Robot sub-arm mechanism

Abstract

To perform, with a relatively simple and inexpensive configuration, work in cooperation with a main end effector and an auxiliary tool.SOLUTION: A sub-arm mechanism 11 of a robot, which is attached to a robot body 1 including a plurality of arms 4-9 and configured to perform work by attaching an end effector 10 to a hand tip part 9 thereof and which includes a sub-work tool 12 configured to perform an auxiliary operation of the end effector 10, includes: a moving arm mechanism 13 whose basal end part is supported by an intermediate arm 6 of the robot body 1 and that holds the sub-work tool 12, and moves the sub-work tool such that it follows the hand tip part 9 according to a change in posture of the robot body 1; and a posture maintaining mechanism 14 that maintains a constant posture of the sub-work tool 12 moved by the moving arm mechanism 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sub-arm mechanism of a robot that is attached to a robot body and has a sub-work tool that performs auxiliary operations of an end effector. [Background technology]

[0002] In recent years, harvesting robots have been developed for automatically harvesting agricultural products such as fruits. This type of harvesting robot is equipped with, for example, a six-axis articulated robot body on an autonomous travelling platform, and is configured by attaching a harvesting hand equipped with a cutting blade mechanism for cutting the stalk of a fruit as an end effector to the tip of the arm of the robot body (see, for example, Patent Document 1).

[0003] In this case, in order for the harvesting robot to harvest fruit without damaging or dropping it, it is desirable to not only cut the fruit stalk with the harvesting hand, but also to place an auxiliary tool, such as a harvesting basket, below the fruit to catch the dropped fruit. In other words, it is necessary to perform the main work using the harvesting hand in coordination with an auxiliary work using another tool. Such a cooperative work can be realized, for example, by employing a dual-arm robot equipped with two arms. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-37214 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when using a dual-arm robot to perform collaborative work, the robot body of almost two units is required, which leads to a significant increase in cost, and the overall size and installation space are increased. In addition, since it is necessary to operate the two arms without interfering with each other, there are problems such as complicated control and limitations on the range of motion of the arms.

[0006] It is possible to attach two sets of end effectors to the tip of the arm of a single robot body to perform a task, but this would result in problems such as the weight of the tip of the arm becoming larger and the moment of inertia becoming larger, making it difficult to operate at high speed. The present invention has been made in consideration of the above circumstances, and its object is to provide a robot sub-arm mechanism that enables work to be performed through cooperation between a main end effector and an auxiliary tool, and that can be realized with a relatively simple and inexpensive configuration. [Means for solving the problem]

[0007] The sub-arm mechanism (11, 31, 41) of the robot described in claim 1 is attached to a robot body (1) having a multi-axis arm (4-9) with an end effector (10) attached to its hand (9) to perform work, and is equipped with a sub-work tool (12) that performs auxiliary operations of the end effector, and is equipped with a moving arm mechanism (13) whose base end is supported by an intermediate arm of the robot body, holds the sub-work tool, and moves it to follow the hand in response to changes in posture of the robot body, and a posture maintaining mechanism (14, 32, 42) that maintains a constant posture of the sub-work tool moved by the moving arm mechanism.

[0008] In the above configuration, the sub work tool can be moved by the moving arm mechanism to follow the movement of the hand of the robot main body while its posture is maintained by the posture maintaining mechanism. The movement of the arm beyond the intermediate arm to which the support arm is attached can be performed regardless of the sub work tool, and the end effector can move independently. This allows the sub work tool to perform robot work while always maintaining a fixed position relative to the end effector at the tip of the arm.

