Lasso-driven lower limb power-assisted exoskeleton robot

Abstract

The application discloses a lasso-driven lower-limb assisting exoskeleton robot, which comprises a lasso driver, a waist, a hip joint, a knee joint, an ankle joint and a foot. A series spring tensioning mechanism is arranged in the lasso transmission chain link, so that the lasso reciprocating movement is avoided to be relaxed, and the deformation amount of the spring is measured to indirectly calculate the lasso tension. A parallel spring gravity compensation mechanism is arranged in the hip joint, so that the driving torque of the hip joint is reduced. The knee joint adopts a cross four-bar mechanism loaded with a spring to avoid joint dislocation, and the motion friction torque is compensated through the spring compensation mechanism, so that the joint torque transmission efficiency is improved. Force and angle sensors are embedded in the hip joint and the knee joint, so that the actual assisting torque and the rotation angle of the hip joint and the knee joint can be obtained in real time, and the exoskeleton torque / position control precision and the assisting effect are improved. The application has the characteristics of small joint inertia, light weight, soft motion, high force control precision and high torque transmission efficiency.

Description

Technical Field

[0001] This invention relates to the field of assistive exoskeleton robot technology, specifically to a lasso-driven lower limb assistive exoskeleton robot. Background Technology

[0002] Wearable lower limb assistive exoskeleton robots have great potential in enhancing human motor function and improving walking efficiency. They can provide on-demand assistance to the wearer's lower limb joints, relieve leg muscle fatigue, and prevent muscle damage from prolonged or long-distance walking.

[0003] Existing rigid lower limb assistive exoskeletons have their drive motors and reducers directly mounted at the joints, using a single-degree-of-freedom linkage mechanism with a fixed center of rotation to assist the joints. This results in problems such as large size, high inertia, and joint misalignment in the exoskeleton's powered joints, severely impacting the comfort of wearing the exoskeleton. Flexible lower limb assistive exoskeletons typically use lassos to directly pull on the anchor points of the legs to achieve joint assistance. While this relaxes the constraints on the joints and avoids misalignment, it lacks rigid support and mechanical limiting capabilities, negatively impacting the safety and control precision of the exoskeleton.

[0004] Furthermore, position- or velocity-based exoskeleton control schemes often fail to adequately consider changes in the user's movement needs, resulting in poor human-machine collaboration. Torque control schemes enhance the compliance of exoskeletons, but traditional torque sensors are expensive and bulky, reducing the practicality of exoskeleton torque control. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, this invention proposes a lasso-driven lower limb assistive exoskeleton robot, which features low joint inertia, lightweight design, smooth movement, high force control precision, and high torque transmission efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A lasso-driven lower limb assistive exoskeleton robot includes a lasso actuator, a waist, a hip joint, a knee joint, and an ankle and foot joint;

[0008] The lasso actuator is connected to the hip joint at both ends via the waist, and the bottom of the hip joint is connected to the ankle joint and foot via the knee joint;

[0009] The entire lower limb exoskeleton robot is symmetrically arranged along the sagittal plane of the human body, and can simultaneously realize multi-mode movements such as synchronized squatting and standing movements of the lower limbs, cross-coordinated walking movements, lower limb following movements, and assisted movements.

[0010] The hip, knee, ankle, and foot form the exoskeleton of one leg.

[0011] The exoskeleton has 5 degrees of freedom on one leg, including 2 active degrees of freedom and 3 passive degrees of freedom. These are the active degrees of freedom for flexion / extension of the hip and knee joints, the passive degrees of freedom for external rotation / internal rotation and abduction / adduction of the hip joint, and the passive degrees of freedom for plantar flexion / dorsiflexion of the ankle and foot.

[0012] Furthermore, to improve the exoskeleton's adaptability to different wearers' body sizes, it features one degree of freedom for waist width adjustment at the waist, two degrees of freedom for thigh length adjustment at the thigh connector at the hip joint, and two degrees of freedom for lower leg length adjustment at the lower leg connector at the knee joint. These multiple degrees of freedom allow for greater overall flexibility in the exoskeleton's movement, enhancing wearing comfort.

