A cable-driven lower limb rehabilitation robot based on a multi-level adjustable variable stiffness device

Abstract

The present invention relates to a flexible cable-driven lower limb rehabilitation robot based on a multi-stage adjustable variable stiffness device. It comprises a left leg exoskeleton and a right leg exoskeleton arranged on both sides of a control platform, wherein the left leg exoskeleton and the right leg exoskeleton respectively comprise a tibial rod, wherein the lower end of the tibial rod is connected to a foot support plate via an ankle joint, and the upper end of the tibial rod is connected to a support arm via a knee joint; an ankle joint variable stiffness device is connected to the ankle joint, a knee joint variable stiffness device is connected to the knee joint, the ankle joint variable stiffness device is connected to an ankle joint driving device, and the knee joint variable stiffness device is connected to a knee joint driving device. As can be seen from the above technical solution, the present invention can adjust the strength and stiffness of the driving force at different rehabilitation stages according to the specific needs of the patient by introducing a variable stiffness device, thereby achieving more refined rehabilitation training. Moreover, the variable stiffness devices of each joint are adjusted independently without affecting each other. The use of flexible cable drive has better safety, flexibility and comfort.

Description

Technical Field

[0001] The present invention relates to the field of rehabilitation robots, and in particular to a flexible cable-driven lower limb rehabilitation robot based on a multi-stage adjustable variable stiffness device. Background Art

[0002] In the field of rehabilitation medicine, with the advent of an aging society, the demand for rehabilitation treatment continues to increase, especially for patients with neurological diseases such as stroke and spinal cord injury. Traditional rehabilitation treatment methods rely primarily on manual guidance from physical therapists. However, due to issues such as long treatment times, limited therapeutic effects, and significant individual patient variability, more intelligent and automated rehabilitation equipment is urgently needed.

[0003] Current rehabilitation robots have deficiencies in human-machine interaction, compliance, and adaptability. For example, some ankle rehabilitation robots have poor human-machine structure matching, poor compliance, and weak adaptability, which limits their application in rehabilitation training. In order to solve the above problems, a device that can adjust stiffness is needed to adapt to the rehabilitation needs of different patients. Such a device should have a simple and compact structure and high stiffness-tension linear characteristics to improve the range and accuracy of variable stiffness control. As a new type of flexible drive method, flexible cable drive can provide highly compliant control and can simulate the natural movement trajectory of human joints. Traditional flexible drive systems mostly rely on fixed stiffness control, which is difficult to accurately adjust according to the rehabilitation progress and needs of different patients. Therefore, they have poor adaptability in personalized rehabilitation treatment.

[0004] At present, the research and application of lower limb rehabilitation robots have been very extensive, but there are still some shortcomings waiting to be improved. Patent CN112426327B discloses a variable stiffness cable-driven actuator based on a nonlinear mechanism. This patent uses a motor-driven mechanical action to change the stiffness, which increases the overall weight of the mechanism and increases the burden on the patient's upper body. The response to the safe position cannot be timely, and there are certain safety hazards. Patent CN108606907A proposes a movable parallel cable-driven lower limb rehabilitation robot that can realize gait training and walking training in passive, assisted and active modes. However, the overall structure is huge, which increases the cost of the machine and has certain requirements for the application scenario. Although safety harnesses and tension sensors are mentioned, emergency situations that may occur during patient use are not considered. Emergency response measures are insufficient, and patients are pulled by safety harnesses, making rehabilitation comfort low. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned drawbacks and provide a flexible cable-driven lower limb rehabilitation robot based on a multi-stage adjustable variable stiffness device.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: comprising a left leg exoskeleton and a right leg exoskeleton symmetrically arranged on both sides of a control platform, wherein the left leg exoskeleton and the right leg exoskeleton each include a tibial rod, the lower end of the tibial rod being connected to a foot support plate via an ankle joint, and the upper end of the tibial rod being connected to a support arm fixed to the control platform via a knee joint;

[0007] The ankle joint is connected to an ankle joint stiffness changing device, and the knee joint is connected to a knee joint stiffness changing device. The ankle joint stiffness changing device and the knee joint stiffness changing device have the same structure and each include a shell, end caps and a winding ring are fixed to both ends of the shell, a stiffness changing shaft is provided in the shell, one end of the stiffness changing shaft close to the end cap is cantilevered outside the shell and is fixedly connected to the electromagnetic brake, and one end of the stiffness changing shaft close to the winding ring is fixedly connected to the ankle joint rotation shaft or the knee joint rotation shaft through a coupling;

[0008] The variable stiffness rotating shaft is provided with a first magnetic transmission plate, an elastic element group, a second magnetic transmission plate and an electromagnet in sequence from the end cover to the winding ring, the first magnetic transmission plate, the elastic element group and the second magnetic transmission plate are connected to form a whole by a connecting rod, one end of the connecting rod near the end cover is connected to the end cover by a compression spring, the elastic element group is composed of a plurality of disc springs with the same structure and different elasticities, the variable stiffness rotating shaft is provided with a key fixed to the elastic element group, the circumference of the first magnetic transmission plate and the second magnetic transmission plate are respectively provided with a slider, the slider is matched with a slide groove provided on the inner wall of the shell, the slide groove is arranged along the axial direction of the shell, when the electromagnet is energized, the second magnetic transmission plate is attracted to move in the direction of the electromagnet, thereby driving the elastic element group to slide along the direction defined by the slide groove, and the connection and fixation of each disc spring in the elastic element group to the key is achieved by controlling the current size of the electromagnet, and when the electromagnet is de-energized, the elastic element group is driven to return to its position by the compression spring;

[0009] The winding ring in the ankle joint stiffness changing device is connected to the ankle joint driving device through a first flexible cable, and the winding ring in the knee joint stiffness changing device is connected to the knee joint driving device through a second flexible cable. The ankle joint driving device and the knee joint driving device have the same structure and both include a reel connected to the first flexible cable or the second flexible cable. The reel is driven to rotate by a reel motor to realize the retraction and extension of the corresponding flexible cable.

[0010] The elastic element group includes a first elastic element group consisting of a first disc spring, a second disc spring, and a third disc spring, and a second elastic element group consisting of a fourth disc spring and a fifth disc spring. The key includes a first key that cooperates with the first elastic element group and a second key that cooperates with the second elastic element group. A limiting sleeve is fixed on the connecting rod between the first elastic element group and the second elastic element group. Gaskets are respectively fixed on the connecting rods between the disc springs of the first elastic element group, between the first elastic element group and the first magnetic transmission plate, between the disc springs of the second elastic element group, and between the second elastic element group and the second magnetic transmission plate.