[0009] In this case, the sub work tool can be moved following the end effector by changing the posture of the robot body without using a dual-arm, so a simple configuration can be achieved at low cost. Also, since the sub arm mechanism can be supported by a highly rigid part of the robot body, the weight of the arm tip can be kept small. A separate drive source for operating the sub arm is no longer required, and arm control becomes easier. As a result, it becomes possible to perform work through the cooperation of the main end effector and auxiliary tool, and this can be achieved with a relatively simple and inexpensive configuration. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a state in which a sub-arm mechanism is attached to a robot main body according to a first embodiment. [Diagram 2] FIG. 1 is a perspective view of the end effector in an upward movement state; [Diagram 3] FIG. 1 is a perspective view showing a state in which the end effector is moved downward; [Figure 4] 1 is a perspective view of a state in which the shoulder portion is rotated to the right [Diagram 5] 1 is a perspective view showing a state in which the shoulder portion is rotated to the left; [Figure 6] Top view showing the tip side of the robot body [Figure 7] Side view of the end effector moved to the upper level [Figure 8] Side view showing the standard posture of the robot body [Figure 9] Side view of the end effector moved to the lower middle section [Figure 10] Side view of the end effector moved to the lower level [Figure 11] Rear perspective view of the end effector [Figure 12] FIG. 13 is a perspective view showing a state in which the main body of the end effector is rotated; [Figure 13] FIG. 13 is a perspective view showing a state in which a sub-arm mechanism is attached to a robot body according to a second embodiment. [Figure 14] FIG. 13 is a perspective view showing a state in which a sub-arm mechanism is attached to a robot body according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, several embodiments of the present invention will be described with reference to the drawings. Each of these embodiments is applied to a 6-axis vertical articulated robot that performs, for example, fruit harvesting. In each of the embodiments described below, the same reference numerals are used for parts that are equivalent to those described in the preceding embodiments, and new illustrations and duplicated explanations will be omitted.

[0012] (1) First embodiment A first embodiment will be described with reference to Figs. 1 to 12. Fig. 1 and other figures show a state in which a sub-arm mechanism 11 according to this embodiment is attached to a robot body 1. First, the robot body 1 will be described. This robot body 1 is configured with a six-axis arm of a well-known configuration on a base 3, and the base 3 is mounted on an automatic traveling cart (not shown). Figs. 1 and 8 show the standard posture of the robot body 1, and when referring to the front, back, left and right of the robot body 1, this posture will be used as a reference and the side facing an end effector described later will be described as the front. Therefore, Figs. 7 to 10 are right side views.

[0013] The arms of each axis of the robot main body 1 are connected to be rotatable in sequence via joints as follows: That is, a shoulder section 4 as a one-axis arm is connected to the base 3 to be rotatable about a rotation axis J1 extending vertically. A lower end of a lower arm 5 as a two-axis arm extending upward in Fig. 1 is connected to the upper end of the shoulder section 4 to be rotatable in the vertical direction about a rotation axis J2 extending horizontally. A base end of an intermediate arm 6 as a three-axis arm is connected to the tip of the lower arm 5 to be rotatable in the vertical direction about a rotation axis J3 extending horizontally.

[0014] An upper arm 7 as a four-axis arm is connected to the tip of the intermediate arm 6, extending in the same axial direction as the intermediate arm 6, so as to be coaxially rotatable about a rotation axis J4. A wrist section 8 as a five-axis arm is connected to the tip of the upper arm 7 so as to be movable up and down about a rotation axis J5. A flange section 9 as a hand section, i.e. a six-axis arm, is connected to the tip of the wrist section 8 so as to be coaxially rotatable about a rotation axis J6. An end effector 10 is attached to the tip surface of the flange 9.

[0015] Although detailed description will be omitted, the end effector 10 is, for example, a harvesting hand, and is configured to include a base member, a gripping mechanism for gripping the stalk of a fruit, a cutting blade mechanism for cutting the stalk, and a motor that drives these mechanisms. Furthermore, in this embodiment, as shown in Figures 11 and 12, the end effector 10 is provided with an operating member 21 located at the base of the end effector 10 and extending to the left. This operating member 21 is configured to tilt and displace a sub work tool, which will be described later, by rotating the flange portion 9 of the robot main body 1 and therefore the end effector 10 about a rotation axis J6.

[0016] Although not shown, servo motors for driving each axis are built into the robot body 1, and the servo motors for each axis are energized and controlled by the robot controller while the rotational position is detected by an encoder. Also, although not shown, the robot body 1 is provided with a camera for photographing the harvested product, and the position of the fruit stalk is automatically detected from the photographed image. The robot controller, end effector 10, and automatic traveling cart are driven and controlled by a control device mainly composed of a computer, and are configured to automatically perform fruit harvesting work.

