CN212193202U

CN212193202U - Gear differential type underactuated three-joint manipulator

Info

Publication number: CN212193202U
Application number: CN202020878168.3U
Authority: CN
Inventors: 郭瑞峰; 王晓冬; 李红侠; 李友松; 张琳
Original assignee: Xian University of Architecture and Technology
Current assignee: Xian University of Architecture and Technology
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2020-12-22
Anticipated expiration: 2030-05-22

Abstract

The utility model discloses a gear differential underactuated three-joint manipulator, which comprises three-joint fingers; the three-joint fingers are arranged in 120 degrees, and each three-joint finger comprises a lower knuckle, a middle knuckle and an upper knuckle; the lower knuckle, the middle knuckle and the upper knuckle are connected through gear engagement, decoupling devices for realizing underactuation are respectively arranged on joint shafts at the joints of the lower knuckle, the middle knuckle and the upper knuckle, the lower knuckles of the three-knuckle fingers are respectively connected with a bevel gear transmission system through gears, the bevel gear transmission system is connected with a stepping motor, and the motion control of the three-knuckle fingers is realized by driving the bevel gear transmission system through the stepping motor. The utility model discloses simple structure, drive element are few, can the self-adaptation be grabbed the surface shape of object, and then realize harmless and reliable snatching.

Description

Gear differential type underactuated three-joint manipulator

Technical Field

The utility model belongs to the technical field of mechanical production, concretely relates to gear differential type is owed and is driven three joint manipulators.

Background

With social development and technological progress, robots are widely used in manufacturing industries, and in space exploration where minimum maintenance requirements are emphasized, the use of robots is more attractive. The manipulator, namely the end effector is an important component of the robot, and a single-degree-of-freedom gripper is adopted to complete simple operations such as welding, painting, assembly and the like initially, although the gripper is simple in structure, convenient to control, strong in load capacity and high in reliability, the gripper is single in function and lack of flexibility, the gripper can only work for specific tasks, and once the tasks are changed, the end effector needs to be replaced. Under the circumstances, a multi-joint multi-finger dexterous hand becomes a development trend of a robot end effector due to the anthropomorphic imagery, and the multi-joint multi-finger hand has the advantages of strong shape adaptability and can meet the requirements of various different tasks, but the multi-joint multi-finger hand has the defects of complex structure, difficult control, poor load capacity, low reliability and the like due to the adoption of a large number of serial joints. Therefore, it is necessary to develop a grabbing mechanism which has a simple structure, few driving elements and can adapt to the shape of an object to be grabbed.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that not enough among the above-mentioned prior art is directed against, provide a gear differential type three joint manipulator of underactuated, simple structure, actuating element are few, can the self-adaptation be grabbed the surface shape of object, and then realize harmless and reliable snatching.

The utility model adopts the following technical scheme:

a gear differential type underactuated three-joint mechanical arm comprises three-joint fingers, wherein the three-joint fingers are arranged in an angle of 120 degrees, and a joint shaft of each three-joint finger is respectively provided with a decoupling device serving as an underactuated mechanism; one end of each of the three-joint fingers is connected with a stepping motor through a driving transmission cylindrical gear and a bevel gear transmission system respectively, and the stepping motor drives the bevel gear transmission system to realize the motion transmission and control of the three-joint fingers.

Specifically, the three-joint finger comprises an upper knuckle, a middle knuckle and a lower knuckle which are sequentially connected through gear meshing; an upper knuckle driving gear is arranged at the joint of the upper knuckle and the middle knuckle, a middle knuckle driving gear is arranged at the joint of the middle knuckle and the lower knuckle, the other end of the lower knuckle is fixedly connected with the base finger support, and the lower knuckle driving gear and the drive transmission cylindrical gear are connected with the bevel gear transmission system.

Furthermore, the joint shafts of the lower knuckle, the middle knuckle and the upper knuckle corresponding to the lower knuckle driving gear, the middle knuckle driving gear and the upper knuckle driving gear are respectively provided with a decoupling device.

