An off-axis motor module for exoskeleton finger joints

Abstract

This invention proposes an off-axis motor module for exoskeleton finger joints, comprising: a servo motor, a spur gear reducer, an arc rack, a first-stage arc track, a second-stage arc track, and a motor module housing. The final gear of the spur gear reducer is an arc rack. The first-stage arc tracks are symmetrically arranged on both sides of the arc rack, each consisting of a first ball groove containing bearing steel balls. The second-stage arc track is located outside the first-stage arc track, with second ball grooves on both sides containing multiple bearing steel balls. The second-stage arc track moves by engaging with the outermost steel balls in the ball grooves on the inner wall of the motor module housing. The arc rack rotates at a 45-degree angle. Through the synergistic effect of the first and second-stage arc tracks, the motor module drives the finger joint to rotate 90 degrees. This invention covers the range of motion required for finger rehabilitation and improves the adaptability of providing assistive force.

Description

Technical Field

[0001] This invention belongs to the field of exoskeleton equipment technology, and in particular relates to an off-axis motor module for exoskeleton finger joints. Background Technology

[0002] With the development of rehabilitation medicine and wearable device technology, exoskeleton devices are being used more and more widely in hand rehabilitation training and enhancing hand motor ability. However, existing exoskeleton finger joint motor modules have many shortcomings.

[0003] First, conventional motor modules are bulky and difficult to adapt to the delicate structure of the hand, limiting the portability and comfort of exoskeleton devices. Second, the large cogging torque of motors leads to significant fluctuations in output torque during operation, making it impossible to achieve more precise joint torque control, affecting device stability and user experience. Traditional geared motors use higher reduction ratios or self-locking reducers to achieve greater torque output, resulting in large or even non-existent critical counter-drive torques on the exoskeleton, thus failing to meet the lower impedance output requirements of exoskeletons in active rehabilitation scenarios. Furthermore, the shaft of ordinary motor modules cannot be concentric with the shaft of human hand joints, preventing natural and flexible hand movements. Moreover, existing modules cannot meet the rehabilitation needs of 90-degree rotation of human finger joints, greatly limiting the application effectiveness of exoskeleton devices in the field of hand rehabilitation.

[0004] Therefore, there is an urgent need in this field for a motor module with low cogging torque, which can enable natural and flexible hand movements and allow finger joints to rotate 90 degrees. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the invention is to provide an off-axis motor module for exoskeleton finger joints.

[0006] This invention provides an off-axis motor module for exoskeleton finger joints, comprising:

[0007] Servo motor, spur gear reducer, circular arc rack, first-stage circular arc track, second-stage circular arc track, motor module housing;

[0008] The stator of the servo motor has a skewed slot design, the motor shaft of the servo motor is perpendicular to the bottom surface of the motor module housing, and the servo motor is offset relative to the center line of the motor module in the horizontal direction.

[0009] The spur gear reducer is coaxially connected to the output shaft of the servo motor. The last stage gear of the spur gear reducer is a circular arc rack, and the central axis of the circular arc rack is concentric with the rotation axis of the finger joint.

[0010] The circular arc rack has a first-stage circular arc track symmetrically arranged on both sides. The first-stage circular arc track is a first ball groove, which contains multiple bearing steel balls. The second-stage circular arc track is located outside the first-stage circular arc track. The second-stage circular arc track has a second ball groove on each side, which contains multiple bearing steel balls. The second-stage circular arc track moves by cooperating with the outermost steel ball in the outer shell ball groove on the inner wall of the motor module housing.

[0011] The rotation angle of the circular arc rack is 45 degrees. The circular arc rack achieves the motor module driving the finger joint to rotate 90 degrees through the coordinated action of the first-level circular arc track and the second-level circular arc track.

[0012] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the angle between the stator skew slot of the servo motor and the axis of the servo motor is 15° to 30°, and the motor driver for controlling the servo motor is configured with a cogging torque compensation algorithm.

