CN209966946U - Rope-driven lower limb joint rehabilitation mechanism mounted on wheelchair seat - Google Patents

Abstract

The utility model relates to a rope-driven lower limb joint rehabilitation mechanism arranged on a wheelchair seat, which comprises a main body part, a pedal mechanism, a rope driving device and a seat frame, wherein the upper end of the main body part is connected and fixed on the seat frame by two joint bases, and the lower end is connected with the pedal mechanism; the main body part comprises a joint base, three variable stiffness structures, a first joint, a guide rod, a linear push rod, a second joint, a third joint, a support frame and a linear push rod base, wherein the linear push rod is fixed on the linear push rod base along the vertical direction, and the guide rod is connected with the pedal mechanism. The mechanism is driven by a rope to pull a rotary joint to rotate around the axis, so that the motion trail of the rotary joint is controlled, the rigidity of the joint is changed through three rigidity-variable structures, and the decoupling of motion is realized.

Description

Rope-driven lower limb joint rehabilitation mechanism mounted on wheelchair seat

Technical Field

The utility model belongs to low limbs rehabilitation institution field specifically indicates a lower limbs joint rehabilitation institution of installing on wheelchair seat and by rope drive.

Background

The aging of the population and the increase of the number of the vulnerable groups such as limb disabilities make more and more people unable to walk independently due to the dysfunction. Paraplegia is a sensory disorder resulting from damage to the nervous system, resulting in loss of complete or partial motor function in the lower extremities of the body. However, the clinical application shows that the proper rehabilitation training can improve the symptoms of numbness of limbs and dyskinesia. The rehabilitation mechanism drives the lower limb joints to simply stretch and bend, so that blood circulation can be promoted, and the function can be improved. However, the existing lower limb rehabilitation mechanism can not accurately perform targeted rehabilitation training on hip joints, knee joints and ankle joints, and has the disadvantages of complex structure, heavy equipment and high price.

Application No. 201810270119.9 discloses a lower limb rehabilitation device capable of being carried on a wheelchair, wherein a thigh rod is driven by a pair of second driving devices arranged at the left and right ends of an H-shaped support frame through transmission of a link mechanism, a shank rod is driven by a disc motor arranged at the outer side of a knee joint, and a pedal plate is driven by a fourth driving device arranged on the shank rod, so that the motions of the thigh rod, the shank rod and the pedal plate are realized. Although the mechanism has the function of rehabilitation of lower limb joints, the four linear push rod motors make a control system complex, the mechanism is easy to self-lock, and the rehabilitation activity of the joints and the rehabilitation of a certain single joint are limited due to the length and the degree of freedom of the linear push rods. The drive is directly arranged on two sides of the human joint, and the safety can not be guaranteed.

SUMMERY OF THE UTILITY MODEL

The mechanism that can coordinate rehabilitation training to the independent joint rehabilitation training of low limbs joint and many joints is less to current, and three joint has coupling problem and structure complicacy when the simultaneous movement, and the drive mode of motor gear makes whole weight big, inefficiency, security poor etc. not enough, the utility model discloses the technical problem who solves provides a rehabilitation mechanism who has the independent joint training of low limbs joint and many joints and coordinate the training function. The mechanism is driven by a rope to pull a rotary joint to rotate around the axis, so that the motion trail of the rotary joint is controlled, the rigidity of the joint is changed through three rigidity-variable structures, and the decoupling of motion is realized.