Furthermore, a lower knuckle limiting device is arranged on the decoupling device at the lower knuckle, a middle knuckle limiting device is arranged on the decoupling device at the middle knuckle, and an upper knuckle limiting device is arranged on the decoupling device at the upper knuckle.

Furthermore, a middle knuckle transmission gear is arranged in the middle knuckle, the upper knuckle drive gear is meshed with the middle knuckle drive gear through the middle knuckle transmission gear, three lower knuckle transmission gears are sequentially arranged in the lower knuckles, and the lower knuckle drive gear is meshed with the middle knuckle drive gear through the three lower knuckle transmission gears.

Specifically, the bevel gear transmission system comprises a first bevel gear, a second bevel gear, a third bevel gear and a fourth bevel gear; the second bevel gear and the third bevel gear are arranged in parallel, the second bevel gear is in meshed connection with the first bevel gear, and the third bevel gear is in meshed connection with the fourth bevel gear; the angles between the second bevel gear and the first bevel gear, between the first bevel gear and the fourth bevel gear, and between the fourth bevel gear and the third bevel gear are all 120 degrees.

Furthermore, an input shaft of the stepping motor is connected with a first bevel gear, a driving cylindrical gear is arranged between the input shaft and the first bevel gear, a second bevel gear is connected with a third bevel gear through a connecting shaft, a second driving cylindrical gear is arranged on the connecting shaft, a fourth bevel gear is connected with a third driving cylindrical gear through a connecting shaft, and each driving cylindrical gear is correspondingly connected with lower knuckle driving gears arranged on three knuckle fingers through a driving transmission cylindrical gear.

Specifically, the decoupling device comprises two friction plates which are in contact with each other, one surface of each friction plate is connected with the shell of the three-joint finger, and the other surface of each friction plate is connected with the adjusting screw through a spring.

Specifically, step motor sets up on the motor support, and awl tooth transmission system sets up in three backup pad, and motor support and backup pad are all fixed on the fixed plate, and the top of backup pad is provided with the holding plate, and the interval is provided with three base finger supports on the holding plate, and three joint fingers that correspond are connected respectively to the base finger support.

Compared with the prior art, the utility model discloses following beneficial effect has at least:

the utility model relates to a gear differential type three joint manipulators of underactuated, because generally indicate only need three joint knuckle just can snatch the object, consequently adopt three joint fingers to it is even to distribute 120 to be favorable to whole manipulator atress. The setting of the decoupling zero device of joint department can avoid whole finger at the unordered state of bending and straightening in-process motion. The transmission system is formed by meshing 4 bevel gears, and the power direction is changed while the power is transmitted.

Furthermore, the three-joint finger structure is arranged to meet the requirement of minimum finger joints when an object is grabbed, and the object can be grabbed better like the fingers of a human.

Furthermore, the decoupling device is a core device which is arranged under the structural design of the whole manipulator and can complete the under-actuated action. The finger joint can transmit power to the next joint to continue moving under the condition that the previous finger is immobilized by a certain acting force.

Furthermore, a differential gear structure is adopted between the joints, so that a certain speed reduction effect can be met under the condition of accurate transmission. Thus, a large moment can be obtained in the posterior joint in addition to overcoming the friction of the decoupling device.

Furthermore, the transmission system is arranged according to a certain space structure by using four bevel gears. Mainly for transmitting power to 3 three-joint fingers distributed at 120 degrees. The four bevel gears are simultaneously provided with power transmission cylindrical gears. Whole bevel gear transmission system structural arrangement can not only satisfy the input of power supply, can also be through transmission and change direction of motion, transmits the motion for 3 mechanical fingers through 3 power transmission cylindrical gear above that.

Furthermore, the decoupling device is structurally designed to achieve a core device of an under-actuated structure and is simple in structure. The friction force generated by the two friction plates under the pressure of the adjusting screw is a pre-tightening force which needs to be overcome when each joint rotates, and joint fingers can rotate in sequence when an object is grabbed.

Furthermore, the arrangement of each support of the whole manipulator can not only meet the distribution of the space positions of a bevel gear transmission system, but also meet the installation positions of motors and the installation of 120-degree distribution of three-joint fingers, and the support in the whole structure is simple in structure while meeting the structural requirements.

