KR102291422B1 - Robotic arm - Google Patents

Abstract

The present invention relates to a robot arm, and more particularly, to a robot arm capable of bending and unfolding fingers of a robot arm with two wires wound in opposite directions on a single pulley.
According to an embodiment of the present invention, there is provided a robot arm having a plurality of fingers and a plurality of knurls for each finger formed so that bending and spreading of the fingers are possible, the robot arm being connected to the fingers and supporting the fingers; a motor connected to each of the fingers and driving the joint to bend or unfold; a pulley connected between the motor and the finger, the pulley including a first spool on which a first wire is wound and a second spool on which a second wire is wound in a direction opposite to the first wire; a control unit for individually controlling the motor; The first wire is coupled to each node along the outer surface of the finger, the second wire is configured to be coupled to each node along the inner surface of the finger, and a motor connected to the finger is driven to rotate the pulley forward. When the first wire and the second wire are respectively wound and unwound, when the pulley rotates in reverse, the first wire and the second wire are respectively unwound and wound, the node is bent or unfolded according to the rotational direction of the motor, the robot provide an arm

Description

Robotic arm

The present invention relates to a robot arm, and more particularly, to a robot arm capable of bending and unfolding fingers of a robot arm with two wires wound in opposite directions on a single pulley.

The demand for robot arms is increasing rapidly in the prosthetic industry, industries that require precise work, or the pollutant processing industry where it is difficult for humans to work directly. have.

In addition, various technologies are being developed in order to implement a movement similar to a human hand movement through a robot arm.

However, in order to precisely control the movement of the robot arm and make it move similarly to a human hand, an individual motor must be provided for each joint. As the number of parts (complexity) increases, not only the risk of failure is high, but also the power consumption increases, so "low power and light weight" and "improving the precision/similarity of the robot arm" are contradictory technologies that are difficult to be compatible with each other. understood as a characteristic.

The robot arm is currently being developed in various forms and types, and among them, a universal robot arm is a "wire-driven hand robot finger device" disclosed in Korean Patent Application Laid-Open No. 10-2011-0001125.

In the above patent document, "a finger device of a hand robot for realizing human hand motion, a first joint having a free end and an end coupled to the first link, a first joint composed of both side plates, a first link of the first joint, and A second joint portion configured to operate integrally with both side plates extending between opposing second links, and both side plates extending between a third link positioned opposite to the second link of the second joint portion to operate integrally A third joint portion made of, and a drive motor for respectively stretching and contracting the second joint portion and the third joint portion, wherein the link of the first joint portion and the link of the second joint portion are connected by a restraining means to operate in association with each other, A wire for operating a second joint is mounted between the link of the second joint and the rotation shaft of the second drive motor, and a wire for operating the third joint is mounted between the link of the third joint and the rotation shaft of the first drive motor. A wire-driven hand robot finger device with

In the prior art as described above, a motor is individually connected to each knuckle in order to implement a knuckle motion (refer to FIG. 4, reference numerals 50a/50b), and due to this configuration, an increase in weight, an increase in power consumption, and a failure are prevented. Since problems such as increased risk occur, there is a great need for improvement.

The problem to be solved by the present invention is to provide a lightweight and structurally simplified robot arm that can implement the joint folding/unfolding motion of a finger with a single motor in order to solve the problems of the conventional robot arm technology as described above. .

In order to solve the problems of the conventional robot arm, a plurality of fingers (1) and a plurality of joints (11) for each finger (1) are formed, so that bending and unfolding of the finger (1) is possible. In the palm (2) connected to the finger (1) for supporting the finger (1); a motor connected to each of the fingers (1) and driving the knuckle (11) to bend or unfold; It is connected between the motor and the finger 1, and the first spool 31 on which the first wire 311 is wound, and the second wire 321 on which the second wire 321 is wound in the opposite direction to the first wire 311. a pulley 3 comprising a spool 32 and; a control unit for individually controlling the motor; The first wire 311 is coupled to each joint 11 along the outer surface of the finger 1 , and the second wire 321 is coupled to each joint 11 along the inner surface of the finger 1 . It is configured to be coupled, and the first wire 311 and the second wire 321 are respectively wound and unwound when the pulley 3 is rotated forward by driving the motor connected to the finger 1, and the pulley 3 is When rotating in reverse, the first wire 311 and the second wire 321 are respectively unwound and wound, and the node 11 is bent or unfolded according to the rotation direction of the motor, providing a robot arm.

