JPS6149075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Industrial Field of Application) The present invention relates to an assembly robot, and more particularly to a memory and replay type assembly robot having an articulated operating arm and a vertical axis.

(Conventional technology) Currently, robots are being adopted to cope with the automation of factory production. One of the work processes of this automation is automatic assembly work.

Incidentally, the basis of automatic assembly work is the fitting work between shafts and holes, and assembly robots are used to automatically perform this fitting work. An example of such an assembly robot is the Japanese Patent Laid-open Publication No. 49
A reaction force detection device described in JP-A-113366 is known.

Next, the assembly robot described in the above publication will be explained with reference to FIG. In the figure, the positioning mechanism section 23 includes step motors 23X, 23Y, and 23Z for driving the drive shaft 23a in the X direction, Y direction, and Z direction, respectively. These step motors 23X, 23Y, 23Z are controlled by outputs from respective control circuits 25X, 25Y, 25Z. In this example, drive shaft 2
3a is driven according to an X, Y, Z orthogonal coordinate system. The holding mechanism section 22 has fingers 2 that grip the fitting object 21.
2b, and a flat plate 22a to which the finger 22b is fixed. Further, the flat plate 22a and the drive shaft 23a are coupled by a cross-shaped leaf spring 24, and a strain meter element 26 is mounted on the surface of the leaf spring 24. At the four corners of a flat plate 29 fixed to the drive shaft 23a, rod-shaped members 28 are attached to the flat plate 22a.
It is provided so as to be inserted into through holes 22c provided at the four corners of. Further, a spring 27 is provided around the rod-shaped member 28 so as to surround it. A microswitch 30 is attached to the position of each through hole 22c on the lower surface of the flat plate 22a, and is operated by the tip of the rod-shaped member 28.

When the fitting object 21 and the target object 20 are not in contact with each other, the holding mechanism section 22 is suspended from the drive shaft 23a of the positioning mechanism section 23 by four leaf springs 24. When the object 21 is gradually lowered by the shaft servo motor 23Z and comes into contact with the object 20, the springs 24 and 27 begin to contract. In this state, a signal is generated from the strain meter element 26, allowing the relative positional relationship and deflection between the positioning mechanism section 23 and the holding mechanism section 22 to be known. Further, when the Z-axis step motor 23Z is driven to further lower the drive shaft 23a, the tip of the rod-shaped member 28 comes into contact with the micro switch 30, which is activated. Therefore, if the drive of the Z-axis step motor 23Z is controlled by the output signal of this microswitch 30, it is possible to prevent excessive pressing force from being applied between the objects 20 and 21.

Next, the operation of the conventional reaction force detection device described above will be explained.

First, after the fitting object 21 is grasped by the holding mechanism section 22, it is placed at a specific position outside the range of the expected variation in the center position of the hole 20a.
In the next step, the mating object 2 is
1 in the direction of the center of the hole 20a while applying a certain amount of pressing force in the (-Z) direction.
to move. As described above, the positioning mechanism section 23 and the holding mechanism section 22 are coupled via the elastic support 24, so when the drive shaft 23a is moved in the X direction in the figure, the mating object 21 is pressed in an inclined position. I was dragged along. And hole 20a
When the fitting object 21 comes to the vicinity of the center position, its tip portion is dragged into the hole 20a by the spring force of the elastic support 24, and the fitting object 21 and the hole 20a are roughly aligned.

Furthermore, in the next step, the positioning mechanism section 2
Correcting operations of the drive shaft 23a in the X direction and the Y direction are performed so that the drive shaft 23a in FIG. 3 and the axis of the fitting object 21 coincide with each other. Thereafter, force is gradually applied downward (-Z direction) to the fitting object 21, and the fitting object 21 is gradually inserted into the hole 20a of the target object 20 while repeating the above correction operation as necessary.
If more force than necessary is applied to the fitting object 21 in the incomplete state during this insertion, the fitting object 21 becomes stuck and cannot be inserted. Furthermore, there is a possibility that the object 21 or 20 may be destroyed. To prevent this,
For example, the elastic support 24 detects a reaction force from the target object 20, and when the reaction force exceeds a certain value, the downward pressing force is weakened, and the axis of the drive shaft 23a and the fitting object 21 is aligned again. Corrective actions are taken to achieve a match. While repeating such operations, the fitting object 21 is inserted into the target hole 20a.

