JP5803073B2 - Joint structure and robot having the joint structure - Google Patents

Description

  The present invention relates to a joint structure and a robot provided with the joint structure.

  As this type of technology, Patent Document 1 discloses an industrial manipulator having a pivot table, a vertical arm, a horizontal arm, a hand unit, and a gripping unit as main components and having a plurality of pivot shaft joints. A torque limiter that does not transmit an external force exceeding a predetermined value is built in the rotation shaft joint of the industrial manipulator. The torque limiter is mounted between the driven pulley and the driven shaft in a configuration in which a timing belt is wound between the driving pulley and the driven pulley, for example. In this case, the torque limiter includes a presser plate fixed to the driven shaft, a rotating plate fixed to the driven pulley, and a leaf spring that brings the presser plate and the rotating plate into a pressure-contact state with a predetermined pressing force. The According to the above configuration, the driving force is normally transmitted to the driven shaft through the driving pulley, the timing belt, the driven pulley, and the torque limiter (rotary plate, leaf spring, presser plate) in order. On the other hand, when an external force acts on the vertical arm and the external force is an impact force greater than a predetermined value, the rotational force due to the external force is transmitted to the driven shaft, but the rotational force is transmitted to the torque limiter rotating plate. It is assumed that the slip is generated between the presser plate and absorbed by the torque limiter, and the rotational force is not transmitted to the driven pulley.

Japanese Utility Model Publication No.7-686

  The torque limiter of Patent Document 1 described above is useful from the viewpoint of overload protection, but further technical improvement has been desired.

  An object of the present invention is to provide a completely new joint structure.

  According to a first aspect of the present invention, the joint structure is supported by the first member having a joint axis and the first member so as to be rotatable about the joint axis of the first member. A second member that is rotatably provided on the first member and is driven to rotate by a drive source, a driven pulley that is non-rotatably provided on the second member, the drive pulley, A transmission belt hung between the driven pulleys, and the outer periphery of the driven pulley is substantially circular, and the central axis of the driven pulley is offset from the joint axis. With the above configuration, when the relative angle of the second member with respect to the first member changes, the inter-axis distance between the rotation shaft of the driving pulley and the central shaft of the driven pulley increases or decreases. When the distance between the shafts increases or decreases, the tension of the transmission belt increases or decreases. Therefore, according to the above configuration, a configuration in which the tension of the transmission belt is increased or decreased according to the relative angle of the second member with respect to the first member is realized.

  Preferably, when a torque required for rotating the second member is large, an inter-axis distance between the rotation axis of the driving pulley and the central axis of the driven pulley increases, and the second The center axis of the driven pulley is deviated from the joint axis so that the distance between the axes becomes small when the torque required for rotating the member is small.

With the above configuration, when the torque required for rotating the second member is large, the tension of the transmission belt increases. When the tension of the transmission belt increases, the transmission belt becomes difficult to slide on the driving pulley and the driven pulley. Therefore, according to the above configuration, when a large torque is required when rotating the second member, a large torque can be transmitted without any problem.

  On the other hand, when the torque required for rotating the second member is small, the tension of the transmission belt is small. When the tension of the transmission belt is reduced, the transmission belt is easily slipped on the driving pulley and the driven pulley. Therefore, according to the above configuration, when the torque required for rotating the second member is small, only a small torque can be transmitted.

  In short, according to the above configuration, when it is necessary to transmit a large torque, the large torque is reliably transmitted, while when a large torque is not necessary, only a small torque is transmitted. A working configuration is realized.

  According to a second aspect of the present invention, the joint structure is supported by the first member having a joint axis and the first member so as to be rotatable about the joint axis of the first member. A second member that is rotatably provided on the first member and is driven to rotate by a drive source, a driven pulley that is non-rotatably provided on the second member, the drive pulley, A transmission belt hung between the driven pulleys, wherein the driven pulley includes a first portion in which a distance from the joint shaft to an outer periphery of the driven pulley is a first distance, and the driven shaft to the driven shaft. The second portion, which is the second distance, which is a distance shorter than the first distance, is located at a different position in the circumferential direction. In short, in the driven pulley, the distance from the joint shaft to the outer periphery of the driven pulley is not uniform in the circumferential direction. With the above configuration, when the relative angle of the second member with respect to the first member changes, the tension of the transmission belt increases or decreases. Therefore, according to the above configuration, a configuration in which the tension of the transmission belt is increased or decreased according to the relative angle of the second member with respect to the first member is realized.

