A two-degree-of-freedom joint module suitable for small robots

Abstract

This invention discloses a dual-degree-of-freedom joint module suitable for small robots, relating to the field of robot joint drive technology. The module includes two independent drive units, each comprising a frame, a frameless torque motor, a rotor carrier, and a planetary gear reducer. The stator of the frameless torque motor is fixed to the frame, and the outer rotor is fixedly connected to the rotor carrier. An input gear is mounted on the rotor carrier. The planetary gear reducer includes a first-stage planetary gear, a first-stage planetary carrier, a second-stage planetary gear, a second-stage planetary carrier, and a housing; the second-stage planetary carrier also serves as the output shaft. The input gear directly meshes with the first-stage planetary gear. The outer rotor drives the input gear to rotate through the rotor carrier, thereby driving the planetary gear reducer, and power is output through the output shaft. The two drive units are independently controlled, achieving independent movement with two degrees of freedom. This invention significantly reduces the size of the joint module and improves power density and motion flexibility through the compact integration and direct drive of the motor and reducer.

Description

Technical Field

[0001] This invention relates to the field of robot joint drive technology, and in particular to a two-degree-of-freedom joint module suitable for small robots. Background Technology

[0002] Small biomimetic robots (such as quadrupedal, bipedal, and variable-configuration robots) place stringent demands on the size, weight, and power density of their joint drive modules. Existing joint modules typically aim to meet the high torque output requirements of large robots, employing large-volume drive structures. This results in a large overall module size and weight, making it difficult to adapt to the lightweight and miniaturization needs of small robots and severely limiting joint mobility. To address the size issue, some existing solutions use a side-by-side arrangement of the motor and reducer, but individual joint modules still suffer from insufficient volume compression and low power density. More importantly, existing modules, while compactly integrated with multiple degrees of freedom, lack independent motion control capabilities, typically only achieving single-degree-of-freedom drive and unable to simultaneously control two degrees of freedom independently. This makes it difficult to meet the needs of multi-joint cooperative motion and complex motion scenarios in small robots. Furthermore, the transmission structure between the motor and reducer in existing technologies is often complex, further increasing the overall size and reducing transmission efficiency.

[0003] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-degree-of-freedom joint module suitable for small robots, so as to solve the problems existing in the prior art, and enable the joint module to achieve high power density dual-degree-of-freedom independent motion output while significantly reducing the overall size and weight.

[0005] To achieve the above objectives, the present invention provides the following solution: A two-DOF joint module suitable for small robots includes two independent drive units, each drive unit comprising: frame; A frameless torque motor includes a stator fixed to the frame and a rotatable outer rotor; A rotor frame is fixedly connected to the outer rotor, and an input gear is provided on the rotor frame; A planetary gear reducer includes a first-stage planetary gear, a first-stage planetary carrier, a second-stage planetary gear, a second-stage planetary carrier, and a housing, wherein the second-stage planetary carrier also serves as the output shaft; The input gear meshes with the first-stage planetary gear, and the outer rotor drives the input gear to rotate through the rotor frame, thereby driving the planetary gear reducer, and outputting power through the output shaft; The two drive units are controlled independently to achieve independent motion with two degrees of freedom.

[0006] In an exemplary embodiment, the planetary gear reducer is a two-stage planetary gear reducer, the inner wall of the housing is provided with a gear ring, the first-stage planetary gear meshes with the input gear and the gear ring on the inner wall of the housing respectively, and the second-stage planetary gear meshes with the central sun gear on the first-stage planet carrier and the gear ring on the inner wall of the housing respectively.

[0007] In an exemplary embodiment, the rotor frame is rotatably supported on the frame by at least one bearing, the inner ring of the bearing engaging with the shaft portion of the rotor frame, and the outer ring of the bearing being fixed to the frame.

[0008] In an exemplary embodiment, the rotor frame is provided with a groove, and a detection magnetic sheet is fixed in the groove; a drive plate housing is provided on the side of the rotor frame away from the frame, the drive plate housing is connected to the frame through a drive plate support member, a drive control board is fixed on the drive plate housing, and a magnetic encoder is integrated on the drive control board. The magnetic encoder is arranged opposite to the detection magnetic sheet and is used to detect the speed and position of the outer rotor.

[0009] In one exemplary embodiment, an encoder is provided at the output shaft end of the planetary gear reducer. The encoder is fixedly connected to the frame via an encoder bracket and is used to detect the position of the output shaft.

