KR101839317B1 - End effector capable of being actuated by cable tension and cable-driven parallel robot comprising same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end effector that can be driven by cable tension and a parallel cable robot including the end effector. More particularly, the present invention relates to an end effector capable of simultaneously driving cable tensions in a specific relationship and a cable robot . The end effector 100 according to an embodiment of the present invention includes a body 102; A fixing part 104 installed on the body part 102; A moving part 106 movably formed with respect to the fixed part 104; A cable 40 connected to the moving part 106; A plurality of guide pulleys (116) mounted on the body portion (102) such that the cable (40) passes through at least a portion of the perimeter; A stopper means 118 formed on the body portion 102 to be spaced apart from the moving portion 106; And an elastic member 120 installed between the moving portion 106 and the stopper means 118 to be stretched or compressed.

Description

[0001] The present invention relates to an end effector which can be driven by a cable tension, and a parallel cable robot including the end effector.

The present invention relates to an end effector that can be driven by cable tension and a parallel cable robot including the same. More particularly, the present invention relates to a parallel cable robot in which a plurality of cables are connected in parallel to an end effector instead of a conventional rigid body And an end effector capable of driving the cable tension by changing the cable tension in a specific relationship at the same time.

Unlike conventional serial robots or parallel robots, parallel cable robots are robotic systems that drive end effectors by connecting multiple end effectors and frames in parallel with a number of lightweight and flexible cables, and using a number of winches to wind and unwrap cables. Parallel cable robots are very small in inertia because they are lightweight and most of the actuators are fixed, which is a very effective alternative to work requiring high dynamic characteristics or energy efficiency. In addition, conventional series or parallel type industrial robots limit the work space in which the end effector of the robot can move due to the link length, while parallel type cable robots elaborate the length of the cable from several meters to several hundred meters Since the winch system is used, the work space can be greatly increased and the work space can be easily changed according to the shape of the frame. Recently, efforts to use cable robots in various fields are continuing due to these advantages.

However, cable robots have the disadvantage of overcoming their advantages. Since the cable is utilized for the first time, accuracy can be degraded due to the slack of the cable or the inaccuracy of the position information of the fixed pulley of the cable. Due to the nature of the cable, (I.e., the work space for rotation is small), and more actuators (winches) than the number of degrees of freedom must be used.

That is, two cables and winches are required to realize one-dimensional movement (linear motion) of the end effector, and at least three cables and winches are required to realize two degrees of freedom planar motion (displacement only change) In order to realize the planar motion (two-dimensional displacement and direction), at least four, and finally, to realize 6 degrees-of-freedom motion in space, a minimum of 7 cables and winches are required and usually 8 cases are used .

Using n + 1 or more actuators to drive robots with n degrees of freedom is usually not good and incurs unnecessary costs.

In the present invention, it is proposed to use the added additional degrees of freedom to further drive the end effector.

US Patent Registration Publication No. US 7,753,642 (registered on July 13, 2010)

SUMMARY OF THE INVENTION The present invention has been conceived to solve the problems described above, and it is an object of the present invention to provide an invention capable of simultaneously applying a tension to a cable in a specific relationship to realize additional motion in the end effector, I want to.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned may be clearly understood by those skilled in the art from the following description.

The features of the present invention for achieving the objects of the present invention as described above and performing the characteristic functions of the present invention described below are as follows.

An end effector that can be driven by cable tension according to an embodiment of the present invention includes: a body portion; A fixing part provided on the body part; A moving part movably formed with respect to the fixed part; A cable connected to the moving part; A plurality of guide pulleys provided on the body portion so that the cable passes through at least a portion of the circumference; Stopper means formed on the body portion to be spaced apart from the moving portion; And an elastic member provided between the moving unit and the stopper unit and being stretched or compressed.

A parallel cable robot including an end effector that can be driven by cable tension according to an embodiment of the present invention includes a frame provided with a winch capable of winding cables; And an end effector disposed in the frame, the end effector comprising: a body portion; a fixing portion provided on the body portion; a moving portion movably formed with respect to the fixing portion; and a plurality of guide pulleys wound on the winch, A cable driving end effector including a cable connected to the moving part guided by the moving part, stopper means formed on the body apart from the moving part, and an elastic member provided between the moving part and the stopper device and being stretched or compressed have.

In addition, the parallel cable robot according to an embodiment of the present invention may further include a controller for controlling at least one of a length and a tension of the cable.

According to an aspect of the present invention, the control unit includes an inverse kinematic operation unit for calculating a cable length from a frame to a set target position using an inverse kinematics; An equilibrium tension calculator for calculating a tension of the cable for maintaining the balance of the end effector on the basis of the set target force or torque value; And a compensation length calculator for calculating a cable length required for operation of the end effector.

