A four-degree-of-freedom parallel robot mechanism capable of realizing SCARA-like motion

Abstract

The present invention discloses a four-degree-of-freedom parallel robot mechanism capable of realizing SCARA-like motion, comprising a fixed platform, a moving platform, and four branches evenly distributed around the moving platform; the branches comprise an active arm, an auxiliary active arm, a triangular joint, a U-shaped bracket, an upper connecting shaft, a telescopic parallel rod, and a lower connecting shaft. The auxiliary active arm is parallel to the active arm, one end of which is respectively rotatably connected to two places of the fixed platform, and the other end is respectively rotatably connected to the upper and lower parts of the triangular joint; the upper end of the U-shaped bracket is rotatably connected to the lower wall of the triangular joint, and the lower ends of the left and right side wing plates are rotatably connected to the upper connecting shaft; the upper end of the telescopic parallel rod is rotatably connected to the two ends of the upper connecting shaft, and the lower end is hinged to the two ends of the lower connecting shaft through a ball joint, and the lower connecting shaft is fixed on the moving platform. The branches of the present invention all contain two parallelogram structures, have greater rigidity and stability, and the ends can realize three translations and one rotation, and the movement is more flexible.

Description

Technical Field

[0001] The invention belongs to the field of industrial robots, and in particular relates to a four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion. Background Art

[0002] The parallel robot has a spatial multi-closed-loop structure, which can realize the motion output of the end effector through the coordinated action of multiple branches. Compared with the traditional serial mechanism, the parallel mechanism has the characteristics of high rigidity, large load-bearing capacity, high precision and compact structure.

[0003] The parallel robot with three-dimensional translation and one-dimensional rotation can also meet the needs of space object handling and other operations, and has been widely used in modern logistics, food and medicine, precision instrument installation and other fields that require fast and precise handling operations. The three-degree-of-freedom Delta mechanism can achieve three-dimensional high-speed translation in space, but with the development of the field of precision handling operations, the requirements for the placement of objects are gradually increasing, which cannot be achieved by relying solely on the pure translation Delta mechanism. Therefore, a placement process is required before the Delta can perform the grasping and releasing work. The four-degree-of-freedom parallel robot mechanism that can realize the SCARA motion form, namely "three translations and one rotation", came into being, but the existing SCARA mechanism motion form has problems such as small rotation ability, poor motion flexibility and low mechanism rigidity. Summary of the invention

[0004] The object of the present invention is to provide a parallel mechanism which is flexible in movement, has high rigidity and can realize SCARA movement (three translations and one rotation).

[0005] The technical solution to achieve the purpose of the present invention is:

[0006] A four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion of the present invention comprises a fixed platform, a moving platform, and a first branch chain, a second branch chain, a third branch chain, and a fourth branch chain arranged between the fixed platform and the moving platform, wherein the structures of the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain are exactly the same, and four frames are evenly distributed and fixed at 90-degree intervals in the circumferential direction of the fixed platform, and a driving motor and a reducer fixedly connected to the output shaft of the driving motor are fixed on each frame, and the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain are evenly distributed 90 degrees around the circumference of the fixed platform and the moving platform, and each branch chain comprises an active arm and an auxiliary active arm, and the upper end of the active arm is connected to the rotating shaft of the reducer through the first rotating shaft installed on the frame to form a first rotating connection with the moving platform, and the lower end is connected to the lower part of the triangular joint through the second rotating shaft connected to the triangular joint to form a second rotating connection; the upper end of the auxiliary active arm forms a third rotating connection with the third rotating shaft installed on the frame, and the lower end is connected to the third rotating shaft connected to the triangular joint The fourth rotation axis at the upper part of the joint is connected to form a fourth rotation connection. The lower wall of the triangular joint is arranged in the horizontal direction. The lower wall of the triangular joint is rotatably connected to the upper end of a connecting column arranged along the vertical direction of an axis. The active arm and the auxiliary active arm respectively constitute the two long sides of an upper parallelogram mechanism. The two short sides of the upper parallelogram mechanism are respectively formed by the connecting lines of the active arm and the auxiliary active arm with the hinge point of the triangular joint and by the connecting lines of the first rotation axis axis where the active arm is located and the third rotation axis axis where the auxiliary active arm is located. The two short sides of the upper parallelogram always form an angle of 60 degrees with the horizontal plane. The opening angle of the triangular joint is 60 degrees. Each branch chain includes a lower parallelogram mechanism composed of an upper connecting shaft, two remote frame parallel rods and a lower connecting shaft. The two remote frame parallel rods are the two long sides of the lower parallelogram mechanism. The lower connecting shaft is fixed to the moving platform by fastening bolts, and the two ends of the lower connecting shaft are connected to the lower ends of the two remote frame parallel rods by ball joints; the end actuator is fixed to the center of the moving platform;

