Few-difference tooth speed reducer integrated at joint part of robot

Abstract

The invention discloses a few-tooth-difference speed reducer integrated on a robot joint part, and belongs to the technical field of robot joint driving. Comprising an input system, an output system and a feedback system, wherein the input system comprises a driving part and a planetary gear, and the driving part drives the planetary gear to rotate; the output system comprises a fixed gear ring box body, an output gear ring and an output flange, the fixed gear ring box body and the output gear ring are both meshed with the planetary gear, the output flange is fixedly connected with the output gear ring, and the number of teeth of the output gear ring is 1-4 smaller than that of the fixed gear ring of the fixed gear ring box body; the feedback system is connected with the output flange, detects rotating speed, torque and rotating angle data in real time and transmits the rotating speed, torque and rotating angle data to a robot main control system. The device is small in size, high in torque density and suitable for humanoid robots and auxiliary medical equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of robot joint drives, and particularly to a differential reducer with few teeth integrated in the robot joint part. Background Art

[0002] Traditional harmonic reducers or RV reducers are mostly used in the joint reducers of humanoid robots. Although they have high precision, they have problems such as limited load-bearing capacity, large volume, and high cost. Although the differential reducer with few teeth can achieve a large speed ratio, its stiffness and torque output are difficult to meet the high dynamic load requirements of humanoid robots.

[0003] In addition, there is a lack of a solution in the prior art that combines planetary reduction and differential reduction with few teeth, resulting in the need for the motor to match a low-speed and high-torque output, increasing the volume and cost of the motor. Summary of the Invention

[0004] The present invention provides a differential reducer with few teeth integrated in the robot joint part. Through a composite structure of planetary reduction and differential reduction with few teeth, high reduction ratio, large torque output and compact design are achieved, and the problems of large volume, high cost and insufficient load capacity of the reducer in the prior art are solved.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A differential reducer with few teeth integrated in the robot joint part, comprising: An input system, the input system includes a driving member and a planetary gear, and the driving member drives the planetary gear to rotate self; An output system, the output system includes a fixed ring gear box body, an output ring gear and an output flange. The fixed ring gear box body and the output ring gear are both meshed with the planetary gear, and the output flange is fixedly connected to the output ring gear. Among them, the number of teeth of the output ring gear is 1-4 teeth less than the number of teeth of the fixed ring gear of the fixed ring gear box body; A feedback system, the feedback system is connected to the output flange, and real-time detects the rotational speed, torque and angular displacement data and transmits them to the robot main control system.

[0006] As a further solution of the present invention: The planetary gear is meshed with the fixed ring gear box body and the output ring gear bidirectionally to form a differential transmission structure with few teeth.

[0007] As a further solution of the present invention: The surface of the planetary gear is nitrided, the tooth surface hardness ≥ 60HRC, and the meshing clearance between the planetary gear and the fixed ring gear box body and the output ring gear ≤ 0.02mm.

[0008] As a further solution of the present invention: The driving member includes a frameless torque motor, an input gear, and a planet carrier. The frameless torque motor is connected to the input gear located within the planet carrier through an input shaft. At least two of the planet gears are evenly rotatably embedded on the outer peripheral surface of the planet carrier, and the planet gears are all meshed with the input gear.

[0009] As a further solution of the present invention: The input gear, the planet carrier, the fixed ring gear housing, the output ring gear, and the output flange are coaxial.

[0010] As a further solution of the present invention: The feedback system includes an output shaft, a magnet assembly, and an induction integrated circuit. The output shaft is connected to the output flange through bolts. The magnet assembly is embedded at the end of the output shaft, and the induction integrated circuit is fixed within an integrated housing.

[0011] As a further solution of the present invention: The radial distance between the induction integrated circuit and the magnet assembly is 1.5 mm to ensure effective capture of magnetic field signals.

[0012] As a further solution of the present invention: The magnet assembly is a multi-pole ring magnet array, and the induction integrated circuit uses a high-resolution Hall sensor.