[0013] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the spur gear reduction device includes a multi-stage gear transmission, wherein the spur gear reduction device is provided with a primary gear and a plurality of transmission gears, and the primary gear is provided with a circular opening for coaxial connection with the output shaft of the servo motor.

[0014] According to the present invention, an off-axis motor module for exoskeleton finger joints includes a transmission gear comprising a first stage gear, a second stage gear, a third stage gear, and a fourth stage gear. The first stage gear meshes with the second stage gear, the second stage gear meshes with the third stage gear, the third stage gear meshes with the fourth stage gear, and the fourth stage gear meshes with a circular arc rack.

[0015] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the first ball groove and the second ball groove are both ground, the cross-section of the first ball groove and the cross-section of the second ball groove are both arc-shaped, and the groove depth of the first ball groove and the groove depth of the second ball groove are both 1 / 2 of the diameter of the bearing steel ball they support.

[0016] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein a ball retainer is provided in both the first ball groove and the second ball groove. The ball retainer is made of bearing tin bronze material, and the installation angle of the ball retainer in the corresponding ball groove is consistent with the tangent direction of the arc track in the corresponding ball groove.

[0017] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the ball groove on the inner wall of the motor module housing and the ball groove of the second-stage arc track are provided with a preset distance in the vertical direction, and the meshing angle between the ball groove on the inner wall of the motor module housing and the ball groove of the second-stage arc track in the horizontal direction is 120° to 150°.

[0018] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the second-stage arc track includes a first half and a second half, the arc angle of the first half and the second half is 45°, and the first half and the second half are connected and fixed by connecting bolts.

[0019] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein a positioning pin is provided at the connection between the first half and the second half.

[0020] According to the present invention, an off-axis motor module for exoskeleton finger joints is provided, wherein the reduction ratio of the spur gear reduction device is 45.

[0021] This invention provides an off-axis motor module for exoskeleton finger joints. The collaborative design of two-stage circular arc tracks ingeniously solves the limitation of a single-stage circular arc gear that can only rotate 45 degrees. Through the cascading amplification effect of the first and second-stage circular arc tracks, a full range of 90-degree rotation is achieved, fully meeting the physiological movement needs of human finger joints. This design enables the exoskeleton device to support full-range finger rehabilitation training from full extension to full flexion, doubling the coverage of rehabilitation training and providing a more comprehensive rehabilitation solution for patients with different degrees of hand dysfunction.

[0022] This invention achieves powerful driving force in a very small space by using an ultra-thin, high-power-density external rotor brushless servo motor. Compared with the thickness of traditional motor modules, the servo motor of this invention significantly improves the wearability and comfort of exoskeleton devices. Users will not experience obvious weight or restraint during long-term use, greatly improving the user experience and laying the foundation for the daily application of exoskeleton devices.

[0023] Secondly, the stator skew slot and cogging torque compensation algorithm of this invention reduces the motor cogging torque, decreases the vibration amplitude during motor operation, and lowers the noise level. This stable operation not only extends the lifespan of the equipment but also provides users with a quieter and more comfortable rehabilitation training environment, avoiding the negative impact of mechanical noise from traditional motors on the patient's psychological state. The set reduction ratio ensures sufficient output torque while guaranteeing excellent reverse drive capability, resulting in minimal reverse resistance in the motor module in passive mode. This allows the exoskeleton device to accurately sense and follow the user's active movement intentions, providing an ideal mechanical environment for active rehabilitation training. Patients can perform more natural and fluid hand movements with the assistance of the device, ultimately improving the overall rehabilitation effect.

[0024] In addition, the off-axis arc of the present invention achieves perfect alignment between the motor output shaft and the human joint shaft. Precise alignment eliminates the additional stress and motion interference caused by the misalignment of the shafts in traditional designs, making the force on the fingers more uniform and reasonable during movement, reducing stress concentration at the joints, effectively avoiding the risk of joint damage that may be caused by long-term use, and significantly improving the naturalness of the movement trajectory, reducing the deviation between the user's finger movement and normal physiological movement.