  Preferably, when the torque required for rotating the second member is large, the first portion is in contact with the transmission belt, and the torque required for rotating the second member. The first portion and the second portion of the driven pulley are arranged so that the first portion is not in contact with the transmission belt but the second portion is in contact when the transmission belt is small. .

  With the above configuration, when the torque required for rotating the second member is large, the tension of the transmission belt increases. When the tension of the transmission belt increases, the transmission belt becomes difficult to slide on the driving pulley and the driven pulley. Therefore, according to the above configuration, when a large torque is required when rotating the second member, a large torque can be transmitted without any problem.

  On the other hand, when the torque required for rotating the second member is small, the tension of the transmission belt is small. When the tension of the transmission belt is reduced, the transmission belt is easily slipped on the driving pulley and the driven pulley. Therefore, according to the above configuration, when the torque required for rotating the second member is small, only a small torque can be transmitted.

  In short, according to the above configuration, when it is necessary to transmit a large torque, the large torque is reliably transmitted, while when a large torque is not necessary, only a small torque is transmitted. A working configuration is realized.

  Preferably, the power source is a motor provided on the first member.

  Preferably, the transmission belt is any one of a flat belt, a V belt, a toothed belt, a wire belt, and a stainless steel belt.

  According to a third aspect of the present invention, a robot includes a trunk and an arm that is rotatably connected to the trunk. The joint structure described above was applied using the trunk as the first member and the arm as the second member. Thus, the joint structure can be applied as it is between the trunk and the arm without any technical contradiction.

  According to a fourth aspect of the present invention, there is provided a trunk and an arm that is rotatably connected to the trunk. As the arm is lowered, the gap between the trunk and the arm is narrowed. The joint structure described above was applied using the trunk as the first member and the arm as the second member. That is, as the arm portion is lowered, the torque required to rotate the arm portion decreases. Further, a configuration is adopted in which the tension of the transmission belt is reduced when the torque required for rotating the arm portion is reduced. Therefore, according to the above structure, when the clearance gap between the said trunk part and the said arm part narrows, the structure which transmits only a small torque is implement | achieved.

  According to this invention, the structure which the tension | tensile_strength of the said transmission belt increases / decreases according to the relative angle of the said 2nd member with respect to the said 1st member is implement | achieved.

FIG. 1 is a front view of a robot (first embodiment). FIG. 2 is a front view of the robot (first embodiment). FIG. 3 is a perspective view of the joint structure (first embodiment). FIG. 4 is a partially cutaway perspective view of the joint structure (first embodiment). FIG. 5 is a functional block diagram of the robot control device (first embodiment). FIG. 6 is an enlarged front view of the joint structure (first embodiment). FIG. 7 is an enlarged front view of the joint structure (first embodiment). FIG. 8 is an enlarged front view of the joint structure (second embodiment). FIG. 9 is an enlarged front view of the joint structure (second embodiment).

  Hereinafter, the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the robot 1 includes a trunk 2 (first member), an upper limb 3 that is rotatably connected to the trunk 2, and a head 4 that is supported by the trunk 2. Are provided as the main components. The trunk 2, upper limb 3, and head 4 of the robot 1 correspond to a human trunk, upper limb, and head, respectively.

  The upper limb part 3 is composed of an upper arm part 5 (second member, arm part), a forearm part 6, and a grip part 7. The upper arm part 5, the forearm part 6, and the grip part 7 correspond to the human upper arm, forearm, and hand, respectively.