The utility model also discloses a gear differential type underactuated three joint manipulator's operation method, bevel gear transmission system take place to rotate under step motor's power input, change the power direction simultaneously, give three joint fingers with power transmission through power transmission cylindrical gear. Meanwhile, under the assistance of the limiting device and the decoupling device, the three-joint finger can realize opening and closing actions under the condition of transmitting motion through the differential gear. The whole system has compact structure and simple and convenient operation method.

To sum up, the utility model discloses not only realized beyond the manipulator function, still designed novel transmission system structure to and the finger takes place pivoted differential gear transmission system. Different devices and structures are assembled, and a novel under-actuated manipulator structure is designed. Not only meets the requirements of actual conditions, but also provides a new design concept and a new design mode in the design of the manipulator structure. The development of the whole manipulator industry is facilitated, and the development of the robot structure can be promoted.

The technical solution of the present invention is further described in detail by the accompanying drawings and examples.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is the finger model with the base shell removed according to the present invention;

FIG. 3 is a schematic view of the finger structure of the present invention;

FIG. 4 is a schematic view of a rotating device of the present invention;

FIG. 5 is a structural diagram of the gear transmission of the present invention;

fig. 6 is a side view of the gear transmission structure of the present invention;

fig. 7 is a schematic diagram of the bevel gear spatial distribution position of the present invention;

FIG. 8 is a schematic view of the decoupling assembly of the present invention;

fig. 9 is a schematic view of the finger deployment according to the present invention;

fig. 10 is a schematic diagram of the adaptive grabbing process of the present invention, in which (a) is the initial position, (b) is the lower knuckle contacting the object, (c) is the middle knuckle contacting the object, and (d) is the upper knuckle contacting the object.

Wherein: 1. a motor support; 2. a stepping motor; 3. a base finger support; 4. three joint fingers; 5. a holding plate; 6. a support plate; 7. a fixing plate; 8. an input shaft; 9. a bevel gear transmission system; 10. a drive transmission cylindrical gear; 11. a decoupling device; 12. a lower finger joint axis; 13. a lower knuckle; 14. a middle finger joint axis; 15. a middle knuckle; 16. an upper finger joint axis; 17. an upper knuckle; 18-1. a lower knuckle drive gear; 18-2. a middle knuckle drive gear; 18-3. an upper knuckle drive gear; 19. a middle knuckle transfer gear; 20. a lower knuckle transfer gear; 23. a first bevel gear; 24. a second bevel gear; 25. a third bevel gear; 26. a fourth bevel gear; 27. a drive cylindrical gear; 28. a friction plate; 29. a spring; 30. and adjusting the screw.

Detailed Description

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected" and "connected" are to be construed broadly, and may for example be movably, fixedly, detachably or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Please refer to fig. 1 and 2, the utility model relates to a gear differential type underactuated three-joint manipulator, adopt gear drive, adopt the decoupling zero device to be underactuated mechanism, snatch through three joint fingers 4, snatch the mode and snatch for the inboard contact of finger, whole mechanical finger structure size is little, and control is simple and convenient, satisfies to snatch and fine operation. The method comprises the following steps:

the device comprises a motor support 1, a stepping motor 2, a base finger support 3, a three-joint finger 4, a retaining plate 5, a supporting plate 6 and a fixing plate 7. The motor support 1 and the three support plates 6 are respectively arranged on the fixing plate 7, the stepping motor 2 is arranged on the motor support 1, the three support plates 6 are internally provided with a bevel gear transmission system 9, and the bevel gear transmission system 9 comprises four bevel gears with 30-degree indexing conical angles which are meshed to form a transmission system; the stepping motor 2 is connected with a bevel gear transmission system 9 through an input shaft 8; a holding plate 5 is arranged above the supporting plate 6, and the three base finger supports 3 are arranged on the holding plate 5 at intervals and used for fixing three-joint fingers 4; the bevel gear transmission system 9 is respectively connected with the three-joint fingers 4 through the decoupling device 11, and the stepping motor 2 controls the three-joint fingers 4 to perform grabbing operation through the bevel gear transmission system 9.

