A dual encoder structure for a joint module and a joint module

Abstract

The application discloses a double-encoder structure for a joint module and the joint module, wherein the double-encoder structure comprises a shell, a transmission gear rotatably arranged on the shell, a reducer encoder gear meshing with the transmission gear, a reducer encoder magnetic bead fixed on the reducer encoder gear, an axis of the reducer encoder magnetic bead coinciding with an axis of the reducer encoder gear, a motor encoder gear meshing with the transmission gear, a motor encoder magnetic bead fixed on the motor encoder gear, and an axis of the motor encoder magnetic bead coinciding with an axis of the motor encoder gear, and a circuit board having a reducer encoder chip and a motor encoder chip, the reducer encoder chip aligning with the reducer encoder magnetic bead, and the motor encoder chip aligning with the motor encoder magnetic bead. The double-encoder structure is arranged on the same side, and the reducer encoder chip and the motor encoder chip are integrated on the circuit board, so that the axial size can be effectively reduced, and the torque density can be improved.

Description

Technical Field

[0001] This utility model relates to the field of robot joint technology, specifically to a dual encoder structure for a joint module and a joint module. Background Technology

[0002] In the design and manufacturing of robot joint modules, force-position hybrid control is a core requirement for achieving high-precision motion. To improve control accuracy, traditional solutions typically install independent encoders at the motor end and the reducer output end. The encoder at the motor end is mainly used to monitor the position and speed of the motor's rotating shaft (rotor), while the encoder at the reducer output end is used to detect the actual position and torque of the reducer's output shaft. Although this dual-encoder configuration can provide relatively accurate position feedback and error correction capabilities, this design results in a larger axial dimension. Utility Model Content

[0003] To address the aforementioned problems and overcome the shortcomings, this invention proposes a dual encoder structure for a joint module and a joint module.

[0004] The technical solution adopted by this utility model is as follows:

[0005] A dual encoder structure for a joint module includes:

[0006] case;

[0007] A transmission gear is rotatably mounted on the housing, and the transmission gear is used to connect to the rotating shaft of the motor;

[0008] The reducer encoder gear is rotatably mounted on the housing, and the reducer encoder gear meshes with the transmission gear;

[0009] A reducer encoder bead is fixed on the reducer encoder gear, and the axis of the reducer encoder bead coincides with the axis of the reducer encoder gear.

[0010] A motor encoder gear is rotatably mounted on the housing, and the motor encoder gear meshes with the transmission gear;

[0011] A motor encoder bead is fixed on the motor encoder gear, and the axis of the motor encoder bead coincides with the axis of the motor encoder gear.

[0012] The circuit board has a reducer encoder chip and a motor encoder chip, wherein the reducer encoder chip is aligned with the reducer encoder bead and the motor encoder chip is aligned with the motor encoder bead.

[0013] This application features a dual encoder layout on the same side, with both a reducer encoder chip and a motor encoder chip integrated on the circuit board. This effectively reduces axial dimensions and increases torque density. By mounting magnetic beads on the gears, the high-precision alignment requirements of traditional shaft-end encoders are avoided, reducing assembly difficulty. Since the two magnetic beads are mounted on different gears, their spatial installation positions can be far apart, fundamentally avoiding the magnetic field coupling and signal interference problems that easily occur between magnetic encoders when installed side-by-side or close together in traditional designs. This layout significantly enhances signal independence and signal-to-noise ratio.

[0014] In this application, the reducer encoder gear, reducer encoder bead, and reducer encoder chip work together to monitor the output shaft speed and position of the reducer. Similarly, the motor encoder gear, motor encoder bead, and motor encoder chip work together to monitor the rotational shaft speed and position of the motor. In this application, the reducer encoder gear does not contact the reducer's output shaft; instead, it represents the reducer encoder's output shaft information through simple calculations. Through the design of the transmission gear and the reducer encoder gear, it is possible to achieve n revolutions for every one revolution of the reducer's output shaft, where n is an integer.

[0015] In practical applications, the gear module is designed according to the load accuracy requirements (e.g., module 0.5, gear ratio 1:1) to ensure zero backlash in motion transmission.

[0016] In practical applications, it is preferable that each magnetic bead is strictly aligned with the center of the corresponding chip, with a deviation of less than 0.1mm, in order to reduce signal drift.

[0017] In practical applications, the two chips can be AS5047P magnetic encoder chips.

