KR102448594B1 - Joint apparatus and robot comprising the same - Google Patents

Abstract

A joint apparatus according to the present embodiment comprises a first plate, a second plate, a ball joint unit, a universal joint unit, and a revolute joint unit, and comprises a plurality of links located between the first plate and the second plate and a plurality of stoppers preventing the links from yielding, wherein the plurality of links provide compliance to the joint apparatus. The joint apparatus allows assembly without damaging a robot.

Description

JOINT APPARATUS AND ROBOT COMPRISING THE SAME

The present technology relates to a joint device and a robot comprising the same.

Articles manufactured in the manufacturing industry are manufactured by assembling various types of parts, and are assembled and manufactured using automated equipment such as robots, not manual work, in order to obtain high productivity. Furthermore, with the recent advancement of robot control technology, robots are replacing manpower in many production processes. However, the assembly process can fail even with very small errors, which can cause serious damage between the assembly parts and the robot performing the assembly, making automation difficult.

Currently, the technology used in the peg-in-hole operation, which is the simplest assembly process, uses an external sensor that can measure the assembly status, such as a force/torque sensor, a vision sensor, or RCC (Remote Center Compliance). It uses the same passive compliance device.

In the prior art, a sensor is mounted on a joint of a robot to measure a contact force generated between assemblies, and the robot estimates the position and posture of a contact point and a hole to be assembled through this. The amount of misalignment can be calculated through the estimated value and the assembly can be completed while maintaining the contact force between the parts below a certain amount using feedback.

To control the robot's motion, it is necessary to measure the linear displacement, rotation angle, and force/torque of the robot's joints. A torque sensor is used to measure the torque acting on the robot joints. However, the torque sensor is expensive, and the structure becomes very complicated in order to mount the torque sensor.

One of the challenges to be solved by this technology is to provide a sensor capable of measuring the physical properties of a joint when assembling with a robot, a product to be assembled, and a joint device capable of performing assembly without damaging the robot.

The joint device according to this embodiment includes: a first plate, a second plate, a ball joint unit, a universal joint unit, and a revolute joint unit; A plurality of links (links) positioned between the first plate and the second plate and a plurality of stoppers (stoppers) for preventing the yielding of the links, the plurality of links provides compliance (compliance) to the articulation device.

The robot according to this embodiment includes: a robot arm; a gripper and a joint connected between the robot arm and the gripper, the joint comprising: a first plate, a second plate, a ball joint unit, a universal joint unit, and a revolute a joint unit), and a plurality of links positioned between the first plate and the second plate and a plurality of stoppers for preventing the yielding of the link, the plurality of links being compliant to the joint device (compliance) is provided.

According to the articulation device of this embodiment, it has six degrees of freedom, and has the advantage of having a larger range of displacement with low stress compared to the prior art.

1 is a perspective view showing the outline of the joint device according to the present embodiment.
Fig. 2(a) is a perspective view showing the outline of the link, and Fig. 2(b) is a side view showing the operation of the link.
Figure 3 (a) is a plan view of the joint device, Figure 3 (b) is a bottom view of the joint device.
4 is a diagram schematically illustrating a robot using the joint device according to the present embodiment.
5 is a view showing the results of simulation of the maximum displacement and yield stress of the joint device according to the present embodiment.

Hereinafter, this embodiment will be described with reference to the accompanying drawings. 1 is a perspective view showing the outline of the joint device 10 according to the present embodiment. 1, the joint device 10 according to this embodiment is a first plate 110, a second plate 120, a ball joint unit (ball joint unit), a universal joint unit (universal joint unit) and a revolute joint unit, a plurality of links 210 positioned between the first plate and the second plate, and a plurality of stoppers 300 for preventing the yielding of the links. Including, a plurality of links provide compliance (compliance) to the articulation device.

In one embodiment, the links 210 may be formed of a flexible material such as nylon 6. The joint device 10 includes a displacement in the x-axis direction (Δx), a displacement in the y-axis direction (Δy), a displacement in the z-axis direction (Δz), a rotational displacement about the x-axis (Δθx), and a rotation about the y-axis It has six degrees of freedom: displacement (Δθy), rotational displacement (Δθz) about the z axis.

The first connection part 218a (refer to FIG. 2 ) and the second connection part 218b (refer to FIG. 2 ) of the link 210 may be inserted and fixed to the first plate 110 and the second plate 120, respectively. In addition, one end of the stopper 300 may be fixed to any one of the first plate 110 and the second plate 120 , and the stopper ( 300) may be inserted so that the other end is playable (see FIG. 3). In an embodiment, the first plate 110 and the second plate 120 may be formed of a rigid material such as aluminum or stainless steel.

