High-density force-controlled joint module

Abstract

This invention relates to a high-density force-controlled joint module, comprising a housing, a PCB motor assembly, and a harmonic reducer. The PCB motor stator is fixed to one end face of the housing. The PCB motor rotor includes a shaft, a rotor hub, and a magnetic ring. The rotor hub is located at one end of the shaft, and the magnetic ring is fixed to the end face of the rotor hub. The harmonic reducer includes a wave generator, a flexure, and an output bearing. The wave generator is fixed to the other end of the shaft. One end of the flexure is fixed to the housing, and the other end is sleeved on the outside of the wave generator. The outer ring of the bearing is fixed to the housing, and a steel wheel is integrated on the inner ring of the bearing, with the steel wheel sleeved on the outside of the flexure. A strain elastomer is also provided on the connecting beam surface of the inner and outer rings of the flexure, and multiple strain elastomers form a Wheatstone full-bridge circuit. This invention achieves a volume reduction of over 40% and a force control response delay reduced to milliseconds under the same output torque through structural function reuse and deep integration of heterogeneous sensing, providing a revolutionary integrated solution for high-precision robot joints.

Description

Technical Field

[0001] This invention belongs to the field of robotics technology, and in particular relates to a high-density force-controlled joint module. Background Technology

[0002] In the field of robot joint modules, especially in applications requiring high-precision force control (such as collaborative robots and precision surgical instruments), traditional joint modules generally suffer from three major pain points: complex structure, low space utilization, and large force sensing lag. Existing technologies typically employ a series design of "motor + harmonic reducer + external force sensor," leading to the following inherent defects:

[0003] 1. Space redundancy and low density issues: Traditional motors (such as frameless torque motors) and harmonic reducers are axially stacked, requiring space for sensor installation, resulting in excessively large axial dimensions of the joint. External force sensors (such as strain gauges or six-dimensional force sensors) not only increase the module length but also introduce interference due to the long signal transmission path.

[0004] 2. Limited force control accuracy and response speed: External force sensors are usually installed at the output end, requiring indirect detection of flexspline deformation through mechanical structures, resulting in signal transmission lag. The actual stress changes of the flexspline cannot be directly captured, affecting the real-time performance of the force control closed loop.

[0005] 3. Insufficient integration of the sensing system: Position detection relies on independent photoelectric / magnetic encoders, which require additional space and increase wiring complexity; while force sensing and motion control circuits are separated, resulting in high system redundancy and decreased reliability. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a high-density force-controlled joint module with higher integration and higher torque detection response.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A high-density force-controlled joint module includes a housing, a PCB motor assembly, and a harmonic reducer. The PCB motor assembly includes a PCB motor stator and a PCB motor rotor. The PCB motor stator is fixed to one end face of the housing. The PCB motor rotor includes a shaft, a rotor hub, and a magnetic ring. The rotor hub is located at one end of the shaft, and the magnetic ring is fixed to the end face of the rotor hub, facing the PCB motor stator. The shaft is rotatably connected to the main housing via a bearing. The harmonic reducer includes a wave generator, a flexible wheel, and an output bearing. The wave generator is fixed to the other end of the shaft. One end of the flexible wheel is fixed to the housing, and the other end is sleeved on the outside of the wave generator. The output bearing includes an inner bearing ring and an outer bearing ring. The outer bearing ring is fixed to the housing. A steel wheel is integrated on the inner bearing ring and is sleeved on the flexible wheel, engaging in staggered gear transmission with the flexible wheel. A strain elastic body is also provided on the connecting beam surface of the inner and outer rings of the flexible wheel. Multiple strain elastic bodies form a Wheatstone full-bridge circuit that converts minute deformations into weak voltage signals and is connected to a control circuit board via a signal processing circuit board.

[0009] As a preferred embodiment, the housing includes a main housing with a convex cross-section and a cover plate fixed to one end of the main housing, and the control circuit board is fixed in the receiving cavity formed by the main housing and the cover plate.

[0010] As a preferred embodiment, one end of the main housing is a connecting part, the rotating shaft passes through the connecting part and is rotatably connected to the connecting part through a bearing, and the flexible wheel is sleeved outside the connecting part with a gap between it and the connecting part.

[0011] As a preferred embodiment, the outer end face of the inner ring of the output bearing is also fixed with an output disk. The output disk has a through hole in the middle, and an output hollow tube is connected to the through hole. The output hollow tube passes through the harmonic reducer and the PCB motor assembly and extends to the control circuit board.