In addition, the nodes 11 are hinged to each other, and in the nodes 11, the finger 1 is bent only in the direction of the inner surface of the finger 1 in a state in which the finger 1 is spread in a straight line. The locking part 110 to prevent rotation is formed, so that the finger 1 is unfolded when the motor rotates forward, and the finger 1 is spread out in a straight line with the pulley 3 rotated to the maximum forward rotation. It may be configured so that the finger 1 is bent when the motor rotates in reverse.

And, the finger 1 is provided with a flex sensor, and by measuring the current bending state of the finger 1 in real time, the control unit may be configured to adjust the rotation direction and rotation angle of the motor.

In addition, it further comprises a support (4) connected to the palm (2) for supporting the palm (2); The support part 4 has a predetermined space formed therein to accommodate the controller, the motor, the pulley 3 and the battery, and is a folded portion formed between the finger 1, the palm 2 and the support part 4 . And an auxiliary pulley (3) is provided at the connection portion, and the first wire (311) and the second wire (321) extending from the finger (1) through the palm (2) to the pulley (3) are the pulleys (3) When it is wound or unwound in, it may be configured to prevent the jamming of the first wire 311 and the second wire 321 in the folded portion and the connecting portion.

In addition, the radius ratio of the first spool 31 and the second spool 32 is formed in a ratio between 0.84 and 0.88, so that the winding or unwinding length of the first wire 311 is greater than the unwinding length of the second wire 321. Or it may be configured to have a longer winding length.

According to an embodiment of the present invention, it is possible to implement a folding and unfolding operation between a plurality of joints provided in the finger with a single motor.

In addition, by minimizing the number of motors required to implement the robot arm, it is possible to significantly reduce the overall weight of the robot arm.

In addition, the control load (load) of the motor is small and the coupling relationship between detailed parts is simplified compared to the existing technology, so the frequency of failure is remarkably low.

In addition, since the folding and unfolding between the nodes are simultaneously performed according to the movement of the first wire and the second wire, a robot arm with high similarity to a human hand can be implemented.

In addition, by reducing the number of unnecessary electrical components, it is possible to minimize the power consumed for driving the robot arm.

1 is a perspective view of a robot arm according to an embodiment of the present invention.
2 is a side view of a finger of a robot arm according to an embodiment of the present invention.
Figure 3 is a view showing in detail the pulley of the robot arm according to an embodiment of the present invention.
4 is a view showing the radius ratio of the first failure and the second failure provided in the pulley of the robot arm according to an embodiment of the present invention.
5 is a side view of a robot arm according to an embodiment of the present invention.

Hereinafter, various embodiments of the present document will be described with reference to the accompanying drawings. However, this is not intended to limit the technology described in this document to specific embodiments, and it should be understood to include various modifications, equivalents, and/or alternatives of the embodiments of this document. . In connection with the description of the drawings, like reference numerals may be used for like components.

In this document, expressions such as "has," "may have," "includes," or "may include" refer to the presence of a corresponding characteristic (eg, a numerical value, function, operation, or component such as a part). and does not exclude the presence of additional features.

Various modifications can be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims of the present invention, and these modifications are the technical spirit of the present invention or It should not be understood individually from the perspective.

According to an embodiment of the present invention, there is provided a robot arm in which a plurality of fingers and a plurality of joints are formed for each finger so that bending and spreading of the fingers are possible, the robot arm being connected to the fingers and supporting the fingers; a motor connected to each of the fingers and driving the joint to bend or unfold; a pulley connected between the motor and the finger, the pulley including a first spool on which a first wire is wound and a second spool on which a second wire is wound in a direction opposite to the first wire; a control unit for individually controlling the motor; The first wire is coupled to each node along the outer surface of the finger, the second wire is configured to be coupled to each node along the inner surface of the finger, and a motor connected to the finger is driven to cause the pulley to rotate forward. When the first wire and the second wire are wound and unwound, respectively, when the pulley rotates in reverse, the first wire and the second wire are respectively unwound and wound, the node is bent or unfolded according to the rotational direction of the motor, the robot provide an arm

Regardless of the specification or control method of the motor, when one rotational direction of the motor is referred to as forward rotation, rotation in the opposite direction may be defined as reverse rotation. Even if a motor of the same specification is used, the forward and reverse rotation directions may be different depending on the connection direction or location of the motor and the pulley. For example, when the motor is connected to the left side of the pulley, the clockwise rotation of the motor is forward and counterclockwise rotation is reversed, but when the motor is connected to the right side of the pulley, the clockwise rotation of the motor is reversed A clockwise rotation can be a forward rotation. Regardless of the name of forward rotation or reverse rotation, if the first wire and the second wire are respectively wound/unwound or unwound/wound according to the rotation of the pulley, and the finger is spread/bent, it can be said that the configuration is included in the description. can

1 shows an embodiment in which five fingers are provided like a human hand. In an embodiment, five motors may be used to operate each finger individually.

