Dual encoder outer rotor joint module and method of use

Abstract

The application relates to the technical field of robot joint motors and encoders, in particular to a double-encoder outer rotor joint module and a use method thereof. The double-encoder outer rotor joint module comprises a high-speed end inductive encoder module, which comprises an inductive rotor plate connected with a rotor and an inductive coil plate connected with a drive-encoder integrated plate, wherein the inductive coil plate is arranged on the side of the drive-encoder integrated plate facing the inductive rotor plate, and the inductive coil plate and the inductive rotor plate are matched to obtain an absolute mechanical angle value of the high-speed end; and a low-speed end magnetic encoder module, which comprises an excitation magnetic ring connected with the output end of a speed reducer and a magnetic sensitive element connected with the drive-encoder integrated plate. The high-speed end adopts an inductive encoder, which fundamentally solves the interference problem of a strong magnetic field of an outer rotor motor on an encoder and ensures high-precision control of a FOC current loop; and the low-speed end adopts a magnetic encoder to realize absolute position feedback of the output end at a lower cost and eliminate the influence of transmission errors of the speed reducer.

Description

Technical Field

[0001] This invention relates to the field of robot joint motors and encoders, specifically to a dual-encoder external rotor joint module and its usage method. Background Technology

[0002] Exoskeleton-assisted robots and medical exoskeleton-assisted robots place stringent requirements on joint drive modules: achieving high torque density output within a compact size, while possessing high-precision position control capabilities and reliability under complex working conditions. External rotor brushless DC motors, due to their compact structure and high torque density, are widely used in these applications.

[0003] Traditional external rotor joint modules typically have a single encoder configured only at the high-speed end of the motor or the low-speed end of the reducer. If only a high-speed absolute encoder is configured, theoretically the low-speed angle can be calculated through the transmission ratio. However, factors such as gear backlash, transmission errors, and elastic deformation in the reducer can cause a deviation between the actual output position and the expected control position, making it difficult to meet high-precision position control requirements; the output position is lost when the motor is powered off. If only a low-speed encoder is configured, although the output position can be directly obtained, eliminating backlash and gear errors, the presence of reducer backlash and elasticity, along with the low speed resolution at low speeds, prevents the control system from quickly sensing dynamic changes at the motor end, easily leading to oscillations and control instability.

[0004] Some solutions employ magnetic encoders at both high and low speeds. However, the external rotor motor itself is a strong magnetic field source, with its rotor containing permanent magnets arranged in alternating N and S poles, generating a strong rotating magnetic field during operation. The high-speed magnetic encoder, located close to the motor body, is highly susceptible to interference from this low-frequency magnetic field, leading to decreased angle calculation accuracy. This accuracy loss directly impacts the current loop control accuracy of the FOC (Field Oriented Control) algorithm, resulting in increased motor heating, torque ripple, and significant current noise. Using magnetic encoders at both high and low speeds means the signal generators (magnets and heads) are placed close together due to size and weight considerations. If, to accommodate the large shaft misalignment and large motor skew caused by the high flexibility of exoskeleton-like devices, a strong single-pole magnet is used, the encoder recognition at both speeds will interfere with each other. In particular, the interference from the high-speed encoder to the low-speed encoder will be inconsistent across each revolution due to the reducer's speed ratio, making it difficult to compensate for using pre-set algorithms. If multiple pairs of magnets are designed to reduce this interference, and simulation optimization is performed on the spatial magnetic circuit, the magnetism of the magnets will be greatly reduced, and the range of signal recognition and allowable motion angle will be reduced, which will not meet the high flexibility application requirements of this product.

[0005] Furthermore, in scenarios involving human-computer interaction, such as medical rehabilitation and sports assistance, the reliability of encoder signals is directly related to operational safety. If a single encoder malfunctions or experiences signal abnormalities, the control system will lose its position reference, potentially leading to unexpected movements. Existing solutions generally lack hardware redundancy verification mechanisms at the encoder level. Summary of the Invention

[0006] In order to solve or at least partially solve the defects or deficiencies of the prior art, the present invention proposes a dual encoder external rotor joint module and its usage method.

