KR20180097423A - Robot arm equipped with counterbalance mechanism - Google Patents

Abstract

A robot arm according to the present invention comprises: a first link; a second link having a second link main body connected to the first link with a first pitch joint, and a second link joint body rotationally connected to the second link main body; a third link connected to the second link and a second pitch joint; a first pitch joint drive unit supported on the first link to rotate the second link about the first pitch joint; a second pitch joint drive unit supported on the second link to rotate the third link about the second pitch joint; a first auxiliary link rotationally connected to the first link and the second link joint body, respectively, for connecting the first link and the second link joint body; and a second link auxiliary link rotationally connected to the first link and the second link joint body, respectively, to constitute a quadruple link together with the first link, the second link joint body and the first auxiliary link.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a robot arm having a gravity compensation device,

The present invention relates to a robot arm, and more particularly, to a robot arm having a gravity compensation device capable of canceling a gravity torque applied to a joint by the self weight of the robot arm when the robot arm is held and driven.

Currently, in various industrial fields, process automation is actively performed to improve the efficiency, and accordingly, the importance of a robot arm that can be flexibly used in various operations is increasing. Robot arm is used for various works such as transportation, assembling, welding, coloring of heavy objects, and various sizes of robot arm have been developed and used according to the target work.

When the robot arm maintains its posture or drives it, a gravity torque due to the weight of the robot arm is applied to the joint connecting the link in the gravity direction. As the robot arm becomes larger, the magnitude of the gravitational torque becomes larger and a large driving force is required for the joint. Therefore, a large-sized robot arm is required to have a large-capacity motor and a reducer, which increases manufacturing cost and power consumption. In order to solve this problem, various methods of canceling mechanical gravity torque by using a gravity compensating device using a weight or spring are applied to a joint of a robot arm.

In the simplest case, there is a method of using a 1-degree-of-freedom gravity compensator using a weight or a spring. However, this 1 - degree - of - freedom gravity compensator has limitations in applying to a robot arm of multiple degrees of freedom.

In order to overcome these limitations, a multi-degree-of-freedom gravity compensator using a parallel four-bar linkage structure has been proposed. However, there is a problem that the range of motion of the joint is limited to less than 180 degrees due to the dead point of the parallel four-bar linkage structure of the parallel four-bar link structure. In addition, the conventional parallel four-bar link-based robot arm also has the disadvantage that an additional link protrudes from the outside of the body, thereby increasing the volume of the robot arm.

To solve these problems, a multi-degree-of-freedom gravity compensator has been proposed which uses wire and belt-pulley to minimize joints and minimize volume. However, this method has problems due to low durability and reproducibility of wire and belt. Therefore, there is a need for an invention of a multi-degree-of-freedom gravity compensator having sufficient durability and reproducibility without harming the range of motion of the joint.

Patent Registration No. 1190228 (Oct. 12, 2012) Patent Registration No. 1270031 (Feb. 31, 2013)

SUMMARY OF THE INVENTION It is an object of the present invention to provide a gravity compensator that is capable of providing a wide range of motion and excellent durability and minimizing the torque applied to a joint by using a multi-degree of freedom gravity compensator having a high durability and a wide movable range And a robot arm provided with a gravity compensation device.

According to an aspect of the present invention, there is provided a robot arm comprising: a first link; A second link main body coupled to the first link by a first pitch joint and a second link joint body rotatably coupled to the second link main body; A third link connected to the second link with a second pitch joint; A first pitch joint drive part supported on the first link to rotate the second link about the first pitch joint; A second pitch joint drive part supported on the second link to rotate the third link about the second pitch joint; A first auxiliary link rotatably connected to the first link and the second link joint body, respectively, for connecting the first link and the second link joint body; And a second auxiliary link rotatably connected to the first link and the second link joint body respectively and constituting a quadric link together with the first link, the second link joint body and the first auxiliary link, .

And the rotational center axis of the second link joint body with respect to the second link main body may be located on the second pitch joint.

The robot arm according to the present invention is preferably such that the longitudinal direction of the second link main body, the longitudinal direction of the first auxiliary link, and the longitudinal direction of the second auxiliary link are all parallel.

Wherein the second link main body is provided with an inner space and the second link joint body is rotatably disposed inside the second link main body, 2 link main body.

The robot arm according to the present invention may further include a first counter balancer supported on the first link to support a load of the second link to compensate gravity torque in the first pitch joint.

Wherein the first counterbalance comprises a first connecting rod rotatably connected to any one of the first link and the second link and a second counter connecting rod rotatably connected to the first connecting rod, A first slider movably installed in the other one of the links and interlocked with the movement of the first connecting rod; and a second slider that elastically biases the first slider in a direction opposite to a direction in which the first connecting rod pulls the first slider And a first elastic member connected to the first slider.