Referring to fig. 3, the three-joint finger 4 includes an upper knuckle 17, a middle knuckle 15 and a lower knuckle 13. One end of a lower knuckle 13 is arranged on the base finger support 3 and is connected with the bevel gear transmission system 9 through a lower knuckle drive gear 18-1, the other end of the lower knuckle is connected with one end of a middle knuckle 15 through a middle knuckle drive gear 18-2, the other end of the middle knuckle 15 is connected with an upper knuckle 17 through an upper knuckle drive gear 18-3, a middle knuckle transmission gear 19 is arranged in the middle knuckle 15, the upper knuckle drive gear 18-3 is meshed and connected with the middle knuckle drive gear 18-2 through the middle knuckle transmission gear 19, three lower knuckle transmission gears 20 are sequentially arranged in the lower knuckle 13, and the lower knuckle drive gear 18-1 is meshed and connected with the middle knuckle drive gear 18-2 through the three lower knuckle transmission gears 20; the lower knuckle driving gear 18-1 and the lower knuckle 13 are connected with the lower knuckle shaft 12, the middle knuckle driving gear 18-2 and the middle knuckle 15 are connected with the middle knuckle shaft 14, and the upper knuckle driving gear 18-3 and the upper knuckle 17 are connected with the upper knuckle shaft 16; lower knuckle driving gears 18-1 corresponding to the three-joint fingers 4 are respectively in meshed connection with a bevel gear transmission system 9 through a driving transmission cylindrical gear 10, and the three-joint fingers 4 are distributed separately in position through bevel gear transmission; in order to avoid the disordered state of the motion of the whole finger in the bending and straightening processes, a decoupling device is arranged at the finger joint, and a decoupling device 11 is respectively arranged at the lower finger joint shaft 12, the middle finger joint shaft 14 and the upper finger joint shaft 16.

The finger has certain grabbing shape adaptability. The finger parts are made of hard aluminum alloy, the strength is high, the rigidity is good, the weight is light, and the rotating pin shaft is made of stainless steel materials. The brass sleeves are arranged in the positioning holes of the fingers and can reduce the friction resistance in the movement process.

Referring to fig. 4, three base finger supports 3 are uniformly distributed on the holding plate 5 at 120 degrees and are respectively connected with one three-joint finger 4, and the three-joint fingers 4 of the under-actuated manipulator can rotate around the corresponding base finger supports 3 relatively and can rotate 90 degrees, so that the three fingers rotate from a state where the three points are opposite to each other to a state where the three fingers touch an object to be grasped. The three base finger supports 3 are mutually attached to form three included angles of 120 degrees in space, and the motion and sequence control of the three-joint fingers 4 are realized by matching with a 120-degree bevel gear transmission system.

Referring to fig. 5 and 6, the bevel gear system 9 includes a first bevel gear 23, a second bevel gear 24, a third bevel gear 25, a fourth bevel gear 26 and a driving cylindrical gear 27; the second bevel gear 24 and the third bevel gear 25 are arranged in parallel on the same shaft; the first bevel gear 23 is in meshed connection with the second bevel gear 24, and the third bevel gear 25 is in meshed connection with the fourth bevel gear 26; the angles between the second bevel gear 24 and the first bevel gear 23, between the first bevel gear 23 and the fourth bevel gear 26, and between the fourth bevel gear 26 and the third bevel gear 25 are all 120 degrees, so that the synchronous motion of the three-joint fingers is realized, and the spatial layout of the three-joint fingers 4 is 120 degrees. The three bevel gear shafts are respectively provided with a cylindrical gear 27 which rotates together with the bevel gears.

And a drive transmission cylindrical gear 10 is arranged between each three-joint finger 4 and a corresponding drive cylindrical gear 27 on the bevel gear transmission system 9, the drive cylindrical gears 27 are in meshed connection with the drive transmission cylindrical gears 10, and the lower knuckle drive gears 18-1 on the three-joint fingers 4 are sequentially connected with the first bevel gear 23, the second bevel gear 24, the third bevel gear 25 and the fourth bevel gear 26 through the drive transmission cylindrical gears 10 and the drive cylindrical gears 27.

