Linear joint with motor-nut-bearing integrated design

Abstract

The invention discloses a linear joint with a motor-nut-bearing integrated design. The linear joint adapts to operation requirements and motion precision of a humanoid robot. A motor rotor-reverse lead screw nut-bearing integrated design is adopted, a motor rotor magnet is pasted on the outer circle of a nut of a reverse lead screw and fixed through a symmetrical double-spiral reinforcement structure, and the outer circle of the nut is designed to be an inner ring of an angular contact ball bearing, so that 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 rotating motion of the nut is converted into the linear motion of the lead screw through the reverse lead screw pair, meanwhile, a mechanical zero point is arranged on the encoder side, and the limiting function is achieved. An absolute value type encoder and a tension and pressure sensor are arranged in the linear joint, and the rotating speed, displacement and tension and pressure in the actual movement process can be monitored in real time.

Description

Technical Field

[0001] The present invention belongs to the fields of precision transmission technology, transmission device and humanoid robot technology, and in particular to a linear joint with an integrated "motor-nut-bearing" design. Background Art

[0002] Humanoid robots are able to adapt to the human work environment and mimic human behavior, facilitating the generation and control of multimodal interactive commands. They can adapt to the work object, work environment, and work tasks, making them more versatile and intelligent. Humanoid robots are not only a future industry but also the epitome of future industries and a focal point for major power competition. In the future, humanoid robots are expected to replace humans in tasks such as logistics, domestic services, industrial inspections, and cleaning within human work environments. They are also likely to perform tasks in specialized environments, such as dangerous outdoor environments and outer space.

[0003] Focusing on "mechanical brain, mechanical body, and mechanical limbs," and empowering humanoid robots with embodied intelligence, this research aims to develop technologies that enhance the physical fitness, skills, and intelligence of humanoid robots. The "mechanical limbs" of humanoid robots primarily include dexterous hands, rotary joints, and linear joints. Linear joints, used in the wrists, arms, and legs of humanoid robots, enable high-speed transmission and control at high speeds, requiring short-term high load capacity, high precision, and high dynamic response.

[0004] Most existing humanoid robot linear joints have short travels and long bodies, making them inadequate for the space required to fit within the joints. Furthermore, linear joints must be highly integrated, perform effectively, and offer high precision, dynamic response, and high performance. Therefore, a humanoid robot linear joint based on an inverted lead screw was needed that could meet the operational requirements and motion accuracy of humanoid robots. Summary of the Invention

[0005] The present invention aims to address the shortcomings of the prior art, such as the long axial length that prevents it from properly accommodating the space required for humanoid robot joints, and the poor temperature rise and noise levels of the lead screw assembly due to the small lead and high rotational speed. The present invention proposes a design for a linear joint for humanoid robots based on an inverted lead screw assembly that meets the operational requirements and motion accuracy of humanoid robots. The integrated "motor rotor-inverted lead screw nut-bearing" design results in a more compact structure, further enabling the linear joint to achieve high integration, high performance, high precision, high dynamic response, and high power density.

[0006] The technical solution to achieve the purpose of the present invention is: a linear joint with an integrated "motor-nut-bearing" design, wherein the linear joint adopts an integrated "motor-nut-bearing" design and includes 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 the reverse screw pair, and transmits the axial load to the housing through the screw pair and the bearing assembly;

[0009] The housing unit is used to bear the final load, protect the internal structure and seal, and provide a mounting location for the self-lubricating radial spherical bearings at both ends of the linear joint;

[0010] The sensing unit is used to detect the rotation speed, displacement and tension and pressure of the linear joint during operation.

[0011] Furthermore, the motor unit adopts an integrated design combining a reverse screw pair nut and a motor rotor, and the motor rotor is bonded to the outer circle of the nut to directly drive the nut to rotate; the screw pair adopts a large lead design, and a symmetrical double-helix force-amplifying structure is designed on the outer circle of the nut. Symmetrical double-helix force-amplifying grooves are respectively set on the outer circle. 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, and p is the pitch; x and y are the coordinates of the helix projected onto the xoy plane, a is the radius of the cylindrical surface embraced by the helix, and z is the height of the point above the helix;

[0014] The symmetrical double-helix force-enhancing groove is used to minimize the impact on the dynamic balance of the nut. At the same time, after the glue bonding the rotor magnet is cured, a radial anti-slip force is applied to the rotor magnet during rotation to prevent the rotor magnet from separating from the outer circle of the nut during rotation, thereby ensuring the fit of the rotor magnet.