  The upper arm 5 is supported by the trunk 2 via the shoulder joint 8. Due to the presence of the shoulder joint portion 8, the posture of the upper arm portion 5 can be changed with respect to the trunk portion 2 as shown in FIGS. 1 and 2. FIG. 1 shows a state where the entire upper limb 3 is in a substantially horizontal posture. FIG. 2 shows a state where the entire upper limb 3 is in a lowered posture. In the present embodiment, the shoulder joint 8 is a joint with one degree of freedom.

  The forearm portion 6 is supported by the upper arm portion 5 via the elbow joint portion 9. Due to the presence of the elbow joint 9, the forearm 6 can change its posture with respect to the upper arm 5. In the present embodiment, the elbow joint 9 is a one-degree-of-freedom joint.

  The grip portion 7 is supported by the forearm portion 6 via the wrist joint portion 10. Due to the presence of the wrist joint portion 10, the gripping portion 7 can change its posture with respect to the forearm portion 6. In the present embodiment, the wrist joint 10 is a joint with two degrees of freedom.

  Next, the moment arm MA of the upper limb 3 with respect to the shoulder joint 8 will be described. 1 and 2 show the center of gravity 3g in a state where the upper limb 3 including the upper arm 5, the forearm 6, and the grip 7 is straightened. As shown in FIGS. 1 and 2, the moment arm MA increases or decreases depending on the posture of the entire upper limb 3. Specifically, the moment arm MA is large when the entire upper limb 3 is in a substantially horizontal posture as shown in FIG. 1, and the moment is large when the entire upper limb 3 is in a lowered posture as shown in FIG. Arm MA becomes smaller. The fact that the moment arm MA is large as shown in FIG. 1 means that the torque required for rotating the upper limb 3 around the shoulder joint 8 is large. On the other hand, the fact that the moment arm MA is small as shown in FIG. 2 means that the torque required for rotating the upper limb 3 around the shoulder joint 8 is small.

  Next, the joint structure J applied to the robot 1 will be described based on FIGS. 3 and 4. In the present embodiment, the joint structure J is applied to the shoulder joint portion 8 of the robot 1.

  As shown in FIGS. 3 and 4, the joint structure J includes a trunk portion 2, an upper arm portion 5, a drive pulley 11, a driven pulley 12, and a flat belt 13 (transmission belt). Yes. 3 and 4, for convenience of explanation, only a part of the trunk 2 is shown, and a part of the trunk 2 is drawn in a substantially cylindrical shape. Similarly, only a part of the upper arm 5 is shown.

  The trunk 2 has a joint 14 with a joint axis C. The joint portion 14 is formed so as to protrude from the trunk portion 2. As shown in FIG. 4, the joint portion 14 is provided with a bearing 15 that is coaxial with the joint axis C.

  The upper arm 5 is supported by the trunk 2 so as to be rotatable about the joint axis C of the joint 14 of the trunk 2.

  The drive pulley 11 is rotatably provided on the trunk 2. As shown in FIG. 4, the trunk 2 is provided with a shoulder joint drive motor 34 for rotationally driving the drive pulley 11. A reduction gear 16 is interposed between the shoulder joint drive motor 34 and the drive pulley 11. With this configuration, the torque generated by the shoulder joint drive motor 34 is amplified by the speed reducer 16 and then transmitted to the drive pulley 11. The outer periphery of the drive pulley 11 is substantially circular.

  The driven pulley 12 is provided on the upper arm 5 so as not to rotate. As shown in FIG. 4, the driven pulley 12 is fixed to the upper arm portion 5 so as not to rotate via a connecting cylindrical portion 17 formed in a cylindrical shape. The connecting cylinder portion 17 is supported by the bearing 15. In other words, the driven pulley 12 is positioned on the opposite side with the upper arm portion 5 and the joint portion 14 interposed therebetween. Due to the presence of the connecting cylinder portion 17 and the bearing 15, the upper arm portion 5 can freely rotate within a predetermined rotation angle range with respect to the trunk portion 2. In this embodiment, the outer periphery 12a of the driven pulley 12 is substantially circular as shown in FIG.

