Driving system based on double-rotor magnetic coupling and exoskeleton robot

Abstract

The invention discloses a driving system based on double-rotor magnetic coupling and an exoskeleton robot, the driving system comprises an inner rotor and an outer rotor, the outer rotor is sleeved outside the inner rotor, and the outer rotor and the inner rotor are not in contact; wherein the inner rotor is connected with a bearing seat of an exoskeleton joint shell, and the outer rotor is rigidly connected with an exoskeleton joint driving part; the inner rotor drives the outer rotor to rotate, and then the exoskeleton joint driving part is driven to move.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of exoskeleton robots, and in particular to a driving system based on double-rotor magnetic coupling and an exoskeleton robot. BACKGROUND

[0002] At present, with the problem of population aging and shortage of human resources becoming increasingly serious, exoskeleton robots can play an important role in rehabilitation and medical assistance and walking assistance. Exoskeleton robots not only can assist the elderly and patients who have difficulty in moving to complete daily activities and improve their quality of life, but also can reduce the labor intensity of physical workers and improve work efficiency.

[0003] However, the current exoskeleton robots are heavy, which is not conducive to daily wear, so lightweight design is needed. The lightweight design of the exoskeleton robot needs to balance the "power output" and "portability", but the traditional exoskeleton adopts a driving system of single-rotor motor + reducer, which has two problems: first, the mechanical transmission structure of the reducer increases the weight of the exoskeleton (more than 30% of the overall weight), resulting in heavy wear burden; second, the single motor power regulation response is slow, which is difficult to match the variable torque motion demand of human joints (such as knee joints and hip joints), and is prone to power lag or redundancy.

[0004] The existing lightweight scheme mainly realizes weight reduction by using high-strength lightweight materials, but does not break through the driving core, and cannot solve the contradiction between "weight reduction" and "power adaptation" at the same time. Therefore, developing a lightweight exoskeleton robot based on a new type of motor drive has become the key to improving its wear comfort and motion coordination. SUMMARY

[0005] In view of the problem that the lightweight design of the exoskeleton robot in the prior art is difficult, the present application provides a driving system based on double-rotor magnetic coupling and an exoskeleton robot.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0007] A driving system based on double-rotor magnetic coupling, characterized in that it comprises an inner rotor and an outer rotor, and the outer rotor is sleeved outside the inner rotor without contact between them; wherein the inner rotor is connected with the bearing seat of the exoskeleton joint shell, and the outer rotor is rigidly connected with the exoskeleton joint driving member; the inner rotor drives the outer rotor to rotate, thereby driving the exoskeleton joint driving member to move.

[0008] Preferably, the inner rotor comprises a first shaft 11, a core 12 and a first bearing 13; the core 12 and the first bearing 13 are sleeved on the middle part of the first shaft 11, and the first shaft 11 is connected through the first bearing 13 and the core 12, that is, the first shaft 11 drives the core 12 to rotate through the first bearing 13.

[0009] Preferably, the iron core 12 is a cylindrical structure, and the iron core lamination thickness is 0.35 mm.

[0010] Preferably, the first bearing 13 is two, respectively located at both ends of the iron core 12; the first bearing 13 adopts a deep groove ball bearing.

[0011] Preferably, the circumferential outer surface of the iron core 12 is uniformly provided with N groove positions of the same size, and the groove positions are provided with permanent magnets 14.

[0012] Preferably, the outer side of the permanent magnet 14 comprises a carbon fiber protective layer 15.

[0013] Preferably, the outer rotor comprises a winding 21, a support 22 and a fixing frame 23; the winding 21 is fixed to the inner side of the support 22, and the support 22 is rigidly connected with the exoskeleton joint driving member through the fixing frame 23.

[0014] Preferably, the winding 21 is a hollow circular structure, and the material adopts silver-plated copper enameled wire.

[0015] Preferably, the support 22 is uniformly provided with m first screw holes along the circumference; the fixing frame 23 is uniformly provided with m second screw holes along the circumference.

[0016] The first screw holes of the support 22 and the second screw holes of the fixing frame 23 are rigidly connected with the exoskeleton joint driving member through screws; when the winding 21 rotates, the support 23 and the fixing frame 23 are driven to rotate, and then the exoskeleton joint driving member is driven to move.

[0017] The application also provides an exoskeleton robot adopting a driving system based on double-rotor magnetic coupling.

