Four-degree-of-freedom mechanical arm structure

Abstract

The utility model discloses a four-degree-of-freedom mechanical arm structure which is installed on a rotating shaft of a humanoid robot and comprises a forward flexion / backward extension module, an abduction / adduction module, an inward / outward rotation module, an elbow joint module and a small arm module, and the mass center of each module is located on the rotating shaft. The forward bending / backward stretching module is used for achieving the abduction / adduction freedom degree of the mechanical arm, the abduction / adduction module is used for achieving the abduction / adduction freedom degree of the mechanical arm, the inward / outward rotation module is used for achieving the inward / outward rotation freedom degree of the mechanical arm, and the elbow joint module is used for achieving the elbow joint freedom degree of the mechanical arm. The rotation freedom degree of the humanoid robot upper limb has low rotational inertia, the motor load is greatly reduced, the humanoid robot upper limb has high stability under high dynamic impact, and the anthropomorphism and overall coordination of the humanoid robot upper limb are greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of intelligent robots, and in particular to a four-degree-of-freedom mechanical arm structure. Background Art

[0002] With the development of robotics and artificial intelligence, robots are increasingly being used to assist or replace humans in certain tasks. Unlike traditional industrial robots and collaborative robots, which are limited to specific scenarios, humanoid robots can operate like humans. Their anthropomorphic movements are suitable for a wide range of fields, including medical rehabilitation, service, industrial, specialized operations, and military, enabling them to perform tasks in a wide range of scenarios.

[0003] A search revealed a Chinese utility model patent, publication number CN207087915U, which discloses a four-degree-of-freedom robotic arm. The patent comprises a shoulder base, a first boom servo motor, a waist servo motor, a waist reducer, a base, a second boom servo motor, an boom guide rail, a first boom push rod, a first lead screw, a first boom connecting rod, an end effector connector, a forearm, a wrist servo motor, a second boom connecting rod, an boom connecting plate, a first boom slider, a second boom push rod, a second lead screw, and a second boom slider. The shoulder base is fixedly connected to the housing of the waist reducer. The first and second boom servo motors, as well as one end of the boom guide rail, are each fixedly connected to the shoulder base. One end of the first lead screw is connected to the second boom servo motor, and the other end is rotatably connected to the boom connecting plate. The second lead screw is connected to the first boom servo motor, and the other end is rotatably connected to the boom connecting plate. This robotic arm improves its load-bearing capacity, reduces inertia during operation, and ensures stable operation.

[0004] After searching, the Chinese utility model patent with publication number CN218170428U discloses a four-degree-of-freedom robotic arm control structure, including: a mechanical claw for grasping materials; a second rotating mechanism connected to the mechanical claw, the second rotating mechanism is used to drive the mechanical claw to perform circular motion with a first axis as the rotation axis; a moving mechanism connected to the second rotating mechanism, the moving mechanism is used to drive the mechanical claw to move horizontally and vertically on the displacement plane; the first rotating mechanism includes a frame and a first rotating power device, the first rotating power device is connected to the frame, and the first rotating power device is connected to the moving mechanism to drive the moving mechanism to perform circular motion with a second axis as the rotation axis. The four-degree-of-freedom robotic arm control structure has two rotating axes and two vertical linear extensions. The range of motion of the mechanical claw is a hollow cylinder, which has relatively intuitive spatial positioning and high conveying efficiency.

[0005] However, the robotic arm structure proposed in the above patent generally has a high moment of inertia. With long-term use, the load on the motor tends to gradually increase, which not only wastes electricity but also makes the motor easily damaged due to long-term load. Moreover, the existing robotic arm structure has a low degree of anthropomorphism during use, poor overall coordination, and is prone to misoperation.

[0006] Therefore, based on existing research technology, the utility model provides a four-degree-of-freedom robotic arm structure for a humanoid robot. Each rotational degree of freedom has a low moment of inertia, which greatly reduces the motor load and has high stability under high dynamic impact, greatly improving the anthropomorphism and overall coordination of the humanoid robot's upper limbs. Utility Model Content

[0007] In order to solve the above problems, the utility model provides a four-degree-of-freedom robotic arm structure with anthropomorphic degrees of freedom, low moment of inertia, high stability, and modular assembly.

