JPS6288589A - Robot - 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] [Technical field of invention] The present invention relates to a robot having position correction means.

[Technical background of the invention and its problems]

With the development of high-mix, low-volume production, assembly systems using robots are rapidly becoming popular.

Generally, in this assembly system, the workpieces to be assembled are transported by a jig pallet attached to an index table or a free flow conveyor with a single positioning mechanism, while the workpiece is conveyed by a robot of an articulated type such as a scalar type or a rectangular coordinate type. A grip, a screw tightening machine, etc. are attached to the head of the assembly, and a member is assembled into the workpiece to be assembled, inserted, screwed, or adhesive is dispensed.

A normal robot assembly system is configured as described above, but if a particularly high degree of positional accuracy is required, a visual sensor such as an ITV camera is attached to the robot's head, and the information obtained from this visual sensor is transmitted to the robot. The data is sent to a control unit that controls the robot's motion, where it is processed and the robot's motion is corrected based on the results.

However, position correction methods using such visual sensors cannot be processed by general-purpose robots.

Extensive controls are required and are too expensive for conventional assembly systems. Furthermore, even if a visual sensor is to be attached, the workpiece to be assembled generally has a complex shape in many cases, and such a workpiece requires a plurality of visual sensors.

Problems such as its installation and slow calculation processing speed arise.
There are limited cases where it can be put to practical use.

However, on the other hand, the number of cases in which high-level position correction is required is increasing, and there is a demand for something that can easily and inexpensively perform the required position correction using a normal robot.

[Purpose of the invention]

The object of the present invention is to configure a robot that detects the position of a workpiece to be assembled by means other than a visual sensor and automatically performs a high-level position correction operation.

[Summary of the invention]

The head of the robot body is equipped with a work chuck.
A detection head consisting of a plurality of touch sensors whose contact part with the workpiece is set back by a certain amount is installed, and on the other hand, when the plurality of touch sensors come into contact with the workpiece, the control surface that controls the operation of the robot body is installed. Means for determining the positional state pattern of the workpiece from the on/off state of each touch sensor that occurs, and the positional state of all the on/off states of the plurality of touch sensors caused by the positional shift of the workpiece that may actually occur. Corresponding to the pattern
Means for selecting an operation program corresponding to the determined positional state pattern from operation programs for the robot body taught and registered in advance, and controlling the operation of the robot body according to the operation program to move the head section. By providing this, the configuration is such that position correction can be performed without using a visual sensor.

[Embodiments of the invention]

Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

FIG. 1 shows the configuration of an assembly system using a robot which is an embodiment of the present invention. In this assembly system, the work to be assembled (V) is mounted on a jig pallet (V) attached to a free flow conveyor (1). 2) is loaded and transported,
It locks onto a stopper (3) attached to the side of the conveyor and stops at a fixed position on the assembly stage.

In this assembly stage, the robot that assembles the member (P) to the workpiece to be assembled m is a Cartesian coordinate type robot, and its main body is a chuck (5) that grips the member CP).
) is provided with a head part (6), and this head part (6)
a Z-axis direction drive mechanism (7) that moves this Z-axis direction drive mechanism (7) in the X-axis direction; an X-axis direction drive mechanism (8) that moves this Z-axis direction drive mechanism (7) in the X-axis direction; 8) in the Y-axis direction, and is attached to the frame (11) via a support (10) provided on the YIliIh-direction drive mechanism (9). There is. Further, the head section (6) has a rotating shaft (13) extending in the Z-axis direction that is rotationally driven by a drive device (12) attached to the Z-axis direction drive mechanism (7), and has a rotating shaft (13) that extends in the Z-axis direction. 5) is supported on one end of a support plate (14) attached perpendicularly to the tip of the rotating shaft (13). Further, a detection head (15) for position correction described below is attached to the other end of the support plate (14).

'The detection head (15), as shown in FIG.
(18c), and each touch sensor (18a) to (1
8c), the contact portion (19) at the tip that contacts the workpiece is retracted by a certain amount S following the step of the base plate (17).

This detection head (15) is attached rotationally symmetrically to both ends of a rod-shaped detection head fixing block (19) so that the touch sensor (18c) whose contact part is furthest back is on the inside. (19) is attached perpendicularly to the support plate (14).

Note that each touch sensor (18a) of this detection head (I5)
”) to (18c) are sent to a control unit (not shown) that controls the operation of each part of the robot body.

Note that (20) shown in Fig. 1 is the workpiece to be assembled (W
) This is a stocker for members (P) to be assembled into.

Next, the operation of assembling parts of the robot will be described.

As shown in Figure 1, the workpiece to be assembled is.

It is assumed that a complex-shaped top surface is formed on the top of a cube, and the side surfaces of the cube can be used as reference surfaces. In normal assembly work, when mounting the component on the workpiece (W) to be assembled, it is assumed that the positional accuracy of the part (22) is within the tolerance range required for mounting the component (CP), and the chuck ( 5) to the specified position and assemble it, but the pallet (2) on the conveyor (1)
) If the shape accuracy of the workpiece (1, 1) to be assembled is not very high, or if particularly high-precision positioning is required to assemble the part (P), it may not be possible to assemble it as is. It happens.

Therefore, this robot moves to the pre-taught position and moves the stocker (20) by the chuck (5).
) After gripping the member (P) positioned and held at the fixed position, as shown in FIG. Move it to the pre-taught position,
The workpiece to be assembled is positioned and fixed on this assembly stage (
The detection head (15) is brought into contact with the basic surface of the workpiece (W) to detect the positional deviation of the workpiece (W) to be assembled. The above detection head (
15) contact is with the − reference surface (23) of the workpiece to be assembled (W).
) and the adjacent reference plane (2) perpendicular to this − reference plane (23).
4) will be carried out.

