JPH02190285A - Hand for robot - Google Patents

Abstract

PURPOSE:To reliably prevent the generation of an abnormal reaction force in a given range by a method wherein a work grasping part is coupled to a hand body through a floating mechanism. CONSTITUTION:A work grasping part 2 is coupled to a handle body 1 through a floating mechanism 3. Even when the work grasping part 2 is pressed against a work and a tool and the like, no abnormal reaction force is generated in a given range. A press motion is continued, the work grasping part 2 is caused to approach the hand body 1 and finally an abnormal force is generated, but a relative position between the hand body 1 and the work grasping part 2 is detected by means of a state detecting means 4. As noted above, by detection of a state prevailing before an abnormal force is generated by means of the detecting means 4, the motion of a robot can be controlled so that the work grasping part 2 or a work and a tool are prevented from damage.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a robot hand, and more specifically, to a novel hand that detects the occurrence of abnormal reaction force regardless of the state of the workpiece. Regarding robot hands.

<Prior art and problems to be solved by the invention> Traditionally, industrial robots have been equipped with a hand for gripping workpieces, tools, etc., and the desired hand can be moved by operating the robot arm. The robot grasps the workpiece, tool, etc. while moving it to the desired location, and performs the necessary work.

However, the hand is generally only equipped with a tube that can be opened and closed at the tip of the robot arm, and the hand opens and closes when the robot arm moves to a predetermined position taught in advance. If a mistake occurs,
If the workpiece, tools, etc. are different from the expected ones, the workpiece,
When the conditions of the tools, etc. are different, the hand is strongly pressed against the workpiece, tool, etc., and in the worst case, there is a problem that the hand, workpiece, tool, etc. is damaged due to abnormal reaction force.

In addition, in order to solve this problem, it is possible to support the hand floating on the tip of the robot arm, but this can only deal with errors within the floating range, and the error may be significant. If the force is large, an abnormal reaction force will occur in the same manner as above, and there will be a problem that the hand, workpiece, tool, etc. will be damaged.

<Object of the invention> This invention was made in view of the above problems,
A robot hand that can detect abnormal reaction forces in advance, such as when a teaching error occurs, when the workpiece, tool, etc. is different from the expected one, or when the state of the workpiece, tool, etc. is different. is intended to provide.

Means for Solving the Problems> To achieve the above object, the robot hand of the present invention has a workpiece gripping part connected to the hand body via a floating mechanism, and a workpiece gripping part connected to the hand body. A state detection means is provided for detecting the relative position of.

However, the state detection means may be a plurality of sensors that detect a plurality of preset relative positions.
Alternatively, it may be a potentiometer that detects a plurality of preset relative positions.

If the robot hand has a structure with more than one action, the workpiece gripping part is connected to the hand body via a floating mechanism, so even if the workpiece gripping part is pressed against a workpiece, tool, etc., it will remain within a predetermined range. can reliably prevent abnormal reaction forces from occurring. If the pressing operation continues, the work gripping part approaches the hand body,
Eventually, an abnormal reaction force will occur, but since the relative position of the work gripping part to the hand body can be detected by the state detection means, the state before the abnormal reaction force is generated can be detected. By detecting this, the robot operation can be controlled so that the workpiece gripping section, workpiece, tool, etc. are not damaged.

When the state detection means is a plurality of sensors that detect a plurality of preset relative positions, the relative position between the work gripping part and the hand body can be detected in stages, and the abnormal reaction can be detected in stages. It is possible to detect not only the state immediately before a force is generated, but also the state in which a workpiece, tool, etc. can be gripped normally.

Furthermore, if the state detection means is a potentiometer that detects a plurality of preset relative positions, the relative positions to be detected can be easily changed, and the number of relative positions to be detected can also be easily changed. can be increased or decreased.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 5 is a schematic diagram showing an example of an industrial robot equipped with the robot hand of the present invention, in which a robot hand (7) is attached to the arm end of an assembly SCARA type robot (6).
is equipped with a switching valve (8) for supplying pressure fluid for opening and closing operations to the robot hand.
) is provided. A robot controller (9) is provided which receives signals indicating the robot hand (force pressing state, open/close state) and supplies necessary control signals to the switching valve (8). Of course, a control signal for operating the robot arm is output from (9). Note that (91) is an A/D converter.

Therefore, by operating the robot arm until the robot hand (7) reaches a predetermined pressing state against the workpiece, tool, etc., and opening and closing the robot hand (7) until the robot hand (7) reaches a predetermined opening/closing state, the workpiece, tool, etc. Capable of gripping and releasing tools, etc.

FIG. 4 is a schematic front view showing one embodiment of the robot hand of the present invention, in which the hand main body (1) is attached to a robot arm (not shown), and the work gripping part (2) that grips a work, a tool, etc. ), the work gripping part (2) is connected to the hand body (1) so as to be removable, and the hand body (
1), a state detection section (4) integrally attached to the workpiece gripping section (2), and a grasping position detection section (4) attached to the workpiece gripping section (2). 5).