As described above, according to the present invention, when n + 1 or more cable drivers are used for the development of cable robots having n degrees of freedom movement, it is possible to use a parallel cable robot using additional degrees of freedom It is possible to implement the additional drive necessary for various operations of the end effector which can be utilized and it is unnecessary to use an additional actuator such as a pneumatic motor, a DC motor, and a servo motor for driving the end effector unlike the prior art. The effort required for control can be reduced.

1 shows a front view of an end effector according to an embodiment of the present invention,
Figure 2 shows a perspective view of an end effector according to an embodiment of the invention,
FIG. 3A is a front view of an end effector according to an embodiment of the present invention,
3B is a front view of an end effector according to an embodiment of the present invention,
4A is a perspective view of an end effector according to an embodiment of the present invention,
4B is a perspective view of an end effector according to an embodiment of the present invention,
Figs. 5A and 5B show an example of the gripper shape,
Figure 6 shows a front view of an end effector in accordance with an embodiment of the present invention,
FIG. 7 illustrates a parallel cable robot according to an embodiment of the present invention,
8 shows a control diagram of a parallel cable robot according to an embodiment of the present invention.

The specific structure or functional description presented in the embodiment of the present invention is merely illustrative for the purpose of illustrating an embodiment according to the concept of the present invention, and embodiments according to the concept of the present invention can be implemented in various forms. Also, it should be understood that the present invention should not be construed as limited to the embodiments described herein, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

Meanwhile, in the present invention, the terms first and / or second etc. may be used to describe various components, but the components are not limited to the terms. The terms may be referred to as a second element only for the purpose of distinguishing one element from another, for example, to the extent that it does not depart from the scope of the invention in accordance with the concept of the present invention, Similarly, the second component may also be referred to as the first component.

Whenever an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but it should be understood that other elements may be present in between something to do. On the other hand, when it is mentioned that an element is "directly connected" or "directly contacted" to another element, it should be understood that there are no other elements in between. Other expressions for describing the relationship between components, such as "between" and "between" or "adjacent to" and "directly adjacent to" should also be interpreted.

Like reference numerals designate like elements throughout the specification. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. &Quot; comprises "and / or" comprising ", as used herein, unless the recited element, step, operation, and / Or additions.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, an end effector 100 according to an embodiment of the present invention includes a body 102; A fixing part 104 installed on the body part 102; A moving part 106 movably formed with respect to the fixed part 104; A cable 40 connected to the moving part 106; A plurality of guide pulleys (116) mounted on the body portion (102) such that the cable (40) passes through at least a portion of the perimeter; A stopper means 118 formed on the body portion 102 to be spaced apart from the moving portion 106; And an elastic member 120 installed between the moving portion 106 and the stopper means 118 to be stretched or compressed.

1, the moving part 106 provided on the body part 102 is provided so as to be rotatable on both sides with respect to the fixed part 104, and the moving part 106 is rotated by the cable 40 . The direction of travel of the cable 40 is adjusted by a plurality of guide pulleys 116 provided on the body 102. An elastic member 120 is connected to the stopper means 118 provided on the body 102 and the elastic member 120 is disposed between the moving portion 106 and the stopper means 118 to move the moving portion 106 .

The end effector 100 according to an embodiment of the present invention may employ a gripper portion as shown in FIG. The end effector 100 according to an embodiment of the present invention includes a body 102; A gripper portion 108 including a pair of jaws pivotally connected to the body portion 102 and symmetrical to each other and a moving portion 106 connecting the pair of jaws; A cable 40 connected to the moving part 106 to linearly move the moving part 106; A plurality of guide pulleys (116) mounted on the body portion (102) such that the cable (40) passes through at least a portion of the perimeter; A stopper means 118 formed on the body portion 102 to be spaced apart from the moving portion 106; And an elastic member 120 installed between the moving part 106 and the stopper means 118 and stretching or compressing in parallel with the moving direction of the moving part 106. [

2, the end effector 100 according to an embodiment of the present invention may include a body 102 and a gripper portion 108. [

The gripper portion 108 is connected to the body 102. Preferably, the gripper portion 108 includes a pair of jaws symmetrical to each other, and each jaw may be pivotally connected to the body 102. The pair of jaws can be pivotally connected to the body 102 by means of the fixing part 104. The fixing portion 104 may be a fixing means separate from the body 102 as shown in FIG. 2 and may be directly connected to the body 102 by screws, pins, or the like.