Wherein the first counter balancer further includes a first support frame coupled to one of the first link and the second link, the first elastic member is coupled to the first support frame, and the first slider And may be slidably coupled to the first support frame.

The first counterbalancer may further include a first guide bar coupled to the first support frame so as to extend in a sliding direction of the first slider, and the first elastic member may include a spring structure The first slider may be slidably coupled to the first guide bar so as to compress the first elastic member.

The robot arm according to the present invention may further include a second counter balancer supported on the second link to support a load of the third link to compensate gravity torque in the second pitch joint.

The second counter balancer includes a second connecting rod rotatably connected to any one of the second link and the third link and a second connecting rod rotatably connected to the second connecting rod, A second slider movably installed on the other one of the links and interlocked with the movement of the second connecting rod; and a second slider, which applies elastic force to the second slider in a direction opposite to a direction in which the second connecting rod pulls the second slider And a second elastic member connected to the second slider.

Wherein the second counterbalancer further comprises a second support frame coupled to one of the second link and the third link, the second elastic member is coupled to the second support frame, and the second movable member May be slidably coupled to the second support frame.

The second counterbalancer further includes a second guide bar coupled to the second support frame to extend in a sliding direction of the second slider, and the second elastic member has a spring structure And the second slider may be slidably coupled to the second guide bar so as to compress the second elastic member.

The second connecting rod of the second counterbalancer may be connected to the second link joint body of the second link.

The robot arm according to the present invention may further include a wrist portion connected to the third link with a third pitch joint and having a plurality of wrist links connected to a wrist joint.

The robot arm according to the present invention may further include a base jointed to the first link through a base joint having a rotation center axis perpendicular to a rotation center axis of the first pitch joint.

The robot arm according to the present invention has a size, durability, and operation range similar to that of a general robot arm by applying a dual parallel four-bar link-based multi-degree-of-gravity compensator to a pitch joint, It is possible to minimize the magnitude of the torque required for maintaining the posture and driving. Therefore, the manufacturing cost of the robot arm can be lowered by using the low-capacity motor and the speed reducer, and the energy consumption can be reduced by using much less energy to perform the same operation.

In addition, the robot arm according to the present invention can provide a compensating torque to the link mechanism by a counter balancer including an elastic member for providing an elastic force, a slider for transmitting the elastic force of the elastic member, and a connecting rod, You can compensate. Therefore, it is possible to reduce the load that should be generated in the joint driving part by not providing the torque for canceling the gravity torque from the joint driving part, and to cope with a larger load using the same output joint driving part, Joint drive parts can be used.

In addition, the robot arm according to the present invention can maximize payload by implementing gravity compensation using a counter balancer having a simple structure, and reduces the torque load on the joints, thereby minimizing the turning force. And the capacity of joint drive parts such as motors and speed reducers can be greatly reduced.

In addition, the robot arm according to the present invention can stabilize gravity compensation through a counterweight balancer having a simple structure, and enable a compact structure, thereby maximizing utilization in various fields.

1 is a perspective view of a robot arm having a gravity compensation device according to an embodiment of the present invention.
FIG. 2 illustrates a robot arm having a gravity compensation device according to an embodiment of the present invention.
3 is a perspective view of a robot arm having a gravity compensation device according to an embodiment of the present invention.
FIG. 4 illustrates a gravity compensation apparatus according to an embodiment of the present invention. Referring to FIG.
5 and 6 are exploded perspective views illustrating a connection structure of a first link and a second link of a robot arm having a gravity compensation device according to an embodiment of the present invention.
FIGS. 7 to 10 are exploded perspective views illustrating a connection structure between a second link and a third link of a robot arm having a gravity compensation device according to an embodiment of the present invention.
11 and 12 show a concrete configuration of a first counter balancer of a robot arm provided with a gravity compensation device according to an embodiment of the present invention.
13 and 14 show a concrete configuration of a second counter balancer of a robot arm having a gravity compensation device according to an embodiment of the present invention.
15 is a simplified conceptual diagram for explaining the operation principle of the gravitational compensation apparatus of a robot arm having a gravity compensation apparatus according to an embodiment of the present invention.
16 is a graph showing a compensation torque according to a joint rotation angle when a design parameter is appropriately selected to explain an effect of a gravity compensation device for a robot arm having a gravity compensation device according to an embodiment of the present invention.
FIG. 17 is a conceptual diagram for explaining the structure and principle of a single parallel four-bar link-based multi-degree-of-gravity compensation apparatus in connection with a robot arm having a gravity compensation apparatus according to an embodiment of the present invention.
FIGS. 18 and 19 are conceptual diagrams for explaining the configuration and principle of a dual parallel four-bar link-based multi-degree-of-gravity compensation apparatus of a robot arm provided with a gravity compensation apparatus according to an embodiment of the present invention.
20 is a conceptual diagram showing an extended range of operation of the dual parallel four-bar link based multi-degree of freedom gravity compensation apparatus shown in FIG. 18;

Hereinafter, a robot arm having a gravity compensation device according to the present invention will be described in detail with reference to the drawings.