[0010] In an exemplary embodiment, the stator of the frameless torque motor is fixedly connected to the frame via an interference fit.

[0011] In one exemplary embodiment, the outer rotor is fixedly connected to the rotor frame by adhesive bonding, and the input gear is fixedly connected to the rotor frame by interference fit.

[0012] In one exemplary embodiment, the planetary gear reducer further includes an input terminal, which is fixedly connected to the frame and sleeved on the outside of the input gear to suppress axial movement of the gear set.

[0013] In one exemplary embodiment, a reducer shim is provided between the input terminal and the first-stage planetary gear to reduce friction.

[0014] In one exemplary embodiment, the two drive units are arranged side by side, and their respective output shafts can be connected to external linkages to adapt to the joint drive requirements of robots with different configurations.

[0015] The present invention achieves the following technical effects compared to the prior art: 1. Highly compact integration, significantly reducing size: By fixing the stator of the frameless torque motor to the frame, and the outer rotor to the rotor frame, and directly setting the input gear to mesh with the first-stage planetary gear of the planetary gear reducer on the rotor frame, the additional coupling or intermediate transmission shaft is eliminated, achieving a compact axial layout of the motor and reducer, and greatly reducing the overall size of the joint module.

[0016] 2. High power density output: The frameless torque motor and planetary gear reducer are directly connected for transmission. The outer rotor directly drives the input gear. The power transmission path is short and the loss is small. High power density drive output can be achieved in a small size structure, which meets the dual requirements of miniaturization and high output of small robots for drive units.

[0017] 3. Independent Dual-DOF Control for Flexible Motion: Two independent drive units are configured, each capable of independently controlling the movement of its output axis, achieving a modular design for the dual-DOF joint module. The two output axes can be controlled independently without interference, allowing for flexible integration with external linkages to meet the diverse motion requirements of different robot configurations (such as quadrupeds, bipeds, and variable-configuration robots), significantly improving the joint module's adaptability and motion flexibility.

[0018] 4. High transmission efficiency and stable output: The input gear meshes directly with the first-stage planetary gear. The rotational power of the outer rotor is transmitted to the output shaft step by step through the rotor frame, input gear, and planetary gear reducer. The gear meshing transmission method reduces power loss and improves output efficiency and operational reliability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a two-degree-of-freedom joint module suitable for small robots, as disclosed in a specific embodiment of the present invention. Figure 2 for Figure 1 The main view; Figure 3 for Figure 1 Exploded view of the frameless torque motor module; Figure 4 for Figure 1Exploded view of the planetary gear reducer module; Figure 5 for Figure 2 A sectional view; in: 1. Frameless torque motor module; 101. Frame; 102. Bearing; 103. Bearing; 104. Frameless torque motor stator; 105. Frameless torque motor outer rotor; 106. Rotor frame; 107. Reducer input gear; 108. Detection magnetic sheet; 109. Drive board support; 110. Motor drive main control board; 111. Drive board housing; 2. Gearbox module; 201. Input terminal; 202. Gearbox gasket; 203. Gearbox housing; 204. First-stage planetary gear; 205. First-stage planetary carrier; 206. Second-stage planetary gear; 207. Second-stage planetary carrier; 208. Gearbox encoder frame; 209. Encoder. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The purpose of this invention is to provide a dual-degree-of-freedom joint module suitable for small robots, so as to solve the problems existing in the prior art, and enable the joint module to achieve high power density dual-degree-of-freedom independent motion output while significantly reducing the overall size and weight.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Please refer to Figures 1 to 5 This embodiment provides a dual-degree-of-freedom joint module suitable for small robots, comprising two independent drive units, each capable of independently outputting rotational power. The two units are arranged side-by-side or mounted on the same housing or base according to the robot's joint layout requirements to achieve independent movement of the two degrees of freedom. Each drive unit mainly consists of a frameless torque motor module 1 and a planetary gear reducer module 2. Taking one drive unit as an example, its specific structure is as follows: The frame 101, serving as the mounting base for the entire drive unit, can be precision-machined from aluminum alloy or steel, possessing sufficient structural rigidity to support the motor and reducer. The stator 104 of the frameless torque motor 1 is fixed to the inner wall of the frame 101 or a dedicated mounting surface via an interference fit. This interference fit ensures that the stator does not undergo relative displacement under long-term vibration conditions. Alternatively, screw-assisted tightening or adhesive bonding can be used; these are mature existing technologies and will not be elaborated upon here. The outer rotor 105 of the frameless torque motor is a rotatable ring structure with permanent magnets mounted on its inner side, interacting with the electromagnetic field generated by the stator 104 to produce torque.