[0013] The lasso actuator is fixed to the back of the exoskeleton via a fixed connecting plate made of carbon fiber plate.

[0014] The two motor drive modules of the lasso actuator are fixed on the motor mounting plate. The motor drive modules are symmetrically arranged along the sagittal plane of the human body and drive the left and right hip joints of the exoskeleton respectively to provide assistance to the lower limbs of the human body. The individual drive module of the lasso actuator is powered by a motor. The drive pulley is fixed to the output end of the motor. The motor drives the drive pulley to rotate, thereby driving the lasso to reciprocate and realize the remote transmission of power.

[0015] The ends of the two lassos are fixed to the drive pulleys, and the lassos are connected to the drive pulleys of the left and right hip joints respectively to realize the remote transmission of power.

[0016] The lasso changes its direction of movement via a guide pulley, passes through the hollow bolt in the sleeve and enters the sleeve. The hollow bolt in the sleeve is fixed on the drive sleeve seat. Adjusting the hollow bolt in the sleeve can adjust the initial tension of the lasso. The drive sleeve seat and the hollow bolt in the sleeve are arranged symmetrically vertically.

[0017] The guide pulley seat is connected to the hollow copper shaft. The hollow copper shaft slides in the linear bearing and drives the copper shaft seat to move. Two springs are placed on the outside of the hollow copper shaft. When the lasso reciprocates, it drives the copper shaft seat to compress or relax the two symmetrically arranged springs. The springs store or release energy, so that the lasso has positive tension at any time of movement, especially avoiding the slack phenomenon during the reciprocating motion of the lasso and improving the force transmission accuracy of the lasso.

[0018] A displacement sensor baffle, made of carbon fiber, is fixed to the copper shaft seat. The baffle surface remains in contact with the probe of the self-resetting linear displacement sensor 115, thereby measuring the spring's compression deformation. Hooke's law and the properties of the movable pulley are used to indirectly calculate the lasso tension. The torque of the drive sheave can be calculated by multiplying the lasso tension by the radius of the drive sheave, obtaining the actual output torque of the motor for closed-loop torque control, thus improving the overall torque control accuracy of the exoskeleton.

[0019] A lasso actuator is placed on the actuator fixing plate behind the waist, so that driving the hip joint does not affect the forward movement of the human body. The rear side plate of the waist has a groove, in which the waist connecting rod slides horizontally to adjust the waist width. The rear side plate of the waist covers the groove to avoid causing discomfort to the human waist when the waist connecting rod slides in the groove.

[0020] The hip joints are symmetrically arranged on both sides, and the hip joints on both sides are symmetrically arranged on the side of the waist link through joint connectors. The upper end of the passive connector is connected to the joint connector to realize passive external rotation / internal rotation movement, and the lower end is connected to the flexion connector to realize passive abduction / adduction movement.

[0021] The flexion connector rotates relative to the flexion flange, and the upper protrusion of the flexion connector slides in the arc groove of the flexion flange. The sliding position relationship between the two restricts the rotational range of the hip joint to flexion 0-120° and extension 0-30°.

[0022] The flexion flange has a hip joint bearing embedded in its central axis to reduce frictional resistance during active flexion / extension movements. The central axis of the flexion flange is connected to a hip joint angle sensor to achieve real-time angle feedback of the hip joint.

[0023] One end of the sleeve is fixed in the hollow bolt in the sleeve of the actuator, and the other end is fixed on the hip joint sleeve support. The hip joint sleeve support is fixed on the flexion connector, and the sling moves inside the sleeve.

[0024] The flexion flange is fixedly connected to the thigh connector, and power is transmitted to the hip joint drive pulley via a sling, which then drives the flexion flange and thigh connector to rotate.

[0025] A thigh plate is fixed to the thigh connector, and a strap adjustment plate is arranged on the thigh plate. The strap adjustment plate has a narrow slot, and the binding mechanism can slide along the narrow slot to adjust the binding position.