[0025] The ball bearing grooves reduce the coefficient of friction in the entire transmission system, decreasing rotational resistance compared to traditional sliding bearings. This low-friction characteristic not only improves transmission efficiency but also significantly extends the equipment's lifespan and reduces maintenance costs. Precise angle control and optimized meshing angles between gears in multi-stage gear transmissions reduce power loss during transmission, significantly improving overall transmission efficiency, extending equipment runtime, reducing charging frequency, and providing users with longer periods of continuous training capability. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. It is obvious that the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings.

[0027] Figure 1 An exploded view of an off-axis motor module structure for an exoskeleton finger joint provided in an embodiment of the present invention;

[0028] Figure 2 This is an axial side view of the motor module housing provided in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the shaft side of a spur gear reduction device provided in an embodiment of the present invention;

[0030] Figure 4 This is an axial view of the circular arc rack provided in an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of the second-stage circular arc track provided in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the assembly of the circular arc rack and the second-stage circular arc track provided in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the servo motor shaft provided in an embodiment of the present invention.

[0034] Figure label:

[0035] 1. Servo motor; 2. Spur gear reducer; 3. Circular arc rack; 4. First-stage circular arc track; 5. Second-stage circular arc track; 6. Motor module housing; 21. First-stage gear; 22. First-stage gear; 23. Second-stage gear; 24. Third-stage gear; 25. Fourth-stage gear; 51. Second ball groove; 52. First half; 53. Second half; 54. Positioning pin. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0037] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with some aspects of the invention as detailed in the appended claims.

[0040] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0041] like Figure 1 As shown, the present invention provides an off-axis motor module for exoskeleton finger joints, comprising: a servo motor (1), a spur gear reducer (2), an arc rack (3), a first-stage arc track (4), a second-stage arc track (5), and a motor module housing (6).

[0042] Furthermore, based on the mechanical coordination and transmission relationship of the above components, the exoskeleton finger joint off-axis motor module provided by the present invention can be used as a precision electromechanical device for hand rehabilitation training and sports assistance, realizing the precise conversion from the rotational motion of the motor to the natural arc motion of the finger joint.

[0043] The exoskeleton finger joint off-axis motor module of the present invention adopts the off-axis design concept. Unlike traditional straight-axis transmission, the output shaft of the traditional motor cannot coincide with the physiological rotation axis of the human finger joint. However, the present invention solves the biomechanical adaptation problem through off-axis arc design, so that the exoskeleton device can better conform to the natural movement trajectory of the human finger.

[0044] like Figure 2The diagram shown is a schematic of the motor module housing in an off-axis motor module for exoskeleton finger joints provided by the present invention. Figure 2 A in the diagram is a schematic diagram of the right side of the motor module housing along its axis. Figure 2 Figure B is a schematic diagram of the left side of the motor module housing along the axis. The motor module housing has a split structure design, and the left and right parts are fixedly connected by fixed slots.

[0045] The stator of the servo motor (1) is designed with a skewed slot. The motor shaft of the servo motor (1) is perpendicular to the bottom surface of the motor module housing (6). The servo motor (1) is offset relative to the center line of the motor module in the horizontal direction.

[0046] Furthermore, the servo motor serves as the power source for the entire module. In the specific configuration, an ultra-thin high-power-density external rotor brushless servo motor structure is used. Its advantage lies in providing sufficient driving torque within a limited space while maintaining the compactness of the module. The stator of the motor adopts a skewed slot design, which aims to reduce cogging torque.

[0047] From the perspective of positional relationship, the motor shaft of the servo motor of the present invention is perpendicular to the bottom surface of the motor module housing, which is conducive to the compact design of the entire module. At the same time, the servo motor is offset relative to the center line of the motor module in the horizontal direction, which is the basis for realizing off-axis transmission and creates the necessary geometric conditions for the subsequent circular arc transmission chain.