  The flat belt 13 is hung between the driving pulley 11 and the driven pulley 12.

  Next, the control device 100 provided in the robot 1 will be briefly described with reference to FIG. The control device 100 includes a central processing unit (CPU) 30 (Central Processing Unit), a readable / writable RAM 31 (Random Access Memory), and a read-only ROM 32 (Read Only Memory). The ROM 32 stores a control program. When the CPU 30 reads the control program from the ROM 32 and executes it on the CPU 30, the control program causes hardware such as the CPU 30 to function as the shoulder joint drive motor control means 33. The shoulder joint drive motor control means 33 controls the operation of the shoulder joint drive motor 34.

  Next, the joint structure J will be described in more detail based on FIGS. FIG. 6 corresponds to FIG. 1 and imagines a state in which the upper arm portion 5 is substantially horizontal. FIG. 7 corresponds to FIG. 2 and imagines a state in which the upper arm portion 5 is lowered.

  In the present embodiment, the center axis D of the driven pulley 12 is deviated from the joint axis C of the joint portion 14 in a side view of FIGS. 6 and 7 as viewed along the joint axis C of the joint portion 14. Specifically, the center axis D of the driven pulley 12 is shifted from the joint axis C of the joint portion 14 toward the elbow joint portion 9 (see also FIG. 1). In other words, the center axis D of the driven pulley 12 is shifted from the joint axis C of the joint portion 14 in the longitudinal direction of the upper arm portion 5.

  Here, as shown in FIGS. 6 and 7, the distance between the rotation axis P of the drive pulley 11 and the joint axis C of the joint portion 14 is defined as an inter-axis distance L1. Similarly, the distance between the rotation axis P of the drive pulley 11 and the center axis D of the driven pulley 12 is defined as an inter-axis distance L2. Similarly, the distance between the joint axis C of the joint portion 14 and the center axis D of the driven pulley 12 is defined as an inter-axis distance L3. Of these inter-axis distances L1 to L3, the inter-axis distance L1 and the inter-axis distance L3 are constant values. On the other hand, the inter-axis distance L2 increases or decreases according to the relative angle of the upper arm 5 with respect to the trunk 2.

  Specifically, when the upper arm 5 is in a substantially horizontal state as shown in FIG. 6, the center axis D of the driven pulley 12 sandwiches the rotation axis P of the drive pulley 11 and the joint axis C of the joint 14. Therefore, the relationship of L2 = L1 + L3 is established, and the inter-axis distance L2 is maximized. On the other hand, when the upper arm portion 5 is lowered as shown in FIG. 7, the inter-axis distance L2 is smaller than that in FIG. In the state shown in FIG. 7, the inter-axis distance L2≈the inter-axis distance L1.

  Incidentally, the tension of the flat belt 13 has a positive correlation with the inter-axis distance L2 shown in FIGS. That is, as shown in FIG. 6, the tension of the flat belt 13 increases as the inter-axis distance L2 increases, and as shown in FIG. 7, the tension of the flat belt 13 decreases as the inter-axis distance L2 decreases. Accordingly, the tension of the flat belt 13 when the upper arm portion 5 is substantially horizontal as shown in FIG. 6 is the flat belt 13 when the upper arm portion 5 is lowered as shown in FIG. Greater than the tension.

  Further, when the tension of the flat belt 13 is large, the flat belt 13 becomes difficult to slip on the driving pulley 11 and the driven pulley 12, and the upper limit of torque that can be transmitted increases. That is, when the tension of the flat belt 13 is large, a large torque can be transmitted without any problem. On the other hand, when the tension of the flat belt 13 is small, the flat belt 13 becomes slippery on the driving pulley 11 and the driven pulley 12, and the upper limit of the torque that can be transmitted is reduced. That is, when the tension of the flat belt 13 is small, only a small torque is transmitted.

  The mechanism peculiar to the joint structure J has been described above. Next, the technical significance of this joint structure J in the robot 1 shown in FIGS. 1 and 2 will be described in detail.

