JP2977626B2 - Work evaluation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work evaluation device,
In particular, the present invention relates to a work evaluation device such as a robot or an automatic machine (hereinafter, represented by a robot).

In general, robot operations are superior to manual operations in terms of repetitive stability, and are particularly useful for assembling and inspecting precision equipment (eg, electronic components) that require stable positional accuracy. . However, humans have extremely sensitive and sophisticated sensory adjustment functions, which point to the limitations of robot performance.

[0003]

2. Description of the Related Art FIG. 9 is a block diagram of a conventional robot.
Reference numeral 0 denotes an assembly, reference numeral 11 denotes a component to be attached to the assembly 10, reference numeral 12 denotes a hand for gripping the component 11, and reference numeral 13 denotes a robot main body for turning and moving the hand up and down. A force sensor 14 is attached between the robot body 13 and the hand 12, and the force sensor 14
Detecting an external force applied to and outputs into an electric signal S _1. Controller 15 converts the arithmetic unit 15a for calculating the force control quantity S ₃ is compared with the force target value S ₂ from the signals S ₁ and the computer 16, the force control quantity S ₃ to the servo signal S ₄ Servo and a control unit 15b, to drive the servo motor of the robot body 14 (not shown) by a signal S ₄ from the servo control unit 15b, controls the servo signal S ₄ by feeding back the rotation angle of the servo motor .

FIG. 10 is a view showing an example of the operation by the robot, in which a part 11 (for example, a peg) held by a hand 12 is inserted into a hole 10 a of an assembly 10.
Such work is a work form often seen in the field of assembly of electronic devices and the like.

[0005] Completion of the insertion of the component 11 is determined when the signal S ₁ from the force sensor 14 reaches a predetermined detection level. That is, when the component 11 hits the bottom of the hole 10a, a large external force (corresponding to the reaction force of the descending force of the hand 12) acts on the component 11, and the completion of the insertion of the component 11 is detected by detecting this external force level. Can be determined.

[0006]

However, such a conventional robot has only a detection level for judging the completion of insertion. For example, when the cross-sectional area of the component 11 is substantially equal to the opening area of the hole 10a. Therefore, there is a problem that the work cannot be interrupted when the component 11 is very slightly inclined, when the outer wall surface of the component 11 or the inner wall surface of the hole 10a is rough, or when the wall surface has minute projections.

FIG. 11A is a graph showing the relationship between the force signal S ₁ and the detection level in the above case.
(B) is a graph showing the force signals S ₁ and the detection level of the relationship between the above case. In these graphs, the signal S
_The point ( ₁ ) and the point (B) where the ₁ rises rapidly are the parts 11
Is the insertion completion point.

(C) is a signal S ₁ level when the component 11 is hooked on the protrusion during insertion, and corresponds to a force for stopping the lowering of the component 11. Although such a force depends on the degree of the protrusion, it is generally much smaller than the external force at the time of completion of insertion, and therefore cannot be determined at the detection level for determining completion of insertion.

[0009] (d) at the level of the signals S ₁ due to the roughness of the wall surface finish, which also is generally much smaller than the external force of the insertion completion can not be determined in the same manner. Accordingly, an object of the present invention is to provide a work evaluation device that can determine an abnormality during hand work by evaluating the magnitude of a force acting on the hand.

[0010]

According to a first aspect of the present invention, there is provided a work evaluation apparatus, comprising:
An external force detecting means for detecting an external force acting on the hand holding the component, and a signal level based on the signal representing the detected external force.
Extraction means for extracting the average of the vibration level and the impulse waveform, and the average of the signal level and the vibration of the vibration waveform.
An evaluation means for comparing and analyzing the time series change pattern and a predetermined reference value for the width and the amplitude of the impulse waveform, and judging and evaluating an abnormal hand operation and an abnormal part shape based on the analysis result; And control means for controlling the continuation and interruption of the hand work based on the result.

[0011]

When a hand inserts a part into an arbitrary hole by a hand, various pieces of progress information during the insertion are all transmitted to the hand as external force. In other words, by analyzing this external force, various abnormalities that occur during the work , such as
For example, the protrusion (described above) can be detected from the protrusion of the external force signal,
The roughness of the surface finish (described above) depends on the DC component of the external force signal.
Minute increase, and based on this detection result
The continuation and interruption of hand work can be controlled appropriately.
You.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 and 2 are views showing a first embodiment of a work evaluation device according to the present invention.