[0011] The ankle joint includes an ankle joint rotation axis and an ankle joint support frame, the lower end of the tibial rod is fixedly connected to the first ear seat of the ankle joint support frame, the two ends of the ankle joint rotation axis are respectively rotatably connected to the second ear seat of the ankle joint support frame through deep groove ball bearings, a first connecting bracket is coaxially fixed to the ankle joint rotation axis, and the first connecting bracket is fixed to the second connecting bracket on the sole support plate;

[0012] The knee joint includes a knee joint rotation axis and a knee joint support frame. The third ear seat of the knee joint support frame is fixed to the support arm. The two ends of the knee joint rotation axis are respectively rotatably connected to the fourth ear seat of the knee joint support frame through deep groove ball bearings. A third connecting bracket is coaxially fixed on the knee joint rotation axis, and the third connecting bracket is fixedly connected to the upper end of the tibial rod.

[0013] The tibial rod is a split structure, including an upper tibial rod and a lower tibial rod that are plug-fitted together. The upper tibial rod and the lower tibial rod are both integrally formed structures. The upper tibial rod includes a first rod body connected to the knee joint and a second rod body inserted into the lower tibial rod. The lower tibial rod includes a third rod body plug-fitted with the second rod body and a fourth rod body connected to the ankle joint. The cross-sections of the first rod body, the second rod body, the third rod body and the fourth rod body are all square, and the third rod body is a structure with an open top, a hollow interior, a closed bottom end and hollow front and rear end faces. A fixing frame is provided near the upper end of the lower tibial rod. The fixing frame is fixedly connected to the lower tibial rod, and a strap for fixing the leg is provided on the fixing frame.

[0014] The cam is fixed to the chassis and the cam is fixed to the chassis, and the cam is fixed to the chassis with a first end fixed to the chassis, and a second end fixed to the chassis is fixed to the chassis with a second end fixed to the chassis.

[0015] A spring is provided between the lower tibial rod and the first connecting bracket to provide movement buffer for the ankle joint. Two springs are provided, and the two springs are symmetrically arranged on the front and back sides of the lower tibial rod. The upper end of the spring is fixed to the upper spring seat connected to the lower tibial rod, and the lower end of the spring is fixed to the lower spring seat on the first connecting bracket.

[0016] The knee joint is provided with a limit device for limiting the rotation angle of the knee joint, and the limit device includes a first limit plate and a second limit plate symmetrically arranged on both sides of the third connecting bracket, the upper ends of the first limit plate and the second limit plate are sleeved on the knee joint rotation axis, and the lower ends of the first limit plate and the second limit plate are fixed to the left and right side surfaces of the upper tibial rod, and the limit device also includes a limit block fixed to the knee joint support frame, and the first limit plate and the second limit plate are provided with a limit surface that cooperates with the limit block.

[0017] The output shaft of the drum motor is connected to the drum shaft through a plum blossom coupling, and the two ends of the drum shaft are respectively connected to the first bearing bracket and the second bearing bracket through deep groove ball bearings. The drum motor is fixed on the motor bracket, and a trapezoidal screw is also provided between the first bearing bracket and the second bearing bracket, and the two ends of the trapezoidal screw are respectively rotatably connected to the first bearing bracket and the second bearing bracket. The trapezoidal screw is provided with a second nut seat that forms a screw nut movement with it, and a first reversing wheel is fixed on the second nut seat, and a second reversing wheel is fixed on the first bearing bracket. The first reversing wheel is parallel to the axle of the second reversing wheel, and the axle of the first reversing wheel is perpendicular to the drum shaft. A guide rod is provided between the first bearing bracket, the second bearing bracket and the second nut seat, and a three-pulley tension sensor is also provided on the side of the drum.

[0018] A pulley transmission device connecting the drum and the trapezoidal screw is provided between the two. The pulley transmission device includes a first pulley coaxially arranged with the drum, a second pulley coaxially arranged with the trapezoidal screw, and a belt connecting the first pulley and the second pulley. A tensioning pulley is provided below the belt.

[0019] One end of the first flexible cable is fixedly connected to the drum in the ankle joint driving device, and the other end of the first flexible cable is sequentially wound around the first reversing wheel, the second reversing wheel, the three-pulley tension sensor, and the first pulley group, and then fixed to the winding ring in the ankle joint variable stiffness device; one end of the second flexible cable is fixedly connected to the drum in the knee joint driving device, and the other end of the second flexible cable is sequentially wound around the first reversing wheel, the second reversing wheel, the three-pulley tension sensor, and the second pulley group, and then fixed to the winding ring in the knee joint variable stiffness device;

[0020] The first pulley group includes a first pulley, a second pulley, a first pulley block, a third pulley, a fourth pulley, a fifth pulley, a sixth pulley and a seventh pulley arranged in sequence; the second pulley group includes an eighth pulley, a second pulley block, a ninth pulley, a tenth pulley, an eleventh pulley, a twelfth pulley and a thirteenth pulley arranged in sequence, wherein: the first pulley is fixed to a first pulley bracket on the side of the second layer plate of the control platform, the second pulley and the eighth pulley are fixed to a second pulley bracket on the side of the first layer plate of the control platform, the third pulley, the fourth pulley, the fifth pulley, the sixth pulley, the seventh pulley, the ninth pulley, the tenth pulley, the eleventh pulley, the twelfth pulley and the thirteenth pulley are all fixed on a pulley support plate, and the pulley support plate, the first pulley block and the second pulley block are all fixed on the bottom plate inside the support arm.

[0021] The beneficial effects of the present invention are:

[0022] 1. The present invention is provided with an ankle joint variable stiffness device and a knee joint variable stiffness device, which can adjust the stiffness of the driver according to the rehabilitation needs of the rehabilitation patient; at the same time, the elastic element in the variable stiffness device adopts a disc spring structure, so that the variable stiffness device has a lower impedance, can provide a larger elastic force in a smaller volume, and has a higher load-bearing capacity. The disc spring deforms evenly when subjected to force, can provide a stable elastic force, and can improve the stability of rehabilitation training.

[0023] 2. The elastic element group of the present invention provides three stiffness gears through five disc springs, which can achieve the selection of multiple stiffness conditions under one installation condition, greatly enhancing the environmental applicability of the variable stiffness device, and realizing that one device meets multiple needs. This modular design can reduce the cost of the equipment.