[0008] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0009] A four-degree-of-freedom robotic arm structure is mounted on the rotation axis of a humanoid robot. It is characterized by comprising a flexion / extension module, an abduction / adduction module, an internal / external rotation module, an elbow joint module, and a forearm module. The center of mass of each module is on the rotation axis.

[0010] The flexion / extension module includes a flexion / extension joint module, and the abduction / adduction module is connected to the flexion / extension joint module;

[0011] The abduction / adduction module includes an abduction / adduction joint front fixator, an abduction / adduction joint module, an abduction / adduction joint coupling block, an abduction / adduction joint rear fixator, a first stepped flange bearing, and a bearing end cover. The abduction / adduction joint coupling block is fixedly connected to the flexion / extension joint module by bolts. The abduction / adduction joint front fixator and the abduction / adduction joint rear fixator are respectively provided with limiting steps on the outside. The abduction / adduction joint coupling block is located in the limiting steps and is respectively fixedly connected to the abduction / adduction joint front fixator and the abduction / adduction joint rear fixator by bolts. The abduction / adduction joint module is located between the abduction / adduction joint front fixator and the abduction / adduction joint rear fixator. A flange bearing limit is provided on the outside of the abduction / adduction joint rear fixator. The inner ring of the first stepped flange bearing is fixedly connected to the flange bearing limit. At the same time, the bearing end cover presses the outer ring of the first stepped flange bearing and is fixedly connected to the abduction / adduction joint rear fixator.

[0012] The internal / external rotation module includes a coupling block, a coupling block fixing frame, an internal / external rotation joint module upper fixing frame, an internal / external rotation joint module, and an internal / external rotation joint module lower fixing frame, the internal / external rotation joint module is installed on the internal / external rotation joint module lower fixing frame, the internal / external rotation joint module upper fixing frame is sleeved on the internal / external rotation joint module and fixed to the internal / external rotation joint module lower fixing frame, the coupling block is fixedly connected to the abduction / adduction joint module by bolts, the coupling block is provided with a limiting flange, the abduction / adduction joint front fixing frame is provided with a first limiting groove, the limiting flange is installed in the first limiting groove to achieve anthropomorphic limiting of the abduction / adduction degree of freedom within the limit, the coupling block and the coupling block fixing frame are fixedly connected by bolts, the coupling block and the coupling block fixing frame are respectively provided with a second limiting groove, and are transitionally matched with the internal / external rotation joint module upper fixing frame, and are fixedly connected by bolts;

[0013] The elbow joint module includes an outer fixing frame of an elbow joint module, an elbow joint module, an elbow joint coupling block, an elbow joint bearing end cover, a second stepped flange bearing, and an inner fixing frame of the elbow joint module. The outer fixing frame of the elbow joint module and the inner fixing frame of the elbow joint module are respectively provided with a third limiting groove, which is connected to the pin provided on the elbow joint coupling block and is fixedly connected by bolts. The other end of the elbow joint coupling block is provided with a limiting cover, and works together with the lower fixing frame of the internal / external rotation joint module to achieve anthropomorphic limiting of the elbow joint module. The outer ring of the second stepped flange bearing has an interference fit with the inner fixing frame of the elbow joint module, and its inner ring has an interference fit with the protrusion of the elbow joint bearing end cover. One side of the elbow joint bearing end cover presses the second stepped flange bearing;

[0014] The forearm module includes an outer forearm fixing frame, a fixing frame connecting plate, an inner forearm fixing frame, a forearm module, and a ballhand module. The outer forearm fixing frame is provided with an output flange limiter, which is fixedly connected to the elbow joint module by bolts, and works together with the outer forearm fixing frame of the elbow joint module to realize the anthropomorphic limit of the forearm module. The fixing frame connecting plate is fixedly connected to the outer forearm fixing frame, the inner forearm fixing frame, and the forearm module by bolts. The inner forearm fixing frame is fixedly connected to the elbow joint bearing end cover by bolts, and the ballhand module is fixedly connected to the forearm module by bolts. When the robot arm parts are subjected to impact force, the impact force will be transmitted to the second stepped flange bearing on the elbow joint module, and the second stepped flange bearing is fixedly connected to the inner fixed frame of the elbow joint module. At this time, the impact force will be unloaded to the parts.