An input shaft 8 of the stepping motor 2 is connected with a first bevel gear 23, a driving cylindrical gear 27 is arranged between the input shaft 8 and the first bevel gear 23, a second bevel gear 24 is connected with a third bevel gear 25 through a connecting shaft, a second driving cylindrical gear 27 is arranged on the connecting shaft, and a fourth bevel gear 26 is connected with the third driving cylindrical gear 27 through the connecting shaft; the three driving cylindrical gears 27 are uniformly distributed in 120 degrees, and each driving cylindrical gear 27 is correspondingly engaged and connected with the lower knuckle driving gear 18-1 arranged on the three-knuckle fingers 4 through one driving transmission cylindrical gear 10. Four 120-degree transmission bevel gears are adopted, and the bevel gears and the corresponding driving cylindrical gears 27 are fixed together and can coaxially rotate along with the rotation among the bevel gears.

Referring to fig. 6 and 7, the stepping motor 2 is fixed on the motor support 1, the input shaft 8 rotates to drive the first bevel gear 23 and the driving cylindrical gear 27 fixed on the same shaft, and the first bevel gear 23 and the second bevel gear 24 are engaged with each other, so that the second bevel gear 24 rotates along with the first bevel gear 23; and because the taper angles of the first bevel gear 23 and the second bevel gear 24 are respectively 30 degrees, the intersection angle of the two shafts is 60 degrees. The second bevel gear 24 and the third bevel gear 25 are on the same shaft, so the third bevel gear 25 rotates coaxially with the second bevel gear 24, the fourth bevel gear 26 is meshed with the third bevel gear 25, and the fourth bevel gear 26 also starts to rotate. Therefore, the motion of the first bevel gear 23, the second bevel gear 24, the third bevel gear 25, and the fourth bevel gear 26 is transmitted to the three-joint fingers 4 through the three driving cylindrical gears 27, so that the three-joint fingers are rotated.

Referring to fig. 8, the decoupling assembly 11 includes a friction plate 28, a spring 29 and an adjusting screw 30; one side of the friction plate 28 is in contact connection with the outer shell of the three-joint finger, the other side of the friction plate is connected with an adjusting screw 30 through a spring 29, and the adjusting screw 30 compresses the spring 29 to enable the spring 29 to generate pretightening force; the spring 29 presses the friction plate 28 against a fixed hold against the knuckle housing. The three driving transmission cylindrical gears 10 respectively transmit the motion to three corresponding lower knuckle driving gears 8-1, and a decoupling device 11 fixed on the same joint shaft with the lower knuckle driving gears 8-1 rotates along with the shaft, because friction force acts between a friction plate in the decoupling device and a shell of the lower knuckle 13, the lower knuckle 13 can simultaneously rotate along with the joint shaft 12 and the decoupling device 11 to drive the lower knuckle 13 to rotate, and the lower knuckle 13 drives the whole finger to rotate.

Referring to fig. 3 and 9, when the lower knuckle driving gear 8-1 rotates to drive the corresponding decoupling device 11 to rotate, the corresponding decoupling device 11 drives the lower knuckle 13 to rotate, the lower knuckle 13 and the whole finger start to rotate around the shaft, and after the lower knuckle touches an object, the friction force in the decoupling device 11 is not enough to overcome the blocking force of the object to the lower knuckle, so that the lower knuckle 13 stops rotating around the shaft, and the lower knuckle driving gear 8-1 can still continue to rotate to drive the three lower knuckle transmission gears 20 to rotate, thereby driving the middle knuckle driving gear 18-2 to rotate; the middle knuckle drive gear 18-2 rotates to drive the decoupling device 11 at the middle knuckle to rotate, the decoupling device 11 at the middle knuckle and the friction force in the shell of the middle knuckle 15 drive the middle knuckle 15 to rotate, the middle knuckle 15 and the upper knuckle start to rotate around a shaft, after the middle knuckle touches an object, the friction force in the corresponding decoupling device 11 is not enough to overcome the blocking force of the object to the middle knuckle, and the middle knuckle 15 stops rotating around the shaft; and similarly, the upper knuckle is pushed to move until the whole finger envelops the object. The other two three-joint fingers 4 work by the same principle. The three-joint fingers 4 are also under-actuated, the movement of the three-joint fingers is not interfered with each other, and various irregular special-shaped objects can be grabbed.