As can be seen from the above explanation, the conventional reaction force detection device described above is provided with a sensor mechanism for detecting reaction forces in the X, Y, and Z directions between the object holding function and the drive shaft. The output signal from the sensor controls the drive shaft to insert the shaft into the hole. Therefore, using this reaction force sensing device, it is possible to perform charging with micron precision, but it requires a special sensor to ensure that the tool matches the hole, which prevents the reaction force from being charged. There were problems in that the force detection device itself was complicated and the assembly work speed was slow.

Furthermore, conventional teaching methods for memory/reproduction type assembly robots can be roughly divided into two methods: one in which the operating arm of the robot is moved manually along the trajectory of the actual object, or the other is moved using a master rave method, and the operating procedures are stored in a memory device. There is a numerical control method that calculates the movement of the robot's actuating arm and then stores the operating procedure.

However, with either teaching method, the robot must perform movements in three-dimensional directions, and for this purpose, the teaching method must be such that the amount of displacement in each axial direction can be accurately memorized and reproduced.

However, most of the articulated robots that have been widely used as industrial robots have a multi-joint arm in the robot body that can move in three axes (X, Y, and Z axes).
The wrist part consists of jigs and tools such as grips attached to the tip of the robot body, and has three degrees of freedom in the O, Y, and Z axes, for a total of 6 degrees of freedom. It consists of degrees of freedom. For this reason, conventional articulated industrial robots are capable of teaching using the tracing method, but teaching using the numerical control method requires a large memory capacity to deal with complex arithmetic expressions such as 6-element, 6-dimensional equations. Teaching was impossible.

(Problems to be Solved by the Invention) As explained above, conventional assembly robots have complicated mechanisms for controlling the positions of objects, have slow working speeds, and have enormous difficulty in teaching using numerical control methods. There was a problem in that a control device with storage capacity was required.

The present invention has been made in view of the above circumstances, and its purpose is to have a multi-joint actuating arm part that allows relatively flexible work, and to facilitate teaching using copy teaching methods and numerical control methods. To provide a small memory/reproduction type assembly robot which can be easily configured, has a high working speed, and has a wide range of motion.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the memory/reproduction type assembly robot according to the present invention includes a support body and a plurality of robots sequentially attached to the support body so as to be horizontally rotatable. A multi-joint actuating arm configured by an arm, a vertical shaft attached to the tip of the multi-joint actuating arm, and a lower end of the vertical shaft capable of lifting, lowering, rotating or horizontally controlling the vertical axis. and a gripping device attached to the gripping device, and is configured such that the horizontal flexibility of the multi-joint operating arm portion and the vertical shaft is sufficiently larger than the vertical flexibility with respect to external force applied to the gripping device.

(Function) According to the memory/reproduction type assembly robot of the present invention, the multi-joint actuating arm portion and the vertical shaft have selective flexibility such that they move strongly in the vertical direction and move softly in the horizontal direction, thereby facilitating the assembly process. This makes positioning easier during mating work, which is a typical work, so it can be used for inserting and press-fitting parts into holes in objects with less twisting. It is also possible to perform screw tightening work in conjunction with a tool device. Furthermore, since simple calculations are required, teaching using a numerical control method is possible and the calculation speed can be improved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view of an embodiment of the present invention, and as shown in the figure, the robot has a first horizontal arm 3 attached to a turning disk 2 of a pedestal 1, which is a support, by an actuator (not shown). The base end of the first horizontal arm 3 is pivotally mounted so as to be horizontally pivotable, and a second horizontal arm 4, which is also pivotable horizontally by an actuator (not shown), is pivotally attached to the distal end of the first horizontal arm 3. has been done. As a result, the first and second horizontal arms 3 and 4 each take a bent shape by turning. Further, a front-facing arm 5 is pivotally attached to the tip of the second horizontal arm 4. This front-facing arm 5 includes first and second horizontal arms 3,
Link mechanisms 7 and 8 are attached to the first and second horizontal arms 3 and 4 so that the robot rotates horizontally and maintains the front direction of the robot, that is, parallel to the Y axis, no matter how the robot rotates or bends. .

In this way, the first and second horizontal arms 3, 4 and the front-facing arm 5 are connected to form a multi-joint operating arm section 6 that pivots only in the horizontal direction.

