A robot wrist joint

Abstract

A robot wrist joint belongs to the field of robot technology. Wrist joint 1 and wrist joint 2 form a universal joint structure, which are mounted on a bracket and connected to a palm connector. One end of two linear actuators are hinged to the palm connector, so that the wrist joint has pitch and deflection functions, and the other ends of the two linear actuators are connected to the bracket. The sensor design of the present invention is highly integrated with the mechanical structure, and the arrangement of the free space is used to make the mechanism have the advantages of small size and full perception: the dual encoder structure can realize high-precision position control, and the force sensor can realize force control and compliance control functions and motor end control. The proposed force sensor structure integrated into the fixed housing is buried in the housing structure and integrated with the linear guide rail, which is simpler and more convenient, smaller in size, and better in rigidity; the code disk structure is integrated in the bottom cover, which is compact and easy to install.

Description

Technical Field

[0001] The invention belongs to the technical field of robots, and in particular relates to a robot wrist joint. Background Art

[0002] The robot wrist mechanism is an important part of the robot, responsible for controlling the posture and position of the robot's end effector. In some cases, a flexible wrist is easier to achieve specific functions than a flexible hand. Therefore, the design of the wrist is very important in the design of the manipulator. In the current design of two-degree-of-freedom wrist joints, the series type inevitably requires the use of an additional reducer, which occupies a large space and has a bloated structure. Only a few (such as the bevel gear differential solution and the tendon solution) have the characteristics of coupling two degrees of freedom; most parallel types use spherical parallel mechanisms. Due to the complex structure, interference between parts is easy to occur, and the working space is difficult to guarantee.

[0003] In the current design of mobile joints, some solutions use pneumatic or hydraulic cylinder solutions, which have problems such as overly complicated mechanisms, large volume, and prone to leakage; some solutions use planetary ball screw solutions, which have problems such as high cost and inconvenient assembly; at the same time, the volume occupied by the motor is also a problem that must be considered. Most designs are directed at how to arrange the placement of the reducer to minimize its volume, and it is difficult to design such a reducer with hollow wiring; since integrating force sensors in modular joints usually greatly reduces the joint stiffness and makes the structure very complicated, many modular joints do not integrate force sensors, and rarely use dual encoders, which cannot achieve control of the joint torque. Summary of the invention

[0004] In order to solve the above problems, the present invention further provides a robot wrist joint.

[0005] The technical solution adopted by the present invention is:

[0006] A robot wrist joint comprises a wrist joint 1, a wrist joint 2, a palm connector, a bracket and two linear actuators; the wrist joint 1 and the wrist joint 2 constitute a universal joint structure, the wrist joint 1 and the wrist joint 2 are mounted on the bracket and connected to the palm connector, one end of the two linear actuators are hinged to the palm connector so that the wrist joint has pitch and yaw functions, and the other ends of the two linear actuators are connected to the bracket.

[0007] Compared with the prior art, the present invention has the following beneficial effects:

[0008] 1. While completing the wrist function, the present invention has the advantages of simple structure, large load-bearing capacity, high efficiency, high precision, small size and light weight, etc. It is easy to route, does not occupy joint space, does not interfere with the joint mechanism, and is easy to integrate into the robot. The frameless torque motor is integrated with the driver, sensor and other circuits, and the structure is compact.

[0009] 2. The present invention solves the problems of economy and versatility of the robot's mobile joints, and integrates the reducer with the motion conversion function, greatly reducing the volume required for the mechanism, realizing the linear drive function with the smallest occupied space volume and high motion accuracy.

[0010] 3. The sensor design of the present invention is highly integrated with the mechanical structure, and the arrangement of the free space makes the mechanism have the advantages of small size and full perception: the dual encoder structure can achieve high-precision position control, and the force sensor can realize force control and compliance control functions and motor end control. The proposed dual encoder structure integrated into the fixed housing is buried in the housing structure and integrated with the linear guide, which is simpler and more convenient, with smaller size and better rigidity; the torque sensor and the code disk structure are integrated in the bottom cover, which has a compact structure and is easy to install.