[0013] As a further solution of the present invention: The deceleration process of the speed reducer is divided into two stages: a planetary deceleration stage and a differential deceleration stage with a small tooth difference; Among them, the calculation formula for the planetary reduction ratio is: , In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing, is the number of teeth of the input gear; The calculation formula for the differential deceleration ratio with a small tooth difference is: , In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing, is the number of teeth of the output ring gear.

[0014] As a further solution of the present invention: The calculation formula for the total reduction ratio of the speed reducer is: , In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing, is the number of teeth of the output ring gear.

[0015] Advantages of the present invention: The deceleration process of a differential gear reducer integrated in the joint part of a robot according to the present invention is divided into two stages. First, a frameless torque motor drives the input gear to rotate, and the input gear drives the planetary gear to rotate on its own axis and drives the planet carrier to revolve along the fixed ring gear of the fixed ring gear housing, achieving planetary deceleration. Second, the planetary gear meshes with the fixed ring gear of the fixed ring gear housing and the output ring gear at the same time. The number of teeth of the output ring gear is less than that of the fixed ring gear of the fixed ring gear housing, so a speed difference occurs, achieving differential gear deceleration output. The total deceleration ratio is the product of the planetary deceleration stage and the differential gear deceleration stage, significantly improving torque output. The total deceleration ratio reaches more than 100:1, and the torque is increased by 3 - 5 times. Moreover, the input system and the reducer are integrated in layout, and the volume is reduced by 30%. It is suitable for the narrow joint space of humanoid robots and auxiliary medical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 is a schematic cross-sectional view of the structure of a differential gear reducer integrated in the joint part of a robot according to the present invention; Figure 2 is a schematic partial structure view of a differential gear reducer integrated in the joint part of a robot according to the present invention; Figure 3 is Figure 2 a schematic exploded view of the structure; Figure 4 is Figure 2 a schematic internal structure view of the middle end cover; Figure 5 is Figure 4 a schematic internal structure view of the planet carrier.

[0018] In the figures: 1. Input system; 11. Planetary gear; 12. Frameless torque motor; 13. Input gear; 14. Planet carrier; 15. Input shaft; 2. Output system; 21. Fixed ring gear housing; 22. Output ring gear; 23. Output flange; 3. Feedback system; 31. Output shaft; 32. Magnet assembly; 33. Inductive integrated circuit; 4. End cover. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0020] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, as well as a specific orientation structure and operation. Therefore, it should not be construed as a limitation to the present invention.

[0021] In addition, unless otherwise clearly specified and defined, the terms "installation", "connection", "connection", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Embodiment 1

[0023] Please refer to Figures 1-5 As shown, Embodiment 1 of the present invention provides a differential reducer with few teeth integrated in the joint part of a robot, including an input system 1, an output system 2 and a feedback system 3 arranged in an integrated box body.

[0024] Please refer to Figure 1 As shown, the input system 1 includes a driving part and a planetary gear 11, and the planetary gear 11 is driven by the driving part to rotate self. The surface of the planetary gear 11 is nitrided, the tooth surface hardness is ≥60HRC, the tooth profile is optimized to a double circular arc tooth profile to reduce the meshing impact noise, and the meshing clearance between the planetary gear 11 and the fixed tooth ring box body 21 and the output tooth ring 22 is ≤0.02mm.

[0025] Please refer to Figure 2 and Figure 5 As shown, the output system 2 includes a fixed tooth ring box body 21, an output tooth ring 22 and an output flange 23. The planetary gear 11 meshes with the fixed tooth ring of the output tooth ring 22 and the fixed tooth ring box body 21 at the same time. The planetary gear 11 meshes with the fixed tooth ring box body 21 and the output tooth ring 22 bidirectionally to form a differential transmission structure with few teeth. It should be noted that the number of teeth of the output tooth ring 22 is 1 - 4 teeth less than that of the fixed tooth ring of the fixed tooth ring box body 21 to form a differential reduction. The output flange 23 is fixedly connected to the output tooth ring 22, and the feedback system 3 is connected to the output flange 23 to detect the rotational speed, torque and angular displacement data in real time and transmit them to the main control system of the robot.