[0007] The lower parallelogram mechanism is connected to the triangular joint through a rotating structure so that the lower parallelogram mechanism can rotate around the vertical axis of the connecting column. The upper ends of the two remote frame parallel rods are respectively connected to the upper connecting shaft through a first connecting structure. The upper connecting shaft is connected to the rotating structure through a second connecting structure. The rotating structure can rotate around the axis of the connecting column to form a first rotating pair. The rotating axes of the first rotating connection, the second rotating connection, the third rotating connection and the fourth rotating connection are orthogonal to the axis of the first rotating pair.

[0008] The advantages of the present invention are:

[0009] The three-parallel-rotation four-degree-of-freedom parallel robot of the present invention can realize SCARA motion and has high-speed motion characteristics. The lower parallelogram is added with a ball pair to make the motion more flexible. In addition, the mechanism has a compact structure, a clear motion mode, and a double parallelogram structure, with large rigidity and bearing capacity and stable motion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a structural schematic diagram of Example 1 of a four-degree-of-freedom parallel robot mechanism capable of realizing SCARA-like motion according to the present invention.

[0011] Figure 2 It is a schematic diagram of the structure of the moving platform in the mechanism of Example 1 of the present invention.

[0012] Figure 3 It is a schematic diagram of the structure of the branch chain in the mechanism of Example 1 of the present invention.

[0013] Figure 4 It is a schematic structural diagram of a moving platform according to another embodiment of the present invention.

[0014] Figure 5 This is a schematic structural diagram of Example 3 of a four-degree-of-freedom parallel robot mechanism capable of realizing SCARA-like motion according to the present invention.

[0015] Figure 6 for Figure 5 Schematic diagram of the structure of the branched chains in the structure shown. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0017] As shown in the accompanying drawings, a four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion includes a fixed platform 1, a moving platform 11, and a first branch chain, a second branch chain, a third branch chain, and a fourth branch chain arranged between the fixed platform and the moving platform. The structures of the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain are exactly the same, and four frames are evenly distributed and fixed at intervals of 90 degrees in the circumferential direction of the fixed platform 1, and a driving motor 3 and a reducer 2 fixedly connected to the output shaft of the driving motor 3 are fixed on each frame, and the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain are evenly distributed 90 degrees around the circumference of the fixed platform 1 and the moving platform 11. Each branch chain includes an active arm 5 and an auxiliary active arm 4. The upper end of the active arm 5 is connected to the rotating shaft of the reducer 2 through the first rotating shaft installed on the frame to form a first rotating connection with the moving platform, and the lower end is connected to the lower part of the triangular joint 6 through the second rotating shaft connected to the triangular joint 6 to form a second rotating connection; the upper end of the auxiliary active arm 4 is connected to the third rotating shaft installed on the frame to form a third rotating connection, and the lower end is connected to the fourth rotating shaft connected to the upper part of the triangular joint 6 to form a fourth rotating connection. The lower wall of the triangular joint 6 is arranged in the horizontal direction, and the lower wall of the triangular joint 6 is rotatably connected to the upper end of a connecting column arranged along the vertical direction. The active arm 5 and the auxiliary active arm 4 respectively constitute the two long sides of an upper parallelogram mechanism, and the two short sides of the upper parallelogram mechanism are respectively formed by the connecting lines of the active arm 5 and the auxiliary active arm 4 and the hinge points of the triangular joint 6, and by the connecting lines of the first rotating shaft axis where the active arm is located and the third rotating shaft axis where the auxiliary active arm is located.

[0018] The two short sides of the upper parallelogram always form an angle of 60 degrees with the horizontal plane, and the opening angle of the triangular joint 6 is 60 degrees.