Further, as shown in the side view of FIG. 2, a gripping tool 11 is suspended from a vertical cylinder 9, which is a vertical shaft, at the distal end of the multi-joint operating arm section 6. This gripping tool 11 is configured to be horizontally turned by a horizontal turning motor 12 and to change the direction of the tip of the gripping tool 11 by a torsion turning motor 13. The vertical cylinder 9 that suspends the gripping tool 11 is used to move vertically parallel to the Z-axis by telescopic operation. Note 10
is a weight balance spring.

X as robot 3-axis movement of X, Y, and Z axes
Regarding the axis (horizontal direction) and the Y-axis (front-back direction), the horizontal rotation movement using the respective base points O ₁ and O ₂ of the first and second horizontal arms 3 and 4 as the fulcrum and the base point O ₄ of the gripping tool 11 are performed. This is performed by a horizontal turning operation using a fulcrum, and the Z-axis (vertical direction) is performed by raising and lowering a vertical cylinder 9 that suspends the gripping tool 11. This displacement in the Z-axis direction can be achieved by moving the first horizontal arm 3 up and down on the turning disc 2 during initial rough positioning and assembly work, as the stroke range is not large during assembly work. It is possible to carry out a wider range of movement in the Z-axis direction by incorporating an elevating device for movement.

Next, first, the assembly work by the memory/reproduction type assembly robot of this embodiment will be explained.

Multi-joint operating arm section 6 that rotates only in the horizontal direction
is composed of a first horizontal arm 3, a second horizontal arm 4, and a front-facing arm 5. A vertical cylinder 9 equipped with a gripper 11 and capable of moving up and down is attached to the tip of the multi-joint arm 6. Furthermore, a turning motor 12 for horizontally turning the gripping tool 11 is provided.

In this embodiment, even when the first horizontal arm 3 and the second horizontal arm 4 turn, the front-facing arm 5 maintains a constant posture of the part (not shown) gripped by the gripper 11, and as a result, Parts can be moved in parallel to any position without being rotated. In addition, the gripping tool 11
By rotating the gripper 11 by a predetermined angle using the horizontal turning motor 12, the gripping tool 11 can be rotated by an arbitrary angle around the Z axis to control the posture of the component.

In addition, when inserting a component into a hole where it is not necessary to maintain a constant posture of the component, or tightening a screw, the vertical cylinder 9 equipped with the gripping tool 11 is moved to the second position.
It may also be attached to the tip of the horizontal arm 4.

In the assembly robot of this embodiment, when a force is applied in the Z-axis direction, it is strong against external force, so the tip of the gripper 11 hardly displaces, whereas when an external force is applied in the X-axis direction or Y-axis direction, Because it has selective softness, it moves softly when force is applied to it, so even a small amount of force causes it to be displaced laterally by a relatively large distance. Therefore, for example, when inserting a component into a hole, even if the position of the article does not match the hole accurately and misalignment occurs, if the component hits the entrance of the hole and receives an external force, the multi-joint operating arm 6 is displaced only in the horizontal direction by the horizontal component of the external force so that the part and the hole align, allowing the part to be inserted into the hole accurately and quickly. The same applies to moments, and as a result, it is possible to perform operations with less strain when inserting parts into holes, press-fitting, etc., and the efficiency of assembly operations can be greatly improved.

Furthermore, if the Z-axis is taken in the direction of gravity, this direction is strong against external force, so deformation of the multi-joint operating arm section 6 due to the weight of the handled parts is so small that it hardly poses a problem. As a result, there is no need to perform control that takes into account the deformation of the multi-joint operating arm section 6, and the method of controlling the assembly robot can be further simplified.

Next, teaching by numerical control of the assembly robot of this embodiment will be explained.

The length of the first horizontal arm 3 is R ₁ , the length of the second horizontal arm 4 is R ₂ , and the length of the front-facing arm 5 is
R ₃ and the length of the gripper 11 is R ₄ , and the distances of the respective arms and grippers in the X-axis direction are A ₁ , A ₂ , A ₄ (the front-facing arm 5 is parallel to the Y-axis). Therefore, the distance in the X-axis direction is O), and the distance in the Y-axis direction is B ₁ , B ₂ , B ₃ , and B ₄ . Of these X and Y-axis distances, A ₄ , B ₃ , and B ₄ are the gripping distances. Ingredients 1
Since it is based on the rotation angle (γ) of 1 and the front-facing arm 5, by calculating only the displacements A ₁ , A ₂ , B ₁ , and B ₂ , the base point of the robot can be determined with a simple calculation formula.
The distance (x) in the X-axis direction and the distance (y) in the Y-axis direction from O ₁ to the tip of the gripping tool 11 can be determined using the following formulas.