[0026] The fixed ring gear housing 21 can be made of high-strength nodular cast iron. The tooth surface is processed by gear grinding, and the accuracy grade is ISO grade 3. The material of the output ring gear 22 is nitrided steel (38CrMoAlA). Stress relief grooves are designed at the tooth roots to avoid cracks caused by stress concentration. The output flange 23 is connected to the output ring gear 22 by electron beam welding. The weld penetration depth reaches 8 mm, and a DLC (diamond-like carbon) wear-resistant coating is applied to the welding area to extend the service life.

[0027] Please refer to Figure 1 As shown, the feedback system 3 includes an output shaft 31, a magnet assembly 32, and an induction integrated circuit 33. The output shaft 31 is connected to the output flange 23 by bolts. The magnet assembly 32 is embedded at the end of the output shaft 31. The induction integrated circuit 33 is fixed in the integrated housing. The radial distance between the induction integrated circuit 33 and the magnet assembly 32 is 1.5 mm to ensure effective capture of the magnetic field signal. The magnet assembly 32 uses a multi-pole ring magnet array, such as 32 poles. The magnet material is neodymium iron boron. The pole pitch is controlled to ±0.1° by laser etching technology to ensure signal uniformity. The induction integrated circuit 33 uses a multi-channel high-resolution Hall sensor (resolution 0.1°), which is arranged on the PCB substrate, covering the full-circumference magnetic field range of the magnet assembly 32 to achieve 360° dead-angle-free signal acquisition. The sampling frequency reaches 20 kHz, and the signal is transmitted through the CAN FD bus. The bandwidth is increased to 5 Mbps, supporting real-time dynamic adjustment. The magnet assembly 32 and the Hall sensor perform non-contact signal acquisition, with strong anti-interference ability.

[0028] Signal processing flow of the feedback system 3: The magnet assembly 32 rotates with the output shaft 31, and the Hall sensor captures the magnetic field change and generates a pulse signal; after the signal is filtered and amplified, the MCU calculates the rotational speed, torque, and angular position data; the data is transmitted to the robot main control system through the CAN FD bus to form a closed-loop control, and the position accuracy reaches ±0.005°.

[0029] Working principle: The driving part of the input system 1 drives the planetary gear 11 to revolve around the fixed ring gear. Since the number of teeth Z2 of the output ring gear 22 is 1 - 4 teeth less than the number of teeth Z1 of the fixed ring gear of the fixed ring gear housing 21, the planetary gear 11 meshes with both the fixed ring gear of the fixed ring gear housing 21 and the output ring gear 22 at the same time. Due to the tooth number difference, a speed difference is generated in the output ring gear 22 to achieve speed reduction, and the output flange 23 outputs the reduced torque. At the same time, the magnet assembly 32 rotates with the output shaft 31, and the Hall sensor detects the rotational speed signal and feeds it back to the control system to achieve closed-loop speed regulation.

[0030] During the revolution of the planetary gear 11, it meshes with both the fixed ring gear of the fixed ring gear housing 21 and the output ring gear 22 at the same time. The number of teeth Z2 of the output ring gear 22 is 1 - 4 teeth less than the number of teeth Z1 of the fixed ring gear of the fixed ring gear housing 21, forming a structure with a small tooth difference. The revolution motion of the planetary gear 11 is converted into the rotation of the output ring gear 22 through the tooth difference, and the rotational speed is reduced.

[0031] The calculation formula for the reduction ratio of the small tooth difference is as follows: , In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing 21, is the number of teeth of the output ring gear 22.

[0032] Embodiment 2

[0033] Please refer to Figures 1-5 As shown, Embodiment 2 of the present invention provides a small tooth difference reducer integrated in the joint part of a robot, including an input system 1, an output system 2, and a feedback system 3 arranged in an integrated housing. The input system 1 includes a driving member and a planetary gear 11, and the planetary gear 11 is driven to rotate by itself through the driving member.

[0034] Different from Embodiment 1, the driving member of the input system 1 in this embodiment includes a frameless torque motor 12, an input gear 13, and a planet carrier 14. The frameless torque motor 12 can adopt a frameless permanent magnet synchronous motor with high torque density. The frameless torque motor 12 is connected to the input gear 13 located inside the planet carrier 14 through an input shaft 15. The frameless torque motor 12 drives the input gear 13 to rotate. The frameless torque motor 12 omits the coupling, and the axial dimension is shortened by 15%.