[0048] like Figure 7 As shown, Figure 7 This is a schematic diagram of the servo motor of the present invention. Figure 7 A in the diagram is the left side of the axis. Figure 7 In the diagram, B represents the right side of the axis.

[0049] The angle between the stator skew slot of the servo motor (1) and the axis of the servo motor (1) is 15° to 30°, and the motor driver used to control the servo motor (1) is equipped with a cogging torque compensation algorithm.

[0050] Furthermore, the stator skew design angle of the motor of the present invention is controlled between 15° and 30°, which can effectively reduce the cogging torque when the motor is running. Combined with the cogging torque compensation algorithm in the driver, it can significantly reduce the vibration and noise when the motor is running and improve the running stability of the entire system.

[0051] The specific compensation algorithm is as follows: First, a specific harmonic component is injected into the three-phase current of the motor. The harmonic frequency is an integer multiple of the number of pole slots of the motor, which is used to offset the torque pulsation caused by the cogging torque. Then, under the no-load condition of the motor, the rotor position and back electromotive force waveform are detected by the driver to establish a mapping relationship between the amplitude and phase of the cogging torque. Finally, based on the calibration data and the current rotor position, the q-axis current component is dynamically adjusted so that the compensation torque and the cogging torque are opposite in phase and equal in amplitude.

[0052] The spur gear reducer (2) is coaxially connected to the output shaft of the servo motor (1). The last gear of the spur gear reducer (2) is a circular arc rack (3), and the circular arc center axis of the circular arc rack (3) is concentric with the rotation axis of the finger joint.

[0053] Furthermore, the spur gear reduction device in this invention serves as a link between the motor and the arc transmission mechanism, undertaking the functions of torque amplification and speed reduction. The arc rack adopts an arc shape, so that its arc center axis is concentric with the rotation axis of the finger joint. That is, by using the off-axis arc design, the arc center axis is virtually coincident with the rotation axis of the finger joint, thus realizing off-axis transmission.

[0054] The reduction ratio of the spur gear reduction device (2) is 45.

[0055] Furthermore, the reduction ratio of the entire reduction device of the present invention is designed to be 45:1, which transforms high speed and low torque into low speed and high torque. Based on the consideration of output torque requirements, anti-drive capability and response speed, the larger reduction ratio set by the present invention can significantly improve the output torque, meet the force requirements of passive rehabilitation exercises of the hand, and at the same time ensure that the motor has good anti-drive capability, so that the exoskeleton device can sensitively follow the active movements of the hand.

[0056] The arc rack (3) is symmetrically provided with first-stage arc tracks (4) on both sides. The first-stage arc track (4) is set as a first ball groove, and multiple bearing steel balls are installed in the first ball groove. The second-stage arc track (5) is located outside the first-stage arc track (4). The second-stage arc track (5) is provided with second ball grooves (51) on both sides and is filled with multiple bearing steel balls. The second-stage arc track (5) moves by cooperating with the outermost steel ball and the outer shell ball groove on the inner wall of the motor module housing (6). The rotation angle of the arc rack (3) is 45 degrees. The arc rack (3) realizes the motor module driving the finger joint to rotate 90 degrees through the synergistic effect of the first-stage arc track (4) and the second-stage arc track (5).

[0057] Furthermore, such as Figure 4As shown, the first-stage circular arc track, in coordination with the movement of the circular arc rack, is symmetrically arranged on both sides of the circular arc rack. The first-stage circular arc track is essentially a first ball groove system, which contains multiple bearing steel balls. The second-stage circular arc track is located outside the first-stage circular arc track, forming a double-layer circular arc transmission structure. The second-stage circular arc track has second ball grooves on both sides. The second-stage circular arc track forms a coordinated motion relationship with the outermost steel ball and the outer shell ball groove on the inner wall of the motor module housing through the outermost steel ball, thus forming the entire transmission chain.

