JP4696384B2 - Parallel link robot - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a parallel type industrial robot used as a six-degree-of-freedom motion mechanism for position and posture control.
[0002]
[Prior art]
Conventionally, an electric cylinder has been widely used as an actuator for performing a reciprocating linear motion. The electric cylinder has no fear of the hydraulic oil flowing out, and if a servo motor is used, it can be used for precise positioning control and attitude control, so it is useful as an actuator for a so-called parallel link robot.
As a conventional example of an electric cylinder, there is one described in Japanese Patent Application Laid-Open No. 2000-46140, which was previously developed and patented by the present applicant. This is an electric cylinder that can minimize the ratio of the total length to the operation stroke, and has the center of gravity height as low as possible when arranged in the vertical direction. By using this, a parallel link robot with a large operation range is used. Is obtained.
FIG. 5 is a side sectional view of the electric cylinder 51 showing the embodiment. In the figure, reference numeral 52 denotes a cylindrical casing, and the cylindrical casing 52 is obtained by connecting an upper casing 52a and a long lower casing 52b in a vertically stacked manner. A ball nut 53 is rotatably attached to the upper casing 52a. A ball spline 54 is fixed to the upper end of the upper casing 52a. Reference numeral 55 denotes a ball screw / spline, which is a long shaft formed by superimposing a screw groove and a spline groove.
The ball screw / spline 55 is disposed inside the cylindrical casing 52 concentrically with the long axis of the cylindrical casing 52, screwed into the ball nut 53, fitted into the ball spline 54, and outside the upper casing 52a. Protruding. Since the ball screw / spline 55 is fitted to the ball spline 54, the ball screw / spline 55 can freely advance and retreat in the length direction, but its rotation is restricted.
Accordingly, the ball screw / spline 55 freely moves forward and backward from the upper casing 52 a by the rotation of the ball nut 53. Reference numeral 56 denotes a movable side joint, which is attached to an end of the ball screw / spline 55 that protrudes from the upper casing 52 a and connects the operation target (not shown) of the electric cylinder 51 and the ball screw / spline 55.
Reference numeral 57 denotes a housing fixed to the lower casing 52 b, and 58 denotes a motor arranged in parallel with the ball screw / spline 55. The motor 57 is fixed to the housing 57, and its output shaft projects into the housing 57.
A hollow shaft 59 is connected to the ball nut 53 via a spacer 510, and passes through the ball screw / spline 55 through the hollow portion and through the lower casing 52b to the inside of the housing 57. That is, the ball screw / spline 55, the hollow shaft 59, and the lower casing 52b are arranged concentrically in order from the inside. Reference numeral 511 denotes a first pulley which is connected to the hollow shaft 59 and is rotatably supported by the housing 57 via a bearing. The first pulley 511 is hollow, and the ball screw / spline 55 extends through the hollow portion of the first pulley 511 to the bottom of the housing 57. 512 is a second pulley connected to the output shaft of the motor 58;
A timing belt 513 is bridged between the first pulley 511 and the power of the motor 58 is transmitted to the ball screw / spline 55. Reference numeral 514 denotes a fixed joint provided protruding from the lower portion of the housing 57, and is a joint that couples the operation target of the electric cylinder 51 and the housing 57.
Thus, the electric cylinder 51 has the ball nut 53 disposed near the upper end of the cylindrical casing 52 so that the ball screw / spline 55 can be moved back and forth between the ball nut 53 and the housing 57. The operation stroke of 55 can be taken large.
Further, since the ball nut 53 and the hollow shaft 59 are connected and the power of the motor 58 is transmitted to the hollow shaft 59 at the lower end of the hollow shaft 59, a heavy object such as the motor 58 is transferred to the lower part of the electric cylinder 51. The center of gravity can be lowered.
[0003]
FIG. 6 is a side view showing an example in which the electric cylinder 51 of FIG. 5 is applied to a parallel link robot. In the figure, 61 is a parallel link robot. The parallel link robot 61 includes a base plate 62, three electric cylinders 63, 64, 65, a restraint link 66, a movable table 67, and a wrist 68. The electric cylinders 63, 64, 65 are the electric cylinder 51 of FIG. 5, one end of which is connected to the base plate 62 via universal joints 63a, 64a, 65a, and the other end is a movable table via universal joints 63b, 64b, 65b. 67 (the electric cylinder 64 overlaps the back side of the electric cylinder 63 and is not visible in FIG. 6).
The restraining link 66 is a telescopic link that restrains the movable table 67 from being twisted with respect to the base plate 62. One end of the restraining link 66 is connected to the base plate 62 via a universal joint 66 a and the other end is fixed to the movable table 67. Yes. The wrist 68 has three axis rotational degrees of freedom (1) swiveling around the first axis perpendicular to the movable table 67, (2) raising and lowering around the second axis perpendicular to the first axis, and (3) end effector mounting. (Rotation of the flange 68a) and is fixed to the movable table 67.