  As described above, when the entire upper limb 3 is in a substantially horizontal posture as shown in FIG. 1, the torque required to rotate the upper arm 5 is increased. Further, as shown in FIG. 6, when the upper arm portion 5 is in a substantially horizontal posture, a large torque can be transmitted without any problem. Therefore, as shown in FIGS. 1 and 6, when the torque required for rotating the upper arm 5 is large, large torque can be transmitted without any problem.

  Similarly, as described above, when the entire upper limb 3 is in the lowered state as shown in FIG. 2, the torque required to rotate the upper arm 5 is reduced. Further, as shown in FIG. 7, when the upper arm portion 5 is in the lowered state, only a small torque is transmitted. Therefore, as shown in FIGS. 2 and 7, when the torque required for rotating the upper arm 5 is small, only a small torque is positively transmitted.

  Reference is now made to FIG. As shown in FIG. 2, in the state where the entire upper limb 3 is lowered, the gap G between the trunk 2 and the upper limb 3 (including the upper arm 5) is narrowed. Therefore, when the entire upper limb part 3 is lowered, a person or an object is caught in the gap G between the trunk part 2 and the upper limb part 3, and there is a risk of applying pressure. Therefore, according to the joint structure J described above, in the state shown in FIG. 2, the flat belt 13 is configured to transmit only a small torque from the driving pulley to the driven pulley. Therefore, even when a person or an object is sandwiched in the gap G between the trunk 2 and the upper limb part 3 when the entire upper limb part 3 is lowered, excessive pressure is not applied to the person or the object.

  On the other hand, according to the joint structure J, as described above, when the torque required for rotating the upper arm portion 5 is large, a large torque can be transmitted without any problem.

(Summary)
The preferred first embodiment of the present invention has been described above, but the first embodiment has the following features in summary.

  The joint structure J according to the first embodiment includes a trunk part 2 having a joint axis C, an upper arm part 5 supported by the trunk part 2 so as to be rotatable around the joint axis C of the trunk part 2, and a trunk part. 2, a drive pulley 11 that is rotatably provided by a shoulder joint drive motor 34 (drive source), a driven pulley 12 that is provided so as not to rotate on the upper arm 5, and between the drive pulley 11 and the driven pulley 12. And a flat belt 13 (transmission belt) that is hung on the belt. The outer periphery 12a of the driven pulley 12 is substantially circular. The center axis D of the driven pulley 12 is offset from the joint axis C. With the above configuration, when the relative angle of the upper arm 5 with respect to the trunk 2 changes, the inter-axis distance L2 between the rotation axis P of the drive pulley 11 and the center axis D of the driven pulley 12 increases or decreases. When the inter-axis distance L2 increases or decreases, the tension of the flat belt 13 increases or decreases. Therefore, according to the above configuration, a configuration in which the tension of the flat belt 13 is increased or decreased according to the relative angle of the upper arm 5 with respect to the trunk 2 is realized.

  In the first embodiment, the transmission belt is the flat belt 13, but instead of this, any one of a V belt, a toothed belt, a wire belt, and a stainless steel belt may be used.

  In the first embodiment, the power source is the shoulder joint drive motor 34 provided in the trunk 2, but is not limited to this.

  Further, when the torque required for rotating the upper arm 5 is large, the inter-axis distance L2 between the rotation axis P of the drive pulley 11 and the center axis D of the driven pulley 12 is increased, and the upper arm 5 is rotated. The center axis D of the driven pulley 12 is deviated from the joint axis C so that the inter-axis distance L2 is reduced when the torque required for the operation is small.

  With the above configuration, when the torque required for rotating the upper arm 5 is large, the tension of the flat belt 13 is large. When the tension of the flat belt 13 increases, the flat belt 13 becomes difficult to slide on the driving pulley 11 and the driven pulley 12. Therefore, according to the above structure, when the torque required when rotating the upper arm part 5 is large, a large torque can be transmitted without a problem.

