Joint module of humanoid robot

Abstract

The application provides a joint module of a humanoid robot, which comprises a shell, a bearing and a planetary reducer arranged in the shell; an elastic coating layer with a thickness of 0.8 mm is arranged on the outside of the gear ring of the planetary reducer; the inner and outer rings of the bearing are connected with the elastic coating layer and the shell respectively; the planetary reducer comprises oppositely arranged first and second planet carriers; the first planet carrier is in a circular ring shape and comprises alternating stress zones and non-stress zones; each of the stress zones and the non-stress zones is provided with three sections; the stress zones are thickened; the non-stress zones are hollowed out; the planetary gears of the planetary reducer are arranged in the stress zones; the second planet carrier is fixed in the shell; the central hole of the first planet carrier is provided with an inner tapered surface; a wedge-shaped bushing matched with the central hole of the planet carrier is further arranged in the shell; the material of the wedge-shaped bushing is shape memory alloy; and the wedge-shaped bushing axially extends to the side where the second planet carrier is located when the temperature reaches a set value.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical hand, in particular to a joint module of a humanoid robot. BACKGROUND

[0002] The joint module of the humanoid robot is a core unit for realizing flexible movement, which is usually highly integrated by a motor, a reducer, a sensor, a driving controller, and a bearing and a shell support structure. The action flow is as follows: after the driving controller receives a movement instruction, the driving motor outputs high-speed low-torque rotation; the reducer greatly reduces the rotation speed and increases the torque output through gear meshing; the sensor feedbacks the joint angle, rotation speed and load torque in real time to form a closed-loop control; and the support structure bears the mechanical support, force transmission and heat dissipation functions.

[0003] At present, the planetary reducer is widely used in the joint module of the humanoid robot due to its high power density and strong torque transmission capacity. However, its inherent design defects are particularly prominent in high dynamic humanoid joints.

[0004] 1. Fixed backlash and meshing accuracy decay: the traditional planetary reducer needs to preset a fixed backlash to prevent jamming, but the elastic deformation of the gear under high load will aggravate the meshing misalignment, because the planetary carrier bears periodic non-uniform load during operation. That is, the three planetary gears are not simultaneously and uniformly stressed, and the maximum load appears at the position where the gear tooth meshing line is perpendicular to the planetary carrier axis. This leads to nonlinear expansion of the actual backlash, resulting in a decrease in repeated positioning accuracy.

[0005] 2. Bending moment risk caused by planetary wheel radial displacement: when the humanoid joint bears static / dynamic partial load, the planetary wheel produces radial displacement under the action of meshing force. The force applied to the planetary carrier will deviate from the bearing support center, forming an eccentric load. Under the constraint of the bearing support point, the eccentric load will induce the planetary carrier to produce out-of-plane bending moment. In the process of high-frequency start-stop, direction change or dynamic balance of the humanoid robot, the repeated alternating of the bending moment will lead to serious consequences such as abnormal wear of the bearing, deformation of the planetary carrier, increase of vibration and noise, and decrease of transmission stiffness. SUMMARY

[0006] The present application solves the above technical problems and provides a joint module of a humanoid robot.

[0007] The technical solution of the present application is a joint module of a humanoid robot, which comprises a shell and a bearing and a planetary reducer built-in the shell.

[0008] The outer side of the gear ring of the planetary reducer is provided with an elastic coating layer with a thickness of 0.8 mm, the inner and outer rings of the bearing are connected with the elastic coating layer and the shell respectively, the planetary reducer comprises oppositely arranged first and second planet carriers, the first planet carrier is in a circular ring shape and comprises alternating stress zones and non-stress zones, each of the stress zones and the non-stress zones is provided as three segments, the stress zones are thickened, the non-stress zones are hollowed out, the planet wheels of the planetary reducer are arranged in the stress zones, the second planet carrier is fixed in the shell, the central hole of the first planet carrier is provided as an inner tapered surface, the shell is further provided with a wedge-shaped bushing matched with the central hole of the planet carrier, the wedge-shaped bushing is made of shape memory alloy, and the wedge-shaped bushing axially extends to the side where the second planet carrier is located when the temperature reaches a set value.

[0009] As an implementation form, the elastic coating layer is a PEEK coating layer.