[0035] Please combine Figure 1 and Figure 4 As shown, a plurality of mounting grooves for mounting the planetary gear 11 are evenly formed on the outer peripheral surface of the planet carrier 14. The planet carrier 14 is integrally formed of titanium alloy (Ti - 6Al - 4V), with a lightweight design, and the surface is treated by shot peening to improve the fatigue strength. The planetary gear 11 is mounted on the pin shaft of the planet carrier 14 through a tapered roller bearing. The bearing preload is calibrated to ±0.005 mm by laser. The planetary gears 11 are all meshed with the input gear 13, and the tooth surfaces of the planetary gears 11 are in two-way meshing with the fixed ring gear housing 21 and the output ring gear 22, and the power transmission between the two is realized through the planetary gears 11. The input gear 13, the planet carrier 14, the fixed ring gear housing 21, the output ring gear 22, and the output flange 23 below the end cover 4 are coaxial.

[0036] The deceleration process of a differential gear reducer integrated in the joint part of a robot provided in the second embodiment of the present invention is divided into two stages: a planetary deceleration stage and a differential gear deceleration stage. The planetary deceleration stage is compounded on the basis of the differential gear deceleration stage in the first embodiment, significantly improving the total reduction ratio.

[0037] The specific principle is as follows: I. Planetary deceleration stage The input gear 13 is driven to rotate by the frameless torque motor 12, and the input gear 13 drives the planetary gear 11 meshed with it to rotate self. Since the fixed gear ring of the fixed gear ring housing 21 and the fixed gear ring housing 21 are integrally formed, when the planetary gear 11 rotates self, it is constrained by the meshing of the fixed gear ring of the fixed gear ring housing 21, forcing the planet carrier 14 to revolve around the central axis of the fixed gear ring of the fixed gear ring housing 21.

[0038] The calculation formula for the planetary reduction ratio is: , In the formula, is the number of teeth of the fixed gear ring of the fixed gear ring housing 21, is the number of teeth of the input gear 13.

[0039] II. Differential gear deceleration stage

[0040] During the revolution of the planetary gear 11, it meshes with the output gear ring 22 at the same time. The number of teeth of the output gear ring 22 is 1 - 4 teeth less than the number of teeth of the fixed gear ring of the fixed gear ring housing 21, forming a differential gear structure. The revolution movement of the planetary gear 11 is converted into the rotation of the output gear ring 22 through the tooth number difference, but the rotational speed is further reduced, realizing secondary deceleration.

[0041] The calculation formula for the differential gear reduction ratio is: , In the formula, is the number of teeth of the fixed gear ring of the fixed gear ring housing 21, is the number of teeth of the output gear ring 22.

[0042] III. Total reduction ratio and torque amplification

[0043] The total reduction ratio is the product of the reduction ratios of the two stages: .

[0044] In summary, the present invention realizes an ultra-high reduction ratio of more than 100:1 by connecting planetary reduction and differential reduction in series, greatly reducing the motor speed requirement, allowing the use of high-speed and small-sized motors, and reducing costs. The composite reduction mechanism of the present invention breaks through the torque density limit of traditional reducers through the synergistic effect of two stages, providing an efficient solution for high-precision and large-load scenarios such as humanoid robots and medical exoskeletons. Integrating this reducer into the knee joint drive module, the patient can adjust the gait in real time through the feedback system 3 after wearing it. Tests show that the single-joint load-bearing capacity is increased to 150 kg, and the energy consumption is reduced by 20%.