[0012] As a preferred embodiment, the cover plate has a through hole in the middle and a convex ring A on the inner side of the cover plate. The end of the output hollow tube has a convex ring B. The cross sections of the convex ring A and the convex ring B are respectively concave and convex, and they are fitted together with a gap after being inserted.

[0013] As a preferred embodiment, the end of the output hollow tube is further provided with a metal code disk A, and the control circuit board is provided with a transmitting coil A, a receiving coil array A and a signal processing circuit A that cooperate with the metal code disk A. The metal code disk A, the transmitting coil A, the receiving coil array A and the signal processing circuit A constitute an eddy current encoder A.

[0014] As a preferred embodiment, the rotor hub is further provided with a plurality of fan-shaped recesses at equal intervals along the circumference, so that the rotor hub forms a metal code disk B. The control circuit board is provided with a transmitting coil B, a receiving coil array B and a signal processing circuit B that cooperate with the metal code disk B. The metal code disk B, the transmitting coil B, the receiving coil array B and the signal processing circuit B constitute an eddy current encoder B.

[0015] As a preferred embodiment, the system also includes a brake assembly, which is an electromagnetic adsorption brake, comprising a brake stator fixed to the end face of the housing and a brake rotor fixed to the rotor hub.

[0016] As a preferred embodiment, the wave generator includes an elliptical hub and a flexible bearing, wherein the elliptical hub is fixed to the rotating shaft, and the flexible bearing is disposed between the flexible wheel and the elliptical hub.

[0017] As a preferred embodiment, the bearing is a double-row angular contact bearing.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] This invention's joint module features a groundbreaking three-in-one architecture: a PCB motor, a harmonic reducer, and an in-situ strain sensor. The ultra-thin PCB motor stator is directly integrated onto the housing end face, with the rotor hub and magnetic ring forming a compact power unit, significantly reducing axial space. A revolutionary feature is the embedding of a strain elastomer into the flexible wheel connecting beam of the harmonic reducer, forming a Wheatstone full-bridge circuit that directly converts minute deformations of the flexible wheel into voltage signals, achieving zero-delay force-to-electricity conversion. The flexible wheel simultaneously performs both force transmission and force sensing functions, eliminating the structural redundancy of traditional external sensors. Through structural function reuse and deep integration of heterogeneous sensing, this invention achieves a volume reduction of over 40% under the same output torque, reducing force control response delay to the millisecond level, providing a revolutionary integrated solution for high-precision robot joints. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute a limitation thereof.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0022] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0023] Figure 3 and Figure 4 These are schematic diagrams of the exploded structure from two different angles of the present invention.

[0024] The attached figures are labeled as follows: 11. Main housing; 12. Cover plate; 13. Control circuit board; 21. PCB motor stator; 221. Shaft; 222. Rotor hub; 2221. Fan-shaped recess; 23. Magnetic ring; 24. Brake stator; 25. Brake rotor; 31. Elliptical hub; 32. Flexible bearing; 33. Flexible wheel; 331. Strain gauge; 34. Bearing outer ring; 35. Bearing inner ring; 41. Output disc; 42. Output hollow tube; 43. Metal code disc; 5. Bearing. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Furthermore, in the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, unless explicitly defined otherwise.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0032] like Figures 1 to 4 As shown, a high-density force-controlled joint module includes a housing, a PCB motor assembly, and a harmonic reducer. The PCB motor assembly includes a PCB motor stator 21 and a PCB motor rotor. The PCB motor stator 21 is fixed to one end face of the housing. The PCB motor rotor includes a shaft 221, a rotor hub 222, and a magnetic ring 23. The rotor hub 222 is located at one end of the shaft 221, and the magnetic ring 23 is fixed to the end face of the rotor hub 222, facing the PCB motor stator 21. The shaft 221 is rotatably connected to the main housing 11 via a bearing 5. The bearing 5 is a double-row angular contact bearing. This type of bearing has high load-bearing capacity and can withstand axial and radial composite loads simultaneously, adapting to multi-dimensional force scenarios of the joint. Simultaneously, the double-row structure enhances rigidity and reduces vibration transmission from the motor and harmonic reducer.

[0033] The harmonic reducer includes a wave generator, a flexible wheel 33, and an output bearing. The wave generator is fixed to the other end of the rotating shaft 221. One end of the flexible wheel 33 is fixed to the housing, and the other end is sleeved on the outside of the wave generator. The output bearing includes an inner bearing ring 35 and an outer bearing ring 34. The outer bearing ring 34 is fixed to the housing. A steel wheel is integrated on the inner bearing ring 35 and is sleeved on the outside of the flexible wheel 33, and the steel wheel is driven by the flexible wheel 33 through a toothed transmission. A strain elastic body 331 is also provided on the connecting beam surface of the inner and outer rings of the flexible wheel 33. Multiple strain elastic bodies 331 form a Wheatstone full-bridge circuit that converts small deformations into weak voltage signals and is connected to the control circuit board through a signal processing circuit board.