[0015] Furthermore, the transmission unit adopts an integrated design combining a reverse screw pair nut and an inner ring of an angular contact ball bearing. A high-power-density, high-thrust offset angular contact ball bearing is designed for a long nut structure, and the bearing raceway adopts a design of a large steel ball with small adaptability, large contact angle, and a large contact angle. 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 screw pair adopts a design of a large thrust bearing fixed end and a high-strength supporting end, the fixed end adopts an integrated angular contact ball bearing, and the supporting end adopts a deep groove ball bearing.

[0017] Furthermore, the deep groove ball bearing is fixed by using a step of the nut end cover and an elastic retaining ring for the shaft to fix the inner ring of the deep groove ball bearing and float the outer ring, so as to adapt to the errors caused by different deformation amounts 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 screw pair, which realizes the role of mechanical zero point through radial contact between the same-lead spiral step and the limit screw, while avoiding the extreme situation where the starting torque increases or even cannot be disengaged due to axial surface contact between the screw and the end cover.

[0019] Furthermore, the self-lubricating radial spherical bearings at both ends of the housing unit use a flanging and riveting process to fix the outer rings on the left and right bearing sleeves, the left bearing sleeve is threadedly connected to the screw, and the right bearing sleeve is threadedly connected to the tension and pressure sensor.

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

[0021] Furthermore, the sensing unit includes an encoder and a tension and pressure sensor. The encoder is built into the linear joint. One end of the tension and pressure sensor is threadedly connected to the rear end cover of the shell unit, and the other end is threadedly connected to the right bearing sleeve, thereby realizing the measurement of the tension and pressure exerted on the linear joint during operation.

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

[0023] Compared with the prior art, the present invention has the following significant advantages:

[0024] (1) The present invention integrates the motor rotor and the nut of the reverse screw into an integrated design, which greatly shortens the axial size of the entire linear joint and effectively utilizes the long nut structure of the reverse screw. In response to the existing integrated design scheme, the present invention specifically designs a special symmetrical double-helix glue guide groove structure on the outer cylindrical surface of the nut of the reverse screw, and machines two sections of thread grooves on the outer cylindrical surface of the nut that are symmetrical with the center axis of the outer cylindrical axis of the nut, so that when the motor rotor drives the outer cylindrical surface of the reverse screw nut to rotate, an axial anti-slip force is applied to the rotor magnet, thereby achieving a smoother movement. At the same time, the centrally symmetrical structure will not destroy the dynamic balance of the "nut-motor", will not affect the high-speed rotation of the motor, and will help to achieve high-speed transmission of 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 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, the axial dimension of the linear joint is effectively shortened, the number of parts of the linear joint is reduced, and the error coupling caused by installation and assembly is effectively reduced, thereby ensuring the overall installation accuracy and dynamic balance of the linear joint.

[0026] (3) The present invention has a mechanical limit function at the end of the screw pair near the encoder, which also serves as a mechanical zero point for the incremental encoder, facilitating the recording and control of the rotational speed. Furthermore, the limit function is achieved by using a long screw on the end cap and the step surface of the screw pair. The limit screw is in radial contact with the step of the screw, avoiding the extreme situation where the starting torque increases or even cannot be disengaged due to axial surface contact between the screw and the end cap, thereby achieving an effective mechanical limit function.

[0027] (4) The present invention adopts a non-magnetic aluminum nut end cover at the encoder end to cooperate with the installation of the encoder magnetic plate, which ensures the integrity of the magnetic lines of force of the encoder magnetic plate and is conducive to the encoder to achieve accurate measurement; at the same time, the nut end cover 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, and the rotating body structure of the nut end cover will not affect the dynamic balance of the rotor and the nut as a whole.

[0028] The present invention is further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0033] Figure 5 The figure is a schematic diagram of the symmetrical double-helix force-amplifying structure of a nut in one embodiment.

[0034] Figure 6 FIG. 1 is a schematic diagram of the helical lines of a symmetrical double-helix force-amplifying structure in one embodiment.

[0035] Figure 7 It is a schematic diagram of the screw pair limiting mechanism in an embodiment.