In FIG. 1, reference numeral 20 denotes a component, 21 denotes a hand, and the hand 21 is attached to a robot body 23 via a force sensor (external force detecting means) 22. The robot body 23 includes a servomotor (not shown) driven by a servo signal.
Can be moved up and down and positioned.

The evaluation device 24 receives the position data signal Sa from the robot body 23 , that is, the rotation angle signal of the servomotor, the force signal Sb from the force sensor 22, and the like, and extracts and evaluates predetermined components from these signals (described later). ) is executed, the signal Sc for determining the completion or abnormal state of the work by the hand 21, Sd, and generates a Se computer
(Control means) Output to 25.

The computer 25 computes control amounts necessary for the work, such as the target position of the hand 21 and the lifting / lowering force, and also terminates the work or interrupts when an abnormality is detected according to the signals Sc, Sd, Se from the evaluation device 24. Perform processing, etc.,
Each processing value is given to the controller 26, and the controller 26
The robot body 23 is controlled via the.

Here, the evaluation device 24 includes four extraction circuits (extraction means) 24a to 24d and three evaluation circuits (evaluation means) 24e to 24g. The four extraction circuits extract a specific signal component included in the force signal Sb.
The first extraction circuit 24a has a DC component S _DC (signal level flat).
Extracting the average), a second extraction circuit 24b is AC component S _LAC (signal very low frequency range (for example, several Hz order)
Mean levels) extracts the third extraction circuit 24c extracts the higher frequency range than (eg AC component S _HAC (vibration waveform of several tens Hz order)), the fourth extraction circuit 24d
Extracts an impulse component _SPLS (impulse waveform) . The three evaluation circuits analyze and evaluate each extracted component, and when a unique signal state corresponding to a work abnormality is found, a signal Sc representing the occurrence of an excessive frictional force from each of them,
A signal Sd indicating the detection of a defect in the surface finish and a signal Se indicating the detection of the protrusion are output.

FIG. 2 shows the position Sa of the hand 21 and the force signal Sb.
6 is a graph showing the relationship of. Time t ₀Is below the hand 21
Fall start point, time t₁Starts inserting the part 20 into the hole
Point, time t_TwoIs the point where the bottom of the hole is reached (ie
End point). External force applied to the hand 21 immediately after insertion
It starts to increase, rises sharply at the end of work, and peaks
I can.

Here, several peculiar signal states are observed in the waveform of FIG. That is, (1) the average level of the signal
Point (average of signal level) is set to increase at time t ₁ later, (2) that the signal level of the increase is vibrating little by little, are observed sharp impulse waveform (3) signal halfway Is a point. Here, the average level of the signal
Is called a moving average.
Average of signal level over time. So the example
For example, by setting the unit time to several hundred ms, several Hz
It is possible to extract the AC component S _LAC in the low frequency range
Can, the DC component S _DC by a longer time unit
Can be extracted. Also, if it is vibrating here
Means that the signal level rises and falls as shown in (2) of FIG.
It means that it fluctuates. Therefore, the vibration waveform
Is a waveform in which the signal level fluctuates up and down.
U.

These unusual signal states are as follows: (1) the insertion friction of the component is large; (2) the surface finish of the component or the inner wall surface of the component insertion hole is rough; (3) the surface of the component or the inner wall surface of the component insertion hole. A typical cause is that there is a protrusion.

[0020] Therefore, the first evaluation circuit 24e, the DC component of the force signal Sb S _DC and AC components S _LAC, i.e. LSE
The average of the signal level of the signal Sb is evaluated , and (1) of the above-mentioned unique signal state is determined [determination signal Sc].

The second evaluation circuit 24f outputs the force signal S
b AC component S _HAC , that is, the vibration waveform of the force signal Sb,
Is evaluated to determine (2) of the above-mentioned unique signal states [judgment signal Sd].

Further, the third evaluation circuit 24g outputs an impulse component S _{PLS of} the force signal Sb, that is, an input signal Sb of the force signal Sb.
The amplitude of the impulse waveform is evaluated to determine (3) among the above-mentioned unique signal states [judgment signal Se]. With the above configuration, according to the present embodiment, various abnormal operations are detected from the state of the reaction force applied to the hand 21, and
Signals Sc, Sd and Se indicating respective abnormalities can be output. Therefore, when an abnormality occurs, the work can be interrupted by the computer 25 and necessary measures can be taken.