As shown in the drawing, a robot arm 100 having a gravity compensation device according to an embodiment of the present invention includes a base 102, a first link 110 connected to the base 102 via a base joint Jb A second link 120 connected to the first link 110 through a first pitch joint Jp1 and a third link 140 connected to the second link 120 through a second pitch joint Jp2, A wrist 180 connected to the third link 140 through a third pitch joint Jp3 and a gravity compensator 150 for compensating for gravity torque.

The robot arm 100 according to the present embodiment has a multi-joint structure in which a plurality of links are connected to each other by a plurality of joints. The joint structure includes a roll (base joint) pitch Joints) - Pitch (2nd pitch joint) 3 main joints and 3 wrist joints (3rd pitch joint, 1st deciduous joint, 2nd wrist joint) to determine the direction of the robot end. And a spring-based gravity compensation device 150 is mounted to perform gravity compensation for the two pitch joints (first pitch joint, second pitch joint) at which the gravity torque is greatest. The robot arm 100 adopts a double parallel four-bar link structure, and a double parallel four-bar link works with the gravity compensator 150 to enable multi-degree of freedom gravity compensation.

The base 102 is connected to the first link 110 via the base joint Jb. When the base 102 is fixed to the floor, the rotation center axis on the base joint Jb can be disposed perpendicular to the floor. A base joint drive part (not shown) capable of rotating the first link 110 around the base joint Jb may be installed on the base 102.

The first link 110 is coupled to the base 102 so as to rotate about the base joint Jb. The first link 110 includes a first link base body 111, a first link main body 112, and a first link sub body 113. The first link base body 111 is disposed in parallel with the upper surface of the base 102 and is rotatably coupled to the base 102. The first link main body 112 is disposed on the upper surface of the first link base body 111 so as to be substantially perpendicular to the first link base body 111 so as to rotatably support the second link 120. The first link sub-body 113 is disposed on the upper surface of the first link base body 111 so as to face the first link main body 112. One end of the second link 120 is positioned between the first link main body 112 and the first link sub-body 113.

The first link 110 is provided with a plurality of first link pivot joints 114, 115, and 116. The first link pivot connection part 114 of one of the plurality of first link pivot connection parts 114, 115 and 116 is for connection of the first auxiliary link 137 and the other one of the first link pivot connection part 114, The first link pivot connection part 116 is for connecting the second auxiliary link 138 and the other first link pivot connection part 116 is for connecting the first connecting rod 160 provided in the first counter balancer 151, .

The first link 110 may be modified to various other structures that are connected to the base 102 and the base joint Jb and may be connected to the second link 120 by the first pitch joint Jp1, .

The second link 120 is connected to the first link 110 by a first pitch joint Jp1 so as to be rotatable with respect to the first link 110. [ The rotation center axis on the first pitch joint Jp1 is perpendicular to the rotation center axis on the base joint Jb. The second link 120 includes a second link main body 121, a second link sub body 124, and a second link joint body 126. The second link 120 is connected to the center of the first pitch joint Jp1 by the first pitch joint driving part 135 which is rotatably coupled to the first link 110 and is supported by the first link 110, .

The first pitch joint drive part 135 is supported by the first link main body 112 of the first link 110 and has various structures for providing the driving force for rotating the second link 120 to the second link 120. [ . The connection structure between the first pitch joint drive part 135 and the first link 110 and the connection structure between the first pitch joint drive part 135 and the second link 120 are changed to various other structures .

The second link main body 121 includes a second link main body drive frame 122 and a second link main body link frame 123 coupled with the second link main body drive frame 122. The second link main body driving frame 122 is connected to the first pitch joint driving part 135 and rotated about the first pitch joint Jp1 by the first pitch joint driving part 135. [ The second link main body connection frame 123 is rotatably connected at both ends to the first link 110 and the third link 140, respectively. The rotational force of the first pitch joint driving part 135 is transmitted to the second link main body connecting frame 123 through the second link main body driving frame 122 when the first pitch joint driving part 135 is operated, The link main body connection frame 123 can rotate about the first pitch joint Jp1. A second link body 126 and a pair of auxiliary links 137 and 138 are accommodated in the space inside the second link main body connection frame 123.

