grasped by the two fingers and a predetermined operation is performed. A method for controlling a robot hand, characterized by: 2. A grasping means capable of grasping an object having a non-circular grasping cross section and a known outer diameter dimension by opening and closing movements of two fingers, grasping detecting means for detecting grasping of the object, and A control method for a robot hand, comprising: a control means for controlling a distance between grasping positions of two fingers and a rotation means capable of rotating the two fingers around a central axis of the two fingers. (A) Align the approximate center between the two open fingers with the position of the object, and (b) make the distance between the grasping positions of the two fingers shorter than the maximum outer diameter of the object and minimum. Narrowing toward a predetermined length longer than the outer diameter, (c) detecting whether or not the two fingers grasp the object, and (d) if grasping the object, the above-mentioned 2 Open two fingers and rotate the two fingers around the object by a predetermined angle, (e) the robot Steps (b) to (d) are repeated until the hand does not grasp the object, and (f) grasps the object even if the distance between the grasping positions of the two fingers is reduced to the predetermined length. If not, a method of controlling a robot hand, characterized in that the object is grasped by the two fingers and a predetermined work is executed.