That is, x=R ₁ cosα−R ₂ cosβ+X ₁ y=R ₁ sinα+R ₂ sinβ+Y ₁ However, X ₁ =A ₄ , Y ₁ =B ₃ +B ₄ .

The turning angles (α) and (β) formed by the first and second horizontal arms 3 and 4 can be calculated using the above equations regarding x and y.

Therefore, displacement settings in the X-axis and Y-axis directions can be expressed by extremely simple equations, and numerical control can be easily performed. That is, during teaching, displacement settings in the X, Y, and Z axis directions are performed by calculation, and then (x ₁ , y ₁ , z ₁ ), (x ₂ , y ² ,
This is done by sequentially storing the commands z ₂ )...(xn, yn, zn). Thermal distortion and assembly errors can be reduced (α) and (β) by installing the sensor as necessary.
This is done by modifying the angle and the vertical movement of the vertical cylinder 9.

Of course, in the case of manual tracing teaching, it can be carried out by manually rotating the locus of a predetermined object using a teaching roller type, similar to known robots.

Master-slave teaching, which is a form of copy teaching, is also possible, in which a sensor is attached to the tip of the gripper, a delay device is attached between the master and the robot body, and the vertical cylinder of the master is raised. Lower the cylinder to a predetermined position on the top surface of the drawing board, etc., and
This is done by determining the starting point of the Y-axis and teaching on the drawing, and on the other hand, the robot body is made to perform a copying operation of the actual object at a predetermined delay speed while feeding back sensor signals.

As mentioned above, in the memory/reproduction type assembly robot of this embodiment, the displacement setting by the multi-joint operating arm can be expressed by a simple calculation formula using the X and Y components, which are horizontal planes, so it is possible to use the numerical control method. This makes teaching possible, simplifies the control of the robot and its associated configuration, significantly improves the calculation speed, and helps reduce storage capacity.

〔Effect of the invention〕

As explained above, according to the memory/reproduction type assembly robot of the present invention, the holding mechanism portion of the gripping device is composed of a multi-joint actuating arm portion whose softness is directional in response to an external force applied to the gripping device, and a vertical Since it is constructed with a shaft, it is possible to have a simple construction and to passively and quickly correct the assembly work with less twisting. In addition, since the gripping device can be controlled to move up and down, rotate, or horizontally swivel, combined with the multi-joint operating arm, the work area is wider and a variety of applied movements are possible compared to conventional Cartesian or polar coordinate robots. do. Furthermore, it simplifies the control of the robot and the associated configuration, enables teaching using a numerical control method, improves calculation speed, and helps reduce storage capacity, among other excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an assembly robot according to an embodiment of the present invention, FIG. 2 is a side view of the same, and FIG. 3 is a perspective view of a conventional assembly robot. 2...Turning disk, 3...First horizontal arm, 4...Second horizontal arm, 5...Front-facing arm, 6...Multi-joint operating arm section, 9...Vertical cylinder, 11...Gripper, 12...Horizontal turning motor, 13...Torsional turning motor.

Claims (1)

[Scope of Claims] 1. A support body, a multi-joint actuation arm portion constituted by a plurality of arms sequentially attached to the support body so as to be able to rotate in a horizontal direction, and a multi-joint actuation arm portion attached to the distal end portion of the multi-joint actuation arm portion. a vertical shaft; and a gripping device attached to the lower end of the vertical shaft so as to be able to control elevation, rotation, or horizontal rotation via the vertical shaft; A memory/reproduction type assembly robot characterized in that the arm part and the vertical axis are configured such that the horizontal softness is greater than the vertical softness. 2. The multi-joint actuating arm section is composed of three or more arms, and the most advanced arm among these arms is a front-facing arm that rotates and maintains the front position of the robot regardless of whether the other arms rotate or bend. A memory/reproduction type assembly robot according to claim 1, characterized in that: