A linear joint of "motor-nut-bearing" integrated design

Abstract

The application discloses a linear joint with integrated design of motor-nut-bearing, which is suitable for operation requirements and motion accuracy of humanoid robots. The linear joint is designed with integrated design of motor rotor-reverse screw nut-bearing, the motor rotor magnet is pasted on the nut outer circle of the reverse screw, the symmetric double screw reinforcing structure is used for fixation, the nut outer circle is designed as the inner ring of the angular contact ball bearing, the structure is more compact, and high integration, high performance, high precision, high dynamic response and high power density of the linear joint are further realized. The reverse screw pair is used for converting the rotary motion of the nut into the linear motion of the screw, and a mechanical zero point is arranged on the encoder side, so that the linear joint has the limiting function. The linear joint is provided with the absolute value type encoder and the tension and pressure sensor, so that the rotation speed, displacement and tension and pressure in the actual motion process can be monitored in real time.

Description

Technical Field

[0001] This invention belongs to the fields of precision transmission technology, transmission devices and humanoid robots, and in particular, a linear joint with an integrated design of "motor-nut-bearing". Background Technology

[0002] Humanoid robots can adapt to human working environments, mimic human behavior, facilitate the generation and control of multimodal interaction commands, and are more adaptable to work objects, environments, and tasks, making them more versatile and intelligent. Humanoid robots are not only a future industry, but also the culmination of future industries, and a focal point of great power competition. In the future, humanoid robots are expected to replace humans in logistics, household services, industrial inspections, cleaning, and other operations within human work environments. They may even perform tasks in dangerous environments such as the wilderness and outer space.

[0003] This research focuses on "mechanical brain, mechanical body, and mechanical limbs," aiming to empower humanoid robots with embodied intelligence and develop related technologies to enhance their physical capabilities, skills, and intelligence. Among these, the "mechanical limbs" of humanoid robots primarily consist of dexterous hands, rotary joints, and linear joints. Linear joints are used in the wrists, arms, and legs of humanoid robots to achieve high-speed transmission and control at high rotational speeds, requiring performance characteristics such as short-term high load-bearing capacity, high precision, and high dynamic response.

[0004] Existing linear joints in humanoid robots mostly have short strokes and long overall bodies, making them unsuitable for the space constraints of humanoid robot joints. Simultaneously, there is a requirement for highly integrated, high-performance, high-precision, and high-dynamic-response linear joints. Therefore, it is necessary to design a humanoid robot linear joint based on a reverse-actuated lead screw, which can meet the operational requirements and motion accuracy of humanoid robots. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies, such as the long axial length which cannot adequately accommodate the space constraints of humanoid robot joints, and the poor temperature rise and noise conditions caused by small lead-point, high-speed rotation. This invention proposes a linear joint design for humanoid robots based on a reverse-type lead screw pair, which better meets the operational requirements and motion accuracy of humanoid robots. The integrated design of "motor rotor-reverse lead screw nut-bearing" results in a more compact structure, further achieving high integration, high performance, high precision, high dynamic response, and high power density of the linear joint.

[0006] The technical solution to achieve the purpose of this invention is: a linear joint with an integrated design of "motor-nut-bearing", wherein the entire linear joint adopts an integrated design of "motor-nut-bearing", including a motor unit, a transmission unit, a housing unit and a sensing unit;

[0007] The motor unit is used to convert electrical energy into rotational kinetic energy of the motor rotor;

[0008] The transmission unit converts the rotational motion of the nut into the linear motion of the screw through a reverse lead screw pair, and transmits the axial load to the housing through the lead screw pair and bearing assembly.

[0009] The outer shell unit is used to bear the final load, while also protecting the internal structure, providing a seal, and providing mounting positions for the self-lubricating radial joint bearings at both ends of the linear joint.

[0010] The sensing unit is used to detect the rotational speed, displacement, and tensile and compressive forces acting on the linear joint during operation.

