A biomimetic knee exoskeleton based on a gear structure

Abstract

This invention discloses a bionic knee exoskeleton based on a gear structure, comprising a lower leg exoskeleton assembly, a thigh exoskeleton assembly, a drive mechanism, and a knee joint bionic mechanism. The drive mechanism is connected to the knee joint bionic mechanism and disposed between the lower leg and thigh exoskeleton assemblies. The knee joint bionic mechanism includes a planetary gear mechanism and a three-stage gear mechanism, which are connected by a planetary carrier. The planetary gear mechanism and the three-stage gear mechanism are connected to the drive mechanism via an output shaft. This design effectively simulates the movement characteristics of the human knee joint, reducing the relative sliding between the strap and the body caused by joint misalignment, as well as the shearing force exerted by the strap on the body. Furthermore, as a rehabilitation training device, the knee joint requires a large assist force; this device, through its gear structure, effectively improves energy utilization efficiency and meets the demand for a high-torque drive device.

Description

Technical Field

[0001] This invention relates to physiotherapy devices, and more particularly to a bionic knee exoskeleton based on a gear structure. Background Technology

[0002] With the increasing aging of society, the number of patients with motor dysfunction caused by cardiovascular diseases such as stroke and traffic accidents is increasing year by year. The use of rehabilitation exoskeleton robots has effectively alleviated the pressure on the rehabilitation industry and improved the efficiency of patient training. However, the complexity of the physiological structure of the knee joint makes it easy for patients to experience up-and-down sliding of their legs at the straps of the rehabilitation robot when walking while wearing it, due to the misalignment of the rotation center. Furthermore, the shearing force generated at the straps due to the difference in rotation axis between the leg and the exoskeleton affects the comfort of the patient. Currently, most rehabilitation robots on the market treat the knee joint as a single-axis joint. While this has the advantage of low cost, the strap structure exhibits significant slippage and shearing force, resulting in relatively poor comfort. Additionally, researchers have developed bionic knee joints based on four-bar linkages and cam mechanisms. Although these can simulate the physiological movement characteristics of the human knee joint, their transmission efficiency is low, making them more suitable for passive knee joint applications. For patients with lower limb dysfunction, who require assistance to complete knee flexion and extension movements, the knee joint needs to be set to an assisted mode.

[0003] There is an urgent need for a bionic knee exoskeleton that can address the poor comfort caused by misalignment of the rotation axis and the inability of bionic knee joint structures to provide large torque assistance. Summary of the Invention

[0004] Purpose of the Invention: The purpose of this invention is to address the shortcomings of existing rehabilitation training robots in terms of joint misalignment and insufficient additional shear force at the knee joint due to poor biomimicry. It also aims to provide a large torque to the knee joint, assisting patients in passive training, by providing a gear-based bionic knee exoskeleton. Technical Solution: The gear-based bionic knee exoskeleton of this invention includes a lower leg exoskeleton assembly, a thigh exoskeleton assembly, a drive mechanism, and a knee joint bionic mechanism. The drive mechanism is connected to the knee joint bionic mechanism and located between the lower leg and thigh exoskeleton assemblies. The knee joint bionic mechanism includes a planetary gear mechanism and a three-stage gear mechanism, which are connected by a planetary carrier. The planetary gear mechanism is connected to the drive mechanism.

[0005] The device consists of four parts: a thigh exoskeleton assembly, a lower leg exoskeleton assembly, a knee joint bionic mechanism, and a drive mechanism. The knee joint bionic mechanism is designed based on the physiological characteristics of the human knee joint and the instantaneous changes in its rotation center. It simulates the relative rolling and sliding between the tibia and femur in the knee joint. A planetary gear mechanism simulates the relative rolling of the tibia around the femur, and a three-stage gear mechanism simulates the relative sliding. The combined motion of these two mechanisms serves as the motion characteristic of the lower leg, driving the movement of the lower leg. This effectively reduces discomfort caused by misalignment between the exoskeleton and the rotation axis of the human knee joint during patient walking, thus reducing the impact on training effectiveness. Furthermore, the high transmission efficiency of the gear mechanism makes it more suitable for applications requiring the transmission of high torque power at the knee joint of rehabilitation robots.

