CN117584169A

CN117584169A - Robot wrist joint

Info

Publication number: CN117584169A
Application number: CN202410031241.6A
Authority: CN
Inventors: 曹宝石; 祁乐; 田昕泽; 李雪皑; 孙永军; 孙奎; 倪风雷; 谢宗武
Original assignee: Harbin Institute of Technology
Current assignee: Harbin Institute of Technology
Priority date: 2024-01-09
Filing date: 2024-01-09
Publication date: 2024-02-23

Abstract

A robot wrist joint belongs to the technical field of robots. The wrist machine I and the wrist joint II form a universal joint structure, the wrist machine I and the wrist joint II are arranged on the bracket and connected with the palm connector, one ends of the two linear drivers are hinged with the palm connector, so that the wrist joint has pitching and deflecting functions, and the other ends of the two linear drivers are connected with the bracket. The sensor design and the mechanical structure are highly integrated, and the arrangement of the vacant space is utilized to ensure that the mechanism has the advantages of small occupied volume and full perception: the double encoder structure can realize high-precision position control, the force sensor can realize force control and flexible control functions and motor end control, and the force sensor structure integrated into the fixed shell is buried in the shell structure and integrated with the linear guide rail, so that the double encoder structure is simpler and more convenient, smaller in size and better in rigidity; the coded disc structure is integrated in the bottom cover, so that the structure is compact and the installation is convenient.

Description

Robot wrist joint

Technical Field

The invention belongs to the technical field of robots, and particularly relates to a wrist joint of a robot.

Background

The robot wrist mechanism is an important component of the robot and is responsible for controlling the posture and the position of the end effector of the robot. In some cases, a flexible wrist is easier to perform a specific function than a flexible hand, and therefore, the design of the wrist is very important in the design of a manipulator. In the existing design of the wrist joint with two degrees of freedom, an extra speed reducer is required, which is difficult to avoid in a series connection type, the occupied space is large, the structure is large, and only a few (such as a bevel gear differential scheme and a tendon scheme) of the wrist joint has the characteristic of coupling two degrees of freedom; most designs of parallel type use spherical parallel mechanisms, and because of the complex structure, interference is easy to occur between parts, and the working space is difficult to guarantee.

In the current movable joint design, the scheme of an air cylinder or a hydraulic cylinder used in the scheme has the problems of excessively complicated mechanism, large occupied volume, easy leakage and the like; the planetary ball screw scheme used in some schemes has the problems of high cost, inconvenient assembly and the like; meanwhile, the occupation volume of the motor is also a problem that has to be considered, and most of the design directions are how to arrange the arrangement of the speed reducer so as to minimize the occupation volume, and the hollow wiring of the speed reducer is difficult to design; because the force sensor is integrated in the modularized joints, the joint rigidity is greatly reduced, the structure is very complex, the force sensor is not integrated in many modularized joints, and a double encoder is rarely adopted, so that the control of the joint moment cannot be realized.

Disclosure of Invention

The present invention is to solve the above-described problems, and further provides a wrist joint of a robot.

The technical scheme adopted by the invention is as follows:

a robot wrist joint comprises a first wrist joint, a second wrist joint, a palm connector, a bracket and two linear drivers; the wrist joint I and the wrist joint II form a universal joint structure, the wrist joint I and the wrist joint II are arranged on the bracket and connected with the palm connector, one ends of the two linear drivers are hinged with the palm connector, so that the wrist joint has pitching and deflecting functions, and the other ends of the two linear drivers are connected with the bracket.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention has the advantages of simple structure, large bearing capacity, high efficiency, high precision, small size, light weight and the like while completing the wrist function, is convenient to route, does not occupy joint space, does not interfere with a joint mechanism, and is convenient to integrate into a robot. And the frameless torque motor, a driver, a sensor and other circuits are integrated into a whole, so that the structure is compact.

2. The invention solves the problems of economy and universality of the movable joint of the robot, integrates the speed reducer and the motion conversion function, greatly reduces the required volume of the mechanism, realizes the function of linear driving with the minimum occupied space volume, and has high motion precision.

3. The sensor design and the mechanical structure are highly integrated, and the arrangement of the vacant space is utilized to ensure that the mechanism has the advantages of small occupied volume and full perception: the double encoder structure integrated into the fixed shell is buried in the shell structure, is integrated with the linear guide rail, is simpler and more convenient, has smaller size and better rigidity; the moment sensor and the code wheel structure are integrated in the bottom cover, so that the structure is compact and the installation is convenient.