The second link sub-body 124 is coupled to the second link main body connection frame 123, one end of the second link sub-body 124 is rotatably coupled to the first link 110, At the other end of the link sub-body 124, a portion of the third link 140 is rotatably engaged.

The second link joint body 126 is rotatably coupled to the end of the second link main body 121 to which the third link 140 is connected. The rotational center axis of the second link joint body 126 with respect to the second link main body 121 is located on the second pitch joint Jp2. The second link joint body 126 includes a main joint body 127, a sub joint body 128, and a joint joint body 129.

The main joint body 127 is rotatably coupled to the end of the second link main body connection frame 123. The sub joint body 128 is coupled to the main joint body 127 so as to face each other. A space is provided between the main joint body 127 and the sub joint body 128 so that the ends of the first sub link 137 and the second sub link 138 can be positioned. The joint body 129 is coupled to the sub-joint body 128. The main joint body 127 and the sub joint body 128 are accommodated in the space between the second link main body 121 and the second link sub body 124 of the second link 120 and the joint joint body 129 Is disposed outside of the second link sub-body 124 and is connected to the sub-joint body 128 through a through hole provided in the second link sub-body 124. The connecting joint body 129 is connected to the second counter balancer 162.

The second link 120 is provided with a plurality of second link pivot joints 131, 132 and 133. One of the plurality of second link pivot connection portions 131, 132 and 133 is for connection with the first auxiliary link 137 and is provided on the main joint body 127 And the other second link pivot connection part 132 is disposed on the main joint body 127 for connection with the second auxiliary link 138. The second link pivot connection part 133 is provided on the connection joint body 129 for connection with the second connecting rod 171 of the second counter balancer 162. The second link pivot joint 133 to which the second connecting rod 171 is connected is positioned eccentrically from the rotational center axis of the second link joint body 126.

A first auxiliary link 137 and a second auxiliary link 138 are installed inside the second link 120. These auxiliary links 137 and 138 connect the first link 110 and the second link joint body 126. The first auxiliary link 137 is rotatably connected to the first link 110 via the first link pivot connection part 114 of the first link 110 and the other end is rotatably connected to the second link joint body 126 to the second link joint body 126 through a second link pivot connection 131 of the first link joint 126. [ The second auxiliary link 138 is rotatably connected to the first link 110 via the first link pivot connection part 115 of the first link 110 and the other end is rotatably connected to the second link joint body 115 126 to the second link joint body 126 through a second link pivot connection 132 of the first link joint 126. [ Accordingly, the first auxiliary link 137 and the second auxiliary link 138 together form the four-link link together with the first link 110 and the second link joint body 126.

The longitudinal direction of each of the first auxiliary link 137 and the second auxiliary link 138 is parallel to the longitudinal direction of the second link main body 121. 18, the first link 110, the second link 120, the second link joint body 126, and the pair of auxiliary links 137 138 are arranged in a double parallel 4 Link structure.

The robot arm 100 according to the present embodiment can form a parallelogram mechanism through the double parallel four-bar link structure as described above. The parallelogram mechanism is a parallelogram mechanism composed of a link and a joint, and serves to maintain a predetermined angle with respect to the ground on the basis of the link determined as a reference during the joint motion of the link mechanism. By matching the reference plane for the multi-degree-of-freedom link mechanism through the parallelogram mechanism, the gravity compensation torque can be minimized and the operation can be performed quickly. That is, as shown in Fig. 18, the same rotation standard can be formed by maintaining the same rotation state in the two pitch joints Jp1 and Jp2 through the parallelogram mechanism. Therefore, even if the second link 120 rotates about the first pitch joint Jp1, the second link joint body 126 can form another reference plane having a certain angle with the ground, and the second pitch joint Jp2 ) Is possible.

The second link 120 may be connected to the first link 110 by a first pitch joint Jp1 and may be connected to the third link 140 by a second pitch joint Jp2, Structure. The second link joint body 126 of the second link 120 is also rotatably coupled to the second link main body 121 and the pair of auxiliary links 137 and 138 and the second connecting rod 171 are rotatably coupled, Various other structures can be connected. Also, the double parallel four-bar link structure by the second link 120 and the pair of auxiliary links 137 and 138 is not limited to the illustrated one, and can be variously changed.

The third link 140 is connected to the second link 120 through the second pitch joint Jp2 so as to be rotatable with respect to the second link 120. [ The rotation center axis on the second pitch joint Jp2 is parallel to the rotation center axis on the first pitch joint Jp1. The third link 140 includes a third link main body 141 and a third link sub body 142 coupled with the third link main body 141. The third link 140 is connected to the second pitch joint Jp2 by a second pitch joint driving part 145 whose one end is rotatably coupled to the second link 120 and is supported by the second link 120 And can rotate about the center.