[0036] Among them, the markings in the accompanying drawings are: 1-left bearing sleeve; 2-self-lubricating radial spherical bearing 1; 3-reverse screw pair screw; 4-support guide sleeve; 5-front end cover; 6-bearing; 7-reverse 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 disc; 16-encoder PCB board; 17-gasket; 18-tension and pressure sensor; 19-right bearing sleeve; 20-self-lubricating radial spherical bearing 2; 21-encoder wire outlet hole; 22-rear end cover; 23-motor wire outlet hole. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

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

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0040] In addition, if there are descriptions involving "springs", "screws", etc. in the embodiments of the present invention, the descriptions of "springs", "screws", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "springs" and "screws" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] In one embodiment, the present invention provides a linear joint with an integrated “motor-nut-bearing” design. The linear joint adopts an integrated “motor-nut-bearing” design and includes 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 the reverse screw pair, and transmits the axial load to the housing through the screw pair and the bearing assembly;

[0044] The housing unit is used to bear the final load, protect the internal structure and seal, and provide a mounting location for the self-lubricating radial spherical bearings at both ends of the linear joint;

[0045] The sensing unit is used to detect the rotation speed, displacement and tension and pressure of the linear joint during operation.

[0046] Furthermore, in one embodiment, the motor unit adopts an integrated design combining a reverse screw pair nut and a motor rotor. The motor rotor is bonded to the outer circle of the nut to directly drive the nut to rotate. The 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. At the same time, a symmetrical double-helix force-enhancing structure is designed on the outer circle of the nut, and symmetrical double-helix force-enhancing grooves are set on the outer circle. The parameter 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, and p is the pitch; x and y are the coordinates of the helix projected onto the xoy plane, a is the radius of the cylindrical surface embraced by the helix, and z is the height of the point above the helix;

[0049] It can be seen that the phase difference is π, and the two spiral lines start from the symmetrical sides of the outer circle of the nut and spiral in the same direction. The two spiral lines are symmetrical about the center axis of the outer circle of the nut, which can achieve mass complementarity. The symmetrical double-helix force-enhancing groove formed thereby can minimize the impact on the dynamic balance of the nut. At the same time, after the glue bonding the rotor magnet is cured, a radial anti-slip force is applied to the rotor magnet during the rotational motion to prevent the rotor magnet from detaching from the outer circle of the nut during rotation, thereby ensuring the fit of the rotor magnet.

[0050] Here, the large lead is greater than 2 mm. Compared to the currently used leads which are mostly less than 2 mm, the present invention adopts a lead of 3 mm. When achieving the same linear speed, the motor speed can be appropriately reduced, effectively avoiding the temperature rise and excessive noise caused by excessive speed, which in turn leads to a decrease in the service performance of the screw pair.

[0051] Preferably, in some embodiments, Figures 1 to 7 The motor unit comprises a counterscrew nut 7, a motor stator 9, and a motor rotor 10. The stator 9 is glued to the housing 8, while the rotor 10 is glued to the outer circumference of the counterscrew nut 7. The integrated design of the motor rotor and nut significantly reduces space. Symmetrical spiral glue guide grooves are provided on the outer circumference of the nut to generate a radial anti-slip force for the motor rotor 10 at high speeds, ensuring that the motor rotor 10 is firmly fixed to the counterscrew nut 7 and prevents it from dislodging.

[0052] Here, preferably, the motor wires are led out through the motor wire outlet hole 23 on the housing 8 .

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

[0054] Furthermore, in one embodiment, the transmission unit utilizes an integrated design combining a reversed screw nut and the inner race of an angular contact ball bearing. 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 utilizes large steel balls with low adaptability, high contact angle, and low friction. The outer diameter of the nut directly serves as the inner race of the angular contact ball bearing, and a high-contact-angle bearing raceway is machined onto the outer diameter of the nut. This design effectively reduces the axial space of the linear joint and ensures the axial load-bearing capacity of the entire linear joint.

[0055] Here, large contact angle means that the bearing contact angle is 45°, and large steel ball means increasing the diameter of the steel ball to increase the contact between the steel ball and the bearing raceway during movement to achieve higher load-bearing capacity.

[0056] Here preferably, in the transmission unit, the reverse screw pair adopts a design of a large thrust bearing fixed end and a high-strength supporting end, the fixed end adopts an integrated angular contact ball bearing, and the supporting end adopts a deep groove ball bearing.