[0018] In one embodiment of this utility model, the line connecting the center of the transmission gear and the center of the reducer encoder gear is x, the length of x is L1, the line connecting the center of the transmission gear and the center of the motor encoder gear is y, the length of y is L2, and the included angle formed by x and y is a, where 90°≤a≤180°.

[0019] In practical applications, L1 and L2 can be the same or different. 90°≤a≤180° ensures that the reducer encoder gear and the motor encoder gear are located as far apart as possible on opposite sides of the transmission gears, thus increasing the distance between the motor encoder beads and the reducer encoder beads and preventing mutual interference. In practical applications, a is preferably 120°.

[0020] Other existing technologies, in order to improve control accuracy, reduce size, optimize integration and increase torque density, place two magnetic rings or beads in the same area. However, the close proximity of the two magnetic rings or beads can cause interference, making it impossible to obtain accurate position information. Therefore, it is necessary to add a shielding cover or shielding box to ensure the accuracy of data reading, which increases the difficulty of manufacturing and assembly.

[0021] In one embodiment of the present invention, the radius of the reducer encoder bead is R1, the radius of the motor encoder bead is R2, and the distance between the center of the motor encoder gear and the center of the reducer encoder gear is L3, where L3≥2.5(R1+R2), L1≥3R1, and L2≥3R2.

[0022] For example, when R1 = R2 = 3mm, L3 needs to be ≥15mm, and L1 and L2 need to be ≥9mm. This setting can effectively suppress mutual interference between the magnetic fields of the two encoders. This constraint is based on the magnetic field attenuation model (the magnetic field strength is inversely proportional to the cube of the distance), which can ensure that the cross-interference is less than 0.5%, improving the measurement reliability and stability of the system in complex electromagnetic environments. It is particularly suitable for applications with high requirements for anti-interference performance of position detection, such as high-precision servo control systems and robot joint drives.

[0023] In one embodiment of this utility model, the number of teeth on the motor encoder gear is different from the number of teeth on the reducer encoder gear.

[0024] The number of teeth N1 of the transmission gear, the number of teeth N2 of the reducer encoder gear, and the number of teeth N3 of the motor encoder gear must satisfy N2≠N3 in order to ensure the absolute position of the motor, i.e., there is a specific transmission speed ratio difference.

[0025] Based on this differentiated gear ratio structure, the two magnetic encoders can acquire magnetic field signals with phase and speed differences. By processing these two signals and performing calculations according to the preset transmission ratio relationship, the system can accurately calculate the absolute mechanical position and real-time speed information of the motor's rotating shaft and the reducer's output shaft, thereby achieving high-precision absolute position detection.

[0026] In one embodiment of this utility model, the motor encoder gear is made of metal or non-metal material; the reducer encoder gear is made of metal or non-metal material; and the transmission gear is made of metal or non-metal material.

[0027] When the motor encoder gear is made of metal, a non-magnetic sheath is provided between the motor encoder gear and the motor encoder magnetic bead.

[0028] When the reducer encoder gear is made of metal, a non-magnetic sheath is provided between the reducer encoder gear and the reducer encoder magnetic bead.

[0029] When the material is metal (such as steel), eddy current interference can be blocked by setting a non-magnetic sheath. In practical applications, the non-magnetic sheath can be stainless steel or a ceramic ring, etc.

[0030] When the material is non-metallic, PEEK is preferred.

[0031] In one embodiment of the present invention, the motor encoder magnetic bead is fixed to the motor encoder gear by adhesive bonding or press fitting; the reducer encoder magnetic bead is fixed to the reducer encoder gear by adhesive bonding or press fitting.

[0032] In one embodiment of this utility model, the distance between the motor encoder bead and the motor encoder chip is 0.5mm to 1.0mm.

[0033] In practical applications, the preferred distance is 0.8mm.

[0034] In one embodiment of the present invention, the housing has a mounting groove, and the transmission gear, motor encoder gear, reducer encoder gear and circuit board are located in the mounting groove.

[0035] This application also discloses a joint module, including the dual encoder structure for the joint module described above.