[0019] Each branch chain includes a lower parallelogram mechanism consisting of an upper connecting shaft 8, two parallel rods of the remote frame 9 and a lower connecting shaft 10. The two parallel rods of the remote frame 9 are the two long sides of the lower parallelogram mechanism, the lower connecting shaft 10 is fixed to the moving platform by fastening bolts, and the two ends of the lower connecting shaft 10 are connected to the lower ends of the two parallel rods of the remote frame by ball joints; the moving platform 11 has two forms as shown in the attached drawings; the end effector 12 is fixed to the center of the moving platform 11, and the end effector 12 can adopt a suction cup device to realize suction and release actions.

[0020] The lower parallelogram mechanism is connected to the triangular joint 6 through a rotating structure so that the lower parallelogram mechanism can rotate around the vertical axis of the connecting column. The upper ends of the two remote frame parallel rods 9 are respectively connected to the upper connecting shaft 8 through a first connecting structure, and the upper connecting shaft 8 is connected to the rotating structure through a second connecting structure. The rotating structure can rotate around the axis of the connecting column to form a first rotating pair. The rotating axes of the first rotating connection, the second rotating connection, the third rotating connection and the fourth rotating connection are orthogonal to the axis of the first rotating pair.

[0021] As an embodiment of the present invention, Figure 1 As shown, the rotating structure 7 is a U-shaped bracket, the middle of the web of the U-shaped bracket is fixedly connected to the lower end of the connecting column, the second connecting structure is: the lower ends of the left and right side wing plates of the U-shaped bracket are connected to the upper connecting axis of the lower parallelogram through a rotating pair to form a second rotating pair, and the first connecting structure is: the two ends of the upper connecting axis are respectively rotatably connected to the upper ends of the two remote frame rods to form a third rotating pair, the rotation axis of the first rotating pair is orthogonal to the rotation axis of the second rotating pair, and the rotation axis of the second rotating pair is orthogonal to the rotation axis of the third rotating pair.

[0022] As another embodiment of the present invention, Figure 5-6 As shown, the rotating structure 7 is a rectangular body with a through hole in the middle, the lower end of the connecting column is fixedly connected to the middle of the top wall of the rectangular body, the second connecting structure is: the upper connecting shaft 8 passes through the through hole of the rectangular body and is fixedly connected to the rectangular body, and the first connecting structure is: the two ends of the upper connecting shaft are respectively connected to the upper ends of the two remote frame rods through ball joints.

[0023] The upper and lower parts between the two remote frame rods in the lower parallelogram are respectively connected with an upper connecting rod 13 and a lower connecting rod 14, wherein the two ends of the upper connecting rod 13 are respectively rotatably connected with the two remote frame rods to form a fourth rotation pair, and the two ends of the lower connecting rod 14 are respectively rotatably connected with the two remote frame rods to form a fifth rotation pair, and the fourth rotation pair and the fifth rotation pair are used to constrain the rotation of the two remote frame rods themselves, and the rotation axes of the fourth rotation pair and the fifth rotation pair are parallel to each other.

[0024] Combination Figure 2 , Figure 4 , Figure 2 The moving platform in the machine is an axisymmetric structure, and its clockwise and counterclockwise rotation capabilities are the same. Figure 4 The moving platform in the structure is a central symmetrical structure, and the four lower connecting shafts are also centrally symmetrical and fixed on the moving platform. Figure 2Compared with the moving platform in the figure, the lower connecting shaft 10 is fixed on the moving platform 11, and the end effector 12 is fixed at the center of the moving platform 11. When the assembly shown in the figure is adopted, that is, the moving platform is arranged symmetrically in the clockwise direction, the rotating ability of the moving platform in the clockwise direction is increased, which is more suitable for occasions where the objects are required to be placed in the clockwise direction. When the upside down is reversed, the end effector is still installed on the lower side, and the moving platform is arranged symmetrically in the counterclockwise direction, which increases the rotating ability of the moving platform in the clockwise direction, which is more suitable for occasions where the objects are required to be placed in the counterclockwise direction.