[0058] Furthermore, the aforementioned dual-stage circular arc track system enables the electrode module of the present invention to rotate 90 degrees. Since a single circular arc rack is limited by geometry and structure to provide only 45 degrees of rotation, the cooperative working mechanism of the first-stage circular arc track and the second-stage circular arc track allows the two 45-degree motion segments to be superimposed to form a complete 90-degree rotation.

[0059] The first-stage circular arc track directly follows the movement of the circular arc rack to complete the first 45-degree rotation segment. The second-stage circular arc track, through mechanical coupling with the first-stage track, continues to complete the second 45-degree rotation segment based on the movement of the first-stage track. The two tracks are kept synchronized through a ball bearing transmission mechanism to ensure the smoothness and accuracy of the entire 90-degree rotation process.

[0060] like Figure 6 As shown, Figure 6 A in the diagram represents the output angle of the motor module at 0 degrees. Figure 6 In the diagram, B represents a 90-degree rotation angle at the output end of the motor module. During transmission, the motor drives the arc rack via a reducer, causing the arc rack to mesh along its tooth surface. The arc rack passes through the steel balls in the first-stage arc track, causing the end of the second-stage arc track to move in the opposite direction relative to the end of the arc rack along the connection point. After the first-stage arc track, i.e., the first ball groove, reaches its end, the second-stage transmission connection is established. That is, the first-stage track pushes the steel balls of the second-stage track through the ball grooves on both sides, transmitting force to the second-stage arc track. Finally, the outermost steel ball connects with the ball groove on the inner wall of the motor module housing, causing the motor module housing to rotate by the corresponding angle.

[0061] Specifically, when the double circular arc track is in its initial state, i.e., 0 degrees, the first and second level tracks are aligned with no relative displacement. As the temperature approaches 45 degrees, the motor drives the gears, causing the first level track to rotate 45 degrees. At this point, the second level track remains stationary due to the limitation imposed by the ball grooves in the outer shell. Gradually, the balls in the ball grooves of the first level track begin to approach the steel balls of the second level track. When the temperature approaches 90 degrees, the first level track reaches its limit and is then pushed by the steel balls to continue rotating the second level track by 45 degrees. The outer steel balls of the second level track slide along the ball grooves in the outer shell, completing the remaining angle.

[0062] like Figure 3 As shown, the spur gear reducer 2 includes a multi-stage gear transmission. The spur gear reducer 2 is provided with a first-stage gear 21 and multiple transmission gears. The first-stage gear 21 is provided with a circular opening for coaxial connection with the output shaft of the servo motor 1.

[0063] Furthermore, the primary gear is a large-diameter ring gear with an internal gear ring structure. The teeth are distributed on the inner side of the ring, and a circular opening is provided in the center to support the motor output shaft to pass through. Multiple positioning holes are provided around the circular opening to cooperate with the protruding positioning pins at the output end of the servo motor to support the servo motor and the primary gear to rotate synchronously, so that the primary gear serves as the starting end of the entire transmission chain.

[0064] The transmission gears include a first-stage gear 22, a second-stage gear 23, a third-stage gear 24, and a fourth-stage gear 25. The first-stage gear 22 meshes with the second-stage gear 23, the second-stage gear 23 meshes with the third-stage gear 24, the third-stage gear 24 meshes with the fourth-stage gear 25, and the fourth-stage gear 25 meshes with the arc rack 3.

[0065] Furthermore, the first-stage gear is located to the lower left of the first-stage gear, forming an internal and external meshing transmission with the gear ring of the first-stage gear, receiving the initial power from the motor. Additionally, the diameter of the first-stage gear is smaller than that of the first-stage gear, achieving the initial reduction and torque increase. The second-stage gear meshes with the first-stage gear, and the third-stage gear meshes with the second-stage gear to receive power, while simultaneously transmitting torque to the fourth-stage gear. As can be seen from the layout in the diagram, the fourth-stage gear, as the final output stage of the transmission chain, directly meshes with the circular arc rack, performing the crucial task of converting rotational motion into circular arc oscillating motion, ensuring smooth power transmission.

