JPS6071182A - Method of discriminating direction of work - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention A. Field of Industrial Application The present invention provides a method for determining the direction of the workpiece from the opening/closing amount of these gripping claws when the gripping claws of a gripping mechanism provided on an industrial robot etc. grasp a predetermined workpiece. This relates to a method for discriminating.

For example, as a specific example of a gripping mechanism provided in an industrial robot, etc., as shown in FIG. There are gripping claws (2) (2) that protrude so that they can be opened and closed.
A DC servo motor and an air cylinder are used as the driving source.

By the way, when the workpieces are sequentially transferred from process to process by the gripping mechanism, it is necessary that the workpieces are arranged in a predetermined orientation, and if there are workpieces arranged in different orientations, A situation may arise in which the work cannot be processed in the next step.

For example, in Fig. 2, the workpieces (3a), (3b), and (3c) aligned in the same direction are held by the closing operation of the gripping claws (2) and (2) and sent to the next process (A) one after another. ,
Works placed in a different direction from these works (3D
), it must be sent to the next step (B), which is different from the above next step (A).

That is, when holding a workpiece with a gripping mechanism, it is necessary to recognize the position, direction, etc. of the workpiece and control the gripping mechanism accordingly.

Conventionally, for such job control, the position, direction, etc. of a workpiece have been detected by a visual sensor or the like and recognized by image processing.

However, when using a visual sensor or the like to recognize the position, direction, etc. of the workpiece, a detection means such as the visual sensor must be added to the gripping mechanism, which complicates the configuration of the device and increases costs accordingly. There was also the problem that the cost was also high.

An object of the present invention is to provide a method for recognizing the direction of a workpiece without providing a detection means such as a visual sensor when the workpiece is held by a gripping mechanism and transferred from process to process. be.

29 Structure of the Invention The method for determining the direction of a workpiece according to the present invention electrically detects the opening/closing amount of the gripping claws (2) when the workpiece is clamped by a gripping mechanism consisting of a plurality of opposing gripping claws (2). death,
After shaping the waveform of the detection signal, the direction of opening/closing of the gripping claws and the amount of opening/closing are discriminated from the detection signal and an output signal is selectively sent out to discriminate the direction of the workpiece. do.

E. Embodiment An embodiment of the workpiece direction discrimination method according to the present invention will be described with reference to the block diagram shown in FIG.

In the figure, (4) is a rotary encoder that electrically detects the linear momentum caused by opening and closing of the gripping claws (2) (2). That is, for example, as shown in FIG.
There is a rack (5) on each arm side (front side in the figure) of (2).
(5) are respectively fixed, and a pinion (6) that simultaneously meshes with each of the two racks (5) (5) is sandwiched between them. By connecting the pinion (6) coaxially with the rotary encoder (4), the gripping claws (2) (2)
The linear momentum of the rotary encoder (4) is converted into the rotation amount of the rotary encoder (4), which is further converted into a detection signal in the rotary encoder (4). (7) is a waveform shaping circuit that inputs the detection signal output from the rotary encoder (4), shapes the waveform, and outputs it; (8) is connected to the waveform shaping circuit (7), and the output signal is Gripping claws (2
)(2) is a direction discrimination circuit that discriminates the opening/closing direction of (2).
9) is a counting circuit that counts the amount of rotation of the rotary encoder (4), that is, the opening/closing claw (2) of the gripping claw (2) (2).
(2) This is a circuit that detects the opening/closing amount. Here, the opening/closing amount of the gripping claws (2) (2) corresponding to a predetermined workpiece size is set in advance in the count circuit (9), and this setting amount is determined in consideration of the error range of the workpiece size, as shown in FIG. As shown in , the upper limit value and lower limit value are determined by the upper limit value (10) and the lower limit preset (11). Then, an OK or NG signal is selectively output from the count circuit (9) depending on whether the detected opening/closing amount is between the upper limit value and the lower limit value.

Based on this configuration, the operation of the above embodiment of the present invention will be described as follows. For example, as shown in Figure 2, workpieces (3a) (3b) arranged in a certain direction
It is assumed that the gripping direction of the gripping claws (2) (2) is constant in a state in which the workpiece (3C) and the workpiece (3d) arranged in a different direction from these workpieces coexist. Also, work (3a) (
3b) It is assumed that the upper limit (10) and the lower limit (11) in FIG. 3 are set corresponding to the dimension (1) in (3c).

When the gripping claws (2) (2) are driven in the direction of opening, the direction and amount of opening are determined by the rotary encoder (4), the waveform shaping circuit (7), the direction discrimination circuit (8), and the counting circuit (9).
) is detected. Next, hold the gripping claws (2) (2)
is moved toward the workpiece by a predetermined amount and then driven in the closing direction to grip the workpiece (3a), for example, and the distance (A) between the gripping claws (2) (2) corresponding to the workpiece method (l) is detected. When the workpiece (3b) (3c) is pinched, the OK signal is output in the same way, but the workpiece (3d)
When the workpiece is clamped, the detected distance (m) between the gripping claws (2) (2) does not match the workpiece size (β), so an NG signal is output.

Immediately, in the case of Figure 2, when the OK double signal is output, the workpiece is transferred to the process (
A), and when the NG signal is output, the work is sent to process (B).
), and the direction of the workpiece is determined and taken out based on the distance detected by the gripping claws (2) (2).

In the above embodiment, the workpiece is held by a gripping mechanism consisting of two gripping claws, but the present invention is not limited to this, and the workpiece may be held by a gripping mechanism consisting of three or four gripping claws. is also applicable.

Effects of the Invention According to the present invention, when a workpiece is gripped by a gripping mechanism such as a robot, the interval between the gripping claws when the workpiece is gripped is detected. Due to the difference in size, it is possible to distinguish and take out only workpieces in a predetermined direction, and job control can be performed without providing an external device such as a visual sensor to recognize the direction of the workpieces. Further, it becomes possible to distinguish and take out only a predetermined workpiece based on the difference in size from a state in which different types of workpieces coexist, thereby increasing the flexibility of the gripping mechanism of a robot or the like.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a workpiece gripping mechanism of a robot, etc., Fig. 2 is a schematic diagram of the operation of the workpiece gripping mechanism without sending workpieces placed in different directions to different processes, and Fig. 3 is a diagram of the present invention. FIG. 4 is a block diagram of an embodiment of the method for determining the direction of a workpiece according to the present invention; FIG. be. (2) (2) - Gripping claw, (4) - Rotary encoder, (7) - Waveform shaping circuit, (8') - Opening/closing direction discrimination circuit, (9) - Rotation amount counting circuit.

Claims (1)

[Claims] (1) When a workpiece is held by a gripping mechanism consisting of a plurality of opposing gripping claws, the opening/closing amount of the gripping claws is electrically detected, and after waveform shaping of the detection signal, the opening/closing direction and opening/closing amount of the gripping claws are determined. A method for discriminating the direction of a workpiece, characterized in that the direction of the workpiece is discriminated by making a determination based on the detection signal and selectively sending out an output signal.