Exoskeleton finger joint off-axis motor module

Abstract

The invention provides an exoskeleton finger joint off-axis motor module which comprises a servo motor, a straight gear speed reducer, an arc rack, a first-stage arc track, a second-stage arc track and a motor module shell. A final-stage gear of the straight gear speed reducer is an arc rack, first-stage arc tracks are symmetrically arranged on the two sides of the arc rack and are arranged to be first ball grooves containing bearing steel balls, and second-stage arc tracks are arranged on the outer sides of the first-stage arc tracks and are arranged to be second ball grooves containing bearing steel balls. Second ball grooves are formed in the two sides of the second-stage arc track respectively, a plurality of bearing steel balls are contained in the second ball grooves, the second-stage arc track is matched with the shell ball grooves in the inner wall of the motor module shell through the steel balls on the outermost layer to move, and the rotation angle of the arc rack is 45 degrees. The arc rack achieves the purpose that the motor module drives the finger joints to rotate by 90 degrees through the synergistic effect of the first-stage arc track and the second-stage arc track. According to the invention, the motion angle of finger rehabilitation is covered, and the adaptability of providing auxiliary strength is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of exoskeleton equipment, and in particular relates to an off-axis motor module for an exoskeleton finger joint. Background Art

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

[0003] First, conventional motor modules are large in size and difficult to adapt to the delicate structure of the hand, which limits the portability and comfort of the exoskeleton device; secondly, the motor cogging torque is large, resulting in large fluctuations in the output torque when the motor is running, and it is impossible to achieve more precise joint torque control, affecting the stability of the device and the user experience; traditional reduction motors use higher reduction ratios or reducers with self-locking characteristics to achieve greater torque output, resulting in large critical back-drive torque of the exoskeleton or even inability to back-drive, and therefore cannot meet the lower impedance output requirements of the exoskeleton in active rehabilitation scenarios; in addition, the shaft of an ordinary motor module cannot be concentric with the shaft of the human hand joint, and natural and flexible movement of the hand cannot be achieved; and the existing modules are difficult to meet the rehabilitation needs of 90-degree rotation of human finger joints, which greatly limits the application effect of exoskeleton equipment in the field of hand rehabilitation.

[0004] Therefore, there is an urgent need in this field for a motor module with small motor cogging torque, which can realize natural and flexible movement of the hand and can meet 90-degree rotation of the finger joints. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the object of the present invention is to provide an off-axis motor module for an exoskeleton finger joint.

[0006] The present invention provides an off-axis motor module for an exoskeleton finger joint, comprising:

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

[0008] The stator of the servo motor is designed with an oblique slot, 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 reduction device is coaxially connected to the output shaft of the servo motor, the final gear of the spur gear reduction device is a circular arc rack, and the arc center axis of the circular arc rack is concentrically arranged with the rotation axis of the finger joint;

[0010] The arc rack is symmetrically provided with a first-stage arc track on both sides, the first-stage arc track is configured as a first ball groove, and the first ball groove is filled with a plurality of bearing steel balls. The second-stage arc track is provided on the outside of the first-stage arc track, and the second-stage arc track is provided with a second ball groove on both sides thereof and filled with a plurality of bearing steel balls. The second-stage arc track moves in coordination with the outermost layer of steel balls and the outer shell ball groove on the inner wall of the motor module housing;

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

[0012] According to an off-axis motor module for an exoskeleton finger joint provided by the present invention, the angle between the stator 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 an off-axis motor module for an exoskeleton finger joint provided by the present invention, the spur gear reduction device includes a multi-stage gear transmission, a first-stage gear and multiple transmission gears are provided in the spur gear reduction device, and the first-stage gear is provided with a circular opening for coaxial connection with the output shaft of the servo motor.

[0014] According to an off-axis motor module for an exoskeleton finger joint provided by the present invention, 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 is meshed with the second-stage gear, the second-stage gear is meshed with the third-stage gear, the third-stage gear is meshed with the fourth-stage gear, and the fourth-stage gear is meshed with the circular arc rack.

[0015] According to an off-axis motor module for an exoskeleton finger joint provided by the present invention, 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.

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

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

[0018] According to an off-axis motor module for an exoskeleton finger joint provided by the present invention, the second-stage circular 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 an off-axis motor module for an exoskeleton finger joint provided by the present invention, a positioning pin is provided at the connection between the first half part and the second half part.