[0045] Working principle: First, the robot control system sends out a motion working signal. The frameless torque motor 12 drives the input gear 13 to rotate. The input gear 13 drives the planetary gear 11 to rotate self and drives the planet carrier 14 to revolve along the fixed gear ring of the fixed gear ring box 21, realizing planetary reduction. The planetary gear 11 meshes with the fixed gear ring of the fixed gear ring box 21 and the output gear ring 22 at the same time. The number of teeth of the output gear ring 22 is less than that of the fixed gear ring of the fixed gear ring box 21, so a speed difference appears, realizing differential reduction output. The output gear ring 22 is fixedly connected to the output flange 23 to realize torque output. At the same time, the output flange 23 is also rigidly connected to the output shaft 31 of the feedback system 3. A magnet assembly 32 is installed at the right end of the output shaft 31. There is a Hall sensor on the PCB board corresponding to the magnet assembly 32 to detect the rotation angle of the output flange 23 and feedback it to the humanoid robot control system to accurately control the rotation angle of the joint reducer. At a rated input speed of 3000 rpm, the measured output torque is 500 N·m, the efficiency is ≥92%, and there is no significant wear after continuous operation for 1000 hours, verifying the reliability and durability of the design.

[0046] The above has described the preferred embodiments of the present invention in detail and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made in accordance with the scope of the present invention application should still fall within the scope covered by the patent of the present invention.

Claims

1. A differential-less reducer integrated in the joint part of a robot, characterized in that, Comprising: An input system, the input system includes a driving member and a planetary gear, and the driving member drives the planetary gear to rotate self - rotatably; An output system, the output system includes a fixed ring gear housing, an output ring gear and an output flange, the fixed ring gear housing and the output ring gear are both meshed with the planetary gear, the output flange is fixedly connected to the output ring gear, wherein, the number of teeth of the output ring gear is 1 - 4 teeth less than the number of teeth of the fixed ring gear of the fixed ring gear housing; A feedback system, the feedback system is connected to the output flange, and real - time detects rotational speed, torque and angular displacement data and transmits them to the robot main control system.

2. The differential reducer integrated in the joint part of the robot according to claim 1, characterized in that: The planetary gear is in two - way meshing with the fixed ring gear housing and the output ring gear, forming a differential gear train with fewer teeth structure.

3. The differential reducer integrated in the joint part of the robot according to claim 2, characterized in that: The surface of the planetary gear is nitrided, the tooth surface hardness ≥ 60HRC, and the meshing clearance between the planetary gear and the fixed ring gear housing and the output ring gear ≤ 0.02mm.

4. The differential-less tooth reducer integrated in the joint part of the robot according to claim 1, characterized in that: The driving member includes a frameless torque motor, an input gear and a planetary carrier, the frameless torque motor is connected to the input gear located inside the planetary carrier through an input shaft, at least two of the planetary gears are evenly rotatably embedded on the outer peripheral surface of the planetary carrier, and the planetary gears are all meshed with the input gear.

5. The differential reducer integrated at the joint part of the robot according to claim 4, characterized in that: The input gear, the planetary carrier, the fixed ring gear housing, the output ring gear and the output flange are co - axial.

6. The differential reducer integrated in the joint part of the robot according to claim 1, characterized in that: The feedback system includes an output shaft, a magnet assembly and an induction integrated circuit, the output shaft is connected to the output flange through bolts, the magnet assembly is embedded at the end of the output shaft, and the induction integrated circuit is fixed inside an integrated box.

7. The differential reducer integrated at the joint part of the robot according to claim 6, characterized in that: The radial distance between the induction integrated circuit and the magnet assembly is 1.5mm, ensuring effective capture of magnetic field signals.

8. The differential reducer integrated in the joint part of the robot according to claim 7, characterized in that: The magnet assembly is a multi - pole annular permanent magnet array, and the induction integrated circuit uses a high - resolution Hall sensor.

9. The differential-less gear reducer integrated in the joint part of the robot according to claim 4, characterized in that: The deceleration process of the speed reducer is divided into two stages: a planetary deceleration stage and a differential gear train with fewer teeth deceleration stage; Among them, the formula for calculating the planetary reduction ratio is: ， In the formula, is the number of teeth of the fixed gear ring of the fixed gear ring housing, is the number of teeth of the input gear; The formula for calculating the differential gear train with fewer teeth reduction ratio is: ， In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing, is the number of teeth of the output ring gear.

10. The differential gear train with fewer teeth speed reducer integrated in the robot joint part according to claim 9, characterized in that: The formula for calculating the total reduction ratio of the speed reducer is: ， In the formula, is the number of teeth of the fixed ring gear of the fixed ring gear housing, is the number of teeth of the output ring gear.

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