[0011] 4. The linear drive that converts rotational motion into linear motion in the present invention is a major feature of the present design. The linear drive used in the present invention has the advantages of high precision, compact structure, highly integrated sensors, and full perception, and eliminates the structure of the reducer, occupies a small volume, and is convenient for direct use.

[0012] 5. The present invention has good economical efficiency and uses relatively common parts to achieve its functions; it has a simple structure and complete functions, and utilizes the free space of the structure to integrate very important sensors without affecting the overall structure and joint stiffness, and has good versatility; the wrist mechanism has a complete structure and full functions, and can provide a large torque compared to other wrist mechanisms. At the same time, the wiring is concentrated in a position that does not interfere with the structure, thereby expanding the working space and facilitating overall control. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is an isometric view of the present invention;

[0014] Figure 2 is an isometric view of the linear actuator of the present invention;

[0015] Figure 3 is a main sectional view of the linear actuator of the present invention;

[0016] Among them: 1. ball joint; 2. bottom cover; 3. outer shell; 4. top cover; 5. lead screw; 6. connecting rod; 7. guide rail; 8. slider; 9. stator; 10. rotor; 11. connector 1; 12. connector 2; 13. nut; 14. PCB board; 15. dual encoder; 16. beam; 17. code disk; 18. wrist joint 1; 19. wrist joint 2; 20. palm connector; 21. connecting cover; 22. bearing 3; 23. bearing 1; 24. bearing 2; 25. bracket. DETAILED DESCRIPTION

[0017] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings.

[0018] like Figure 1 to Figure 3 As shown, the robot mobile joint of the present invention includes two parts: one part is a linear driver for realizing a linear driving function, in which sensors are integrated; and the other part is a wrist joint realization mechanism.

[0019] The first part of the linear drive uses a frameless motor as the power source, uses the combination of a lead screw and a linear guide to achieve the conversion from rotational motion to linear motion, and cooperates with various connecting parts to form a linear drive; fisheye ball joints are installed at both ends of the linear drive to achieve the connection between the mobile joint and other joints of the robot. At the same time, a free space is reserved at the bottom of the linear drive to install the code disk to detect the speed of the motor; a dual encoder is installed in the top boss, and the torque sensor is integrated into the bottom cover 2, making the structure simpler, smaller in size, and better in rigidity; the integration of the sensor utilizes the free space in the structural design, the structure is simple, does not occupy additional volume, makes the structure more compact, and does not affect the joint rigidity. Among them, the main parts, the frameless motor and the ball screw, have the advantages of small volume, good economy, and high motion accuracy. The ball pair provided by the fisheye ball joint can well meet the various degrees of freedom required at both ends, and has the advantage of good generalization.

[0020] The wrist joint of the second part is realized by a 2-SPS / U parallel robot. Figure 1As shown, wrist joint 18 and wrist joint 2 19 form a structure similar to a universal joint, so that the two rotational axes of the wrist intersect, and cooperate with the bracket 25, so that the wrist joint has basic pitch and yaw functions, and for each movement, the two motors can play a role, compared with the other serial two-degree-of-freedom wrist mechanisms, it can provide a larger load-bearing capacity. Each SPS branch chain uses the linear drive described in the first part. This method can be placed in the forearm, and the linear guide part is placed downward, which has a compact structure and fully utilizes the space. After calculation, within the required working space, there is almost no interference between the two branches, which provides utilization value for the space between the two branches and ensures a relatively large working space. Arrange the wiring in the bracket 25, such as Figure 1 As shown by the middle curve. The position between the two chains on the housing 3 is opened, so that the wiring of the control motor can be relatively concentrated, which is convenient for coordinated control; the wiring of the subsequent manipulator can also be arranged in the opening in the middle of the wrist joint and the hollow through hole of the palm connector 20, which is versatile and can meet most wiring requirements. The overall wiring is outside the linear drive, does not affect the mechanism drive, and almost does not interfere with the wrist mechanism, which indirectly expands the working space.