[0024] 3. In the event of an emergency such as a collision, overload, or cable derailment of the robot, the present invention uses two sets of disc springs in conjunction with electromagnetic brakes to alleviate impact on joints and damage to mechanical structures, thereby improving the safety of rehabilitation training.

[0025] 4. The present invention adopts a flexible cable drive, which makes the robot more flexible, avoids rigid contact between the mechanism and the human body, and improves the safety and comfort of rehabilitation training; during the rehabilitation process, a tension sensor is used to monitor the tension of the flexible cable in real time, further improving the safety of rehabilitation training.

[0026] 5. The ankle joint drive device and knee joint drive device in the present invention are installed on the control platform, which greatly reduces the load on the joints. Combined with the variable stiffness device at the joints, it can realize functions such as driving, braking and stiffness adjustment, thereby increasing the auxiliary torque for patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 It is a structural diagram of the control platform of the present invention.

[0029] Figure 3 It is a schematic diagram of the overall structure of the tibial rod of the present invention.

[0030] Figure 4 yes Figure 3 Schematic diagram of the decomposition structure.

[0031] Figure 5 This is a schematic diagram of the overall structure of the tibial rod and the length adjustment device of the present invention. Figure 1 .

[0032] Figure 6 This is a schematic diagram of the overall structure of the tibial rod and the length adjustment device of the present invention. Figure 2 .

[0033] Figure 7 yes Figure 6 Schematic diagram of the decomposition structure.

[0034] Figure 8 This is a schematic diagram of the structure of the left leg exoskeleton of the present invention. Figure 1 .

[0035] Figure 9 This is a schematic diagram of the structure of the left leg exoskeleton of the present invention. Figure 2 .

[0036] Figure 10 This is a schematic diagram of the overall structure of the ankle joint and the lower tibial rod of the present invention. Figure 1 .

[0037] Figure 11This is a schematic diagram of the overall structure of the ankle joint and the lower tibial rod of the present invention. Figure 2 .

[0038] Figure 12 yes Figure 11 Schematic diagram of the decomposition structure.

[0039] Figure 13 It is a schematic diagram of the connection between the first connecting bracket and the foot support plate of the present invention.

[0040] Figure 14 yes Figure 13 Schematic diagram of the decomposition structure.

[0041] Figure 15 This is a schematic diagram of the structure of the ankle joint of the present invention Figure 1 .

[0042] Figure 16 This is a schematic diagram of the structure of the ankle joint of the present invention Figure 2 .

[0043] Figure 17 It is a schematic diagram of the connection between the knee joint and the upper tibial rod of the present invention.

[0044] Figure 18 yes Figure 17 Schematic diagram of the decomposition structure.

[0045] Figure 19 It is a schematic structural diagram of the knee joint of the present invention.

[0046] Figure 20 It is a schematic structural diagram of the limiting device of the present invention.

[0047] Figure 21 This is a schematic diagram of the structure of the ankle joint stiffness variable device of the present invention. Figure 1 .

[0048] Figure 22 This is a schematic diagram of the structure of the ankle joint stiffness variable device of the present invention. Figure 2 .

[0049] Figure 23 This is a schematic diagram of the decomposition structure of the ankle joint stiffness variable device of the present invention. Figure 1 .

[0050] Figure 24 This is a schematic diagram of the decomposition structure of the ankle joint stiffness variable device of the present invention. Figure 2 .

[0051] Figure 25 It is a structural schematic diagram of the shell of the present invention.

[0052] Figure 26 It is a structural schematic diagram of the first disc spring of the present invention.

[0053] Figure 27 It is a structural schematic diagram of the second layer plate and the ankle joint driving device of the present invention.

[0054] Figure 28 This is a schematic diagram of the structure of the ankle joint drive device of the present invention. Figure 1 .

[0055] Figure 29 This is a schematic diagram of the structure of the ankle joint drive device of the present invention Figure 2 .

[0056] Figure 30 It is a structural schematic diagram of the support arm of the present invention.

[0057] Figure 31 It is a schematic diagram of the connection of the pulleys on the pulley supporting plate of the present invention.

[0058] Figure 32 It is a schematic diagram of the connection of the pulleys on the first pulley bracket and the second pulley bracket of the present invention.

[0059] 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 50, 51, 32, 33, 34, 46, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 67, 68, 69, 70, 71, 72, 73, 74, 75 Spring seat 25, lower spring seat 26, first bearing end cover 27, second bearing end cover 28, sole support plate 3, second connecting bracket 31, knee joint 4, knee joint rotation axis 41, knee joint support frame 42, third ear seat 421, fourth ear seat 422, third connecting bracket 43, first limiting plate 44, second limiting plate 45, limiting block 46, third bearing end cover 47, fourth bearing end cover 48, support arm 5, pulley support plate 51, L-shaped bracket 52, arm body 53, dust cover 54, ankle joint variable stiffness device 6, housing 601, end cover 602, winding ring 603, first wire ring 6031, second wire ring 6032, variable stiffness rotating shaft 604, electromagnetic brake 605, first magnetic transmission plate 606, second magnetic Transmission plate 607, electromagnet 608, connecting rod 609, compression spring 610, slider 611, slide groove 612, first disc spring 613, keyway 6131, second disc spring 614, third disc spring 615, fourth disc spring 616, fifth disc spring 617, first key 618, second key 619, limiting sleeve 620, gasket 621, bracket 622, connecting ring 6221, ankle joint drive device 7, reel 701, reel motor 702, cylindrical shaft 703, first bearing bracket 704, second bearing bracket 705, motor bracket 706, trapezoidal screw 707, second nut seat 708, first reversing wheel 709, second reversing wheel 710, guide rod 711, three-pulley tension sensor Device 712, first pulley 713, second pulley 714, belt 715, tensioner 716, first pulley 801, second pulley 802, first pulley block 803, third pulley 804, fourth pulley 805, fifth pulley 806, sixth pulley 807, seventh pulley 808, eighth pulley 809, second pulley block 810, ninth pulley 811, tenth pulley 812, eleventh pulley 813, twelfth pulley 814, thirteenth pulley 815, first pulley bracket 816, second pulley bracket 817, control platform 10, frame body 101, board surface 102, first layer board 103, second layer board 104, left leg exoskeleton 20, right leg exoskeleton 30, first flexible cable 40, second flexible cable 50. DETAILED DESCRIPTION

[0060] The present invention will be further described below with reference to the accompanying drawings:

[0061] like Figure 1 The shown embodiment shows a flexible cable-driven lower limb rehabilitation robot based on a multi-stage adjustable variable stiffness device, comprising a left leg exoskeleton 20 and a right leg exoskeleton 30 symmetrically arranged on both sides of a control platform 10. The left leg exoskeleton 20 and the right leg exoskeleton 30 each comprise a tibial rod 1, the lower end of the tibial rod 1 being connected to a foot support plate 3 via an ankle joint 2, and the upper end of the tibial rod 1 being connected to a support arm 5 fixed to the control platform 10 via a knee joint 4.