In the conventional robotic arm technology, at least 14 motors and wires had to be combined for each joint in order to operate the two joints of the thumb and the three joints of the remaining four fingers, thereby increasing the weight and increasing the complexity of the device. There was a problem that the frequency was high and the mass productivity was low.

On the other hand, in the embodiment of the present invention, since only 5 motors and a pair of wires for each finger are sufficient, it is possible to reduce the weight of about 64% (9 motors from 14 motors). Except for additional functions (sensors, etc.) not disclosed in the description of the present invention, since the weight of the robot arm is all the weight of the frame and the weight of the motor, the effect of weight reduction by reducing the number of motors as described above is very large. .

3 shows a specific shape of a pulley according to an embodiment of the present invention. Figure 3 (a) shows the pulley in a perspective view so that the first failure (distaff; a tool to wind the thread) and the second failure appear.

Figure 3 (b) shows a side view of the pulley, showing a state in which the first wire and the second wire wound on the first spool and the second spool are unwound and wound. Here, c is the rotational direction (reverse rotation) of the pulley, a is the direction in which the first wire is unwound according to the rotation of the pulley, and b is the direction in which the second wire is wound according to the rotation of the pulley. In order to clearly reveal the structure, the difference in radius between the first failure and the second failure is somewhat exaggerated.

Referring to FIG. 2 , in a situation in which the pulley is reversely rotated as in FIG. 3 ( b ), the first wire is unwound and the second wire is wound, so that the fingers (each joint) are gradually changed into a gripping shape. On the other hand, when the pulley rotates (forward rotation) in the opposite direction to c of FIG. 3 (b), the first wire is wound and the second wire is unwound, so that the finger is gradually changed into an unfolded form.

A wire line is formed in the palm, and the path of the wire can be configured to connect the first wire and/or the second wire extending from each finger to the support part through the palm. This serves to separate the wires coupled to different fingers so that they can move independently of each other without interfering with each other. The wire line is formed to protrude in the direction of the upper surface of the palm as shown in FIG. 1, and the wire line may be composed of four to form a path of the first wire and/or the second wire extending from the finger. .

In addition, the nodes are hinged to each other, and a locking part is formed in the node to prevent rotation of the finger in the direction of the outer surface of the finger so that the finger is bent only in the direction of the inner surface of the finger in a state in which the finger is spread in a straight line. The fingers are spread out when rotating, and the fingers are spread out in a straight line in a state in which the pulley is rotated in the maximum forward direction, and the fingers are bent when the motor rotates in the reverse direction.

Through the configuration of the locking part as described above, the forward rotation limit of the pulley is determined. When the pulley (or motor) is rotated to its forward rotation limit, the fingers may be configured to fully unfold in a straight line.

On the other hand, when the pulley rotates to the reverse rotation limit, it may be configured such that the finger is in a state in which it is maximally rolled. Referring to FIG. 2 , it can be seen that at the forward rotation limit, the knob part is blocked from rotating in the opposite direction by the engaging part, and at the reverse rotation limit, the knob part is blocked so that the knob part is no longer bent in the inner direction of the palm by the body part. .

And, the finger is provided with a flex sensor, by measuring the current bending state of the finger in real time, it may be configured to adjust the rotation direction and rotation angle of the motor in the control unit.

When it is confirmed that the finger is bent in a desired shape, the controller may stop driving a motor corresponding to the finger. If the finger does not reach the desired shape, the motor can be rotated forward or reverse in a direction to reduce the difference in value by comparing the value detected by the flex sensor with the desired state (bending amount) of the finger.

In addition, further comprising a support portion connected to the palm to support the palm; The support part has a predetermined space therein to accommodate the controller, the motor, the pulley and the battery, and an auxiliary pulley is provided at the folding part and the connecting part formed between the finger, the palm and the support part, When the first wire and the second wire extending through the pulley are wound or unwound from the pulley, it may be configured to prevent the first wire and the second wire from jamming in the folded portion and the connecting portion.

The folded portion may mean a portion in which each node is folded (bent) and a portion in which a finger-palm is bent. In addition, although the connection portion is not folded, it may mean a portion in which each member constituting a path through which the first wire or the second wire passes is connected. A portion of the folded portion and the connecting portion is shown in FIG. 5 . The connection part may be between the palm and the thumb coupling part, between the thumb coupling part and the first joint of the thumb, and between the palm and the support part.