[0025] The rotor frame 106 is a rotating part with one open end or a journal. Its outer circumferential surface or end face is fixedly connected to the outer rotor 105 by adhesive bonding. The adhesive bonding uses high-temperature resistant and high-strength structural adhesive to ensure that the rotational power of the outer rotor is reliably transmitted to the rotor frame. A shaft is provided at the center of the rotor frame 106, which is rotatably supported on the frame 101 by two bearings 102 and 103 (the specific support structure will be described in detail later). An input gear 107 is provided at one end of the rotor frame 106 near the frame 101 or at the shaft end. The input gear and the rotor frame 106 are preferably separate structures and fixed by interference fit to facilitate machining and heat treatment; in another embodiment, the input gear 107 can also be integrally formed with the rotor frame 106, as long as it can be ensured that there is no relative rotation between the two.

[0026] The planetary gear reducer 2 adopts a two-stage planetary gear transmission, mainly comprising a first-stage planetary gear 204, a first-stage planetary carrier 205, a second-stage planetary gear 206, a second-stage planetary carrier 207 which also serves as an output shaft, and a housing 203. The inner wall of the housing 203 is machined with an internal gear ring, serving as the orbital track for the planetary gears. The input gear 107, acting as the sun gear, passes through the reducer's input terminal 201 and directly meshes with the first-stage planetary gear 204. When the outer rotor 105 rotates under the drive of the motor, it drives the rotor carrier 106 to rotate synchronously, thereby driving the input gear 107 to rotate. The input gear 107 drives the first-stage planetary gear 204 to rotate on its own axis and revolve around the input gear. The revolution of the first-stage planetary gear 204 drives the first-stage planetary carrier 205 to rotate. A central sun gear is fixed on the first-stage planetary carrier 205, which meshes with the second-stage planetary gear 206, driving the second-stage planetary gear 206 to rotate on its own axis and revolve around the input gear. Ultimately, this drives the second-stage planetary carrier 207, which also serves as an output shaft, to rotate, outputting the reduced-speed and increased-torque power from its output shaft end. Through the above transmission path, the high-speed, low-torque motion of the motor is converted into low-speed, high-torque output. At the same time, the entire drive unit is highly compact in the axial direction, and its volume is much smaller than that of the traditional scheme where the motor and reducer are arranged side by side.

[0027] In this embodiment, the two drive units are independent of each other and are controlled by their respective motor drive main control boards 110, enabling independent speed, position, and torque control, thus forming a two-degree-of-freedom joint module. The output shaft of this module can be configured with a linkage mechanism as needed to drive the hip joint, shoulder joint, or other parts of the small robot that require two independent degrees of freedom. Compared with the prior art, this embodiment achieves independent two-degree-of-freedom motion in a very small space by integrating a frameless torque motor and a planetary gear reducer into one unit and setting up two independent units, significantly improving the joint flexibility and structural compactness of the small robot.

[0028] In this embodiment, the outer casing 203 is a cylindrical part with a high-precision internal gear ring machined on its inner wall. The number of first-stage planetary gears 204 is typically three (or four, to achieve load balancing, which is a conventional design in the planetary gear field), evenly distributed and mounted on the planetary gear shafts of the first-stage planetary carrier 205. Each first-stage planetary gear 204 simultaneously meshes with both the input gear 107 and the internal gear ring of the outer casing 203. When the input gear 107 rotates, the first-stage planetary gears 204 rotate under its action. Simultaneously, since the outer casing 203 remains stationary, the revolution of the first-stage planetary gears 204 drives the first-stage planetary carrier 205 to rotate in the same direction. A sun gear is integrally or rigidly connected to the center of the first-stage planetary carrier 205, and this sun gear meshes with the second-stage planetary gear 206. The second-stage planetary gears 206 are also evenly distributed and mounted on the planetary gear shafts of the second-stage planetary carrier 207, and each second-stage planetary gear 206 simultaneously meshes with both the central sun gear on the first-stage planetary carrier 205 and the internal gear ring of the outer casing 203. The output shaft is centrally located on the second-stage planetary carrier 207, extending from the central hole of the end cover of the housing 203. Through the reduction of speed using two stages of planetary gears, a large reduction ratio, typically between 10:1 and 100:1, can be achieved while maintaining smooth transmission and low backlash. This two-stage planetary gear reducer has a compact structure, with all gears enclosed within the housing 203, providing excellent dustproof and lubrication performance. As a mature technology, the gear material can be carburized and quenched steel, and the internal gear ring can be directly machined onto the inner wall of the housing or pressed into the housing as a separate gear ring; these are all conventional choices in the field.