[0007] In a first aspect of the present invention, a dual encoder external rotor joint module is provided, comprising:

[0008] The high-speed inductive encoder module includes:

[0009] Inductor rotor plate, connected to the rotor;

[0010] The inductor coil board is connected to the drive and braiding integrated board, and the inductor coil board is located on the side of the drive and braiding integrated board facing the inductor rotor board. The inductor coil board and the inductor rotor board cooperate to obtain the absolute mechanical angle value at the high speed end.

[0011] The low-speed magnetic encoder module includes:

[0012] The excitation magnetic ring is connected to the output end of the reducer;

[0013] The magnetic sensitive element is connected to the integrated drive and braiding board, and the magnetic sensitive element is set on the side of the integrated drive and braiding board facing the inductor rotor board. The magnetic sensitive element works with the excitation magnetic ring to obtain the absolute mechanical angle value at the low speed end.

[0014] As a preferred embodiment of the present invention, the inductor rotor plate has a code track arranged in the circumferential direction on the side facing the inductor coil plate; the inductor coil plate is provided with a transmitting coil and a receiving coil.

[0015] As a preferred embodiment of the present invention, the excitation magnetic ring is a multi-stage excitation magnetic ring; four magnetic sensitive elements are provided, and the four magnetic sensitive elements are arranged in a pairwise differential manner.

[0016] As a preferred embodiment of the present invention, the integrated drive and coding board is further provided with a microcontroller unit, a motor drive circuit and a communication interface.

[0017] As a preferred embodiment of the present invention, it further includes:

[0018] The drive-knitting integrated plate support shell has its first axial end connected to the drive-knitting integrated plate;

[0019] The motor support housing is connected to the second axial end of the drive-coil integrated plate support housing, and the motor support housing is connected to the stator.

[0020] As a preferred embodiment of the present invention, the rotor includes 24 permanent magnets, which are arranged in a circumferential direction with alternating N and S poles in the form of 12 pairs of poles; the stator adopts a 14-turn fractional-slot concentrated winding structure.

[0021] As a preferred embodiment of the present invention, the stator includes a stator coil, the stator coil includes an excitation coil and a plurality of induction coils, the excitation coil includes an outer ring portion and an inner ring portion arranged concentrically, the plurality of induction coils are disposed between the outer ring portion and the inner ring portion of the excitation coil, and the excitation coils maintain a predetermined interval.

[0022] In a second aspect of the present invention, a method of using a dual encoder external rotor joint module is provided, employing the dual encoder external rotor joint module of the first aspect, the method of use comprising:

[0023] The absolute mechanical angle value at the high speed end is obtained based on the inductive encoder module at the high speed end. The cumulative mechanical angle value at the high speed end is obtained based on the absolute mechanical angle value at the high speed end and the cumulative number of rotations at the high speed end. The theoretical mechanical angle value at the low speed end is obtained based on the cumulative mechanical angle value at the high speed end and the reduction ratio.

[0024] The absolute mechanical angle value at the low speed end is obtained based on the low speed end magnetic encoder module, and the angle deviation value is obtained based on the absolute mechanical angle value at the low speed end and the theoretical mechanical angle value at the low speed end.

[0025] Determine if the angle deviation value is greater than the angle deviation threshold. If the angle deviation value is greater than the angle deviation threshold, determine that the encoder signal is abnormal.

[0026] As a preferred embodiment of the present invention, it further includes:

[0027] The cumulative mechanical angle back-calculation value at the high speed end is obtained based on the absolute mechanical angle value at the low speed end and the reduction ratio, and the cumulative number of rotations at the high speed end is determined based on the cumulative mechanical angle back-calculation value at the high speed end.

[0028] In summary, the present invention has the following beneficial effects:

[0029] The high-speed end absolute mechanical angle value is obtained by using a high-speed inductive encoder module. This configuration makes the high-speed encoder immune to low-frequency magnetic fields, highly accurate, and fast-responding. It avoids magnetic field interference from the external rotor permanent magnet, ensures the accuracy of FOC current loop control, reduces motor heating, reduces torque pulsation, and suppresses current noise. The low-speed end absolute mechanical angle value is obtained by using a low-speed magnetic encoder module. This configuration makes the low-speed encoder low-cost, simple to integrate, and can directly feed back the absolute position of the low-speed end, eliminating the influence of reducer error. In the prior art, dual magnetic encoders require a large external rotor joint module to reduce magnetic field interference and improve the accuracy of the encoder. However, the dual encoder in this embodiment of the invention, through the configuration of a high-speed inductive encoder and a low-speed magnetic encoder, allows the external rotor joint module to be made very small while still ensuring the detection accuracy of the dual encoders.