The articulation device 10 includes a stopper 300 . In the illustrated embodiment, one end of the stopper 300 is fixed to the first plate 110 , and the other end is movably inserted into the hole 120h (see FIG. 3B ) formed in the second plate 120 ). .

2 (a) is a perspective view showing the outline of the link (210), Figure 2 (b) is a side view of the link (210) showing the operation of the link (210). 1, 2 (a) and 2 (b), the link 210 is a revolute joint unit (revolute joint unit, 212), a universal joint unit (universal joint unit, 214) and a ball joint unit (ball) joint unit, 216).

In one embodiment, the link 210 includes a first connection part 218a inserted into the first plate 110 (see FIG. 1) and a second connection part 218b inserted into the second plate 120 (see FIG. 1). may include more.

The rotary joint part 212 includes a bending surface (Rs1) as illustrated in FIGS. 2(a) and 2(b), and functions as a rotary joint by bending the bending surface (Rs1). Bending in the rotary joint part 214 included in the link 210 disposed between the first plate 110 and the second plate 120 as in the embodiment illustrated in FIGS. 2 ( a ) and 2 ( b ). The surface Rs1 may be in a rotated state by being offset by a predetermined angle in advance. For example, when the link 210 is disposed between the first plate 110 and the second plate 120 in a straight line without an offset, the pressure between the first plate 110 and the second plate 120 is When applied, it is not determined whether the rotational direction of the rotary joint is clockwise or counterclockwise, so a singularity may be formed. Accordingly, it is possible to prevent the formation of a singular point by pre-offset rotation of the rotary joint unit 212 .

The universal joint part 214 includes a second bending surface Rs2 and a third bending surface Rs3 that can be bent in different directions, respectively, as illustrated. The second bending surface Rs2 and the third bending surface Rs3 are bent so that the link 210 can rotate in two different directions. The ball joint part 216 allows the link 210 to rotate about the longitudinal axis of the link 210 .

1, 2(a) and 2(b), the link 210 is a ball joint portion 216, a universal joint portion 214 and a rotary joint portion 212 in the second plate. Although connected to the first plate in order, this is merely an example, and the order in which each joint part is arranged in the link may be modified.

In the illustrated embodiment, the strain sensor 400 for measuring the strain provided to the link is located on the bending surface Rs1 of the rotary joint part 212 . As will be described later, it is possible to obtain the displacement, rotation angle displacement, force and moment of the joint device 10 using the values measured by the strain sensor.

FIG. 2( a ) illustrates that the strain sensor 400 is positioned on the bending surface Rs1 of the rotary joint part 212 . However, in an embodiment not shown, the strain sensor 400 is the second bending surface Rs2, the third bending surface Rs3, or the rotary joint portion 216 of the universal joint portion 214 of the link 210 . located in at least one of

Figure 3 (a) is a plan view of the joint device (10), Figure 3 (b) is a bottom view of the joint device (10). 1 to 3 ( a ) and 3 ( b ), the first connecting portions 218a of the links 210 are inserted and connected to the first plate 110 . In addition, one end 300a of the stopper 300 is fixed to the first plate 110 . The second connecting portions 218b of the links 210 are inserted and connected to the second plate 120 . In addition, holes 120h into which the other ends of the stopper 300 are spaced apart are formed in the second plate 120 .

However, this is merely an embodiment, and one end of the stopper 300 is fixed to the second plate 120 , and the other end may be movably inserted into the hole formed in the first plate 110 . The stopper 300 may be formed of a rigid material such as stainless steel or aluminum.

A strain is applied to the link 210 connecting the first plate 110 and the second plate 120 as the first plate 110 and the second plate 120 move during the operation of the joint device 10 . . One end 300a of the stopper 300 is fixed to the first plate 110 and moves together with the first plate 110 , but the other end of the stopper 300 has a hole 120h formed in the second plate 120 . ) can be moved within the link 210 can be prevented from being provided with a stress greater than the yield stress.

As illustrated in FIGS. 3( a ) and 3 ( b ), the links 210 may be arranged in pairs, and the pair of links 210 is the first plate 110 , the second plate 120 . They may be spaced apart from each other at the same angle from the center. The illustrated embodiment illustrates that three pairs of links 210 are formed, and the pairs of links 21 are spaced apart from each other by 120 degrees with respect to the center of the first plate 110 and the second plate 120 from each other. . However, this is merely an example, and a pair of four links 210 may be disposed to be spaced apart from each other by 90 degrees with respect to the center of the first plate 110 and the second plate 120 . Similarly to the not-shown embodiment, four or more link pairs may be disposed.