[0015] Further: the flexion / extension module also includes a flexion / extension joint fixing frame, one end of the flexion / extension joint fixing frame is fixed on the flexion / extension joint module, and a mounting through hole is provided on it. The abduction / adduction joint coupling block is installed on the flexion / extension joint fixing frame by bolts and is connected to the flexion / extension joint module.

[0016] Furthermore: the bearing end cover is interference fit with the first stepped flange bearing inner ring and is arranged to rotate along with the first stepped flange bearing inner ring.

[0017] Furthermore: a flange limiting step is provided on the upper end surface of the lower fixing frame of the internal / external rotation joint module, the outer ring of the flange limiting step is transitionally matched with the upper fixing frame of the internal / external rotation joint module, and the internal / external rotation joint module is fixed to the flange limiting step by bolts.

[0018] Furthermore: the inner / outer rotation module also includes a bolt magnetic cover plate, and the bolt magnetic cover plate is respectively installed on the side of the coupling block and the coupling block fixing frame.

[0019] Furthermore: vertical grooves are arranged at equal intervals on the golfer module.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This utility model can achieve anthropomorphic arm freedom. This utility model fully considers the range of freedom of the human arm, and takes humans as the main reference object in the structure and range of freedom. The flexion / extension, abduction / adduction, internal / external rotation, and the freedom range are consistent with the human body.

[0022] 2. This utility model can achieve low moment of inertia. The overall structural layout of the robotic arm, including the flexion / extension module, abduction / adduction module, internal / external rotation module, and forward / backward rotation module, has the center of mass of each module on the rotation axis, greatly reducing the moment of inertia.

[0023] 3. The utility model adopts modular design, which is extremely convenient for assembly and provides a good foundation for mass production and assembly.

[0024] 4. This utility model has advantages in low cost, good compatibility, simple installation and easy operation, and can be promoted in multiple industrial scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the overall structural front view of the four-degree-of-freedom robotic arm structure;

[0026] Figure 2 This is the overall rear view of the four-degree-of-freedom robotic arm structure;

[0027] Figure 3 This is a model diagram of the flexion / extension module of the four-degree-of-freedom robotic arm;

[0028] Figure 4 This is the exploded diagram of the specific model of the extension / adduction module;

[0029] Figure 5 This is a cross-sectional view of the specific model of the abduction / adduction module;

[0030] Figure 6 Exploded view of the internal / external rotation module;

[0031] Figure 7 Cross-section of the internal / external rotation module;

[0032] Figure 8 Exploded diagram of the specific connections of the elbow joint module;

[0033] Figure 9 Specific connection cross-section of the elbow joint module;

[0034] Figure 10 Model diagram of the forearm module.

[0035] List of reference numerals:

[0036] 1. Flexion / extension module; 101. Flexion / extension joint module; 102. Flexion / extension joint fixator;

[0037] 2. Abduction / adduction module; 201. Abduction / adduction joint front fixator; 202. Abduction / adduction joint module; 203. Abduction / adduction joint coupling block; 204. Abduction / adduction joint rear fixator; 205. First stepped flange bearing; 206. Bearing end cap; 207. Limit step; 208. Flange bearing limiter;

[0038] 3. Internal / external rotation module; 301. Bolt magnetic cover; 302. Coupling block; 303. Coupling block fixing bracket; 304. Internal / external rotation joint module upper fixing bracket; 305. Internal / external rotation joint module; 306. Internal / external rotation joint module lower fixing bracket; 307. Limiting flange; 308. Flange limiting step;

