A bionic joint driven by twisted-pair wire with variable stiffness and transmission ratio

Abstract

The present invention relates to a twisted-wire-driven bionic joint with variable stiffness and variable transmission ratio, comprising a first joint segment and a second joint segment. A driving component is used to drive the first and second twisted wires to respectively perform twisting contraction and untwisting and relaxation to pull a turntable to rotate so as to drive the second joint segment to swing. At the same time, a first wire splitter and a second wire splitter with a wire splitting function are respectively arranged on the first and second twisted wires, and the positions of the first and second wire splitters are adjusted to adjust the lengths of the twisted wire segments of the first and second twisted wires. The transmission ratio between the first and second twisted wires is adjusted by arranging an adjusting gear to mesh with the first and second wire splitters, thereby realizing the adjustment of the stiffness of the first and second twisted wires.

Description

Technical Field

[0001] The invention relates to the technical field of bionic joint manufacturing, in particular to a twisted-pair-driven bionic joint with variable stiffness and variable transmission ratio. Background Art

[0002] Traditional joint drives generally use hydraulic drive, motor direct drive and other drive methods. Hydraulic drive generally uses mineral oil as the working medium. The relative moving surfaces can lubricate themselves, have a long service life, and can provide large power output. It is widely used in weight-enhanced exoskeletons, but it requires additional hydraulic source parts, resulting in heavy system weight, poor portability, poor wearing comfort, difficulty in achieving high-precision force control, and insufficient drive compliance.

[0003] With the good design of high-performance adaptive force-position control algorithms, motor control technology is becoming more and more mature. It can provide a large assist torque at the joints and achieve good following of the human body's gait. However, the direct-drive motor drive system has the disadvantages of large structural stiffness, the need for reduction gears, and large size and inertia. In order to improve the driving compliance and wearing comfort of the motor drive system, a rope drive system consisting of a motor combined with a winch, ropes, etc. is currently often used. It has the characteristics of long-distance power transmission, light weight, simple installation, and high compliance. However, it is easily limited by its own structural characteristics and can only provide a linear driving force parallel to the body. It is easy to deform under force, lacks bionic compliance, and its wearing comfort needs to be improved.

[0004] As the design concept of flexible drive becomes more mature, flexible drive technologies such as pneumatic muscle drive, deformation material drive, and series elastic drive are widely used in the design of exoskeleton drive systems; pneumatic artificial muscle converts pneumatic power into tension. Compared with traditional pneumatic cylinders, it has the characteristics of high force-to-weight ratio, no mechanical parts, low compressed air consumption and low cost, and good flexibility, but the power supply system is huge, the drive is highly nonlinear, and it is difficult to control accurately; deformation material drive systems such as thermal deformation and power-on deformation have the advantages of high flexibility and novel drive methods, but the material output is small, there is return hysteresis, and the control system is complex; the series elastic drive system increases the flexibility of the drive system through the deformation of the elastic body, improves the driving performance such as human-computer interaction, energy efficiency, impact resistance, and reversible drive, but has defects such as large size, high weight, complex structural design, and complex installation. In recent years, the stranded wire drive has attracted widespread attention due to its characteristics such as lightweight, high energy efficiency, high flexibility, and high transmission ratio. However, the transmission ratio is determined by the length of the stranded wire and is not adjustable, which seriously affects its driving performance. For example, the Chinese patent application publication number is "CN112370314B", and the patent name is "A tensioned flexible ankle joint wearable power-assisting device based on twisted pair drive", which includes a foot support plate, a flexible joint, and an ankle wearable component. The lower end of the flexible joint is connected to the ankle wearable component, and the upper end of the flexible joint is connected to the twisted pair drive part, wherein the twisted pair drive part includes a motor fixing plate, a motor is installed on the motor fixing plate, the lower end of the motor is connected to a coupling, and the coupling is connected to a driving shaft, and a gear II is fixedly connected to the driving shaft. The shaft is fixed with a wire ring II, the gear II is meshingly connected with the gear I, the gear I is connected to the driven shaft through a small bearing seat, one end of a large bearing seat is fixed to the lower end of the gear I, and the other end of the large bearing seat is connected to the wire ring I. The above driving method cannot be comparable to the biological joint driving method. The biological joint drive has good joint flexibility, and the joint torque, speed and stiffness have good adaptability. How to combine it with the biological muscle movement mechanism to develop a lightweight, highly flexible, high-energy-efficiency variable stiffness and variable transmission ratio muscle-like bionic drive joint is particularly important. Summary of the invention

[0005] The problem solved by the present invention is how to develop a lightweight, highly flexible and energy-efficient muscle-like bionic joint.