[0026] A parallel elastic gravity compensation mechanism is provided on the buckling connector and the buckling flange. The internal / external meshing gear set of the parallel elastic gravity compensation mechanism with a gear ratio of 1:2 is fixed on the buckling connector and the buckling flange respectively. The external meshing gear can connect the buckling flange and the sheave fixing flange, while the upper end of the end of the internal meshing gear is fixed to the front end of the spring copper shaft with a rope.

[0027] When the gear rotates, the rope pulls the spring copper shaft to slide within the linear bearing of the spring copper shaft seat. This causes the spring copper shaft to compress or release two symmetrically arranged springs at its fixed rear end, enabling the springs to store and release energy, thus achieving passive gravity compensation of the mechanism and reducing the torque output of the driver.

[0028] The lasso actuator is connected to the waist of the exoskeleton via an actuator fixing plate, and the two hip joints are fixed to the waist width adjustment plate of the exoskeleton via joint connectors.

[0029] The end of the exoskeleton knee joint cannula is fixed to the knee joint cannula support seat, which is fixed to the lateral femoral plate. Two loops are installed inside the cannula, and the ends of the loops are fixed to the knee joint drive wheel to transmit power to the knee joint. The knee joint drive wheel is fixedly connected to the active drive plate, and the two rotate synchronously around the joint axis. The upper end of the active drive plate is fixed to the joint axis, and a square hole is cut in the middle to embed a force sensor. The lower end has a groove, the length of which is parallel to the lower leg plate. The bearing fixed to the lateral tibial plate by bolts can slide in the groove.

[0030] The active drive plate drives the cross four-bar linkage to achieve knee joint assisted movement. Bearings and washers are used in contact between the two to reduce sliding friction. Simultaneously, a force sensor measures the driving torque in real time and feeds it back to the lasso drive controller, achieving closed-loop torque feedback control and improving torque control accuracy.

[0031] The crossbar linkage includes the lateral tibial plate, anterior crossbar, posterior crossbar, medial tibial plate, medial femoral plate, and lateral femoral plate.

[0032] The anterior / posterior crossbar is located between the medial and lateral plates (femur and tibia). The anterior and posterior crossbars are connected in the same way, with the upper end connected to the femoral lateral plate and the lower end connected to the tibial lateral plate. The two are arranged alternately, and crossbar bearings are embedded inside to reduce frictional resistance. The connecting bolts between the femoral and tibial lateral plates and the anterior and posterior crossbars will cross the movement of the crossbars during joint flexion or extension, thereby limiting the range of motion of the exoskeleton knee joint to 0-120°.

[0033] The lateral and medial femoral plates have structures similar to the femoral condyles of the human knee joint, with their lower ends connected to anterior / posterior crosslinks. The lateral and medial tibial plates have structures similar to the tibial plateau of the human knee joint, with their upper ends connected to anterior / posterior crosslinks.

[0034] A passive drive plate is fixed to the other end of the joint spindle to ensure uniform torque transmission between the medial and lateral tibial plates. The passive drive plate has the same structure and installation method as the active drive plate, but no force sensor is installed in the middle.

[0035] The cross-bar linkage structure establishes a functional relationship between the active / passive drive plates and the actual knee joint angle. An angle sensor is fixed at its center and outer side to the joint spindle and medial femoral plate, respectively. By measuring the rotation angle of the joint spindle, the rotation angle of the active / passive drive plates is measured in real time. The actual knee joint rotation angle is calculated through the functional relationship, enabling true knee joint angle feedback and improving the position control accuracy of the knee joint.

[0036] Springs are loaded onto the anterior / posterior cruciate ligaments of the human knee joint to simulate their elasticity. The upper end of the spring is connected to the spring fixing shaft, and the lower end is connected to the pull rope. The two ends of the spring fixing shaft are fixed to the spring seat and the spring fixing plate, respectively.

[0037] The pull rope is guided between the inner and outer plates and fixed to the connecting bolts between the cross link and the inner and outer tibial plates via a copper post. When the inner and outer tibial plates drive the lower leg plate and the binding mechanism to apply assistance to the lower leg, the spring will be stretched or released. According to the principle of energy conservation, the spring can compensate for the additional torque consumption caused by the friction of the mechanism's movement by storing or releasing energy, thus reducing the torque drive performance requirements of the exoskeleton knee joint.