[0010] As an implementation form, the shell comprises a base shell and a cover shell which are detachably connected, the cover shell is provided with an end cover opposite to the other side of the base shell, the cover shell is provided with an output end connected with the gear ring, the bearing and the wedge-shaped bushing are fixed in the cover shell, the first planet carrier and the gear ring are located in the cover shell, and the second planet carrier is fixed in the base shell.

[0011] As an implementation form, the base shell is further provided with an axial flux motor, and an output end of the axial flux motor is connected with a central wheel of the planetary reducer.

[0012] As an implementation form, the base shell is further provided with an electromagnetic brake, and the electromagnetic brake is located at the bottom of the axial flux motor.

[0013] As an implementation form, the base shell is further provided with a support, the electromagnetic brake is arranged on the support, and an encoder and a drive controller are further arranged on the support.

[0014] As an implementation form, the three stress zones account for 60% of the circumferential arc segment, and the three non-stress zones account for 40% of the circumferential arc segment.

[0015] As an implementation form, the outer tapered surface of the wedge-shaped bushing has a taper of 1:50.

[0016] As an implementation form, the wedge-shaped bushing axially extends to the side where the second planet carrier is located when the temperature reaches 60 DEG C.

[0017] As an implementation form, the hollowed-out part of the non-stress zone is a through hole for airflow to flow along the radial direction.

[0018] The beneficial effect of the present application is that when the joint module of the humanoid robot has a tendency of meshing misalignment of the gear in a high load use scenario, the elastic PEEK cladding layer is compressed and deformed to adaptively fill the meshing gap and increase the contact area. At the same time, the stress area of the first planet carrier and the second planet carrier is extruded to the planet wheel shaft through material thermal expansion, thereby extruding the planet wheel and promoting the elimination of the meshing gap. The two form a bidirectional pre-tightening, which improves the gear meshing accuracy under high load. On this basis, the radial micro-displacement of the planet wheel caused by the compression of the PEEK cladding layer and the inclination of the first planet carrier and the second planet carrier are set as mechanical inputs, and a wedge-shaped bushing made of shape memory alloy material is set for self-pre-tightening.

[0019] Therefore, the joint module of the humanoid robot solves the problems of meshing accuracy decay and a series of technical problems caused by eccentric load in a high dynamic use scenario. BRIEF DESCRIPTION OF DRAWINGS

[0020] Fig. 1 An exploded view of the joint module of the humanoid robot is provided for the embodiments of the present application.

[0021] Fig. 2 A partial structure schematic view of the joint module of the humanoid robot is provided for the embodiments of the present application.

[0022] In the figure: 1, housing; 2, bearing; 3, planetary reducer; 4, gear ring; 5, first planet carrier; 6, second planet carrier; 7, stress area; 8, non-stress area; 9, center hole; 10, wedge-shaped bushing; 11, base shell; 12, cover shell; 13, end cover; 14, output end; 15, axial flux motor; 16, center wheel; 17, electromagnetic brake; 18, support; 19, encoder; 20, drive controller; 21, through hole; 22, planet wheel. DETAILED DESCRIPTION

[0023] The above and other embodiments and advantages of the present application are more fully described below in conjunction with the attached drawings. It is apparent that the described embodiments are only some of the embodiments of the present application, but not all of the embodiments.

[0024] In an embodiment, as shown in Figs. 1-2 .

[0025] The joint module of the humanoid robot provided by the embodiment comprises a shell 1, a bearing 2 and a planetary reducer 3 which are arranged in the shell 1. An elastic coating layer with a thickness of 0.8 mm is arranged outside a gear ring 4 of the planetary reducer 3. The inner and outer rings of the bearing 2 are connected with the elastic coating layer and the shell 1 respectively. The planetary reducer 3 comprises a first planet carrier 5 and a second planet carrier 6 which are arranged oppositely. Both the first planet carrier 5 and the second planet carrier 6 are in a circular ring shape and comprise stress areas 7 and non-stress areas 8 which are arranged alternately. Each of the stress areas 7 and the non-stress areas 8 is divided into three sections. The stress areas 7 are thickened, and the non-stress areas 8 are hollowed. The planetary gears 22 of the planetary reducer 3 are arranged in the stress areas 7. The second planet carrier 6 is fixed in the shell 1. A central hole 9 of the first planet carrier 5 is provided with an inner tapered surface. A wedge-shaped bushing 10 which is matched with the central hole 9 of the planet carrier is arranged in the shell 1. The wedge-shaped bushing 10 is made of shape memory alloy. When the temperature reaches a set value, the wedge-shaped bushing 10 extends axially to the side where the second planet carrier 6 is located.