[0006] To solve the above problems, the present invention provides a twisted-wire-driven bionic joint with variable stiffness and variable transmission ratio, comprising a first joint segment and a second joint segment, the second joint segment being hinged and swinging with the first joint segment, a turntable for driving the second joint segment to swing is provided at a hinged position of the second joint segment corresponding to the first joint segment, the turntable is connected with a first twisted wire and a second twisted wire that pulls the turntable to rotate, a driving component is provided on the first joint segment, the first twisted wire and the second twisted wire are connected to the driving component, when the driving component drives the first twisted wire to twist and contract, the driving component drives the second twisted wire to untwist and relax, the turntable rotates clockwise under the traction of the first twisted wire to drive the second joint segment to swing forward; when the driving component drives the first twisted wire to twist and contract, the driving component drives the second twisted wire to untwist and relax, the turntable rotates clockwise under the traction of the first twisted wire to drive the second joint segment to swing forward; When the dynamic component drives the second strand to twist and contract, the driving component drives the first strand to untwist and relax, and the turntable rotates counterclockwise under the traction of the second strand to drive the second joint segment to swing in the opposite direction; the first strand and the second strand are respectively connected with the first wire divider and the second wire divider for dividing and adjusting the length of the strands, and the first wire divider and the second wire divider are smoothly connected to the first joint segment, and the first joint segment is provided with an adjustment gear corresponding to the first wire divider and the second wire divider for adjusting the transmission ratio of the first strand and the second strand, and the first wire divider and the second wire divider are respectively provided with adjustment teeth meshing with the adjustment gear on the side walls of the adjustment gears.

[0007] The beneficial effects of the present invention are as follows: a driving assembly is used to drive the first strand and the second strand to respectively perform twisting contraction and untwisting relaxation to pull the turntable to rotate and drive the second joint segment to swing; at the same time, a first wire splitter and a second wire splitter with a wire splitting function are respectively provided on the first strand and the second strand, and the positions of the first wire splitter and the second wire splitter are adjusted to adjust the lengths of the stranded wire segments of the first strand and the second strand; the transmission ratio between the first strand and the second strand is adjusted by providing an adjusting gear that meshes with the first wire splitter and the second wire splitter, thereby achieving the adjustment of the stiffness of the first strand and the second strand.

[0008] Preferably, a rotating pin is fixed on the adjusting gear corresponding to the first joint segment, a rotating shaft hole is opened at the center of the adjusting gear, and the adjusting gear is rotatably sleeved on the rotating pin.

[0009] Preferably, a first locking groove is provided on the side wall of the rotating pin shaft, and a second locking groove is provided on the inner wall of the rotating shaft hole of the adjusting gear. The first locking groove and the second locking groove are combined to form a self-locking groove for accommodating a locking pin. A locking pin is movably inserted in the self-locking groove. By pulling out the locking pin and rotating the adjusting gear to adjust the position of the first wire splitter and the second wire splitter, the transmission ratio and the stiffness of the first and second strands of the wire can be adjusted. After the adjustment is completed, the locking pin is inserted into the self-locking groove and locked.

[0010] Preferably, an adjusting motor is provided above the adjusting gear corresponding to the first joint section through a motor mounting bracket, the output end of the adjusting motor is connected to a linkage shaft, and a coupling sleeve adapted to the linkage shaft is integrally provided at the rotating shaft hole corresponding to the adjusting gear, and the adjusting motor is connected and driven by the adjusting gear through the linkage shaft and the coupling sleeve.