[0011] Furthermore, the motor unit adopts an integrated design combining a reverse-type lead screw pair nut and a motor rotor, with the motor rotor bonded to the outer circle of the nut, directly driving the nut to rotate; the lead screw pair adopts a large lead design, and a symmetrical double-helix force-increasing structure is designed on the outer circle of the nut, with symmetrical double-helix force-increasing grooves set on the outer circle respectively, and the parametric equation of the right helix is:

[0012]

[0013] Where θ = ωt, ω is the angular velocity, b = p / 2π = acotβ, β is the helix angle, p is the pitch; x and y are the coordinates of the helix projected onto the xoy plane, a is the radius of the cylinder encircled by the helix, and z is the height of the point on the helix;

[0014] The symmetrical double-helix force-increasing groove is used to minimize the impact on the dynamic balance of the nut. At the same time, after the adhesive bonding the rotor magnet has cured, it provides a radial anti-detachment force to the rotor magnet during rotation, so as to prevent the rotor magnet from detaching from the outer circle of the nut during rotation and ensure the fit of the rotor magnet.

[0015] Furthermore, the transmission unit adopts an integrated design combining a reverse lead screw pair nut and an angular contact ball bearing inner ring. For the long nut structure, a high power density and high thrust offset angular contact ball bearing is designed, and the bearing raceway adopts a design with small adaptability, large contact angle, and large steel balls. The outer circle of the nut is directly used as the inner ring of the angular contact ball bearing, and a large contact angle bearing raceway is machined on the outer circle of the nut.

[0016] Furthermore, in the transmission unit, the reverse lead screw pair adopts a design with a high-thrust bearing fixed end and a high-strength support end. The fixed end adopts an integrated angular contact ball bearing, and the support end adopts a deep groove ball bearing.

[0017] Furthermore, the deep groove ball bearing is fixed by using the step of the nut end cap and the elastic retaining ring of the shaft to fix the inner ring of the deep groove ball bearing and make the outer ring float, so as to adapt to the error caused by the different deformation of parts made of different materials when the temperature changes.

[0018] Furthermore, the transmission unit has a limiting function at one end of the reverse lead screw pair. By radially contacting the limiting screw with the same lead spiral step, it achieves the function of mechanical zero point, while avoiding the extreme situation where the starting torque increases or even cannot be disengaged due to the axial surface contact between the lead screw and the end cover.

[0019] Furthermore, the self-lubricating radial spherical bearings at both ends of the outer shell unit are fixed to the left and right bearing sleeves by a flanging and riveting process. The left bearing sleeve is threaded to the lead screw, and the right bearing sleeve is threaded to the tension and compression sensor.

[0020] Furthermore, both the left and right bearing sleeves are loosened by radial threads of concave-end set screws.

[0021] Furthermore, the sensing unit includes an encoder and a tension / compression sensor. The encoder is built into the linear joint, and one end of the tension / compression sensor is threadedly connected to the rear end cover of the housing unit, and the other end is threadedly connected to the right bearing sleeve, so as to realize the measurement of the tension and compression force on the linear joint during operation.

[0022] Furthermore, the encoder has its encoder magnetic sheet glued to the nut end cover, and the encoder PCB board is connected and installed on the rear end cover. The encoder magnetic sheet rotates together with the nut end cover and the nut of the lead screw pair, and the speed and displacement are measured directly through the rotation of the magnetic sheet.

[0023] Compared with the prior art, the significant advantages of this invention are:

[0024] (1) This invention integrates the motor rotor and the nut of the inverted lead screw into a single design, significantly reducing the axial dimension of the entire linear joint and effectively utilizing the long nut structure of the inverted lead screw. Compared to existing integrated design schemes, this invention features a special symmetrical double-helix guide groove structure on the outer surface of the nut of the inverted lead screw. Two threaded grooves symmetrical to the center of the nut's outer axis are machined on the outer surface of the nut. This provides an axial anti-disengagement force to the rotor magnet when the motor rotor drives the outer circle of the inverted lead screw nut to rotate, achieving smoother movement. Simultaneously, the centrally symmetrical structure does not disrupt the dynamic balance of the "nut-motor" connection, does not affect the motor's high-speed rotation, and facilitates high-speed transmission in the linear joint.

[0025] (2) The present invention integrates the inner ring of the angular contact ball bearing at the fixed end (left end) with the nut of the reverse lead screw, and directly processes the bearing raceway on the outer circle of the nut. Compared with the conventional structure, the axial locking mechanism of the bearing is eliminated, which effectively shortens the axial dimension of the linear joint machine, reduces the number of parts of the linear joint machine, effectively reduces the error coupling caused by installation and assembly, and ensures the overall installation accuracy and dynamic balance of the linear joint.

[0026] (3) The present invention has a mechanical limiting function at the end of the lead screw pair near the encoder, and at the same time, it acts as a mechanical zero point for incremental encoders, which facilitates the input and control of rotational speed. In addition, the limiting function is achieved by using the long screw of the end cover and the stepped surface of the lead screw pair. The limiting screw makes radial contact with the lead screw step, avoiding the extreme situation that the starting torque may increase or even fail to disengage due to the axial surface contact between the lead screw and the end cover, thus achieving an effective mechanical limiting function.

[0027] (4) The present invention uses a non-magnetic aluminum nut end cap to install the encoder magnetic sheet at the encoder end, which ensures the integrity of the magnetic lines of force of the encoder magnetic sheet and is conducive to the encoder to achieve accurate measurement; at the same time, the nut end cap is also used to fix the inner ring of the deep groove ball bearing, which is conducive to optimizing the process performance of the nut. The rotating body structure of the nut end cap will not affect the dynamic balance of the rotor and the nut as a whole.

[0028] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a linear joint structure with an integrated "motor-nut-bearing" design in one embodiment.

[0030] Figure 2 This is a top view of a linear joint in one embodiment, showing an integrated design of "motor-nut-bearing".

[0031] Figure 3 This is a left view of a linear joint in one embodiment, showing an integrated design of "motor-nut-bearing".

[0032] Figure 4 This is a right view of a linear joint in one embodiment, showing an integrated design of "motor-nut-bearing".

[0033] Figure 5 This is a schematic diagram of a symmetrical double-helix force-increasing structure of a nut in one embodiment.

[0034] Figure 6 This is a schematic diagram of the helix of a symmetrical double-helix force-increasing structure in one embodiment.

[0035] Figure 7 This is a schematic diagram of the lead screw pair limiting mechanism in one embodiment.

[0036] The figures in the attached diagram are labeled as follows: 1-Left bearing sleeve; 2-Self-lubricating radial spherical bearing 1; 3-Reverse lead screw pair lead screw; 4-Support guide sleeve; 5-Front end cover; 6-Bearing; 7-Reverse lead screw pair nut; 8-Housing; 9-Motor stator; 10-Motor rotor; 11-Limit screw; 12-Nut end cover; 13-Deep groove ball bearing; 14-Shaft retaining ring; 15-Encoder magnetic sheet; 16-Encoder PCB board; 17-Shim; 18-Tension / compression sensor; 19-Right bearing sleeve; 20-Self-lubricating radial spherical bearing 2; 21-Encoder cable outlet; 22-Rear end cover; 23-Motor cable outlet. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0039] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0040] Furthermore, if the embodiments of this invention involve descriptions of "springs," "screws," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined as "springs" or "screws" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention.

[0041] In one embodiment, the present invention provides a linear joint with an integrated "motor-nut-bearing" design. The linear joint as a whole adopts an integrated "motor-nut-bearing" design, including a motor unit, a transmission unit, a housing unit, and a sensing unit.

[0042] The motor unit is used to convert electrical energy into rotational kinetic energy of the motor rotor;

[0043] The transmission unit converts the rotational motion of the nut into the linear motion of the screw through a reverse lead screw pair, and transmits the axial load to the housing through the lead screw pair and bearing assembly.

[0044] The outer shell unit is used to bear the final load, while also protecting the internal structure, providing a seal, and providing mounting positions for the self-lubricating radial joint bearings at both ends of the linear joint.

[0045] The sensing unit is used to detect the rotational speed, displacement, and tensile and compressive forces acting on the linear joint during operation.