[0025] The above-described embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion, comprising a fixed platform, a moving platform, and a first branch chain, a second branch chain, a third branch chain, and a fourth branch chain arranged between the fixed platform and the moving platform, wherein the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain have the same structure, and four frames are evenly distributed and fixed at intervals of 90 degrees in the circumferential direction of the fixed platform, and a driving motor and a reducer fixedly connected to the output shaft of the driving motor are fixed on each frame, and the first branch chain, the second branch chain, the third branch chain, and the fourth branch chain are evenly distributed at intervals of 90 degrees around the circumference of the fixed platform and the moving platform, and are characterized in that: Each branch chain includes an active arm and an auxiliary active arm. The upper end of the active arm is connected to the shaft of the reducer through a first rotating shaft installed on the frame to form a first rotating connection with the moving platform, and the lower end is connected to the lower part of the triangular joint through a second rotating shaft connected to the triangular joint to form a second rotating connection; the upper end of the auxiliary active arm is connected to the third rotating shaft installed on the frame to form a third rotating connection, and the lower end is connected to the fourth rotating shaft connected to the upper part of the triangular joint to form a fourth rotating connection. The lower wall of the triangular joint is arranged in the horizontal direction, and the lower wall of the triangular joint is rotatably connected to the upper end of a connecting column arranged along the vertical direction by an axis. The active arm and the auxiliary active arm respectively constitute the two long sides of an upper parallelogram mechanism. The two short sides of the upper parallelogram mechanism are respectively formed by the connecting lines of the active arm and the auxiliary active arm and the hinge points of the triangular joint, and by the connecting lines of the first rotating shaft axis where the active arm is located and the third rotating shaft axis where the auxiliary active arm is located. The two short sides of the upper parallelogram always form an angle of 60 degrees with the horizontal plane, and the opening angle of the triangular joint is 60 degrees. Each branch chain includes a lower parallelogram mechanism composed of an upper connecting shaft, two remote frame parallel rods and a lower connecting shaft. The two remote frame parallel rods are the two long sides of the lower parallelogram mechanism. The lower connecting shaft is fixed to the moving platform by fastening bolts, and the two ends of the lower connecting shaft are connected to the lower ends of the two remote frame parallel rods by ball joints; the end actuator is fixed to the center of the moving platform; The lower parallelogram mechanism is connected to the triangular joint through a rotating structure so that the lower parallelogram mechanism can rotate around the vertical axis of the connecting column. The upper ends of the two remote frame parallel rods are respectively connected to the upper connecting shaft through a first connecting structure. The upper connecting shaft is connected to the rotating structure through a second connecting structure. The rotating structure can rotate around the axis of the connecting column to form a first rotating pair. The rotating axes of the first rotating connection, the second rotating connection, the third rotating connection and the fourth rotating connection are orthogonal to the axis of the first rotating pair.

2. The four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion according to claim 1, characterized in that: The rotating structure is a U-shaped bracket, and the middle of the web of the U-shaped bracket is fixedly connected to the lower end of the connecting column. The second connecting structure is: the lower ends of the left and right side wing plates of the U-shaped bracket are connected to the upper connecting axis of the lower parallelogram through a rotating pair to form a second rotating pair. The first connecting structure is: the two ends of the upper connecting axis are respectively rotatably connected to the upper ends of the two remote frame rods to form a third rotating pair. The rotation axis of the first rotating pair is orthogonal to the rotation axis of the second rotating pair, and the rotation axis of the second rotating pair is orthogonal to the rotation axis of the third rotating pair.

3. The four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion according to claim 1, characterized in that: The rotating structure is a rectangular body with a through hole in the middle, the lower end of the connecting column is fixedly connected to the middle of the top wall of the rectangular body, the second connecting structure is: the upper connecting shaft passes through the through hole of the rectangular body and is fixedly connected to the rectangular body, and the first connecting structure is: the two ends of the upper connecting shaft are respectively connected to the upper ends of the two remote frame rods through ball joints; The upper and lower parts between the two remote frame rods in the lower parallelogram are respectively connected with an upper connecting rod and a lower connecting rod, wherein the two ends of the upper connecting rod are respectively rotatably connected with the two remote frame rods to form a fourth rotating pair, and the two ends of the lower connecting rod are respectively rotatably connected with the two remote frame rods to form a fifth rotating pair, and the fourth rotating pair and the fifth rotating pair are used to constrain the rotation of the two remote frame rods themselves, and the rotation axes of the fourth rotating pair and the fifth rotating pair are parallel to each other.

4. The four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion according to any one of claims 1 to 3, characterized in that: The moving platform is an axisymmetric structure.

5. The four-degree-of-freedom parallel robot mechanism capable of realizing SCARA motion according to any one of claims 1 to 3, characterized in that: The moving platform is a centrosymmetrical structure, and the four lower connecting shafts are also centrosymmetrical and are all fixed on the moving platform.

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