A four-degree-of-freedom parallel mechanism based on wheel drive

Abstract

The present invention belongs to the technical field of parallel robots, and specifically relates to a four-degree-of-freedom parallel mechanism based on wheel drive, comprising a moving platform, parallelogram structures with offset angles are symmetrically arranged on the left and right sides of the upper surface of the moving platform, the moving platform is connected to a branched chain structure through the parallelogram structure with the offset angle, and an output platform is connected below the moving platform; the four-degree-of-freedom parallel mechanism provided by the present invention adopts wheel drive, so that the present invention can realize three-degree-of-freedom movement on a plane, so that the positioning space is similar to the environmental space, and the wheel drive enables the present invention to have the ability to work in complex environments, greatly improving the scope of application of the mechanism.

Description

Technical Field

[0001] The present invention belongs to the technical field of parallel robots, and in particular relates to a four-degree-of-freedom parallel mechanism based on wheel drive. Background Art

[0002] Traditional 3T1R parallel robots operate for sorting needs within a fixed range. Limited by the size of their workspace, they struggle to cope with the long-distance, fast-paced, simultaneous sorting and transportation requirements of multi-station collaborative operations in modern industrial automation. Currently, the common methods for long-distance grasping and transportation struggle to meet these requirements. The mobile robot + robotic arm operation method offers high flexibility and strong collaboration, but the robotic arm's workspace is limited, the overall structural rigidity is low, the load is small, and the center of gravity is unstable and prone to tipping during operation. The conveyor belt + parallel robot operation method offers high sorting efficiency, but the work position is fixed, the operation rhythm requires synchronization, the end load is small, and the degree of operational flexibility is low. The forklift-based operation method offers high load capacity and high reliability, but is slow and has poor environmental compatibility, making it difficult to meet flexible operational requirements. Therefore, there is an urgent need to liberate parallel robots from their fixed-position operation mode.

[0003] Among the various existing drive methods, wheeled drive can be used in a variety of complex environments, achieving more balanced and flexible operational requirements. Furthermore, wheeled structures are highly compatible with the working environment and offer high support rigidity. Especially when combined with symmetrical parallel robots, they can reduce the occurrence of special situations such as center of gravity shift and instability, and are easier to manufacture and maintain.

[0004] However, the current research on relevant theories and design methods based on the combination of wheeled structures and parallel robots is still incomplete: on the one hand, most existing parallel robots adopt multi-axis rocker mechanism design, suspended V-shaped assembly mode and servo motor drive mode, which makes it difficult to reasonably arrange the wheeled structure, and most parallel robots are not structurally compatible with the wheeled mechanism; on the other hand, the wheeled structure not only plays a transportation role, but also transmits motion to the parallel mechanism through the interaction between the wheels, which easily leads to coupling between the overall motion of the robot and the motion of the end moving platform. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a four-degree-of-freedom parallel mechanism based on wheel drive.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A four-degree-of-freedom parallel mechanism based on wheel drive includes a moving platform, parallelogram structures with offset angles are symmetrically arranged on the left and right sides of the upper surface of the moving platform, the moving platform is connected to a branched chain structure via the parallelogram structures with offset angles, and an output platform is connected below the moving platform;