[0057] Further preferably, the deep groove ball bearing is fixed by using a step of the nut end cover and an elastic retaining ring for the shaft to fix the inner ring of the deep groove ball bearing and float the outer ring, so as to adapt to the errors caused by different deformation amounts of parts made of different materials when the temperature changes.

[0058] Here, preferably, the transmission unit has a limiting function at one end of the reverse screw pair, which can realize the effect of mechanical zero point through radial contact between the spiral step with the same lead and the limiting screw, and at the same time avoid the extreme situation that the starting torque increases or even cannot be disengaged due to axial surface contact between the screw and the end cover.

[0059] Preferably, in some embodiments, Figures 1 to 7 The transmission unit includes a counterscrew pair screw 3, an angular contact ball bearing 6, the counterscrew pair nut 7, a nut end cap 12, a deep groove ball bearing 13, and a shaft circlip 14. Axial motion is converted from the rotational motion of the counterscrew pair nut 7 into linear motion of the counterscrew pair screw 3 via the counterscrew pair. Axial fixation employs an angular contact ball bearing 6 at one end and a deep groove ball bearing 13 at the other end. The inner ring of the angular contact ball bearing and the counterscrew pair nut are integrated into a design that directly couples the inner ring of the angular contact ball bearing 6 to the outer diameter of the counterscrew 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 secured by the front end cap 5, and the right end is secured by a step on 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 mounted on the left end of the counterscrew pair nut 7, and the right end of the counterscrew pair nut 7 is connected to the nut end cap 12 via screws. The left end of the inner ring of the deep groove ball bearing 13 is fixed by a step on the nut end cap 12, and the right end of the inner ring is fixed by a shaft elastic circlip 14. The shaft elastic circlip 14 is stuck in the groove of the nut end cap 12. The outer ring of the deep groove ball bearing 13 floats to adapt to the errors caused by the different deformation amounts of parts made of different materials due to temperature rise during actual use, thereby achieving adaptive adjustment. There is a longer limit screw 11 in the screw connecting the nut end cap 12 and the screw pair trans-screw nut 7, which is used for mechanical limitation of the trans-screw pair. The limit screw 11 is in radial contact with the step on the trans-screw pair screw 3 to avoid the extreme situation where the starting torque increases or even cannot be disengaged due to the axial surface contact between the trans-screw pair screw 3 and the nut end cap 12. At the same time, it acts as a mechanical zero point for the encoder, facilitating the control and adjustment of the linear joint machine.

[0060] Furthermore, in one embodiment, the self-lubricating radial spherical bearings at both ends of the housing unit use a flanging and riveting process to fix the outer rings on the left and right bearing sleeves, the left bearing sleeve is threadedly connected to the screw, and the right bearing sleeve is threadedly connected to the tension and pressure sensor.

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

[0062] Preferably, in some embodiments, Figures 1 to 7The housing unit comprises a left bearing sleeve 1, a self-lubricating radial spherical plain bearing 2, a front cover 5, a housing 8, a rear cover 22, a right bearing sleeve 19, and a self-lubricating radial spherical plain bearing 20. The left end of the outer ring of the angular contact ball bearing 6 is secured by the front cover 5, and the right end is secured by a step on the housing 8. The preload of the angular contact ball bearing 6 can be adjusted by adjusting the thickness of the step on the front cover 5. The front cover 5 and the housing 8 are fixed together by screws, while the rear cover 22 and the housing 8 are also fixed together by screws. The outer diameter of the support guide sleeve 4 is adhesively bonded to the front bearing sleeve 5. The inner ring is axially aligned with the counterscrew auxiliary screw 3 and is made of PTFE, which has a low friction coefficient when in contact with the counterscrew auxiliary screw 3, providing support. The left end of the counterscrew auxiliary screw 3 is threadedly connected to the left bearing sleeve 1, secured with a concave set screw. The outer ring of the self-lubricating radial spherical plain bearing 2 is secured to the left bearing sleeve 1 by a flanging and riveting process, and the inner ring can be tilted within a certain angle. The right end of the reverse screw auxiliary screw 3 is threadedly connected to the right bearing sleeve 19, and a concave end set screw is used to prevent the thread from loosening; the self-lubricating centripetal spherical bearing 20 uses a flanging riveting process to fix the outer ring on the right bearing sleeve 19, and the inner ring can be flipped within a certain angle; the rear end cover 22 is threadedly connected to the tension and pressure sensor 18, and a concave end set screw is used to loosen the thread; the tension and pressure sensor 18 is threadedly connected to the right bearing sleeve 19, and a concave end set screw is used to loosen the thread.