[0006] Furthermore, the lower leg exoskeleton assembly includes: a lower leg wear fastener and a lower leg connecting rod; the lower leg wear fastener is worn on the human lower leg, and one end of the lower leg connecting rod is fixed to the knee joint bionic structure, and the other end is connected to the lower leg wear fastener;

[0007] Furthermore, the thigh exoskeleton assembly includes: a thigh wearable fixation device and a thigh connecting rod; the thigh wearable fixation device is worn on the human thigh, and one end of the thigh connecting rod is fixed to the knee joint bionic structure, and the other end is connected to the thigh wearable fixation device;

[0008] Furthermore, the drive mechanism, which is a DC brushless motor module, is connected to the knee joint bionic mechanism by bolts;

[0009] Furthermore, the knee joint bionic mechanism includes a planetary gear mechanism and a three-stage gear mechanism; the sun gear in the planetary gear mechanism is connected to the output shaft of the motor, and the rotational motion of the planetary carrier simulates the relative rolling of the tibia around the femur; the three-stage gear mechanism is fixed on the side of the planetary carrier away from the planetary gear structure, its first gear is connected to the output shaft of the motor, the second gear plays a role in reversing, and the third gear retains a section of tooth shape for meshing and is connected to the lower leg connecting rod to simulate the relative sliding generated by the rotation of the tibia around the femur.

[0010] Furthermore, the knee joint bionic structure includes a planetary gear mechanism and a three-stage gear mechanism; the planetary gear mechanism includes a drive shaft, a sun gear, three planet gears, an internal gear ring, and a planet carrier; the drive shaft is a stepped shaft, fixed to the output end of the DC brushless motor module by bolts, serving as the power source for the planetary gear mechanism; the drive shaft is provided with two keyways, which are used to connect the sun gear and the first gear in the three-stage gear structure, respectively, to ensure that the two gears rotate at the same speed; there are three planet gears, arranged at 120° intervals between the sun gear and the internal gear ring, mainly to balance the load; the inner side of the internal gear ring has involute teeth that mesh with the planet gears, and the shape of its outer edge depends on the shape of the motor, mainly to facilitate reasonable fixation of the motor; on the side of the internal gear ring near the lower leg connecting rod, a groove is cut at a 120° angle to the vertical axis, and this mechanical limit is used to ensure the stability of the standing phase.

[0011] Furthermore, the planetary carrier is the intermediate link connecting the planetary gear mechanism and the three-stage gear mechanism, and its shape is designed according to its function. First, one side includes three cylindrical bosses spaced 120° apart, on which miniature bearings are placed. The planetary gears are interference-fitted with the bearings, and the revolution of the planetary gears drives the planetary carrier to rotate. A circular through hole is provided at the center of the three cylindrical bosses for placing a deep groove ball bearing. The outer ring of the bearing is transition-fitted with the circular through hole, and the inner ring of the bearing is interference-fitted with the drive shaft. The other side of the planetary carrier is the three-stage gear mechanism, which has two bosses on its surface for fixing the second and third gears. In addition, an annular groove is provided on each cylindrical boss for axially fixing the gears.

[0012] Furthermore, the knee joint bionic structure includes a planetary gear mechanism and a three-stage gear mechanism, wherein the three-stage gear mechanism includes a drive shaft, a planet carrier, a first gear, a second gear, and a third gear.

[0013] Furthermore, the drive shaft of the three-stage gear mechanism is the same as the drive shaft in the planetary gear mechanism, passing through a pre-drilled hole on the planetary carrier. The first gear is fixed to the drive shaft by a flat key, ensuring that its rotational speed is the same as that of the planetary gear mechanism. Two cylindrical bosses on one side of the planetary carrier, located on the third-stage gear mechanism, are used to fix the second and third gears, respectively. Miniature bearings are installed between the gear shaft and the bosses to reduce friction. At this time, the axis of the through hole and the axes of the two cylindrical bosses are on the same plane, and the distance between any two adjacent axes is the axial spacing of the gears installed according to the standard center distance. The second gear mainly serves to modify... The function of the variable-direction rotation of the final gear; the third gear is fixed to the lower leg link. Since the gear's rotation is not circular motion but reciprocating motion, only the tooth profile with a central angle of 0°-80° is retained. However, the non-working area of ​​the gear is not completely removed; its shape is rectangular, facilitating its fixation to the lower leg link with bolts. The gear's motion is transmitted to the lower leg link, driving the lower leg to perform flexion and extension movements. By superimposing the velocity of the planetary carrier in the planetary gear mechanism with the velocity of the third gear in the three-stage gear structure, the motion output to the lower leg link can be equivalent to the motion characteristics of the human knee joint. Through biomimetic design, the problem of poor comfort caused by joint misalignment is reduced.