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

[0021] The present invention provides an off-axis motor module for exoskeleton finger joints. The collaborative design of the two-stage circular arc track cleverly solves the limitation that a single-stage circular arc gear can only rotate 45 degrees. Through the cascade amplification effect of the first-stage and second-stage circular arc tracks, a full range of 90-degree rotation is achieved, fully meeting the physiological movement requirements 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] The present invention uses an ultra-thin, high-power-density outer rotor brushless servo motor to provide powerful driving force in a very small space. Compared with the thickness of traditional motor modules, the servo motor of the present invention significantly improves the wearability and comfort of exoskeleton equipment. Users will not have a noticeable sense of weight or restraint during long-term use, which greatly improves the user experience and lays the foundation for the daily application of exoskeleton equipment.

[0023] Secondly, the stator skew of the present invention, combined with the cogging torque compensation algorithm, reduces the motor cogging torque, the vibration amplitude during motor operation, and the noise level. The smooth operation characteristics not only extend the service life of the equipment, but also provide users with a quieter and more comfortable rehabilitation training environment, avoiding the negative impact of mechanical noise generated by traditional motors on the patient's psychological state. The set reduction ratio ensures sufficient output torque while ensuring excellent back-drive capability, making the reverse resistance of the motor module extremely small in passive mode, allowing 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 smooth hand movements with the assistance of the equipment, which improves 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 axis. The precise alignment eliminates the additional stress and motion interference caused by the misalignment of the axes in the traditional design, making the force applied to the fingers more uniform and reasonable during movement, reducing the stress concentration at the joints, and effectively avoiding the risk of joint injury caused by long-term use. At the same time, the naturalness of the movement trajectory is significantly improved, and the deviation between the user's finger movement and normal physiological movement is reduced.

[0025] The ball grooves reduce the friction coefficient of the entire transmission system, reducing rotational resistance compared to traditional sliding bearings. This low-friction feature not only improves transmission efficiency but also significantly extends the device's lifespan and reduces maintenance costs. Precise angle control and optimized meshing angles between gears in the multi-stage gear transmission reduce power loss during transmission, significantly improving overall transmission efficiency, extending the device's battery life, reducing charging frequency, and providing users with extended continuous training capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals represent the same components. Obviously, the drawings described below are only some of the embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings.

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

[0028] Figure 2 A schematic diagram of the axial side of the motor module housing provided by an embodiment of the present invention;

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

[0030] Figure 4 A schematic diagram of the axial side of the arc rack provided by an embodiment of the present invention;

[0031] Figure 5 This is an axial schematic diagram of the second-stage circular arc track provided by an embodiment of the present invention;

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

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

[0034] Reference numerals:

[0035] 1. Servo motor; 2. Spur gear reduction device; 3. Arc rack; 4. First-stage arc track; 5. Second-stage 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 DESCRIPTION

[0036] In order 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 embodiments described are part of the embodiments of the present invention, rather than all of the 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 of ordinary skill in the art without creative work should fall within the scope of protection of the present invention.

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

[0038] In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with certain aspects of the present 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 an exoskeleton finger joint, comprising: a servo motor (1), a spur gear reduction device (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-mentioned 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 motion assistance, thereby realizing the precise conversion from the rotational motion of the motor to the natural arc motion of the finger joint.

[0043] The off-axis motor module for the exoskeleton finger joints of the present invention adopts an off-axis design concept for the entire module. Unlike traditional direct-axis transmission, the traditional motor output shaft cannot coincide with the physiological rotation axis of the human finger joints. The present invention solves the biomechanical adaptation problem through an off-axis circular arc design, allowing the exoskeleton device to better fit the natural movement trajectory of the human finger.

[0044] like Figure 2FIG. 1 is a schematic diagram of a motor module housing in an off-axis motor module for an exoskeleton finger joint provided by the present invention, wherein Figure 2 A in the middle is a schematic diagram of the axial right side of the motor module housing. Figure 2 B in the middle is a schematic diagram of the axial left side of the motor module housing. The motor module housing is designed as a left-right split structure, and the left and right splits are fixedly connected through fixed spaces.

[0045] The stator of the servo motor (1) is designed with inclined slots, the motor shaft of the servo motor (1) is perpendicular to the bottom surface of the motor module housing (6), and 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 of the entire module. The specific configuration uses an ultra-thin, high-power-density outer rotor brushless servo motor structure. The advantage is that it can provide sufficient driving torque in a limited space while maintaining the compactness of the module. The stator of the motor adopts a skewed slot design to reduce the 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 in the horizontal direction relative to the center line of the motor module, which is the basis for realizing off-axis transmission and creates the necessary geometric conditions for the subsequent arc transmission chain.

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

[0049] The included angle between the stator slots of the servo motor (1) and the axis of the servo motor (1) is 15° to 30°, and the motor driver for controlling the servo motor (1) is equipped with a cogging torque compensation algorithm.