[0021] Specifically: Figure 1 As shown, a robot wrist joint includes a wrist joint 18, a wrist joint 19, a palm connector 20, a bracket 25 and two linear actuators; the wrist joint 18 and the wrist joint 19 constitute a universal joint structure, and its structure and connection method are the same as those of the existing robot wrist joints. The wrist joint 18 and the wrist joint 19 are installed on the bracket 25 and connected to the palm connector 20. One end of the two linear actuators is hinged to the palm connector 20, so that the wrist joint has pitch and yaw functions, and the other end of the two linear actuators is connected to the bracket 25.

[0022] like Figures 1 to 3 As shown, fisheye ball joints 1 are installed at both ends of the linear actuator to achieve the connection between the moving joint and other joints of the robot.

[0023] like Figure 1 , Figure 2 As shown, the linear drive includes a frameless motor, a lead screw 5 and a linear guide; the frameless motor drives the lead screw 5 to rotate through a connecting piece, and the linear guide is arranged on the outside of the frameless motor. The slider 8 arranged on the linear guide is fixedly connected to the lead screw 5 through a connecting rod 6 to realize the conversion from rotational motion to linear motion.

[0024] like Figure 1 , Figure 2As shown, the frameless motor includes a housing 3, a stator 9, a rotor 10, a connector 11, a connector 2 12, a nut 13 and a PCB board 14; the housing 3 is coaxially arranged with the connector 1 11 and the connector 2 12, the connector 1 11 and the connector 2 12 are fixedly connected, the stator 9 and the rotor 10 are respectively fixed at corresponding positions of the housing 3 and the connector 1 11, the connector 2 12, the nut 13 and the lead screw 5 are coaxially arranged from outside to inside, the connector 2 12 is fixedly connected with the nut 13, the lead screw 5 is threadedly connected with the nut 13, the outer end of the lead screw 5 is fixedly connected with one end of the connecting rod 6, and the PCB board 14 is arranged in the housing 3 and can drive the stator 9 to rotate.

[0025] like Figure 1 , Figure 2 As shown, the linear guide includes a guide rail 7 and a slider 8; the other end of the connecting rod 6 is fixedly connected to the slider 8 by a screw, the slider 8 is slidably connected to the guide rail 7, and the guide rail 7 is fixed on the outer surface of the housing 3.

[0026] like Figure 1 , Figure 2 As shown, a code disk 17 is arranged in the free space at the bottom of the housing 3, and the code disk 17 is integrated on the connecting cover 21 and fixed in the housing 3 through the connecting cover 21, so as to monitor the speed data of the frameless motor; a dual encoder 15 is installed in the groove on the outer surface of the housing 3, and the dual encoder 15 and the force sensor integrated in the bottom cover 2 are connected to the frameless motor to realize force control and compliance control functions and motor end control.

[0027] like Figure 1 , Figure 2 As shown, a boss is provided in the housing 3 to position the stator, and then the stator is fixed by tightening screws;

[0028] The left side of the connecting member 11 is limited by the bearing 3 22, the connecting cover 21 and the bottom cover 2, and the right side is limited by the connecting member 2 12; the left side of the connecting member 2 12 is limited by the bearing 1 23 and the boss of the outer shell 3, and the right side is limited by the bearing 2 24 and the top cover 4.

[0029] like Figure 1 , Figure 2 As shown, the two ball joints 1 are respectively mounted on the outer end of the bottom cover 2 and the outer end of the lead screw 5.

[0030] The working principle of the linear drive is as follows: a control signal is input to the PCB board 14 of the motor through the opening on the shell to drive the rotor 10 to rotate, the rotor 10 drives the connecting piece 11 to rotate, the connecting piece 11 drives the connecting piece 2 12 to rotate, and the connecting piece 2 12 drives the nut 13 to rotate, so that the lead screw 5 has a tendency to rotate; and the lead screw 5 is fixedly connected to the linear guide rail through the connecting rod 6 to prevent it from rotating, so that its movement is converted into linear motion, and a fixed direction is provided for the linear motion, thereby realizing the linear drive function.