[0030] By comparing the theoretical mechanical angle value and the absolute mechanical angle value at the low speed end in real time, the system determines whether the encoder is abnormal. When any encoder is abnormal, the system can quickly diagnose and switch to fault-tolerant mode to meet the safety requirements of human-machine collaboration scenarios.

[0031] The low-speed magnetic encoder module can quickly identify the absolute mechanical angle value of the low-speed end of the output shaft at the moment of power-on, which helps the MCU to quickly determine the current revolution range of the high-speed end, shorten the start-up calibration time, and improve the user experience.

[0032] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Attached Figure Description

[0033] Figure 1 An exploded view of the dual encoder external rotor joint module according to an embodiment of the present invention is shown;

[0034] Figure 2 A partially exploded cross-sectional view of the dual encoder external rotor joint module according to an embodiment of the present invention is shown.

[0035] Figure 3 An exploded view of the integrated drive and braiding board, inductor rotor board, inductor coil board, and excitation magnetic ring according to an embodiment of the present invention is shown from a certain perspective.

[0036] Figure 4 An exploded view of the integrated drive and winding board, inductor rotor board, inductor coil board, and excitation magnetic ring of an embodiment of the present invention is shown from another perspective. Detailed Implementation

[0037] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0038] In the description of embodiments of the present invention, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0039] This invention proposes a dual-encoder external rotor joint module, such as... Figures 1 to 4 As shown, the dual encoder external rotor joint module includes a high-speed inductive encoder module and a low-speed magnetic encoder module.

[0040] The high-speed inductive encoder module includes an inductive rotor board 110 and an inductive coil board 120.

[0041] The inductor rotor plate 110 is connected to the rotor 200.

[0042] The external rotor joint module of this embodiment includes a reducer 500, which includes an input shaft and an output shaft. The rotor 200 includes a cylindrical portion and an end plate portion. The end plate portion is connected to the input shaft of the reducer 500, and the inductive rotor plate 110 is also connected to the end plate portion of the rotor 200.

[0043] The inductor coil plate 120 is connected to the drive and braiding integrated plate 300, and the inductor coil plate 120 is located on the side of the drive and braiding integrated plate 300 facing the inductor rotor plate 110. The inductor coil plate 120 and the inductor rotor plate 110 cooperate to obtain the absolute mechanical angle value at the high speed end.

[0044] The external rotor joint module of this embodiment includes a cylindrical integrated drive-braid plate support shell 600. The first axial end of the integrated drive-braid plate support shell 600 is connected to the integrated drive-braid plate 300. Specifically, the integrated drive-braid plate 300 and the integrated drive-braid plate support shell 600 can be connected by screws. An inductor coil plate 120 is connected to the integrated drive-braid plate 300, and the central axis of the inductor coil plate 120 is on the same straight line as the central axis of the inductor rotor plate 110. The diameter of the inductor coil plate 120 is the same as the diameter of the inductor rotor plate 110.

[0045] In this embodiment, the inductor rotor plate 110 has a metal code track arranged along the circumferential direction on the side facing the inductor coil plate 120. Specifically, the code track may include 14 first sensing areas evenly distributed along the first circumferential direction and 3 second sensing areas evenly distributed along the second circumferential direction.

[0046] The inductor coil plate 120 is decorated with excitation coils and receiving coils. In this embodiment, there are two receiving coils with a 90° phase difference. The excitation coil generates a high-frequency alternating magnetic field of 1MHz or higher (e.g., 2.5MHz) within its coil range. When the rotor 200 drives the inductor rotor plate 110 to rotate, the code track of the inductor rotor plate 110 causes a change in the magnetic field (i.e., generates an induced magnetic field that resists the change in the high-frequency alternating magnetic field), and consequently, the magnetic field received by the receiving coils on the inductor coil plate 120 changes. Assuming that when the rotor 200 (i.e., the input shaft of the reducer 500, i.e., the high-speed end) rotates to a certain mechanical angle, the magnetic field received by the first receiving coil is S1 = A × sin(θ) × sin(ωt); the magnetic field received by the second receiving coil (with a 90° phase difference between the two receiving coils) is S2 = A × cos(θ) × sin(ωt).