[0011] Preferably, the side wall of the turntable is concave to form a wire guide groove, and a wiring pin is provided in the wire guide groove. One end of the first stranded wire and the second stranded wire are respectively connected to the wiring pin. The first stranded wire and the second stranded wire are respectively distributed along both sides of the turntable and connected to the driving assembly, so that the first stranded wire and the second stranded wire cooperate to drive the turntable to rotate clockwise or counterclockwise, pulling the second joint segment to swing.

[0012] Preferably, the drive assembly includes a drive motor, a first drive gear, a second drive gear, a coupling and a connector, wherein the drive motor is fixed to the first joint segment through a mounting seat, the first drive gear and the second drive gear are respectively rotatably connected to the first joint segment through a gear seat, the first drive gear is meshed with the second drive gear, the output end of the drive motor is connected to the first drive gear through a coupling to drive the first drive gear to rotate, the first drive gear is connected to the first twisted wire through a connector, and the second drive gear is connected to the second twisted wire through a connector; so that the first drive gear and the second drive gear respectively and simultaneously drive the first twisted wire and the second twisted wire to perform opposite twisting movements, thereby driving the turntable to rotate clockwise or counterclockwise.

[0013] Preferably, the drive motor is a brushless DC motor.

[0014] Preferably, the first twisted wire and the second twisted wire are both composed of multiple single wires, and the first splitter and the second splitter are respectively provided with multiple wiring holes for the single wires to pass through along the threading direction of the first twisted wire and the second twisted wire, and each single wire of the first twisted wire and the second twisted wire is respectively connected through the wiring holes of the first splitter and the second splitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of a specific embodiment 1 of the present invention;

[0016] Figure 2 for Figure 1 A magnified view of the structure on the first joint segment;

[0017] Figure 3 It is a side schematic diagram of a specific embodiment 1 of the present invention;

[0018] Figure 4 This is an exploded view of the installation of the adjustment gear and the locking pin in the specific embodiment 1 of the present invention;

[0019] Figure 5 It is a structural schematic diagram of the first splitter or the second splitter in the specific embodiment 1 of the present invention;

[0020] Figure 6 It is a structural schematic diagram of specific embodiment 2 of the present invention;

[0021] Figure 7 This is an exploded view of the installation of the adjusting gear and the adjusting motor in the specific embodiment 2 of the present invention;

[0022] Figure 8 It is the experimental principle diagram of the present invention;

[0023] Fig. 9 Figure 1 is a diagram of the experimental platform built for the present invention;

[0024] Fig.10 This is a comparison diagram of the theory and practice of the experimental stranded wire segment 340 mm of the present invention;

[0025] Fig.11 This is an experimental curve diagram of transmission ratios of different stranded wire segment lengths used in the experiment of the present invention;

[0026] Fig.12 This is the force distribution diagram of the stranded wire limit of the experimental drive assembly of the present invention.

[0027] Description of reference numerals:

[0028] 1. First joint section; 2. Second joint section; 3. Turntable; 3.1. Lead groove; 3.2. Wiring pin; 4. First stranded wire; 5. Second stranded wire; 6. Driving assembly; 6.1. Driving motor; 6.2. First driving gear; 6.3. Second driving gear; 6.4. Coupling; 6.5. Wiring connector; 7. First wire distributor; 8. Second wire distributor; 9. Adjusting gear; 9.1. Rotating shaft hole; 9.2. Second locking groove; 9.3. Coupling sleeve; 10. Adjusting tooth path; 11. Rotating pin; 11.1. First locking groove; 12. Locking pin; 13. Adjusting motor; 13.1. Linkage shaft; 14. Wiring channel. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiment 1