The second pitch joint drive unit 145 may have various structures that can be supported by the second link 120 and provide a driving force for rotating the third link 140 to the third link 140. [ The connection structure between the second pitch joint drive part 145 and the second link 120 and the connection structure between the second pitch joint drive part 145 and the third link 140 may be changed to various other structures .

The third link main body 141 is connected to the second pitch joint drive part 145 and receives the driving force from the second pitch joint drive part 145 and rotates around the second pitch joint Jp2. The third link sub-body 142 is rotatably coupled to the second link sub-body 124 so as to face the third link main body 141 with one end of the second link main body 121 therebetween.

The wrist portion 180 is connected to the third link 140 at a third pitch joint Jp3 so as to be rotatable with respect to the third link 140. [ The wrist 180 can rotate about the third pitch joint Jp3 by the third pitch joint driving part 185. [ The third pitch joint drive part 185 may be supported by the third link 140 and may have various structures capable of providing driving force for rotating the wrist part 180 to the wrist part 180.

The wrist portion 180 includes a first wrist link 181 rotatably coupled to the third link 140 and a second wrist link 181 connected to the first wrist link 181 and the first wrist joint Jw1. 182 and a third wrist link 183 connected by a second wrist link 182 and a second wrist joint Jw2. The third wrist link 183 may be provided with an end effector (not shown), which may be implemented as a roll motor or a gripper.

The wrist portion 180 may be modified into various other structures that are articulably connected to the third link 140 in addition to the structure shown.

The gravity compensator 150 includes a first counter balancer 151 that is supported on the first link 110 to apply an elastic force to the second link 120 to compensate gravity torque at the first pitch joint Jp1, And a second counter balancer 162 that is supported on the second link 120 to apply an elastic force to the third link 140 to compensate gravity torque at the second pitch joint Jp2. The first counter balancer 151 and the second counter balancer 162 utilize the elastic force. The first counter balancer 151 and the second counter balancer 162 are different from each other in installation position and gravity compensated joint, and their overall structure and function are similar.

11 and 12, the first counterbalancer 151 includes a first support frame 152 fixed to the second link 120, a first elastic member supported by the first support frame 152 A first slider 156 movably installed on the first support frame 152 and a first connecting rod 160 connecting the first slider 156 and the first link 110 do.

The first support frame 152 is coupled to the second link main body 121 of the second link 120. The first support frame 152 may be detachably coupled to the second link main body 121 through a fixing member such as a screw or a bolt. The first support frame 152 is provided with a guide rail 153 for guiding the movement of the first slider 156.

One pair of the first elastic members 154 are spaced apart from each other on the first support frame 152. A pair of guide bars 155 are provided on the first support frame 152 for the installation of the first elastic member 154. These guide bars 155 are arranged parallel to each other at a constant spacing. The first elastic member 154 has a spring structure wound around the outer periphery of the guide bar 155.

The first slider 156 is slidably mounted on the first support frame 152. The first slider 156 can reciprocate linearly along the guide rails 153 of the first support frame 152. The first slider 156 includes a pressing portion 157 that is slidably coupled to the pair of guide bars 155 and a connecting portion 157 that is connected to the pressing portion 157 and is slidably coupled to the guide rail 153, And a rod connection portion 158. A slider pivot connection portion 159 for coupling the first connecting rod 160 is provided at one side of the connecting rod connecting portion 158. The first slider 156 is moved by the first connecting rod 160 so that the first elastic member 154 can be resiliently deformed by the pressing portion 157.

The first connecting rod 160 connects the first link 110 and the first slider 156. One end of the first connecting rod 160 is rotatably connected to the first link pivot connecting portion 116 of the first link 110 and the other end of the first connecting rod 160 is connected to the slider pivot connecting portion 159 of the first slider 156 And is rotatably connected. The first link pivotal connection 116 of the first link 110 is positioned eccentrically from the rotational center axis on the first pitch joint Jp1.

As the second link 120 rotates relative to the first link 110 the first support frame 152 moves with the second link 120 so that the first connecting rod 160 moves in the first And rotates around the first link pivotal connection 116 of the link 110. At this time, the first connecting rod 160 pulls the first slider 156 to compress the first elastic member 154 so that the elastic force of the first elastic member 154 is transmitted to the first slider 156 156 and the first connecting rod 160 to the second link 120. Therefore, the gravity torque can be compensated in the first pitch joint Jp1 when the second link 120 rotates, and the driving torque of the first pitch joint driving part 135 for moving the second link 120 can be reduced have.

The first counterbalancer 151 can take a modular structure that is assembled through a fixing member such as a screw. When the components of the first counter balancer 151 are repaired or replaced, the first counter balancer 151 is connected to the first link 110 and the second link 110 120, and can be easily assembled. Therefore, it is possible to save time and cost for maintenance work.