FIG. 1A is a front view showing the floating mechanism and the state detection section in detail, and FIG. 1B is a side view, showing the hand body (
1) and the work gripping part (2) are connected to each other so as to be able to come into contact with each other through a guide shaft (31), and a coil spring (32)
) is biased to slide the two apart. Then, move the hand body (
At a predetermined position of the mounting plate (41) protruding toward 1),
Two proximity switches (4
2) (43) is installed.

Furthermore, a protrusion plate (44) for driving the proximity switch is attached so as to protrude from a predetermined position of the hand body (1) toward the work gripping part (2).

Therefore, when no external force is acting on the work gripping part (2), neither of the proximity switches (42) (43) directly faces the protruding plate (44), as shown in FIG. 2A. ,
When an external force acts on the work gripping portion (2) and the hand body (1) approaches the predetermined position, only one of the proximity switches (42) moves toward the protruding plate (44) as shown in FIG. 2B.
The workpiece gripping section (2) further faces the hand body (1).
), both the proximity switches (42) (43) directly face the protruding plate (44), as shown in FIG. 2C.

FIG. 3A is a front view showing the gripping position detection section, and FIG. 3B is a side view, in which a potentiometer (5
1) is attached, and a movable part (52) of a potentiometer (51) is connected to one of a pair of gripping claws (21) and (22) that can be moved into and out of contact with each other.

The operation of the industrial robot having the above configuration is as follows.

First, the robot arm movement necessary to grip the workpiece, tool, etc., the pressing state of the workpiece gripping part (2), the position of the gripping claws (21) (22) necessary for gripping, etc. are explained using the teaching pendant. etc., to teach in advance.

Thereafter, by causing the robot to perform operations based on the teaching data, it is possible to grasp a workpiece, tool, etc. placed at a predetermined position. After performing necessary processing based on the gripped work/tool, etc., the gripping state is released and the tool moves to the standby position to prepare for the next series of operations.

The above explanation is for the operation when the desired workpiece, tool, etc. is set accurately in the predetermined position, and when there is no workpiece, tool, etc., or when a different type of workpiece, tool, etc. is set, etc. can detect an abnormal state as follows. That is, if there is no workpiece, tool, etc., no external force will be applied even if the robot hand (7) is moved to a pre-taught position, so the workpiece gripping part (2) will not touch the hand body (1). remains the farthest from. Therefore, as shown in FIG. 2A, neither proximity switch (42) (43) directly faces the protrusion plate (44) and remains OFF, so that both proximity switches (42) (43) The absence of a workpiece, tool, etc. can be detected based on the output OFF signal. In addition, if a workpiece, tool, etc. that is higher than the normal height is set, the workpiece gripping part (2) will not move until the robot hand (7) is moved to the previously taught position. It comes very close to the hand body (1). Therefore, as shown in FIG. 2C, both proximity switches (42) and (43) directly face the protruding plate (44) and are turned on.
Based on the ON signal output from (43), it is possible to detect that an incorrect workpiece, tool, etc. is set. In the latter case, the robot hand (7
) can be prevented from acting on the robot hand, workpiece, tool, etc., and damage to the robot hand, workpiece, tool, etc. can be prevented. Incidentally, the situations shown in FIGS. 2A and 2C occur not only when the wrong workpiece, tool, etc. are set, but also when the robot is operated toward a different position due to a teaching error.

Although the above description is only for the case of gripping a workpiece, tool, etc., when releasing a workpiece, tool, etc., an OFF signal or an ON signal is output from both proximity switches (42) and (43). By doing so, it is possible to detect that the workpiece on the other side is not present or that there is a mounting error due to twisting or the like.

Furthermore, when a workpiece, tool, etc. of a regular height is set at a regular position, the workpiece, tool, etc. is grasped by bringing the gripping claws (21) (22) closer together. Since the signal indicating the amount of movement in (21) and (22) is output from the potentiometer (51),
The planar size of the workpiece, tool, etc. can be identified based on the output signal. Therefore, even if the workpieces, tools, etc. differ only in plane size, suitability can be determined reliably.

Furthermore, as is clear from the above explanation, the proximity switch (4
2) The same operation can be performed by attaching (43) to the hand body (1) side and attaching the protruding plate (44) to the work gripping portion (2) side.

<Embodiment 2> Fig. 6 is a front view of main parts showing another embodiment, and the difference from the embodiment of Fig. 1 is that the proximity switches (42) (43) and the protruding plate (44) are replaced Potentiometer (45)
This is the only point where . That is, the potentiometer (45
) is attached to the hand body (1), and the movable part (46) of the potentiometer (45) is connected to the work gripping part (2).

Therefore, in the case of this embodiment, the work gripping part (2
) and the hand body (1) is output from the potentiometer (45), and based on this output signal, it is possible to identify whether the above-mentioned abnormal state or normal state is present. Damage to the robot hand (7), workpiece, tool, etc. can be prevented. Furthermore, in this embodiment, a potentiometer (45
) can be installed easily by changing the detection position to 1F without changing the position.
In addition, the number of positions to be detected can be easily changed to +11-, which is suitable for assembly robots that handle multiple types of workpieces, tools, etc.