[0046] Furthermore, in one embodiment, the motor unit adopts an integrated design combining a reverse-type lead screw pair nut and a motor rotor, with the motor rotor bonded to the outer circle of the nut, directly driving the nut to rotate. The lead screw pair adopts a large lead design, which can appropriately reduce the motor speed and avoid excessive noise and increased friction and wear caused by excessive speed. Simultaneously, a symmetrical double-helix force-increasing structure is designed on the outer circle of the nut, with symmetrical double-helix force-increasing grooves set on the outer circle. The parametric equation of the right helix is:

[0047]

[0048] Where θ = ωt, ω is the angular velocity, b = p / 2π = acotβ, β is the helix angle, p is the pitch; x and y are the coordinates of the helix projected onto the xoy plane, a is the radius of the cylinder encircled by the helix, and z is the height of the point on the helix;

[0049] Therefore, by making their phase difference π, and starting from the symmetrical sides of the outer circle of the nut, spiraling in the same direction, with the two spiral lines symmetrical about the center of the outer circle axis of the nut, they can achieve mass complementarity. The resulting symmetrical double spiral force-increasing groove can minimize the impact on the dynamic balance of the nut. At the same time, after the adhesive bonding the rotor magnet has cured, it provides a radial anti-detachment force to the rotor magnet during rotation, preventing the rotor magnet from detaching from the outer circle of the nut during rotation and ensuring the fit of the rotor magnet.

[0050] Here, the maximum lead is greater than 2mm. Compared to the lead currently used, which is mostly less than 2mm, this invention uses a lead of 3mm. When the same linear speed is achieved, the motor speed can be appropriately reduced, effectively avoiding excessive temperature rise and noise due to excessive speed, which in turn leads to a decline in the performance of the lead screw pair.

[0051] Preferably, in some embodiments, combined with Figures 1 to 7 The motor unit includes a reverse lead screw nut 7, a motor stator 9, and a motor rotor 10. The motor stator 9 is glued to the housing 8, and the motor rotor 10 is glued to the outer circumference of the reverse lead screw nut 7. This integrated design of the motor rotor and nut significantly reduces space requirements. The outer circumference of the nut has symmetrical spiral guide grooves to generate a radial anti-disengagement force on the motor rotor 10 at high speeds, ensuring that the motor rotor 10 is firmly fixed to the reverse lead screw nut 7 and will not come loose.

[0052] Preferably, the motor wire exits through the motor outlet hole 23 on the housing 8.

[0053] Preferably, steps are provided on both the housing 8 and the reverse lead screw pair nut 7 to avoid the magnetic lines of force of the rotor magnet, thereby preventing leakage of magnetic flux from the motor rotor magnet and ensuring the normal operation of the motor.

[0054] Furthermore, in one embodiment, the transmission unit adopts an integrated design combining a reverse-type lead screw pair nut and an angular contact ball bearing inner ring. A high-power-density, high-thrust offset angular contact ball bearing is designed for the long nut structure. To improve the thrust density of the linear joint, the bearing raceway adopts a design with small adaptability, large contact angle, and large steel balls. The outer circle of the nut is directly used as the inner ring of the angular contact ball bearing, and a large contact angle bearing raceway is machined on the outer circle of the nut. This design can effectively shorten the axial space of the linear joint and ensure the axial load-bearing capacity of the entire linear joint.

[0055] Here, a large contact angle refers to a bearing contact angle of 45°, and a large steel ball refers to increasing the diameter of the steel ball to increase the contact between the steel ball and the bearing raceway during movement, thereby achieving higher load capacity.

[0056] Preferably, in the transmission unit, the reverse lead screw pair adopts a design with a high-thrust bearing fixed end and a high-strength support end. The fixed end adopts an integrated angular contact ball bearing, and the support end adopts a deep groove ball bearing.

[0057] More preferably, the deep groove ball bearing is fixed by using a step on the nut end cap and a shaft elastic retaining ring to fix the inner ring of the deep groove ball bearing while the outer ring floats, so as to adapt to the error caused by the different deformation of parts made of different materials when the temperature changes.

[0058] Preferably, the transmission unit has a limiting function at one end of the reverse lead screw pair. By radially contacting the limiting screw with the same lead spiral step, it can achieve the function of mechanical zero point. At the same time, it can avoid the extreme situation where the starting torque increases or even cannot be disengaged due to the axial surface contact between the lead screw and the end cover.

