JPH0314591B2 - - 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.

(Prior Art) Currently, with the automation of factory production, assembly robots have come into use. This assembly robot is used for fitting shafts and holes, which is one of the basic tasks in automatic assembly work. A conventional example of such an assembly robot is JP-A-49-
A reaction force detection device disclosed in Japanese Patent No. 113366 is known.

First, the configuration of the conventional reaction force detection device will be briefly explained with reference to FIG. 3.

In the same figure, the positioning mechanism section 23 is the drive shaft 2
Step motors 23X, 23Y, 23 for driving 3a in the X direction, Y direction, and Z direction, respectively.
Contains Z. These step motors 23
X, 23Y, 23Z are respective control circuits 25
Controlled by outputs from X, 25Y, and 25Z. In this example, the drive shaft 23a is driven according to an X, Y, Z orthogonal coordinate system. The holding mechanism section 22 includes a finger 22b that grips the fitting object 21, and a finger 22b that grips the fitting object 21.
It is composed of a flat plate 22a for fixing. Further, the flat plate 22a and the drive shaft 23a are coupled by a cross-shaped leaf spring 24.
A strain meter element 26 is mounted on the surface of the sensor. Rod-shaped members 28 are provided at the four corners of a flat plate 29 fixed to the drive shaft 23a so as to be inserted into through holes 22c provided at the four corners of the flat plate 22a.
Further, a spring 27 is provided around the rod-shaped member 28 so as to surround it. Flat plate 22a
A micro switch 30 is attached to the position of each through hole 22c on the lower surface of the holder, 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 assembly work using the reaction force detection device will be explained.

After the fitting object 21 is gripped 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, in this state, the drive shaft 23a is moved in the direction of the center position of the hole 20a while applying a certain amount of pressing force to the fitting object 21 in the (-Z) direction. Positioning mechanism section 23 and holding mechanism section 22
are connected to each other via the elastic support 24, so when the drive shaft 23a is moved in the X direction in the figure, the fitting object 21 is pushed and pulled in an inclined position. When the fitting object 21 comes near the center of the hole 20a, its tip is dragged into the hole 20a by the spring force of the elastic support 24, and the approximate positioning of the fitting object 21 and the hole 20a is achieved. It will be done.

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 20 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 will become stuck or become impossible to insert. Furthermore, there was a risk that either the fitting object 21 or the target object 20 would be damaged or destroyed. To prevent this, for example, the elastic support 24 detects the reaction force from the target object 20, and when this reaction force exceeds a certain value, the downward pressing force is weakened, and the drive shaft 23a and the fitting object are connected again. A correction operation is performed to align the axis with 21. While repeating such operations, the fitting object 21 is inserted into the target object 20a.

As can be seen from the above explanation, the conventional reaction force detection device used in assembly work is a sensor mechanism that detects the reaction force in the three axes of X, Y, and Z directions between the object holding function and the drive shaft. The drive shaft is controlled by the output signals of these sensors, and the shaft is inserted into the hole without twisting. 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 structure of the force detection device itself was complicated and the assembly work speed was slow.

In addition, most conventional articulated robots have a multi-jointed arm in the robot body that can move the three axes of X, Y, and Z.
It has three degrees of freedom in the axial direction, and is a wrist part consisting of a jig and tool attached to the tip of the robot body.It also has three degrees of freedom in the X, Y, and Z axes. It consists of 6 degrees of freedom. For this reason, conventional articulated robots are capable of teaching using the tracing method, but teaching based on numerical control requires a large memory capacity in order to deal with complex arithmetic expressions such as 6-element, 6-dimensional equations. is 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-mentioned circumstances, and its purpose is to have a multi-joint actuating arm portion that allows relatively flexible work, to facilitate teaching using copy teaching methods and numerical control methods, and to provide To provide a small memory/reproduction type assembly robot which is simple in configuration, 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 storage/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 portion constituted by an arm and having other arms positioned below the arm attached to the support; a vertical shaft attached to the tip of the multi-joint actuating arm portion; 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; It is characterized in that the softness in the horizontal direction is greater than the softness in the vertical direction.

(Function) According to the memory/reproduction type assembly robot of the present invention configured as described above, the multi-joint operating arm portion and the vertical axis have selective flexibility in that they move strongly in the vertical direction and move softly in the horizontal direction. Because it has a holder, positioning during assembly work is easy, so it can be used for inserting parts into holes in objects, press-fitting, etc. without damaging objects or holes, and it is also rotatable about the vertical axis. It is also possible to perform screw tightening work in conjunction with the device. Moreover, since it is horizontally pivotable and has a multi-joint operating arm portion in which other arms are disposed below the arm attached to the support, a wide range of motion can be obtained. It requires even simpler calculations, so
Teaching using a numerical control method becomes possible, and the calculation speed can be improved.