The parallel link robot 61 assembled in this manner freely moves the movable table 67 up and down, left and right, and back and forth by freely extending and retracting the electric cylinders 63, 64, and 65 in accordance with a command from the control panel. By rotating the three axes 68, the end effector attached to the flange 68a can take an arbitrary posture at an arbitrary position.
According to this, since the electric cylinders 63, 64, and 65 have a short overall length and a long operation stroke, the operation range of the movable table 67 can be increased.
Moreover, since the electric cylinders 63, 64, 65 have heavy objects such as motors arranged below, the center of gravity is low and the work when swinging around the universal joints 63a, 64a, 65a is small. Can be driven with small power.
[0004]
[Problems to be solved by the invention]
However, the parallel link robot 61 shown in FIG. 6 has three degrees of freedom and is inconvenient for precise control.
Further, other parallel link robot technologies other than those shown in FIG. 6 have a six-degree-of-freedom motion mechanism. However, they require six links, and a ball pair or universal for connecting the links. A large number of parts are required, such as a joint is required, or the number of arms is six, and a universal joint constituting the arm and a ball pair for connecting the arm and the movable plate are necessary. There was a problem of becoming.
Furthermore, since the base and the movable plate are connected by six arms, a space for installing six pairs is required, which causes a problem that the base and the movable plate become large. It was.
Therefore, an object of the present invention is to provide a parallel link robot having a six-degree-of-freedom motion mechanism in a compact manner with a reduced number of parts.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the parallel link robot according to claim 1 includes a base, a movable plate for attaching an end effector, and two ends each connected to the base and the movable plate. A parallel link robot composed of three pairs of arms each composed of a link , wherein one base end of the arm is composed of two rotary pairs whose rotation axes are not parallel to the base. The other base end is connected to the movable plate by a ball pair, and the link constituting the pair of arms has a linear motion pair and is extendable and retractable. In the parallel link robot in which one of the kinematic pair and the control actuator for the linear motion pair are mounted, in addition to the three sets of arms, three sets of spring dampers are connected to the base with two-degree-of-freedom rotating pairs. Linking Is characterized in that it is connected with the movable plate and the ball even number.
The invention of the parallel link robot according to claim 2 is a set comprising a base, a movable plate for attaching an end effector, and two links each having one end connected to the base and the movable plate. A parallel link robot composed of three pairs of arms, wherein one base end of the arm is a two-degree-of-freedom rotational pair composed of two rotational pairs whose rotation axis is not parallel to the base. The other base end is connected to the movable plate by a ball pair, and the link constituting the pair of arms has a linear motion pair and can be expanded and contracted, and one of the rotary pair and the linear motion In a parallel link robot equipped with a drive actuator that can be controlled by a pair, in addition to the three sets of arms, one of a pair of spring dampers is connected to the center of the base by a two-degree-of-freedom rotational pair, The other is Characterized in that it is connected in the center and the sphere kinematic pair of the movable plate.
Parallel link robot.
According to a third aspect of the present invention, in the parallel link robot according to the first or second aspect , the two-degree-of-freedom rotation pair is configured by a universal joint whose rotation axes are orthogonal to each other.
According to a fourth aspect of the present invention, in the parallel link robot according to the first or second aspect , the two-degree-of-freedom rotation pair is configured by providing a distance between the rotation axes at the link so that the rotation axes are not orthogonal to each other. And
According to a fifth aspect of the present invention, in the parallel link robot according to the first or second aspect , a controllable drive actuator is attached to a rotary pair directly connected to the base of the two-degree-of-freedom rotary pair. It is characterized by.
According to a sixth aspect of the present invention, in the parallel link robot according to the first or second aspect , of the two-degree-of-freedom rotational pair, the rotational pair directly connected to the base is free to rotate and is controlled to the other rotational pair. A possible drive actuator is mounted.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
First, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a perspective view showing a parallel link robot according to a first embodiment.
In FIG. 1, 1 is a parallel link robot according to the first embodiment, 11 is a base, 12 is a movable plate, 13 is an arm, 13L1 is an upper link, 13L2 is a lower link, 14U is a two-degree-of-freedom rotating pair, 15K is a ball pair, and 16G is a linear motion pair.
As shown in FIG. 1, the parallel link robot 1 includes a base 11, a movable plate 12, and three sets of arms 13. The three sets of arms 13 are equally spaced by 120 °.
The arm 13 includes an upper link 13L1, a lower link 13L2, and a linear motion pair 16G interposed between the upper link 13L1 and the lower link 13L2.