[0017] A sub-arm mechanism 11 equipped with a sub-work tool 12 that performs auxiliary operations for the end effector 10 is attached to the robot body 1 described above. In this embodiment, for example, a harvesting basket is provided as the sub-work tool 12. This sub-work tool 12 consisting of a harvesting basket works in coordination with the end effector 10, that is, works in cooperation with the end effector 10, to receive below the fruit whose stalk has been cut off by the end effector 10. The detailed structure of the sub-arm mechanism 11 will be described below.

[0018] The sub-arm mechanism 11 according to this embodiment roughly comprises a moving arm mechanism 13 which moves the sub work tool 12 in accordance with a change in the posture of the robot main body 1, following the flange portion 9, which is the hand portion, or end effector 10, and a posture maintaining mechanism 14 which maintains a constant posture of the sub work tool 12. The moving arm mechanism 13 comprises a support arm 15 and a swing arm 16. The posture maintaining mechanism 14 comprises a first parallel link mechanism 17 and a second parallel link mechanism 18.

[0019] At this time, two sets of the support arm 15, swing arm 16, first parallel link mechanism 17 and second parallel link mechanism 18 constituting the moving arm mechanism 13 and the posture maintaining mechanism 14 are provided symmetrically on the left and right sides of the robot main body 1, and the sub work tool 12 is supported in a so-called double-supported state by the two swing arms 16. The moving arm mechanism 13 and the posture maintaining mechanism 14 will be described in detail below.

[0020] The support arm 15 constituting the moving arm mechanism 13 is shaped like a thin lever, and its base end side, i.e., the rear end side in the figure, is fixedly attached to the side of the base end part of the intermediate arm 6, which is a three-axis arm located in the middle of the robot main body 1. The tip side of this support arm 15 extends in the same direction as the extension direction of the intermediate arm 6 and upper arm 7, i.e., the front-to-rear direction in Figure 1 etc. The tip end of this support arm 15 and the base end part of the swing arm 16 are rotatably connected at a connection part 19.

[0021] This swing arm 16 is also shaped like a thin lever, with its tip extending downward in Fig. 1. In this case, a joint 19 that rotatably joins the support arm 15 and the swing arm 16 is provided at a position that coincides or nearly coincides with a rotation axis J5 of a joint between the upper arm 7 and the wrist 8 of the robot main body 1 when the said axis J5 is held horizontal. In other words, the joint 19 is always disposed to the side of the wrist 8, which is the hand end of the robot main body 1.

[0022] The sub work tool 12 is attached to the lower end of the front part of the swing arm 16. As shown in Figures 11 and 12, the sub work tool 12 has a main body 12a, for example in the shape of a thin rectangular container with an open top, for receiving the harvested crops. The front half of the bottom of the main body 12a is configured as a slope that gently slopes downward to the rear. A shaft member 12b (see Figure 11) is provided in the center of the rear wall of the main body 12a so as to protrude horizontally to the rear. Furthermore, an outlet 12c for discharging the harvested crops is provided on the right side wall of the main body 12a.

[0023] Meanwhile, a mounting plate 22 is provided at the front of the two swing arms 16 so as to span between them from the left to the right. The shaft member 12b is rotatably supported by the mounting plate 22, and the main body 12a of the sub work tool 12 is provided so as to be rotatable about an axis extending in the front-rear direction. As shown in Figs. 1 to 5, the sub work tool 12 is located directly below the end effector 10 of the robot body 1, and is arranged with a predetermined gap in the vertical direction. During normal work, the sub work tool 12 is located in a normal position where it receives harvested crops, with the main body 12a horizontal to the mounting plate 22. The rotational movement of the main body 12a will be described later.