The technical scheme of the utility model is that:

the utility model provides an install in recovered mechanism of rope drive low limbs joint of wheelchair seat, includes main part, pedal mechanism, rope drive arrangement and seat frame, its characterized in that:

the upper end of the main body part is connected and fixed on the seat frame by two joint bases, and the lower end of the main body part is connected with the pedal mechanism; the main body part comprises a joint base, three variable stiffness structures, a first joint, a guide rod, a linear push rod, a second joint, a third joint, a support frame and a linear push rod base, wherein the linear push rod is fixed on the linear push rod base along the vertical direction, and the guide rod is connected with the pedal mechanism; the two side surfaces of the upper end of the linear push rod base are respectively connected with a second joint and a joint driving end of a second variable stiffness structure, the other end of the second joint is connected with a joint driving end of a third variable stiffness structure, a joint input end of the third variable stiffness structure is connected with a first joint, the upper part of the first joint is connected with one joint base through a pin shaft, a joint input end of the third variable stiffness structure transmits power with a third motor through a bevel gear set, and the third motor is fixed at the lower part of the first joint;

the second joint and the third joint limit axial movement through a support frame, and the support frame simultaneously connects the second joint and a motor base of the second variable stiffness structure together;

the other end of the third joint is connected to the joint input end of the first variable stiffness structure, and the joint input end of the first variable stiffness structure is connected with the joint drive end of the second variable stiffness structure through the third joint; the joint driving end of the second variable stiffness structure transmits power with a second motor through a corresponding bevel gear set; the joint driving end of the first variable stiffness structure is in power transmission with a first motor through a corresponding bevel gear set, and a motor base of the first motor is connected with a joint base fixed on the seat frame;

the pedal mechanism comprises a gear, a pedal motor, a gear shaft, pedals, an angle limit switch, two pedal connecting frames, a screw rod, a pedal base and a sleeve base; the output end of the pedal motor is connected with a gear shaft through a gear set, the gear shaft is fixed on a pedal connecting frame, the upper parts of the two pedal connecting frames are symmetrically arranged on two sides of a screw rod, the lower end of the pedal connecting frame is fixed on the bottom surface of a pedal, and an angle limit switch is arranged on one side of the pedal connecting frame; the upper part of the pedal connecting frame is fixed with the pedal base at the same time, and a sleeve base for supporting and fixing the guide rod is arranged on the pedal base;

the rope driving device is provided with three groups of independent driving mechanisms which are connected in parallel, each driving mechanism is connected in the same way, each driving mechanism comprises a rope driving motor, a winding drum, a pulley block and a rope, and the pulley block comprises a horizontal pulley and a vertical pulley which are orthogonally distributed at the bottom of the front end of the seat frame; one end of the rope is fixed with the corresponding joint of the main body part, and the other end of the rope is wound on the winding drum; the winding drum is fixed on the output shaft of the rope driving motor.

The beneficial effects of the utility model reside in that:

the utility model discloses a wheelchair increases a rehabilitation mechanism, can drive the rehabilitation training of low limbs joint, the three joint of human low limbs, together with seat and main part joint, main part straight line push rod, can constitute the 6 pole mechanisms that have 3 degrees of freedom, utilize the kinematics to solve against the contrary, the rotation volume of movable rod spare and the amount of exercise of rope when can obtain the recovered low limbs joint according to the motion trail of running-board, as long as just can realize low limbs joint rehabilitation training through controlling corresponding motor, variable stiffness structure can change joint rigidity, ankle joint has been realized, single joint or the rehabilitation training of a plurality of joint coordination in knee joint and the hip joint. The mechanism can be used for active and passive rehabilitation training, the driving motor is positioned below the seat, safety and reliability are high, the rotary joint is pulled through a rope, and compared with a gear transmission mode, the mechanism is high in space utilization rate and small in mass, and the weight of the whole machine is greatly reduced due to the light design.

Drawings

The invention will be further described with reference to the accompanying drawings and specific embodiments:

FIG. 1 is a schematic view of the overall structure of a rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat of the present invention;

FIG. 2 is a schematic structural view of the main body of the rope-driven lower limb joint rehabilitation mechanism of the present invention mounted on a wheelchair seat;

FIG. 3 is a schematic structural view of the pedal mechanism of the rope-driven lower limb joint rehabilitation mechanism mounted on the wheelchair seat of the present invention;

FIG. 4 is a schematic structural view of the rope driving device of the rope-driven lower limb joint rehabilitation mechanism of the present invention mounted on a wheelchair seat;