[0029] To achieve smooth, low-friction rotation of the rotor frame 106, this embodiment employs at least one bearing 102 or 103 for support. Specifically, bearing mounting holes are machined on the frame 101, and the outer rings of bearings 102 and 103 are fixed within these mounting holes via an interference fit or a transition fit. The bearing type is preferably a deep groove ball bearing to withstand radial loads and a certain axial load. The shaft portion of the rotor frame 106 (i.e., the end carrying the input gear 107) passes sequentially through the inner rings of bearings 102 and 103, with a transition fit such as H7 / h6 between them. This ensures free rotation of the rotor frame while preventing excessive clearance that could cause radial runout. The axial distance between the two bearings is determined based on the length of the shaft portion of the rotor frame 106; a larger distance results in better support rigidity. The inner rings of the bearings are axially positioned by the shaft shoulder and retaining ring on the rotor frame 106, while the outer rings are fixed by the steps and bearing caps on the frame 101. As a conventional solution in the prior art, the fit between the bearing and the frame 101, and between the bearing and the rotor frame 106, as well as the lubrication method such as adding grease, are common knowledge in the field of mechanical design and will not be elaborated here. Through this bearing support structure, the rotor frame 106 can rotate with extremely low frictional resistance under the drive of the motor, thereby ensuring power transmission efficiency while reducing vibration and noise.

[0030] To achieve precise detection of the rotational speed and position of the external rotor 105, thereby enabling closed-loop control of the motor, this embodiment integrates a magnetic detection structure on the rotor frame 106. Specifically, as follows... Figure 5 As shown, a groove is machined on the end face of the rotor frame 106 facing the drive plate housing 111, and a detection magnetic sheet 108 is fixed in the groove. The detection magnetic sheet 108 is made of permanent magnet, and its shape and magnetization method can be implemented in various ways, as long as it can generate a periodic magnetic field that changes with the rotor angle at the position of the magnetic encoder. For example, in one embodiment, the detection magnetic sheet 108 adopts a disk-shaped structure with a certain thickness, and multiple pairs of alternating magnetic poles (i.e., NSNS...) are provided along the circumferential direction on its circular end face facing the drive control plate 110. This magnetization method is called axial magnetization or end face multi-pole magnetization, and the magnetic encoder is installed facing the end face to detect changes in the axial magnetic field. In another embodiment, the detection magnetic sheet 108 can also adopt a ring structure and be radially magnetized on its circumferential surface. In this case, the magnetic encoder is located on the radially outer side of the detection magnetic sheet. Regardless of the specific form, the detection magnetic sheet 108 is fixed in the groove of the rotor frame 106 with high-strength adhesive and rotates together with the rotor frame.

[0031] A drive plate housing 111 is provided on the side of the rotor frame 106 away from the frame 101. The drive plate housing 111 is fixedly connected to the frame 101 via a drive plate support member 109. The drive plate support member 109 can be a metal or plastic columnar support rod, with both ends connected to the frame 101 and the drive plate housing 111 respectively by screws; or, the drive plate support member 109 can also be an integrally formed shell-shaped bracket, as long as it can stably support the drive plate housing 111 on the outside of the rotor frame 106.

[0032] A motor drive main control board 110 is fixed on the drive board housing 111. This main control board integrates a magnetic encoder chip (e.g., a commercial magnetic encoder using the Hall effect or anisotropic magnetoresistive (AMR) principle, such as the AS5047 series). The magnetic encoder and the detection magnetic plate 108 are positioned opposite each other, with a certain air gap between them. When the rotor frame 106 rotates, the spatial magnetic field generated by the detection magnetic plate 108 changes accordingly. After the magnetic encoder detects the change in magnetic field angle, the processor on the main control board calculates the result to obtain the rotational speed and absolute position (angle) of the outer rotor 105 in real time. Compared with traditional photoelectric encoders, this magnetic encoding scheme has advantages such as small size, vibration resistance, and no need for gratings, making it particularly suitable for the compact space of small robot joints. It should be noted that the power supply, signal processing, and communication circuits between the magnetic encoder chip and the main control chip are all mature existing technologies and will not be described in detail in this embodiment.