4. The linear driver for converting rotary motion into linear motion is a great feature of the design, and the linear driver used by the invention has the advantages of high precision, compact mechanism, high integration of the sensor and full perception, omits the structure of a speed reducer, occupies small volume and is convenient to directly use.

5. The invention has good economy, and the functions of the invention are realized by using more general parts; the structure is simple, the functions are complete, the very important sensors are integrated by utilizing the spare space of the structure, the integral structure and the joint rigidity are not influenced, and the universality is good; the wrist mechanism has complete structure and complete functions, can provide large moment compared with other wrist mechanisms, and simultaneously, the wiring is concentrated at a position which does not interfere with the structure, so that the working space is enlarged, and the overall control is convenient.

Drawings

FIG. 1 is an isometric view of the present invention;

FIG. 2 is an isometric view of a linear drive of the present invention;

FIG. 3 is a front cross-sectional view of a linear actuator of the present invention;

wherein: 1. spherical hinge; 2. a bottom cover; 3. a housing; 4. a top cover; 5. a screw rod; 6. a connecting rod; 7. a guide rail; 8. a slide block; 9. a stator; 10. a rotor; 11. a first connecting piece; 12. a second connecting piece; 13. a nut; 14. a PCB board; 15. a double encoder; 16. a beam; 17. a code wheel; 18. wrist joint I; 19. wrist joint II; 20. a palm connector; 21. a connection cover; 22. a third bearing; 23. a first bearing; 24. a second bearing; 25. and (3) a bracket.

Detailed Description

For a better understanding of the objects, structures and functions of the present invention, reference should be made to the following detailed description of the invention with reference to the accompanying drawings.

As shown in fig. 1 to 3, the robot moving joint of the present invention includes two parts: one part is a linear driver for realizing a linear driving function, and the sensor is integrated in the linear driver part; the other part is a wrist joint realizing mechanism.

The first part of linear driver adopts a frameless motor as a power source, realizes conversion from rotary motion to linear motion by using the cooperation of a lead screw and a linear guide rail, and forms the linear driver by cooperation of various connecting parts; and fish-eye spherical hinges are additionally arranged at two ends of the linear driver respectively, so that the connection between the movable joint and other joints of the robot is realized. Meanwhile, a free space is reserved at the bottom of the linear driver to install a code wheel, and the rotating speed of the motor is detected; the double encoders are arranged in the top boss, and the moment sensor is integrated into the bottom cover 2, so that the structure is simpler, the size is smaller, and the rigidity is better; the sensor is integrated by utilizing the vacant space in structural design, has simple structure, does not occupy extra volume, and has more compact structure and no influence on joint rigidity. The main parts of the frameless motor and the ball screw have the advantages of small occupied volume, good economy and high motion precision, and various degrees of freedom required by two ends of a ball pair provided by the fish-eye ball hinge can be well met, so that the fish-eye ball hinge has the advantage of good generalization.

The wrist joint realizing mechanism of the second part is a 2-SPS/U parallel robot, as shown in fig. 1, the first wrist joint 18 and the second wrist joint 19 form a structure similar to a universal joint, so that two rotation axes of the wrist intersect with each other and are matched with the bracket 25, the wrist joint has basic pitching and deflecting functions, and for each movement, two motors can play roles, and compared with other wrist mechanisms with two degrees of freedom in series, the wrist joint realizing mechanism can provide larger bearing capacity. Each SPS branched chain uses the linear driver of the first part, the method can be placed in the forearm, and meanwhile, the linear guide rail part is arranged downwards, so that the structure is compact, and the space is fully utilized; through calculation, interference hardly occurs between the two branched chains in the required working space, so that the space between the two branched chains is provided with a utilization value, and a larger working space is ensured; the tracks are arranged in the rack 25 as shown by the curve in fig. 1. The position between two branched chains on the shell 3 is opened, so that the wiring of the control motor can be relatively centralized, and the coordination control is convenient; the wiring of the subsequent manipulator can be arranged in the opening in the middle of the wrist joint and the hollow through hole of the palm connector 20, so that the universal use is wide, and most wiring requirements can be met. The whole wiring is outside the linear driver, so that the driving of the mechanism is not influenced, interference with the wrist mechanism is hardly generated, and the working space is indirectly enlarged.