[0066] The first ball groove and the second ball groove (51) are both ground. The cross-section of the first ball groove and the cross-section of the second ball groove (51) are both arc-shaped. The groove depth of the first ball groove and the groove depth of the second ball groove (51) are both 1 / 2 of the diameter of the bearing steel ball they support.

[0067] Furthermore, the ball groove of the present invention adopts an arc-shaped cross section, which allows the cross section to form a conformal contact with the spherical steel ball, minimizing contact stress and friction loss, ensuring that the movement trajectory of the ball in the groove is predictable and stable, and avoiding abnormal wear caused by geometric mismatch.

[0068] Furthermore, the groove depth set in this invention is half the diameter of the steel ball. This is because when the depth of the ball groove is exactly half the diameter of the bearing steel ball, the contact area between the steel ball and the groove wall reaches its optimal state. From the perspective of contact mechanics, when the steel ball is embedded in the groove to a depth of half the diameter, the contact stress distribution is the most uniform. If the groove depth is too shallow (less than half the diameter), the contact area between the steel ball and the groove wall decreases, which leads to contact stress concentration and increases the risk of wear. If the groove depth is too deep (greater than half the diameter), the steel ball will sink excessively into the groove, restricting its rolling freedom and increasing rolling resistance. Secondly, from the perspective of load-bearing capacity, a groove depth of half the diameter provides the best radial load-bearing capacity. In the exoskeleton finger joint application of this invention, the system needs to withstand various complex loads from finger movements, including radial force, axial force, and moment load. The ball groove of this invention ensures that the ball can maintain a stable working state under various load conditions.

[0069] The first ball groove and the second ball groove (51) are provided with ball retainers. The ball retainers are made of bearing tin bronze. The installation angle of the ball retainer in the corresponding ball groove is consistent with the tangent direction of the arc track in the corresponding ball groove.

[0070] Furthermore, this invention selects bearing tin bronze as the ball cage material. Tin bronze has excellent wear resistance, self-lubrication, and corrosion resistance, which are crucial for the long-term reliable operation of exoskeleton equipment. Moreover, tin bronze has moderate hardness, which can withstand the extrusion force of the balls without damaging the precision bearing balls. Its self-lubricating properties can maintain a low coefficient of friction even when the lubricant is insufficient or fails, which is of great significance for improving the reliability of the system and extending its service life.

[0071] In addition, the installation angle of the ball cage in the ball groove is consistent with the tangent direction of the arc track. When the installation angle of the cage is consistent with the tangent direction of the track, the direction of the constraint force on the ball during the movement is completely matched with its movement trajectory, which minimizes unnecessary friction and wear, and ensures that the ball cage can maintain a stable working state throughout the entire movement stroke, avoiding vibration, noise or premature failure caused by angular deviation.

[0072] The ball groove on the inner wall of the motor module housing (6) and the ball groove of the second-stage circular arc track (5) are provided with a preset distance in the vertical direction, and the meshing angle between the ball groove on the inner wall of the motor module housing (6) and the ball groove of the second-stage circular arc track (5) in the horizontal direction is 120° to 150°.

[0073] Furthermore, the ball groove on the inner wall of the motor module housing and the ball groove of the second-stage circular arc track are set with a preset distance in the vertical direction, which is 15 to 20 mm in a specific embodiment. The preset distance allows the two rows of ball systems to bear the load independently. When one row of balls bears a large load, the other row of balls can provide auxiliary support to achieve effective load distribution. In exoskeleton applications, this can avoid system paralysis caused by single-point failure.

[0074] In addition, the meshing angle of 120° to 150° can achieve high transmission efficiency. When the meshing angle is less than 120°, the contact pressure between the ball and the groove wall will increase significantly, resulting in increased friction loss. When the meshing angle is greater than 150°, the stability of the transmission will be affected, and there may be a risk of the ball disengaging from the contact. For the application scenario of this invention, namely the motion characteristics of the exoskeleton finger joint, based on the natural motion trajectory of the human finger joint, the design range of 120° to 150° also ensures that the system can cover the main motion range of the finger joint.