[0033] In addition to detecting the position of the motor rotor, this embodiment further detects the position of the reducer output shaft to achieve high-precision closed-loop control of the joint end position. For example... Figure 5 As shown, a reducer encoder frame 208 is provided on the outside of the reducer housing 203. One end of the reducer encoder frame 208 is fixed to the frame 101 by screws (or fixed to the housing 203, as long as it remains stationary relative to the frame), and the other end is fixed with an encoder 209. The encoder 209 can be a magnetic encoder or an optical encoder. For a magnetic encoder, a corresponding magnetic ring needs to be installed on the output shaft; for an optical encoder, a grating code disk needs to be installed on the output shaft. Since the output shaft is reduced by two stages of planetary gears, its speed is low and its torque is high. The encoder 209 can provide a high-resolution absolute position signal, thereby forming a double closed-loop control with the magnetic encoder on the motor side: the inner loop is the motor rotor speed loop, and the outer loop is the output shaft position loop. The combination of the two can significantly improve the positioning accuracy and anti-interference capability of the joint movement. As a mature existing technology, the communication between the encoder and the main control board can use SPI, ABZ incremental signals, or SSI absolute signals, etc. Those skilled in the art can choose according to actual needs, which will not be elaborated here.

[0034] The stator 104 of the frameless torque motor is typically made of laminated silicon steel sheets, with a smooth cylindrical outer circumference. To ensure reliable fixation between the stator and the frame 101, this embodiment employs an interference fit. Specifically, the inner diameter of the hole on the frame 101 used to mount the stator is slightly smaller than the outer diameter of the stator 104. Assembly is completed through hot fitting (heating the frame 101 to a certain temperature and then inserting the stator 104) or cold pressing (freezing the stator 104 and then pressing it into the frame 101). The interference amount is calculated based on the material, diameter, and stress requirements. The interference fit generates positive pressure between the stator and the frame, relying on friction to resist the electromagnetic torque reaction force during motor operation. No additional screws or keys are required, thus saving axial space. In cases requiring further tightening, anaerobic adhesive can be filled between the stator end face and the frame step, but the interference fit itself is sufficient to meet the operating requirements of most small robot joints; this is a mature existing technology.

[0035] The outer rotor 105 is typically a thin-walled cup-shaped structure with permanent magnets bonded to its inner wall, and its outer wall needs to be fixed to the rotor frame 106. This embodiment uses an adhesive connection: a high-strength structural adhesive (such as epoxy resin adhesive, Loctite E-120HP is recommended) is applied to the outer circumferential surface or end face of the rotor frame 106, then the outer rotor 105 is fitted and pressed tightly, and cured at room temperature or under heating conditions. Adhesive bonding does not cause stress concentration and can uniformly transmit torque. As an alternative, radial screw locking can be used, but screws increase imbalance and volume, so adhesive bonding is preferred. The input gear 107 is fixed to the shaft end of the rotor frame 106 with an interference fit, similar to the stator interference fit. Since the input gear bears a large torque, the interference fit ensures no relative slippage. In practice, the input gear 107 can be frozen and then pressed into the shaft end of the rotor frame 106, or the shaft end of the rotor frame 106 can be heated and then fitted onto the input gear 107. To ensure coaxiality during assembly, the rotor frame shaft end and the inner hole of the input gear require precision machining with a surface roughness Ra≤0.8μm. The interference fit is determined based on the transmitted torque calculation. The aforementioned bonding and interference fit are standard processes in the field of mechanical transmission, and those skilled in the art can select the appropriate type based on conventional parameters.

[0036] To suppress axial movement of the gear set and seal the internal space of the reducer, this embodiment provides an input terminal 201 at the input end of the planetary gear reducer. For example... Figure 5As shown, the input terminal 201 is located inside the reducer housing 203, sleeved on the outside of the input gear 107, and fixedly connected to the end faces of the reducer housing 203 and the frame 101 by screws. A gap is left between the inner hole of the input terminal 201 and the journal of the input gear 107, preventing contact with rotating parts; its end face faces the end face of the first-stage planetary gear 204, limiting the axial movement of the first-stage planetary gear 204 and preventing gear disengagement or excessive axial displacement. The input terminal 201 can be made of aluminum alloy or engineering plastic to reduce weight. As per existing technology, the specific dimensions of the input terminal 201 should ensure concentricity with the input gear to ensure installation accuracy.