A strain sensor 400 is disposed in the joint device 10 having the above configuration to measure the strain provided during the operation of the joint device 10 . In the embodiment illustrated by FIGS. 1 to 3 ( a ) and 3 ( b ), the strain sensor 400 is located on each of the six links 210 . When force and torque are applied to each axis, the strain measured by the strain sensor 400 is a small strain, so it can be assumed to be linear. can

Displacement, force, and moment can be obtained as in Equation 1 below from the measured values from the strain sensor 400 located in each link 210 .

[Equation 1]

Referring to Equation ① of Equation 1, when an operation is performed with a predefined coefficient matrix (A) and a measurement value matrix (S) of the strain sensor 400 located in each link 210, displacement in the x-axis direction (Δx), displacement in the y-axis direction (Δy), displacement in the z-axis direction (Δz), rotational displacement about the x-axis (Δθx), rotational displacement about the y-axis (Δθy), rotation about the z-axis The displacement (Δθz) can be obtained.

Furthermore, referring to the ② expression of Equation 1, when the operation is performed with the predefined coefficient matrix (B) and the measured value matrix (S) of the strain sensor 400 located in each link 210, the joint device ( 10) the x component of the force (F _x ), the y component of the force (F _y ), the z component of the force (F _z ), the x component of the moment (M _x ), the y component of the moment (M _y ), The z component of the moment (M _z ) can be obtained. Therefore, according to the joint device 10 according to the present embodiment, it can operate as a sensor capable of measuring displacement, force and moment.

According to the joint device 10 according to the present embodiment, it is possible to measure the reaction force generated during the assembly process, to provide manual compliance, and to measure the displacement caused by the manual compliance, so that the joint can flexibly cope in various assembly processes. A device is provided.

4 is a diagram schematically illustrating a robot using the joint device 10 according to the present embodiment. Referring to FIG. 4 , the robot 1 is controlled by the controller and driven by the actuator, the robot arm 1000 and the gripper 3000 for holding the assembly target object, and the joint device 10 according to the present embodiment. may include

Since the robot illustrated in FIG. 4 has 6 degrees of freedom by the joint device 10, it is capable of sensing force and torque that the prior art cannot provide and has passive compliance. Therefore, if the misalignment of the items to be assembled is within a range that can be corrected, the assembly process can be quickly completed. If the misalignment is within a range that cannot be corrected, the assembly process can be performed through feedback control using a force/torque sensor. .

In the work using the force / torque sensor of the prior art, it is necessary to control it slowly until the assembly is completed. You can get the job done quickly.

imitation Experimental example

5 is a view showing the results of simulation of the maximum displacement and yield stress of the joint device according to the present embodiment. Nylon 6 was assumed as the material for forming the link, and a simulation was performed with the stopper removed to find the maximum displacement and yield stress.

Referring to FIG. 5 , when a displacement of 2 mm was applied between the first plate and the second plate, a maximum stress of 64 MPa occurred, which is lower than the yield stress of nylon 6 of 87 MPa. In addition, as a result of performing the analysis by the finite element method (FEM), it was possible to generate a displacement of 2 mm in the horizontal direction. It can be confirmed that, in spite of a large displacement, low stress is generated compared to the maximum stress of 251 MPa when a displacement of 0.4 mm is applied in the prior art.

Although it has been described with reference to the embodiment shown in the drawings in order to help the understanding of the present invention, this is an embodiment for implementation, it is merely an example, and various modifications and equivalents from those of ordinary skill in the art It will be appreciated that other embodiments are possible. Accordingly, the true technical protection scope of the present invention should be defined by the appended claims.

10: articulation device 110: first plate
120: second plate 210: link
212: rotary joint part 214: universal joint part
216: ball joint 218a: first connection part
218b: second connection part 300: stopper
400: strain sensor 1000: robot arm
3000: gripper Rs1, Rs2, Rs3: bending face

Claims (27)