[0024] On the other hand, the posture maintaining mechanism 14 is configured as follows. That is, as shown in Figs. 1 to 5 and 7 to 10, the first parallel link mechanism 17 has a configuration in which four links are connected by rotatable joints in order to form a parallelogram. In this case, the first parallel link mechanism 17 has a slightly elongated shape having long and short sides, and a base end link 17a, which is one of the short sides, is fixedly attached to the lower side of the side of the shoulder part 4, which is a single-axis arm on the base end side of the robot body 1, so as to be horizontal. The first parallel link mechanism 17 extends upward along the side of the robot body 1, and a horizontal tip link 17b facing the base end link 17a is disposed behind the upper part of the lower arm 5 of the robot body 1.

[0025] The second parallel link mechanism 18 also has a configuration in which four links are connected by rotatable joints in order to form a parallelogram having long and short sides, and a base end link 18a, which is one of the short sides, extends in the vertical direction and is arranged overlapping and fixedly connected to the tip link 17b of the first parallel link mechanism 17 so as to form a cross. The second parallel link mechanism 18 extends forward, and a tip link 18b facing the base end link 18a is connected to the lower rear end of the swing arm 16 in a state of extending in the vertical direction.

[0026] In the sub-arm mechanism 11 configured as described above, as shown in Fig. 1 etc., the sub work tool 12 supported by the sub-arm mechanism 11 is positioned below the end effector 10, and in this state, the robot main body 1 automatically performs work, for example, fruit harvesting. At this time, the sub work tool 12 can be moved by the moving arm mechanism 13 in accordance with the movement of the hand end portion of the robot main body 1, i.e., the flange portion 9, while the attitude maintaining mechanism 14 maintains the attitude of the sub work tool 12, i.e., a constant attitude facing horizontally upward. In this case, in the robot main body 1, the hand end portion can be moved up and down or back and forth mainly by the movement of the shoulder portion 4 and lower arm 5, i.e., by changing the attitude.

[0027] 1 and 8, the shoulder 4 is rotated about the rotation axis J2 and the lower arm 5 is rotated about the rotation axis J3, changing the posture of the robot body 1 to a state in which the hand, i.e., the end effector 10, is elevated. Then, as shown in Fig. 2, in the moving arm mechanism 13, the position of the joint 19 also rises as the wrist 8 etc. rise. As a result, the swing arm 16 is swung so as to reduce the bending angle with respect to the support arm 15, and the sub work tool 12 rises following the end effector 10.

[0028] At the same time, in the posture maintaining mechanism 14, the tip side of the first parallel link mechanism 17, i.e., tip link 17b, moves rearward of the lower arm 5, and the tip side of the second link mechanism 18, i.e., tip link 18b, rises, maintaining the downward posture of the swing arm 16, and therefore a constant posture of the sub work tool 12. Figure 7 shows a state in which the robot body 1 has been operated to move the end effector 10 further upward from the state shown in Figure 2, and again the sub work tool 12 is moved so as to maintain its position relative to the end effector 10, without changing its horizontal posture.

[0029] 1 and 8, the shoulder section 4 is rotated about the rotation axis J2 and the lower arm 5 is rotated about the rotation axis J3 to change the position of the hand section, i.e., the end effector 10, in the moving arm mechanism 13, the position of the coupling section 19 also descends as the flange section 9 etc. descends, as shown in Figure 3, and further Figure 9 or Figure 10. This causes the swing arm 16 to swing so as to widen the bending angle with respect to the support arm 15, and the sub work tool 12 descends following the end effector 10.

[0030] At the same time, in the posture maintaining mechanism 14, the tip side of the first parallel link mechanism 17, i.e., tip link 17b, moves forward, and the tip side of the second link mechanism 18, i.e., tip link 18b, descends. This maintains the downward posture of the swing arm 16 relative to the end effector of the robot main body 1, and therefore the horizontal posture of the sub work tool 12 and its position spaced downward. In this way, the sub work tool 12 can be moved in response to the movement of the end effector of the robot main body 1.

[0031] 4 shows the robot body 1 with the shoulder part 4 rotated to the right, i.e., clockwise as viewed from above, from the standard position about the rotation axis J1. Fig. 5 shows the robot body 1 with the shoulder part 4 rotated to the left, i.e., clockwise as viewed from above, from the standard position about the rotation axis J1. Even when the shoulder part 4 is moved in this way, the sub-arm mechanism 11 moves following the robot body 1, and the horizontal attitude of the sub work tool 12 and its relative position spaced downward from the robot body 1 are maintained.