FIG. 5 is a schematic view of a position of the mechanism for performing knee rehabilitation training;

FIG. 6 is another schematic view of the mechanism for performing knee rehabilitation training;

FIG. 7 is a schematic view of a position of the mechanism for performing hip rehabilitation training;

FIG. 8 is a schematic view of another position of the mechanism for performing hip rehabilitation training;

fig. 9 is a schematic structural view of a joint stiffness adjusting part in a variable stiffness structure according to an embodiment of the rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat of the present invention;

fig. 10 is a schematic view of the internal structure of a joint stiffness adjusting part in a variable stiffness structure according to an embodiment of the rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat of the present invention;

FIG. 11 is a schematic cross-sectional view of the structure of FIG. 7 taken along line A-A;

fig. 12 is a schematic perspective view of a sleeve of a variable stiffness structure according to an embodiment of the rope-driven lower limb joint rehabilitation mechanism of the present invention mounted on a wheelchair seat;

fig. 13 is a schematic structural view of a central shaft of a variable stiffness structure according to an embodiment of the rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat of the present invention;

(in the figure:

101. a first motor; 102. a first variable stiffness structure; 103. a second motor; 104. a guide bar; 105. a third motor; 106. a linear push rod; 107. a linear push rod base; 108. a second joint; 109. a first joint; 110. a joint base; 111. a support frame; 112. A third joint; 113. a second variable stiffness structure; 114. a third variable stiffness structure;

1021. a first conical disk; 1022. a torsion spring; 1023. a first disc spring; 1024. a central shaft; 1025. a first set of steel balls; 1026. a first slider; 1027. a second slider; 1028. a second disc spring; 1029. a second conical disk; 1030. a second set of steel balls; 1031. a left end cap; 1032. a first pressure spring; 1033. right-hand turning of the nut; 1034. a left-handed nut; 1035. a sleeve; 1036. a second pressure spring; 1037 a first shaft sleeve, 1038 a second shaft sleeve; 1039 a helical gear wheel;

21. a rope drive motor; 22. a reel; 23. a horizontal pulley; 24. a vertical pulley; 25. a rope;

30. a gear; 31. a pedal motor; 32. a gear shaft; 33. a foot pedal; 34. an angle limit switch; 35. a pedal connecting frame; 36. a screw rod; 37. a foot pedal base; 38. a sleeve base; 4. a seat frame.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:

the utility model relates to a rope-driven lower limb joint rehabilitation mechanism arranged on a wheelchair seat, which comprises a main body part, a pedal mechanism and a rope driving device,

the upper end of the main body part is connected and fixed on the seat frame 4 by two joint bases 110, and the lower end is connected with the pedal mechanism; the main body part comprises a joint base 110, three rigidity-changing structures, a first joint 109, a guide rod 104, a linear push rod 106, a second joint 108, a third joint 112, a support frame 111 and a linear push rod base 107, wherein the linear push rod 106 is fixed on the linear push rod base 107 along the vertical direction, and the guide rod 104 is connected with a sleeve base 38 of the pedal plate mechanism to ensure that the linear push rod can only move along the axial direction without radial force; the two side surfaces of the upper end of the linear push rod base 107 are respectively connected with joint driving ends of a second joint 108 and a second variable stiffness structure 113, the other end of the second joint 108 is connected with a joint driving end of a third variable stiffness structure 114, a joint input end of the third variable stiffness structure 114 is connected with a first joint 109, the upper part of the first joint 109 is connected with a joint base 110 through a pin shaft, the joint input end of the third variable stiffness structure 114 transmits power with a third motor 105 through a bevel gear set, the third motor 105 is fixed on the lower part of the first joint, and the third motor is located at the position of the third joint