[0031] like Figure 1-5As shown, a variable stiffness and variable transmission ratio twisted-wire driven bionic joint comprises a first joint segment 1 and a second joint segment 2, wherein the second joint segment 2 is hingedly connected and swung with the first joint segment 1, specifically: a hinge hole is provided on the first joint segment 1, and a hinge column adapted to the hinge hole is integrally provided on the second joint segment 2, and the second joint segment 2 is hingedly connected and swung with the first joint segment 1 through the hinge hole and the hinge column to form a biological joint; and, in order to make the swing of the second joint segment 2 and the first joint segment 1 closer to the movement of a biological joint, in this specific embodiment, a turntable 3 for driving the second joint to swing is integrally provided at the hinge between the second joint segment 2 and the first joint segment 1, and the turntable 3 is connected with a first twisted wire 4 and a second twisted wire 5 for pulling the turntable 3 to rotate, and in order to realize that the first twisted wire 4 and the second twisted wire 5 pull the turntable 3 to rotate, the first twisted wire 4 and the second twisted wire 5 are both composed of a plurality of single wires. The first strand 4 and the second strand 5 of this specific embodiment are composed of two single wires, and the first strand 4 and the second strand 5 are respectively connected with a first wire splitter 7 and a second wire splitter for separating the strands into single wires. The first joint segment 1 is provided with a driving component 6, and the first strand 4 and the second strand 5 are respectively connected with the first wire splitter 7 and the second wire splitter 8 and connected to the driving component 6 for driving. Before the first strand 4 and the second strand 5 are connected to the driving component 6, the first strand 4 and the second strand 5 are rotated in the same rotation direction to produce pre-twisting, so as to ensure that after the first strand 4 and the second strand 5 of the driving component 6 are connected, the first strand 4 and the second strand 5 can be in the state of twisting contraction and untwisting relaxation respectively during the rotation process; at the same time, the driving action of the driving component 6 and the first strand 4 and the second strand 5 of this specific embodiment is:

[0032] A. When the driving assembly 6 drives the first strand 4 to twist and contract, the driving assembly 6 drives the second strand 5 to untwist and relax, and the turntable 3 rotates clockwise under the traction of the first strand 4 to drive the second joint segment 2 to swing forward;

[0033] B. When the driving assembly 6 drives the second strand 5 to twist and contract, the driving assembly 6 drives the first strand 4 to untwist and relax, and the turntable 3 rotates counterclockwise under the traction of the second strand 5 to drive the second joint segment 2 to swing in the opposite direction;

[0034] The first wire splitter 7 and the second wire splitter are respectively arranged on the first stranded wire 4 and the second stranded wire 5, so that the first stranded wire 4 forms a stranded wire segment corresponding to the first wire splitter 7 and the driving component 6, and the portion corresponding to the first wire splitter 7 and the turntable 3 forms a straight section under the action of the first wire splitter 7; the second stranded wire 5 forms a stranded wire segment corresponding to the second wire splitter 8 and the driving component 6, and the portion of the second stranded wire 5 corresponding to the second wire splitter 8 and the driving component 6 forms a straight section; thereby, the stiffness of the first stranded wire 4 and the second stranded wire 5 can be adjusted by adjusting the stranded wire segment lengths of the first stranded wire 4 and the second stranded wire 5, and the first separator and the second separator are smoothly connected to the first joint segment 1 along the thread trajectories of the first stranded wire 4 and the second stranded wire 5; at the same time, in order to make the second joint segment 2 swing more similarly In this specific embodiment, an adjusting gear 9 is rotatably connected between the first joint segment 1 corresponding to the first wire divider 7 and the second wire divider 8. The specific structure is: a rotating pin 11 is fixed on the adjusting gear 9 corresponding to the first joint segment 1, and a rotating shaft hole 9.1 is opened at the center of the adjusting gear 9, and the adjusting gear 9 is rotatably sleeved on the rotating pin 11; and, one side of the adjusting gear 9 corresponding to the first wire divider 7 and the second wire divider 8 is integrally provided with an adjusting tooth path 10 meshing with the adjusting gear 9, and the positions of the first wire divider 7 and the second wire divider 8 are adjusted by rotating the adjusting gear 9, thereby adjusting the transmission ratio of the first strand 4 and the second strand 5. The transmission ratio in this specific embodiment is the ratio of the displacement of the twisting contraction of the first strand 4 and the second strand 5 to the number of twisting turns;

[0035] Furthermore, a first locking groove 11.1 is distributed on the side wall of the rotating pin shaft 11, and a second locking groove 9.2 is opened on the inner wall of the rotating shaft hole 9.1 of the adjusting gear 9. The first locking groove 11.1 and the second locking groove 9.2 are combined to form a self-locking groove for accommodating a locking pin 12. A locking pin 12 is movably inserted in the self-locking groove. By pulling out the locking pin 12, the adjusting gear 9 is rotated to adjust the position of the first wire splitter 7 and the second wire splitter 8, thereby adjusting the transmission ratio and the wire stiffness of the first stranded wire 4 and the second stranded wire 5; after the adjustment is completed, the locking pin 12 is inserted into the self-locking groove and locked.