[0062] Further, such as Figure 2 As shown, the control platform 10 includes a square frame body 101 , a board surface 102 for a patient to sit on is provided on the top of the frame body 101 , and a first layer board 103 and a second layer board 104 are fixed in the frame body 101 .

[0063] The left leg exoskeleton 20 and the right leg exoskeleton 30 of the present invention have the same structure. Figure 8 、 Figure 9 As shown, the left leg exoskeleton 20 is taken as an example for description below, and the structure of the right leg exoskeleton 30 is not repeated here.

[0064] Further, such as Figure 3 、 Figure 4 As shown, the tibial rod 1 is a split structure, including an upper tibial rod 11 and a lower tibial rod 12 that form a plug-fitting connection. The upper tibial rod 11 and the lower tibial rod 12 are both integrally formed structures. Specifically, the upper tibial rod 11 includes a first rod body 111 connected to the knee joint 4 and a second rod body 112 inserted into the lower tibial rod 12. The lower tibial rod 12 includes a third rod body 121 plugged into the second rod body 112 and a fourth rod body 122 connected to the ankle joint 2. The cross-sections of the first rod body 111, the second rod body 112, the third rod body 121 and the fourth rod body 122 are all square, and the third rod body 121 is a structure with an open top, a hollow interior, a closed bottom and hollow front and rear end faces. A fixing frame 13 is provided near the upper end of the lower tibial rod 12. The fixing frame 13 is fixedly connected to the lower tibial rod 12. A strap 14 for fixing the leg is provided on the fixing frame 13. The strap 14 is used to fix the patient's leg during the rehabilitation process to improve the safety of rehabilitation.

[0065] Further, such as Figure 5 、 Figure 6 、 Figure 7As shown, the length of the tibial rod 1 is adjustable, and the length adjustment device 15 is used between the upper tibial rod 11 and the lower tibial rod 12 to complete the length adjustment of the tibial rod 1. The length adjustment device 15 includes a ball screw 151 arranged in the vertical direction and a rotating rod 152 arranged in the horizontal direction. The ball screw 151 is arranged in parallel on the rear side of the tibial rod 1. The upper end of the ball screw 151 is provided with a screw support seat 153, and the screw support seat 153 is connected to the fixed frame 13. The lower end of the ball screw 151 is coaxially connected to the first bevel gear 154, and the ball screw 151 is provided with a screw nut formed therewith. The first nut seat 155 is fixed to the upper tibial rod 11; one end of the rotating rod 152 is coaxially connected to the second bevel gear 156, which meshes with the first bevel gear 154. The other end of the rotating rod 152 is fixed to a handle rotating disk 157, and the handle rotating disk 157 is connected to a handle 1571. The middle section of the rotating rod 152 is provided with a rotating rod support seat 158. The rotating rod 152 is fixed in the rotating rod support seat 158 ​​through a rotating rod sleeve 1521. The rotating rod support seat 158 ​​is fixed to the lower tibial rod 12 through a fourth connecting bracket 159. The fourth connecting bracket 159 includes an inverted U-shaped base 1591 fixed to the bottom of the rotating rod support seat 158. The inverted U-shaped base 1591 is fixed to the upper spring seat 25 through a connecting plate 1592.

[0066] The adjustment principle of the length adjustment device 15 is as follows: when the length of the tibial rod 1 needs to be adjusted, the handle turntable 157 is rotated through the handle 1571, thereby driving the ball screw 151 to rotate through the transmission of the second bevel gear 156 and the first bevel gear 154, and the first nut seat 155 on the ball screw 151 drives the upper tibial rod 11 fixed thereto to move relative to the lower tibial rod 12, thereby completing the adjustment of the length of the tibial rod 1.

[0067] Further, such as Figure 15 、 Figure 16 As shown, the ankle joint 2 includes an ankle joint rotation axis 21 and an ankle joint support frame 22. The lower end of the tibial rod 1 is fixedly connected to the first ear seat 221 of the ankle joint support frame 22. The two ends of the ankle joint rotation axis 21 are respectively rotatably connected to the second ear seat 222 of the ankle joint support frame 22 through deep groove ball bearings. The outer side surfaces of the second ear seat 222 are respectively fixed with the first bearing end cover 27 and the second bearing end cover 28. A first connecting bracket 23 is coaxially fixed to the ankle joint rotation axis 21. The first connecting bracket 23 is fixed to the second connecting bracket 31 on the sole support plate 3. Specifically, the first connecting bracket 23 is fixedly connected to the ankle joint rotation axis 21 through a key and rotates synchronously with the ankle joint rotation axis 21, as shown in FIG. Figure 13 、 Figure 14As shown, the lower part of the first connecting bracket 23 is fixed to the second connecting bracket 31, and the second connecting bracket 31 is fixed to the transition plate extending from the side of the sole support plate 3 by screws. Preferably, a sole rubber plate 32 is bonded to the sole support plate 3 to provide cushioning for the patient's foot.

[0068] Further, such as Figure 10 、 Figure 11 、 Figure 12 As shown, a spring 24 is provided between the lower tibial rod 12 and the first connecting bracket 23. The spring 24 provides a motion buffer for the ankle joint 2 and reduces the impact on the joint. Two springs 24 are provided, and the two springs 24 are symmetrically arranged on the front and back sides of the lower tibial rod 12. The upper end of the spring 24 is fixed to an upper spring seat 25 connected to the lower tibial rod 12, and the lower end of the spring 24 is fixed to a lower spring seat 26 on the first connecting bracket 23. Specifically, the upper spring seat 25 is a square frame structure. The upper spring seat 25 is sleeved on the lower tibial rod 12 and fixed to the lower tibial rod 12 by screws. The front and back sides of the upper spring seat 25 are respectively provided with ear seats that match the spring 24. The lower spring seat 26 is integrally formed with the first connecting bracket 23, which is equivalent to extending an ear seat on the front and back sides of the first connecting bracket 23 for fixing the spring 24. The two ends of the spring 24 are respectively fixed to the connecting shaft in the corresponding ear seat.