Medial to the first joint;

the second joint 108 and the third joint 112 are connected through a support frame 111, the second joint and the third joint limit axial movement through the support frame, and the support frame 111 simultaneously connects the second joint and a motor base of a second variable stiffness structure 113 together;

the other end of the third joint 112 is connected to the joint input end of the first variable stiffness structure, and the joint input end of the first variable stiffness structure 102 is connected to the joint drive end of the second variable stiffness structure 113 through the third joint 112; the joint driving end of the second variable stiffness structure 113 transmits power with the second motor 103 through a corresponding bevel gear set; the joint driving end of the first variable stiffness structure is in power transmission with a first motor 101 through a corresponding bevel gear set, and a motor base of the first motor 101 is connected with a joint base 110 fixed on the seat frame 4;

the pedal mechanism comprises a gear 30, a pedal motor 31, a gear shaft 32, pedals 33, an angle limit switch 34, two pedal connecting frames 35, a screw rod 36, a pedal base 37 and a sleeve base 38; the output end of the pedal motor 31 is connected with a gear shaft 32 through a gear set, the gear shaft 32 is fixed on a pedal connecting frame 35, the upper parts of the two pedal connecting frames are symmetrically arranged at two sides of a screw rod 36, the lower end of the pedal connecting frame is fixed on the bottom surface of a pedal 33, and an angle limit switch 34 is arranged on one side of the pedal connecting frame 35 and used for controlling the swinging angle of the pedal; the upper part of the pedal connecting frame is fixed with the pedal base 37 at the same time, a sleeve base 38 is arranged on the pedal base 37 and is used for supporting and fixing the guide rod 104;

the pedal motor 31 drives the pedal connecting frame 35 to rotate through gear group transmission, and the pedal connecting frame 35 rotates around the gear shaft 32 to drive the pedal 33 to swing up and down; the angle limit switch 34 is triggered by the downward swing of the pedal 33 to a certain angle, and the rotation of the pedal motor 31 is cut off;

the rope driving device is provided with three groups of independent driving mechanisms which are connected in parallel, each driving mechanism is connected in the same way, each driving mechanism comprises a rope driving motor 21, a winding drum 22, a pulley block and a rope 25, the pulley block comprises a horizontal pulley 23 and a vertical pulley 24, and the horizontal pulley 23 and the vertical pulley 24 are orthogonally distributed at the bottom of the front end of the seat frame; one end of the rope 25 is fixed with the corresponding joint of the main body part, and the other end is wound on the winding drum 22; the drum 22 is fixed to an output shaft of the rope drive motor 21.

The lower limb joint of the utility model mainly comprises an ankle joint, a knee joint and a hip joint. The mechanism can be used for carrying out rehabilitation training on one joint and carrying out coordination training on a plurality of joints.

The upper end of the first joint 109 is connected with the joint base 110 through a pin shaft, and the lower end is connected with the third variable stiffness structure 114; due to the coupling of the first joint 109, the second joint 108 and the third joint 112 in motion, this method is obviously inefficient if power is applied in sequence during control, so a variable stiffness structure is introduced for decoupling. The utility model discloses well three structure of becoming rigidity structure is the same, and the limiting condition is: due to the overall space limitation of the rehabilitation mechanism and the requirement for the use function of the rehabilitation mechanism, three sets of rigidity-variable structures act on three movable rod pieces (namely three joints) simultaneously.

The variable stiffness structure (see fig. 7) comprises a central shaft, a torsion spring, a first group of steel balls, a first conical disc, a first disc spring, a first sliding block, a second disc spring, a second conical disc, a second group of steel balls, a left end cover, a first pressure spring, a right-handed nut, a left-handed nut, a sleeve, a second pressure spring, a first shaft sleeve and a second shaft sleeve; the two ends of the central shaft are respectively connected with a joint input end and a joint drive end, and the joint input end is connected with a corresponding motor and is fixed through a corresponding motor mounting seat; the helical gear wheel is matched with the central shaft and is fixed with the input end of the joint; a torsion spring is wound outside the sleeve, one end of the torsion spring is fixed with the input end of the joint, and the other end of the torsion spring is fixed with the drive end of the joint; the helical gear big gear is meshed with the helical gear small gear and is connected with a corresponding motor through the helical gear small gear;