[0050] Furthermore, the stator slot design angle of the motor of the present invention is controlled between 15° and 30°, which can effectively reduce the cogging torque during motor operation. Combined with the cogging torque compensation algorithm in the driver, it can significantly reduce the vibration and noise during motor operation and improve the operating 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 motor poles and slots to offset the torque pulsation caused by the slot torque; then, when the motor is in the no-load state, the driver detects the rotor position and back-electromotive force waveform to establish a mapping relationship between the amplitude and phase of the slot torque; finally, according to 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 reduction device (2) is coaxially connected to the output shaft of the servo motor (1); the final gear of the spur gear reduction device (2) is a circular arc rack (3); and the arc center axis of the circular arc rack (3) is concentrically arranged with the rotation axis of the finger joint.

[0053] Furthermore, the spur gear reduction device in the present invention serves as a link between the motor and the arc transmission mechanism, and undertakes the functions of torque amplification and speed reduction. The arc rack adopts an arc shape, so that the center axis of the arc is concentrically set with the rotation axis of the finger joint. That is, through the off-axis arc design, the center axis of the arc and the rotation axis of the finger joint are virtually coincident, thereby realizing off-axis transmission.

[0054] Wherein, 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 converts high-speed low-torque into low-speed high-torque. Based on the output torque requirements, back-drive capability and response speed, the larger reduction ratio set by the present invention can significantly increase the output torque, meet the power requirements of passive rehabilitation exercises of the hand, and at the same time ensure that the motor has good back-drive capability, so that the exoskeleton device can sensitively follow the active movement 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 provided with a first ball groove, and a plurality of bearing steel balls are installed in the first ball groove. The second-stage arc track (5) is provided on the outside of the first-stage arc track (4), and second ball grooves (51) are provided on both sides of the second-stage arc track (5) and are installed with a plurality of bearing steel balls. The second-stage arc track (5) moves in coordination with the outer shell ball groove on the inner wall of the motor module shell (6) through the outermost layer of steel balls. 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 coordinated action of the first-stage arc track (4) and the second-stage arc track (5).

[0057] Further, such as Figure 4As shown, the first-stage arc track cooperates with the movement of the arc rack and is symmetrically arranged on both sides of the arc rack. The first-stage arc track is essentially a first ball groove system with multiple bearing steel balls inside. The second-stage arc track is arranged on the outside of the first-stage arc track, forming a double-layer arc transmission structure. Second ball grooves are respectively provided on both sides of the second-stage arc track. The second-stage arc track forms a coordinated motion relationship with the outer shell ball groove on the inner wall of the motor module shell through the outermost layer of steel balls, forming the entire transmission chain.

[0058] Furthermore, the above-mentioned two-stage circular arc track system realizes a 90-degree rotation angle of the electrode module of the present invention. Since a single circular arc rack can only provide a 45-degree rotation due to geometric and structural limitations, the collaborative working mechanism of the first-stage circular arc track and the second-stage circular arc track enables 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 is mechanically coupled with the first-stage circular arc track to continue the second 45-degree rotation segment based on the movement of the first-stage track. The two-stage track maintains synchronization through the ball transmission mechanism to ensure the smoothness and accuracy of the entire 90-degree rotation process.

[0060] like Figure 6 As shown, Figure 6 Figure A is a schematic diagram of the motor module output end with a rotation angle of 0 degrees. Figure 6 In the middle, B is the 90-degree rotation angle of the motor module output end. During transmission, the motor drives the arc rack through the reducer device, so that the arc rack meshes along the rack on 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 along the connection relative to the end of the arc rack. After the first-stage arc track, i.e., the first ball groove, reaches the end, the second-stage transmission connection is performed, i.e., the first-stage track pushes the steel balls of the second-stage track through the ball grooves on both sides, transmitting the force to the second-stage arc track. Finally, the outermost steel balls are connected to the ball groove on the inner wall of the motor module housing, causing the motor module housing to rotate a corresponding angle.

[0061] Specifically, when the double arc track is in the initial state, that is, 0 degrees, the first and second stage tracks are aligned with no relative displacement. When the track moves from 0 to 45 degrees, the motor drives the gear to rotate the first stage track 45 degrees. At this time, the second stage track has not moved temporarily due to the limitation of the ball groove of the outer shell, and gradually the balls in the ball groove of the first stage track begin to approach the steel balls of the second stage track. When the track moves from 45 to 90 degrees, the first stage track reaches its limit, and the steel balls push the second stage track to continue rotating 45 degrees. The outer steel balls of the second stage track slide along the ball groove of the outer shell to complete the remaining angle.