[0069] Further, such as Figure 17 、 Figure 18 、 Figure 19 As shown, the knee joint 4 includes a knee joint rotation axis 41 and a knee joint support frame 42. The third ear seat 421 of the knee joint support frame 42 is fixed to the support arm 5. The two ends of the knee joint rotation axis 41 are rotatably connected to the fourth ear seat 422 of the knee joint support frame 42 via deep groove ball bearings. The outer side surfaces of the fourth ear seat 422 are respectively fixed with a third bearing end cap 47 and a fourth bearing end cap 48. A third connecting bracket 43 is coaxially fixed to the knee joint rotation axis 41. The third connecting bracket 43 is fixed to the upper end of the tibial rod 1. Specifically, the third connecting bracket 43 is fixed to the knee joint rotation axis 41 via a key and rotates synchronously with the knee joint rotation axis 41. The lower end of the third connecting bracket 43 is fixed to the upper tibial rod 11.

[0070] Further, such as Figure 20As shown, the knee joint 4 is provided with a limiting device for limiting the rotation angle of the knee joint 4. The limiting device includes a first limiting plate 44 and a second limiting plate 45 symmetrically arranged on either side of the third connecting bracket 43. The upper ends of the first limiting plate 44 and the second limiting plate 45 are sleeved on the knee joint rotation axis 41, and the lower ends of the first limiting plate 44 and the second limiting plate 45 are fixed to the left and right side surfaces of the upper tibial rod 11. The limiting device also includes a limiting block 46 fixed to the knee joint support frame 42. The first limiting plate 44 and the second limiting plate 45 are provided with limiting surfaces that cooperate with the limiting blocks 46. When the knee joint rotation axis 41 rotates, the upper tibial rod 11 rotates synchronously, and the first limiting plate 44 and the second limiting plate 45 fixed to the upper tibial rod 11 also rotate accordingly. When the limiting surfaces of the first limiting plate 44 and the second limiting plate 45 rotate to contact the limiting blocks 46, the knee joint rotation axis 41 will no longer rotate, thereby safely limiting the movement angle of the knee joint.

[0071] Furthermore, the ankle joint 2 is connected to an ankle joint stiffness varying device 6, and the knee joint 4 is connected to a knee joint stiffness varying device. The ankle joint stiffness varying device 6 and the knee joint stiffness varying device have the same structure. The ankle joint stiffness varying device 6 is used as an example for explanation below, and the knee joint stiffness varying device will not be repeated.

[0072] Specifically, such as Figure 21 、 Figure 22 、 Figure 23 、 Figure 24 As shown, the ankle joint variable stiffness device 6 includes a shell 601, and the two ends of the shell 601 are respectively fixed with end covers 602 and a winding ring 603. A variable stiffness rotating shaft 604 is provided in the shell 601. One end of the variable stiffness rotating shaft 604 close to the end cover 602 is cantilevered outside the shell 601 and is fixedly connected to the electromagnetic brake 605. The end of the variable stiffness rotating shaft 604 close to the winding ring 603 is fixedly connected to the ankle joint rotation axis 21 through a coupling. A first magnetic transmission plate 606, an elastic element group, a second magnetic transmission plate 607 and an electromagnet 608 are sequentially provided on the variable stiffness rotating shaft 604 from the end cover 602 to the winding ring 603. The first magnetic transmission plate 606, the elastic element group and the second magnetic transmission plate 607 are connected to form a whole through a connecting rod 609. The electromagnet 608 is fixed to the variable stiffness rotating shaft 604 through a key. The end of the connecting rod 609 close to the end cover 602 is connected to the end cover 602 through a compression spring 610. One end of the compression spring 610 is connected to the first spring fixing hole provided at the end of the connecting rod 609, and the other end of the compression spring 610 is connected to the second spring fixing hole provided on the end cover 602.

[0073] The elastic element group is composed of a plurality of disc springs of the same structure but different elasticity. A key fixed to the elastic element group is provided on the variable stiffness shaft 604. The first magnetic transmission plate 606 and the second magnetic transmission plate 607 are respectively provided with sliders 611 in the circumference. The sliders 611 are semi-cylindrical protrusions. The sliders 611 cooperate with the slide grooves 612 provided on the inner wall of the housing 601. Figure 25 As shown, the sliding groove 612 is arranged along the axial direction of the housing 601.

[0074] In this embodiment, four groups of sliders 611, slots 612, connecting rods 609, and compression springs 610 are provided. The winding ring 603 in this embodiment is a split structure, including a first wire ring 6031 fixed to the housing 604 and a second wire ring 6032 fixed to the first wire ring 6031.

[0075] The ankle joint variable stiffness device 6 is fixed to the ankle joint support frame 22 through a bracket 622. Specifically, the bracket 622 is arranged below the shell 601. The bracket 622 is semicircular in shape as a whole. One end of the bracket 622 is fixedly connected to the ankle joint support frame 22, and the other end of the bracket 622 is provided with a connecting ring 6221 that is engaged and fixed with the step surface of the electromagnetic brake 605.

[0076] Preferably, the elastic element groups in this embodiment are provided in two groups, including a first elastic element group consisting of a first disc spring 613, a second disc spring 614, and a third disc spring 615, and a second elastic element group consisting of a fourth disc spring 616 and a fifth disc spring 617. The key includes a first key 618 that cooperates with the first elastic element group and a second key 619 that cooperates with the second elastic element group. Each disc spring in the first elastic element group is provided with a key slot that cooperates with the first key 618 at the same position. The first disc spring 613 has a key slot 6131 on its inner wall that cooperates with the first key 618. Figure 26 As shown. Each disc spring in the second elastic element group is provided with a keyway at the same position that cooperates with the second key 619. The cooperation between the key and the keyway drives the variable stiffness shaft 604 to rotate. A limiting sleeve 620 is fixed to the connecting rod 609 between the first elastic element group and the second elastic element group. Washers 621 are respectively fixed to the connecting rods 609 between the disc springs of the first elastic element group, between the first elastic element group and the first magnetic transmission plate 606, between the disc springs of the second elastic element group, and between the second elastic element group and the second magnetic transmission plate 607.

