JP2005066723A - Parallel robot with four degrees of freedom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a parallel robot with four degrees of freedom achieving parallel displacement with two degrees of freedom and turning movement with two degrees of freedom. <P>SOLUTION: The parallel robot with four degrees of freedom is composed of a base 1; four sets of linear motion actuators 4a, 4b, 5a, 5b secured to the base; a link 2 for parallel displacement with two degrees of freedom; a link 3 for turning movement with two degrees of freedom; two sets of ball joint mechanisms 6, 7; and a working tool 8. The working tool 8 is constituted to be able to make parallel displacement with two degrees of freedom and turning movement with two degrees of freedom. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to a working robot that employs a parallel mechanism in which a plurality of actuators are arranged. INDUSTRIAL APPLICABILITY The present invention can be used for an operation robot or the like used for operations such as surgery support or transfer, processing, and assembly at a medical site.

  Conventionally, when drilling a work object, for example, as shown in FIG. 7, an operator 301 holds a work tool 303 such as an electric drill with respect to the work object 302 in both hands. The position and direction are determined, and drilling is performed while pushing the working tool 303 in the tool axis direction.

  If the work object is large and fixed on the table of the processing machine and drilling work is difficult, or if the work object that cannot be moved is labor-saving and automated, these work should be performed. A robot for work to be performed on behalf of humans is required. At least the freedom of movement required for the work robot is a total of 4 degrees of freedom: 2 degrees of freedom for parallel movement to align the position of the work tool, and 2 degrees of freedom for rotational movement to align the direction of tilt, etc. A degree of movement is required. Further, when drilling, a parallel movement with one degree of freedom is required to push the work tool. There are a number of robot structures that enable this three-degree-of-freedom parallel movement and two-degree-of-freedom swivel movement, but a parallel mechanism that allows multiple actuators to be placed rearward is suitable for downsizing the structure near the work tool. ing.

  In particular, in order to make the work robot hold the work tool in both hands and determine the position and direction of the work tool by parallel movement and turning movement, the parallel movement of 2 degrees of freedom and 2 degrees of freedom A four-degree-of-freedom parallel mechanism that realizes a swivel movement is most suitable. Furthermore, when the feed is given after the position and direction of the working tool are determined as in drilling or the like, it is necessary to add a parallel movement of one degree of freedom to this parallel mechanism.

  The parallel mechanism generally has 6 degrees of freedom with 6 actuators. However, since a parallel movement with 2 degrees of freedom and a swivel movement with 2 degrees of freedom are sufficient for a working robot, a parallel link structure with 6 degrees of freedom is substituted. In some cases, the extra actuator and link mechanism not only complicate the structure, but also increase the probability of failure.

In many cases, work robots have four degrees of freedom using four actuators, considering that it is sufficient to have four degrees of freedom for the convenience of parallel movement in the vertical and horizontal directions and rotational movement in the horizontal plane. A parallel mechanism is proposed in Patent Document 1. Further, Patent Document 2 proposes a drive device that can perform angular displacement around each of the X-axis and Y-axis in the XYZ orthogonal triaxial coordinate system and movement displacement in the Z-axis direction.
JP 2001-88072 A JP-A-8-11081

  However, the four-degree-of-freedom parallel robot of Patent Document 1 enables parallel movement of three degrees of freedom and swivel movement of one degree of freedom, and does not allow arbitrary swivel movement, but directs the work tool in any direction. I can't. Further, the 4-degree-of-freedom parallel robot of Patent Document 2 is capable of parallel movement of 1 degree of freedom and rotational movement of 3 degrees of freedom, and cannot be translated to an arbitrary position. It cannot be positioned at any position. According to the applicant's investigation, there is no example of a 4-DOF parallel mechanism structure that realizes 2-DOF parallel movement and 2-DOF pivoting movement.

  Therefore, an object of the present invention is to provide a 4-DOF parallel robot that realizes 2-DOF parallel movement and 2-DOF turning movement.