[0032] Furthermore, in the above configuration, as shown in Fig. 6, the upper arm 7, wrist section 8, and flange section 9 beyond the intermediate arm 6 to which the support arm 15 is attached can each move independently of the sub work tool 12. In other words, the coaxial rotation of the upper arm 7 about its rotation axis J4 relative to the intermediate arm 6 in the direction of arrow A, the pivoting of the wrist section 8 about its rotation axis J5 relative to the upper arm 7 in the direction of arrow B, and the coaxial rotation of the flange section 9 about its rotation axis J6 relative to the wrist section 8 in the direction of arrow C can be freely performed without interfering with or affecting the sub arm mechanism 11 or the sub work tool 12. The end effector 10 can also move independently.

[0033] As described above, the sub-work tool 12 is provided so as to be movable, i.e., tiltable, between a normal position in which the main body 12a is horizontal as shown in Fig. 11 and a recovery position in which the main body 12a is tilted downward with the right side as viewed from the front to discharge the harvested crops from the outlet 12c as shown in Fig. 12. Therefore, in this embodiment, the entire main body 12a is a movable part. Also, the main body 12a is always biased to the normal position by a biasing means such as a spring (not shown).

[0034] A lever 20 for rotating the main body 12a is provided on the rear wall of the main body 12a and extends upward. Meanwhile, an operating member 21 for rotating the lever 20 is provided on the base of the end effector 10 and extends leftward. Thus, during normal operation of the end effector 10, the operating member 21 is separated from the lever 20 and does not interfere with it, and the main body 12a is positioned in the normal position to receive the harvested crops.

[0035] In contrast, during recovery work to collect harvested products, for example, in a collection container, the sub-work tool 12 is moved above the collection container, and in that state, the flange portion 9 of the robot main body 1, and therefore the end effector 10, are rotated counterclockwise about the rotation axis J6, causing the operating member 21 to rotate the lever 20 and tilt the main body portion 12a to the recovery position. Therefore, in this embodiment, the main body portion 12a, as the movable part, is operated by the end effector 10 of the robot main body.

[0036] As described above, the sub-arm mechanism 11 of this embodiment can provide the following actions and effects. That is, the sub-arm mechanism 11 of this embodiment is configured to include a moving arm mechanism 13 that moves the sub work tool 12 in accordance with the movement of the hand part of the robot main body 1, and a posture maintaining mechanism 14 that maintains the posture of the sub work tool 12, so that the sub work tool 12 can be operated while always maintaining a fixed position relative to the end effector 10 at the tip of the robot main body 1. At this time, the upper arm 7 and subsequent arms of the robot main body 1 can move regardless of the sub work tool 12, and the end effector 10 can move freely on its own.

[0037] In this case, the sub work tool 12 can be moved following the end effector 10 by the operation of the robot main body 1, so there is no need for a complex and large structure such as a double arm, and a simple, small and inexpensive structure can be achieved. Also, since the sub arm mechanism 11 can be supported by a part of the robot main body 1 that has a relatively high rigidity, the weight of the arm tip of the robot main body 1 can be kept small. Furthermore, there is no need for a separate drive source to operate the sub work tool 12, making control easier.

[0038] As a result, according to this embodiment, the sub-arm mechanism 11, which enables work to be performed through cooperation between the main end effector 10 and the auxiliary sub-work tool 12, has the excellent effect of being realized with a relatively simple and inexpensive configuration. In particular, in this embodiment, the robot main body 1 is configured with a six-axis arm, so that it is possible to easily cause the sub-work tool 12 to perform auxiliary work while performing work with a high degree of freedom as a whole.