[0077] During operation, electromagnet 608 is energized, generating varying magnetic forces depending on the current flow, attracting second magnetic drive plate 607 toward electromagnet 608, thereby driving the first and second elastic element groups to slide along the direction defined by slot 612. During this sliding process, the current flowing through electromagnet 608 is controlled to secure the disc springs in each elastic element group to the key. In this embodiment, the disc springs can move in three different positions: in the first position, the third disc spring 615 is secured to the first key 618 alone; in the second position, the second disc spring 614 is secured to the first key 618, and the fifth disc spring 617 is secured to the second key 619 simultaneously; and in the third position, the first disc spring 613 is secured to the first key 618, and the fourth disc spring 616 is secured to the second key 619 simultaneously. The stiffness of these three positions increases from low to high, with the first position having the lowest stiffness and the third position having the highest stiffness. During use, different stiffness levels can be selected based on the patient's specific needs. After the electromagnet 608 is powered off, the compression spring 610 drives the elastic element group back to its original position. In the initial state, neither the first elastic element group nor the second elastic element group engages with the corresponding key, that is, the rotation of the housing 601 does not drive the variable stiffness shaft 604 and the ankle joint rotation axis 21 to rotate, and the gear is in neutral.

[0078] The operating principle of the ankle joint variable stiffness device 6 is as follows: when the patient's rehabilitation exercise requires adjustment to maximum stiffness, the electromagnet 608 is energized, and the second magnetic transmission plate 607 drives the second and first elastic element groups toward the electromagnet 608 by a certain distance to the third gear engagement state. This is when the first disc spring 613 engages with the first key 618 and the fourth disc spring 616 engages with the second key 619, causing the compression spring 610 to stretch. When the stiffness needs to be reduced, the current flowing into the electromagnet 608 is reduced, thereby reducing the suction force on the second magnetic transmission plate 607. This reduces the stretched length of the compression spring 610, causing it to pull the first and second elastic element groups back to the second gear or the first gear engagement state, thereby switching between different gear stiffnesses. In other words, the stiffness is switched by varying the current flowing through the electromagnet 608. When the ankle joint variable stiffness device 6 is in the initial state, neither the first elastic element group nor the second elastic element group is engaged with the key on the variable stiffness shaft 604, that is, it is in the neutral position. At this time, the winding ring 603 will not drive the ankle joint 2 to rotate. At the same time, the electromagnetic brake 605 provided on the ankle joint variable stiffness device 6 can respond to emergencies, brake in time, and reduce the wearer's chance of injury.

[0079] When the ankle joint variable stiffness device 6 is in effect, at least one group of disc springs in the first elastic element group and the second elastic element group is fixed to the key on the variable stiffness shaft 604, so the winding ring 603 will drive the ankle joint rotation axis 21 to rotate through the variable stiffness shaft 604 to complete the rehabilitation movement of the ankle joint.

[0080] Furthermore, the winding ring 603 in the ankle joint variable stiffness device 6 is connected to the ankle joint drive device 7 via a first flexible cable 40, and the winding ring in the knee joint variable stiffness device is connected to the knee joint drive device via a second flexible cable 50. The ankle joint drive device 7 is fixed on the second layer 104 of the control platform 10, as shown in FIG. Figure 27 As shown, the knee joint drive device is fixed on the first layer 103 of the control platform 10. The ankle joint drive device 7 and the knee joint drive device in the present invention have the same structure. The ankle joint drive device 7 is used as an example for description below, and the knee joint drive device is not repeated here.

[0081] Specifically, such as Figure 28 、 Figure 29 As shown, the ankle joint drive device 7 includes a drum 701 connected to the first flexible cable 40. The drum 701 is driven to rotate by a drum motor 702 to achieve the retraction and extension of the first flexible cable 40. The output shaft of the drum motor 702 is connected to the barrel shaft 703 of the drum 701 through a plum blossom coupling. The two ends of the barrel shaft 703 are respectively connected to the first bearing bracket 704 and the second bearing bracket 705 through deep groove ball bearings. The drum motor 702 is fixed to the motor bracket 706. A trapezoidal screw 707 is further provided between the first bearing bracket 704 and the second bearing bracket 705. The two ends of the trapezoidal screw 707 are respectively rotatably connected to the first bearing bracket 704 and the second bearing bracket 705. The trapezoidal screw 707 is provided with a second nut seat 708 to form a screw-nut movement with it. The second nut seat 708 is fixed to the first reversing wheel 709. The first bearing bracket 704 is fixed to the second reversing wheel 709. 10. The axles of the first and second reversing wheels 709 and 710 are parallel, and the axle of the first reversing wheel 709 is perpendicular to the shaft 703 of the drum 701. A guide rod 711 is provided between the first bearing bracket 704, the second bearing bracket 705, and the second nut seat 708, passing through the three. A three-pulley tension sensor 712 is also provided on the side of the drum 701. The three-pulley tension sensor 712 is used to measure the tension of the first flexible cable 40 and transmit the detected flexible cable tension to the controller in real time. If a significant change in tension is detected, or the tension is zero, the controller energizes the electromagnetic brake, which will then jam the variable stiffness shaft 604, causing it to stop working and reduce the risk of injury to the wearer.

[0082] A pulley transmission device connects the drum 701 and the trapezoidal screw 707. The pulley transmission device includes a first pulley 713 coaxially arranged with the drum 701, a second pulley 714 coaxially arranged with the trapezoidal screw 707, and a belt 715 connecting the first pulley 713 and the second pulley 714. A tensioning pulley 716 is provided below the belt 715. The drum motor 702 drives the drum 701 to rotate via the drum shaft 703. The first pulley 713 connected to the drum shaft 703 rotates synchronously and drives the second pulley 714 to rotate. The second pulley 714 drives the trapezoidal screw 707 to rotate, thereby displacing the second nut seat 708 to ensure that the cable exit point of the first flexible cable 40 on the drum 701 is always tangential to the first reversing pulley 709.

[0083] The operating principle of the ankle joint drive device 7 is as follows: the drum motor 702 drives the drum 701 to rotate, and the first pulley 713 fixed to the drum shaft 703 drives the second pulley 714 to rotate via the belt 715, thereby displacing the second nut seat 708 on the trapezoidal lead screw 707, causing the cable outlet point of the first flexible cable 40 wound on the drum 701 to be tangent to the first reversing wheel 709. As the drum 701 rotates, the first flexible cable 40 wound on the drum 701 is correspondingly retracted and released, thereby transmitting power to the winding ring 603, driving the winding ring 603 to rotate.