[0075] The second-level circular arc track (5) includes a first half (52) and a second half (53), the arc angle of the first half (52) and the second half (53) is 45°, and the first half (52) and the second half (53) are connected and fixed by connecting bolts.

[0076] like Figure 5 The diagram shown is a schematic of the second-stage circular arc track in an off-axis motor module for exoskeleton finger joints according to the present invention. Figure 5 A in the diagram represents the first half. Figure 5 B in the diagram represents the second half.

[0077] Furthermore, the second-level circular arc track in this invention has a first half and a second half each with a circular arc angle of 45°, which corresponds to the physiological range of motion of human finger joints and also corresponds to the rotation stage of the aforementioned double-level circular arc track. Each stage is about 45°, with a total bending range of 90°. This not only improves the accuracy of motion control but also enables the system of this invention to better adapt to the finger size and movement habits of different users.

[0078] Furthermore, the second-stage circular arc track in this invention is connected by bolts, which also provides a certain degree of adjustability. During the assembly process, the relative position between the two halves can be controlled by adjusting the tightening torque of the bolts, ensuring that the geometric accuracy of the entire circular arc track meets the design requirements.

[0079] The first half (52) and the second half (53) are provided with a positioning pin (54).

[0080] like Figure 5As shown, in Figure 5 The first half of part A has a groove, which is consistent with... Figure 5 The second half of B is fitted with a locating pin for initial positioning. Corresponding number and position through holes are provided on both sides of the locating pin to support the connection of the two halves by bolts.

[0081] Furthermore, the locating pins ensure precise alignment of the two halves. During assembly, the locating pins first achieve coarse positioning, and then precise fixing is achieved by tightening the connecting bolts, which can improve assembly efficiency and accuracy.

[0082] This invention provides an off-axis motor module for exoskeleton finger joints. Power is output from an ultra-thin, high-power-density external rotor brushless servo motor to a spur gear reduction device. This device employs a multi-stage gear transmission structure, with the power transmission path being: first-stage gear → first-stage gear → second-stage gear → third-stage gear → fourth-stage gear. A 45:1 reduction ratio converts the motor's high-speed, low-torque output into low-speed, high-torque output, meeting the power requirements of passive hand rehabilitation exercises. Subsequently, the circular arc rack (3) connected to the fourth-stage gear converts rotational motion into circular arc swinging motion. Its rotation angle is 45 degrees. Then, through the synergistic action of the first-stage and second-stage circular arc tracks, the circular arc gear... The movement angle of the rack is magnified. The first-stage circular arc track is set as the first ball groove with multiple bearing steel balls, which directly follows the movement of the circular arc rack to complete the first 45-degree rotation segment. The second-stage circular arc track is set outside the first-stage circular arc track, with second ball grooves on both sides. Through mechanical coupling with the first-stage circular arc track, it continues to complete the second 45-degree rotation segment based on the movement of the first track. Finally, the second-stage circular arc track moves in conjunction with the outermost steel ball and the outer shell ball groove on the inner wall of the motor module housing. When the dual-stage circular arc track system is working, the two 45-degree movement segments are superimposed to form a complete 90-degree rotation, which ultimately drives the motor module housing to rotate by the corresponding angle, realizing precise control of the finger joints.

[0083] The exoskeleton finger joint off-axis motor module of the present invention is mainly used in the fields of hand rehabilitation training and sports assistance. The special off-axis design of the present invention solves the problem that the motor output shaft cannot coincide with the physiological rotation axis of the human finger joint in traditional straight shaft transmission. The off-axis arc design achieves biomechanical adaptation, enabling the exoskeleton device to better conform to the natural movement trajectory of the human finger.