[0047] The integrated drive and encoder board 300 also includes a microcontroller unit 310, which is connected to two receiving coils. The microcontroller unit 310 can obtain the specific value of sin(β) through the first receiving coil and the specific value of cos(β) through the second receiving coil. Then, the absolute mechanical angle value at the high-speed end can be directly calculated using the formula β=arctan(sin(β) / cos(β)).

[0048] In this embodiment, the high-speed inductive encoder module operates on the principle of eddy currents—the excitation coil generates a high-frequency alternating electromagnetic field, and the code track of the inductive rotor plate 110 generates eddy currents to modulate the receiving coil signal in the reverse direction. Since the rotor 200 (i.e., the motor) is connected to the rotor plate 110, and the magnets inside the motor rotate at the same speed as the rotor plate, the constant external magnetic field cannot generate an alternating induced electromotive force for the high-speed inductive encoder compared to constant magnetic field interference. Therefore, the constant magnetic field has no effect on the inductive encoder. The cumulative mechanical angle value at the high-speed end can be obtained through the absolute mechanical angle value at the high-speed end. Assuming it has rotated two revolutions and the absolute mechanical angle value at the high-speed end for the current revolution is 30°, then the cumulative mechanical angle value at the high-speed end is 750° (i.e., 360° × 2 + 30°). The electrical angle can be obtained by accumulating the mechanical angle value at the high-speed end and the number of pole pairs of the joint motor. Assuming the number of pole pairs of the joint motor P = 3 (i.e., there are 3 pairs of N / S magnetic poles inside the motor), and the accumulated mechanical angle value at the high-speed end is 750°, then the electrical angle is 2250° (i.e., 750° × 3). Since the absolute mechanical angle value at the high-speed end obtained by the high-speed end inductive encoder module in this embodiment is very accurate, the obtained electrical angle is also very accurate. This, in turn, makes the current loop control based on the FOC algorithm (i.e., field-oriented control algorithm) (current loop control requires the use of electrical angle) very accurate, ultimately reducing the heating of the motor and drive board, reducing torque ripple, and suppressing current noise.

[0049] The low-speed magnetic encoder module includes: an excitation magnetic ring 410 and a magnetic sensitive element 420.

[0050] The excitation magnetic ring 410 is connected to the output terminal of the reducer 500. The excitation magnetic ring 410 generates a low-frequency alternating magnetic field of a few hertz (e.g., 2 Hz) as the reducer rotates.

[0051] In this embodiment, the excitation magnetic ring 410 is a multi-stage excitation magnetic ring. The inner circumferential diameter of the excitation magnetic ring 410 is larger than the diameter of the inductor rotor plate 110. The central axis of the excitation magnetic ring 410 and the central axis of the inductor rotor plate 110 are on the same straight line.

[0052] The magnetic sensing element 420 is connected to the integrated drive and braiding plate 300, and is disposed on the side of the integrated drive and braiding plate 300 facing the inductor rotor plate 110. The magnetic sensing element 420 cooperates with the excitation magnetic ring 410 to obtain the absolute mechanical angle value at the low speed end. In this embodiment, the magnetic sensing element 420 is a Hall sensor. The magnetic sensing element 420 is used to sense low-frequency alternating magnetic fields.

[0053] In this embodiment, four magnetic sensing elements 420 are provided, and the four magnetic sensing elements are arranged in a pairwise differential manner. The four magnetic sensing elements are evenly distributed around the outer periphery of the inductor coil plate 120, and the four magnetic sensing elements are exactly aligned with the excitation magnetic ring 410. Assuming that the magnetic sensing elements arranged in sequence along the circumference are magnetic sensing elements 1, 2, 3, and 4, magnetic sensing elements 1 and 2 are 90° apart, magnetic sensing elements 2 and 3 are 90° apart, magnetic sensing elements 3 and 4 are 90° apart, and magnetic sensing elements 4 and 1 are 90° apart. Among them, magnetic sensing elements 1 and 3 form the first sensor pair, and magnetic sensing elements 2 and 4 form the second sensor pair.