the first conical disc, the first sliding block, the first disc spring and the first pressure spring are respectively the same as the corresponding second conical disc, the second sliding block, the second disc spring and the second pressure spring in shape and structure;

the middle part of the central shaft 1024 is provided with a central shaft shoulder 10241, shaft sections at two ends of the central shaft shoulder are provided with lead screws 10242, the rotating directions of the two lead screws are opposite, and the outer sides of the lead screws are provided with first optical axes 10243; a second optical axis 10244 is arranged outside the first optical axis, and a key groove 10245 is arranged on the second optical axis on one side; the outer side of the second optical axis is a third optical axis 10246, the outer side of the third optical axis is a threaded shaft 10247, and shaft shoulders are arranged between every two first optical axis, the second optical axis, the third optical axis and the threaded shaft;

a left end cover 1031, a second pressure spring 1036, a second conical disc 1029, a second disc spring 1028, a left-handed nut 1034, a right-handed nut 1033, a first disc spring 1023, a first conical disc 1021, a first pressure spring 1032 and a helical gear wheel 1039 are sequentially nested on the central shaft 1024 from the driving end to the joint input end, the left-handed nut 1034 and the right-handed nut 1033 are connected to corresponding lead screws of the central shaft 1024 through threads, and the second conical disc 1029 and the first conical disc 1021 are respectively fixed on a first optical axis of the central shaft 1024; the helical gear is arranged on a second optical axis of the central shaft 1024 outside the first conical disc through a key groove 10245, and the left end cover 1031 is arranged on the second optical axis of the central shaft outside the second conical disc; gaps are reserved between the first disc spring 1023, the first compression spring 1032, the second disc spring 1028 and the second compression spring 1036 and the central shaft 1024; the left end cover 1031 is mounted on the second optical axis 10244 of the central shaft 1024 by interference fit and axially positioned by the second shaft sleeve 1038;

the sleeve 1035 is sleeved on the first group of steel balls 1040 and the second group of steel balls 1041, the two ends of the sleeve are distributed with the same number of sliding chutes which are staggered, the number of the sliding chutes can be 3, 4, 5, 6 and the like, and the circumferential side surface of the sleeve is provided with a through groove 10351; the first group of steel balls 1040 are positioned in the steel ball grooves of the first conical disc 1021, and the axial displacement of the first group of steel balls is limited by the flange extending out of the left end cover 1031; the second group of steel balls 1041 is positioned in a steel ball groove of the second cone disc 1029, and the axial displacement of the second group of steel balls is limited by the helical gear wheel 1039;

the first sliding block 1026 is sleeved on the right-handed nut 1033 to limit the rotation of the right-handed nut, and meanwhile, the outer sides of the left and right-handed nuts are distributed with the same number of convex shapes, the convex shapes are matched with the sliding grooves on the sleeve, and the protrusions can slide left and right in the sliding grooves; the second slider 1027 is fitted over the left-hand nut 1034 to limit its rotation.

The rigidity adjusting method of the variable rigidity structure comprises the following steps: the motors (a first motor, a second motor and a third motor) drive a central shaft to rotate through gears, and left-handed and right-handed nuts on the central shaft respectively move towards two ends along the axial direction, so that steel balls on a first conical disc and a second conical disc move in a steel ball groove and then contact with a sleeve, the torsion of a torsion spring is further hindered, the rigidity is changed by adjusting the compression amount of the two disc springs, and the active rigidity changing function is realized; when relative rotation is carried out, the torsion spring is twisted, the inner diameter of the torsion spring is radially deformed, the sleeve is extruded and deformed, so that the first group of steel balls and the first conical disc as well as the second group of steel balls and the second conical disc are mutually matched in pairs, radial displacement is converted into axial displacement, the first disc spring and the second disc spring are compressed, relative rotation of the joint driving end and the joint input end is blocked, flexible output is realized, and the passive rigidity changing function is realized.