[0026] In the embodiment, the elastic coating layer with a thickness of 0.8 mm is arranged outside the gear ring 4 of the joint module of the humanoid robot to solve the problem of the reduction of the gear meshing accuracy under high load. Specifically, the elastic PEEK coating layer is arranged outside the gear ring 4 made of hard stainless steel. The PEEK coating layer with a thickness of about 0.8 mm can be compressed and deformed to adapt to the non-uniform stress characteristics of the three planetary gears 22 under the high-torque use scenario. Meanwhile, the first planet carrier 5 and the second planet carrier 6 of the joint module of the humanoid robot are arranged asymmetrically. That is, the stress areas 7 of the first planet carrier 5 and the second planet carrier 6 are thickened, and the non-stress areas 8 are hollowed. Then, the thermal capacity of the locally thickened areas of the first planet carrier 5 and the second planet carrier 6 is larger. When the temperature rises, the internal and external temperature difference causes the material to expand, which naturally generates the extrusion trend to the wheel shaft of the planetary gear 22. Therefore, when the gears have the tendency of meshing misalignment under the high-load use scenario, the elastic PEEK coating layer is compressed and deformed to adaptively fill the meshing gap and increase the contact area. Meanwhile, the stress areas 7 of the first planet carrier 5 and the second planet carrier 6 expand and extrude the wheel shaft of the planetary gear 22, thereby extruding the planetary gear 22 and eliminating the meshing gap. The two form bidirectional pre-tightening, which improves the gear meshing accuracy under high load.

[0027] On this basis, the radial micro-displacement of the PEEK cladding layer under compression generates the planetary gear 22, and the inclination of the first planetary carrier 5 and the second planetary carrier 6 is the mechanical input, and the wedge-shaped bushing 10 made of shape memory alloy material is arranged to be self-prestressed. Because the central hole 9 of the first planetary carrier 5 is an inner tapered surface, the outer tapered surface of the wedge-shaped bushing 10 matches it, when the first planetary carrier 5 and the second planetary carrier 6 appear inclination, the tapered surface contact pressure of the wedge-shaped bushing 10 is unevenly distributed, which causes the wedge-shaped bushing 10 to change phase due to frictional heating and temperature rise, and the wedge-shaped bushing 10 expands axially to the side where the second planetary carrier 6 is located, and outputs an axial force to the first planetary carrier 5, so that the radial pre-tightening force is automatically generated.

[0028] In summary, the joint module of the humanoid robot solves the meshing precision decay in high dynamic use scenarios and a series of technical problems caused by eccentric load.

[0029] In an embodiment, as shown in Fig. 2 .

[0030] The joint module of the humanoid robot provided in the embodiment has a PEEK cladding layer.

[0031] In the embodiment, the elastic cladding layer of the gear ring 4 is made of PEEK material, and the PEEK layer is cladded on the outer side surface of the planetary gear ring 4, with a thickness of 0.8 mm. On this basis, a certain proportion of bronze powder can be mixed in the PEEK layer, and when the load torque exceeds a certain value, such as more than 50 N·m, the PEEK cladding layer is compressed and deformed to fill the tooth side gap, and at the same time, the bronze powder is precipitated to form a solid lubricating film, realizing dynamic gap adjustment and wear self-compensation.

[0032] In an embodiment, as shown in Fig. 2 .

[0033] The joint module of the humanoid robot provided in the embodiment has a PEEK cladding layer.

[0034] In the embodiment, the housing 1 is modularly designed, including a detachably connected base shell 11 and a cover shell 12, and the cover shell 12 is provided with an end cover 13 on the other side relative to the base shell 11, forming a relatively closed cavity, and the cover shell 12 is integrated with the output end 14 connected to the gear ring 4, and the bearing 2 and the wedge-shaped bushing 10 are fixed. The first planetary carrier 5 and the gear ring 4 are located in the cavity of the cover shell 12, and the second planetary carrier 6 is fixed in the base shell 11. The split structure of the housing 1 facilitates maintenance, and can effectively ensure the coaxiality of the transmission assembly.