[0039] In this embodiment, two sets of moving arm mechanisms 13 and attitude maintaining mechanisms 14 are provided symmetrically on both sides of the robot main body 1, and the sub work tool 12 is supported by the two swing arms 16 in a double-supported state. This increases the rigidity of the sub arm mechanism 11, enabling stable operation of the sub work tool 12. Furthermore, in this embodiment, the tilting operation of the main body part 12a, which serves as the movable part of the sub work tool 12, can be performed by the robot main body 1, making it possible to perform a wider variety of tasks while eliminating the need for a separate drive source.

[0040] (2) Second embodiment 13 shows the second embodiment, which differs from the first embodiment in the configuration of the sub-arm mechanism 31. That is, the sub-arm mechanism 31 is configured to include a moving arm mechanism 13 and a posture maintaining mechanism 32. The posture maintaining mechanism 32 also includes a first parallel link mechanism 17 and a second parallel link mechanism 18. In this case, the first parallel link mechanism 17 is provided with a redundant intermediate link bar 33 that connects the intermediate portions of the opposing base end link 17a and tip end link 17b, and is provided with an adjustable length.

[0041] In this case, although not shown, a screw structure such as a turnbuckle is provided in the middle of the intermediate link bar 33 to allow the length to be adjusted. Similarly, in the second parallel link mechanism 18, a redundant intermediate link bar 34 that connects the middle parts of the opposing base end link 18a and tip end link 18b is provided with a screw structure such as a turnbuckle so that the length can be adjusted.

[0042] According to the second embodiment, by providing the intermediate link bars 33, 34, it is possible to increase the rigidity of the first parallel link mechanism 17 and the second parallel link mechanism 18, and in turn the rigidity of the entire sub-arm mechanism 31. At this time, since the intermediate link bars 33, 34 are adjustable in length, it is possible to correct the play of each joint of the parallel link mechanisms 17, 18. Note that, although the intermediate link bars 33, 34 are provided in both the first parallel link mechanism 17 and the second parallel link mechanism 18 in this example, an intermediate link bar may be provided in either one of the first parallel link mechanism 17 or the second parallel link mechanism 18.

[0043] (3) Third embodiment and other embodiments 14 shows the third embodiment, in which the configuration of a posture maintaining mechanism 42 of a sub-arm mechanism 41 is different from that of the first embodiment. That is, the posture maintaining mechanism 42 also includes a first parallel link mechanism 17 and a second parallel link mechanism 18. An encoder 43 for posture detection is provided at a joint where a front end of a base end link 17a of the first parallel link mechanism 17 is connected to a lower end of a long side link. Furthermore, an encoder 44 for posture detection is provided at a joint where a lower end of a tip link 18b of the second parallel link mechanism 18 is connected to a front end of a long side link.

[0044] These encoders 43, 44 are, for example, rotary encoders, and are configured to detect variations in the angles of the joints to which they are attached. With this configuration, it is possible to detect the presence or absence of an abnormality in the positions and postures of the arms 4 to 9 of the robot body 2 based on the angles of the joints of the parallel link mechanisms 17, 18 being detected by the encoders 43, 44. For example, if an abnormality is detected in the correspondence between the posture of the robot body 1 and the angles of the joints of the parallel link mechanisms 17, 18, it is possible to determine that an abnormality has occurred in either one of them, and to safely stop the robot body 1.

[0045] In the first embodiment described above, the lever 20 of the sub work tool 12 is operated by the actuating member 21 provided on the end effector 10 on the robot main body 1 to tilt the main body 12a. Alternatively, the sub work tool may be provided with an actuator that can operate independently of the robot main body 1, such as a motor, air drive, solenoid, etc., so that the sub work tool itself performs the required operation. This enables the sub work tool to operate independently, making it possible to carry out a wider variety of tasks.

[0046] In addition, in each of the above embodiments, a robot that harvests fruit or the like has been described as a specific example, but the robot can be used in a wide range of applications other than agriculture, such as a robot that processes chemicals, a robot that performs surgery in the medical field, or a robot that paints, solders, or the like in the industrial field. More specifically, various tasks are possible, such as assisting a surgical robot with a sub-work tool, processing or assembling a workpiece with an end effector while the sub-work tool holds the workpiece, or painting an object while masking it without contact with the workpiece with the sub-work tool. In this case, various tools such as a hand can be used as the end effector.