[0018] In summary, compared with the prior art, the application has at least the following beneficial effects:

[0019] 1) Extremely lightweight: the double-rotor magnetic coupling replaces the reducer, and the lightweight material is combined to reduce the overall weight of the exoskeleton, thereby greatly reducing the wearing burden;

[0020] 2) Accurate power matching: the double-rotor torque is dynamically distributed, the response speed is improved, the human joint variable torque motion can be matched in real time, and power redundancy or lag is avoided;

[0021] 3) High reliability: the inner rotor and the outer rotor have no mechanical contact transmission, the friction loss is reduced, the service life of the motor is prolonged, and the maintenance frequency and cost of the exoskeleton are reduced. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1Fig. 1 is a schematic view of an inner rotor in a driving system based on double-rotor magnetic coupling according to an exemplary embodiment of the present application.

[0023] Figure 2 Fig. 2 is a schematic view of an outer rotor in a driving system based on double-rotor magnetic coupling according to an exemplary embodiment of the present application.

[0024] Figure 3 Fig. 3 is a schematic view of torque distribution principle of the inner rotor and the outer rotor according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0025] The present application will be further described below in conjunction with embodiments and specific implementation manners. However, it should not be understood as the scope of the above-mentioned subject matter of the present application being limited to the following embodiments only, and any technology realized based on the content of the present application falls within the scope of the present application.

[0026] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0027] The present application provides a driving system based on double-rotor magnetic coupling, comprising an inner rotor and an outer rotor, the outer rotor being sleeved outside the inner rotor and the two being in contact; wherein the inner rotor is connected with a bearing seat of an exoskeleton joint shell, and the outer rotor is rigidly connected with an exoskeleton joint driving member (tibial side); the inner rotor drives the outer rotor to rotate, thereby driving the exoskeleton joint driving member to move.

[0028] As shown in Fig. 1, the inner rotor comprises a first rotating shaft 11, a core 12 and a first bearing 13, the core 12 and the first bearing 13 being sleeved in the middle part of the first rotating shaft 11, and the first rotating shaft 11 being connected through the first bearing 13 and the core 12, i.e. when the first rotating shaft 11 rotates, the core 12 is driven to rotate through the first bearing 13. Figure 1

[0029] In this embodiment, the first rotating shaft 11 of the inner rotor is connected with the bearing seat of the exoskeleton joint shell, ensuring the coaxiality and stability when the inner rotor operates at high speed; the core 12 is in a cylindrical structure, and the core lamination thickness is 0.35 mm; the first bearing 13 is two, respectively located at both ends of the core 12, and can be a deep groove ball bearing with model number 6204.

[0030] ​In this embodiment, the circumferential outer surface of the iron core 12 is uniformly provided with N groove positions of the same size, and a permanent magnet 14 (a neodymium iron boron permanent magnet, model N38SH) is arranged in each groove position.

[0031] In this embodiment, in order to prevent the permanent magnet 14 from falling off during high-speed operation, a carbon fiber protective layer 15 with a thickness of 0.2 mm is further arranged outside the permanent magnet.

[0032] As shown in FIGS. 1, 2 and 3, the outer rotor includes a winding 21, a support 22 and a fixing frame 23; the winding 21 is fixed to the inner side of the support 22, and the support 22 is rigidly connected with the exoskeleton joint driving member (tibial side) through the fixing frame 23. Figure 1 Figure 2 As shown in FIGS. 1, 2 and 3, the outer rotor includes a winding 21, a support 22 and a fixing frame 23; the winding 21 is fixed to the inner side of the support 22, and the support 22 is rigidly connected with the exoskeleton joint driving member (tibial side) through the fixing frame 23.

[0033] In this embodiment, the winding 21 is a hollow circular structure (without an iron core), and a silver-plated copper enameled wire (wire diameter 0.2 mm) can be used as the material; the winding 21 can be made by weaving technology, and has a thickness of 2 mm. The air gap between the inner side of the winding 21 and the inner rotor is 0.3-0.5 mm.

[0034] In this embodiment, the support 22 is uniformly provided with m first screw holes along the circumference, and the fixing frame 23 is uniformly provided with m second screw holes along the circumference. Screws can be used to rigidly connect the exoskeleton joint driving member (tibial side) through the first screw holes of the support 22 and the second screw holes of the fixing frame 23. In this way, when the winding 21 rotates, the support 22 and the fixing frame 23 can be driven to rotate, and then the exoskeleton joint driving member moves.

[0035] In this embodiment, the air gap magnetic field of the double-rotor may have magnetic density attenuation, so an ultra-thin samarium-cobalt permanent magnet ring is embedded between the inner and outer rotors. By minimizing the magnetic resistance (the air gap thickness is controlled to be 0.3-0.5 mm), the magnetic coupling loss is reduced, and the torque transmission efficiency is maintained above 92%. The ultra-thin samarium-cobalt permanent magnet ring can compensate for the magnetic density attenuation of the air gap magnetic field of the inner and outer rotors, enhance the air gap magnetic field strength, reduce the magnetic coupling loss, and ensure the stability of the magnetic field through its high coercive force characteristics, so that the torque transmission efficiency is maintained above 92%.