[0036] Further, the drive assembly 6 includes a drive motor 6.1, a first drive gear 6.2, a second drive gear 6.3, a coupling 6.4 and a connector 6.5, wherein the drive motor 6.1 described in this specific embodiment is a DC brushless motor, the drive motor 6.1 is fixed to the first joint segment 1 through a mounting seat, the first drive gear 6.2 and the second drive gear 6.3 are respectively rotatably connected to the first joint segment 1 through a gear seat, the first drive gear 6.2 is meshed with the second drive gear 6.3, the output end of the drive motor 6.1 is connected to the first drive gear 6.2 through a coupling 6.4 to drive the first drive gear 6.2 to rotate, the first drive gear 6.2 is connected to the first twisted wire 4 through a connector 6.5, and the second drive gear 6.3 is connected to the second twisted wire 5 through the connector 6.5; so that the first drive gear 6.2 and the second drive gear 6.3 respectively and simultaneously drive the first twisted wire 4 and the second twisted wire 5 to perform opposite twisting motions, driving the turntable 3 to rotate clockwise or counterclockwise.

[0037] Furthermore, the first twisted wire 4 and the second twisted wire 5 are each composed of multiple single wires, and the first splitter 7 and the second splitter 8 are respectively provided with multiple wiring channels 14 for the single wires to pass through along the threading direction of the first twisted wire 4 and the second twisted wire 5. Each single wire of the first twisted wire 4 and the second twisted wire 5 is respectively connected through the wiring channels 14 of the first splitter 7 and the second splitter 8, thereby realizing the function of splitting the first twisted wire 4 and the second twisted wire 5. Specific embodiment 2

[0039] The difference between this specific embodiment and specific embodiment 1 is that Figure 6-7 As shown, an adjusting motor 13 is provided above the adjusting gear 9 corresponding to the first joint segment 1 through a motor mounting bracket, and a linkage shaft 13.1 is connected to the output end of the adjusting motor 13, and a coupling sleeve 9.3 adapted to the linkage shaft 13.1 is integrally provided at the rotating shaft hole 9.1 corresponding to the adjusting gear 9, and the adjusting motor 13 is connected and driven with the adjusting gear 9 through the linkage shaft 13.1 and the coupling sleeve 9.3. The adjusting motor 13 is rotated to adjust the adjusting gear 9, and the sliding distance of the first separator and the second separator is adjusted more accurately and more intelligently.

[0040] Experimental principle:

[0041] like Figure 8 The calculation formula for the twist shrinkage displacement of the stranded wire shown is:

[0042]

[0043] Where Δp is the twist contraction displacement, F i is the rope tension, K is the rope stiffness, and θ is the twist angle value, i.e. the radian value.

[0044] Experiment 1

[0045] Build as Fig. 9 The experimental platform shown in the figure consists of a displacement sensor, a slider, a slide rail, a tension sensor, a block, a distributor, a bearing, a bearing seat, a coupling, a DC motor, a magnetic encoder, and a twisted wire. Through the data returned by the displacement sensor and the magnetic encoder, the experimental platform can explore the relationship between the number of motor rotations and the linear displacement of the slider, and explore the change of the transmission ratio (the ratio of the twist contraction displacement to the number of twist turns) N; through the data returned by the tension sensor, the platform can measure different twisted wire states, explore the ultimate force of the twisted wire, and thus obtain the change of the stiffness of the drive device.