[0036] The beneficial effects of this utility model are as follows: The dual encoders on the same side of the circuit board, which integrates the reducer encoder chip and the motor encoder chip, can effectively reduce the axial dimension and improve the torque density. By mounting the magnetic beads on the gears, the high-precision alignment requirements of traditional shaft-end encoders are avoided, reducing assembly difficulty. Since the two magnetic beads are mounted on different gears, their spatial installation positions can be far apart, fundamentally avoiding the magnetic field coupling and signal interference problems that easily occur between magnetic encoders when installed side-by-side or close together in traditional methods. This layout significantly enhances signal independence and signal-to-noise ratio. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a dual encoder structure used in a joint module;

[0038] Figure 2 This is an exploded view of the dual encoder structure used in the joint module;

[0039] Figure 3 This is a top view of the dual encoder structure used for the joint module after the circuit board has been removed.

[0040] The labels for the attached figures are as follows:

[0041] 1. Housing; 2. Mounting slot; 3. Transmission gear; 4. Reducer encoder gear; 5. Reducer encoder magnetic bead; 6. Motor encoder gear; 7. Motor encoder magnetic bead; 8. Circuit board; 81. Reducer encoder chip; 82. Motor encoder chip. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0043] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for 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 application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" 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 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 application based on the specific circumstances.

[0045] The present invention will now be described in detail with reference to the accompanying drawings.

[0046] like Figure 1 , 2 As shown in Figure 3, a dual encoder structure for a joint module includes:

[0047] Casing 1;

[0048] The transmission gear 3 is rotatably mounted on the housing 1 and is used to connect with the rotating shaft of the motor.

[0049] The reducer encoder gear 4 is rotatably mounted on the housing 1, and the reducer encoder gear 4 meshes with the transmission gear 3;

[0050] The reducer encoder bead 5 is fixed on the reducer encoder gear 4, and the axis of the reducer encoder bead 5 coincides with the axis of the reducer encoder gear 4.

[0051] The motor encoder gear 6 is rotatably mounted on the housing 1, and the motor encoder gear 6 meshes with the transmission gear 3;

[0052] The motor encoder bead 7 is fixed on the motor encoder gear 6, and the axis of the motor encoder bead 7 coincides with the axis of the motor encoder gear 6.

[0053] Circuit board 8 has a reducer encoder chip 81 and a motor encoder chip 82. The reducer encoder chip 81 is aligned with the reducer encoder bead 5, and the motor encoder chip 82 is aligned with the motor encoder bead 7.

[0054] The dual encoder layout of this application, with the reducer encoder chip 81 and motor encoder chip 82 integrated on the circuit board 8, effectively reduces axial dimensions and increases torque density. By mounting magnetic beads on the gears, the high-precision alignment requirements of traditional shaft-end encoders are avoided, reducing assembly difficulty. Since the two magnetic beads are mounted on different gears, their spatial installation positions can be far apart, fundamentally avoiding the magnetic field coupling and signal interference problems that easily occur between magnetic encoders when installed side-by-side or close together in traditional designs. This layout significantly enhances signal independence and signal-to-noise ratio.

[0055] In this application, the reducer encoder gear 4, reducer encoder bead 5, and reducer encoder chip 81 cooperate to monitor the output shaft speed and position of the reducer. The motor encoder gear 6, motor encoder bead 7, and motor encoder chip 82 cooperate to monitor the rotational speed and position of the motor shaft. In this application, the reducer encoder gear 4 does not contact the reducer's output shaft; instead, it represents the reducer encoder's output shaft information through simple calculations. Through the design of the transmission gear 3 and the reducer encoder gear 4, it is possible to achieve n revolutions for the reducer's output shaft to rotate one revolution, where n is an integer.

[0056] In practical applications, the gear module is designed according to the load accuracy requirements (e.g., module 0.5, gear ratio 1:1) to ensure zero backlash in motion transmission.

[0057] In practical applications, it is preferable that each magnetic bead is strictly aligned with the center of the corresponding chip, with a deviation of less than 0.1mm, in order to reduce signal drift.

[0058] In practical applications, the two chips can be AS5047P magnetic encoder chips.

[0059] like Figure 3As shown, in this embodiment, the line connecting the center of the transmission gear 3 and the center of the reducer encoder gear 4 is x, and the length of x is L1. The line connecting the center of the transmission gear 3 and the center of the motor encoder gear 6 is y, and the length of y is L2. The included angle formed by x and y is a, and 90°≤a≤180°.

[0060] In practical applications, L1 and L2 can be the same or different. 90°≤a≤180° ensures that the reducer encoder gear 4 and the motor encoder gear 6 are located as far apart as possible on both sides of the transmission gear 3, thus increasing the distance between the motor encoder bead 7 and the reducer encoder bead 5 and preventing mutual interference. In practical applications, a is preferably 120°.