The first counterbalancer 151 may be supported by the first link 110 so that the first counterbalancer 151 is supported by the first link 110 to apply an elastic force to the second link 120, By supporting the load, it can be changed to various other structures capable of compensating gravity torque at the first pitch joint Jp1.

For example, the first support frame 152 of the first counterbalancer 151 is coupled to the second link main body 121 of the second link 120, 1 link 110 but the first support frame is coupled to the first link 110 and the first connecting rod is connected to the second link 120 The structure is also possible. In addition, the first elastic member can be changed to another structure capable of providing an elastic force in addition to the coil spring structure as shown in the drawing, and the structure and connection of the first slider and the first connecting rod, which transmit the elastic force of the first elastic member, The structure can also be varied in various ways.

13 and 14, the second counter balancer 162 includes a second support frame 163 fixed to the third link 140, a second elastic member 163 supported on the second support frame 163, A second slider 167 movable in the second support frame 163 and a second connecting rod 171 connecting the second slider 167 and the second link 120 do.

The second support frame 163 is coupled to the third link main body 141 of the third link 140. The second support frame 163 may be detachably coupled to the third link main body 141 through a fixing member such as a screw or a bolt. The second support frame 163 is provided with a guide rail 164 for guiding the movement of the second slider 167.

The pair of second elastic members 165 are installed on the second support frame 163 so as to be spaced apart from each other. A pair of guide bars 166 are provided on the second support frame 163 for the installation of the second elastic member 165. These guide bars 166 are spaced apart from one another by a predetermined distance. The second elastic member 165 has a spring structure wound around the outer periphery of the guide bar 166.

The second slider 167 is slidably mounted on the second support frame 163. The second slider 167 can reciprocate linearly along the guide rail 164 of the second support frame 163. The second slider 167 includes a pressing portion 168 slidably coupled to the pair of guide bars 166 and a connecting portion 168 connected to the pressing portion 168 and slidably coupled to the guide rail 164, And a load connection portion 169. At one side of the connecting rod connecting portion 169, a slider pivot connecting portion 170 for coupling the second connecting rod 171 is provided. The second slider 167 is moved by the second connecting rod 171 and can be elastically deformed by pressing the second elastic member 165 with the pressing portion 168.

The second connecting rod 171 connects the second link 120 and the second slider 167. One end of the second connecting rod 171 is rotatably connected to the second link pivot connecting portion 133 of the second link 120 and the other end of the second connecting rod 171 is connected to the slider pivot connecting portion 170 of the second slider 167 And is rotatably connected. The second link pivot joint 133 of the second link 120 is provided on the joint joint body 129 of the second link joint body 126 so as to be eccentric from the rotational center axis on the second pitch joint Jp2.

When the third link 140 rotates about the second link 120 the second support frame 163 moves with the third link 140 so that the second connecting rod 171 moves in the second And rotates around the second link pivotal connection 133 of the link 120. At this time, the second connecting rod 171 pulls the second slider 167 so that the second slider 167 compresses the second elastic member 165, and the elastic force of the second elastic member 165 is transmitted to the second slider 167 and the second connecting rod 171 to the third link 140. Therefore, the gravity torque can be compensated in the second pitch joint Jp2 when the third link 140 rotates, and the driving torque of the second pitch joint driving part 145 for moving the third link 140 can be reduced have.

The second counterbalancer 162 can take a modular structure that is assembled through a fixing member such as a screw. When the parts of the second counter balancer 162 are repaired or replaced by replacing the second counter balancer 162 with the second link 120 and the third link balancer 162, 140, and can be easily assembled. Therefore, it is possible to save time and cost for maintenance work.

The second counterbalancer 162 is supported on the second link 120 to apply an elastic force to the third link 140 so that the second counterbalancer 162 is supported on the second link 120, By supporting the load, it can be changed into various other structures that can compensate for the gravity torque at the second pitch joint Jp2.

For example, in the figure, the second support frame 163 of the second counterbalancer 162 is coupled to the third link main body 141 of the third link 140, and the second connecting rod 171 2 link 120 and the second supporting frame is coupled to the second link 120 and the second connecting rod is connected to the third link 140 The structure is also possible. Further, the second elastic member can be changed to another structure capable of providing an elastic force in addition to the coil spring structure as shown in the drawing, and the structure of the second slider and the second connecting rod, which transmit the elastic force of the second elastic member, The structure can also be varied in various ways.

The robot arm 100 according to the present embodiment employs a dual parallel four-bar linkage structure and a spring-based gravity compensation device 150, thereby minimizing gravity compensation torque and enabling effective gravity torque compensation.

Hereinafter, the principle of gravity compensation of the robot arm 100 according to the present embodiment will be described.