In FIG. 3, the position data Sa from the robot body 23 and the force signal Sb from the force sensor 22 are input to a force command circuit 30. The force command circuit 30 outputs the input force signal Sb with the passage of time (that is, the position data Sa).
Circuit 30a that develops a pattern in accordance with
An evaluation circuit 30b for comparing the current force signal Sb with a signal pattern in the storage circuit 30a to evaluate the degree of progress of the work by the hand 21, and a force command suitable for the progress stage of the work according to the evaluation result. A command value generation circuit 30c for selecting a value and outputting the selected value to the control device 26. A plurality of different command values are previously written in the command value generating circuit 30c by a computer.

FIG. 4A is a graph showing a change in the force signal Sb when a certain hand operation is performed. After the force signal increases with the change of the hand position and reaches a peak (e), it reverses and decreases (f), and then increases again to limit (g). Such a change in the force signal can be seen, for example, in the mating operation of the connector and the plug.

That is, in many connectors, the plug is pulled in by the receptacle itself of the connector during the fitting in order to increase the reliability of the fitting.

Therefore, a large force is required for the pressing force of the plug in the initial stage of the fitting, but it may be almost zero in the middle stage, and may be smaller in the final stage than in the initial stage.

In the above-described conventional example, the completion of the operation is determined when the force signal exceeds a predetermined detection level. The control target value in FIG. 4A has a magnitude corresponding to the detection level, and the force applied to the plug reaches the level of the control target value at the maximum.

However, as is apparent from FIG. 4 (a), the plug fitting operation is substantially completed at the point (P) at which the force signal rises sharply, and any further force application is useless. Not only that, but also unnecessary stress is applied to the plug and the connector, which is not preferable in terms of reliability. To improve this, the detection level (Fig. 4 (a)
It is conceivable that the control target value of
In this case, the force signal peak in the initial stage of the fitting exceeds the detection level, so that the completion of the work is erroneously determined.

Therefore, in the second embodiment, an optimum control target value is set in accordance with the operation stage, and unnecessary force (FIG. 4) is set.
(A) Refer to F). That is, since the temporal change pattern of the force signal is stored in the storage circuit 30a with the progress of the work, the work pattern (initial,
Middle or end).

Therefore, if a control target value for each work stage is set in advance, an optimum target value can be selected from the target values. For example, as shown in FIG. In the initial stage of the work requiring a relatively large fitting force, a large control target value (first target value) can be given to increase the pressing force of the hand 21, while at the end of the work requiring a relatively small fitting force, a small control target value is set. By giving the (second target value), the pressing force of the hand 21 can be reduced.

As a result, it is possible to avoid applying unnecessary force while preventing erroneous determination of work completion, and to improve reliability. Third Embodiment FIGS. 5 to 8 are views showing a third embodiment of the work evaluation device according to the present invention, which is an example applied to a keyboard depression test robot requiring delicate force adjustment.

In FIG. 5, reference numeral 40 denotes a keyboard to be tested; 41, a rod attached to a robot body 43 via a force sensor 42; Position data Sa indicating the tip position of the rod 41, a force signal Sb indicating the magnitude (and direction) of the force applied to the tip of the rod 41, and a key switch signal Sk of the keyboard 40 are all input to the evaluation unit 50.

The evaluation unit 50 analyzes the operation force pattern of the key switch for each of a plurality of items, and comprehensively evaluates the analysis result to determine the feeling of pressing the key switch more finely. The following are provided as components.

That is, a storage circuit 51 for storing a change pattern of the force signal Sb in accordance with the movement of the rod 41, a predetermined portion (A, B, C, D, E, F of this pattern signal, Window circuit 52, A, which cuts out (described later)
A first evaluation circuit 53 that evaluates the pressing force of the portion, a second evaluation circuit 54 that evaluates the pressing force of the portion B, a third evaluation circuit 55 that evaluates the pressing force of the portion C, and a third evaluation circuit that evaluates the pressing force of the portion D. A fourth evaluation circuit 56, a fifth evaluation circuit 57 for evaluating the waveforms of the E and F portions, a sixth evaluation circuit 58 for evaluating the pressing force drop of the E portion, and a seventh evaluation circuit 5 for evaluating the pressing force drop of the F portion
9, an eighth evaluation circuit 60 for evaluating the difference (A-B) between the pressing force of the part A and the part B, and the difference (C-
A ninth evaluation circuit 61 for evaluating D), and a judgment circuit 62 for collecting evaluation results of these evaluation circuits and making a comprehensive judgment on keyboard pressing characteristics.

