CN117584169A - A robot wrist joint - Google Patents

Abstract

A kind of robot wrist joint belongs to the field of robot technology. Wrist Shutdown 1 and Wrist Joint 2 form a universal joint structure. Wrist Shutdown 1 and Wrist Joint 2 are installed on the bracket and connected to the palm connector. One end of the two linear actuators is hinged to the palm connector, allowing the wrist joints to have pitch and deflection. Function, 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 allows the mechanism to have the advantages of small size and full perception: it has a dual encoder structure to achieve high-precision position control, and a force sensor to achieve force control and compliance control. Function and motor end control, the proposed force sensor structure integrated into the fixed shell is buried in the shell structure and integrated with the linear guide rail, which is simpler and more convenient, smaller in size and better in stiffness; the code disk structure is integrated in the bottom cover, the structure Compact and easy to install.

Description

A robot wrist joint

Technical field

The invention belongs to the field of robot technology, and specifically relates to a robot wrist joint.

Background technique

The robot wrist mechanism is an important part of the robot and is responsible for controlling the attitude and position of the robot's end effector. In some cases, a flexible wrist is easier to achieve a specific function 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 uses an additional reducer, which takes up a lot of space and has a bloated structure, and only a few (such as the bevel gear differential scheme and the tendon scheme) have two-freedom coupling. Characteristics of high degree of accuracy; most designs of 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.

In the current design of mobile joints, some solutions use pneumatic cylinders or hydraulic cylinders that have problems such as too complicated mechanisms, occupying a large volume, and are prone to leakage; some solutions use planetary ball screw solutions that are too costly and inconvenient to assemble. and other issues; at the same time, the volume occupied by the motor is also an issue that has to be considered. Most designs focus on how to arrange the placement of the reducer so that it occupies the smallest volume, and it is difficult to design hollow wiring for such a reducer; due to the modular joint Integrating force sensors usually greatly reduces joint stiffness and makes the structure very complex. Many modular joints do not integrate force sensors and rarely use dual encoders, which cannot control joint torque.

Contents of the invention

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

The technical solutions adopted by the present invention are:

A kind of robot wrist joint, including wrist joint one, wrist joint two, palm connector, bracket and two linear drives; the wrist joint one and wrist joint two constitute a universal joint structure, and the wrist joint one and wrist joint two are installed on On the bracket and connected to the palm connector, one end of the two linear actuators is hinged to the palm connector, so that the wrist joint has pitch and deflection functions, and the other end of the two linear actuators is connected to the bracket.

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

1. While completing the function of the wrist, the present invention has the advantages of simple structure, large load-bearing capacity, high efficiency, high precision, small size and lightweight. It is convenient for routing, does not occupy joint space, does not interfere with the joint mechanism, and is convenient. integrated into the robot. The frameless torque motor is integrated with circuits such as drivers and sensors to achieve a compact structure.

2. The present invention solves the problems of economy and versatility of robot moving joints. At the same time, it integrates the reducer and motion conversion function, greatly reduces the required volume of the mechanism, and realizes linear drive with the smallest occupied space. Function, high movement precision.

3. The sensor design of the present invention is highly integrated with the mechanical structure, and the arrangement of the free space enables the mechanism to have the advantages of small size and full perception: it has a dual encoder structure to achieve high-precision position control, and a force sensor to achieve force control and Compliance control function and motor-side control, the proposed dual encoder 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 stiffness; a torque sensor is integrated in the bottom cover And code plate structure, compact structure, easy to install.

4. The linear actuator that converts rotational motion into linear motion is a major feature of this design. The linear actuator used in this invention has the advantages of high precision, compact mechanism, highly integrated sensors, and full sensing, and eliminates the need for deceleration. The structure of the device occupies a small volume and is convenient for direct use.

5. The invention is economical and uses relatively common parts to realize its functions; it has a simple structure and complete functions at the same time. It uses 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 complete functions. Compared with other wrist mechanisms, it can provide a larger torque. At the same time, the wiring is concentrated in a position that does not interfere with the structure, which expands the work space and facilitates overall control.

Description of drawings

Figure 1 is an isometric view of the present invention;

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

Figure 3 is a main cross-sectional view of the linear actuator of the present invention;

Among them: 1. Ball hinge; 2. Bottom cover; 3. Shell; 4. Top cover; 5. Lead screw; 6. Connecting rod; 7. Guide rail; 8. Slider; 9. Stator; 10. Rotor; 11. Connector one; 12, connector two; 13, nut; 14, PCB board; 15, double encoder; 16, beam; 17, code plate; 18, wrist joint one; 19, wrist joint two; 20, palm connection device; 21. Connection cover; 22. Bearing three; 23. Bearing one; 24. Bearing two; 25. Bracket.

Detailed ways

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

As shown in Figures 1 to 3, the robot mobile joint of the present invention consists of two parts: one part is a linear driver that realizes the linear drive function, and the sensor is integrated in the linear driver part; the other part is the wrist joint implementation mechanism.

The first part of the linear drive uses a frameless motor as the power source. It uses the cooperation of the screw and the linear guide rail to realize the conversion of rotary motion to linear motion. It cooperates with various connecting parts to form a linear drive; fish eyes are installed at both ends of the linear drive. Hinge to realize the connection between the mobile joint and other joints of the robot. At the same time, free space is left at the bottom of the linear drive to install the code disk and detect the rotation speed of the motor; dual encoders are 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 sensors takes advantage of the free space in the structural design. The structure is simple and does not occupy additional volume, making the structure more compact without affecting joint stiffness. Among them, the main parts, the frameless motor and the ball screw, have the advantages of small size, good economy, and high movement accuracy. The ball pair provided by the fish eye hinge can well meet the various degrees of freedom required at both ends. It has the advantage of good generalization.