First, the principle of the gravity compensation device 150 applied to the present embodiment will be described with reference to FIG. 15 is a simplified conceptual diagram for explaining the operation principle of the spring-based gravity compensation device.

The spring-based gravity compensation device includes an elastic member (hereinafter referred to as a spring), a slider, and a connecting rod. Since the position of the rotation shaft is R by the link and the connecting rod, the connecting rod compresses the spring by moving the slider as the link rotates. The compression distance s of the spring according to the rotation angle of the link is s, where k, s, s0, and lcr are the spring constant, the total compression distance of the spring, the initial compression distance of the spring, and the length of the connecting rod.

The elastic force Fs and the compensating torque? C, which are generated according to the deformation length s, can be expressed as follows.

,

,

On the other hand, when the link rotates by?, The gravity torque? G applied to the joint is as follows.

Where l is the distance from the center of rotation of the link to the center of mass of the link.

By appropriately setting the four design parameters R, k, s0, and lcr so that the magnitude of the compensation torque? C approximates the gravity torque? G, the gravity torque? G appearing in a sinusoidal shape along the link rotation can be canceled. 16 is a graph for canceling the gravity torque? G which occurs when m = 3.8 kg and l = 300 mm with the compensating torque generated when R is 36 mm, lcr = 65 mm, k = 6.54 N / mm, and s0 = 36 mm.

Meanwhile, the multi-degree-of-freedom gravity compensation for two pitch joints can be realized by a single parallel four-bar linkage structure as shown in FIG. At this time, a sinusoidal gravity torque is applied to each joint as follows.

,

,

Where m2 and m3 are the mass of each link, lc2 and lc3 are the distance from the rotation center of each link to the center of gravity, l2 is the distance between the pitch joints as the length of link 2, Is a rotation angle with respect to a reference plane perpendicular to gravity. As shown in the figure, the spring-based gravity compensating device 1 and the gravity compensating device 2 are respectively installed on the link 2 and the link 3 to apply the compensation torque generated by the elastic force of the spring between each link and the reference surface, . In this case, the reference planes must always be perpendicular to the ground in order for the multi-degree-of-freedom gravity compensator to generate the compensation torque of appropriate magnitude, and each joint should not affect the rotation of each other. Link 2, auxiliary link, reference plane 1, and reference plane 2 have a parallel four-bar linkage structure. By satisfying this condition, appropriate gravity compensation for each joint is possible.

However, a single parallel four-bar link-based multi-degree-of-freedom gravity compensator as shown in Fig. 17 has a disadvantage in that there is a limitation of the joint range by a dead point of a parallel four-bar link. Therefore, all of the robotic arms that have a parallel four-link link have narrow range of joints less than 180 degrees in the corresponding joints.

In order to solve this problem, in order to solve this problem, as shown in FIG. 18, a second link 120 and a first auxiliary link 137 and a second auxiliary link 138 are arranged in parallel with the vertical reference plane 1 and the reference plane 2 for gravity, Parallel four-bar link structure is used. The rotation axes of the first auxiliary link 137 and the second auxiliary link 138 are at positions perpendicular to each other with respect to the second link 120 so that a pair of parallel four- A point at which the link and the first auxiliary link overlap), the reference plane 2 is kept perpendicular to the ground by the other pair of parallel four-bar link structures. As a result, the double parallel four-bar link structure does not have a point. Accordingly, the robot arm 100 according to the present embodiment has an extended joint range of 180 degrees or more as shown in FIG.

As described above, in the robot arm 100 according to the present embodiment, the first pitch joint Jp1 and the second pitch joint Jp2, which are greatly influenced by the gravity torque, By applying the compensating device 150, it is possible to minimize the size of the torque required for maintaining the posture and driving while having a size, durability and movable range similar to those of a general robot arm. Therefore, the manufacturing cost of the robot arm 100 can be reduced by using the low-capacity motor and the speed reducer, and the energy consumed for performing the same operation can be reduced, thereby reducing the operation cost.

Reference numerals 191 to 193 denote a link cover coupled to the second link 120 or the third link 140 and reference numerals 194 and 195 denote a first counter balancer 151 or a second counter balancer 162 of the counter balancer cover.

Although the preferred embodiments of the present invention have been described above, the scope of the present invention is not limited to those described and illustrated above.

For example, in the figure, a link mechanism in which a robot arm 100 includes a first link 110, a second link 120, and a third link 140 is rotatably supported on the base 102, The wrist 180 of the multi-joint is connected to the end of the third link 140. However, the number of links and joints constituting the robot arm of the present invention can be variously changed.