[0038] The medial tibial plate is fixed to the upper part of the calf plate, which has a narrow slot. The binding mechanism slides along the narrow slot to adjust the binding position.

[0039] The ankle joint and foot are connected to the exoskeleton knee joint via a lower leg connector. The ankle joint shells on both sides can be connected to the ankle rotating shell and the ankle-foot connecting block. The connecting block is fixed to the foot support plate, and the ankle mechanism is formed as a whole.

[0040] An ankle joint rotation mechanism is set in the ankle rotating shell. Two rotating blocks in the ankle joint rotation mechanism are coaxially engaged. The rotating blocks are connected to the ankle rotating shell through four springs to realize the rotational movement around the center of the rotating sliding block. An ankle joint bearing is arranged at the center of rotation to reduce the friction when rotating coaxially. The foot is bound to the human foot with heel strap buckle and toe strap buckle. The foot support plate and rubber insole are used to bear the external force of the foot. The rubber insole can provide appropriate cushioning to avoid rigid collision between the mechanism and the ground.

[0041] The beneficial effects of this invention are:

[0042] The lower limb-assisted exoskeleton uses a lasso-driven transmission system, placing the drive motors, reducers, and transmission mechanisms of the joints behind the waist, rather than directly at the hip and knee joints, thus reducing the volume, weight, and rotational inertia of the joints. Furthermore, the exoskeleton's connectors are made of aerospace-grade aluminum, the plates are made of carbon fiber, and the binding mechanism uses nylon 3D-printed material, ensuring the exoskeleton's structural reliability while reducing the overall mass of the knee joint.

[0043] A spring tensioning mechanism is connected in series in the lasso transmission link of the lower limb assistive exoskeleton. The series springs can store or release energy during the reciprocating motion of the lasso, ensuring that the lasso maintains positive tension at any point in its movement. This effectively prevents slackness during reciprocating motion and improves the accuracy of force transmission. Simultaneously, a self-resetting linear displacement sensor is used to measure the spring's compression deformation. Hooke's law and the properties of movable pulleys are used to indirectly calculate the lasso tension. The actual output torque of the motor is then calculated using a torque formula, further enhancing the exoskeleton's control precision.

[0044] The flexion connector of the exoskeleton hip joint rotates relative to the flexion flange. The protrusion on the upper part of the connector can slide in the arc groove of the flange, limiting the rotational range of the exoskeleton hip joint to flexion 0-120° and extension 0-30°. This ensures that the range of motion of the exoskeleton hip joint is less than that of the human hip joint, thereby ensuring that the exoskeleton will not cause injury to the user.

[0045] A spring-gravity compensation mechanism based on internal / external meshing gears is connected in parallel within the flexion / extension structure of the exoskeleton's hip joint. The gear ratio between the internal and external meshing gears is 1:2. This specific gear ratio allows the internal meshing gear to convert the relative rotational motion of the hip joint into the linear motion of the linear spring. During hip flexion / extension, based on the principle of potential energy conservation, the mechanism's gravitational potential energy and the spring's elastic potential energy are mutually converted, thus achieving gravity compensation. Simultaneously, the gravity compensation mechanism reduces the driving torque of the hip joint, decreasing the exoskeleton's energy consumption and increasing the overall endurance of the exoskeleton while other hardware conditions remain unchanged.

[0046] The exoskeleton's knee joint flexion / extension structure employs a cross-bar linkage to mimic the variable instantaneous motion of the human knee joint, preventing misalignment between the exoskeleton and the human knee joint, reducing unwanted tangential forces between the exoskeleton and the human leg, and improving wearability. Simultaneously, the connecting bolts between the rigid cross-bar linkage and the femoral / tibial lateral plates restrict the movement of the cross-bar linkage, limiting the flexion / extension range of the exoskeleton's knee joint to 0-120°, ensuring the safety of the exoskeleton's knee joint in assisting the human body.