  In order to solve the above problems, the present invention provides a four-degree-of-freedom parallel robot that includes a base, four linear actuators fixed to the base, and two linear actuators having one end among the linear actuators. An arm rod that engages with the actuator rod so as to be capable of one-degree-of-freedom rotation, a ball joint mechanism that rotatably engages with the other end of the arm rod, and one of the other two linear motion actuators. An arm rod that engages with an actuator rod of a linear motion actuator so as to be capable of pivoting motion with three degrees of freedom, a ball joint mechanism that rotatably engages with the other end of the arm rod, and these two ball joint mechanisms It is composed of a working tool that is supported by a swivel by means of a parallel movement with two degrees of freedom and a swiveling movement with two degrees of freedom. And it can be so.

  Furthermore, in order to solve the above-described problems, the present invention provides a base, four linear actuators fixed to the base, and one free actuator rod of one of the linear actuators and one end of the linear actuator. An arm rod engaged so as to be capable of rotating at a predetermined degree, a ball joint mechanism rotatably engaged with the other end of the arm rod, and an actuator of one of the other two linear motion actuators with one end being the linear motion actuator An arm rod that engages with the rod so as to allow a three-degree-of-freedom swivel movement, a ball joint mechanism that rotatably engages with the other end of the arm rod, and a pivot joint that is supported by these two ball joint mechanisms And a work unit having a built-in drive unit capable of parallel movement with one degree of freedom. Tsu and so bets can three degrees of freedom translation and two degrees of freedom pivoting move.

  In the present invention, it is possible to determine the position and direction of the work tool by two-degree-of-freedom parallel movement and two-degree-of-freedom swivel movement. The human motion of determining the position and direction of the work tool is replaced with the work robot, and in order to save work and automate, the most appropriate parallel link structure compared to the conventional 4-degree-of-freedom parallel robot. is there.

  Further, compared to the conventional 6-degree-of-freedom parallel link structure, there is no need for an extra actuator and link mechanism, and there is an effect that the structure is simple and the movement control program for each actuator is simplified. In addition, there is an effect that the probability of failure is low and the manufacturing cost is low as compared to the parallel link structure of 6 degrees of freedom.

  Furthermore, the present invention replaces the above-described work tool with a work unit incorporating a spindle unit driving device capable of moving forward and backward, so that a person has the work tool in both hands, and the position of the work tool and After determining the direction, there is an effect that it is possible to realize the robotization that is close to the movement of the person by pushing the work tool with both arms as a whole.

  The best mode for carrying out the four-degree-of-freedom parallel robot of the present invention will be described in the following examples.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view illustrating a configuration of a four-degree-of-freedom parallel robot according to the first embodiment. FIG. 2 is a cross-sectional view of the 4-degree-of-freedom parallel robot in the first embodiment. As shown in FIG. 1, the four-degree-of-freedom parallel robot in the first embodiment includes a base 1, four sets of linear motion actuators 4 a, 4 b, 5 a, 5 b fixed to the base 1, and two degrees of freedom described later. The parallel movement link 2, the two-degree-of-freedom turning movement link 3, two sets of ball joint mechanisms 6 and 7, and a work tool 8 are included.

  The centers of the four sets of linear actuators 4 a, 4 b, 5 a, 5 b are fixed to the base 1 so as to be rectangular vertices. When the direction in which the cutting tool 10 attached to the end portion of the work tool 8 via the spindle unit 9 is defined as the front, the linear motion actuators 4a and 4b are disposed forward, and the linear motion actuators 5a and 5b are disposed rearward. Yes.

  As shown in FIG. 2, the two linear actuators 4a and 4b arranged in the front are housings 11a and 11b, servo motors 12a and 12b attached to the ends of the housings 11a and 11b, and a servo motor 12a, respectively. , 12b and ball screws 13a, 13b and actuator rods 14a, 14b that are connected to the ball screws 13a, 13b and move forward and backward within the housings 11a, 11b. In this embodiment, a ball screw is used as the linear actuator, but a rack and pinion, a fluid cylinder, or the like can also be used.

  At the ends of the actuator rods 14a and 14b, circular convex joint pieces 15a and 15b are provided. The circular concave joint pieces 17a and 17b and pins 18 provided on the arm rods 16a and 16b, which will be described later, are free. Engagement is possible so as to allow a degree of swivel movement. A part of the pin 19 fixed to the housings 11a and 11b is fitted into a groove provided in the actuator rods 14a and 14b so as to be freely movable, thereby preventing the actuator rods 14a and 14b from rotating with respect to the housings 11a and 11b.