The auxiliary pulley may not be a member in which the first wire or the second wire is wound, unlike the pulley provided with the first and second failures. By inserting the first wire or the second wire into the groove of the auxiliary pulley, it is possible to prevent separation of the first wire and the second wire and abrasion due to friction with the folded portion or the connecting portion.

In addition, the radius ratio of the first failure and the second failure is formed in a ratio between 0.84 and 0.88, so that the unwinding or winding length of the second wire is longer than the winding or unwinding length of the first wire.

4 is a view showing the ratio (r1/r2) of the radius r1 of the first failure to the radius r2 of the second failure with the angle between the nodes being the x-axis. The angle θ (theta) between the joints is defined as 0 (0 radians = 0 degrees) when the fingers are spread out in a straight line, and ∏/2 (radians, 90 degrees) when the two joints are perpendicular to each other, and the rotation of the pulley If the change in length of the first wire and the second wire according to (change in the length of the wire in the unwound state) according to

, (r은 힌지 중심으로부터 힌지 외주면까지의 거리; 도 2에 도시됨)The amount of change in length of the first wire is

, (r is the distance from the center of the hinge to the outer circumferential surface of the hinge; shown in Fig. 2)

가 되며,The amount of change in length of the second wire is

becomes,

)와 도르래의 회전각도(

)의 곱

, 제1실패의 권취/권출길이(

)와 도르래의 회전각도(

)의 곱

으로 나타낼 수 있다.This is the winding/unwinding length (

) and the rotation angle of the pulley (

) product

, the winding/unwinding length of the first failure (

) and the rotation angle of the pulley (

) product

can be expressed as

thus,

및

and

가 성립하고,

is established,

Dividing the two expressions, we get

가 성립한다.

is established

It can be confirmed that the ratio of the radius of the first failure to the radius of the second failure is a function of the angle, and the ratio of the radius of the first failure to the radius of the second failure according to the angle (unit: degrees, range: 1-90) A diagram showing the is shown in FIG. 4 .

In the above formula, the maximum value is 0.995668, the minimum value is 0.786376, and the average is 0.867717, and it can be confirmed that the average peripheral value of 0.84 to 0.88 is a preferable ratio in order to maintain proper wire elasticity in all ranges.

1: finger 110: locking part
11: node 111: body part
2: palm a: first wire unwinding direction
20: wire line b: second wire winding direction
21: thumb coupling part c: pulley rotation direction
3: Pulley X: Folded part
31: first failure Y: connection part
311: first wire
32: second failure
321: second wire
4: support

Claims (5)

In a robot arm, in which a plurality of fingers and a plurality of joints for each finger are formed so that bending and unfolding of the fingers is possible,
a palm connected to the finger to support the finger; a motor connected to each of the fingers and driving the joint to bend or unfold; a pulley connected between the motor and the finger, the pulley including a first spool on which a first wire is wound and a second spool on which a second wire is wound in a direction opposite to the first wire; a control unit for individually controlling the motor; and a support part connected to the palm to support the palm,
Four wire lines are formed to protrude in the direction of the upper surface of the palm, and the wire lines constitute a path of the wire so that the first wire extending from each finger is connected to the support part,
The first wire is coupled to each node along the outer surface of the finger, the second wire is configured to be coupled to each node along the inner surface of the finger, and a motor connected to the finger is driven to rotate the pulley forward. When the first wire and the second wire are respectively wound and unwound, when the pulley is reversely rotated, the first wire and the second wire are respectively unwound and wound, the node is bent or unfolded according to the rotational direction of the motor,
The nodes are hinged to each other, and a locking part is formed in the nodes to prevent rotation of the finger in the direction of the outer surface of the finger so that the finger is bent only in the direction of the inner surface of the finger in a state in which the finger is unfolded in a straight line, when the motor rotates forward The fingers are spread out, and the fingers are spread out in a straight line in a state in which the pulley is rotated in the maximum forward direction, and the fingers are bent when the motor rotates in the reverse direction,
The finger is provided with a flex sensor, and by measuring the current bending state of the finger in real time, the control unit is configured to adjust the rotation direction and rotation angle of the motor,
The support part has a predetermined space therein to accommodate a control unit, a motor, a pulley, and a battery, and an auxiliary pulley is provided in the folded portion and the connecting portion formed between the finger, palm, and the support portion, from the finger through the palm. When the first wire and the second wire extending to the pulley are wound or unwound from the pulley, it is configured to prevent the jamming of the first wire and the second wire at the folded portion and the connecting portion,
The radius ratio of the first failure and the second failure is formed in a ratio between 0.84 and 0.88, so that the unwinding or unwinding length of the second wire is longer than the winding or unwinding length of the first wire, the robot arm delete delete delete delete

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