The utility model discloses install in the operating principle and the working process of the recovered mechanism of rope drive low limbs joint of wheelchair seat are:

the rehabilitation process of the joint is carried out by utilizing the rehabilitation mechanism: according to the motion trail of the pedal plate when the lower limb joint of the human body is recovered, the rotating positions of the first joint 109, the second joint 108 and the third joint 112, the pushing distance of the linear push rod 106 and the swinging angle of the pedal plate 33 are reversely deduced. The rotation position of the joint can drive the winding drum 22 to rotate clockwise or anticlockwise through the rope driving motor 21, and the rope 25 with one end fixed on the winding drum 22 moves around the horizontal pulley 23 and the vertical pulley 24 to pull the rotation of the joint. The pedal mechanism provides torque through the pedal motor 31 to drive the gear 30 to rotate, the gear shaft 32 is fixed with the pedal connecting frame 35, the pedal 33 can swing up and down around the screw rod 36, and when the pedal 33 swings down to the limit position, the angle limit switch 34 is triggered, and the pedal motor 31 stops rotating.

The rehabilitation mechanism is provided with a control system, so that the independent rehabilitation training of hip joints, knee joints and ankle joints can be realized, a rehabilitee only needs to sit on a wheelchair, feet are placed on a pedal plate, the pedal plate is used as a platform, the independent training or the coordinated training of the hip joints, the knee joints and the ankle joints can be realized through the motion trail of the human feet planned in advance, the comfort and the safety are high, the mobility of the lower limb joints of the human body can also reduce the impact injury even if the control fails, and the mechanism is installed on a wheelchair seat due to the light weight of rope driving, so that the load-dead weight ratio of the whole machine can be improved.

Example 1

The rope-driven lower limb joint rehabilitation mechanism installed on the wheelchair seat comprises a main body part 1, a pedal mechanism 3 and a rope driving device 2,

the upper end of the main body part is connected and fixed on the seat frame 4 by two joint bases 110, and the lower end is connected with the pedal mechanism; the main body part comprises a joint base 110, three variable stiffness structures, a first joint 109, a guide rod 104, a linear push rod 106, a second joint 108, a third joint 112, a support frame 111 and a linear push rod base 107,

the third variable stiffness structure 114 is driven by the third motor 105 at the inner side through a gear set to rotate a central shaft 1024, an inner nut axially moves to extrude a disc spring, and an axial force is converted into a radial force by utilizing a ball and a conical disc, so that variable stiffness is realized. One end of the second joint 108 is connected to the third stiffness varying structure 114, and the other end is connected to the linear push rod base 106. The tail end of the linear push rod is connected with a pedal base 37. The outer side of the third joint 112 is connected with the first variable stiffness structure 102, the first motor base is fixed on the wheelchair frame, and the second joint 108 and the third joint 112 limit axial movement through the support frame 111.

The pedal mechanism comprises a gear 30, a pedal motor 31, a gear shaft 32, a pedal 33, an angle limit switch 34, a pedal connecting frame 35, a screw rod 36, a pedal base 37 and a sleeve base 38. The pedal connecting frame 35 is symmetrically arranged at two sides of the screw rod 36, and the other end is fixed on the bottom surface of the pedal 33. The pedal motor 31 is fixed at one end of the base, and drives the pedal connecting frame 35 to rotate through gear transmission, and the pedal connecting frame 35 rotates around the screw rod 36 to drive the pedal 33 to swing up and down. The angle limit switch 34 is triggered by the foot pedal 33 swinging down to a limit angle, and the rotation of the foot pedal motor 31 is cut off.

The rope driving device is composed of three groups of mechanisms connected in parallel, and comprises a rope driving motor 21, a winding drum 22, a horizontal pulley 23, a vertical pulley 24 and a rope 25. The rope drive comprises three independent sets of mechanisms, each set of ropes being connected in the same manner. The cable 25 is fixed at one end to the knuckle of the body portion and at the other end wound around the drum 22.