By the way, the teaching of the detection head (15) is
As shown in FIG. 4, the six touch sensors (
Among 18a) to (18c), the outer two sensors (18a,) at the most advanced position contact and turn on (ON), and the other four sensors (18b)
,).

If (18b,), (18ci), and (18c,) are turned off without contact, for example, as shown in FIG. 5, the workpiece to be assembled (W) is indicated by the broken line The sensor (18a, ), (18at)
(tgbz) turns on when touched, other sensor (18b1)
, (18cm), (18c,) are turned off without contact, it means that the workpiece to be assembled has a rotational deviation Δy of one sensor from the correct position. In addition, when the detection head (15) is brought into contact with the reference surface (24), the sensor (18a,
, (18a,), (18b,) are on, other sensors (t
Since gbxL(taciL(tact)) is turned off, it is detected that a rotational deviation ΔX of one sensor has occurred with respect to the correct position.

Furthermore, in the example shown in FIG. 6, with respect to the reference plane (23),
Sensor (18aW, (18az), (18b1), (1
8bz) is touched and turned on, other sensors (18cj, (1
8c2) is turned off, and the sensor (18a,), (18a,) is in contact with the base surface (24) and turned on, and the other sensor (18b) is turned off (tabzL(18cz)-(1
8ca) is off, it is detected that there is a deviation of Δy only in the Y-axis direction.

Therefore, in advance to the control part of the robot.

Positioning points corresponding to all on/off state position patterns of the six touch sensors (18a) to (18c) that constitute the detection head (15) caused by positional deviation of the work to be assembled (W) that may actually occur. If you teach and register the above reference plane (23), (
24), the destination point of the chuck (5) can be determined from this information, and the member (P) can be moved to the workpiece (V) that is misaligned in various ways. ) can be assembled correctly.

As described above, the detection head (15) is composed of a plurality of touch sensors (18a) to (18c) whose contact parts with the workpiece are shifted by a certain amount, and this is attached to the head part (6) of the robot body. If you install it and perform position correction, the control unit of the general-purpose robot can process the position deviation correction, and the workpiece to be assembled (υ) that is misaligned in various ways can be processed.
It is possible to take necessary position correction operations for the position. Moreover, this position correction method does not require complicated coordinate calculations in the control unit, and requires multiple touch sensors (18a) to (
By simply processing the on/off pattern in step 18c), the robot can be operated by selecting a desired operation program from the robot main body operation programs that have been taught and registered in advance, resulting in fast operation.

Further, such a position correction means has the advantage that it can be used even when a visual sensor such as an ITV camera cannot be used effectively.

Next, other embodiments will be described.

In the above embodiment, the detection head is configured with three touch sensors attached to the base plate and placed at both ends of the fixed block, for a total of six touch sensors. The number and arrangement are determined by detection accuracy, shape and size of the workpiece to be assembled, etc.
The number and arrangement are not limited to the above.

Furthermore, in the above embodiment, a case has been described in which the detection head is moved to a pre-taught position point with respect to the workpiece to be assembled to detect positional deviation, but the positional deviation of the workpiece to be assembled is large and the touch sensor is If the stroke of the contact part is exceeded, it is sufficient to perform additional detection at a slightly distant position.

Furthermore, in the above embodiment, detection was performed on one reference plane and then the detection head was moved to another reference plane, but detection on the one reference plane described above can be sufficient for correction. In this case, or in cases where the detection result can be estimated without actually performing detection on other reference planes, detection on other reference planes may be omitted.

Furthermore, although the above embodiments have been described with respect to a Cartesian coordinate type robot, the position correction using this detection head can also be applied to other robots such as an articulated type robot.

〔Effect of the invention〕

The head of the robot body is equipped with a work chuck.
A detection head consisting of multiple touch sensors whose contact parts with the workpiece are shifted by a certain amount is installed, and the control unit is equipped with a detection head that detects the on/off state of each touch sensor that occurs when the multiple touch sensors come into contact with the workpiece. The means for determining the positional state pattern of the workpiece and the positional state pattern of all the on/off states of the plurality of touch sensors caused by actual positional deviation of the workpiece are taught and registered in advance. means for selecting an operation program corresponding to the determined positional state pattern from the operation programs for the robot body and controlling the operation of the robot body using the operation program to move the head part; It has become possible to perform high-level position correction using the control unit of a general-purpose robot without using a visual sensor, and it has also become possible to perform it at high speed.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of an assembly system using a robot according to an embodiment of the present invention, FIG. 2 is a perspective view showing the configuration of its detection head, and FIG. 3 is a perspective view showing the position of the work to be assembled and the detection head. A front view showing the relationship, FIG. 4 is a diagram showing the state of contact of the detection head with a correctly positioned work to be assembled, and FIGS. 5 and 6 show the state of contact of the detection head with a work to be assembled that is misaligned, respectively. It is a diagram.

Claims (1)

[Scope of Claims] A robot main body having a mechanism for moving a head section provided with a work chuck to an arbitrary position, a control section controlling the operation of the robot main body, and a plurality of robots sending detection signals to the control section. touch sensors, and a detection head attached to the head section by retracting the contact portions of the touch sensors with the workpiece by a certain amount, and the control section controls the touch sensors of the plurality of touch sensors. A means for determining the positional state pattern of the workpiece based on the on/off state caused by contact with the workpiece, and a positional state pattern of all the plurality of touch sensors in the on/off state caused by positional deviation of the workpiece that may actually occur. A motion program corresponding to the determined positional state pattern is selected from motion programs for the robot body that have been taught and registered in advance in accordance with the above, and the motion of the robot body is controlled by this motion program to control the head section. A robot characterized by having means for moving the robot.