[0014] Compared with the prior art, the beneficial effects of this invention are as follows: The knee exoskeleton based on the gear structure of this invention can effectively simulate the movement characteristics of the human knee joint, reduce the relative sliding between the strap and the human body caused by joint misalignment, and reduce the shear force generated by the strap on the human body; in addition, as a rehabilitation training device, the knee joint needs to provide a large auxiliary force, and this device can effectively improve the energy utilization efficiency through the gear structure, meeting the requirements for a high torque drive device. Attached Figure Description

[0015] Figure 1 This invention relates to a biomimetic knee exoskeleton (wearable) based on a gear structure;

[0016] Figure 2 This invention relates to a biomimetic knee exoskeleton (independent) based on a gear structure;

[0017] Figure 3 This is an exploded view of a biomimetic knee exoskeleton based on a gear structure according to the present invention.

[0018] Figure 4 This is a schematic diagram of a planetary gear structure according to the present invention;

[0019] Figure 5 These are front and back views of a planetary carrier structure according to the present invention;

[0020] Figure 6 This is a schematic diagram of a multi-stage gear structure according to the present invention;

[0021] Figure 7 This is a schematic diagram of a transmission shaft structure according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] The following is combined with Figures 1-7 This embodiment describes the bionic knee exoskeleton based on a gear structure.

[0024] like Figures 1 to 2 As shown, the bionic knee exoskeleton based on a gear structure includes: a thigh exoskeleton assembly, a lower leg exoskeleton assembly, a DC brushless motor module, and a knee joint bionic mechanism;

[0025] The lower leg exoskeleton assembly consists of two parts: a strap 7 for connecting the exoskeleton to the lower leg and a lower leg connecting rod 6. The upper end of the lower leg connecting rod 6 is connected to the third gear 50 by bolts, and the lower end is fixed to the lower leg strap 7 by bolts.

[0026] The thigh exoskeleton assembly consists of two parts: a strap 1 for connecting the exoskeleton to the thigh and a thigh link 2. The upper end of the thigh link 2 is fixed to the thigh strap 1 by bolts, and the lower end is fixed to the connection point of the internal gear ring 40 in the knee joint bionic mechanism 4 by bolts.

[0027] The DC brushless motor module 3 uses the Xiaomi motor joint module, which is fixed to the positioning hole reserved on the outer edge of the inner gear ring 40 with bolts.

[0028] The knee joint bionic mechanism 4 consists of two parts: a planetary gear mechanism and a three-stage gear mechanism.

[0029] Part 1: The planetary gear mechanism comprises five parts: an internal gear ring 40, a sun gear 41, a drive shaft 42, three planet gears 43, and a planet carrier 47. The gear module of the planetary gear mechanism is 0.5, and the material is 45# steel, which has been hardened to improve the surface hardness. The drive shaft 42 is a stepped shaft, bolted to the output end of the DC brushless motor module 3, transmitting the motor's torque as the power source for the planetary gear mechanism. Two keyways are provided on the drive shaft, and A-type flat keys 45 placed in the keyways connect the sun gear 41 to the first gear in the three-stage gear structure. Gear 52, wherein the sun gear 41 has 54 teeth; there are 3 planet gears 43, which are arranged at 120° intervals between the sun gear 41 and the internal gear ring 40, and the planet gears have 24 teeth; the internal gear ring 40 has 102 teeth, the inner side of which is the tooth that meshes with the planet gear, and the outer edge of which mainly serves to fix the motor. The outer radius of the device is larger than the radius of the joint motor. At the same time, a groove 44 is cut at the end away from the thigh link 2, along the axis of the thigh link 2 and at an angle of 120 degrees to the axis. This mechanical limit is used to ensure the stability of the standing phase and prevent knee hyperextension.

[0030] The planetary carrier 47 is the intermediate link connecting the planetary gear mechanism and the three-stage gear mechanism. Its shape is designed according to its function. First, one side includes three cylindrical bosses 470, 471, and 472 spaced 120° apart, on which miniature bearings are placed. The planetary gears 43 are interference-fitted with the bearings, and the revolution of the planetary gears drives the planetary carrier 47 to rotate. A circular through hole 475 is provided at the center of the three cylindrical bosses for placing a deep groove ball bearing. The outer ring of the bearing is transition-fitted with the circular through hole, and the inner ring of the bearing is interference-fitted with the drive shaft. The other side of the planetary carrier is the three-stage gear mechanism, which has two bosses 473 and 474 on its surface for fixing the second gear 51 and the third gear 50. In addition, an annular groove is provided on each cylindrical boss for axially fixing the gears.