[0039] 4. Elbow joint module; 401. Elbow joint module outer fixing frame; 402. Elbow joint module; 403. Elbow joint coupling block; 404. Elbow joint bearing end cover; 405. Second stepped flange bearing; 406. Elbow joint module inner fixing frame; 407. Limit cover;

[0040] 5. Forearm module; 501. Forearm outer fixing bracket; 502. Fixing bracket connecting plate; 503. Forearm inner fixing bracket; 504. Forearm module; 505. Hand module; 506. Output flange limiter. DETAILED DESCRIPTION

[0041] The present invention is described in further detail below with reference to the accompanying drawings and specific embodiments:

[0042] like Figure 1-2As shown, the utility model proposes a four-degree-of-freedom robotic arm structure, which is installed on the rotation axis of the humanoid robot, including a flexion / extension module 1, an abduction / adduction module 2, an internal / external rotation module 3, an elbow joint module 4 and a forearm module 5. The center of mass of each module is on the rotation axis, which can greatly reduce the moment of inertia when working.

[0043] like Figure 3 As shown, the flexion / extension module 1 is used to realize the abduction / adduction freedom of the robotic arm, which includes a flexion / extension joint module 101. The abduction / adduction module 2 is connected to the flexion / extension joint module 101, and the flexion / extension joint module 101 is adjusted by the flexion / extension joint module 101. The flexion / extension module 1 also includes a flexion / extension joint fixing frame 102, one end of the flexion / extension joint fixing frame 102 is fixed on the flexion / extension joint module 101, and a mounting through hole is provided thereon. The abduction / adduction joint coupling block 203 is installed on the flexion / extension joint fixing frame 102 by bolts and is connected to the flexion / extension joint module 101. The flexion / extension joint module 101 is installed and fixed to the upper body of the humanoid robot.

[0044] like Figure 4-5 As shown, the abduction / adduction module 2 is used to realize the abduction / adduction freedom of the robotic arm, which includes an abduction / adduction joint front fixation frame 201, an abduction / adduction joint module 202, an abduction / adduction joint coupling block 302, an abduction / adduction joint rear fixation frame 204, a first stepped flange bearing 205, and a bearing end cover 206. The abduction / adduction joint coupling block 302 is fixedly connected to the flexion / extension joint module 101 by bolts. The outer sides of the abduction / adduction joint front fixation frame 201 and the abduction / adduction joint rear fixation frame 204 are respectively provided with a limit step 207. The abduction / adduction joint coupling block 302 is located on the limit step 20 7, and are respectively fixedly connected to the abduction / adduction joint front fixation frame 201 and the abduction / adduction joint rear fixation frame 204 by bolts to lock their axial movement. The abduction / adduction joint module 202 is located between the abduction / adduction joint front fixation frame 201 and the abduction / adduction joint rear fixation frame 204. A flange bearing limiter 208 is provided on the outer side of the abduction / adduction joint rear fixation frame 204. The inner ring of the first stepped flange bearing 205 is fixedly connected to the flange bearing limiter 208. At the same time, the bearing end cover 206 presses the outer ring of the first stepped flange bearing 205 and is fixedly connected to the abduction / adduction joint rear fixation frame 204 to lock its axial movement.

[0045] like Figure 6-7As shown, the internal / external rotation module 3 is used to realize the internal / external rotation freedom of the robot arm, which includes a coupling block 302, a coupling block 302 fixing frame, an internal / external rotation joint module upper fixing frame 304, an internal / external rotation joint module 305, and an internal / external rotation joint module lower fixing frame 306. The internal / external rotation joint module 305 is installed on the internal / external rotation joint module lower fixing frame 306, the internal / external rotation joint module upper fixing frame 304 is sleeved on the internal / external rotation joint module 305 and fixed on the internal / external rotation joint module lower fixing frame 306, the coupling block 302 and the external rotation joint module are connected. The abduction / adduction joint module 202 is fixedly connected by bolts, the coupling block 302 is provided with a limiting flange 307, the abduction / adduction joint front fixation frame 201 is provided with a first limiting groove, the limiting flange 307 is installed in the first limiting groove, realizing anthropomorphic limitation of the abduction / adduction degree of freedom within the limit, the coupling block 302 and the coupling block 302 fixing frame are fixedly connected by bolts, the coupling block 302 and the coupling block 302 fixing frame are respectively provided with a second limiting groove, and transitionally cooperate with the fixing frame 304 on the internal / external rotation joint module, and are fixedly connected by bolts;