In addition, also in the embodiment in the above direction, the gripping claws (21) (2
2) Potentiometer (51) for detecting the amount of movement of
) It is possible to use a digital scale instead, and in this case, the A/D converter (91) becomes unnecessary, so the configuration can be simplified.

Further, the gripping claws (21) and (22) are preferably capable of gripping not only the outer shape but also the inner diameter, and can handle a wide range of workpieces, tools, and the like.

<Specific Example> FIG. 7 is a schematic perspective view showing a robot hand capable of gripping an electric screwdriver for screw tightening. The only difference is that gripping claws (23) and (24) exclusively for electric screwdrivers are integrally protruded from the portion.

FIG. 8 is a schematic vertical sectional view showing the configuration of the electric screwdriver (10), and FIG. 9 is a schematic perspective view showing the electric screwdriver (10) held on a stand, with a holder ( 11) is integrally provided, and
A replaceable screw tightening bit (12) is provided inside. A bolt holder (13) is provided at the tip end to accommodate the bolt supplied from the feeder (14) and to control the posture so that the bolt can be tightened. In addition, (15) is an electric screwdriver (1) when not required.
0) is a stand to hold it.

Therefore, in this specific example, after the robot moves to a predetermined position, the electric screwdriver (10) can be taken out from the stand (15) by moving the gripping claws (23) and (24) closer to each other. . Next, the robot moves the electric screwdriver (10) so as to directly face the screw tightening location, and by driving the electric screwdriver (10), the screw tightening can be performed.

If the workpiece to be screwed is not set, no external force will be applied to the workpiece gripping part (2) even if the robot hand (7) moves to the predetermined position, so the workpiece will not be tightened as in the above embodiment. It is possible to detect that it does not exist. On the other hand, if a workpiece that is taller than the regular workpiece is set, or if the workpiece is set in an inappropriate state, the workpiece gripping portion (2) may be Since the hand body (1) is very close to the hand body (1), it is possible to detect a workpiece setting error in the same way as in the above embodiment.

In addition, in this specific example, if the electric screwdriver (10) is simply used for temporary tightening, a SCARA type robot for normal assembly work can handle the task sufficiently, and compared to conventional screw tightening robots. A significantly inexpensive screw tightening robot can be provided.

Further, in this specific example, the state in which the electric screwdriver (10) is gripped and the state in which other workpieces, tools, etc. are gripped can be selected, so that versatility can be significantly improved.

It should be noted that the present invention is not limited to the above embodiments, and for example, the number of proximity switches (42) (42) may be reduced or increased.
43) may be replaced with a photoelectric switch or the like, and various other design changes may be made within the scope of the invention.

<Effects of the Invention> As described above, the first invention can reliably prevent the occurrence of abnormal reaction force within a predetermined range, and can also detect the state before abnormal reaction force occurs. As a result, it is possible to prevent damage to robot nodes, workpieces, tools, etc., which is a unique effect.

The second invention is capable of detecting the relative position of the workpiece gripping part and the hand body in stages, and detects not only the state immediately before abnormal reaction force occurs but also the state in which the workpiece, tool, etc. can be normally gripped. It has the unique effect of being able to detect even

The third invention has the unique effect that the relative positions to be detected can be easily changed, and the number of relative positions to be detected can also be easily increased or decreased.

[Brief explanation of the drawing]

Figure 1A is a front view showing the floating mechanism and the state detection section in detail, Figure B is a side view, Figure 2 is a diagram explaining the relationship between the proximity switch and the number of protrusions, and Figure 3A is the gripping position. FIG. 4 is a schematic front view showing an embodiment of the robot hand of the present invention; FIG. 5 is an industrial robot equipped with the robot hand of the present invention. FIG. 6 is a schematic view showing an example; FIG. 6 is a front view of main parts showing another embodiment; FIG. 7 is a schematic perspective view showing a robot hand capable of gripping an electric screwdriver for tightening screws; FIG. The figure is a schematic vertical sectional view showing the structure of the electric screwdriver, and FIG. 9 is a schematic perspective view showing the state held on a stand. Figure 3 Figure 4 (1)... Hand body, (2)... Work gripping part,
(3)...Floating mechanism, (4)...State detection section, (42) (43)...Proximity switch, (45
)...Potentiometer diagram diagram diagram diagram diagram

Claims (1)

[Claims] 1. The workpiece gripping part (2) is connected to the hand body (1) via the floating mechanism port, and the relative position of the workpiece gripping part (2) with respect to the hand body (1) is detected. A robot hand characterized in that it is provided with a state detection means (4) for detecting a state. 2. The robot hand according to claim 1, wherein the state detection means (4) is a plurality of sensors (42) (43) that detect a plurality of preset relative positions. 3. The robot hand according to claim 1, wherein the state detection means (4) is a potentiometer (45) that detects a plurality of preset relative positions.