[0054] The microcontroller unit 310 of the integrated driver board 300 is connected to four magnetic sensing elements and can acquire the voltage values ​​of the four magnetic sensing elements. A sine wave signal can be obtained by subtracting the voltage value of magnetic sensing element 3 from the voltage value of magnetic sensing element 1 using the first sensor pair. Let's assume it is... A cosine wave signal can be obtained by subtracting the voltage value of magnetic element 4 from the voltage value of magnetic element 2 using the second sensor. Let's assume it is... Finally, through the formula The absolute mechanical angle value at the low speed end can be calculated directly.

[0055] In this embodiment, the external rotor joint module also includes a motor support housing 700, which is connected to the second axial end of the drive-knitting integrated plate support housing 600. The motor support housing 700 is also fixedly connected to the stator, and the housing of the reducer 500 is also fixedly connected to the motor support housing 700. The drive-knitting integrated plate 300 also includes a motor drive circuit 320 and a communication interface 330, which is connected to a host computer. The motor drive circuit 320 controls the stator to drive the rotor 200 to rotate. When the rotor 200 rotates, it drives the inductor rotor plate 110 to rotate. The inductor rotor plate 110, in conjunction with the inductor coil plate 120, can obtain the absolute mechanical angle value at the high-speed end. The rotation of the rotor 200 also drives the input end of the reducer 500 to rotate, thereby causing the output end of the reducer 500 to rotate. When the output end of the reducer 500 rotates, it drives the excitation magnetic ring 410 to rotate. The excitation magnetic ring 410, in conjunction with the magnetic sensitive element 420, can obtain the absolute mechanical angle value at the low-speed end.

[0056] The low-speed magnetic encoder module in this embodiment is located away from the strong magnetic field source of the motor, allowing the magnetic encoder to operate normally at this location. Magnetic encoders are low-cost, simple to integrate, and can directly output accurate absolute mechanical angle values ​​at low speeds, providing a feedback reference with no accumulated error for position loop control.

[0057] Furthermore, in this embodiment, the rotor 200 includes 24 permanent magnets, which are arranged in a circumferential pattern with alternating N and S poles in a 12-pole configuration; the stator adopts a 14-turn fractional-slot concentrated winding structure. This configuration allows for greater torque output within the same physical dimensions, making it particularly suitable for low-speed, high-torque applications such as exoskeletons. However, high pole-pole number motors require higher control precision, and insufficient control precision can lead to significant issues such as overheating and current noise. Therefore, an encoder is needed to provide precise electrical angles. The high-speed inductive encoder module in this embodiment can obtain precise high-speed absolute mechanical angle values, thereby enabling the acquisition of precise electrical angles. Combined with the arrangement of 24 permanent magnets in a circumferential pattern with alternating N and S poles in a 12-pole configuration, this configuration can generate greater torque output without causing overheating or current noise issues.

[0058] Furthermore, in this embodiment, the stator includes a stator coil, which includes an excitation coil and a plurality of induction coils. The excitation coil comprises an outer coil and an inner coil arranged concentrically, and the plurality of induction coils are disposed between the outer coil and the inner coil of the excitation coil, with a predetermined interval maintained between each excitation coil. The plurality of induction coils can identify higher-order harmonic components, fit a more accurate harmonic curve, and improve the static compensation capability for harmonics.

[0059] This invention provides a method for using a dual-encoder external rotor joint module. Employing the dual-encoder external rotor joint module described in the above embodiments, the method includes:

[0060] The absolute mechanical angle value at the high speed end is obtained based on the inductive encoder module at the high speed end. The cumulative mechanical angle value at the high speed end is obtained based on the absolute mechanical angle value at the high speed end and the cumulative number of rotations at the high speed end. The theoretical mechanical angle value at the low speed end is obtained based on the cumulative mechanical angle value at the high speed end and the reduction ratio.

[0061] This embodiment assumes that the absolute mechanical angle value of the high-speed end obtained by the high-speed end inductive encoder module is 90°, and the cumulative number of rotations of the high-speed end is 3. Then the cumulative mechanical angle value of the high-speed end is 1170° (i.e., 360°×3+90°). Assuming the reduction ratio is 10:1, then the theoretical mechanical angle value of the low-speed end is 117° (i.e., 1170°÷10).

[0062] The absolute mechanical angle value at the low speed end is obtained based on the low-speed end magnetic encoder module, and the angle deviation value is obtained based on the absolute mechanical angle value at the low speed end and the theoretical mechanical angle value at the low speed end.