After the object is gripped, the stepping motor 2 continues to operate and the gear continues to rotate, which corresponds to the gear being idle. When the object is grabbed, the motor fails or stops supplying power, and the fingers cannot be automatically released due to friction force acting on each joint.

When the user releases to hold an object, the stepping motor 2 rotates reversely, when power is transmitted to the lower knuckle driving gear 8-1, the rotating direction of the stepping motor is opposite to that of the previous rotating direction, the lower knuckle driving gear 8-1 drives the corresponding decoupling device 11 to rotate, the decoupling device 11 drives the lower knuckle 13 to rotate, the lower knuckle 13 and the whole finger start to expand around the shaft, and after the lower knuckle touches the lower knuckle limiting block, the friction force in the decoupling device 11 is not enough to overcome the blocking force of the limiting block on the lower knuckle, so that the lower knuckle 13 stops rotating around the shaft; then the lower knuckle driving gear 8-1 transmits the power to the middle knuckle driving gear 8-2 through the three lower knuckle transmission gears 20; the middle knuckle driving gear 8-2 drives the middle knuckle, and the upper knuckle is opened; after the middle knuckle touches the middle knuckle limiting block, the middle knuckle stops rotating around the shaft; then the power is transmitted to the upper knuckle through the middle knuckle transmission gear 19, and similarly, the upper knuckle is opened, and the mechanical fingers are restored to the initial opened state.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention, as generally described and illustrated in the figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the accompanying drawings, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Fig. 10 shows an analysis model of the adaptive grabbing process when the robot grasps a ball placed on the palm. The initial positions of the three-jointed fingers 4 with respect to the sphere are shown in fig. 10 (a). The three-joint fingers 4 start to move, after the lower knuckle touches the ball, the resistance of the ball to the lower knuckle reaches the frictional damping force generated by the spring in the decoupling device, and then the lower knuckle stops moving, as shown in fig. 10(b), because the friction force exists in the friction plates of the decoupling device of the middle knuckle and the upper knuckle, the middle knuckle and the upper knuckle continue moving, and the middle knuckle also stops moving after touching the ball, as shown in fig. 10 (c). The friction plate of the upper knuckle decoupling device has friction force, the upper knuckle continues moving until the ball body is touched, the whole finger keeps the holding posture, and the position relation of the mechanical arm and the ball body is shown in fig. 10 (d).

The movements between the three fingers are also independent of each other. When the three fingers do not touch the object, the three fingers can move simultaneously, and when one finger stops moving due to the fact that the object is touched by the finger and the resistance force is generated, the other two fingers continue to move; when the other finger stops moving due to the obstruction force when touching the object, the third finger continues moving; when the third finger stops moving due to the obstruction force of touching the object, all three fingers touch the holding object. When the robot continues to move, the knuckles of the three hands respectively start to move independently, so that various special-shaped objects with different geometric shapes can be grabbed.

The above contents are only for explaining the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical solution according to the technical idea of the present invention all fall within the protection scope of the claims of the present invention.

Claims

1. A gear differential type underactuated three-joint manipulator is characterized by comprising three-joint fingers (4), wherein the three-joint fingers (4) are arranged in an angle of 120 degrees, and a joint shaft of each three-joint finger (4) is respectively provided with a decoupling device (11) serving as an underactuated mechanism; one end of each of the three-joint fingers (4) is connected with the stepping motor (2) through the driving transmission cylindrical gear (10) via the bevel gear transmission system (9), and the stepping motor (2) drives the bevel gear transmission system (9) to realize the motion transmission and control of the three-joint fingers (4).