[0084] In the present invention, one end of the first flexible cable 40 is fixedly connected to the drum 701 in the ankle joint drive device 7, and the other end of the first flexible cable 40 is sequentially wound through the first deflecting pulley 709, the second deflecting pulley 710, the three-pulley tension sensor 712, and the first pulley block before being fixed to the winding ring 603 in the ankle joint variable stiffness device 6. One end of the second flexible cable 50 is fixedly connected to the drum in the knee joint drive device, and the other end of the second flexible cable 50 is sequentially wound through the first deflecting pulley, the second deflecting pulley, the three-pulley tension sensor, and the second pulley block before being fixed to the winding ring in the knee joint variable stiffness device. Specifically, the first pulley group includes a first pulley 801, a second pulley 802, a first pulley block 803, a third pulley 804, a fourth pulley 805, a fifth pulley 806, a sixth pulley 807 and a seventh pulley 808, which are arranged in sequence. The second pulley group includes an eighth pulley 809, a second pulley block 810, a ninth pulley 811, a tenth pulley 812, an eleventh pulley 813, a twelfth pulley 814 and a thirteenth pulley 815, which are arranged in sequence. The first pulley 801 is fixed to a first pulley bracket 816 on the side of the second layer board 104 of the control platform 10, and the second pulley 802 and the eighth pulley 809 are fixed to a second pulley bracket 817 on the side of the first layer board 103 of the control platform 10. Figure 32The third pulley 804, the fourth pulley 805, the fifth pulley 806, the sixth pulley 807, the seventh pulley 808, the ninth pulley 811, the tenth pulley 812, the eleventh pulley 813, the twelfth pulley 814 and the thirteenth pulley 815 are all fixed on the pulley support plate 51, and the pulley support plate 51, the first pulley block 803 and the second pulley block 810 are all fixed on the bottom plate inside the support arm 5, as shown. Figure 31 In this embodiment, the support arm 5 includes a U-shaped arm 53 and a dust cover 54. The arm 53 is fixed to the side of the control platform 10 through an L-shaped bracket 52, and the front end of the support arm 5 is fixed to the third ear seat 421 on the knee joint support frame 42. Figure 30 shown.

[0085] The route of the first flexible cable 40 is as follows: one end of the first flexible cable 40 is fixed to the reel 701 in the ankle joint drive device 7, and the other end of the first flexible cable 40 is wound around the first reversing wheel 709, the second reversing wheel 710, the pulleys in the three-pulley tension sensor 712, the first pulley 801, the second pulley 802, the first pulley block 803, the third pulley 804, the fourth pulley 805, the fifth pulley 806, the sixth pulley 807 and the seventh pulley 808 in sequence, and then is fixed to the winding ring 603 on the ankle joint variable stiffness device 6.

[0086] The second cable 50 is arranged as follows: one end of the second cable 50 is fixed to the drum in the knee joint drive device, and the other end of the second cable 50 is wound sequentially around the first reversing pulley, the second reversing pulley, the pulley in the three-pulley tension sensor, the eighth pulley 809, the second pulley block 810, the ninth pulley 811, the tenth pulley 812, the eleventh pulley 813, the twelfth pulley 814, and the thirteenth pulley 815 before being fixed to the winding ring on the knee joint variable stiffness device.

[0087] The present invention has two modes of rehabilitation training: active rehabilitation mode and passive rehabilitation mode. The active rehabilitation mode is mainly aimed at patients with certain autonomous movement ability but weak muscle strength. The robot will provide auxiliary torque according to the patient's active movement intention, enhance muscle activity ability, and promote neuromuscular remodeling. The patient's movement intention is detected and analyzed by the change of the flexible cable force of the three-pulley tension sensor, and the joint stiffness is adjusted according to the detected movement intention and joint status. When the stiffness is low, the robot provides less resistance, allowing the rehabilitation patient to move with greater freedom; when the stiffness is high, the robot provides stronger support or constraint to stabilize the patient's movement trajectory.

[0088] Passive rehabilitation is primarily for patients who have completely lost their ability to move or are in the early stages of rehabilitation. A robot guides the movement process, moving the patient's limbs along a pre-set trajectory to maintain joint mobility and prevent muscle atrophy. A training trajectory, such as joint flexion and extension, is preset, or a personalized trajectory is generated based on the patient's historical data. The robot then controls the patient's limbs to perform rehabilitation training along the set trajectory. During the rehabilitation process, the robot monitors the patient's physiological feedback (such as muscle tone and heart rate) to adjust the training intensity and stiffness in a timely manner.

[0089] These two modes can be used in combination. For example, the patient starts with the passive mode and gradually transitions to the active mode as muscle strength recovers to improve the rehabilitation effect.

[0090] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A cable-driven lower limb rehabilitation robot based on a multi-level adjustable variable stiffness device, characterized by: The device comprises a left leg exoskeleton and a right leg exoskeleton symmetrically arranged on both sides of a control platform, wherein the left leg exoskeleton and the right leg exoskeleton each comprise a tibial rod, wherein the lower end of the tibial rod is connected to a foot support plate via an ankle joint, and the upper end of the tibial rod is connected to a support arm fixed to the control platform via a knee joint; The ankle joint is connected to an ankle joint stiffness changing device, and the knee joint is connected to a knee joint stiffness changing device. The ankle joint stiffness changing device and the knee joint stiffness changing device have the same structure and each include a shell, end caps and a winding ring are fixed to both ends of the shell, a stiffness changing shaft is provided in the shell, one end of the stiffness changing shaft close to the end cap is cantilevered outside the shell and is fixedly connected to the electromagnetic brake, and one end of the stiffness changing shaft close to the winding ring is fixedly connected to the ankle joint rotation shaft or the knee joint rotation shaft through a coupling; The variable stiffness rotating shaft is provided with a first magnetic transmission plate, an elastic element group, a second magnetic transmission plate and an electromagnet in sequence from the end cover to the winding ring, the first magnetic transmission plate, the elastic element group and the second magnetic transmission plate are connected to form a whole by a connecting rod, one end of the connecting rod near the end cover is connected to the end cover by a compression spring, the elastic element group is composed of a plurality of disc springs with the same structure and different elasticities, the variable stiffness rotating shaft is provided with a key fixed to the elastic element group, the circumference of the first magnetic transmission plate and the second magnetic transmission plate are respectively provided with a slider, the slider is matched with a slide groove provided on the inner wall of the shell, the slide groove is arranged along the axial direction of the shell, when the electromagnet is energized, the second magnetic transmission plate is attracted to move in the direction of the electromagnet, thereby driving the elastic element group to slide along the direction defined by the slide groove, and the connection and fixation of each disc spring in the elastic element group to the key is achieved by controlling the current size of the electromagnet, and when the electromagnet is de-energized, the elastic element group is driven to return to its position by the compression spring; The elastic element group includes a first elastic element group consisting of a first disc spring, a second disc spring, and a third disc spring, and a second elastic element group consisting of a fourth disc spring and a fifth disc spring. The key includes a first key that cooperates with the first elastic element group and a second key that cooperates with the second elastic element group. The winding ring in the ankle joint stiffness changing device is connected to the ankle joint driving device through a first flexible cable, and the winding ring in the knee joint stiffness changing device is connected to the knee joint driving device through a second flexible cable. The ankle joint driving device and the knee joint driving device have the same structure and both include a reel connected to the first flexible cable or the second flexible cable. The reel is driven to rotate by a reel motor to achieve the retraction and extension of the corresponding flexible cable; the joint stiffness is adjusted and the power supply of the electromagnetic brake is controlled by detecting the tension of the first flexible cable or the second flexible cable.

2. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: A limiting sleeve is fixed on the connecting rod between the first elastic element group and the second elastic element group, and gaskets are fixed on the connecting rods between the disc springs of the first elastic element group, between the first elastic element group and the first magnetic transmission plate, between the disc springs of the second elastic element group, and between the second elastic element group and the second magnetic transmission plate.

3. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: The ankle joint includes an ankle joint rotation axis and an ankle joint support frame, the lower end of the tibial rod is fixedly connected to the first ear seat of the ankle joint support frame, the two ends of the ankle joint rotation axis are respectively rotatably connected to the second ear seat of the ankle joint support frame through deep groove ball bearings, a first connecting bracket is coaxially fixed to the ankle joint rotation axis, and the first connecting bracket is fixed to the second connecting bracket on the sole support plate; The knee joint includes a knee joint rotation axis and a knee joint support frame. The third ear seat of the knee joint support frame is fixed to the support arm. The two ends of the knee joint rotation axis are respectively rotatably connected to the fourth ear seat of the knee joint support frame through deep groove ball bearings. A third connecting bracket is coaxially fixed on the knee joint rotation axis, and the third connecting bracket is fixedly connected to the upper end of the tibial rod.

4. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: The tibial rod is a split structure, including an upper tibial rod and a lower tibial rod that are plug-fitted together. The upper tibial rod and the lower tibial rod are both integrally formed structures. The upper tibial rod includes a first rod body connected to the knee joint and a second rod body inserted into the lower tibial rod. The lower tibial rod includes a third rod body plug-fitted with the second rod body and a fourth rod body connected to the ankle joint. The cross-sections of the first rod body, the second rod body, the third rod body and the fourth rod body are all square, and the third rod body is a structure with an open top, a hollow interior, a closed bottom end and hollow front and rear end faces. A fixing frame is provided near the upper end of the lower tibial rod. The fixing frame is fixedly connected to the lower tibial rod, and a strap for fixing the leg is provided on the fixing frame.

5. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 4, characterized in that: The cam is fixed to the chassis and the cam is fixed to the chassis, and the cam is fixed to the chassis with a first end fixed to the chassis, and a second end fixed to the chassis is fixed to the chassis with a second end fixed to the chassis.

6. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 4, characterized in that: A spring is provided between the lower tibial rod and the first connecting bracket to provide movement buffer for the ankle joint. Two springs are provided, and the two springs are symmetrically arranged on the front and back sides of the lower tibial rod. The upper end of the spring is fixed to the upper spring seat connected to the lower tibial rod, and the lower end of the spring is fixed to the lower spring seat on the first connecting bracket.

7. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: The knee joint is provided with a limit device for limiting the rotation angle of the knee joint, and the limit device includes a first limit plate and a second limit plate symmetrically arranged on both sides of the third connecting bracket, the upper ends of the first limit plate and the second limit plate are sleeved on the knee joint rotation axis, and the lower ends of the first limit plate and the second limit plate are fixed to the left and right side surfaces of the upper tibial rod, and the limit device also includes a limit block fixed to the knee joint support frame, and the first limit plate and the second limit plate are provided with a limit surface that cooperates with the limit block.

8. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: The output shaft of the drum motor is connected to the drum shaft through a plum blossom coupling, and the two ends of the drum shaft are respectively connected to the first bearing bracket and the second bearing bracket through deep groove ball bearings. The drum motor is fixed on the motor bracket, and a trapezoidal screw is also provided between the first bearing bracket and the second bearing bracket, and the two ends of the trapezoidal screw are respectively rotatably connected to the first bearing bracket and the second bearing bracket. The trapezoidal screw is provided with a second nut seat that forms a screw nut movement with it, and a first reversing wheel is fixed on the second nut seat, and a second reversing wheel is fixed on the first bearing bracket. The first reversing wheel is parallel to the axle of the second reversing wheel, and the axle of the first reversing wheel is perpendicular to the drum shaft. A guide rod is provided between the first bearing bracket, the second bearing bracket and the second nut seat, and a three-pulley tension sensor is also provided on the side of the drum.

9. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 8, characterized in that: A pulley transmission device connecting the drum and the trapezoidal screw is provided between the two. The pulley transmission device includes a first pulley coaxially arranged with the drum, a second pulley coaxially arranged with the trapezoidal screw, and a belt connecting the first pulley and the second pulley. A tensioning pulley is provided below the belt.

10. The cable-driven lower limb rehabilitation robot based on a multi-level adjustable stiffness device according to claim 1, characterized in that: One end of the first flexible cable is fixedly connected to the drum in the ankle joint driving device, and the other end of the first flexible cable is sequentially wound around the first reversing wheel, the second reversing wheel, the three-pulley tension sensor, and the first pulley group, and then fixed to the winding ring in the ankle joint variable stiffness device; one end of the second flexible cable is fixedly connected to the drum in the knee joint driving device, and the other end of the second flexible cable is sequentially wound around the first reversing wheel, the second reversing wheel, the three-pulley tension sensor, and the second pulley group, and then fixed to the winding ring in the knee joint variable stiffness device; The first pulley group includes a first pulley, a second pulley, a first pulley block, a third pulley, a fourth pulley, a fifth pulley, a sixth pulley and a seventh pulley arranged in sequence; the second pulley group includes an eighth pulley, a second pulley block, a ninth pulley, a tenth pulley, an eleventh pulley, a twelfth pulley and a thirteenth pulley arranged in sequence, wherein: the first pulley is fixed to a first pulley bracket on the side of the second layer plate of the control platform, the second pulley and the eighth pulley are fixed to a second pulley bracket on the side of the first layer plate of the control platform, the third pulley, the fourth pulley, the fifth pulley, the sixth pulley, the seventh pulley, the ninth pulley, the tenth pulley, the eleventh pulley, the twelfth pulley and the thirteenth pulley are all fixed on a pulley support plate, and the pulley support plate, the first pulley block and the second pulley block are all fixed on the bottom plate inside the support arm.

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