Taking a recovered knee joint as an example, when the angle of the human knee joint changes from 95 ° in fig. 5 to 130 ° in fig. 6, the rope driving motor 21 drives the winding drum 22 to rotate, so that the rope 25 moves around the horizontal pulley 23 and the vertical pulley 24, the first joint 109 rotates counterclockwise around the top pin under the traction of the rope 25, the second joint 108 rotates clockwise around the central axis of the third variable stiffness structure 114, and the linear push rod 106 rotates counterclockwise around the top pin, wherein the action condition of the third variable stiffness structure 114 is that the third motor 105 drives the central axis 1024 thereof to rotate through a gear set, the inner nut moves to the axial central position to release the pressure of the disc spring, the first set of steel balls 1040 and the second set of steel balls 1041 move to the middle along the sliding groove, and the diameter of the sleeve 1035 decreases, thereby reducing the extrusion of the torsion spring 1022. The pedal motor 31 rotates the gear 30, so that the pedal 33 instantaneously rotates around the gear shaft 32.

The foundation the utility model discloses the modification and the equal transform of doing still belong to the utility model discloses a protection scope.

The utility model discloses the nothing is mentioned the part and is applicable to prior art.

Claims (5)

1. The utility model provides an install in recovered mechanism of rope drive low limbs joint of wheelchair seat, includes main part, pedal mechanism, rope drive arrangement and seat frame, it is fixed with the corresponding joint of main part that rope drive arrangement is fixed which characterized in that:

the upper end of the main body part is connected and fixed on the seat frame by two joint bases, and the lower end of the main body part is connected with the pedal mechanism; the main body part comprises a joint base, three variable stiffness structures, a first joint, a guide rod, a linear push rod, a second joint, a third joint, a support frame and a linear push rod base, wherein the linear push rod is fixed on the linear push rod base along the vertical direction, and the guide rod is connected with the pedal mechanism; the two side surfaces of the upper end of the linear push rod base are respectively connected with a second joint and a joint driving end of a second variable stiffness structure, the other end of the second joint is connected with a joint driving end of a third variable stiffness structure, a joint input end of the third variable stiffness structure is connected with a first joint, the upper part of the first joint is connected with one joint base through a pin shaft, a joint input end of the third variable stiffness structure transmits power with a third motor through a bevel gear set, and the third motor is fixed at the lower part of the first joint;

the second joint and the third joint limit axial movement through a support frame, and the support frame simultaneously connects the second joint and a motor base of the second variable stiffness structure together;

the other end of the third joint is connected to the joint input end of the first variable stiffness structure, and the joint input end of the first variable stiffness structure is connected with the joint drive end of the second variable stiffness structure through the third joint; the joint driving end of the second variable stiffness structure transmits power with a second motor through a corresponding bevel gear set; the joint driving end of the first variable stiffness structure is in power transmission with a first motor through a corresponding bevel gear set, and a motor base of the first motor is connected with a joint base fixed on the seat frame;

the pedal mechanism comprises a gear, a pedal motor, a gear shaft, pedals, an angle limit switch, two pedal connecting frames, a screw rod, a pedal base and a sleeve base; the output end of the pedal motor is connected with a gear shaft through a gear set, the gear shaft is fixed on a pedal connecting frame, the upper parts of the two pedal connecting frames are symmetrically arranged on two sides of a screw rod, the lower end of the pedal connecting frame is fixed on the bottom surface of a pedal, and an angle limit switch is arranged on one side of the pedal connecting frame; the upper part of the pedal connecting frame is fixed with the pedal base, and the pedal base is provided with a sleeve base for supporting and fixing the guide rod.