(Example) Embodiments 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 assembly robot is a support and a turning disk 2 of a pedestal 1 is connected to a first horizontal arm by an actuator (not shown). 3 is pivotally connected at its base end so as to be horizontally pivotable,
At the tip of the horizontal arm 3, a second horizontal arm 4, which can also be pivoted in the horizontal direction by an actuator (not shown), is pivotally attached to the lower side of the first horizontal arm 3. As a result, the first and second horizontal arms 3 and 4 have a bent shape due to their respective turns. Further, a front-facing arm 5 is pivotally attached to the tip of the second horizontal arm 4. This front-facing arm 5 rotates horizontally and maintains the front direction of the robot, that is, parallel to the Y axis, no matter how the first and second horizontal arms 3 and 4 turn and bend. Link mechanisms 7 and 8 are attached to the arms 3 and 4. Further, the second horizontal arm 4 and the front-facing arm 5 are arranged below the first horizontal arm 3.

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 tip of the multi-joint operating arm section 6. This gripping tool 1
1 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 that 10 is a weight balance spring.

Regarding the X-axis (lateral direction) and Y-axis (front-back direction) as the robot's three-axis movement of the X, Y, and Z axes, the respective base points O ₁ and O ₂ of the first and second horizontal arms 3 and 4 are This is performed by a horizontal rotation operation using the fulcrum and a horizontal rotation operation using the base point _O4 of the gripping tool 11 as a fulcrum. Regarding the Z axis (vertical direction), the vertical rotation movement is performed by the vertical movement of the vertical cylinder 9 that suspends the gripping tool 11. It is carried out with Since the stroke range for this displacement in the Z-axis direction is not large during assembly work, an ordinary cylinder is sufficient, but if necessary, the first horizontal arm 3 may be attached to the turning disc 2 during initial rough positioning and during assembly work. It is possible to carry out a wider range of movement in the Z-axis direction by incorporating a lifting device that moves up and down.

Next, the assembly work performed 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 horizontal 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 gripper 11 is moved to the second position.
It may also be attached to the tip of the horizontal arm 4.

The assembly robot of this embodiment is strong against external force when force is applied in the Z-axis direction, so
The tip of the gripper 11 has a selective softness that hardly causes any displacement, but it moves softly when an external force is applied in the X-axis direction or the Y-axis direction, so even a relatively small force can cause displacement in the lateral direction. do. Therefore, for example, when inserting a part into a hole, even if the position of the part does not match the hole accurately and misalignment occurs, if the part hits the chamfer of the hole and receives external force, the multi-joint actuating arm The part 6 is displaced only in the horizontal direction by the horizontal component of the external force, so that the part and the hole are aligned, so that the part can be inserted into the hole accurately and quickly. The same applies to moments, and as a result, the work is less complicated when inserting parts into holes, press-fitting, etc., so there is no damage to parts or holes, and the efficiency of assembly work is greatly improved. Can be done.

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 , the length of the front-facing arm 5 is R ₃ ,
When the length of the gripper 11 is R ₄ , the distance of each arm and gripper in the X-axis direction is
Let A ₁ , A ₂ , A ₄ be the distance in the Y-axis direction (since the front facing arm 5 is parallel to the Y-axis, the distance in the X-axis direction is 0), and let the distance in the Y-axis direction be B ₁ , B ₂ , B ₃ , B ₄ Then, A ₄ , B ₃ , B ₄ out of these X and Y axis direction distances are
Since it is based on the rotation angle γ of 1 and the front-facing arm 5, it is only necessary to calculate the displacements A ₁ , A ₂ , B ₁ , and B ₂ , and the base point of the robot can be calculated using a simple calculation formula.
Distance x in the X-axis direction from O ₁ to the tip of the gripper 11
and the distance y in the Y-axis direction can be calculated using the following equations.

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 from 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 ), ... (x _{o ,} yo , z _o ). Thermal distortion and assembly errors can be reduced by installing sensors as necessary (α),
(β) This is done by correcting 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 trajectory of a predetermined object using a teaching roller type.

Master slap type 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.
This is done by determining the starting point of the Y-axis and teaching on the drawing, and on the other hand, making the robot body 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 part of the gripping device is formed of a multi-joint actuating arm part that has directional softness against external forces applied to the gripping device, and Since it is configured with a vertical axis, it has a simple configuration, and assembly work can be passively and quickly corrected without any complications. In addition, it has a multi-joint operating arm that can rotate horizontally and has other arms located below the arm attached to the support, so it has a smaller work area compared to conventional orthogonal coordinate robots. can be made wider. Furthermore, the robot control and associated configuration are simplified,
It has excellent effects such as enabling teaching using a numerical control method, improving calculation speed, and helping to reduce storage capacity.

[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, 9...Vertical cylinder, 11
...Gripper, 12...Horizontal turning motor, 13...
Torsional turning motor.

Claims (1)

[Claims] 1 A multi-joint operation consisting of a support body and a plurality of arms sequentially attached to the support body so as to be able to rotate in the horizontal direction, and other arms arranged so as to be located below the arm attached to the support body. an arm section, a vertical shaft attached to the tip of the multi-joint operating arm section, 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 axis. and is configured such that the horizontal flexibility of the multi-joint actuating arm portion and the vertical axis is greater than the vertical flexibility with respect to an external force applied to the gripping device. Robot.