[0062] like Figure 3 As shown, the spur gear reduction device 2 includes a multi-stage gear transmission, and a first-stage gear 21 and multiple transmission gears are provided in the spur gear reduction device 2. 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 first-stage gear is a large-diameter ring gear with an inner ring gear structure, and the teeth are distributed on the inner side of the ring. A circular opening is provided in the center for supporting the motor output shaft to pass through. Multiple positioning holes are provided around the circular opening, which cooperate with the protruding positioning columns at the output end of the servo motor to support the synchronous rotation of the servo motor and the first-stage gear, so that the first-stage gear serves as the starting end of the entire transmission chain.

[0064] The transmission gear includes 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 is meshed with the second-stage gear 23, the second-stage gear 23 is meshed with the third-stage gear 24, the third-stage gear 24 is meshed with the fourth-stage gear 25, and the fourth-stage gear 25 is meshed with the arc rack 3.

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

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

[0067] Furthermore, the ball groove of the present invention adopts an arc-shaped cross-section, which can form conformal contact between the cross-section and the spherical steel ball, thereby 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] In addition, the groove depth set by the present invention is 1 / 2 of the steel ball diameter. This is because when the depth of the ball groove is exactly half of the diameter of the bearing steel ball, the contact area between the steel ball and the groove wall reaches the optimal state. From the perspective of contact mechanics, when the steel ball is embedded in the groove to a depth of 1 / 2 diameter, the contact stress distribution is most uniform. If the groove depth is too shallow (less than 1 / 2 diameter), the contact area between the steel ball and the groove wall is reduced, which will lead to contact stress concentration and increase the risk of wear; if the groove depth is too deep (greater than 1 / 2 diameter), the steel ball will be excessively sunken into the groove, limiting its rolling freedom and increasing rolling resistance; secondly, from the perspective of load-bearing capacity, the groove depth of 1 / 2 diameter provides the best radial load-bearing capacity. In the exoskeleton finger joint application of the present invention, the system needs to withstand various complex loads from finger movement including radial force, axial force and moment load. The ball groove of the present 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 both provided with a ball retainer, 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.

[0070] Furthermore, the present invention selects bearing tin bronze as the ball retainer material. Tin bronze has excellent wear resistance, self-lubrication and corrosion resistance, which is crucial for the long-term reliable operation of exoskeleton equipment. In addition, tin bronze has a moderate hardness, which can withstand the extrusion pressure of the ball without causing damage to the precision bearing steel balls. Its self-lubricating properties can still maintain a low friction coefficient 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 retainer in the ball groove is consistent with the tangent direction of the arc track. When the installation angle of the retainer is consistent with the tangent direction of the track, the direction of the restraint force on the ball during movement is completely matched with its movement trajectory, which minimizes unnecessary friction and wear. At the same time, it ensures that the ball retainer 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 on the second-stage circular arc track (5) are provided with a preset spacing 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 on the second-stage circular arc track (5) in the horizontal direction is 120° to 150°.

[0073] Furthermore, a preset spacing is set in the vertical direction between the ball groove on the inner wall of the motor module housing and the second-stage arc track ball groove. In a specific embodiment, it is 15 to 20 mm. The preset spacing enables the two rows of ball systems to bear independent loads. When one row of balls bears a larger load, the other row of balls can provide auxiliary support to achieve effective load distribution. In exoskeleton applications, system paralysis caused by single point failure can be avoided.

[0074] In addition, the set meshing angle of 120° to 150° can achieve higher 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. For the application scenario of the present invention, that is, the motion characteristics of the exoskeleton finger joints, based on the natural motion trajectory of the human finger joints, the design range of 120° to 150° also ensures that the system can cover the main motion range of the finger joints.

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

[0076] like Figure 5 The figure shows a schematic diagram of the second-stage arc track in an off-axis motor module of an exoskeleton finger joint of the present invention. Figure 5 A in the middle is a schematic diagram of the first half. Figure 5 B in the middle is a schematic diagram of the second half.

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

[0078] In addition, the second-stage circular arc track in the present invention is connected by bolts, which also provides a certain adjustment capability. During the assembly process, the relative position between the two halves can be controlled by adjusting the tightening torque of the bolts to ensure that the geometric accuracy of the entire circular arc track meets the design requirements.

[0079] Wherein, a positioning pin (54) is provided at the connection between the first half part (52) and the second half part (53).

[0080] like Figure 5As shown, in Figure 5 The first half of the middle A is provided with a groove, Figure 5 The positioning pin of the second half of B is used for preliminary positioning. Through holes of corresponding number and position are provided on both sides of the positioning pin to support the connection of the two halves by bolts.