[0035] In one embodiment, as shown in Fig. 1 .

[0036] The joint module of the humanoid robot provided in the embodiment further comprises an axial flux motor 15 arranged in the base shell 11, and an output end 14 of the axial flux motor 15 is connected to a sun gear 16 of the planetary reducer 3. The base shell 11 further comprises an electromagnetic brake 17 arranged at the bottom of the axial flux motor 15. The base shell 11 further comprises a support 18, and the electromagnetic brake 17 is arranged on the support 18. The support 18 further comprises an encoder 19 and a drive controller 20.

[0037] In the embodiment, the axial flux motor 15 and the reducer are integrated in the base shell 11, and specifically, the output end of the axial flux motor 15 is connected to the sun gear 16 of the planetary reducer 3. The working principle is that the output shaft of the axial flux motor 15 drives the sun gear 16 to rotate, the planetary gear 22 is installed on the fixed first planetary carrier 5 and the second planetary carrier 6, and is engaged with the sun gear 16, and at the same time, the planetary gear 22 is engaged with the inner ring 4, and the inner ring 4 is driven to transmit the resultant motion to the output end 14.

[0038] In the embodiment, the electromagnetic brake 17 is arranged at the bottom of the axial flux motor 15 and adopts a normally closed design. The working principle is that when normally powered, the electromagnetic brake 17 is attracted by electromagnetic force to maintain the separation of the brake pad, so that the axial flux motor 15 can rotate freely. When power is off or a fault occurs, the electromagnetic brake 17 is released by spring force, so that the brake pad is pressed tightly, thereby locking the shaft of the axial flux motor 15.

[0039] In the embodiment, the support 18 is fixed to the inner wall of the base shell 11, and the electromagnetic brake 17, the absolute value encoder 19, and the drive controller 20 are installed on the support 18 in layers. The drive controller 20 is fed back with detection signals from the encoder 19 to monitor the rotation angle of the axial flux motor 15 in real time. The drive controller 20 can send a release instruction to the electromagnetic brake 17 or output a PWM drive signal to the axial flux motor 15. The axial flux motor 15 transmits torque through the planetary reducer 3, and realizes speed reduction and torque increase through the transmission of the planetary reducer 3.

[0040] In one embodiment, as shown in Fig. 1 .

[0041] The joint module of the humanoid robot provided in the embodiment comprises three force receiving areas 7 occupying 60% of the circumferential arc segment and three non-force receiving areas 8 occupying 40% of the circumferential arc segment.

[0042] In the embodiment, the first planet carrier 5 adopts an asymmetric structure, that is, the three force receiving areas 7 account for 60% of the circumferential arc, and the thickness is increased by 20%. The three non-force receiving areas 8 account for 40% of the circumferential arc, and the radial through holes 21 are arranged. The force receiving area 7 is pre-tilted by 0.1°, and forms a 1:50 tapering fit with the wedge bushing 10. Therefore, the thermal capacity of the locally thickened area of the first planet carrier 5 and the second planet carrier 6 is larger, and the temperature difference between the inside and the outside causes the material to expand in gradient when the temperature rises, and naturally generates the extrusion trend to the wheel shaft of the planet wheel 22.

[0043] In an embodiment, as shown in Fig. 1

[0044] The joint module of the humanoid robot provided in the embodiment is that the wedge bushing 10 axially extends to the side where the second planet carrier 6 is located when the temperature reaches 60℃.

[0045] In the embodiment, the wedge bushing 10 is made of copper-nickel-tin shape memory alloy. When the planet carrier appears a tilt angle, the outer taper surface of the wedge bushing 10 bears a gradient pressure, and the local friction is warmed to 60℃ to trigger a phase change, so that the wedge bushing 10 axially extends to the direction of the second planet carrier 6. When the axial extension amount reaches 0.12mm, the radial elastic expansion of 0.05mm is generated, and a self-adjusting pre-tightening force is formed.

[0046] In an embodiment, as shown in Fig. 1

[0047] The joint module of the humanoid robot provided in the embodiment is that the hollow part of the non-force receiving area 8 is the through hole 21 for the airflow to flow along the radial direction.

[0048] In the embodiment, the through hole 21 of the non-force receiving area 8 constitutes a cooling flow channel, and the operation of the planet wheel 22 and the gear ring 4 generates airflow, which flows to the surface of the wedge bushing 10 through the through hole 21 and can carry away heat.