[0059] Preferably, in some embodiments, combined with Figures 1 to 7 The transmission unit includes a reverse lead screw pair 3, an angular contact ball bearing 6, a reverse lead screw pair nut 7, a nut end cap 12, a deep groove ball bearing 13, and a shaft elastic retaining ring 14. Axial movement is converted from the rotational motion of the reverse lead screw pair nut 7 to the linear motion of the reverse lead screw pair 3 via the reverse lead screw pair. Axial fixation is achieved by fixing one end to the angular contact ball bearing 6 and supporting the other end to the deep groove ball bearing 13. An integrated design of the inner ring of the angular contact ball bearing and the lead screw pair nut is adopted, directly combining the inner ring of the angular contact ball bearing 6 with the outer circle of the reverse lead screw pair nut 7, reducing the radial space of the linear joint. The left end of the outer ring of the angular contact ball bearing 6 is fixed by the front end cap 5, and the right end is fixed by the step of the housing 8. The preload of the angular contact ball bearing 6 can be adjusted by adjusting the thickness of the step surface of the front end cap 5. The angular contact ball bearing 6 is installed at the left end of the reverse lead screw pair nut 7, and the right end of the reverse lead screw pair nut 7 is connected to the nut end cap 12 by screws. The left end of the inner ring of the deep groove ball bearing 13 is fixed by a step on the nut end cover 12, and the right end of the inner ring is fixed by a shaft elastic retaining ring 14. The shaft elastic retaining ring 14 is stuck in the groove of the nut end cover 12, and the outer ring of the deep groove ball bearing 13 floats to adapt to the error caused by the different deformation of different material parts due to temperature rise during actual use, so as to achieve adaptive adjustment. Among the screws connecting the nut end cover 12 and the screw pair nut 7 of the lead screw pair, there is a long limit screw 11, which is used for mechanical limit of the lead screw pair. The limit screw 11 makes radial contact with the step on the lead screw 3 of the lead screw pair, so as to avoid the extreme situation that the starting torque will increase or even be unable to disengage due to the axial surface contact between the lead screw 3 of the lead screw pair and the nut end cover 12. At the same time, it serves as a mechanical zero point for the encoder, which facilitates the control and adjustment of the entire linear joint.

[0060] Furthermore, in one embodiment, the self-lubricating radial spherical bearings at both ends of the housing unit are fixed to the left and right bearing sleeves by a flanging and riveting process. The left bearing sleeve is threaded to the lead screw, and the right bearing sleeve is threaded to the tension and compression sensor.

[0061] Preferably, both the left and right bearing sleeves are loosened by radial threads of concave end set screws.

[0062] Preferably, in some embodiments, combined with Figures 1 to 7The outer casing unit includes a left bearing sleeve 1, a self-lubricating radial spherical bearing 2, a front cover 5, a housing 8, a rear cover 22, a right bearing sleeve 19, and a self-lubricating radial spherical bearing 20. The left end of the outer ring of the angular contact ball bearing 6 is fixed by the front cover 5, and the right end is fixed by the step of the housing 8. The preload of the angular contact ball bearing 6 can be adjusted by adjusting the thickness of the step surface of the front cover 5. The front cover 5 and the housing 8 are fixed together with screws, and the rear cover 22 and the housing 8 are fixed together with screws. The outer circle of the support guide sleeve 4 is glued to the front bearing cover 5, and the inner ring is fitted with the shaft of the reverse lead screw 3. It is made of PTFE material and has a small coefficient of friction when in contact with the reverse lead screw 3, thus providing support. The left end of the reverse lead screw 3 is threaded to the left bearing sleeve 1 and is secured with a concave end set screw to prevent loosening. The outer ring of the self-lubricating radial spherical bearing 2 is fixed to the left bearing sleeve 1 by a flanging and riveting process, and the inner ring can be flipped within a certain angle. The right end of the reverse lead screw 3 is threaded to the right bearing sleeve 19, and the thread is prevented from loosening by using a concave end set screw; the self-lubricating radial spherical bearing 20 uses a flanging and riveting process to fix the outer ring to the right bearing sleeve 19, and the inner ring can be flipped within a certain angle; the rear end cover 22 is threaded to the tension and pressure sensor 18, and the thread is loosened by using a concave end set screw; the tension and pressure sensor 18 is threaded to the right bearing sleeve 19, and the thread is loosened by using a concave end set screw.

[0063] Furthermore, in one embodiment, the sensing unit includes an encoder and a tension / compression sensor. The encoder is built into the linear joint, and one end of the tension / compression sensor is threadedly connected to the rear end cover of the housing unit, and the other end is threadedly connected to the right bearing sleeve, which enables the measurement of the tension and compression force on the linear joint during operation.