[0036] In this embodiment, the ultra-thin samarium-cobalt permanent magnet ring is in a ring structure (thickness 0.2 mm), and can be pasted to the inner side of the winding 21 by high-temperature-resistant glue, and forms a cooperative magnetic circuit with the permanent magnet 14 of the inner rotor.

[0037] In this embodiment, the principle of driving the outer rotor by the inner rotor is as follows:

[0038] ​The inner rotor and the outer rotor form a magnetic coupling effect through an air gap magnetic field. The permanent magnet 14 of the inner rotor generates a constant main magnetic field. When the inner rotor rotates, the main magnetic field cuts the winding 21 of the outer rotor, and an induced current is generated in the winding 21. The induced current is subjected to an electromagnetic force in the main magnetic field, and an electromagnetic torque for driving the outer rotor to rotate is formed. The rotation direction of the outer rotor is consistent with that of the inner rotor, so that torque transmission without mechanical contact is realized, and the outer rotor and the connected exoskeleton joint are driven to move.

[0039] In the embodiment, through the magnetic coupling effect, the outer rotor and the inner rotor form torque difference compensation. The winding current is corrected in real time by using the Jiles-Atherton hysteresis model, and the high-speed low-torque of the inner rotor is converted into the low-speed high-torque required by the exoskeleton.

[0040] In the embodiment, the method for correcting the winding current is as follows:

[0041] A1: Based on the Jiles-Atherton hysteresis model, a relationship equation between the winding current and the hysteresis loss is established:

[0042]

[0043] In formula (1), H is the magnetic field strength, B is the magnetic induction strength, μ0 is the vacuum permeability, and M is the magnetization strength.

[0044] A2: The actual output torque T 内实 of the inner rotor is collected by a sensor, and the theoretical required torque T 外需 of the outer rotor is collected by a sensor, and the torque difference is calculated:

[0045] ΔT=T 外需 -T 内实 ×η (2)

[0046] In formula (2), ΔT is the torque difference; T 外需 is the theoretical required torque of the outer rotor; T 内实 is the actual output torque of the inner rotor; and η is the basic efficiency of magnetic coupling, which is initially taken as 0.92.

[0047] A3: According to ΔT, the required winding magnetization strength increment ΔM is back calculated, the corresponding winding current adjustment amount ΔI is solved by substituting the Jiles-Atherton hysteresis model, and the winding current of the outer rotor is corrected in real time.

[0048] In the embodiment, the calculation method for converting the high-speed low-torque of the inner rotor into the low-speed high-torque required by the exoskeleton is as follows:

[0049] It is assumed that the rotation speed of the inner rotor is n1, the output torque is T1, the rotation speed of the outer rotor is n2, and the output torque is T2. According to the power conservation relationship of the magnetic coupling transmission: n1×T1=n2×T2×η 磁 , η磁 For the magnetic coupling efficiency, take 0.92-0.95;

[0050] The known internal rotor high-speed low-torque characteristics (such as n1 = 3000 r / min, T1 = 5 N·m) are combined with the exoskeleton joint requirements (such as n2 = 300 r / min), and the formula is used to calculate the output torque of the external rotor: Finally, the high-speed low-torque is converted into low-speed high-torque (example calculation T2 ≈ 46 N·m).

[0051] In this embodiment, the torque of the internal rotor and the external rotor is superimposed by the double-rotor torque superposition method, so as to improve the torque response speed of the driving system and adapt to the instantaneous force demand of the human joint (such as the knee joint torque fluctuation when going up and down stairs).

[0052] Torque superposition is not simply a numerical addition, but a dynamic cooperative output based on the motion working condition. When the internal rotor outputs torque T 内 , the external rotor compensates the output torque T 外 through magnetic coupling, and the two form a resultant torque T 总 in the same direction of rotation T 内 × k ' 1+ T 外 × k ' 2 (k ' 1, k ' 2 are dynamic weight coefficients, which are adjusted in real time according to the working condition), which ensures that the total torque accurately matches the instantaneous demand of the human joint. For example, when going up and down stairs, the weight coefficient k ' 2 of the external rotor increases, and the low-speed high-torque output is strengthened.