The gripper portion 108 may include a moving portion 106 connecting the pair of jaws. The moving part 106 is installed so as to be linearly movable with respect to the body 102. More specifically, the moving portion 106 can be formed to be linearly movable in a direction parallel to the fixed portion 104 with respect to the body 102. As shown in FIGS. 3A and 3B, the pair of jaws can be closely contacted or moved away from each other by the linear movement of the moving unit 106.

The pair of jaws includes a first connecting member 110 pivotally connected to the body 102, a grip portion 111 connected to the first connecting member 110 and formed with a grip, a first connecting member 110, And a second linking member 112 connecting the first and second linking members 106 and 106 to each other. For example, one end of the first connection member 110 may be pivotally connected to the body 102 or the fixing portion 104, and the grip portion 111 may be connected to the other end of the first connection member 110. The second connecting member 112 can connect the moving part 106 with the center of the first connecting member 110, preferably, the first connecting member 110. A friction material may be applied to the surface of the grip portion to which the object is gripped to improve grip performance. For example, a non-slip material, a coarse texture coating may be applied.

Further, the pair of jaws may further include a body connecting portion 114 connecting the body 102 and the grip portion 111, or more specifically, the fixing portion 104 and the grip portion 111.

According to the present invention, a cable 40 can be connected to the moving part 106. The cable 40 may be directly connected to the moving part 106 or a separate structure such as a cable latch 124 may be connected to the moving part 106 to mount the cable.

In addition, the end effector 100 according to an embodiment of the present invention may include a plurality of guide pulleys 116 on the body 102. The cable 40 may proceed from a separate configuration such as the moving portion 106 or the cable clasp 124 to be directed by the plurality of guide pulleys 116 to progress the cable 40 in a desired direction have. The cable 40 contacts at least a portion of the periphery of the plurality of guide pulleys 116 and switches its direction.

The end effector 100 according to an embodiment of the present invention may be installed at the fixed portion 104 and / or the moving portion 106 of the gripper portion 108 provided at the body 102 or spaced apart from the gripper portion 108 And stopper means 118 provided on the body 102 so as to be spaced apart from each other. An elastic member 120 is disposed between the stopper means 118 and the gripper portion 108 (or between the stopper means 118 and the fixed portion 104 and / or the moving portion 106 of the gripper portion 108) . The elastic member 120 is stretched or compressed in a direction parallel to the moving direction of the moving part 106. [

The end effector 100 according to an embodiment of the present invention may further include an elastic member guide 122 disposed on the inner surface of the elastic member 120 and connected to the stopper means 118. The stopper means, the elastic member, and the elastic member guide may be appropriately installed respectively.

The operation of the end effector according to an embodiment of the present invention will be described with reference to the following concrete examples.

3A, one or more stopper means 118 are disposed on the body 102 of the end effector, and an elastic member guide 122 is connected to one end of the stopper means 118. As shown in FIG. The elastic member 120 is connected along the elastic member guide 122 so that the elastic member 120 is configured to apply a repulsive force or attraction force between the stopper means 118 and the moving portion 106 of the gripper portion 108 .

In the present example, it is assumed that it is configured to exert a repulsive force. 2 to 3A, the gripper portion 108 includes a fixed portion 104 attached to the body 102 and a moving portion 106 moving with respect to the body 102, The gripper portion 108 or a pair of jaws may expand or contract. The elastic member 120 causes the moving part 106 to move away from the center of the end effector 100 and to move it away from the center of the end effector 100 by a plurality of cables connected to the moving part 106 or the cable latch 124 connected to the moving part 106. [ The relative movement of the moving part 106 can be realized by pulling the movable part 40. When the force is small, the elastic member 120 keeps its original length. As the force increases, the shrinkage increases. Therefore, as the total force applied to the cable increases, the moving part 106 moves much and the gripper part 108 moves .

One or more cables may be connected to the moving part 106 or the cable latch 124. The connected cable 40 may be connected to the moving part 106 or the cable latch 124 through a guide pulley 116 installed at a lower central portion of the end effector, And is moved to each corner through a plurality of guide pulleys 116 disposed at each corner of the end effector and then continuously extended and connected to the winch 20 via the pulley 50 in the frame 10 .

Referring to FIGS. 3A and 3B, the principle of driving the gripper of the end effector driven by cable tension will be described. As shown in Fig. 3A, since the force exerted by the elastic member 120 (indicated by two large arrows) is larger when the tension of the cable 40 (indicated by the small arrow) is small, The gripper portion 108 is brought into the grip releasing state, as shown in FIG. 4A, in such a manner that the force of the elastic member 120 is equal to the combined tension of the cable tension.