[0037] To further reduce friction between the input terminal 201 and the first-stage planetary gear 204 (although they do not normally contact each other, assembly errors or axial impacts may cause momentary contact), this embodiment provides a reducer shim 202 between the input terminal 201 and the first-stage planetary gear 204. This shim is made of a self-lubricating material, such as polytetrafluoroethylene (PTFE) or copper-based graphite composite material, and has a low coefficient of friction and wear resistance. The shim is annular and fitted onto the journal of the input gear 107, with one side tightly against the end face of the input terminal and the other side maintaining a very small gap with the end face of the first-stage planetary gear 204 or acting as a buffer under pressure. This shim prevents direct metal-to-metal contact from causing wear or noise, and can also compensate for axial dimensional tolerances to some extent. Alternatively, a solid lubricating coating can be directly applied to the end face of the input terminal 201, but the replaceability of the independent shim is better.

[0038] Two independent drive units are fixed side-by-side to the robot's skeleton or joint base, with their output shafts facing the same or opposite directions (depending on the specific configuration). Each output shaft has a connecting flange or keyway at its end for connecting external links. For example, in the hip joint application of a small quadruped robot, the output shaft of one drive unit connects to the thigh link, and the output shaft of the other drive unit connects to the lateral swing link. By controlling the rotation angle and speed of the two motors respectively, the two degrees of freedom of the hip joint—flexion / extension and abduction / adduction—can be achieved. For bipedal robots, this can be similarly configured at the ankle or shoulder joint. Because the output shafts are reduced by planetary gears, they have sufficient holding torque, maintaining the joint position even when the motors are powered off, thus improving the robot's static stability. It should be noted that the specific shape, length, and joint arrangement of the external links fall within the scope of robot configuration design. Those skilled in the art can freely design them according to the kinematic requirements of the target robot. The dual-degree-of-freedom joint module provided in this embodiment is only a standardized drive module and does not limit the specific form of the links.

[0039] The following section will further elaborate on the beneficial effects of the entire two-degree-of-freedom joint module by examining its dynamic working process.

[0040] When a certain degree of freedom of motion is required, the corresponding motor drive main control board 110 supplies three-phase current to the stator 104 winding of the frameless torque motor 1 according to the host computer command (such as target position or speed), generating a rotating magnetic field. This magnetic field interacts with the permanent magnet on the outer rotor 105, generating electromagnetic torque and driving the outer rotor 105 to rotate. The outer rotor 105 drives the rotor frame 106 to rotate through bonding, and the input gear 107 on the rotor frame 106 rotates accordingly. The input gear 107 inputs power to the planetary gear reducer 2, and after two stages of reduction and torque amplification by the first-stage planetary gear 204 and the second-stage planetary gear 206, the low-speed, high-torque rotational motion is finally output by the output shaft. Throughout the process, the detection magnetic sheet 108 and the magnetic encoder on the motor side detect the rotor speed and position in real time, and the main control board adjusts the current accordingly to achieve speed closed loop or position closed loop; at the same time, the encoder 209 at the output shaft end detects the actual output position and further corrects the control quantity, forming a high-precision dual closed-loop control. Because the entire transmission chain has no additional couplings or intermediate drive shafts, all gears mesh directly, resulting in extremely low power loss and extremely high transmission efficiency. Simultaneously, the axial dimension is compressed to the sum of the thicknesses of the motor and reducer, leading to a significantly higher power density than traditional solutions.

[0041] When another degree of freedom of motion is required, the other independent drive unit operates independently in exactly the same way, without interfering with each other. Since the two drive units are structurally completely independent, connected only by a common frame or base, they can achieve different motion trajectories and speeds, thus giving the robot joints two independent rotational degrees of freedom. This modular design allows robot developers to quickly build multi-degree-of-freedom biomimetic robots simply by selecting the dual-degree-of-freedom joint module of this invention, without needing to design complex integrated drive and transmission structures themselves, significantly shortening the development cycle and improving system reliability.