The method comprises the following steps: as shown in fig. 1, a robot wrist joint includes a first wrist joint 18, a second wrist joint 19, a palm connector 20, a bracket 25, and two linear drivers; the first wrist joint 18 and the second wrist joint 19 form a universal joint structure, the structure and the connection mode of the universal joint structure are the same as those of the existing robot wrist joint, the first wrist joint 18 and the second wrist joint 19 are arranged on the bracket 25 and are connected with the palm connector 20, one ends of the two linear drivers are hinged with the palm connector 20, so that the wrist joint has pitching and deflecting functions, and the other ends of the two linear drivers are connected with the bracket 25.

As shown in fig. 1 to 3, fish-eye spherical hinges 1 are respectively added at two ends of the linear driver, so that the connection between the movable joint and other joints of the robot is realized.

As shown in fig. 1 and 2, the linear driver comprises a frameless motor, a screw rod 5 and a linear guide rail; the frameless motor drives the screw rod 5 to rotate through the connecting piece, the linear guide rail is arranged on the outer side of the frameless motor, and the sliding block 8 arranged on the linear guide rail is fixedly connected with the screw rod 5 through the connecting rod 6, so that the conversion from rotary motion to linear motion is realized.

As shown in fig. 1 and 2, the frameless motor includes a housing 3, a stator 9, a rotor 10, a first connecting member 11, a second connecting member 12, a nut 13, and a PCB 14; the shell 3 is coaxially arranged with the first connecting piece 11 and the second connecting piece 12, the first connecting piece 11 and the second connecting piece 12 are fixedly connected, the stator 9 and the rotor 10 are respectively fixed at corresponding positions of the shell 3 and the first connecting piece 11, the second connecting piece 12, the nut 13 and the screw rod 5 are coaxially arranged from outside to inside, the second connecting piece 12 is fixedly connected with the nut 13, the screw rod 5 is in threaded connection with the nut 13, the outer end of the screw rod 5 is fixedly connected with one end of the connecting rod 6, and the PCB 14 is arranged in the shell 3 and can drive the stator 9 to rotate.

As shown in fig. 1 and 2, the linear guide rail comprises a guide rail 7 and a slide block 8; the other end of the connecting rod 6 is fixedly connected with a sliding block 8 through a screw, the sliding block 8 is in sliding connection with a guide rail 7, and the guide rail 7 is fixed on the outer surface of the shell 3.

As shown in fig. 1 and 2, a code disc 17 is arranged in a free space at the bottom of the shell 3, the code disc 17 is integrated on a connecting cover 21, and is fixed in the shell 3 through the connecting cover 21 and used for monitoring the rotating speed data of the frameless motor; the double encoders 15 are arranged in grooves on the outer surface of the shell 3, and the double encoders 15 and force sensors integrated on the bottom cover 2 are connected with a frameless motor, so that the force control and flexible control functions and motor end control are realized.

As shown in fig. 1 and 2, a boss is provided in the housing 3 to position the stator, and then the stator is fixed by a set screw;

the left side of the first connecting piece 11 is limited by a third bearing 22, a connecting cover 21 and a bottom cover 2, and the right side of the first connecting piece is limited by a second connecting piece 12; the left side of the second connecting piece 12 is limited by a first bearing 23 and a boss of the shell 3, and the right side is limited by a second bearing 24 and a top cover 4.

As shown in fig. 1 and 2, two spherical hinges 1 are respectively installed on the outer end of the bottom cover 2 and the outer end of the screw rod 5.

The working principle of the linear driving is as follows: inputting a control signal to a PCB (printed circuit board) 14 of the motor through an opening on the shell, driving a rotor 10 to rotate, driving a connecting piece I11 to rotate by the rotor 10, driving a connecting piece II 12 to rotate by the connecting piece I11, and driving a nut 13 to rotate by the connecting piece II 12, so that a screw rod 5 has a tendency of rotating motion; the screw rod 5 is fixedly connected with the linear guide rail through the connecting rod 6 to prevent the screw rod from rotating, so that the movement of the screw rod is changed into linear movement, and a fixed direction is provided for the linear movement, thereby realizing a linear driving function.

