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Title:
A THREE FINGER ROBOTIC GRIPPER DESIGN WITH SPHERICAL MECHANISM
Document Type and Number:
WIPO Patent Application WO/2021/107900
Kind Code:
A1
Abstract:
The invention relates to robotic grippers, which are generally used in robotic systems to grasp objects while moving from one location to another. Its feature is that three spherical four-link mechanisms placed symmetrically on a spherical plane perform the grasping process by means of the special position of the fixed joints (5-6) and the special dimensions of the link (2-3-4). These mechanisms are like fingers for the robotic gripper. The invention allows the coupler link (4) to move towards the poles in a longitudinal orbit on a spherical plane, by means of the servo motor (11) connected to the control of an electronic processor, moving the driving link (2) to the object (10-12 -13) to be grasped by three fingers performs the grasping process thanks to the application of force from three points (force-closed holding). If the dimensions of the object (10-12-13) are close to but smaller than the diameter of the spherical plane where the coupler link (3) of the spherical mechanism moves, it can be grasped by the enveloping the object (10-12-13) (form-closed). This symmetrical three-spherical four-link mechanism can be easily connected to a robotic arm thanks to the palm (1) and the connection element (9).

Inventors:
SAGLAM HACI (TR)
ACAR OSMAN (TR)
SAKA ZIYA (TR)
Application Number:
PCT/TR2020/051155
Publication Date:
June 03, 2021
Filing Date:
November 24, 2020
Export Citation:
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Assignee:
SELCUK UNIV (TR)
International Classes:
B25J15/10
Foreign References:
CN104908056A2015-09-16
CN105563513A2016-05-11
CN105940335A2016-09-14
Attorney, Agent or Firm:
AKKAS, Ahmet (TR)
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Claims:
CLAIMS

1. A three finger robotic gripper design with spherical mechanism characterized by comprising; a controller to give commands, a servo motor (11) to drive a driving link (2) and a coupler link (4) on a longitudinal trajectory on a spherical plane with the command of the controller to grasp cylindrical hollow (10), cubic object (12) or spherical object (13) under effects of three forces or restricting motion by the closed form made of three fingers and palm (1), wherein the driving link (2) and a driven link (3) are designed in the same radius, the coupler link (4) is designed in a bigger radius.

Description:
A THREE FINGER ROBOTIC GRIPPER DESIGN WITH SPHERICAL MECHANISM TECHNICAL AREA

The invention relates to robotic grippers used in robotic systems to grasp objects generally to move from one location to another. Its feature is that the three four-link spherical mechanisms, which make up the robotic finger, are placed symmetrically on a spherical plane, thanks to the special position of the fixed joints and the special dimensions of the links, enabling movement in a longitudinal orbit on a spherical plane, compacting or encircling the objects.

BACKGROUND OF THE INVENTION

Robotic grippers usually consist of two or three fingers. The fingers perform the grasping process with planar motion. In order to increase the grip capability of the gripper, the fingers surround the object by means of joints and restrict the movement of the object grasped by contact from several different points. However, since these joints generally increase the degree of freedom of the gasping process, these joints require a separate drive element. The products of ROBOTIQ and SCHUNK companies, which are the most well-known in the gripper sector, are generally grasp by planar motion. Therefore, capability of grippers are required to be improved and degree of freedom is need to be decreased.

TECHNICAL PROBLEMS WHICH THE INVENTION AIMS TO SOLVE

An object can be grasped under two or three forces in order to achieve static equilibrium or to restrict its movement by enveloping it around. In the process of grasping with a planar movement that meets these conditions, extra drive is required as the degree of freedom increases in the finger joints, while a movement in the spherical plane can ensure that the object is grasped in equilibrium or to envelop around under two or three forces without requiring an extra drive. Therefore, optimum four-link spherical mechanism, which can provide a longitudinal movement in the spherical plane is designed. This mechanism is placed symmetrically around a sphere and a three-finger gripper is designed. Thus, with independent drives each mechanism can keep an object in balance under three forces, as well as grasp by enveloping it around. Objects with irregular geometry can also be grasped by independently controlling each finger of the gripper. However, the grasping capacity of this gripper can be increased only by the proper design of the fingertip, without changing the size of the mechanism, by using fingertips with larger radii.

LIST OF THE DRAWINGS

Figure 1 : 3-dimension isometric view of the gripper, Figure 2: Gripper grasping a cylindrical hollow, Figure 3: Gripper grasping a cubic object,

Figure 4: Gripper grasping a spherical object,

Brief Description of the Reference Numerations

1. Palm

2. Driving link

3. Driven link

4. Coupler link

5. Fixed joint

6. Fixed joint

7. Mobile joint

8. Mobile joint

9. Connection screws of robot arm and gripper

10. Cylindrical hollow

11. Driving element servo motor

12. Cubic object

13. Spherical object

DESCRIPTION OF THE INVENTION

The invention provides grasping cylindrical hollow (10), cubic object (12) or spherical object (13) under effects of three forces or restricting motion by the closed form made of three fingers and palm (1 ) thanks to by commending from a controller to servo motor (11 ) driving the driving link (2) which moves the coupler link (4) on a longitudinal trajectory on spherical plane. There is no inconvenience changing the radius of the spherical surface where the motion occurs unless the angles between axes kept. Therefore, as the driving link (2) and the driven link (3) were designed in the same radius, the coupler link (4) was designed in a bigger radius. THE APPLICATION FORMAT

The invention can be used in several production lines of industrial applications by assembling to robotic arm by the help of connection screws of robot arm and gripper (9). Work of the gripper fingers is provided by a controller. The gripper can supply facility in grasping objects with regular or irregular geometry unless it does not exceed the diameter of the gripper. The dimensions of the invention are determined specifically for longitudinal motion without three fingers hitting each other. Thus, it must be produced in the special dimensions which are required to be protected by patent.