[0064] Preferably, the encoder magnetic sheet is glued to the nut end cover, and the encoder PCB board is connected and installed on the rear end cover. The encoder magnetic sheet rotates together with the nut end cover and the nut of the lead screw pair, and the rotation speed and displacement can be measured directly by the rotation of the magnetic sheet.

[0065] Preferably, in some embodiments, combined with Figures 1 to 7The sensing unit includes an encoder magnetic sheet 15, an encoder PCB board 16, and a tension / compression sensor 18. The encoder PCB board 16 is fixed to the rear end cover 22 by washers 17 and screws. The encoder magnetic sheet 15 is glued to the nut end cover 12. The distance between the encoder magnetic sheet 15 and the encoder PCB board 16 meets the encoder's reading conditions, allowing direct measurement of rotational speed via the rotation of the magnetic sheet 15. Position measurement is achieved through the mechanical zero point, rotational speed, and the lead of the inverse lead screw pair. One end of the tension / compression sensor 18 is threaded to the rear end cover 22, and the other end is threaded to the right bearing sleeve 19. Different responses are generated by a pressure strain gauge, and the output is finally transmitted through a bridge amplifier circuit, enabling real-time monitoring of tension and compression during the operation of the linear joint.

[0066] The working process of the linear joint in the integrated "motor-nut-bearing" design formed by the above embodiments is as follows:

[0067] (1) During forward transmission, a command is input to the linear joint, and the motor unit operates. The motor rotor 10 directly drives the reverse lead screw pair nut 7 to rotate. The reverse lead screw pair converts the rotational motion of the reverse lead screw pair nut 7 into the linear motion of the reverse lead screw pair screw shaft 3. The reverse lead screw pair screw 3 extends or retracts. The load is transmitted to the reverse lead screw pair nut 7 through the reverse lead screw pair screw 3. The reverse lead screw pair nut 7 is transmitted to the front end cover 5 and housing 8 of the outer casing unit through the angular contact ball bearing 6. The nut end cover 12 and the deep groove ball bearing 13 fixed by the shaft elastic retaining ring 14 mainly... Bearing radial loads and part of the axial loads, it mainly serves a supporting function. The inner rings of the self-lubricating radial joint bearings 2 and 20 are respectively sleeved on the shafts fixed to the humanoid robot's legs (or arms). The inner rings can rotate at a certain angle to meet the angle requirements of the humanoid robot under different working conditions. The self-lubricating radial joint bearing 2 is the extended end, and the self-lubricating radial joint bearing 20 is the fixed end. The self-lubricating radial joint bearing 2 and the left bearing sleeve 1 follow the reverse lead screw 3 to perform linear motion (extend or retract), realizing the movement of the humanoid robot's legs (or arms). During the movement, the tension and compression sensor 18 measures and provides feedback on the tension and compression of the linear joint in real time. The encoder magnetic sheet 15, which is bonded to the nut end cap 12, rotates together with the nut end cap 12 and the reverse lead screw nut 7. By measuring the angle, angular velocity, and angular acceleration, the lead screw pair lead is substituted into the calculation, and finally, real-time data of rotational speed and displacement can be obtained and transmitted to the controller to facilitate the speed control and adjustment of the linear joint.

[0068] (2) During reverse transmission, the humanoid robot is in a buffer state. The shaft at the joint of the humanoid robot transmits the load to the self-lubricating radial joint bearing 2. The self-lubricating radial joint bearing 2 and the left bearing sleeve 1 apply force to the reverse lead screw pair. At this time, the linear motion of the lead screw 3 of the reverse lead screw pair is converted into the rotational motion of the nut 7 of the reverse lead screw pair. The load is transmitted to the nut 7 of the reverse lead screw pair through the lead screw 3 of the reverse lead screw pair. The nut 7 of the reverse lead screw pair is transmitted to the front end cover 5 and the housing 8 of the outer shell unit through the angular contact ball bearing 6. The nut end cover 12 and the deep groove ball bearing 13 fixed by the shaft elastic retaining ring 14 mainly bear the radial load and part of the axial load, and mainly play a supporting role. The reverse transmission plays a buffer role for the linear joint and the humanoid robot, avoiding structural damage and destruction to the linear joint and the humanoid robot under some extreme working conditions.