A parallelogram mechanism may also be provided between the second link 120 and the third link 140 via an auxiliary link.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Those skilled in the art will appreciate that numerous modifications and variations can be made in the present invention without departing from the spirit and scope of the appended claims.

100: robot arm 102: base 102
110: first link 111: first link base body
112: first link main body 113: first link sub-body
114 to 116: First link pivot connection part 120: Second link
121: Second link main body
122: second link main body drive frame
123: Second link main body connection frame
124: second link sub-body 126: second link joint body
127: main joint body 128: sub joint body
129: joint body 131-133: second link pivot connection
135: first pitch joint drive unit 137, 138: first and second auxiliary links
140: third link 141: third link main body
142: Third link sub-body 145: Second pitch joint drive part
150: gravity compensation device 151, 162: first and second counter balancers
152, 163: first and second support frames 153, 164: guide rails
154, 165: first and second elastic members 155, 166: guide bar
156, 167: first and second sliders 157, 168:
159, 169: connecting rod connecting portion 159: 170: slider pivot connecting portion
160, 171: first and second connecting rods 180: wrist
181 to 183: first, second and third wrist links 185: third pitch joint drive part
191 to 193: Link cover 194, 195: Counter balancer cover
Jb: Base joints Jp1 to Jp3: 1st, 2nd and 3rd pitch joints
Jw1, Jw2: 1st and 2nd wrist joints

Claims (15)

A first link;
A second link main body coupled to the first link by a first pitch joint and a second link joint body rotatably coupled to the second link main body;
A third link connected to the second link with a second pitch joint;
A first pitch joint drive part supported on the first link to rotate the second link about the first pitch joint;
A second pitch joint drive part supported on the second link to rotate the third link about the second pitch joint;
A first auxiliary link rotatably connected to the first link and the second link joint body, respectively, for connecting the first link and the second link joint body; And
And a second auxiliary link rotatably connected to the first link and the second link joint body respectively and constituting a quadric link together with the first link, the second link joint body and the first auxiliary link Wherein the robot arm is a robot arm.
The method according to claim 1,
And a rotation center axis of the second link joint body with respect to the second link main body is positioned on the second pitch joint.
The method according to claim 1,
The longitudinal direction of the second link main body, the longitudinal direction of the first auxiliary link, and the longitudinal direction of the second auxiliary link are all parallel.
The method of claim 3,
Wherein the second link main body is provided with an inner space and the second link joint body is rotatably disposed inside the second link main body, 2 link main body of the robot arm.
The method according to claim 1,
And a first counter balancer supported on the first link to support a load of the second link to compensate gravity torque in the first pitch joint.
6. The method of claim 5,
Wherein the first counter balancer comprises:
A first connecting rod rotatably connected to one of the first link and the second link and a second connecting rod rotatably connected to the other one of the first link and the second link And a first slider connected to the first slider so as to exert an elastic force on the first slider in a direction opposite to a direction in which the first connecting rod pulls the first slider, And a second elastic member provided on the first elastic member.
The method according to claim 6,
Wherein the first counter balancer further includes a first support frame coupled to one of the first link and the second link, the first elastic member is coupled to the first support frame, and the first slider And the second arm is slidably coupled to the first support frame.
8. The method of claim 7,
The first counterbalancer may further include a first guide bar coupled to the first support frame so as to extend in a sliding direction of the first slider, and the first elastic member may include a spring structure Wherein the first slider is slidably coupled to the first guide bar so as to compress the first elastic member.
The method according to claim 1,
And a second counter balancer supported on the second link to support a load of the third link to compensate gravity torque in the second pitch joint.
10. The method of claim 9,
Wherein the second counter balancer comprises:
A second connecting rod rotatably connected to one of the second link and the third link and a second connecting rod rotatably connected to the other of the second link and the third link And a second slider connected to the second slider so as to apply an elastic force to the second slider in a direction opposite to a direction in which the second connecting rod pulls the second slider, And a second resilient member provided on the other end of the second resilient member.
11. The method of claim 10,
Wherein the second counterbalancer further comprises a second support frame coupled to one of the second link and the third link, the second elastic member is coupled to the second support frame, and the second movable member Is slidably coupled to the second support frame.
12. The method of claim 11,
The second counterbalancer further includes a second guide bar coupled to the second support frame to extend in a sliding direction of the second slider, and the second elastic member has a spring structure And the second slider is slidably coupled to the second guide bar so as to compress the second elastic member.
11. The method of claim 10,
And the second connecting rod of the second counterbalancer is connected to the second link joint body of the second link.
The method according to claim 1,
And a wrist portion connected to the third link with a third pitch joint and having a plurality of wrist links connected to the wrist joints.
The method according to claim 1,
And a base jointed to the first link through a base joint having a rotation center axis perpendicular to a rotation center axis of the first pitch joint.

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