[0061] Other existing technologies, in order to improve control accuracy, reduce size, optimize integration and increase torque density, place two magnetic rings or beads in the same area. However, the close proximity of the two magnetic rings or beads can cause interference, making it impossible to obtain accurate position information. Therefore, it is necessary to add a shielding cover or shielding box to ensure the accuracy of data reading, which increases the difficulty of manufacturing and assembly.

[0062] like Figure 3 As shown, in this embodiment, the radius of the reducer encoder bead 5 is R1, the radius of the motor encoder bead 7 is R2, and the distance between the center of the motor encoder gear 6 and the center of the reducer encoder gear 4 is L3, where L3≥2.5(R1+R2), L1≥3R1, and L2≥3R2.

[0063] For example, when R1 = R2 = 3mm, L3 needs to be ≥15mm, and L1 and L2 need to be ≥9mm. This setting can effectively suppress mutual interference between the magnetic fields of the two encoders. This constraint is based on the magnetic field attenuation model (the magnetic field strength is inversely proportional to the cube of the distance), which can ensure that the cross-interference is less than 0.5%, improving the measurement reliability and stability of the system in complex electromagnetic environments. It is particularly suitable for applications with high requirements for anti-interference performance of position detection, such as high-precision servo control systems and robot joint drives.

[0064] In this embodiment, the number of teeth on the motor encoder gear 6 is different from the number of teeth on the reducer encoder gear 4.

[0065] The number of teeth N1 of transmission gear 3, the number of teeth N2 of reducer encoder gear 4, and the number of teeth N3 of motor encoder gear 6 must satisfy N2≠N3 in order to ensure the absolute position of the motor, i.e., there is a specific transmission speed ratio difference.

[0066] Based on this differentiated gear ratio structure, the two magnetic encoders can acquire magnetic field signals with phase and speed differences. By processing these two signals and performing calculations according to the preset transmission ratio relationship, the system can accurately calculate the absolute mechanical position and real-time speed information of the motor's rotating shaft and the reducer's output shaft, thereby achieving high-precision absolute position detection.

[0067] In this embodiment, the motor encoder gear 6 is made of metal or non-metal; the reducer encoder gear 4 is made of metal or non-metal; and the transmission gear 3 is made of metal or non-metal.

[0068] When the motor encoder gear 6 is made of metal, a non-magnetic sheath is provided between the motor encoder gear 6 and the motor encoder magnetic bead 7.

[0069] When the reducer encoder gear 4 is made of metal, a non-magnetic sheath is provided between the reducer encoder gear 4 and the reducer encoder magnetic bead 5.

[0070] When the material is metal (such as steel), eddy current interference can be blocked by setting a non-magnetic sheath. In practical applications, the non-magnetic sheath can be stainless steel or a ceramic ring, etc.

[0071] When the material is non-metallic, PEEK is preferred.

[0072] In practical applications, the motor encoder magnetic bead 7 is fixed to the motor encoder gear 6 by adhesive bonding or press-fitting; the reducer encoder magnetic bead 5 is fixed to the reducer encoder gear 4 by adhesive bonding or press-fitting.

[0073] In this embodiment, the distance between the motor encoder bead 7 and the motor encoder chip 82 is 0.5mm to 1.0mm, preferably 0.8mm.

[0074] like Figure 1 and 2 As shown, in this embodiment, the housing 1 has a mounting groove 2, and the transmission gear 3, the motor encoder gear 6, the reducer encoder gear 4 and the circuit board 8 are located in the mounting groove 2.

[0075] This embodiment also discloses a joint module, including the dual encoder structure of this embodiment, taking the elbow joint module of a collaborative robot as an example:

[0076] Reduction ratio: 36:1.

[0077] The parameters of the two magnetic beads are: R1 = R2 = 3mm, the material is neodymium iron boron, and the magnetization direction is radial.

[0078] Layout parameters: L1 = L2 = 10mm, L3 = 15mm, α = 120°.

[0079] The reducer encoder gear 4 and the motor encoder gear 6 are made of PEEK, while the transmission gear 3 is made of stainless steel.

[0080] The key steps in the actual assembly process are:

[0081] 1. Gear installation:

[0082] Press the motor encoder gear 6 and the reducer encoder gear 4 into the designated positions in the housing 1 to ensure uniform meshing clearance with the transmission gear 3 (meshing back clearance <0.05mm).