3B, when the cable tension (indicated by the large arrow) is large, the force applied to the cable 40 is large, so that the force of the elastic member 120 is increased and moved The portion 106 is moved downward, thereby causing the gripper portion 108 to be grasped and grasped as shown in FIG. 4B.

Figures 5A and 5B show an example of a gripper shape. It is to be appreciated that the present invention can be implemented with different configurations even if it is necessary to use a tilter or a linear movement in addition to the gripper. Various types of grippers can be used even when the gripper is used to hold an object. The end effector refers to a tool installed at the end of a robot and interacts with a work environment to perform a specific task. In addition to the embodiments described herein, the end effector may include a scissors, It should be understood that end effector configurations such as grippers, holders, staplers, etc. may also fall within the scope of the present invention.

In this specification, a widely used gripper structure is used for ease of explanation, and the following description will be made.

Referring to FIGS. 5A and 5B, the gripper includes a fixing portion 208 and a moving portion 210. The moving unit 210 may be configured to move relative to the fixed unit 208 via a driver such as a motor.

The fixed portion 208 of the gripper and the moving portion 210 are connected by a plurality of links. One end of the first link 202 is rotatably connected to the fixed portion 208 and the second link 204 is connected to one end of the moving portion 210 of the gripper and the middle end of the first link 202 Connect it so that it can rotate. The other end of the first link 202 is connected to the grip portion 212.

The third link 206 connects the grip portion 212 and the securing portion 208 and the length of the third link 206 and the first link 202 can be configured similarly, The direction does not change even if the first link 202 moves or rotates. If the length is different, a slight rotation will occur. In this gripper, when the cable tension is small so that the gripper moving portion 210 is lifted up, the second link 204 is stretched to the left and right, and as a result, the first link 202 is turned to the left and right. The third link 206 also tilts left and right like the first link 202 and thereby the gap between the grips 212 on both sides is opened.

5B, if the cable tension is large and the gripper moving part 210 is lowered, the first link 202 is pushed inward, the second link 204 is also pushed, and the distance between the grip parts 212 So that the object can be caught.

As shown in FIG. 6, the end effector 100 according to an embodiment of the present invention may employ other types of gripper portions. As shown in FIG. 6, an end effector 100 according to an embodiment of the present invention includes a body 102; A fixing part 104 installed on the body part 102; A moving part 106 movably formed with respect to the fixed part 104; A cable 40 connected to the moving part 106; A plurality of guide pulleys (116) mounted on the body portion (102) such that the cable (40) passes through at least a portion of the perimeter; A stopper means 118 formed on the body portion 102 to be spaced apart from the moving portion 106; And an elastic member 120 installed between the moving portion 106 and the stopper means 104 to be stretched or compressed.

As shown in FIG. 6, the end effector 100 according to an embodiment of the present invention may employ a gripper including a pair of jaws. One of the pair of jaws functions as a fixed part and the other of the pair of jaws functions as a moving part.

The jaws on one side of the pair of jaws connected to the body portion 102 are fixed and the jaws on the other side of the pair of jaws connected to the body portion 102 can be formed to be linearly movable with respect to the jaws on one side . The movable jaws of the other side are connected to the cable 40 so that they can move close to and move away from one side of the jaw fixed by the adjustment of the cable 40. The cable 40 can be pulled to hold the object when the moving part 106 moves close to the fixed part 104 and can hold the object when the moving part 106 moves away. An elastic member 120 is disposed between the jaws on one side of the fixing portion 104 and the other side of the moving portion 106. The jaws on one side of the fixing portion 104 function as the stopper means 118 do. The stopper means includes all the means for fixing one end of the spring. The stopper means includes not only a structure separately provided to the end effector but also a structure such as a fixed portion provided for performing other functions. The direction of the cable 40 is adjusted by the guide pulley 116 installed on the body 102.

The parallel cable robot 1 according to an embodiment of the present invention includes a frame 10 and an end effector 100 as shown in FIG. A plurality of winchs 20 capable of winding and pulling a cable can be installed in the frame 10 and a tension sensor 30 for measuring the tension of the cable wound and unwound from the nip 20 can be provided.

The operation of the components of the parallel cable robot is as follows.

The parallel cable robot 1 includes an end effector 100 for performing a specific operation and a frame 10 for securing an overall work space of the parallel cable robot 1. [ The frame 10 is provided with a plurality of winches 20 and the winch 20 is composed of a motor for driving the drum and a drum for winding the cable 40.