The frameless motor adopted by the scheme has small occupied space and high designability, and meanwhile, the function of a speed reducer is replaced by the high transmission ratio of the screw nut structure, so that the occupied space of the mechanism is further reduced; the design of arranging the sensor in the gap between the connecting cover and the bottom cover and in the groove at the top of the shell fully utilizes the space, reduces the required volume of the mechanism, completely realizes the sensing requirement of the mechanism, gives the advantage of full sensing to the joint and does not influence the work of the linear driver; meanwhile, when the required moment is larger, linear guide rails can be added at the left end and the right end of the shell to meet the requirement, so that the design freedom degree is high; the spherical hinge with a certain length of rod length is used for the bottom cover and the connecting rod, so that the integral part of the mechanism is far away from the connecting parts at two ends, and interference between the linear driver and the structures at two sides is avoided.

It will be understood that the invention has been described in terms of several embodiments, and that various changes and equivalents may be made to these features and embodiments by those skilled in the art without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. The robot wrist joint is characterized in that: comprises a first wrist joint (18), a second wrist joint (19), a palm connector (20), a bracket (25) and two linear drivers; the wrist joint I (18) and the wrist joint II (19) form a universal joint structure, the wrist joint I (18) and the wrist joint II (19) are arranged on the bracket (25) and are connected with the palm connector (20), one ends of the two linear drivers are hinged with the palm connector (20), so that the wrist joint has pitching and deflecting functions, and the other ends of the two linear drivers are connected with the bracket (25).

2. A robotic wrist as claimed in claim 1, wherein: ball hinges (1) are additionally arranged at two ends of the linear driver respectively, so that connection between the movable joint and other joints of the robot is realized.

3. A robotic wrist as claimed in claim 2, wherein: the linear driver comprises a frameless motor, a lead screw (5) and a linear guide rail; the frameless motor drives the screw rod (5) to rotate through the connecting piece, the linear guide rail is arranged on the outer side of the frameless motor, and the sliding block (8) arranged on the linear guide rail is fixedly connected with the screw rod (5) through the connecting rod (6), so that the conversion from rotary motion to linear motion is realized.

4. A robotic wrist according to claim 3, wherein: the frameless motor comprises a shell (3), a stator (9), a rotor (10), a first connecting piece (11), a second connecting piece (12), a nut (13) and a PCB (14); the shell (3) is coaxially arranged with the first connecting piece (11) and the second connecting piece (12), the first connecting piece (11) and the second connecting piece (12) are fixedly connected, the stator (9) and the rotor (10) are respectively fixed at corresponding positions of the shell (3) and the first connecting piece (11), the second connecting piece (12), the nut (13) and the screw rod (5) are coaxially arranged from outside to inside, the second connecting piece (12) is fixedly connected with the nut (13), the screw rod (5) is in threaded connection with the nut (13), the outer end of the screw rod (5) is fixedly connected with one end of the connecting rod (6), and the PCB (14) is arranged in the shell (3) and can drive the stator (9) to rotate.

5. The robotic wrist according to claim 4, wherein: the linear guide rail comprises a guide rail (7) and a sliding block (8); the other end of the connecting rod (6) is fixedly connected with a sliding block (8), the sliding block (8) is in sliding connection with a guide rail (7), and the guide rail (7) is fixed on the outer surface of the shell (3).

6. A robotic wrist according to claim 5, wherein: a code disc (17) is arranged in a free space at the bottom of the shell (3), the code disc (17) is integrated on a connecting cover (21), and is fixed in the shell (3) through the connecting cover (21) and used for monitoring rotating speed data of the frameless motor; the double encoders (15) are arranged in grooves on the outer surface of the shell (3), and the double encoders (15) and the force sensor integrated on the bottom cover (2) are connected with a frameless motor to realize force control and flexible control functions and motor end control.

7. The robotic wrist of claim 6, wherein: the left side of the first connecting piece (11) is limited by a third bearing (22), a connecting cover (21) and a bottom cover (2), and the right side of the first connecting piece is limited by a second connecting piece (12); the left side of the second connecting piece (12) is limited with a boss of the shell (3) through a first bearing (23), and the right side is limited with the top cover (4) through a second bearing (24).

8. The robotic wrist of claim 7, wherein: the two spherical hinges (1) are respectively arranged at the outer ends of the bottom cover (2) and the screw rod (5).