The configuration of the arm 13 itself can be realized by using the electric cylinder 51 of FIG. Then, one base end of the arm 13 (the lower end of the lower link 13L2) is connected to the base 11 with a two-degree-of-freedom rotational pair 14U (see FIGS. 3 and 4) described later, and the other base end ( The upper end of the upper link 13L1 is connected to the movable plate 12 by a ball pair 15K. The link connected to the movable plate 12 is free to extend and contract by a linear motion pair 16G, and an actuator that can be controlled by each of the linear motion pair 16G and one of the two-degree-of-freedom rotational pairs 14U. Wearing.
[0007]
3 and 4 are diagrams showing two specific examples of the two-degree-of-freedom rotation pair used in FIG.
FIG. 3 shows two examples in which the two-degree-of-freedom rotation pair 14U is configured by a universal joint in which two rotation shafts 3 and 4 are orthogonal to each other.
In FIG. 3, 11 is a base, 13L1 is an upper link, 13L2 is a lower link 13, 16G is a linear motion pair, and the upper link 13L1, the lower link 13L2, and a linear motion pair 16G constitute an arm 13. Reference numerals 3 and 4 denote orthogonal rotating pairs, which form a two-degree-of-freedom rotating pair 14U.
In FIG. 3A, a driving actuator is mounted on the rotary pair 3, and in FIG. 3B, a driving actuator is mounted on the rotary pair 4.
[0008]
FIG. 7 is a perspective view showing an example of the entire arm portion to which the two-degree-of-freedom rotating pair 14U of FIG. In the figure, 3 is a shaft of one rotary pair, 31 is a motor provided in the direction of the shaft 3, and 32 is a motor shaft. The motor 31 is installed on the base 11 at an interval. Reference numeral 4 denotes the axis of the other rotating pair, and the axes 3 and 4 are perpendicular to each other. Reference numeral 41 denotes a motor provided in the direction of the shaft 4, and reference numeral 42 denotes a motor shaft. The motor 41 is installed at the center of a U-shaped member fixed to the motor shaft 32 and penetrates the motor shaft 42 so as to be rotatable.
On the other hand, another U-shaped member 44 is fixed to the shaft 42, and the electric cylinder 7 of FIG. 5 is provided on the U-shaped member 44. 13M is a motor, 57 is a housing, 51 is an upper casing, and 52 is a lower casing. The upper casing 51 and the lower casing 52 constitute a cylindrical casing 53, and the upper link 13 </ b> L <b> 1 is provided from the cylindrical casing 53 so as to be freely raised and lowered. Since these operations have been described in detail with reference to FIG. 5, they are omitted here.
With the above configuration, the upper link 13L1 connected to the movable plate to which the end effector is attached can be rotated in the A direction around the shaft 3 by the motor 31, and can be rotated in the B direction around the shaft 4 by the motor 41. It is possible to move in the C direction on the shaft 8 at 13M.
The above is a specific example of FIG. 3A, but the same applies to FIG. 3B, and the disclosure of the specific example is omitted.
[0009]
FIG. 4 shows an example in which a two-degree-of-freedom rotating pair 14U is connected and configured by a link 21 so that the rotating shafts 5 and 6 of the two rotating pairs are not orthogonal.
In FIG. 4, 11 is a base, 13 is an arm, 16G is a linear pair, and the upper link 13L1, the lower link 13L2, and the linear pair 16G constitute an arm 13. 3 and 4 are rotating pairs that are not orthogonal to each other, 21 is a link that connects the rotating shafts 5 and 6 of the two rotating pairs so as not to be orthogonal, and the rotating pairs 3 and 4 and the link 21 form a two-degree-of-freedom rotating pair 14U. It is composed.
In FIG. 4A, a driving actuator is attached to the rotary pair 5, and in FIG. 4B, a driving actuator is attached to the rotary pair 6.
With the above configuration, by giving an operation command from the control device (not shown) to each of the driving actuators mounted on each pair, the movable plate is positioned by swinging and expanding / contracting the rotational pair and the linear pair. The attitude can be controlled.
[0010]
FIG. 2 is a perspective view showing a parallel link robot according to a second embodiment of the present invention. In the parallel link robot of the second embodiment, a base and a movable plate are connected by a spring damper for assisting a driving force in the vertical direction. As a result, the load on the motor 13M (FIG. 7) and the like can be reduced, which contributes to downsizing.
2A shows an example using three sets of spring dampers 21, and FIG. 2B shows an example using one set of spring dampers 21 ′.
First, in FIG. 2A, 2 is a parallel link robot according to the second embodiment, 11 is a base, 12 is a movable plate, 13 is an arm, 13L1 is an upper link, 13L2 is a lower link, and 14U is two A rotational pair of degrees of freedom, 15K is a ball pair, and 16G is a linear motion pair. Reference numeral 21 denotes a spring damper.