  On the other hand, when the torque required to rotate the upper arm 5 is small, the tension of the flat belt 13 is small. When the tension of the flat belt 13 is reduced, the flat belt 13 is easily slipped on the driving pulley 11 and the driven pulley 12. Therefore, according to the above configuration, when the torque required for rotating the upper arm portion 5 is small, only a small torque can be transmitted.

  In short, according to the above configuration, when it is necessary to transmit a large torque, the large torque is reliably transmitted, while when a large torque is not necessary, only a small torque is transmitted. A working configuration is realized.

  The robot 1 includes a trunk 2 and an upper arm 5 (arm) that is rotatably connected to the trunk 2. The robot 1 is applied with a joint structure J including a trunk 2 and an upper arm 5. Thus, the joint structure J can be applied as it is between the trunk 2 and the upper arm 5 without technical contradiction.

  The robot 1 also includes a trunk 2 and an upper arm 5 that is rotatably connected to the trunk 2. As the upper arm portion 5 is lowered, the gap G between the trunk portion 2 and the upper arm portion 5 is narrowed. The robot 1 is applied with a joint structure J including a trunk 2 and an upper arm 5. That is, as the upper arm portion 5 is lowered, the torque required to rotate the upper arm portion 5 decreases. Further, a configuration is adopted in which the tension of the flat belt 13 is reduced when the torque required for rotating the upper arm portion 5 is reduced. Therefore, according to the above configuration, when the gap G between the trunk 2 and the upper arm 5 is narrowed, a configuration in which only a small torque is transmitted is realized.

  Although the main features of the joint structure J according to the present embodiment have been described above, the joint structure J is also a simple structure, can be realized in a light weight, and can reduce the cost because a so-called pinching detection sensor can be omitted. There is also an advantage of being able to plan. Further, when the tension of the flat belt 13 is increased, the flat belt 13 is strongly restricted from extending further. Accordingly, in the state of FIG. 1, the upper limb 3 is hardly shaken by the external force.

  Furthermore, since the driven pulley 12 is provided on the upper arm portion 5 on the output side, the so-called joint shaft can be hollowed as shown in FIG.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. Here, the present embodiment will be described with a focus on differences from the first embodiment, and overlapping descriptions will be omitted as appropriate. In addition, in principle, the same reference numerals are assigned to components corresponding to the respective components of the first embodiment.

  In the above embodiment, the driven pulley 12 has an outer periphery 12a formed in a substantially circular shape, and the joint axis C of the joint portion 14 and the center axis D of the driven pulley 12 are shifted as shown in FIG. On the other hand, in the driven pulley 12 according to the present embodiment, the distance from the joint axis C of the joint portion 14 to the outer periphery 12a of the driven pulley 12 is not uniform in the circumferential direction. Specifically, the driven pulley 12 includes a protruding portion 12b (first portion) having a first distance B1 (first distance) from the joint axis C of the joint portion 14 to the outer periphery 12a of the driven pulley 12, and a joint. An arc portion 12c (second portion) in which the distance from the joint axis C of the portion 14 to the outer periphery 12a of the driven pulley 12 is a second distance B2 (second distance) that is shorter than the first distance B1; At different positions in the circumferential direction. In the present embodiment, the arc portion 12c is formed at a position 90 degrees different from the protruding portion 12b about the joint axis C counterclockwise.

  And when the torque required when rotating the upper arm part 5 as shown in FIG. 8 is large, the protrusion part 12b contacts with the flat belt 13, and when rotating the upper arm part 5 as shown in FIG. When the required torque is small, the protruding portion 12b does not contact the flat belt 13, but the protruding portion 12b and the arc portion 12c of the driven pulley 12 are arranged so that the arc portion 12c contacts.

(Summary)
The preferred second embodiment of the present invention has been described above, but the second embodiment has the following features in summary.

