JP2011230241A - Parallel link robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such problems of a conventional technology that while a structure of fixing a motor flange face to a plate and coupling the plate with a robot body is often employed generally as a method of attaching a motor serving as a driving source of a robot and this structure is also common in a parallel link robot, a spindle of the motor moves due to influence of vibration or the like during high-speed motion and a relative position of an attached face and the motor shifts, resulting in a drop in positioning accuracy of the robot.SOLUTION: A method of attaching the motor of the parallel link robot employs a member for attaching opposite motors, which is made into a unified block structure. Thus, the conventional problem is solved, wherein center axes of at least two opposite motor spindles are aligned with each other, thereby alleviating the drop in positioning accuracy of the robot during high-speed motion. Such a method and an apparatus are disclosed.

Description

  The present invention relates to a mechanism of a robot mainly for industrial use. In particular, the present invention relates to a parallel link robot having a structure in which a fixed side plate for fixing a robot and a movable side plate to which an action member such as an end effector is attached are connected by a plurality of arms.

  The parallel link robot is composed of a fixed plate for fixing the robot, a movable plate to which an action member such as an end effector is attached, and an arm and a rod for connecting them. The arm is attached to the fixed plate so as to pivot about a unique axis in a unique plane. Both ends of the rod are coupled by a bearing that freely rotates in the space such as a ball joint, and the position and posture of each arm and rod can be changed in the space while being coupled and restrained by a movable plate. By controlling the arm rotation position with a drive source such as a motor, the position and posture of the movable plate can be controlled.

  As a parallel link robot, a method of controlling a movable plate surface with six degrees of freedom by independently controlling a six-axis motor has been proposed (see, for example, Patent Document 1).

  FIG. 5 is a schematic perspective view of the parallel link robot of Patent Document 1. As shown in FIG. In FIG. 5, the parallel link robot 1 connects the fixed plate 2 and the movable plate 3 with an arm 4 and a rod 7, and controls the position and posture of the arm 4 and the rod 7 to automatically move the movable plate 3. Control the behavior.

  The arm 4 is connected to the main shaft of the motor 5, and the motor 5 often employs a structure in which the flange surface is fixed to the plate 6 and the plate 6 is coupled to the fixed plate 2. The parallel link robot shown in Patent Document 1 also has this configuration.

JP-A-6-270077

  However, the conventional configuration has a problem that the positioning accuracy of the parallel link robot is lowered due to the main shaft of the motor being shaken by the influence of vibration or the like during high-speed operation, and the relative position of the mounting surface and the motor being displaced.

  The present invention solves the above-described conventional problems and makes at least the central axes of two motor spindles facing each other coincide with each other to reduce a decrease in positioning accuracy of the parallel link robot during high-speed operation.

  In order to achieve the above object, a parallel link robot of the present invention is a parallel link robot in which a movable plate and a fixed plate are connected by three sets of six arms, each driving one set of two arms. The motor shafts of the two motors are respectively held by blocks via bearings, and the motor shafts are configured to be the same shaft.

  As described above, according to the present invention, the influence of the decrease in the positioning accuracy of the parallel link robot, which occurs when the motor spindle is shaken due to the influence of vibration or the like during high-speed operation and the relative position of the mounting surface and the motor shifts, is affected. It is possible to reduce and match at least the central axes of the two motor spindles facing each other to ensure the positioning accuracy of the robot during high-speed operation.

1 is a schematic perspective view of a parallel link robot according to a first embodiment of the present invention. The schematic perspective view of the block structure which attaches the motor of this Embodiment 1 which opposes (A) Cross-sectional view of the block when the arm interval of the first embodiment is wide, (b) Cross-sectional view of the block when the arm interval of the first embodiment is narrow (A) Rotation operation model diagram of movable plate when arm interval of Embodiment 1 is wide, (b) Rotation operation model diagram of movable plate when arm interval of Embodiment 1 is narrow Schematic perspective view of parallel link robot of Patent Document 1

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, and description thereof is omitted as appropriate.