[0046] First, the total length of the twisted pair is set to 650mm, and the length of the twisted wire segment is set to 340mm. The motor is controlled by a speed loop, and the speed is set to 60r / min. When the motor is started, the twisted wire twists along a fixed direction. In order to eliminate the influence of a single experiment on the experimental structure, the experiment is repeated five times. After one experiment is completed, the motor rotates to restore the twisting to the initial parallel position. At the same time, in order to make the number of motor rotations constant before recording data each time, a block is set at the slider displacement of 150mm. When the slider is blocked, the experiment stops. Fig.10 Conclusions from the experimental data shown:

[0047] 1) The actual curve is the experimental data curve with a stranded wire section of 340 mm, because the 2N tension of the displacement sensor is relatively small;

[0048] 2) The data graph without considering the change of radius shows the relationship between the number of revolutions and the displacement when the change of rope radius is not considered. It can be seen that with the increase of the number of motor revolutions, there is a certain deviation between the theoretical contraction length of the stranded wire and the actual length. Specifically, the theoretical contraction value is smaller than the actual contraction value, and the difference value increases with the increase of the number of twisting turns. However, from the perspective of the geometric shape of the line, the change of the line itself is consistent with the actual situation, which also explains the correctness of the error analysis made for the theoretical model to a certain extent;

[0049] 3) The data considering the change of radius highlights the relationship between the number of revolutions and displacement when the radius of the stranded wire is changed from the initial value of 0.75mm to the final actual value of 0.82mm without considering the change of radius. It can be seen that the model curve does not fit the actual situation well in the low-turn segment, which is specifically manifested in that the theoretical contraction value is smaller than the actual contraction value. However, when the number of motor rotations is greater than 45, the model fits the actual curve better. This experimental phenomenon shows that when the experiment is nearing the end, the radius of the stranded wire itself does not change significantly. At this time, the method of measuring the wire diameter and substituting it into the characteristic formula can better predict the twist contraction value. However, when the twist just occurs, the radius of the stranded wire will change significantly with the rotation of the motor. Since the wire diameter cannot be measured in real time, if only the final strand radius is substituted, errors will inevitably occur.

[0050] 4) In addition to the model considering the change of the strand radius, this specific embodiment also adopts the method of adding compensation for the increase and decrease due to the twisting of the strand itself in the later stage, and obtains Fig.10 Compared with modifying the final radius of the stranded wire, the curve when shrinkage compensation is added has a higher degree of fit with the actual curve in both the low-turn segment and the high-turn segment, and this method can avoid the error caused by the calculation or measurement of the final radius of the stranded wire. However, at present, no theoretical support for adding shrinkage compensation has been found. Therefore, after fitting and analyzing the experimental curves of the stranded wire segments of 340mm, 365mm and 440mm, a linear function of 0.30θ that is positively correlated with the number of motor rotations was obtained, and this function was used as shrinkage compensation.

[0051] Considering the deformation of the rope radius and assuming that the rope stiffness is large enough, the formula of the contraction displacement-twist number of the drive device can be modified by adding post-compensation as follows:

[0052]

[0053] The k value is related to the length of the stranded wire segment. When the length of the stranded wire segment is 340 mm, the k value is 0.30.

[0054] Experiment 2

[0055] In order to explore the change of the transmission ratio N of the stranded wire drive device with the change of the stranded wire segment length, under the condition that the original length of the twisted pair is constant (650mm), four experimental groups of 340mm, 365mm, 390mm and 415mm are set according to the different distances of the stranded wire segments. At the same time, 4 repeated experiments are carried out in each experimental group to verify the repeatability of the experiment and eliminate the error of a single experiment. In order to control the contraction length of the stranded wire to avoid over-twisting, a block is set at a distance of 150mm from the linear displacement of the slider. The experiment ends when the slider touches the block. The following results are obtained: Fig.11The experimental curve shown in the figure shows that by analyzing the data graph of the same stranded wire segment length, it can be found that when the slider produces the same displacement (for example, moving from 50mm to 100mm and from 100mm to 150mm), the number of motor rotations required is reduced. It can be seen that as the stranding continues, the transmission ratio of the drive device gradually increases. In addition, by comparing the data graphs of different stranded wire segment lengths, it can be found that when the slider produces the same displacement (for example, moving from 50mm to 100mm), the longer the stranded wire segment, the more stranded wire loops the drive device needs to produce, that is, the longer the stranded wire segment of the drive device, the smaller the transmission ratio of the drive device. The conclusion shows that in order to improve the displacement and contraction response speed of the device, a smaller stranded wire segment length should be selected as much as possible while avoiding over-twisting.