[0063] In this embodiment, it is assumed that the absolute mechanical angle value at the low speed end is 116° obtained by the low speed end magnetic encoder module, then the angle deviation value is 1° (i.e., 116°-117° and then taking the absolute value).

[0064] Determine if the angle deviation value is greater than the angle deviation threshold. If the angle deviation value is greater than the angle deviation threshold, determine that the encoder signal is abnormal.

[0065] In this embodiment, the angle deviation threshold is assumed to be 5°. Since the angle deviation value (1°) is less than the angle deviation threshold (5°), the encoder signal is not determined to be abnormal.

[0066] The high-speed end rotates faster, while the low-speed end rotates slower. Therefore, the microcontroller unit 310 acquires the absolute mechanical angle value of the high-speed end more frequently (e.g., once every 1 ms) and the absolute mechanical angle value of the low-speed end less frequently (e.g., once every 10 ms). The angle deviation value is calculated once every 1 ms, and the same absolute mechanical angle value of the low-speed end is used in all 10 calculations.

[0067] The method in this embodiment further includes: when the determination result is that the encoder signal at the high speed end is abnormal, obtaining the average angular velocity at the high speed end, obtaining the cumulative mechanical angle reference value at the high speed end based on the absolute mechanical angle value at the low speed end and the reduction ratio, and calculating the estimated value of the cumulative mechanical angle at the high speed end based on the average angular velocity at the high speed end, the cumulative mechanical angle reference value at the high speed end, and the time interval value.

[0068] In this embodiment, it is assumed that the theoretical mechanical angle value of the low-speed end obtained at 113ms is 118°, and the absolute mechanical angle value of the low-speed end obtained at 110ms is 110°. Then, the angle deviation value calculated at 113ms is 8°, which is greater than the angle deviation threshold. Therefore, it is determined that the encoder signal of the high-speed end is abnormal.

[0069] When the encoder at the high-speed end experiences a signal abnormality, the microcontroller unit 310 will automatically acquire the average angular velocity at the high-speed end, assuming that the average angular velocity at the high-speed end is 540° / s.

[0070] Assuming the absolute mechanical angle at the low-speed end is 110° at 110ms and the reduction ratio is 10:1, then the cumulative mechanical angle reference value at the high-speed end at 110ms is 1100°. The time interval between 113ms and 110ms is 3ms. When the average angular velocity at the high-speed end is 540° / s, the estimated cumulative mechanical angle at the high-speed end is 1101.62°. When the encoder signal at the high-speed end is abnormal, the microcontroller unit 310 will use the electrical angle calculated from the estimated cumulative mechanical angle at the high-speed end to control the motor to continue running, preventing the motor from directly crashing or stopping due to an error.

[0071] Subsequently, every 1ms, the microcontroller unit 310 will recalculate an angle deviation value. If the angle deviation value is less than or equal to the angle deviation threshold, it means that there is no abnormality in the high-speed encoder signal, and the microcontroller unit 310 will control the motor operation by calculating the electrical angle obtained from the accumulated mechanical angle value of the high-speed end. If the angle deviation value is greater than the angle deviation threshold, it means that there is an abnormality in the high-speed encoder signal, and the microcontroller unit 310 will control the motor operation by calculating the electrical angle obtained from the estimated value of the accumulated mechanical angle of the high-speed end.

[0072] The method in this embodiment further includes: obtaining the cumulative mechanical angle back-calculation value of the high-speed end based on the absolute mechanical angle value of the low-speed end and the reduction ratio, and determining the cumulative number of rotations of the high-speed end based on the cumulative mechanical angle back-calculation value of the high-speed end.

[0073] For example, when powered on, the microcontroller 310 can directly obtain the absolute mechanical angle value of the high-speed end through the high-speed end inductive encoder module, but it does not know the current cumulative number of rotations of the high-speed end. Therefore, the traditional solution needs to perform a complete zeroing action every time it is powered on.