[0046] like Figure 8-9 As shown, the elbow joint module 4 is used to realize the elbow joint freedom of the robot arm, which includes an elbow joint module outer fixing frame 401, an elbow joint module 402, an elbow joint coupling block 403, an elbow joint bearing end cover 404, a second stepped flange bearing 405, and an elbow joint module inner fixing frame 406. The elbow joint module outer fixing frame 401 and the elbow joint module inner fixing frame 406 are respectively provided with a third limiting groove, which is connected to the pin provided on the elbow joint coupling block 403 and is fixedly connected by bolts. The other end of the elbow joint coupling block 403 is provided with a limit cover 407, which works together with the lower fixing frame 306 of the internal / external rotation joint module to achieve anthropomorphic limiting of the elbow joint module 4. The outer ring of the second stepped flange bearing 405 is interference fit with the inner fixing frame 406 of the elbow joint module, and its inner ring is interference fit with the protrusion of the elbow joint bearing end cover 404. One side of the elbow joint bearing end cover 404 presses the second stepped flange bearing 405 to fix the stepped flange bearing and prevent it from axial movement.

[0047] like Figure 10As shown, the forearm module 5 is used to realize the forearm freedom of the robot arm, which includes a forearm outer fixing frame 501, a fixing frame connecting plate 502, a forearm inner fixing frame 503, a forearm module 504, and a hand module 505. The forearm outer fixing frame 501 is provided with an output flange limiter 506, which is fixedly connected to the elbow joint module 402 by bolts and works together with the elbow joint module outer fixing frame 401 to realize the anthropomorphic limit of the forearm module 5. The fixing frame connecting plate 502 is connected to the forearm outer fixing frame 501 and the forearm inner fixing frame 503 by bolts. , the forearm module 504 is fixedly connected, the forearm inner fixing frame 503 is fixedly connected to the elbow joint bearing end cover 404 by bolts, and the hand module 505 is fixedly connected to the forearm module 504 by bolts. When the robot arm parts are subjected to impact force, the impact force will be transmitted to the second stepped flange bearing 405 on the elbow joint module 402, and the second stepped flange bearing 405 is fixedly connected to the inner fixing frame of the elbow joint module 402. At this time, the impact force will be unloaded to the parts, which greatly reduces the force on the front drive / rear extension joint module, reduces loss, and improves repositioning accuracy.

[0048] The bearing end cover 206 is interference fit with the inner ring of the first stepped flange bearing 205 and is arranged to rotate along with the inner ring of the first stepped flange bearing 205 .

[0049] A flange limiting step 308 is provided on the upper end surface of the lower fixing frame 306 of the internal / external rotation joint module. The outer ring of the flange limiting step 308 transitionally fits with the upper fixing frame 304 of the internal / external rotation joint module. The internal / external rotation joint module 305 is fixed to the flange limiting step 308 by bolts.

[0050] The inner / outer rotation module 3 further includes a bolt magnetic cover plate 301 , which is respectively mounted on the side of the coupling block 302 and the side of the coupling block 302 fixing frame.

[0051] The golfer module 505 is provided with vertical grooves at equal intervals.