2A, the parallel link robot 2 includes a base 11, a movable plate 12, and three sets of arms 13. The three sets of arms 13 are equally spaced by 120 °. The arm 13 includes an upper link 13L1, a lower link 13L2, and a linear motion pair 16G interposed between the upper link 13L1 and the lower link 13L2.
As described above, the parallel link robot 2 is composed of three pairs of ball pairs on the base 11 and the movable plate 12 and is extremely compact. Therefore, it is possible to connect the three sets of spring dampers 21 in excess. It becomes possible. The spring damper 21 is connected to the base 11 by a universal joint 24U, and is connected to the movable plate 12 by a ball pair 25K. Since the driving force in the vertical direction is assisted by the spring damper 21, the load applied to the motor 13M (FIG. 7) and the like can be reduced, and the overall size can be reduced.
FIG. 2B shows a set of spring dampers 21 ′ having a driving force larger than that of the spring damper 21 shown in FIG. 2A, arranged between the center of the base 11 and the center of the movable plate 12. Is. And the connection with the center of the base 11 is performed by the universal joint 24U ′, and the connection with the center of the movable plate 12 is performed by the ball pair 25K ′. Other configurations are the same as those in FIG.
As described above, according to the parallel link robot 2 ′ of FIG. 2B, since it is composed of a pair of spring dampers 21 ′, the entire apparatus is operated while performing the same operation as the parallel link robot 2 of FIG. Can be further simplified.
[0011]
【The invention's effect】
As described above, according to the parallel link robot 1, 2, 2 ′ of the present invention, since it can be constituted by the three sets of arms 13, the universal joint 14U, and the ball pair 15K, the number of even pairs can be reduced. There is an effect that the base 11 and the movable plate 12 can be made small and compact.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a parallel link robot according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a parallel link robot according to a second embodiment of the present invention.
FIG. 3 is an enlarged view showing one specific example of a two-degree-of-freedom rotation pair of the parallel link robot shown in FIG. 1;
4 is an enlarged view showing another specific example of the two-degree-of-freedom rotation pair of the parallel link robot shown in FIG. 1. FIG.
FIG. 5 is a side sectional view of a known electric cylinder developed by the present applicant.
FIG. 6 is a side view of a known parallel link robot made using three electric cylinders of FIG.
7 is a perspective view showing the entire arm portion to which the two-degree-of-freedom rotating pair 14U of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Parallel link robot 11 based on 1st Embodiment of this invention Base 12 Movable plate 13 Arm 13L1 Upper link 13L2 Lower link 14U, 24U, 24U 'Two-degree-of-freedom rotation pair 15K, 25K, 25k' Ball pair 16G Moving pair 2, 2 'Parallel link robot 21, 21' according to the second embodiment of the present invention Spring damper 3, 4, 5, 6 Rotating pair 7 Electric cylinder 31, 41, 13M Motor

Claims (6)

A parallel structure composed of a base, a movable plate for attaching an end effector, and a pair of arms each composed of two links each having one end coupled to the base and the movable plate. In the link robot , one base end of the arm is connected to the base by a two-degree-of-freedom rotary pair configured by two rotary pairs whose rotation axes are not parallel, and the other base end is the movable plate The link constituting the pair of arms is connected to each other by a ball pair and is extendable and retractable, and a controllable drive actuator is mounted on one of the rotary pair and the linear pair. In parallel link robot ,
A parallel link robot characterized in that , in addition to the three sets of arms, three sets of spring dampers are connected to the base by two-degree-of-freedom rotary pairs, and are connected to the movable plate by ball pairs . A parallel structure composed of a base, a movable plate for attaching an end effector, and a pair of arms each composed of two links each having one end coupled to the base and the movable plate. In the link robot, one base end of the arm is connected to the base by a two-degree-of-freedom rotary pair configured by two rotary pairs whose rotation axes are not parallel, and the other base end is the movable plate The link constituting the pair of arms is connected to each other by a ball pair and is extendable and retractable, and a controllable drive actuator is mounted on one of the rotary pair and the linear pair. In parallel link robot,
In addition to the three sets of arms, one of the set of spring dampers is connected to the center of the base by a two-degree-of-freedom rotating pair, and the other is connected to the center of the movable plate by a ball pair. Parallel link robot. The parallel link robot according to claim 1 or 2 , wherein the two-degree-of-freedom rotation pair is configured by a universal joint whose rotation axes are orthogonal to each other . Claim 1 or 2 parallel robot according at link such that the rotation axis is not perpendicular to to have a distance between the rotation axis, characterized by being configured the two degree of freedom turning pair. 3. The parallel link robot according to claim 1 , wherein a controllable drive actuator is attached to a rotation pair directly connected to the base among the two-degree-of-freedom rotation pairs . Of the two degree of freedom turning pair, and freely rotating the turning pair being connected said direct a base, according to claim 1 or 2, wherein the wearing the other controllable drive actuator to turning pair of Parallel link robot.

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