2. The rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat as claimed in claim 1, wherein the three variable stiffness structures are the same, and each variable stiffness structure comprises a central shaft, a torsion spring, a first group of steel balls, a first conical disc, a first disc spring, a first slider, a second disc spring, a second conical disc, a second group of steel balls, a left end cover, a first compression spring, a right-handed nut, a left-handed nut, a sleeve, a second compression spring, a first shaft sleeve and a second shaft sleeve; the two ends of the central shaft are respectively connected with a joint, a joint input end and a joint drive end, and the joint input end is connected with a corresponding motor and fixed through a corresponding motor mounting seat; the helical gear wheel is matched with the central shaft and is fixed with the joint input end; a torsion spring is wound outside the sleeve, one end of the torsion spring is fixed with the joint input end, and the other end of the torsion spring is fixed with the joint driving end; the helical gear big gear is meshed with the helical gear small gear and is connected with a corresponding motor through the helical gear small gear;

the first conical disc, the first sliding block, the first disc spring and the first pressure spring are respectively the same as the corresponding second conical disc, the second sliding block, the second disc spring and the second pressure spring in shape and structure.

3. The rope-driven lower limb joint rehabilitation mechanism mounted on a wheelchair seat as claimed in claim 2, wherein the central shaft is a central shoulder, the shaft sections at the two ends of the central shoulder are lead screws, the rotation directions of the two lead screws are opposite, and the outer side of each lead screw is a first optical axis; the outer side of the first optical axis is provided with a second optical axis, and a key groove is formed in the second optical axis on one side; the outer side of the second optical axis is a third optical axis, the outer side of the third optical axis is a threaded shaft, and shaft shoulders are arranged between every two first optical axis, the second optical axis, the third optical axis and the threaded shaft;

a left end cover, a second pressure spring, a second conical disc, a second disc spring, a left-handed nut, a right-handed nut, a first disc spring, a first conical disc, a first pressure spring and a helical gear wheel are sequentially nested on the central shaft from the driving end to the joint input end, the left-handed nut and the right-handed nut are connected to corresponding lead screws of the central shaft through threads, and the second conical disc and the first conical disc are respectively fixed on a first optical axis of the central shaft; the helical gear big gear is arranged on a second optical axis of the central shaft on the outer side of the first conical disc through a key groove, and the left end cover is positioned on the second optical axis of the central shaft on the outer side of the second conical disc; gaps are reserved between the first disc spring, the first pressure spring, the second disc spring and the second pressure spring and the central shaft; the left end cover is arranged on a second optical axis of the central shaft in an interference fit mode and is axially positioned through a second shaft sleeve;

the sleeve is sleeved on the first group of steel balls and the second group of steel balls, a plurality of sliding grooves are uniformly distributed on the circumferences of the left end and the right end, and a through groove is formed in the circumferential side surface of the sleeve; the first group of steel balls are positioned in the steel ball grooves of the first conical disc, and the axial displacement of the first group of steel balls is limited by the flange extending out of the left end cover; the second group of steel balls are positioned in the steel ball grooves of the second conical plate, and the axial displacement of the second group of steel balls is limited by the helical gear bull gear;

the first sliding block is sleeved on the right-handed nut to limit the rotation of the right-handed nut, the outer side surface of the sliding block is uniformly provided with bulges with the same number as the second sliding block along the axial direction of the sliding block, the shapes of the bulges are matched with the sliding groove on the sleeve, and the bulges can slide left and right in the sliding groove; the second sliding block is sleeved on the left-handed nut to limit the rotation of the left-handed nut.

4. The cord-driven lower limb joint rehabilitation mechanism mounted to a wheelchair seat as claimed in claim 1, wherein three variable stiffness structures are arranged in the main body portion of the mechanism, the first variable stiffness structure being connected to the joint base at one end and fixed to the seat frame at the other end; one end of the second variable-stiffness structure is connected with the support frame, and the other end of the second variable-stiffness structure is connected with the linear push rod base; the third variable stiffness structure is disposed intermediate the first joint and the second joint.

5. The wheelchair-mounted rope-driven lower limb joint rehabilitation apparatus of claim 1, wherein the rope driving device has three sets of independent driving mechanisms connected in parallel, each driving mechanism is connected in the same manner, each driving mechanism comprises a rope driving motor, a winding drum, a pulley block and a rope, and the pulley block comprises a horizontal pulley and a vertical pulley, which are orthogonally distributed at the bottom of the front end of the seat frame.

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