In addition, the parallel cable robot 1 may be mounted with the tension sensor 30 connected to the winch 20 or independently to accurately control the tension of the cable. The tensile force sensor 30 is capable of measuring the tension applied to the cable 40 as it passes over the cable 40. The cable 40 wound on the winch 20 is moved to a specific position via a plurality of pulleys 50 and continues to be connected to one end of the end effector 100.

In a conventional cable robot, a plurality of cables connect the frame and the end effector. By changing the length of the cable directly or by changing the length, it is possible to control the end effector to move to a specific position or to present the force / torque .

7, the parallel cable robot 1 according to an embodiment of the present invention may further include a control unit 80 for controlling at least one of a length and a tension of the cable. For example, the control unit may be a computer for receiving signals from the sensors and controlling at least one of a length and a tension of the cable.

The control unit 80 includes an inverse kinematics operation unit for calculating the length of the cable from the winch 20 of the frame 1 or the frame to the set target position by using inverse kinematics in order to adjust the position of the end effector 100 .

The control unit 80 may also include an equilibrium tension calculation unit for calculating the tension of the cable necessary for maintaining the balance of the end effector 100 based on the set target force or torque value required by the end effector 100 have.

The control unit 80 may further include a compensation length calculation unit for calculating a length of a cable required for operation of the end effector 100. [

Fig. 8 shows a control method of a parallel cable robot including an end effector which can be driven by cable tension.

,와 목표 힘 또는 토크,

,가 주어질 때, 목표 위치에서 역기구학을 통하여 케이블 길이의 희망 위치,

,를 우선 구한다. 동시에 목표 힘 또는 토크 값을 이용하여 엔드 이펙터가 평형적으로 머물기 위한 장력,

,를 구한다. 장력을 구할 때는 통상 목표 위치값도 활용하게 된다. 장력 값이 결정되면 그리퍼를 동작시키기 위한 보상 길이를 계산하게 된다. 보상 길이는 통상 아래와 같이 구할 수 있다. Target location,

, And target force or torque,

, Given the desired position of the cable length through inverse kinematics at the target position,

, Is first obtained. At the same time, using the target force or torque value, the tension for the end effector to stay equilibrium,

. Usually, the target position value is also used to obtain the tension. When the tension value is determined, the compensating length for operating the gripper is calculated. The compensation length is usually obtained as follows.

는 그리퍼를 움직이기 위한 그리퍼 이동부의 이동량을 의미하며,

는 케이블이 장력에 의해 늘어나게 되는 길이를 보상하는 값이다.

는 케이블의 단위길이당 탄성계수를 의미한다. 이렇게 보상 길이를 원래 케이블 길이에 추가하여 새로운 목표 길이

를 구한다. 새로운 목표 길이와 장력값을 이용하여 케이블의 위치 및 장력 제어를 수행하여 위치를 구동시킨다. 경우에 따라서 목표 힘/토크 정보를 이용한 부분은 생략이 가능하다.

Means the amount of movement of the gripper moving part for moving the gripper,

Is a value that compensates for the length at which the cable is stretched by tension.

Means the elastic modulus per unit length of the cable. By adding the compensation length to the original cable length,

. The position and tension control of the cable are performed using the new target length and the tension value to drive the position. In some cases, the portion using the target force / torque information can be omitted.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be apparent to those of ordinary skill in the art.

1: parallel cable robot 10: frame
20: winch 30: tension sensor
40: Cable 50: Pulley
80: control unit 100: end effector
102: body portion 104:
106: moving part 108: gripper part
110: first connecting member 111: grip portion
112: second connecting member 114: third connecting member
116: Guide pulley 118: Stopper means
120: elastic member 122: elastic member guide
124: cable clip 202: first link
204: second link 206: third link
208: fixing part 210: moving part
212: grip portion

Claims (4)

delete A frame provided with a winch capable of winding cables; And
And an end effector disposed in the frame, the end effector comprising: a body portion; a fixing portion provided on the body portion; a moving portion rotatably formed with respect to the fixing portion; a plurality of guide pulleys wound around the winch, And a cable driving end including an elastic member provided between the moving unit and the stopper unit and being stretched or compressed so as to be separated from the moving unit, Effector. ≪ / RTI >
The parallel cable robot according to claim 2, further comprising a controller for controlling at least one of a length and a tension of the cable. 4. The apparatus of claim 3,
An inverse kinematic operation unit for calculating a cable length from a frame to a set target position using an inverse kinematics;
An equilibrium tension calculator for calculating a tension of the cable for maintaining the balance of the end effector on the basis of a set target force or a torque value; And
And a compensation length calculator for calculating a cable length required for the operation of the end effector.

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