The second part of the wrist joint implementation mechanism is a 2-SPS/U parallel robot. As shown in Figure 1, wrist joint one 18 and wrist joint two 19 form a universal joint-like structure, allowing the two wrists to rotate freely. The degree axes intersect and cooperate with the bracket 25 so that the wrist joint has basic pitch and deflection functions, and for each movement, the two motors can play a role. Compared with other series two-degree-of-freedom wrist mechanisms, it can provide more Large carrying capacity. Each SPS branch chain uses the linear drive described in the first part. This method can be placed in the forearm while placing the linear guide part downward. The structure is compact and makes full use of space; after calculation, within the required working space , there is almost no interference between the two branch chains, which provides utilization value for the space between the two chains and ensures a relatively large working space; arrange the wiring in the bracket 25, as shown in the curve in Figure 1 . 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 facilitates coordinated control; the wiring of the subsequent manipulator can also be arranged in the opening in the middle of the wrist joint and the palm connector 20 The hollow through hole has wide versatility and can meet most wiring needs. The overall wiring is outside the linear driver, which does not affect the mechanism drive and hardly interferes with the wrist mechanism, which indirectly expands the working space.

Specifically: as shown in Figure 1, a robot wrist joint includes a wrist joint 18, a wrist joint 2 19, a palm connector 20, a bracket 25 and two linear actuators; the wrist joint 18, the wrist joint 2 19 It forms a universal joint structure, and its structure and connection method are the same as those of existing robot wrist joints. Wrist joint one 18 and wrist joint two 19 are installed on the bracket 25 and connected to the palm connector 20. One end of the two linear actuators is connected to the palm. The connector 20 is hinged so that the wrist joint has pitch and deflection functions, and the other ends of the two linear actuators are connected to the bracket 25 .

As shown in Figures 1 to 3, fish eye hinges 1 are installed at both ends of the linear actuator to realize the connection between the mobile joint and other joints of the robot.

As shown in Figures 1 and 2, the linear drive includes a frameless motor, a lead screw 5 and a linear guide rail; the frameless motor drives the lead screw 5 to rotate through a connector, and the linear guide rail is arranged outside the frameless motor. The slider 8 provided on the linear guide rail and the screw 5 are fixedly connected through a connecting rod 6 to realize the conversion from rotary motion to linear motion.

As shown in Figures 1 and 2, the frameless motor includes a casing 3, a stator 9, a rotor 10, a connecting piece 11, a connecting piece 2 12, a nut 13 and a PCB board 14; the casing 3 and the connecting piece 11 Coaxially arranged with the second connector 12, the first connector 11 and the second connector 12 are fixedly connected. The stator 9 and the rotor 10 are respectively fixed at the corresponding positions of the housing 3 and the connector one 11. The second connector 12 , nut 13 and screw 5 are arranged coaxially from outside to inside, connector 2 12 is fixedly connected to nut 13, screw 5 is threadedly connected to nut 13, the outer end of screw 5 is fixedly connected to one end of connecting rod 6, the PCB The plate 14 is arranged inside the housing 3 and is able to drive the stator 9 to rotate.

As shown in Figures 1 and 2, the linear guide rail includes a guide rail 7 and a slider 8; the other end of the connecting rod 6 is fixedly connected to the slider 8 through screws, and the slider 8 is slidingly connected to the guide rail 7. The guide rail 7 is fixed on the outer surface of the housing 3 .

As shown in Figures 1 and 2, a code disk 17 is provided in the free space at the bottom of the housing 3. The code disk 17 is integrated on the connecting cover 21 and is fixed in the housing 3 through the connecting cover 21 for monitoring the frameless motor. Speed data; dual encoders 15 are installed in the grooves on the outer surface of the housing 3. The dual encoders 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.

As shown in Figures 1 and 2, a boss is provided in the housing 3 to position the stator, and the stator is fixed by tightening screws;

The left side of the connector one 11 is limited by the bearing three 22, the connecting cover 21 and the bottom cover 2, and the right side is limited by the connector two 12; the left side of the connector two 12 is limited by the boss of the bearing one 23 and the shell 3, and the right side is limited by the boss of the bearing one 23 and the shell 3. The position is limited by bearing 24 and top cover 4.

As shown in Figures 1 and 2, the two ball hinges 1 are installed on the outer end of the bottom cover 2 and the outer end of the lead screw 5 respectively.

The working principle of the linear drive is: input a control signal to the PCB board 14 of the motor through the opening on the casing 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, causing the screw 5 to have a tendency to rotate; and the screw 5 is firmly connected to the linear guide rail through the connecting rod 6, preventing its rotation, turning its motion into linear motion, and providing a fixed direction for the linear motion. Realize linear drive function.

The frameless motor used in this solution occupies a small space and can be designed to a high degree. 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; when connecting the cover and the bottom cover The design of placing the sensor in the gap and the groove on the top of the shell makes full use of the space, reduces the required volume of the mechanism, completely realizes the sensing needs of the mechanism, and gives the joints the advantage of full sensing without affecting the straight line. The driver works; at the same time, when the required torque is large, linear guides can also be added to the left and right ends of the housing to meet the needs, with a high degree of design freedom; a ball hinge with a certain length of rod is used on the bottom cover and connecting rod to make the overall mechanism The part is far away from the connecting parts at both ends to avoid interference between the linear actuator and the structures on both sides.

It is understood that the present invention has been described through some embodiments. Those skilled in the art know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, the features and embodiments may be modified to adapt a particular situation and material to the teachings of the invention without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed here, and all embodiments falling within the scope of the claims of the present application are within the scope of protection of the present invention.

Claims (8)

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).