(Embodiment 1)
FIG. 1 shows a schematic perspective view of the parallel link robot according to the first embodiment of the present invention. The parallel link robot 11 connects the fixed plate 2 and the movable plate 3 with the arm 4 and the rod 7 via the block 12, and controls the position and posture of the arm 4 and the rod 7 to control the movable plate 3. Control automatic operation. The block 12 is fixed to the fixing plate 2 with two or more bolts or the like.

  The arm 4 is connected to the main shaft of the motor 19, and the motor 19 often adopts a structure in which the flange surface 13 is coupled to the fixed plate 2 via a plate or the like. Six degrees of freedom (movable axes) are necessary for the movable plate 3 to be able to freely define the position and posture in space. The parallel link robot 11 according to the first embodiment has a structure in which the position and posture of the movable plate 3 are freely set by using six sets of the arm 4 and the motor 5 and independently controlling their rotational positions.

  The arm 4 is attached so as to turn in a unique plane around one axis. Both ends of the rod 7 are connected by a bearing that freely rotates in the space such as a ball joint, and each arm 4 and the rod 7 are coupled and restrained by the movable plate 3 while changing the position and posture in the space. Can do. By controlling the rotational position of the arm 4 with a drive source such as a motor 19, the position and posture of the movable plate 3 can be controlled.

  It is preferable in terms of control calculation that the six arms 4 are arranged such that two parallel sets are set as one set, and three sets are arranged in 120 degrees equally in the circumferential direction.

  However, since these arms 4 need to be able to operate independently, the motor shafts 19a of a set of two motors 19 cannot be coupled to each other. Further, since the tips of these six sets of arm 4 and rod 7 are coupled to the same movable plate 3, the distance from the center of the motor shaft 19a to the movable plate 3 via the arm 4 and rod 7 is equal to each other. Otherwise, there may be a problem that the position and posture of the movable plate 3 cannot be controlled to the target position. Therefore, it is very important to match the centers of the motor shafts 19a of the two motors 19 in one set.

  FIG. 2 is a schematic configuration diagram of a block structure for attaching the opposing motor 19. Reference numeral 12 denotes a block main body, and reference numeral 13 denotes a flange surface to which the motor 19 is attached. The opposing flange surfaces 13 ensure parallelism by machining. Reference numeral 14 denotes a screw hole for attaching the motor 19. In order to show the internal shape of the block 12, sectional views of the block 12 in the section 15 are shown in FIGS. 3 (a) and 3 (b) are symmetrical diagrams, the reference numerals are given only to the configuration on one side.

  3A is a cross-sectional view of the block 12 when the arm interval is wide, and FIG. 3B is a cross-sectional view of the block 12 when the arm interval is narrow.

  Near the center of the through-hole 16 machined in the block 12, a bearing 17 is provided for holding the end portions of the motor shafts 19a of the two opposing motors 19, respectively. A gap is provided between the two bearings 17 by a spacer 18 so that the ends of the motor shaft 19a of the motor 19 do not interfere with each other.

  The motor shaft 19a of the motor 19 is inserted into the block 12 from the left and right sides, received by the bearing 17, and the motor 19 is fixed to the block 12 with bolts or the like using the screw holes 14.

  Since the two bearings 17 are positioned in the radial direction with reference to the same through hole, the centers of the two bearings 17 coincide. Along with this, by inserting the opposite end of the motor shaft 19 a into the bearing 17, the center of the motor shaft 19 a coincides with the vicinity of the central block.

  Moreover, since the motor 19 is fixed through the screw hole 14, it is pressed against the flange surface 13, and the parallelism of both the motor 19 is ensured. Therefore, when the opposing motors 5 are fixed, their central axes are on the same straight line, and it is possible to mount them without axial misalignment at both axial centers.

  Reference numeral 4 denotes an arm of the parallel link robot 11 attached to the motor shaft 19a. One arm 4 is attached to each of the two motors 19, and the rotational position can be controlled independently.