An articulation device, the articulation device comprising:
a first plate;
second plate
A plurality of links comprising a ball joint unit, a universal joint unit and a revolute joint unit, the links positioned between the first plate and the second plate. and
It includes a plurality of stoppers (stoppers) to prevent the yield of the link,
The plurality of links is an articulation device for providing compliance (compliance) to the articulation device. According to claim 1,
Each of the above links is
The ball joint part, the universal joint part, and the joint device formed integrally with the rotary joint part in a straight line form. According to claim 1,
Each of the above links is
The ball joint part, the universal joint part, and the rotary joint part are integrally formed in order to form a straight joint device. 3. The method of claim 2,
Each of the above links is
Any one of the ball joint part and the rotary joint is connected to the first plate,
The other of the ball joint portion and the rotary joint is a joint device connected to the second plate. 3. The method of claim 2,
Each of the above links is
placed in pairs,
The pair of links is a joint device arranged at an equal angle to each other based on the center of the first plate and the second plate. 3. The method of claim 2,
Each of the above links is
It is made of flexible material,
An articulation device that provides 6 Degrees of Freedom to the articulation device. According to claim 1,
The joint device is
The joint device is arranged to be rotated offset by a certain angle of the rotary joint. According to claim 1,
Each of the plurality of stoppers,
A joint device formed of a rigid material. 9. The method of claim 8,
Each of the plurality of stoppers,
It is fixedly connected to any one of the first plate and the second plate,
A joint device positioned so that any other of the first plate and the second plate can move within a predetermined clearance distance. According to claim 1,
The plurality of stoppers
An articulating device comprising three stoppers arranged conformally to each other. According to claim 1,
The joint device is
The joint device further comprising a strain sensor positioned on each of the links to measure the strain of the link. 12. The method of claim 11,
The joint device is
The displacement in the x-axis direction (Δx), the displacement in the y-axis direction (Δy), the displacement in the z-axis direction (Δz), and the rotational displacement ( Δθx), rotational displacement about y-axis (Δθy), rotational displacement about z-axis (Δθz), x-component of force (F _x ), y-component of force (F _y ), z-component of force (F _z ) ), the x component of the moment (M _x ), the y component of the moment (M _y ), and the z component of the moment (M _z ) A joint device that functions as a sensor that can measure any one or more. As a robot, a robot is:
robotic arm;
gripper and
a joint connected between the robot arm and the gripper;
The joint is:
a first plate and a second plate;
A plurality of links comprising a ball joint unit, a universal joint unit and a revolute joint unit, the links positioned between the first plate and the second plate. and
It includes a plurality of stoppers (stoppers) to prevent the yield of the link,
The plurality of links is a robot that provides compliance (compliance) to the articulation device. 14. The method of claim 13,
Each of the above links is
The ball joint part, the universal joint part, and the rotary joint part are integrally formed to form a straight line. 14. The method of claim 13,
Each of the above links is
The ball joint part, the universal joint part, and the rotary joint part are integrally formed in order to form a straight line. 15. The method of claim 14,
Each of the above links is
Any one of the ball joint part and the rotary joint is connected to the first plate,
The other one of the ball joint part and the rotary joint is connected to the second plate. 15. The method of claim 14,
Each of the above links is
placed in pairs,
The pair of links is arranged to be spaced apart from each other at an equal angle with respect to the center of the first plate and the second plate. 15. The method of claim 14,
Each of the above links is
It is made of flexible material,
A robot that provides 6 Degrees of Freedom to the articulation device. 14. The method of claim 13,
The joint device is
A robot in which the rotary joint part is rotated offset by a certain angle. 20. The method of claim 19,
The joint device is
A robot in which the rotary joint is rotated according to the offset. 14. The method of claim 13,
Each of the plurality of stoppers,
A robot made of a rigid material. 22. The method of claim 21,
Each of the plurality of stoppers,
It is fixedly connected to any one of the first plate and the second plate,
The robot is positioned so that any one of the first plate and the second plate can move within a predetermined clearance distance. 14. The method of claim 13,
The plurality of stoppers are
A robot comprising three stoppers arranged isometrically to each other. 14. The method of claim 13,
The joint device is
Further comprising a sensor for measuring an x-axis displacement, a y-axis displacement, a z-axis displacement, an x-axis rotation angle, a y-axis rotation angle, and a z-axis rotation angle with respect to any one of the first plate and the second plate robot that does. 14. The method of claim 13,
any one of the first plate and the second plate is connected to the gripper,
the other of the first plate and the second plate is connected to the robot arm. 14. The method of claim 13,
The joint device is
The robot further comprising a strain sensor positioned on each of the links to measure the strain of the link. 27. The method of claim 26,
The robot is
The displacement in the x-axis direction (Δx), the displacement in the y-axis direction (Δy), the displacement in the z-axis direction (Δz), and the rotational displacement ( Δθx), rotational displacement about y-axis (Δθy), rotational displacement about z-axis (Δθz), x-component of force (F _x ), y-component of force (F _y ), z-component of force (F _z ) ), the x component of the moment (M _x ), the y component of the moment (M _y ), and the z component of the moment (M _z ).

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