[0049] In an embodiment, the joint module of the humanoid robot further includes a tilt angle sensor arranged near the force receiving area 7 of the first planet carrier 5 and the second planet carrier 6, to monitor the tilt angle change of the first planet carrier 5 and the second planet carrier 6 in real time. A temperature sensor is embedded on the surface of the wedge bushing 10 to monitor the temperature change of the wedge bushing 10 in real time. A micro heating sheet is arranged around the wedge bushing 10, and a piezoelectric fan with adjustable wind speed is integrated in the through hole 21 of the non-force receiving area 8. The tilt angle sensor, the temperature sensor, the micro heating sheet and the piezoelectric fan are all connected to the driving controller 20, and through the fuzzy PID algorithm, the driving controller 20 dynamically adjusts the heating of the micro heating sheet or the cooling intensity of the piezoelectric fan.

[0050] ​​In this embodiment, when the gear meshing misalignment tendency occurs in the high load use scenario, first, the mechanical response, that is, the elastic PEEK coating layer is compressed and deformed to fill the meshing gap. The stress area 7 of the first planet carrier 5 and the second planet carrier 6 extrudes the wheel shaft of the planet wheel 22 to form a two-way pre-tightening. Then, through sensing detection, that is, the laser inclination sensor monitors the inclination angle change of the planet carrier in real time, and the infrared temperature sensor array captures the surface temperature distribution of the wedge bushing 10 in real time. Then, the micro heating sheet and the piezoelectric fan respond to the PID dynamic adjustment, introduce active predictive compensation in the adaptive system, and improve the response speed and accuracy.

[0051] The above specific embodiments further illustrate the purposes, technical solutions, and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A joint module of a humanoid robot, characterized by, The housing and the bearing built-in the housing, the planetary reducer; The elastic coating layer with a thickness of 0.8 mm is arranged outside the ring gear of the planetary reducer, the inner and outer rings of the bearing are connected with the elastic coating layer and the housing respectively, the planetary reducer comprises oppositely arranged first and second planet carriers, the first and second planet carriers are both circular rings and both comprise three alternating stress zones and non-stress zones, the stress zones are thickened, the non-stress zones are hollowed, the planet wheels of the planetary reducer are arranged in the stress zones, the second planet carrier is fixed in the housing, the central hole of the first planet carrier is provided with an inner taper surface, the housing is further provided with a wedge-shaped bushing matched with the central hole of the planet carrier, the wedge-shaped bushing is made of shape memory alloy, and the wedge-shaped bushing axially extends to the side where the second planet carrier is located when the temperature reaches a set value.

2. The joint module of the humanoid robot according to claim 1, wherein The elastic coating layer is a PEEK coating layer.

3. The joint module of the humanoid robot according to claim 1, wherein The housing comprises a base shell and a cover shell which are detachably connected, the cover shell is provided with an end cover opposite to the other side of the base shell, the cover shell is provided with an output end connected with the ring gear, the bearing and the wedge-shaped bushing are fixed in the cover shell, the first planet carrier and the ring gear are located in the cover shell, and the second planet carrier is fixed in the base shell.

4. The joint module of the humanoid robot according to claim 3, wherein The base shell is further provided with an axial flux motor, and an output end of the axial flux motor is connected with a central wheel of the planetary reducer.

5. The joint module of the humanoid robot according to claim 4, wherein The base shell is further provided with an electromagnetic brake, and the electromagnetic brake is located at the bottom of the axial flux motor.

6. The joint module of the humanoid robot according to claim 5, wherein The base shell is further provided with a support, the electromagnetic brake is arranged on the support, and the support is further provided with an encoder and a drive controller.

7. The joint module of the humanoid robot according to claim 1, wherein The three stress zones account for 60% of the circumferential arc segment, and the three non-stress zones account for 40% of the circumferential arc segment.

8. The joint module of the humanoid robot according to claim 1, wherein The taper of the outer taper surface of the wedge-shaped bushing is 1:

50.

9. The joint module of the humanoid robot according to claim 1, wherein The wedge-shaped bushing axially extends to the side where the second planet carrier is located when the temperature reaches 60℃.

10. The joint module of the humanoid robot according to claim 1, wherein The hollow part of the non-stress zone is a through hole for radial airflow.

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