[0031] The frameless motor adopted in this solution occupies a small space and has a high degree of designability. At the same time, the high transmission ratio of the screw-nut structure replaces the function of the reducer, further reducing the space occupied by the mechanism; the design of placing sensors in the gap between the connecting cover and the bottom cover and in the groove on the top of the shell makes full use of the space, reduces the volume required for the mechanism, and fully realizes the sensing needs of the mechanism, giving the joint the advantage of full perception without affecting the operation of the linear drive; at the same time, when the required torque is large, linear guides can be added to the left and right ends of the shell to meet the needs, with a high degree of design freedom; ball joints with a certain length of rod are used on the bottom cover and the connecting rod, so that the overall part of the mechanism is away from the connecting parts at both ends, avoiding interference between the linear drive and the structures on both sides.

[0032] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A robot wrist joint, characterized in that: The invention comprises a wrist joint 1 (18), a wrist joint 2 (19), a palm connector (20), a bracket (25) and two linear drives; the linear drive comprises a frameless motor, a lead screw (5) and a linear guide rail; the frameless motor comprises a housing (3), a stator (9), a rotor (10), a connector 1 (11), a connector 2 (12), a nut (13) and a PCB board (14); the wrist joint 1 (18) and the wrist joint 2 (19) form a universal joint structure; the wrist joint 1 (18) and the wrist joint 2 (19) are mounted on the bracket (25) and connected to the palm connector (20); one end of the two linear drives are hinged to the palm connector (20) so that the wrist joint has pitch and yaw functions; the other ends of the two linear drives are connected to the bracket (25); a code disk (17) is arranged in the free space at the bottom of the housing (3); the code disk (17) is integrated on a connection cover (21) and is connected to the connection cover via the connection cover. (21) is fixed in the housing (3) and is used to monitor the speed data of the frameless motor; a dual encoder (15) is installed in a groove on the outer surface of the housing (3), and the dual encoder (15) and the force sensor integrated in the bottom cover (2) are connected to the frameless motor to realize force control and compliance control functions and motor end control. The housing (3) is coaxially arranged with the connecting piece 1 (11) and the connecting piece 2 (12), and the connecting piece 1 (11) and the connecting piece 2 (12) are fixedly connected. The stator (9) and the rotor (10) are fixed to corresponding positions of the housing (3) and the first connecting member (11), respectively; the second connecting member (12), the nut (13) and the lead screw (5) are coaxially arranged from outside to inside; the second connecting member (12) is fixedly connected to the nut (13); the lead screw (5) is threadedly connected to the nut (13); the outer end of the lead screw (5) is fixedly connected to one end of the connecting rod (6); and the PCB board (14) is arranged in the housing (3) and is capable of driving the stator (9) to rotate.

2. A robot wrist joint according to claim 1, characterized in that: Ball joints (1) are respectively installed at both ends of the linear drive to achieve the connection between the moving joint and other joints of the robot.

3. A robot wrist joint according to claim 2, characterized in that: The frameless motor drives the lead screw (5) to rotate via a connecting piece, the linear guide rail is arranged outside the frameless motor, and a slider (8) arranged on the linear guide rail is fixedly connected to the lead screw (5) via a connecting rod (6), thereby realizing the conversion from rotational motion to linear motion.

4. A robot wrist joint according to claim 3, characterized in that: The linear guide comprises a guide rail (7) and a slider (8); the other end of the connecting rod (6) is fixedly connected to the slider (8); the slider (8) is slidably connected to the guide rail (7); and the guide rail (7) is fixed to the outer surface of the housing (3).

5. A robot wrist joint according to claim 4, characterized in that: The left side of the connecting member 1 (11) is limited by the bearing 3 (22), the connecting cover (21) and the bottom cover (2), and the right side is limited by the connecting member 2 (12); the left side of the connecting member 2 (12) is limited by the bearing 1 (23) and the boss of the housing (3), and the right side is limited by the bearing 2 (24) and the top cover (4).

6. A robot wrist joint according to claim 5, characterized in that: The two ball joints (1) are respectively mounted on the outer end of the bottom cover (2) and the outer end of the lead screw (5).

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