[0008] The branch chain structure includes an upper connecting rod, which is fixedly connected to a parallelogram structure with an offset angle, an independent connecting rod is hinged on the front side of the upper connecting rod, and a third connecting rod is hinged in the middle of the upper connecting rod. The lower ends of the independent connecting rod and the third connecting rod are hinged to the housing of the second wheel hub motor, and a parallelogram connecting rod mechanism is formed between the upper connecting rod, the independent connecting rod, the third connecting rod and the second wheel hub motor. A harmonic reducer is fixedly mounted on the third connecting rod, a torque motor is fixedly mounted on the harmonic reducer, and the input end of the harmonic reducer is fixedly connected to the output shaft of the torque motor concentrically, and a fourth connecting rod is fixedly connected to the output shaft of the harmonic reducer. The output shaft of the wave reducer is arranged perpendicular to the fourth connecting rod, the lower end of the fourth connecting rod is hinged to the housing of the first hub motor, and the fifth connecting rod is also hinged on the housing of the first hub motor, the upper end of the fifth connecting rod is hinged to the lower end of the sixth connecting rod, and the upper end of the sixth connecting rod is hinged to the rear side of the upper end connecting rod. The lengths of the sixth, fifth and fourth connecting rods are the same as the distance from the torque motor to the upper end hinge point of the third connecting rod, and the line between the lower end hinge point of the fourth connecting rod and the lower end hinge point of the fifth connecting rod and the line between the upper end hinge point of the sixth connecting rod and the upper end hinge point of the third connecting rod are parallel and equal, and rollers are provided on the output shafts of the first hub motor and the second hub motor.

[0009] Furthermore, the parallelogram structure with an offset angle includes a rotating shaft rotatably connected to the moving platform, a lower end connecting member is fixedly connected to the upper end of the rotating shaft, a No. 1 connecting rod is hinged to the upper part of the lower end connecting member, a lower end fixing block is fixed to the lower part of the lower end connecting member, a No. 2 connecting rod is hinged to the lower end fixing block, the other end of the No. 2 connecting rod is hinged to the lower part of the upper end connecting member, the other end of the No. 1 connecting rod is hinged to the upper end fixing block, the upper end fixing block is fixedly arranged on the upper part of the upper end connecting member, and the upper end connecting member is fixedly connected to the upper end connecting rod.

[0010] Compared with the prior art, the present invention has the following advantages:

[0011] The four-degree-of-freedom parallel mechanism provided by the present invention adopts wheel drive, so that the present invention can realize three-degree-of-freedom movement on a plane, making the positioning space approximate to the environmental space, and the wheel drive enables the present invention to have the ability to work in complex environments, greatly improving the scope of application of the mechanism.

[0012] The present invention introduces a wheelbase control function in the branched chain structure. Through the synergistic effect of the torque motor and the harmonic reducer set on the third connecting rod, a braking torque opposite to the rotation direction of the rotating pair is output to restrict the relative rotation of the third connecting rod and the fourth connecting rod, thereby controlling the wheelbase between the front and rear rollers to remain unchanged, realizing partial decoupling of the roller movement and the output platform posture adjustment, so that the present invention has excellent end posture adjustment capability.

[0013] The present invention adopts a unique "4-2-1" structure, which drives the movement of two branch chain structures through four active mobile joints composed of two No. 1 hub motors and two No. 2 hub motors, thereby realizing three-dimensional translation and one-dimensional rotational movement of the moving platform. It not only has good movement stability, but also has a compact structure and high rotation flexibility.

[0014] The present invention adopts a parallelogram structure with an offset angle, which solves the rod interference problem that occurs in the conventional parallelogram mechanism during movement. The introduction of the offset angle can avoid the local singularity of the parallelogram and increase the posture adjustment space of the moving platform in the third direction.

[0015] The present invention has the advantages of compact structure, few moving components, low manufacturing cost, few singular configurations, positioning space similar to the environmental space, and large posture adjustment space. It can be widely used in removing explosives, picking underground crops and other similar tasks that require grasping actions in relatively complex ground environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention;

[0017] Figure 2 It is a structural schematic diagram of the dynamic platform of the present invention;

[0018] Figure 3 A schematic diagram of the turning motion of the present invention;

[0019] In the figure, there is a moving platform 1, a parallelogram structure 2 with an offset angle, a branched chain structure 3, an output platform 4, a planetary housing 101, a planetary gear 102, a sun gear 103, a central shaft 104, a rotating shaft 201, a lower end connecting piece 202, a No. 1 connecting rod 203, a lower end fixing block 204, a No. 2 connecting rod 205, an upper end connecting piece 206, an upper end fixing block 207, an upper end connecting rod 301, an independent connecting rod 302, a No. 3 connecting rod 303, a No. 2 hub motor 304, a torque motor 305, a harmonic reducer 306, a No. 4 connecting rod 307, a No. 1 hub motor 308, a No. 5 connecting rod 309, a No. 6 connecting rod 310, and a roller 311. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical solution of the present invention, the present invention is further described below through examples.