[0074] In this embodiment, the microcontroller 310 can directly obtain the absolute mechanical angle value at the low speed end through the low-speed end magnetic encoder module, assuming it is 60°. Then, the cumulative mechanical angle back-calculation value at the high speed end can be calculated through the reduction ratio. Assuming the reduction ratio is 10:1, the cumulative mechanical angle back-calculation value at the high speed end is 600°. Since 600° = 360° × 1 + 240°, the cumulative rotation number at the high speed end can be directly determined to be 1 through the cumulative mechanical angle back-calculation value at the high speed end. In this embodiment, by setting up the low-speed end magnetic encoder module, the microcontroller 310 can quickly determine the current rotation range of the high speed end (i.e., the cumulative rotation number at the high speed end) without having to perform a complete zero-finding action, thus shortening the startup calibration time.

[0075] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A dual-encoder external rotor joint module, characterized in that, include: The high-speed inductive encoder module includes: An inductor rotor plate (110) is connected to the rotor (200); An inductor coil plate (120) is connected to a drive-braiding integrated plate (300), and the inductor coil plate (120) is disposed on the side of the drive-braiding integrated plate (300) facing the inductor rotor plate (110). The inductor coil plate (120) and the inductor rotor plate (110) cooperate to obtain the absolute mechanical angle value at the high speed end. The low-speed magnetic encoder module includes: The excitation magnetic ring (410) is connected to the output end of the reducer (500); A magnetic sensitive element (420) is connected to the drive-braiding integrated plate (300), and the magnetic sensitive element (420) is disposed on the side of the drive-braiding integrated plate (300) facing the inductor rotor plate (110). The magnetic sensitive element (420) cooperates with the excitation magnetic ring (410) to obtain the absolute mechanical angle value at the low speed end.

2. The external rotor joint module according to claim 1, characterized in that, The inductor rotor plate (110) has a code track arranged in a circumferential direction on the side facing the inductor coil plate (120); the inductor coil plate (120) is provided with a transmitting coil and a receiving coil.

3. The external rotor joint module according to claim 1, characterized in that, The excitation magnetic ring (410) is a multi-stage magnetic ring; there are four magnetic sensitive elements (420), and the four magnetic sensitive elements are arranged in a pairwise differential manner.

4. The external rotor joint module according to claim 1, characterized in that, The integrated drive and programming board (300) is also equipped with a micro control unit (310), a motor drive circuit (320) and a communication interface (330).

5. The external rotor joint module according to claim 1, characterized in that, Also includes: The drive-knitting integrated plate support shell (600) has its first axial end connected to the drive-knitting integrated plate (300); The motor support housing (700) is connected to the second axial end of the drive-bracing integrated plate support housing (600), and the motor support housing (700) is connected to the stator.

6. The external rotor joint module according to claim 1, characterized in that, The rotor (200) includes 24 permanent magnets, which are arranged in a circumferential direction with alternating N and N poles in the form of 12 pairs of poles; the stator adopts a 14-turn fractional-slot concentrated winding structure.

7. The external rotor joint module according to claim 6, characterized in that, The stator includes a stator coil, which includes an excitation coil and a plurality of induction coils. The excitation coil includes an outer coil portion and an inner coil portion arranged concentrically. The plurality of induction coils are disposed between the outer coil portion and the inner coil portion of the excitation coil, and the excitation coils maintain a predetermined interval.

8. A method of using a dual encoder external rotor joint module, employing the dual encoder external rotor joint module as described in any one of claims 1-7, characterized in that, The method includes: The absolute mechanical angle value at the high speed end is obtained based on the high speed end inductive encoder module. The cumulative mechanical angle value at the high speed end is obtained based on the absolute mechanical angle value at the high speed end and the cumulative number of rotations at the high speed end. The theoretical mechanical angle value at the low speed end is obtained based on the cumulative mechanical angle value at the high speed end and the reduction ratio. The absolute mechanical angle value at the low speed end is obtained based on the low speed end magnetic encoder module, and the angle deviation value is obtained based on the absolute mechanical angle value at the low speed end and the theoretical mechanical angle value at the low speed end. Determine whether the angle deviation value is greater than the angle deviation threshold. If the angle deviation value is greater than the angle deviation threshold, determine that the encoder signal is abnormal.

9. The method according to claim 8, characterized in that, Also includes: The cumulative mechanical angle back-calculation value at the high speed end is obtained based on the absolute mechanical angle value at the low speed end and the reduction ratio, and the cumulative number of rotations at the high speed end is determined based on the cumulative mechanical angle back-calculation value at the high speed end.

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