[0042] In the description of this invention, it should be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used only for the convenience of describing the invention, and do not imply or require that the device or element referred to must have a specific orientation or construction method, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish the objects of description and should not be construed as limiting importance or order, and the features defined by such terms may explicitly or implicitly include one or more of those features. Unless otherwise stated, "a plurality of" in the description of this invention refers to two or more.

[0043] The terms "installation," "connection," and "joining" should be interpreted broadly, unless otherwise explicitly defined, to include, but are not limited to, fixed connections, detachable connections, or integrally formed connections; mechanical or electrical connections; direct connections or indirect connections via an intermediate medium; and internal communication between two components. Those skilled in the art can understand their meaning based on the specific technical solution. The fixed connections involved in this invention, unless otherwise stated, include both detachable fixed connections (such as bolt and screw connections) and non-detachable fixed connections (such as riveting and welding), and may also include integral structures achieved through an integral forming process (such as casting) (except where integral forming is clearly not feasible).

[0044] Unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes cover states or shapes that are similar to, close to, or adjacent to them.

[0045] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured using a one-piece molding process.

[0046] It should be noted that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read them, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0047] In the embodiments of this application, the same reference numerals are used to denote the same component or part.

[0048] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0049] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A two-degree-of-freedom joint module suitable for small robots, characterized in that: It includes two independent drive units, each of which contains: Rack (101); The frameless torque motor (1) includes a stator (104) fixed to the frame (101) and a rotatable outer rotor (105). The rotor frame (106) is fixedly connected to the outer rotor (105), and the rotor frame (106) is provided with an input gear (107). The planetary gear reducer (2) includes a first-stage planetary gear (204), a first-stage planetary carrier (205), a second-stage planetary gear (206), a second-stage planetary carrier (207), and a housing (203), wherein the second-stage planetary carrier (207) also serves as the output shaft; The input gear (107) meshes with the first-stage planetary gear (204), and the outer rotor (105) drives the input gear (107) to rotate through the rotor frame (106), thereby driving the planetary gear reducer and outputting power through the output shaft; The two drive units are controlled independently to achieve independent motion with two degrees of freedom.

2. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The planetary gear reducer is a two-stage planetary gear reducer. The inner wall of the housing (203) is provided with a gear ring. The first-stage planetary gear (204) meshes with the input gear (107) and the gear ring on the inner wall of the housing (203) respectively. The second-stage planetary gear (206) meshes with the central sun gear on the first-stage planet carrier (205) and the gear ring on the inner wall of the housing (203) respectively.

3. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The rotor frame (106) is rotatably supported on the frame (101) by at least one bearing (102, 103), the inner ring of the bearing (102, 103) is engaged with the shaft portion of the rotor frame (106), and the outer ring of the bearing (102, 103) is fixed to the frame (101).

4. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The rotor frame (106) is provided with a groove, and a detection magnetic sheet (108) is fixed in the groove; a drive plate housing (111) is provided on the side of the rotor frame (106) away from the frame (101), the drive plate housing (111) is connected to the frame (101) through a drive plate support (109), a drive control board (110) is fixed on the drive plate housing (111), and a magnetic encoder is integrated on the drive control board (110). The magnetic encoder is arranged opposite to the detection magnetic sheet (108) and is used to detect the speed and position of the outer rotor (105).

5. The dual-degree-of-freedom joint module according to claim 1, characterized in that: An encoder (209) is provided at the output shaft end of the planetary gear reducer. The encoder (209) is fixedly connected to the frame (101) through an encoder frame (208) and is used to detect the position of the output shaft.

6. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The stator (104) of the frameless torque motor is fixedly connected to the frame (101) by an interference fit.

7. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The outer rotor (105) is fixedly connected to the rotor frame (106) by adhesive bonding, and the input gear (107) is fixedly connected to the rotor frame (106) by interference fit.

8. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The planetary gear reducer also includes an input terminal (201), which is fixedly connected to the frame (101) and sleeved on the outside of the input gear (107) to suppress axial movement of the gear set.

9. The dual-degree-of-freedom joint module according to claim 8, characterized in that: A reducer shim (202) is provided between the input terminal (201) and the first-stage planetary gear (204) to reduce friction.

10. The dual-degree-of-freedom joint module according to claim 1, characterized in that: The two drive units are arranged side by side, and their respective output shafts can be connected to external linkages to adapt to the joint drive requirements of robots with different configurations.

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