[0021] like Figures 1 to 3 As shown, a four-degree-of-freedom parallel mechanism based on wheel drive includes a moving platform 1, and parallelogram structures 2 with offset angles are symmetrically arranged on the left and right sides of the upper surface of the moving platform 1. The moving platform 1 is connected to the branch structure 3 through the parallelogram structure 2 with the offset angle, and an output platform 4 is connected below the moving platform 1.

[0022] The movable platform 1 includes a planetary housing 101, inside which two planetary gears 102 are arranged. The planetary gears 102 are fixedly connected to the lower end of the rotating shaft 201, and a sun gear 103 is meshed and connected between the two planetary gears 102. The planetary gears 102 and the sun gear 103 have the same number of teeth. The sun gear 103 is fixedly mounted on a central shaft 104, and the central shaft 104 is rotatably mounted on the planetary housing 101. The lower end of the central shaft 104 extends out of the planetary housing 101 and is fixedly connected to the output platform 4. The present invention introduces a planetary gear system into the movable platform 1, which can realize a double-angle output of the input rotation angle, thereby increasing the rotation range of the movable platform and greatly improving the posture adjustment space of the present invention.

[0023] The parallelogram structure 2 with an offset angle includes a rotating shaft 201 rotatably connected to the moving platform 1, a lower end connecting member 202 is fixedly connected to the upper end of the rotating shaft 201, a No. 1 connecting rod 203 is hinged to the upper part of the lower end connecting member 202, a lower end fixing block 204 is fixed to the lower part of the lower end connecting member 202, a No. 2 connecting rod 205 is hinged on the lower end fixing block 204, the other end of the No. 2 connecting rod 205 is hinged to the lower part of the upper end connecting member 206, the other end of the No. 1 connecting rod 203 is hinged to the upper end fixing block 207, the upper end fixing block 207 is fixedly set on the upper part of the upper end connecting member 206, and the upper end connecting member 206 is fixedly connected to the upper end connecting rod 301.

[0024] The branch chain structure 3 includes an upper end connecting rod 301, which is fixedly connected to the parallelogram structure 2 with an offset angle, and an independent connecting rod 302 is hinged on the front side of the upper end connecting rod 301, and a third connecting rod 303 is hinged in the middle of the upper end connecting rod 301, and the lower ends of the independent connecting rod 302 and the third connecting rod 303 are hinged to the housing of the second wheel hub motor 304, and a parallelogram connecting rod mechanism is formed between the upper end connecting rod 301, the independent connecting rod 302, the third connecting rod 303 and the second wheel hub motor 304, and a harmonic reducer 306 is fixedly installed on the third connecting rod 303, and a torque motor 305 is fixedly installed on the harmonic reducer 306, and the input end of the harmonic reducer 306 is fixedly connected to the output shaft of the torque motor 305, and a fourth connecting rod 307 is fixedly connected to the output shaft of the harmonic reducer 306. The output shaft of the reducer 306 and the fourth connecting rod 307 are arranged perpendicular to each other. The lower end of the fourth connecting rod 307 is hinged to the housing of the first wheel hub motor 308. The fifth connecting rod 309 is also hinged on the housing of the first wheel hub motor 308. The upper end of the fifth connecting rod 309 is hinged to the lower end of the sixth connecting rod 310. The upper end of the sixth connecting rod 310 is hinged to the rear side of the upper end connecting rod 301. The sixth connecting rod 310 and the fifth connecting rod 309 are hinged to each other. 09 and the length of the fourth connecting rod 307 are the same as the distance from the torque motor 305 to the upper end hinge point of the third connecting rod 303, and the line between the lower end hinge point of the fourth connecting rod 307 and the lower end hinge point of the fifth connecting rod 309 and the line between the upper end hinge point of the sixth connecting rod 310 and the upper end hinge point of the third connecting rod 303 are parallel and equal, and rollers 311 are provided on the output shafts of the first hub motor 308 and the second hub motor 304.