[0052] The four-degree-of-freedom robotic arm structure proposed in the present invention is installed on a humanoid robot. The specific structure of the four-degree-of-freedom robotic arm structure refers to the above-mentioned embodiments. Since the humanoid robot adopts all the technical solutions of all the above-mentioned embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0053] The humanoid robot includes a drive motor, a rotating shaft, and a housing. The drive motor drives the rotating shaft, which in turn drives the movement of a four-degree-of-freedom robotic arm. The four-degree-of-freedom robotic arm is a purely mechanical structure, making it more stable.

[0054] By setting the above structure, the utility model can achieve the following technical effects:

[0055] 1. This utility model can achieve anthropomorphic arm freedom. This utility model fully considers the range of freedom of the human arm, and takes humans as the main reference object in the structure and range of freedom. The flexion / extension, abduction / adduction, internal / external rotation, and the freedom range are consistent with the human body.

[0056] 2. This utility model can achieve low moment of inertia. The overall structural layout of the robotic arm, including the flexion / extension module 1, the abduction / adduction module 2, the internal / external rotation module 3, and the forward / backward movement module, has the center of mass of each module on the rotation axis, greatly reducing the moment of inertia.

[0057] 3. The utility model adopts modular design, which is extremely convenient for assembly and provides a good foundation for mass production and assembly.

[0058] 4. This utility model has advantages in low cost, good compatibility, simple installation and easy operation, and can be promoted in multiple industrial scenarios.

[0059] The above description is merely a preferred embodiment of the present invention and does not constitute any other limitation to the present invention. Any modification or equivalent variation based on the technical essence of the present invention shall still fall within the scope of protection claimed by the present invention.

Claims

1. A four-degree-of-freedom robotic arm structure, mounted on a rotating shaft of a humanoid robot, characterized in that: It includes a flexion / extension module (1), an abduction / adduction module (2), an internal / external rotation module (3), an elbow joint module (4) and a forearm module (5), and the center of mass of each module is on the rotation axis. The flexion / extension module (1) includes a flexion / extension joint module (101), and the abduction / adduction module (2) is connected to the flexion / extension joint module (101); The abduction / adduction module (2) comprises an abduction / adduction joint front fixing frame (201), an abduction / adduction joint module (202), an abduction / adduction joint coupling block (203), an abduction / adduction joint rear fixing frame (204), a first stepped flange bearing (205), and a bearing end cover (206); the abduction / adduction joint coupling block (203) is fixedly connected to the flexion / extension joint module (101) by bolts; the outer sides of the abduction / adduction joint front fixing frame (201) and the abduction / adduction joint rear fixing frame (204) are respectively provided with limiting steps (207); the abduction / adduction joint coupling block (203) is located on the limiting steps (207); 7) and are respectively fixedly connected to the abduction / adduction joint front fixing frame (201) and the abduction / adduction joint rear fixing frame (204) by bolts, the abduction / adduction joint module (202) is located between the abduction / adduction joint front fixing frame (201) and the abduction / adduction joint rear fixing frame (204), a flange bearing limiter (208) is provided on the outside of the abduction / adduction joint rear fixing frame (204), the inner ring of the first stepped flange bearing (205) is fixedly connected to the flange bearing limiter (208), and the bearing end cover (206) presses the outer ring of the first stepped flange bearing (205) and is fixedly connected to the abduction / adduction joint rear fixing frame (204); The internal / external rotation module (3) comprises a coupling block (302), a coupling block fixing frame (303), an internal / external rotation joint module upper fixing frame (304), an internal / external rotation joint module (305), and an internal / external rotation joint module lower fixing frame (306); the internal / external rotation joint module (305) is mounted on the internal / external rotation joint module lower fixing frame (306); the internal / external rotation joint module upper fixing frame (304) is sleeved on the internal / external rotation joint module (305) and fixed on the internal / external rotation joint module lower fixing frame (306); the coupling block (302) and the abduction / adduction joint module are connected. (202) is fixedly connected by bolts, the coupling block (302) is provided with a limiting flange (307), the abduction / adduction joint front fixing frame (201) is provided with a first limiting groove, the limiting flange (307) is installed in the first limiting groove, realizing anthropomorphic limiting of the abduction / adduction freedom within the limit, the coupling block (302) and the coupling block fixing frame (303) are fixedly connected by bolts, the coupling block (302) and the coupling block fixing frame (303) are respectively provided with a second limiting groove, and transitionally matched with the internal / external rotation joint module upper fixing frame (304), and fixedly connected by bolts; The elbow joint module (4) comprises an elbow joint module outer fixing frame (401), an elbow joint module (402), an elbow joint coupling block (403), an elbow joint bearing end cover (404), a second stepped flange bearing (405), and an elbow joint module inner fixing frame (406). The elbow joint module outer fixing frame (401) and the elbow joint module inner fixing frame (406) are respectively provided with a third limiting groove, which is connected to a pin provided on the elbow joint coupling block (403) and is fixed by a bolt. The elbow joint coupling block (403) is fixedly connected, and a limiting cover (407) is provided at the other end thereof, and works together with the lower fixing frame (306) of the internal / external rotation joint module to realize the anthropomorphic limiting of the elbow joint module (4); the outer ring of the second stepped flange bearing (405) is interference-fitted with the inner fixing frame (406) of the elbow joint module, and the inner ring thereof is interference-fitted with the protrusion of the elbow joint bearing end cover (404); and one side of the elbow joint bearing end cover (404) presses the second stepped flange bearing (405); The forearm module (5) comprises a forearm outer fixing frame (501), a fixing frame connecting plate (502), a forearm inner fixing frame (503), a forearm module (504), and a golfer module (505). The forearm outer fixing frame (501) is provided with an output flange limiter (506), which is fixedly connected to the elbow joint module (402) by bolts and acts together with the elbow joint module outer fixing frame (401) to achieve anthropomorphic limit of the forearm module (5). The fixing frame connecting plate (502) is fixedly connected to the forearm outer fixing frame (501) and the elbow joint module by bolts. The inner side fixing frame (503) of the forearm and the forearm module (504) are fixedly connected. The inner side fixing frame (503) of the forearm is fixedly connected to the elbow joint bearing end cover (404) by bolts. The ball player module (505) is fixedly connected to the forearm module (504) by bolts. When the robot arm parts are subjected to impact force, the impact force is transmitted to the second stepped flange bearing (405) on the elbow joint module (402). The second stepped flange bearing (405) is fixedly connected to the inner side fixing frame of the elbow joint module (402). At this time, the impact force is unloaded to the parts.

