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EP-4488546-B1 - PARALLEL LINK MECHANISM

EP4488546B1EP 4488546 B1EP4488546 B1EP 4488546B1EP-4488546-B1

Inventors

  • KANAOKA, KATSUYA
  • ZHANG, Ying Zi

Dates

Publication Date
20260513
Application Date
20230215

Claims (5)

  1. A parallel link mechanism (10A, 10B, 10C, 10D) comprising: a first movable body (20) and a second movable body (30) positioned on the same virtual line; a first parallel link portion (47) having a first base end and a first tip end and swingably connected at the first base end to the second movable body; a second parallel link portion (48) having a second base end and a second tip end and swingably connected at the second base end to the first tip end of the first parallel link portion; a first arm portion (45) having a third base end and a third tip end, rotatably connected at the third base end to the first movable body, and rotatably connected at the third tip end to the second parallel link portion at a first intermediate position between the second base end and the second tip end; a second arm portion (46a) having a fourth base end and a fourth tip end, rotatably connected at the fourth base end to the second movable body, and rotatably connected at the fourth tip end to the first arm portion at a second intermediate position (45a, 45b, 45c) between the third base end and the third tip end; and linear motion means (61, 71) capable of moving the first movable body and the second movable body individually along the virtual line, characterised in that the first parallel link portion (47) includes a first link member (40: rotatably connected at one end to the second movable body, a second link member (41) rotatably connected at one end to the second movable body, and a third link member (42) connected to other ends of the first and second link members, the second parallel link portion includes a fourth link member (44) and a fifth link member, with the fourth link member being rotatably connected at one end to the other end of the first link member and rotatably connected at another end to the end-effector (50), and the fifth link member being rotatably connected at one end to the other end of the second link member and rotatably connected at another end to the end-effector, the first link member, the second link member, and the first arm portion are parallel to one another, the fourth link member, the fifth link member, and the second arm portion are parallel to one another, the third link member, a line defined on the second movable body by connecting two rotation axes, and a line defined on the end-effector by connecting two rotation axes are parallel to one another, distancing between the fourth base end and the fourth tip end is equal to distancing between the third base end and the second intermediate position, and the fifth link member and the end-effector are connected at a point in the same plane as the second intermediate position, the plane being perpendicular to the virtual line.
  2. The parallel link mechanism according to claim 1, wherein, the linear motion means includes: a first ball screw shaft (61) and a second ball screw shaft (71) parallel to the virtual line; and a first rotation device (63) and a second rotation device (73) connected one-to-one with the first ball screw shaft and the second ball screw shaft, respectively, the first ball screw shaft is threaded in the first movable body but not in the second movable body, and the second ball screw shaft is threaded in the second movable body but not in the first movable body.
  3. The parallel link mechanism according to claim 2, further comprising: a base portion (90) placed on a floor surface; and a pillar portion (80) extending vertically upward from the base portion and including the linear motion means.
  4. The parallel link mechanism according to claim 3, wherein the base portion includes a third rotation device connected to the pillar portion.
  5. The parallel link mechanism according to claim 3 or 4, further comprising: a first constant-force spring exerting a constant vertically upward force on the first movable body regardless of displacement of the first movable body; and a second constant-force spring exerting a constant vertically upward force on the second movable body regardless of displacement of the second movable body.

Description

TECHNICAL FIELD The present invention relates to a parallel link mechanism that can be used as a work arm for performing various tasks. BACKGROUND ART One conventional link mechanism that can be used as a work arm is a link mechanism 100 shown in FIG. 7 (see Patent Document 1). The link mechanism 100, devised by the present applicant, includes movable bodies 110, 120, and 130 positioned on the same virtual line extending in the direction of gravity, first arm portions 111 rotatably connected at first base ends 111a to the movable body 110, second arm portions 121 rotatably connected at second base ends 121a to the movable body 120, third arm portions 131 rotatably connected at third base ends 131a to the movable body 130 and rotatably connected at third tip ends 131b to the second arm portion 121 between the second base ends 121a and second tip ends 121b, a work device 140 rotatably connected to both first tip ends 111b and the second tip ends 121b, and rotation devices 150, 151, and 152 capable of moving the movable bodies 110, 120, and 130 individually along the virtual line. Reference character W denotes a work object. In the link mechanism 100, the sum of forces generated by the three rotation devices 150, 151, and 152 acts as the force for lifting the work object W. In other words, the link mechanism 100 is capable of lifting the work object W by fully utilizing the forces generated by the three rotation devices 150, 151, and 152. On the other hand, the link mechanism 100 cannot adjust a horizontal (X-direction) reduction ratio independently of a gravitational-direction (Z-direction) reduction ratio. That is, the conventional link mechanism 100 realizes "coupled drive" but not "gravitationally decoupled reduction (GDR)". Note that coupled drive is explained in Non-Patent Document 1. Moreover, gravitationally decoupled reduction (GDR), defined for the first time herein by the present applicant, is a concept similar to "gravitationally decoupled actuation (GDA)" explained in Non-Patent Document 1. While GDA is a concept referring to decoupling drive actuators in gravitational and non-gravitational directions, GDR refers to decoupling (or individually designing) reduction ratios in gravitational and non-gravitational directions. This definition considers GDR a prerequisite for GDA. Moreover, the definition does not accommodate the realization of GDA simultaneously with the use of coupled drive in the same gravitational and non-gravitational directions, but the definition does not necessarily consider it contradictory to realize GDR simultaneously with the use of coupled drive in the same gravitational and non-gravitational directions. That is, both coupled drive and GDR can be realized at the same time. Patent documents 2 and 3 disclose various examples of parallel link mechanisms. Prior Art Documents Patent Document Patent Document 1: Japanese Laid-Open Patent Publication No. 2021-109253Patent document 2: JP S59 66594 U (YAMAHA CORPORATION) 4 May 1984Patent document 3: JP 2004 291171 A (SANYO MACHINE WORKS) 21 October 2004 Non-Patent Document Non-Patent Document 1: Shigeo Hirose, "Compact and Light-weight Design of Robot Mechanism", Journal of the Japan Society for Precise Engineering, The Japan Society for Precise Engineering, 1994, Vol. 60, No. 7, pp. 913-919 DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION The present invention has been achieved under the above circumstances, with a problem thereof being to provide a parallel link mechanism that realizes both coupled drive and gravitationally decoupled reduction. SOLUTION TO THE PROBLEMS To solve the above problem, a parallel link mechanism according to the present invention, as defined in the appended claim 1, includes a first movable body and a second movable body positioned on the same virtual line, a first parallel link portion having a first base end and a first tip end and swingably connected at the first base end to the second movable body, a second parallel link portion having a second base end and a second tip end and swingably connected at the second base end to the first tip end of the first parallel link portion, a first arm portion having a third base end and a third tip end, rotatably connected at the third base end to the first movable body, and rotatably connected at the third tip end to the second parallel link portion at a first intermediate position between the second base end and the second tip end, a second arm portion having a fourth base end and a fourth tip end, rotatably connected at the fourth base end to the second movable body, and rotatably connected at the fourth tip end to the first arm portion at a second intermediate position between the third base end and the third tip end, and linear motion means capable of moving the first movable body and the second movable body individually along the virtual line, and the second parallel link portion is swingably connected at the second tip end to an end-effector