[0053] In this embodiment, as shown in Figure 3 , a "human motion intention-double rotor torque distribution" mapping model is established, the human joint torque (F) is collected through the force sensor at the exoskeleton joint, the motion speed (v) is combined, and the internal and external rotor torques are dynamically distributed to ensure that the double-rotor torque superposition accurately matches the human motion demand:

[0054] T 内 = k1 × F × v, T 外 = k2 × F / v (3)

[0055] In formula (3), T 内 is the output torque of the internal rotor; T 外 is the output torque of the external rotor; k1 is the torque coefficient of the internal rotor (0.6-0.8 is taken in high-speed working condition); k2 is the torque coefficient of the external rotor (0.7-0.9 is taken in low-speed high-load working condition); F is the human joint torque; and v is the motion speed.

[0056] The establishment process of the "human motion intention-dual rotor torque distribution" mapping model is as follows:

[0057] Data acquisition: through the force sensor and angular velocity sensor of the exoskeleton joint, the joint torque F, motion speed v and motion posture data of the human body under different motion conditions (walking, going up and down stairs, climbing, etc.) are collected to construct a sample data set;

[0058] Feature extraction: the collected sample data set is subjected to feature extraction by wavelet transform, and the feature parameters (such as torque change rate, speed peak value, etc.) strongly related to torque demand are screened out;

[0059] Model training: based on the BP neural network algorithm, the feature parameters are taken as input, and the optimal torque distribution ratio is taken as output to train the model, and the network weight is optimized by the gradient descent method;

[0060] Verification and correction: in the actual wearing test, the torque distribution result output by the model is compared with the actual demand of the human body, the model parameters are continuously adjusted to ensure that the prediction accuracy of the model is greater than or equal to 95%.

[0061] The application also provides an exoskeleton robot adopting the driving system based on dual rotor magnetic coupling.

[0062] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for realizing the application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the application.

Claims

1. A driving system based on dual-rotor magnetic coupling, characterized in that, It comprises an inner rotor and an outer rotor, the outer rotor is sleeved outside the inner rotor and the two are not in contact; wherein the inner rotor is connected with the bearing seat of the exoskeleton joint shell, the outer rotor is rigidly connected with the exoskeleton joint driving part; the inner rotor drives the outer rotor to rotate, and then drives the exoskeleton joint driving part to move.

2. A drive system based on magnetic coupling of double rotors as claimed in claim 1 characterized in that, The inner rotor comprises a first rotating shaft (11), an iron core (12) and a first bearing (13); the iron core (12) and the first bearing (13) are sleeved in the middle part of the first rotating shaft (11), and the first rotating shaft (11) is connected through the first bearing (13) and the iron core (12), that is, the first rotating shaft (11) drives the iron core (12) to rotate through the first bearing (13).

3. A dual-rotor magnetic coupling-based drive system as claimed in claim 2, characterized in that, The iron core (12) is a cylindrical structure, and the thickness of the iron core lamination is 0.35mm.

4. A dual-rotor magnetic coupling-based drive system as claimed in claim 2, wherein, The first bearing (13) is two, respectively located at both ends of the iron core (12); the first bearing (13) adopts a deep groove ball bearing.

5. A dual-rotor magnetic coupling-based drive system as claimed in claim 2, wherein, The circumferential outer surface of the iron core (12) is uniformly provided with N same size slot positions, and a permanent magnet (14) is arranged in the slot position.

6. A dual-rotor magnetic coupling-based drive system as claimed in claim 5, characterized in that, The outer side of the permanent magnet (14) comprises a carbon fiber protective layer (15).

7. A dual-rotor magnetic coupling-based drive system as claimed in claim 1, wherein, The outer rotor comprises a winding (21), a bracket (22) and a fixing frame (23); the winding (21) is fixed on the inner side of the bracket (22), and the bracket (22) is rigidly connected with the exoskeleton joint driving part through the fixing frame (23).

8. A dual-rotor magnetic coupling-based drive system as claimed in claim 7, characterized in that, The winding (21) is a hollow circular structure, and the material adopts silver-plated copper enameled wire.

9. A dual-rotor magnetic coupling-based drive system as claimed in claim 7, wherein, The The bracket (22) is uniformly provided with m first screw holes along the circumference; the fixing frame (23) is uniformly provided with m second screw holes along the circumference; The screw is rigidly connected with the exoskeleton joint driving part through the first screw hole of the bracket (22) and the second screw hole of the fixing frame (23); when the winding (21) rotates, the bracket (23) and the fixing frame (23) are driven to rotate, and then the exoskeleton joint driving part is driven to move.

10. An exoskeleton robot characterized by comprising: The exoskeleton robot adopts the driving system based on double rotor magnetic coupling according to any one of claims 1-9.

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