2. A four-degree-of-freedom robotic arm structure according to claim 1, characterized in that: The flexion / extension module (1) further comprises a flexion / extension joint fixing frame (102), one end of which is fixed on the flexion / extension joint module (101) and is provided with a mounting through hole, and the abduction / adduction joint coupling block (203) is mounted on the flexion / extension joint fixing frame (102) by means of bolts and is connected to the flexion / extension joint module (101).

3. The four-degree-of-freedom robotic arm structure according to claim 1, characterized in that: The bearing end cover (206) is interference-fitted with the inner ring of the first stepped flange bearing (205) and is arranged to rotate following the inner ring of the first stepped flange bearing (205).

4. The four-degree-of-freedom robotic arm structure according to claim 1, characterized in that: The upper end surface of the lower fixing frame (306) of the internal / external rotation joint module is provided with a flange limiting step (308), the outer ring of the flange limiting step (308) is transitionally matched with the upper fixing frame (304) of the internal / external rotation joint module, and the internal / external rotation joint module (305) is fixedly connected to the flange limiting step (308) by bolts.

5. The four-degree-of-freedom robotic arm structure according to claim 1, characterized in that: The inner / outer rotation module (3) further comprises a bolt magnetic cover plate (301), and the bolt magnetic cover plate (301) is respectively mounted on the side surfaces of the coupling block (302) and the coupling block fixing frame (303).

6. The four-degree-of-freedom robotic arm structure according to claim 1, characterized in that: The golfer module (505) is provided with vertical grooves at equal intervals.

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