  The end portions of the arm rods 16a and 16b are provided with the aforementioned circular concave joint pieces 17a and 17b, and the other end having a flange shape is rotatably engaged with the ball joint outer ring 21 via the bearing 20. Yes. As the actuator rods 14a and 14b move forward and backward independently, the center of the ball joint outer ring 21 moves in a plane parallel to the XY plane. That is, the actuator rods 14a and 14b, the arm rods 16a and 16b, and the ball joint outer ring 21 constitute the two-degree-of-freedom parallel movement link 2.

  As shown in FIG. 2, the linear motion actuators 5a and 5b arranged on the rear side include housings 22a and 22b, servomotors 23a and 23b attached to the ends of the housings 22a and 22b, and servomotors 23a and 23b. It consists of ball screws 24a and 24b to be driven and actuator rods 25a and 25b that are connected to the ball screws 24a and 24b so as to move forward and backward inside the housings 22a and 22b.

  Spherical convex ball joint pieces 26a and 26b are provided at the ends of the actuator rods 25a and 25b, and the spherical concave ball joint pieces 28a and 28b provided on the arm rods 27a and 27b, which will be described later, rotate with three degrees of freedom. Engaged to allow movement. A part of the pin 19 fixed to the housings 22a and 22b is inserted into a groove provided in the actuator rods 25a and 25b so as to be freely movable, thereby preventing the actuator rods 25a and 25b from rotating with respect to the housings 22a and 22b.

  The end portions of the arm rods 27a and 27b are provided with the concave ball joint pieces 28a and 28b described above, and the other end having a flange shape is rotatably engaged with the ball joint outer ring 29 via the bearing 20. .

  The concave spherical portion provided on the inner diameter of the front ball joint outer ring 21 and the convex spherical portion provided on the outer diameter of the ball joint inner ring 30 are engaged with each other so as to be able to perform a three-degree-of-freedom turning motion. A ball joint mechanism 6 is configured. Similarly, the concave spherical portion provided on the inner diameter of the ball joint outer ring 29 and the convex spherical portion provided on the outer diameter of the ball joint inner ring 31 are engaged with each other so as to be able to perform a three-degree-of-freedom turning motion. A joint mechanism 7 is configured.

  The ball joint inner rings 30 and 31 are disposed at positions where the mounting interval is equal to the interval between the two linear motion actuators 4a and 4b disposed at the front and the linear motion actuators 5a and 5b disposed at the rear. The tool 8 is supported. The work tool 8 includes anti-rotation mechanisms 32 and 33 between the work tool 8 and the arm rod 16a in order to prevent turning around the axis.

  The actuator rods 25a and 25b move forward and backward independently, so that the work tool 8 is supported at the center of the ball joint mechanism 6 disposed forward via the arm rods 27a and 27b and the rear ball joint mechanism 7. 2 turns with 2 degrees of freedom. That is, the actuator rods 25a and 25b and the arm rods 27a and 27b constitute the two-degree-of-freedom turning movement link 3.

  The operation of the first embodiment of the four-degree-of-freedom parallel robot provided with the two-degree-of-freedom parallel movement link 2 and the two-degree-of-freedom turning movement link 3 will be described below. By giving a predetermined operation command to a control device (not shown), the servo motors 12a, 12b, 23a, and 23b of the four sets of linear motion actuators 4a, 4b, 5a, and 5b are individually driven to be actuator rods 14a, 14b, 25a, and 25b are moved forward and backward independently. Then, the working tool 8 can be controlled with four degrees of freedom via the two-degree-of-freedom parallel movement link 2 and the two-degree-of-freedom turning movement link 3. That is, the center position of the ball joint mechanism 6 in the XY plane is determined by the two-degree-of-freedom parallel movement link 2 disposed in the front, and the work tool 8 is formed by the two-degree-of-freedom turning movement link 3 disposed in the rear. Determine the posture. As a result, the working tool 8 can be moved to a desired position and posture by synchronously driving the servo motors 12a, 12b, 23a, and 23b by a predetermined amount as shown in FIG. After the work tool 8 is moved to a desired position and posture, the work object (not shown) is subjected to predetermined processing by the spindle unit 9 and the cutting tool 10 attached to the work tool 8.