[0069] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and extensions without departing from the actual situation and conforming to the design principles. These improvements and extensions should also be considered as references to the content of the present invention and should be considered within the scope of protection of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included in the present invention.

Claims

1. A linear joint with an integrated "motor-nut-bearing" design, characterized in that, The linear articulated joint adopts an integrated design of "motor-nut-bearing", including a motor unit, transmission unit, housing unit and sensing unit; The motor unit is used to convert electrical energy into rotational kinetic energy of the motor rotor; The transmission unit converts the rotational motion of the nut into the linear motion of the screw through a reverse lead screw pair, and transmits the axial load to the housing through the lead screw pair and bearing assembly. The outer shell unit is used to bear the final load, while also protecting the internal structure, providing a seal, and providing mounting positions for the self-lubricating radial joint bearings at both ends of the linear joint. The sensing unit is used to detect the rotational speed, displacement, and tensile and compressive forces of the linear joint during operation. The motor unit adopts an integrated design combining a reverse-type lead screw pair nut and a motor rotor, with the motor rotor bonded to the outer circle of the nut, directly driving the nut to rotate. The lead screw pair features a large lead design, and a symmetrical double-helix force-increasing structure is designed on the outer circle of the nut, with symmetrical double-helix force-increasing grooves on the outer circle. The parametric equation of the right helix is: ； in , Angular velocity, , Where p is the helix angle and p is the pitch. x , y These are the coordinates of the helix projected onto the xoy plane. a It is the radius of the cylinder encircled by the helix, and z is the height of a point on the helix; The symmetrical double-helix force-increasing groove is used to minimize the impact on the dynamic balance of the nut. At the same time, after the adhesive bonding the rotor magnet has cured, it provides a radial anti-detachment force to the rotor magnet during rotation, so as to prevent the rotor magnet from detaching from the outer circle of the nut during rotation and ensure the fit of the rotor magnet. The transmission unit adopts an integrated design combining a reverse screw pair nut and an angular contact ball bearing inner ring. It features a high-power density, high-thrust offset angular contact ball bearing designed for long nut structures, and the bearing raceway adopts a design with small adaptability, large contact angle, and large steel balls. The outer circle of the nut is directly used as the inner ring of the angular contact ball bearing, and a large contact angle bearing raceway is machined on the outer circle of the nut. In the transmission unit, the reverse lead screw pair adopts a design with a high-thrust bearing fixed end and a high-strength support end. The fixed end adopts an integrated angular contact ball bearing, and the support end adopts a deep groove ball bearing. The deep groove ball bearing is fixed by using the step of the nut end cap and the elastic retaining ring of the shaft to fix the inner ring of the deep groove ball bearing and make the outer ring float, so as to adapt to the error caused by the different deformation of parts made of different materials when the temperature changes. The transmission unit has a limiting function at one end of the reverse lead screw pair. It achieves the function of mechanical zero point by radially contacting the limit screw with the same lead spiral step. At the same time, it avoids the extreme situation where the starting torque of the motor increases or even cannot be disengaged due to the axial surface contact between the lead screw and the end cover.

2. The linear joint with integrated "motor-nut-bearing" design according to claim 1, characterized in that, The self-lubricating radial spherical bearings at both ends of the outer shell unit are fixed to the left and right bearing sleeves by a flanging and riveting process. The left bearing sleeve is threaded to the lead screw, and the right bearing sleeve is threaded to the tension and compression sensor.

3. The linear joint with integrated "motor-nut-bearing" design according to claim 2, characterized in that, Both the left and right bearing sleeves are secured with concave-end set screws with radial threads to prevent loosening.

4. The linear joint with integrated "motor-nut-bearing" design according to claim 1, characterized in that, The sensing unit includes an encoder and a tension / compression sensor. The encoder is built into the linear joint. One end of the tension / compression sensor is threaded to the rear end cover of the housing unit, and the other end is threaded to the right bearing sleeve, so as to realize the measurement of the tension and compression force on the linear joint during operation.

5. The linear joint with integrated "motor-nut-bearing" design according to claim 4, characterized in that, The encoder has its encoder magnetic sheet glued to the nut end cover, and the encoder PCB board is connected and installed on the rear end cover. The encoder magnetic sheet rotates together with the nut end cover and the nut of the lead screw pair, and the speed and displacement are measured directly through the rotation of the magnetic sheet.

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