[0034] The above structure integrates the PCB motor, harmonic reducer, and strain sensor into a single design, significantly reducing the size; and the strain elastomer on the flexible wheel forms a Wheatstone full-bridge circuit, which converts deformation into electrical signals in real time, enabling direct measurement of joint torque without the need for an additional torque sensor.

[0035] The housing includes a main housing 11 with a convex cross-section and a cover plate 12 fixed to one end of the main housing 11. The control circuit board is fixed within the cavity formed by the main housing 11 and the cover plate 12. The above structure adopts modular packaging: the convex main housing and the cover plate form a sealed cavity to protect the internal circuit board and improve anti-interference capability; the control circuit board is built-in, reducing external wiring and improving electromagnetic compatibility (EMC).

[0036] One end of the main housing 11 is a connecting part. The rotating shaft 221 extends through the connecting part and is rotatably connected to the connecting part via a bearing 5. The flexible wheel 33 is sleeved outside the connecting part, with a gap between it and the connecting part. The gap between the flexible wheel and the housing connecting part prevents friction between the flexible wheel and the housing when the flexible wheel deforms, thus ensuring transmission accuracy.

[0037] An output disk 41 is fixed to the outer end face of the inner ring 35 of the output bearing. The output disk 41 has a through hole in the middle, and an output hollow tube 42 is connected to the through hole. The output hollow tube 42 passes through the harmonic reducer and the PCB motor assembly and extends to the control circuit board. The output hollow tube runs through the entire module, providing a centralized wiring path for external devices (such as sensors and cables) and avoiding cable tangling. At the same time, the through hole design facilitates the integration of rotary power supply / communication modules (such as slip rings).

[0038] The cover plate 12 has a through hole in the middle, and a raised ring A is provided on the inner side of the cover plate 12. The end of the output hollow tube 42 has a raised ring B. The cross-sections of the raised ring A and the raised ring B are respectively concave and convex, and they are fitted together with a clearance fit. The concave and convex fitting structure restricts the axial displacement of the output hollow tube 42 and prevents it from becoming loose. At the same time, the cover plate and the output hollow tube also form a labyrinth-like sealing structure, which can protect the internal circuit board. In addition, the clearance fit allows for slight radial displacement, adapts to the deformation of the flexible wheel, and avoids stress caused by rigid connection.

[0039] The end of the output hollow tube 42 is also provided with a metal code disk A43, and the control circuit board is provided with a transmitting coil A, a receiving coil array A and a signal processing circuit A that cooperate with the metal code disk A43. The metal code disk A43, the transmitting coil A, the receiving coil array A and the signal processing circuit A constitute an eddy current encoder A.

[0040] The rotor hub 222 is also provided with a plurality of fan-shaped recesses 2221 at equal intervals along the circumference, so that the rotor hub 222 forms a metal code disk B. The control circuit board is provided with a transmitting coil B, a receiving coil array B and a signal processing circuit B that cooperate with the metal code disk B. The metal code disk B, the transmitting coil B, the receiving coil array B and the signal processing circuit B constitute an eddy current encoder B.

[0041] The above structure realizes in-situ integration of dual eddy current encoders: a fan-shaped concave block is machined in the rotor hub to form a metal code disk B, realizing non-contact position detection at the motor end; a steel wheel is integrated at the output end through the inner ring of the bearing, and a metal code disk A is set at the end of the output hollow tube; the two sets of eddy current encoders interact directly with the control circuit board without independent packaging, completely solving the problem of multi-sensor wiring.

[0042] The housing of this invention also includes a brake assembly, which employs an electromagnetic adsorption brake, comprising a brake stator 24 fixed to the end face of the housing and a brake rotor 25 fixed to the rotor hub 22. The aforementioned brake assembly structure enables rapid response and power-off self-locking, releasing the brake instantly upon power-on to meet high-dynamic start-stop requirements; and automatically locking the shaft upon power loss to enhance safety.

[0043] The wave generator includes an elliptical hub 31 and a flexible bearing 32. The elliptical hub 31 is fixed to the rotating shaft 221, and the flexible bearing 32 is disposed between the flexible wheel 33 and the elliptical hub 31. The combination of the elliptical hub 31 and the flexible bearing 32 ensures uniform elastic deformation of the flexible wheel 33, reducing vibration and noise; the flexible bearing 32 withstands radial deformation force, improving the lifespan of the wave generator.