  The driven pulley 12 has a protruding portion 12b where the distance from the joint axis C to the outer periphery 12a of the driven pulley 12 is the first distance B1, and the distance from the joint axis C to the outer periphery 12a of the driven pulley 12 is greater than the first distance B1. The circular arc part 12c which is the second distance B2 which is a short distance is provided at different positions in the circumferential direction. In short, in the driven pulley 12, the distance from the joint axis C to the outer periphery 12a of the driven pulley 12 is not uniform in the circumferential direction. With the above configuration, when the relative angle of the upper arm 5 with respect to the trunk 2 changes, the tension of the flat belt 13 increases or decreases. Therefore, according to the above configuration, a configuration in which the tension of the flat belt 13 is increased or decreased according to the relative angle of the upper arm 5 with respect to the trunk 2 is realized.

  Further, when the torque required for rotating the upper arm 5 as shown in FIG. 8 is large, the protruding portion 12b comes into contact with the flat belt 13, and when the upper arm 5 is rotated as shown in FIG. When the required torque is small, the projecting portion 12b and the arc portion 12c of the driven pulley 12 are arranged so that the projecting portion 12b does not contact the flat belt 13 but the arc portion 12c contacts.

  With the above configuration, when the torque required for rotating the upper arm 5 is large, the tension of the flat belt 13 is large. When the tension of the flat belt 13 increases, the flat belt 13 becomes difficult to slide on the driving pulley 11 and the driven pulley 12. Therefore, according to the above structure, when the torque required when rotating the upper arm part 5 is large, a large torque can be transmitted without a problem.

  On the other hand, when the torque required to rotate the upper arm 5 is small, the tension of the flat belt 13 is small. When the tension of the flat belt 13 is reduced, the flat belt 13 is easily slipped on the driving pulley 11 and the driven pulley 12. Therefore, according to the above configuration, when the torque required for rotating the upper arm portion 5 is small, only a small torque can be transmitted.

  In short, according to the above configuration, when it is necessary to transmit a large torque, the large torque is reliably transmitted, while when a large torque is not necessary, only a small torque is transmitted. A working configuration is realized.

1 Robot 2 Trunk (first member)
3 upper limbs (arms)
5 Upper arm (arm)
11 Drive pulley 12 Driven pulley 13 Flat belt (power transmission belt)
C Joint axis
D Driven pulley center shaft
P Drive pulley rotating shaft 100 Controller

Claims (4)

A trunk having a joint axis;
An arm portion supported by said torso so as to be rotatable on the joint axis of the torso,
A drive pulley that is rotatably provided in the trunk and is driven to rotate by a drive source;
A driven pulley provided in the arm so as not to rotate;
A transmission belt hung between the drive pulley and the driven pulley;
With
The outer periphery of the driven pulley is substantially circular,
When the arm is in a substantially horizontal posture and the torque required to rotate the arm is large, the distance between the rotation axis of the drive pulley and the center axis of the driven pulley is Grow,
When the arm portion is in a lowered state and the torque required for rotating the arm portion is small, the inter-axis distance is reduced.
The central axis of the driven pulley is offset from the joint axis;
Joint structure. A trunk having a joint axis;
An arm supported by the trunk so as to be rotatable about the joint axis of the trunk;
A drive pulley that is rotatably provided in the trunk and is driven to rotate by a drive source;
A driven pulley provided in the arm so as not to rotate;
A transmission belt hung between the drive pulley and the driven pulley;
With
In the driven pulley, a distance from the joint shaft to the outer periphery of the driven pulley is a first distance, and a distance from the joint shaft to the outer periphery of the driven pulley is shorter than the first distance. A second portion that is a second distance that is a distance, and a different position in the circumferential direction,
The arm portion is in a substantially horizontal posture, and when the torque required for rotating the arm portion is large, the first portion is in contact with the transmission belt,
When the arm portion is in a lowered state and the torque required for rotating the arm portion is small, the first portion does not contact the transmission belt, but the second portion is To make contact
The first part and the second part of the driven pulley are arranged;
Joint structure. The joint structure according to claim 1 or 2 ,
The drive source is a motor provided on the trunk .
Joint structure. The joint structure according to any one of claims 1 to 3 ,
The transmission belt is a flat belt, a V belt, a toothed belt, a wire belt, or a stainless steel belt,
Joint structure.

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