[0063] Furthermore, in one embodiment, the sensing unit includes an encoder and a tension and pressure sensor. The encoder is built into the linear joint. One end of the tension and pressure 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 can realize the measurement of the tension and pressure exerted on the linear joint during operation.

[0064] Here preferably, the encoder glues the encoder magnetic disc to the nut end cover, and the encoder PCB board is connected and installed on the rear end cover. The encoder magnetic disc rotates with the nut end cover and the nut of the screw pair, and the speed and displacement can be measured directly through the rotation of the magnetic disc.

[0065] Preferably, in some embodiments, Figures 1 to 7The sensing unit includes an encoder magnetic disc 15, an encoder PCB board 16 and a tension and pressure sensor 18. The encoder PCB board 16 is fixed to the rear end cover 22 by a gasket 17 and a screw. The encoder magnetic disc 15 is glued to the nut end cover 12. The distance between the encoder magnetic disc 15 and the encoder PCB board 16 meets the encoder reading condition. The rotation speed can be directly measured by rotating the magnetic disc 15, and the position can be measured by the mechanical zero point, rotation speed and lead of the reverse screw pair. One end of the tension and pressure sensor 18 is threadedly connected to the rear end cover 22, and the other end is threadedly connected to the right bearing sleeve 19. Different responses are generated through the pressure strain gauge, and finally output through the bridge amplifier circuit, which can monitor the tension and pressure of the linear joint in real time during operation.

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

[0067] (1) During forward transmission, a command is input to the linear joint, the motor unit operates, and the motor rotor 10 directly drives the anti-screw nut 7 of the anti-screw pair to rotate. The anti-screw pair converts the rotational motion of the anti-screw nut 7 into the linear motion of the anti-screw shaft 3, and the anti-screw 3 extends or retracts; the load is transmitted to the anti-screw nut 7 through the anti-screw screw 3, and the anti-screw nut 7 is transmitted to the front end cover 5 and the shell 8 of the housing unit through the angular contact ball bearing 6; the deep groove ball bearing 13 fixed to the nut end cover 12 and the shaft with an elastic retaining ring 14 is mainly The self-lubricating radial spherical bearing 2 and the self-lubricating radial spherical bearing 20 are respectively mounted on shafts fixed to the legs (or arms) of the humanoid robot. The inner rings can achieve a certain degree of rotation to meet the angular requirements of the humanoid robot under different working conditions. The self-lubricating radial spherical bearing 2 is the extending end, and the self-lubricating radial spherical bearing 20 is the fixed end. The self-lubricating radial spherical bearing 2 and the left bearing sleeve 1 follow the reverse screw auxiliary 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 pressure sensor 18 measures and provides real-time feedback on the tension and pressure applied to the linear joint. The encoder magnetic disc 15 bonded to the nut end cap 12 rotates with the nut end cap 12 and the reverse screw auxiliary nut 7. By measuring the angle, angular velocity, and angular acceleration, the lead of the screw auxiliary is substituted into the calculation, and finally the real-time data of the rotation 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 transfers the load to the self-lubricating radial spherical bearing 2. The self-lubricating radial spherical bearing 2 and the left bearing sleeve 1 apply force to the reverse screw pair. At this time, the linear motion of the reverse screw pair screw 3 is converted into the rotational motion of the reverse screw pair nut 7. The load is transferred to the reverse screw pair nut 7 through the reverse screw pair screw 3. The reverse screw pair nut 7 is transferred to the front end cover 5 and the shell 8 of the shell unit through the angular contact ball bearing 6. The deep groove ball bearing 13 fixed by the nut end cover 12 and the shaft with an elastic retaining ring 14 mainly bears radial loads and part of the axial load, and mainly plays a supporting role. Reverse transmission plays a buffering role on 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 is a preferred embodiment of the present invention. It should be noted that for those skilled in the art, various improvements and extensions may be made without departing from the actual situation and in accordance with the design principles. These should also be regarded as citing the contents of the present invention and should also be regarded as the scope of protection of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes that come within the meaning and range of equivalents of the claims are intended to be included in the present invention.