[0047] By loading springs into the cross four-bar linkage, the springs store or release energy through stretching or contraction. Based on the principle of energy conservation, this energy can compensate for the additional torque consumption caused by friction during mechanism movement, thereby reducing the energy consumption of the exoskeleton knee joint and improving the torque transmission efficiency of the joint. At the same time, the rigid-flexible coupling structure can reduce the instantaneous impact of the exoskeleton on the human body, improving the movement compliance of the exoskeleton knee joint.

[0048] Force and angle sensors are embedded in the hip and knee joints of the exoskeleton to obtain the actual assist torque and rotation angle of the hip and knee joints in real time. The torque and angle are fed back to the control unit of the remote lasso actuator to realize the torque / position closed-loop control of the motor, thereby improving the torque / position control accuracy of the lasso-driven exoskeleton and the lower limb assist effect.

[0049] The compression deformation of the self-resetting spring in the ankle joint can limit the range of motion of the ankle joint, realize the safe mechanical limit of the passive ankle joint, and improve the safety of the exoskeleton ankle joint. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the overall structure and degrees of freedom of a lasso-driven lower limb-assisted exoskeleton.

[0051] Figure 2 This is a schematic diagram of the exoskeleton hip / knee joint lasso actuator structure.

[0052] Figure 3 This is a schematic diagram of the waist width adjustment mechanism of the exoskeleton.

[0053] Figure 4 This is a schematic diagram of a lasso-driven hip joint structure.

[0054] Figure 5 This is a schematic diagram of the parallel elastic gravity compensation mechanism of the hip joint of the exoskeleton.

[0055] Figure 6 This is a schematic diagram of the hip joint movement state of an exoskeleton.

[0056] Figure 7 This is a motion simulation diagram of a passive parallel gravity compensation device.

[0057] Figure 8 This is a schematic diagram of the lasso-driven knee joint structure.

[0058] Figure 9 This is a schematic diagram of a cross four-bar linkage with a loading spring.

[0059] Figure 10 This is a schematic diagram of the knee joint flexion movement and mechanical limitation of the exoskeleton.

[0060] Figure 11This is a simulation diagram of the motion of a four-bar linkage with a spring loading mechanism.

[0061] Figure 12 This is a schematic diagram of the ankle joint and foot structure.

[0062] Figure 13 This is a schematic diagram of the dorsiflexion / plantarflexion movement of the ankle joint and foot mechanisms.

[0063] The invention comprises five parts: 1-lasso actuator, 2-exoskeleton waist, 3-exoskeleton hip joint, 4-exoskeleton knee joint, and 5-ankle and foot joints.

[0064] The lasso actuator includes a motor (101), a actuator sleeve seat (102), a hollow bolt in the sleeve (103), a fixed connector (104), an actuator reel (105), a lasso (106), a guide pulley (107), a pulley seat (108), a spring seat (109), a linear bearing (110), a hollow copper shaft (111), a spring (112), a copper shaft seat (113), a displacement sensor baffle (115), a self-resetting linear displacement sensor (115), and a motor mounting plate (116).

[0065] 2- The waist section includes 201 driver fixing plate, 202 rear waist plate, 203 waist width adjustment plate, and 204 front waist plate.

[0066] 3-The hip joint includes 301 joint connector, 302 passive connector, 303 flexion connector, 304 flexion flange, 305 external meshing gear, 306 internal meshing gear module, 307 spool fixing flange, 308 sleeve, 309 hip joint sleeve support, 310 sling, 311 hip joint drive spool, 312 spring copper shaft fixing front end, 313 spring copper shaft seat, 314 linear bearing, 315 spring copper shaft, 316 spring, 317 spring copper shaft fixing rear end, 318 thigh connector, 319 thigh plate, 320 strap adjustment plate, 321 binding mechanism, 322 hip joint bearing, and 323 hip joint angle sensor.

[0067] 4- The exoskeleton knee joint includes 401 knee joint cannula support, 402 cannula, 403 lasso, 404 knee joint drive spool, 405 force sensor, 406 bearing, 407 active drive plate, 408 pad, 409 lateral tibial plate, 410 crossbar bearing, 411 front crossbar, 412 rope guide and fixing copper post, 413 rear crossbar, 414 medial tibial plate, 415 binding mechanism, 416 calf plate, 417 joint spindle, 418 passive drive plate, 419 medial femoral plate, 420 angle sensor, 421 thigh connector, 422 spring fixation plate, 423 pull rope, 424 spring, 425 spring fixation shaft, 426 spring seat, and 427 lateral femoral plate.