[0047] In addition, the configuration of the robot body is not limited to a 6-axis vertical articulated robot, but can also be applied to other robots such as a 4-axis horizontal articulated robot. Furthermore, it goes without saying that various modifications are possible with regard to the specific configuration of the swing arm mechanism and the attitude maintenance mechanism. Although the present disclosure has been described based on the embodiment, it is understood that the present disclosure is not limited to the embodiment or structure. The present disclosure also includes various modified examples and modifications within the equivalent range. In addition, various combinations and forms, and even other combinations and forms including only one element, more than one element, or less than one element, are also within the scope and concept of the present disclosure. [Explanation of symbols]

[0048] In the drawings, 1 is a robot main body, 3 is a base, 4 is a shoulder portion (arm on the base end side), 6 is an intermediate arm (middle arm), 8 is a wrist portion, 9 is a flange portion (hand portion), 10 is an end effector, 11, 31, 41 are sub-arm mechanisms, 12 is a sub work tool, 12a is a main body portion (movable portion), 13 is a moving arm mechanism, 14, 32, 42 are posture maintenance mechanisms, 15 is a support arm, 16 is a swinging arm, 17 is a first parallel link, 18 is a second parallel link, 19 is a connecting portion, 20 is a lever, 21 is an operating member, 33, 34 are intermediate link bars, 43, 44 are encoders, and J1 to J6 are rotation axes.

Claims

1. A robot sub-arm mechanism (11, 31, 41) is attached to a robot body (1) having a multi-axis arm (4-9) and an end effector (10) attached to its hand (9) for performing work, and is equipped with a sub-work tool (12) for performing auxiliary operations of the end effector, a moving arm mechanism (13) whose base end is supported by an intermediate arm (6) of the robot body, which holds the sub-work tool and moves it so as to follow the hand portion in response to a change in posture of the robot body; a posture maintaining mechanism (14, 32, 42) for maintaining a constant posture of the sub-work tool moved by the moving arm mechanism, the moving arm mechanism includes a support arm (15) having a base end attached to an intermediate arm (6) of the robot body and extending toward the hand end portion, and a swing arm (16) having a base end rotatably connected to a tip end portion of the support arm and having the sub work tool attached to its tip end, and the coupling portions (19) of these arms are located in the vicinity of the hand end portion, the posture maintaining mechanism includes a first parallel link mechanism (17) and a second parallel link mechanism (18), a base end link (17a) of the first parallel link mechanism is attached to the arm (4) on the base end side of the robot main body, a tip link (17b) opposite to the base end link of the first parallel link mechanism is connected to a base end link (18a) of the second parallel link mechanism, and a tip link (18b) opposite to the base end link of the second parallel link mechanism is connected to the swing arm; Robot sub-arm mechanism.

2. 2. A robot sub-arm mechanism as described in claim 1, wherein the robot main body is provided with a six-axis arm, the base end link of the first parallel link mechanism is attached to a one-axis arm (4) thereof, and the base end of the support arm is attached to a three-axis arm (6) thereof.

3. 2. The robot sub-arm mechanism according to claim 1, wherein two sets of the moving arm mechanism and the posture maintaining mechanism are provided symmetrically on both sides of the robot body, and the sub-work tool is attached in a double-supported state to the two swinging arms.

4. 2. A robot sub-arm mechanism as described in claim 1, wherein either or both of the first parallel link mechanism and the second parallel link mechanism are provided with a redundant intermediate link bar (33, 34) that connects the intermediate portions of the opposing base end link and tip end link to each other and is capable of adjusting its length.

5. 2. The robot sub-arm mechanism according to claim 1, wherein an encoder (43, 44) for detecting a posture is provided in at least one of the joints of the first parallel link mechanism or the second parallel link mechanism.

6. 2. The robot sub-arm mechanism according to claim 1, wherein the sub work tool is provided with an actuator that is operable independently of the robot body.

7. 2. A robot sub-arm mechanism according to claim 1, wherein the sub work tool is configured to have a movable part (12a) that is operated by an end effector of the robot main body.

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