[0081] Furthermore, the positioning pins can ensure the precise alignment of the two halves. During the assembly process, the positioning pins first achieve rough positioning, and then achieve precise fixation through the tightening of the connecting bolts, which can improve assembly efficiency and accuracy.

[0082] The present invention provides an off-axis motor module for an exoskeleton finger joint. The module outputs power to a spur gear reduction device through an ultra-thin high-power density outer rotor brushless servo motor. The device adopts a multi-stage gear transmission structure. The power transmission path is the first-stage gear → the first-stage gear → the second-stage gear → the third-stage gear → the fourth-stage gear. Through a reduction ratio of 45:1, the high-speed and low-torque of the motor is converted into a low-speed and high-torque output to meet the power requirements of passive rehabilitation exercises of the hand. Subsequently, the circular arc rack (3) connected to the fourth-stage gear converts the rotational motion into an arc swinging motion. The rotation angle of the fourth-stage gear is 45 degrees. Then, through the synergistic effect of the first-stage circular arc track and the second-stage circular arc track, the circular arc gear is realized. The angle of the movement of the bar is amplified, wherein the first-stage circular arc track is set as the first ball groove equipped with multiple bearing steel balls, which directly follows the arc rack movement to complete the first 45-degree rotation segment, and 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, the second 45-degree rotation segment is continued on the basis of the first-stage track movement. Finally, the second-stage circular arc track cooperates with the outer shell ball groove on the inner wall of the motor module housing through the outermost layer of steel balls. When the double-stage circular arc track system is working, the two 45-degree motion segments are superimposed to form a complete 90-degree rotation, which finally drives the motor module housing to rotate the corresponding angle to achieve precise control of the finger joints.

[0083] The off-axis motor module for the exoskeleton finger joints 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 in traditional direct-axis transmission cannot coincide with the physiological rotation axis of the human finger joints. The off-axis arc design achieves biomechanical adaptation, allowing the exoskeleton device to better fit the natural movement trajectory of the human finger.

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

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

[0086] Finally, it should be noted that the above embodiments are merely illustrative of 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 aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or replacements that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. An off-axis motor module for an exoskeleton finger joint, characterized in that: include: Servo motor, spur gear reduction device, arc rack, first-stage arc track, second-stage arc track, motor module housing; The stator of the servo motor is designed with an oblique slot, 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 reduction device is coaxially connected to the output shaft of the servo motor, the final gear of the spur gear reduction device is a circular arc rack, and the arc center axis of the circular arc rack is concentrically arranged with the rotation axis of the finger joint; The first-stage circular arc track is symmetrically provided on both sides of the circular arc rack, and the first-stage circular arc track is configured as a first ball groove, and the first ball groove is filled with multiple bearing steel balls. The second-stage circular arc track is provided on the outer side of the first-stage circular arc track, and second ball grooves are respectively provided on both sides of the second-stage circular arc track and filled with multiple bearing steel balls. The second-stage circular arc track moves in coordination with the outermost layer of steel balls and the outer shell ball groove on the inner wall of the motor module housing; The rotation angle of the arc rack is 45 degrees. The arc rack realizes the motor module driving the finger joint to rotate 90 degrees through the coordinated action of the first-level arc track and the second-level arc track.

2. The off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that: The included angle between the stator skew slots 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.

3. The exoskeleton finger joint off-axis motor module according to claim 1, characterized in that: The spur gear reduction device includes a multi-stage gear transmission. A first-stage gear and a plurality of transmission gears are provided in the spur gear reduction device. The first-stage gear is provided with a circular opening for coaxial connection with the output shaft of the servo motor.

4. The exoskeleton finger joint off-axis motor module 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 is engaged with the second-stage gear, the second-stage gear is engaged with the third-stage gear, the third-stage gear is engaged with the fourth-stage gear, and the fourth-stage gear is engaged with the circular arc rack.

5. The exoskeleton finger joint off-axis motor module according to claim 1, characterized in that: 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.

6. The off-axis motor module for exoskeleton finger joints according to claim 5, characterized in that: A ball retainer is provided in each of the first ball groove and the second ball groove. The ball retainer is made of bearing tin bronze material. 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. The exoskeleton finger joint off-axis motor module 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 arc track are provided with a preset spacing in the vertical direction, and the meshing angle of 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°.

8. The off-axis motor module for exoskeleton finger joints according to claim 1, characterized in that: The second-stage circular 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.

9. The exoskeleton finger joint off-axis motor module according to claim 8, characterized in that: A positioning pin is provided at the connection between the first half part and the second half part.

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

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