[0056] Experiment 3

[0057] In order to explore the relationship between the ultimate force of the stranded wire and the length of the stranded wire segment and the degree of stranding in the drive device, three experimental groups of 365mm, 390mm and 415mm were set up according to the different lengths of the stranded wire segments, and four sub-experimental groups of 25mm, 50mm, 75mm and 100mm were set up in each experimental group according to the different displacements of the slider. A total of 12 experimental groups were tested; when the movement of the slider is blocked by the block, the tension on the stranded wire will increase rapidly until the stranded wire breaks. The data returned by the tension sensor can be used to know the ultimate force of the stranded wire. By analyzing Fig.12 The following conclusions can be drawn from the data:

[0058] 1) For the four experimental groups with the same stranded wire segment length, the ultimate force of the stranded wire gradually decreases as its displacement increases when the slider is blocked, that is, for the same stranded wire segment length, as the degree of stranding increases, the ultimate force of the stranded wire decreases, that is, the stiffness of the drive system gradually decreases as the twisting proceeds.

[0059] 2) By analyzing the ultimate force data of different stranded wire segment lengths, it can be found that as the stranded wire segment length increases, when the slider is blocked at the same position, the greater the stranded wire segment length, the greater the ultimate force of the stranded wire, that is, the longer the stranded wire segment length, the greater the stiffness of the drive device. This conclusion helps to effectively select the appropriate stranded wire segment length when designing the drive device, ensuring that the transmission ratio of the drive device is within the working range while also making the stranded wire work in a safe range.

[0060] It can be seen from experiments that the shorter the length of the stranded wire segment, the greater the contraction displacement generated. If it is necessary to increase the speed of the second joint segment rotating in the positive direction, pull out the locking pin, rotate the adjusting gear counterclockwise, shorten the straight-line distance between the splitter and the connector to reduce the length of the stranded wire segment. At the same time, the increased stranded wire segment length can ensure more displacement margin. Finally, reinsert the locking pin to lock the current position of the splitter. The larger the stranded wire segment length, the greater the stiffness of the drive system. In the present invention, the system stiffness can be changed by adjusting the gears. For example, the second joint segment is overloaded during the forward rotation process. In order to ensure the safety of the system, the above-mentioned adjustment method is used to extend the stranded wire segment length of the second stranded wire and increase the stiffness of the stranded wire drive system.

[0061] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A twisted pair driven bionic joint with variable stiffness and variable transmission ratio, comprising a first joint segment (1) and a second joint segment (2), wherein the second joint segment (2) is hingedly connected to and swings with the first joint segment (1), characterized in that: A rotating disk (3) for driving the second joint segment (2) to swing is provided at a hinged portion of the second joint segment (2) corresponding to the first joint segment (1); the rotating disk (3) is connected with a first strand (4) and a second strand (5) for pulling the rotating disk (3) to rotate; a driving component (6) is provided on the first joint segment (1); the first strand (4) and the second strand (5) are connected to the driving component (6); when the driving component (6) drives the first strand (4) to twist and contract, the driving component (6) drives the second strand (5) to untwist and expand; the rotating disk (3) rotates clockwise under the traction of the first strand (4) to drive the second joint segment (2) to swing in the forward direction; when the driving component (6) drives the second strand (5) to twist and contract, the driving component (6) drives the first strand (4) to untwist and expand; The rotating disk (3) rotates counterclockwise under the traction of the second strand (5) to drive the second joint section (2) to swing in the opposite direction; the first strand (4) and the second strand (5) are respectively connected with a first wire splitter (7) and a second wire splitter (8) for splitting and adjusting the length of the strands; the first wire splitter (7) and the second wire splitter (8) are both smoothly connected to the first joint section (1); an adjusting gear (9) for adjusting the position of the first wire splitter (7) and the second wire splitter (8) to adjust the transmission ratio of the first strand (4) and the second strand (5) is provided between the first joint section (1) and the first wire splitter (7) and the second wire splitter (8); and an adjusting tooth path (10) meshing with the adjusting gear (9) is respectively provided on the side walls of the first wire splitter (7) and the second wire splitter (8) corresponding to the adjusting gear (9).