2. The gear differential under-actuated three-joint manipulator according to claim 1, characterized in that the three-joint finger (4) comprises an upper knuckle (17), a middle knuckle (15) and a lower knuckle (13) which are connected in sequence by gear engagement; an upper knuckle driving gear (18-3) is arranged at the joint of the upper knuckle (17) and the middle knuckle (15), a middle knuckle driving gear (18-2) is arranged at the joint of the middle knuckle (15) and the lower knuckle (13), the other end of the lower knuckle (13) is fixedly connected with the base finger support (3), and is connected with the bevel gear transmission system (9) through the lower knuckle driving gear (18-1) and the drive transmission cylindrical gear (10).

3. The gear differential underactuated three-knuckle manipulator according to claim 2, wherein the lower knuckle (13), the middle knuckle (15) and the upper knuckle (17) of the lower knuckle drive gear (18-1), the middle knuckle drive gear (18-2) and the upper knuckle drive gear (18-3) are respectively provided with a decoupling device (11) on their knuckle axes.

4. The gear differential type underactuated three-knuckle manipulator according to claim 3, wherein a lower knuckle limiting device (12) is arranged on the decoupling device (11) at the lower knuckle (13), a middle knuckle limiting device (14) is arranged on the decoupling device (11) at the middle knuckle (15), and an upper knuckle limiting device (16) is arranged on the decoupling device (11) at the upper knuckle (17).

5. The gear differential underactuated three-knuckle manipulator according to claim 2, wherein a middle knuckle transfer gear (19) is arranged in the middle knuckle (15), the upper knuckle drive gear (18-3) is in meshed connection with the middle knuckle drive gear (18-2) through the middle knuckle transfer gear (19), three lower knuckle transfer gears (20) are sequentially arranged in the lower knuckle (13), and the lower knuckle drive gear (18-1) is in meshed connection with the middle knuckle drive gear (18-2) through the three lower knuckle transfer gears (20).

6. The gear differential under-actuated three-joint manipulator according to claim 1, characterized in that the bevel gear transmission system (9) comprises a first bevel gear (23), a second bevel gear (24), a third bevel gear (25) and a fourth bevel gear (26); the second bevel gear (24) and the third bevel gear (25) are arranged in parallel, the second bevel gear (24) is in meshed connection with the first bevel gear (23), and the third bevel gear (25) is in meshed connection with the fourth bevel gear (26); the angles between the second bevel gear (24) and the first bevel gear (23), between the first bevel gear (23) and the fourth bevel gear (26), and between the fourth bevel gear (26) and the third bevel gear (25) are all 120 degrees.

7. The gear differential type underactuated three-joint manipulator according to claim 6, wherein an input shaft (8) of the stepping motor (2) is connected with a first bevel gear (23), a driving cylindrical gear (27) is arranged between the input shaft (8) and the first bevel gear (23), a second bevel gear (24) and a third bevel gear (25) are connected through a connecting shaft, a second driving cylindrical gear (27) is arranged on the connecting shaft, a fourth bevel gear (26) is connected with the third driving cylindrical gear (27) through a connecting shaft, and each driving cylindrical gear (27) is correspondingly connected with a lower knuckle driving gear (18-1) arranged on three-joint fingers (4) through a driving transmission cylindrical gear (10).

8. The gear differential underactuated three-joint manipulator according to claim 1, characterized in that the decoupling device (11) comprises two friction plates (28) in contact with each other, one side of the friction plates (28) being connected to the outer casing of the three-joint finger (4) and the other side being connected to the adjusting screw (30) via a spring (29).

9. The gear differential type underactuated three-joint manipulator according to claim 1, wherein the stepping motor (2) is arranged on the motor support (1), the bevel gear transmission system (9) is arranged on the three support plates (6), the motor support (1) and the support plates (6) are fixed on the fixing plate (7), the holding plate (5) is arranged above the support plates (6), the three base finger supports (3) are arranged on the holding plate (5) at intervals, and the base finger supports (3) are respectively connected with the corresponding three-joint fingers (4).