Claims

1. A linear joint with an integrated design of "motor-nut-bearing", characterized in that: The linear joint machine adopts an integrated design of "motor-nut-bearing", including a motor unit, a transmission unit, a housing unit and a 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 the reverse screw pair, and transmits the axial load to the housing through the screw pair and the bearing group; The housing unit is used to bear the final load, protect the internal structure and seal, and provide the installation position of the self-lubricating radial spherical bearings at both ends of the linear joint; The sensing unit is used to detect the rotation speed, displacement and tensile pressure of the linear joint during operation.

2. The linear joint with integrated design of "motor-nut-bearing" according to claim 1 is characterized in that: The motor unit adopts an integrated design combining a reverse screw pair nut and a motor rotor, and the motor rotor is bonded to the outer circle of the nut to directly drive the nut to rotate; the screw pair adopts a large lead design, and a symmetrical double-helix force-enhancing structure is designed on the outer circle of the nut, and symmetrical double-helix force-enhancing grooves are respectively set on the outer circle. The parameter equation of the right helix line is: 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 cylindrical surface embraced by the helix, and z refers to the height of the point on the helix; The symmetrical double helical force-enhancing grooves are used to minimize the influence on the dynamic balance of the nut. At the same time, after the glue bonding the rotor magnet is cured, a radial anti-slip force is given to the rotor magnet during the rotational motion to prevent the rotor magnet from detaching from the outer circle of the nut during the rotation process, thereby ensuring the fit of the rotor magnet.

3. The linear joint with integrated design of "motor-nut-bearing" according to claim 1 is characterized in that: The transmission unit adopts an integrated design combining a reverse screw pair nut and an angular contact ball bearing inner ring. An offset angular contact ball bearing with high power density and high thrust is designed for a long nut structure, and the bearing raceway adopts a design of a large steel ball with small adaptability, large contact angle, and 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.

4. The linear joint with integrated design of "motor-nut-bearing" according to claim 1 is characterized in that: In the transmission unit, the reverse screw pair adopts a design of a large thrust bearing fixed end and a high-strength supporting end, the fixed end adopts an integrated angular contact ball bearing, and the supporting end adopts a deep groove ball bearing.

5. The linear joint with integrated design of "motor-nut-bearing" according to claim 4 is characterized in that: The fixing method of the deep groove ball bearing adopts the step of the nut end cover and the shaft elastic retaining ring to fix the inner ring of the deep groove ball bearing and float the outer ring, so as to realize the error caused by the different deformation amounts of parts made of different materials when the temperature changes.

6. The linear joint with integrated design of "motor-nut-bearing" according to claim 1, characterized in that: The transmission unit has a limiting function at one end of the reverse screw pair, and realizes the effect of mechanical zero point through radial contact between the spiral step with the same lead and the limiting screw, while avoiding the extreme situation that the starting torque of the motor increases or even cannot be disengaged due to axial surface contact between the screw and the end cover.

7. The linear joint with integrated design of "motor-nut-bearing" according to claim 1, characterized in that: The self-lubricating radial spherical bearings at both ends of the housing unit are fixed to the left and right bearing sleeves by flanging and riveting. The left bearing sleeve is threadedly connected to the lead screw, and the right bearing sleeve is threadedly connected to the tension and pressure sensor.

8. The linear joint with integrated design of "motor-nut-bearing" according to claim 7 is characterized in that: The left and right bearing sleeves are both loosened by radial threads of concave-end set screws.

9. The linear joint with integrated design of "motor-nut-bearing" according to claim 1, characterized in that: The sensing unit includes an encoder and a tension and pressure sensor. The encoder is built into the linear joint. One end of the tension and pressure 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 measure the tension and pressure exerted on the linear joint during operation.

10. The linear joint with integrated design of "motor-nut-bearing" according to claim 9, characterized in that: The encoder glues the encoder magnetic sheet to the nut end cover, and the encoder PCB board is connected and installed on the rear end cover. The encoder magnetic sheet rotates with the nut end cover and the nut of the screw pair, and the rotation speed and displacement are measured directly through the rotation of the magnetic sheet.

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