FIG. 6 shows a conventional keyboard press test method. The figure shows typical switch characteristics. The switch pressing force increases as the rod position decreases, and at a certain point (P ₁ ), the switch changes from OFF (OFF) to (ON) (pressing force Step change). Furthermore, with increasing rod position pressing force is reduced, the switch at the point P ₂ with another has changed from ON to OFF. The operation feeling of the switch is generally expressed by (1) clarity of ON / OFF and (2) moderate lightness of key touch. (1) depends on the slope of the step waveform at the time of the ON-> OFF change. If the slope is gentle, the on / off change is difficult to sense. On the other hand, (2) depends on the change characteristic of the pressing force in the vicinity of the lower limit and the upper limit of the rod. This will be described with reference to FIG. FIG. 7A is a characteristic diagram in which a key touch is felt lightly.
On the other hand, FIG. 7B is a characteristic diagram that feels heavy. Comparing the two figures, the opening widths of the points P _A and P _B near the rising limit of the rod and the opening widths of the points P _C and P _D near the lowering limit are almost ideal zero in FIG. On the other hand, in FIG. 7B, which is felt heavy, it is considerably large.

In order to more precisely determine the feeling of pressing the key switch, it is necessary to constantly determine the above two check points, that is, clearness of ON / OFF and lightness of key touch. However, according to the conventional example of FIG. 6, if the only measurement area indicated by the broken line is opened and the off → on change point P ₁ exists in that area,
The test passed the test, and was far from the actual operational feeling.

On the other hand, in the third embodiment, as shown in FIG. 8, the signal patterns of the pressing force are A, B, C, D,
It is possible to cut out portions E and F (the cutout center is shown except for E and F in the figure), and it is possible to evaluate the pressing characteristics of these portions.

Therefore, in addition to the conventional evaluation items,
The on / off clarity can be determined from the inclination of the E and F portions,
The lightness of key touch can be determined from the separation width between A and B and between C and D.

As a result, the pressing feeling of the key switch can be determined more finely and constantly in accordance with the operation feeling actually experienced, and the inspection accuracy can be remarkably improved.

[0040]

According to the present invention, the external force acting on the hand is detected, the magnitude of the external force is compared with a predetermined reference value, the hand operation is evaluated, and the external force is analyzed. Since the evaluation of the hand work is performed based on the result, it is possible to provide a work evaluation device capable of determining an abnormality during the hand work.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a force signal waveform diagram of the first embodiment.

FIG. 3 is a configuration diagram of a second embodiment.

FIG. 4 is a force signal waveform diagram when the second embodiment is not applied and a force signal waveform diagram when the second embodiment is applied.

FIG. 5 is a configuration diagram of a third embodiment.

FIG. 6 is a force signal waveform diagram for explaining the clarity of on / off.

FIG. 7 is a force signal waveform diagram for explaining lightness of key touch.

FIG. 8 is a force signal waveform diagram of the third embodiment.

FIG. 9 is a configuration diagram of a conventional example.

FIG. 10 is a configuration diagram of a main part of a conventional example.

FIG. 11 is a force signal waveform diagram of a conventional example.

[Explanation of symbols]

21: Hand 24: Evaluation device 30: Force command circuit 50: Evaluation unit

────────────────────────────────────────────────── (5) References JP-A-2-160492 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B25J 13/08 B05B 19/18 B23P 19 / 02

Claims (1)

(57) [Claims] An external force detecting means for detecting an external force acting on a hand gripping a component during a predetermined operation ; an average of signal levels from a signal representing the detected external force ;
Extracting means for extracting a vibration waveform and an impulse waveform ; an average of the signal levels; an amplitude of the vibration waveform;
An evaluation means for comparing and analyzing the time-series change pattern and a predetermined reference value for the amplitude of the impulse waveform, and determining and evaluating an abnormality in the hand work and an abnormality in the part shape based on the analysis result, based on the evaluation result Control means for controlling continuation and interruption of the hand work.