  21 is a notch of the block 12 provided for the arm 4 to rotate. The mounting position of the arm 4 can be moved and adjusted in the width direction of the notch 21 (the core direction of the motor shaft 5a). The larger the width L1 of the lateral cutout 21 in FIGS. 3A and 3B, the greater the degree of freedom in the mounting position of the arm 4. The mounting position of the arm 4 is basically mounted at a position equidistant from the center of the block 12 and has a symmetrical configuration. The distance L2 between the arms 4 affects the driving torque and rotational speed of the movable plate 3 attached via the rod 7.

  FIGS. 4A and 4B are rotational operation model diagrams of the movable plate 3 for explaining that the distance between the arms 4 affects the driving torque and the rotational speed of the movable plate 3.

  FIG. 4A shows a case where the arm interval and the rod interval are wide, and is a schematic diagram showing the movable plate 3 and a set of two rods 7 coupled thereto. Similarly, FIG. 4B shows a case where the arm interval and the rod interval are narrow. These correspond to FIG. 3 (a) and FIG. 3 (b), respectively.

  4 (a) and 4 (b), when a reverse force is applied to the rod 7 as indicated by arrows 22a and 22b in the drawing, the movable plate 3 receives a rotational force.

  Here, the interval between the rods 7 is the same as the above-described arm interval L2. As shown in FIG. 4A, when the distance L2 between the rods 7 is large, the torque for rotating the movable plate 3 increases, and the rotation angle becomes relatively small.

  On the contrary, when the distance L2 between the rods 7 is small as shown in FIG. 4B, the torque for rotating the movable plate 3 becomes small, and the rotation angle becomes relatively large.

  Here, as the width L1 of the notch 21 of the block 12 shown in FIGS. 3A and 3B increases, the degree of freedom increases in the attachment position of the arm 4, that is, the interval L2 of the arm 4. For example, if the block 12 in which the distance L2 between the arms 4 is variable from a minimum of 40 mm to a maximum of 120 mm is used, the rotational torque and the rotational angle of the movable plate 3 are set to optimum trade-off conditions in a range of three times each. Is possible.

  As described above, according to the present invention, the motor 19 is attached to the block 12, and at the same time, the parallelism and the axis centers of the two opposing motor shafts 19a can be matched. Therefore, the relative position of the flange surface 13 and the motor 19 does not shift, and the problem that the positioning accuracy of the parallel link robot 11 during high-speed operation is reduced can be realized with easy and high-precision mounting.

  Further, since there is a degree of freedom in the mounting interval of the arms 4, it is possible to optimize conflicting conditions such as the rotational torque and the rotational angle of the movable plate 3. Moreover, since the two motors 19 can be attached in one block, the member cost can be reduced.

  INDUSTRIAL APPLICABILITY The present invention can ensure the positioning accuracy of a robot during high-speed operation in a parallel link robot, and is useful for such a parallel link robot.

DESCRIPTION OF SYMBOLS 1, 11 Parallel link robot 2 Fixed plate 3 Movable plate 4 Arm 5, 19 Motor 7 Rod 12 Block 13 Flange surface 14 Screw hole 15 Cross section 16 Through hole 17 Bearing 18 Spacer 19a Motor shaft 21 Notch

Claims (4)

A parallel link robot in which a movable plate and a fixed plate are connected by three sets of six arms,
A parallel link robot characterized in that the motor shafts of two motors that respectively drive a set of two arms are respectively held by blocks via bearings, and the motor shafts are the same axis. 2. The parallel link robot according to claim 1, wherein spacers are provided between bearings respectively holding motor shafts of motors for driving a set of two arms. 3. The parallel according to claim 1, wherein the arms are respectively disposed in two notches of the block, and a tip of the motor shaft is disposed in the vicinity of the block located between the two notches. Link robot. The parallel link robot according to claim 3, wherein a distance between the pair of two arms is variable by moving the arm in two notches of the block.

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