[0083] 2. Magnetic bead fixing:

[0084] The motor encoder magnetic bead 7 is fixed to the center of the motor encoder gear 6 by adhesive or press-fitting, and the reducer encoder magnetic bead 5 is fixed to the center of the reducer encoder gear 4 by adhesive or press-fitting. After curing, check the radial runout of the magnetic bead (must be <0.02mm).

[0085] 3. PCB debugging:

[0086] The circuit board 8 (PCB board) with the reducer encoder chip 81 and the motor encoder chip 82 soldered on it is fixed to the housing 1. The height is adjusted so that the distance between the corresponding chip end face and the corresponding magnetic bead is 0.8mm and the parallelism deviation is <0.1°.

[0087] 4. Calibration and Testing:

[0088] After powering on, perform encoder zero-point calibration (take the average after multiple rotations).

[0089] The curve f(φ,n) of stiffness coefficient K is calibrated using an external torque sensor.

[0090] The signal stability was verified under vibration testing (no error drift at an amplitude of 1.5g).

[0091] The above description is only a preferred embodiment of the present utility model and does not limit the scope of patent protection of the present utility model. Any equivalent structural transformations made based on the content of the present utility model specification and drawings, whether directly or indirectly applied to other related technical fields, are similarly included within the scope of protection of the present utility model.

Claims

1. A dual encoder structure for a joint module, characterized in that, include: case; A transmission gear is rotatably mounted on the housing, and the transmission gear is used to connect to the rotating shaft of the motor; The reducer encoder gear is rotatably mounted on the housing, and the reducer encoder gear meshes with the transmission gear; A reducer encoder bead is fixed on the reducer encoder gear, and the axis of the reducer encoder bead coincides with the axis of the reducer encoder gear. A motor encoder gear is rotatably mounted on the housing, and the motor encoder gear meshes with the transmission gear. A motor encoder bead is fixed on the motor encoder gear, and the axis of the motor encoder bead coincides with the axis of the motor encoder gear. The circuit board has a reducer encoder chip and a motor encoder chip, wherein the reducer encoder chip is aligned with the reducer encoder bead and the motor encoder chip is aligned with the motor encoder bead.

2. The dual encoder structure for a joint module as described in claim 1, characterized in that, The line connecting the center of the transmission gear and the center of the reducer encoder gear is x, and the length of x is L1. The line connecting the center of the transmission gear and the center of the motor encoder gear is y, and the length of y is L2. The included angle between x and y is a, and 90°≤a≤180°.

3. The dual encoder structure for a joint module as described in claim 2, characterized in that, The radius of the encoder bead of the reducer is R1, the radius of the encoder bead of the motor is R2, and the distance between the center of the motor encoder gear and the center of the reducer encoder gear is L3, where L3≥2.5(R1+R2), L1≥3R1, and L2≥3R2.

4. The dual encoder structure for a joint module as described in claim 1, characterized in that, The number of teeth on the motor encoder gear is different from the number of teeth on the reducer encoder gear.

5. The dual encoder structure for a joint module as described in claim 1, characterized in that, When the output shaft of the reducer rotates 1 revolution, the encoder gear of the reducer rotates n revolutions, where n is an integer.

6. The dual encoder structure for a joint module as described in claim 1, characterized in that, The motor encoder gear is made of metallic or non-metallic material; the reducer encoder gear is made of metallic or non-metallic material; the transmission gear is made of metallic or non-metallic material. When the motor encoder gear is made of metal, a non-magnetic sheath is provided between the motor encoder gear and the motor encoder magnetic bead. When the reducer encoder gear is made of metal, a non-magnetic sheath is provided between the reducer encoder gear and the reducer encoder magnetic bead.

7. The dual encoder structure for a joint module as described in claim 1, characterized in that, The motor encoder magnetic bead is fixed to the motor encoder gear by adhesive bonding or press fitting; the reducer encoder magnetic bead is fixed to the reducer encoder gear by adhesive bonding or press fitting.

8. The dual encoder structure for a joint module as described in claim 1, characterized in that, The spacing between the motor encoder bead and the motor encoder chip is 0.5mm to 1.0mm.

9. The dual encoder structure for a joint module as described in claim 1, characterized in that, The housing has a mounting slot, and the transmission gear, motor encoder gear, reducer encoder gear and circuit board are located in the mounting slot.

10. A joint module, characterized in that, Includes the dual encoder structure for joint modules as described in any one of claims 1 to 9.

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