[0025] The foregoing shows and describes the principal features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and all variations that come within the meaning and range of equivalents of the claims are intended to be embraced therein.

[0026] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A four-degree-of-freedom parallel mechanism based on wheel drive, characterized by: The invention comprises a moving platform (1), parallelogram structures (2) with offset angles are symmetrically arranged on the left and right sides of the upper surface of the moving platform (1), the moving platform (1) is connected to the branch chain structure (3) via the parallelogram structure (2) with offset angles, and an output platform (4) is connected below the moving platform (1); The parallelogram structure (2) with an offset angle comprises a rotating shaft (201) rotatably connected to the moving platform (1), a lower end connecting member (202) is fixedly connected to the upper end of the rotating shaft (201), a No. 1 connecting rod (203) is hinged to the upper part of the lower end connecting member (202), a lower end fixing block (204) is fixed to the lower part of the lower end connecting member (202), a No. 2 connecting rod (205) is hinged to the lower end fixing block (204), the other end of the No. 2 connecting rod (205) is hinged to the lower part of the upper end connecting member (206), the other end of the No. 1 connecting rod (203) is hinged to the upper end fixing block (207), the upper end fixing block (207) is fixedly arranged on the upper part of the upper end connecting member (206), and the upper end connecting member (206) is fixedly connected to the upper end connecting rod (301); The branched chain structure (3) includes an upper connecting rod (301), the upper connecting rod (301) is fixedly connected to the parallelogram structure (2) with an offset angle, an independent connecting rod (302) is hinged on the front side of the upper connecting rod (301), a third connecting rod (303) is hinged on the middle part of the upper connecting rod (301), the lower ends of the independent connecting rod (302) and the third connecting rod (303) are hinged to the housing of the second wheel hub motor (304), and the upper connecting rod (301), the independent connecting rod (302) and the third connecting rod (303) are hinged to the housing of the second wheel hub motor (304). 02), a parallelogram connecting rod mechanism is formed between the third connecting rod (303) and the second wheel hub motor (304), a harmonic reducer (306) is fixedly mounted on the third connecting rod (303), a torque motor (305) is fixedly mounted on the harmonic reducer (306), and the input end of the harmonic reducer (306) is fixedly connected to the output shaft of the torque motor (305) concentrically, a fourth connecting rod (307) is fixedly connected to the output shaft of the harmonic reducer (306), the harmonic The output shaft of the wave reducer (306) and the fourth connecting rod (307) are arranged perpendicular to each other, the lower end of the fourth connecting rod (307) is hinged to the housing of the first wheel hub motor (308), and the fifth connecting rod (309) is hinged to the housing of the first wheel hub motor (308), the upper end of the fifth connecting rod (309) is hinged to the lower end of the sixth connecting rod (310), the upper end of the sixth connecting rod (310) is hinged to the rear side of the upper end connecting rod (301), and the sixth connecting rod (310) and the fifth connecting rod (309) are hinged to each other. The lengths of the connecting rod (309) and the fourth connecting rod (307) are the same as the distance from the torque motor (305) to the upper hinge point of the third connecting rod (303), and the line between the lower hinge point of the fourth connecting rod (307) and the lower hinge point of the fifth connecting rod (309) and the line between the upper hinge point of the sixth connecting rod (310) and the upper hinge point of the third connecting rod (303) are parallel and equal, and rollers (311) are provided on the output shafts of the first hub motor (308) and the second hub motor (304).

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