2. The variable stiffness and variable transmission ratio twisted pair driven bionic joint according to claim 1, characterized in that: A rotating pin shaft (11) is fixed on the first joint section (1) corresponding to the adjusting gear (9), a rotating shaft hole (9.1) is opened at the center of the adjusting gear (9), and the adjusting gear (9) is rotatably sleeved on the rotating pin shaft (11).

3. The twisted-pair-driven bionic joint with variable stiffness and variable transmission ratio according to claim 2, characterized in that: A first locking groove (11.1) is distributed on the side wall of the rotating pin shaft (11), and a second locking groove (9.2) is opened on the inner wall of the rotating shaft hole (9.1) of the adjusting gear (9). The first locking groove (11.1) and the second locking groove (9.2) are combined to form a self-locking groove, and a locking pin (12) is movably inserted in the self-locking groove.

4. The variable stiffness and variable transmission ratio twisted pair driven bionic joint according to claim 2, characterized in that: An adjusting motor (13) is arranged above the adjusting gear (9) corresponding to the first joint section (1) through a motor mounting bracket, the output end of the adjusting motor (13) is connected to a linkage shaft (13.1), a coupling sleeve (9.3) adapted to the linkage shaft (13.1) is integrally arranged at a rotating shaft hole (9.1) corresponding to the adjusting gear (9), and the adjusting motor (13) is connected and driven to the adjusting gear (9) through the linkage shaft (13.1) and the coupling sleeve (9.3).

5. A bionic joint with variable stiffness and variable transmission ratio driven by twisted pair cables according to claim 3 or 4, characterized in that: The side wall of the rotating disk (3) is integrally concave to form a wire guide groove (3.1), a wiring pin shaft (3.2) is provided in the wire guide groove (3.1), one end of the first stranded wire (4) and the second stranded wire (5) are respectively connected to the wiring pin shaft (3.2), and the first stranded wire (4) and the second stranded wire (5) are respectively distributed along two sides of the rotating disk (3) and connected to the driving component (6).

6. The variable stiffness and variable transmission ratio twisted pair driven bionic joint according to claim 5, characterized in that: The drive assembly (6) comprises a drive motor (6.1), a first drive gear (6.2), a second drive gear (6.3), a coupling (6.4) and a connector (6.5), wherein the drive motor (6.1) is fixed to the first joint segment (1) via a mounting seat, the first drive gear (6.2) and the second drive gear (6.3) are rotatably connected to the first joint segment (1) via a gear seat respectively, the first drive gear (6.2) is meshed with the second drive gear (6.3), the output end of the drive motor (6.1) is connected to the first drive gear (6.2) via a coupling (6.4) to drive the first drive gear (6.2) to rotate, the first drive gear (6.2) is connected to the first twisted wire (4) via a connector (6.5), and the second drive gear (6.3) is connected to the second twisted wire (5) via a connector (6.5).

7. The twisted-pair-driven bionic joint with variable stiffness and variable transmission ratio according to claim 6, characterized in that: The driving motor (6.1) is a DC motor.

8. The twisted-pair-driven bionic joint with variable stiffness and variable transmission ratio according to claim 7, characterized in that: The first twisted wire (4) and the second twisted wire (5) are both composed of a plurality of single wires. The first wire splitter (7) and the second wire splitter (8) are respectively provided with a plurality of wiring channels (14) for the single wires to pass through along the threading direction of the first twisted wire (4) and the second twisted wire (5). Each single wire of the first twisted wire (4) and the second twisted wire (5) is respectively connected through the wiring channels (14) of the first wire splitter (7) and the second wire splitter (8).

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