[0084] This invention achieves a precise conversion from the rotational motion of the motor to the natural arc-shaped motion of the finger joints. It not only provides sufficient output torque but also ensures that the motor has good counter-drive capability, enabling the exoskeleton device to sensitively follow the active movements of the hand. The 90-degree rotation range completely covers the main movement range of the finger joints, providing precise and natural rehabilitation training and motor assistance support for patients with hand dysfunction.

[0085] In summary, this invention proposes an off-axis motor module for exoskeleton finger joints through mechanical design and transmission, which solves the problems of exoskeleton finger joint motor modules in terms of size, stability, and biomechanical adaptability, and provides important technical support for the development of hand rehabilitation training and sports assistive devices.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. An off-axis motor module for exoskeleton finger joints, characterized in that, include: Servo motor, spur gear reducer, circular arc rack, first-stage circular arc track, second-stage circular arc track, motor module housing; The stator of the servo motor has a skewed slot design, the motor shaft of the servo motor is perpendicular to the bottom surface of the motor module housing, and the servo motor is offset relative to the center line of the motor module in the horizontal direction. The spur gear reducer is coaxially connected to the output shaft of the servo motor. The last stage gear of the spur gear reducer is a circular arc rack, and the central axis of the circular arc rack is concentric with the rotation axis of the finger joint. The circular arc rack has symmetrical first-stage circular arc tracks on both sides. The first-stage circular arc tracks are configured as first ball grooves, and multiple bearing steel balls are installed in the first ball grooves. The second-stage circular arc tracks are located outside the first-stage circular arc tracks. The second-stage circular arc tracks have second ball grooves on both sides and multiple bearing steel balls are installed in them. The second-stage circular arc tracks move by cooperating with the outermost steel ball in the outer shell ball groove on the inner wall of the motor module housing. The second-level circular arc track includes a first half and a second half, the circular arc angle of the first half and the second half is 45°, and the first half and the second half are connected and fixed by connecting bolts; The rotation angle of the circular arc rack is 45 degrees. The circular arc rack achieves the motor module driving the finger joint to rotate 90 degrees through the coordinated action of the first-level circular arc track and the second-level circular arc track.

2. The exoskeleton finger joint off-axis motor module according to claim 1, characterized in that, The angle between the stator skew slot of the servo motor and the axis of the servo motor is 15° to 30°, and the motor driver used to control the servo motor is equipped with a cogging torque compensation algorithm.

3. The exoskeleton finger joint off-axis motor module according to claim 1, characterized in that, The spur gear reducer includes a multi-stage gear transmission. The spur gear reducer is provided with a primary gear and multiple transmission gears. The primary gear has a circular opening for coaxial connection with the output shaft of the servo motor.

4. An off-axis motor module for exoskeleton finger joints according to claim 3, characterized in that, The transmission gear includes a first-stage gear, a second-stage gear, a third-stage gear, and a fourth-stage gear. The first-stage gear meshes with the second-stage gear, the second-stage gear meshes with the third-stage gear, the third-stage gear meshes with the fourth-stage gear, and the fourth-stage gear meshes with a circular arc rack.

5. An off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that, Both the first ball groove and the second ball groove have been ground. The cross-section of the first ball groove and the cross-section of the second ball groove are both arc-shaped. The groove depth of the first ball groove and the groove depth of the second ball groove are both 1 / 2 of the diameter of the bearing steel ball they support.

6. An off-axis motor module for exoskeleton finger joints according to claim 5, characterized in that, Both the first ball groove and the second ball groove are provided with ball retainers. The ball retainers are made of bearing tin bronze. The installation angle of the ball retainer in the corresponding ball groove is consistent with the tangent direction of the arc track in the corresponding ball groove.

7. An off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that, The ball groove on the inner wall of the motor module housing and the ball groove of the second-stage circular arc track are provided with a preset distance in the vertical direction, and the meshing angle between the ball groove on the inner wall of the motor module housing and the ball groove of the second-stage circular arc track in the horizontal direction is 120° to 150°.

8. An off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that, A locating pin is provided at the connection between the first half and the second half.

9. An off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that, The reduction ratio of the spur gear reducer is 45.

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