[0031] Part Two: The three-stage gear mechanism comprises five parts: a drive shaft 42, a planetary carrier 47, a first gear 52, a second gear 51, and a third gear 50. All gears in the three-stage gear mechanism have a module of 0.5 and are installed with a standard center distance. The drive shaft 42 passes through the inner hole of a rolling bearing that mates with the planetary carrier 47 and is fixedly connected to the first gear 52 via a flat key 45. The first gear 52 rotates at the same speed as the drive shaft 42, and has 32 teeth. The second gear is fixed to a cylindrical boss 474 on the planetary carrier 47, and the third gear 50 is fixed to a cylindrical boss 473 on the planetary carrier 47. At this point, the axis of the through hole 475, the axis of the cylindrical boss 473, and the axis of the cylindrical boss 474 are on the same plane, and the distance between any two adjacent axes is the axis spacing of the gears installed according to the standard center distance. The second gear 51 has 28 teeth and mainly serves to change the rotation direction of the end gear. The third gear has 144 teeth. Since the gear rotation is not circular but reciprocating, only a portion of the tooth profile with a central angle of 80° is retained. However, the non-working area of ​​the gear is not completely removed; its retained shape is rectangular. The third gear 50 is fixed to the small leg connecting rod 6 with bolts. The cover 53 is fixed to the inner gear ring 40 with bolts. The through hole in its center is used to house a deep groove ball bearing, and the bearing's inner diameter is fitted with the drive shaft 42.

[0032] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A bionic knee exoskeleton based on gear structure, characterized in that, It includes a lower leg exoskeleton assembly, a thigh exoskeleton assembly, a drive mechanism, and a knee joint bionic mechanism (4). The drive mechanism is connected to the knee joint bionic mechanism (4) and is located between the lower leg exoskeleton assembly and the thigh exoskeleton assembly. The knee joint bionic mechanism includes a planetary gear mechanism and a three-stage gear mechanism (5). The planetary gear mechanism and the three-stage gear mechanism (5) are connected by a planet carrier. The planetary gear mechanism is connected to the drive mechanism. A planetary gear mechanism is used to simulate the relative rolling of the tibia around the femur, and a three-stage gear mechanism is used to simulate the relative sliding caused by the rotation of the tibia around the femur. The planetary gear mechanism includes: a drive shaft (42), a sun gear (41), three planet gears (43), an internal gear ring (40), and a planet carrier (47); the drive shaft (42) is connected to the sun gear (41) via an A-type key (45), and the three planet gears (43) are distributed at 120° intervals between the sun gear (41) and the internal gear ring (40). The internal gear ring (40) has an involute tooth profile inside. The three-stage gear mechanism (5) includes a drive shaft (42), a planetary carrier (47), a first gear (52), a second gear (51), and a third gear (50). The drive shaft (42) in the three-stage gear mechanism is the same shaft as the drive shaft (42) in the planetary gear. The first gear (52) is fixed to the drive shaft (42) by a flat key. The second gear (51) and the third gear (50) are respectively fixed to two cylindrical bosses on the planetary carrier (47) near the three-stage gear mechanism (5). The third gear retains only the tooth profile with a central angle of 80°, and the rest is cut into a rectangle for fixing to the lower leg connecting rod (6). The sun gear (41) in the planetary gear mechanism is connected to the output end of the motor via a transmission shaft (42); the three-stage gear mechanism (5) is fixed on the side of the planetary carrier (47) away from the planetary gear mechanism, its first gear (52) is connected to the output end of the motor via a transmission shaft (42), the second gear (51) plays the role of reversing, and the third gear (50) retains a section of tooth profile for meshing and is connected to the lower leg connecting rod (6).

2. The bionic knee joint exoskeleton according to claim 1, characterized in that, The lower leg exoskeleton assembly includes: a lower leg wear fixation piece and a lower leg connecting rod (6); the lower leg wear fixation piece is used to be worn on the human lower leg, and one end of the lower leg connecting rod (6) is fixed to the knee joint bionic mechanism (4), and the other end is connected to the lower leg wear fixation piece.

3. The bionic knee joint exoskeleton according to claim 1, characterized in that, The thigh exoskeleton assembly includes: a thigh wear fastener and a thigh link (2); the thigh wear fastener is worn on the human thigh, and one end of the thigh link is fixed to the knee joint bionic mechanism (4), and the other end is connected to the thigh wear fastener.

4. The bionic knee joint exoskeleton according to claim 1, characterized in that, The drive mechanism is a DC brushless motor module (3), which is connected to the knee joint bionic mechanism (4) by bolts.

5. The bionic knee joint exoskeleton according to claim 1, characterized in that, The drive shaft (42) is a stepped shaft, with one end connected to the output end of the drive mechanism. It contains two keyways, and the sun gear (41) and the first gear (52) are fixed to it by a flat key.

6. The bionic knee joint exoskeleton according to claim 1, characterized in that, The inner side of the internal gear ring (40) is an involute tooth shape, and the outer edge shape is designed with reference to the drive mechanism. On the side of the internal gear ring near the lower leg connecting rod (6), a groove is cut at an angle of 120° with the vertical axis.

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