[0044] This invention integrates multiple layers of components—motor, sensor, brake, and reducer—resulting in extremely high axial space utilization. Furthermore, by directly integrating strain gauges into the flexible wheel, it achieves high-bandwidth torque feedback, realizing a closed-loop force control system and providing a foundation for precision force control (such as in collaborative robots). The built-in strain gauges detect torque, and the dual eddy current encoders detect rotational speed at the input and output terminals, avoiding errors introduced by external sensors.

[0045] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A high-density force-controlled joint module, characterized by: The system includes a housing, a PCB motor assembly, and a harmonic reducer. The PCB motor assembly includes a PCB motor stator (21) and a PCB motor rotor. The PCB motor stator (21) is fixed to one end face of the housing. The PCB motor rotor includes a shaft (221), a rotor hub (222), and a magnetic ring (23). The rotor hub (222) is located at one end of the shaft (221), and the magnetic ring (23) is fixed to the end face of the rotor hub (222) and faces the PCB motor stator (21). The shaft (221) is rotatably connected to the main housing (11) via a bearing (5). The harmonic reducer includes a wave generator, a flexible wheel (33), and an output shaft. The wave generator is fixed at the other end of the rotating shaft (221). One end of the flexible wheel (33) is fixed to the housing, and the other end is sleeved on the outside of the wave generator. The output bearing includes an inner bearing ring (35) and an outer bearing ring (34). The outer bearing ring (34) is fixed to the housing. A steel wheel is integrated on the inner bearing ring (35), and the steel wheel is sleeved on the outside of the flexible wheel (33) and drives the flexible wheel (33) with staggered teeth. The connecting beam surface of the inner and outer rings of the flexible wheel (33) is also provided with a strain elastic body (331), and multiple strain elastic bodies (331) form a Wheatstone full-bridge circuit that converts small deformations into weak voltage signals, and is connected to the control circuit board through a signal processing circuit board. The outer end face of the inner ring (35) of the output bearing is also fixed with an output disk (41). The output disk (41) has a through hole in the middle and an output hollow tube (42) is connected to the through hole. The output hollow tube (42) passes through the harmonic reducer and the PCB motor assembly and extends to the control circuit board. The housing includes a main housing (11) with a convex cross-section and a cover plate (12) fixed to one end of the main housing (11). The control circuit board is fixed in the receiving cavity formed by the main housing (11) and the cover plate (12). The cover plate (12) has a through hole in the middle and a convex ring A is provided on the inner side of the cover plate (12). The output hollow tube (42) has a convex ring B at its end. The cross sections of the convex ring A and the convex ring B are respectively concave and convex, and they are fitted together with a gap after being inserted. The end of the output hollow tube (42) is also provided with a metal code disk A (43) which is fixed thereon. The control circuit board is provided with a transmitting coil A, a receiving coil array A and a signal processing circuit A that cooperate with the metal code disk A (43). The metal code disk A (43), the transmitting coil A, the receiving coil array A and the signal processing circuit A constitute an eddy current encoder A. The rotor hub (222) is also provided with a plurality of fan-shaped recesses (2221) at equal intervals along the circumference, so that the rotor hub (222) forms a metal code disk B. The control circuit board is provided with a transmitting coil B, a receiving coil array B and a signal processing circuit B that cooperate with the metal code disk B. The metal code disk B, the transmitting coil B, the receiving coil array B and the signal processing circuit B constitute an eddy current encoder B.

2. The high-density force-controlled joint module according to claim 1, characterized in that, One end of the main housing (11) is a connecting part, the rotating shaft (221) passes through the connecting part and is rotatably connected to the connecting part through the bearing (5), and the flexible wheel (33) is sleeved outside the connecting part and leaves a gap with the connecting part.

3. The high density force controlled joint module of claim 1, wherein, It also includes a brake assembly, which employs an electromagnetic adsorption brake, comprising a brake stator (24) fixed to the end face of the housing and a brake rotor (25) fixed to the rotor hub (222).

4. The high-density force-controlled joint module of claim 1, wherein, The wave generator includes an elliptical hub (31) and a flexible bearing (32). The elliptical hub (31) is fixed to the rotating shaft (221), and the flexible bearing (32) is disposed between the flexible wheel (33) and the elliptical hub (31).

5. The high density force controlled joint module of claim 1, wherein, The bearing (5) is a double-row angular contact bearing.

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