  Further, as shown in FIG. 4, the guide unit 102 is provided on the base 101, and the base 101 is driven by the servo motor 104 along the slide base 103. Along with the determination of the posture, the range of use of the 4-DOF parallel robot can be expanded.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 5 shows a five-degree-of-freedom robot in which a work unit 202 having a built-in spindle unit 207 capable of advancing / retreating, that is, one-degree-of-freedom parallel movement is substituted for the work tool 8 in the four-degree-of-freedom parallel robot of the first embodiment. FIG. 6 is a perspective view showing a configuration of Example 2. FIG. 6 is a cross-sectional view showing the configuration of the second embodiment.

  As shown in the sectional view of FIG. 6, the work unit 202 is connected to the unit case 203, the servo motor 204 fixed to the unit case 203, the ball screw 205 driven by the servo motor 204, and the ball screw 205. The actuator rod 206 moves forward and backward inside the unit case 203, the spindle unit 207 attached to the tip of the actuator rod 206, and the blade 208 held by the spindle unit 207. A part of the pin 209 fixed to the unit case 203 is inserted into a groove provided in the actuator rod 206 so as to be freely movable, thereby preventing the actuator rod 206 from rotating with respect to the unit case 203.

  The operation of the second embodiment will be described below. By giving a predetermined operation command to a control device (not shown), the work unit 202 replaced with the work tool 8 is moved to a desired position and posture as described in the operation description of the first embodiment. . Next, an operation command is given to the servo motor 204, and the working unit 202 is moved to a desired position and posture by rotating the blade 208, and then a work such as drilling is sent to the work object (not shown). Necessary processing can be performed.

1 is a perspective view showing a configuration of a 4-degree-of-freedom parallel robot in Embodiment 1. FIG. 1 is a cross-sectional view of a 4-degree-of-freedom parallel robot in Embodiment 1. FIG. It is a perspective view which shows the state which moved the working tool to the desired position and attitude | position. It is a perspective view which shows providing a guide part in a base and driving a base along a slide base with a servomotor. FIG. 6 is a perspective view illustrating a configuration of a five-degree-of-freedom robot according to a second embodiment. 6 is a cross-sectional view of a five-degree-of-freedom robot in Embodiment 2. FIG. It is a perspective view which shows the conventional Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base 2 2 degrees of freedom parallel movement link 3 2 degrees of freedom turning movement link 4a Linear motion actuator 5a Linear motion actuator 6 Ball joint mechanism 7 Ball joint mechanism 8 Working tool 10 Cutting tool 12a Servo motor 14a Actuator rod 16a Arm rod 202 Work unit 204 Servo motor 207 Spindle unit 208 Cutting tool

Claims (2)

  A base, four linear actuators fixed to the base, and an arm whose one end engages with the actuator rods of two of the linear actuators so as to be capable of one-degree-of-freedom turning motion A rod, a ball joint mechanism that is rotatably engaged with the other end of the arm rod, and one end of the other direct acting actuator with the actuator rod of the other two direct acting actuators so that a three-degree-of-freedom swivel motion is possible. An arm rod that is engaged, a ball joint mechanism that is rotatably engaged with the other end of the arm rod, and a work tool that is rotatably supported by these two ball joint mechanisms. A four-degree-of-freedom parallel robot characterized in that a tool can move in parallel with two degrees of freedom and turn with two degrees of freedom. The base, the four linear motion actuators fixed to the base, and the arm having one end engaged with the actuator rods of two of the linear motion actuators so as to be able to perform one degree of freedom of rotation. A rod, a ball joint mechanism that rotatably engages with the other end of the arm rod, and an actuator rod of one of the other two linear motion actuators at one end so that a three-degree-of-freedom swivel motion is possible. An arm rod to be engaged, a ball joint mechanism that is rotatably engaged with the other end of the arm rod, and a drive device that is pivotally supported by these two ball joint mechanisms and capable of parallel movement with one degree of freedom. It is composed of a built-in work unit, and the work unit can be translated in 3 degrees of freedom and turned in 2 degrees of freedom. 5 degree-of-freedom robot which is characterized.

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