[0068] 5- Ankle and foot components include 501 lower leg connector, 502 ankle rotating shell, 503 ankle shell, 504 rotating block, 505 spring, 506 ankle bearing, 507 ankle-foot connector, 508 heel strap buckle, 509 foot support plate, 510 toe strap buckle, and 511 rubber insole. Detailed Implementation

[0069] The present invention will now be described in further detail with reference to the accompanying drawings.

[0070] This invention aims to design a lasso-driven lower limb assistive exoskeleton robot, the overall structural composition and degree-of-freedom arrangement of which are as follows: Figure 1 As shown, the exoskeleton robot includes 1-lasso actuator, 2-exoskeleton waist, 3-exoskeleton hip joint, 4-exoskeleton knee joint, and 5-ankle and foot joints. The entire lower limb exoskeleton robot is symmetrically arranged along the sagittal plane of the human body, enabling simultaneous synchronous squatting and standing movements, cross-coordinated walking movements, lower limb following movements, and assisted movements, among other multi-modal movements. Each leg of the exoskeleton has 5 degrees of freedom, including 2 active degrees of freedom and 3 passive degrees of freedom: active degrees of freedom for hip and knee joint flexion / extension, passive degrees of freedom for hip joint external / internal rotation and abduction / adduction, and passive degrees of freedom for ankle joint plantar flexion / dorsiflexion. Furthermore, to improve the exoskeleton's adaptability to different wearer body sizes, one degree of freedom for waist width adjustment, two degrees of freedom for thigh length adjustment, and two degrees of freedom for calf length adjustment are added. These multiple degrees of freedom make the entire exoskeleton flexible in movement and improve wearing comfort.

[0071] The structure of the lower limb assisted exoskeleton lasso actuator is as follows Figure 2As shown, the actuator is fixed to the rear of the exoskeleton's waist via a fixed connector 104. The drive motor and transmission components are fixed to the motor mounting plate 116, which are symmetrically arranged along the sagittal plane of the human body, driving the hip and knee joints on the left and right sides of the exoskeleton respectively, providing assistance to the lower limbs. Each actuator unit is powered by a motor 101. The actuator pulley 105 is fixed to the output end of the motor. The motor drives the actuator pulley to rotate, thereby driving the lasso 106 to reciprocate, realizing remote power transmission. The lasso changes its direction of movement via a guide pulley 107, passes through the hollow bolt 103 into the sleeve, and is fixed to the actuator sleeve seat 102. Adjusting the hollow bolt can adjust the initial tension of the lasso. The guide pulley seat 108 is connected to the hollow copper shaft 111. The hollow copper shaft slides within the linear bearing 110, driving the copper shaft seat 113 to move. A spring 112 is placed on the outside of the hollow copper shaft. During the reciprocating motion of the lasso, the spring stores or releases energy, ensuring that the lasso maintains positive tension at all times of movement, effectively preventing slackness during reciprocating motion and improving the force transmission accuracy of the lasso. Furthermore, a displacement sensor baffle 114 is fixed on the copper shaft seat. This baffle can actuate the probe of the self-resetting linear displacement sensor 115 to measure the spring's compression deformation, indirectly calculating the lasso tension using Hooke's law and the properties of the movable pulley. Based on the lasso tension and the size of the drive sheave, the torque of the drive sheave can be calculated, yielding the actual output torque of the motor. This enables closed-loop torque control of the motor, improving the overall torque control accuracy of the assistive exoskeleton.

[0072] The structure of the waist of the exoskeleton, such as Figure 3 As shown, a lasso actuator is placed on the actuator fixing plate 201 behind the waist, which does not affect the forward movement of the human body when driving the hip and knee joints of the lower limbs. The rear side plate 202 of the waist has a groove, and the waist connecting rod 203 can slide horizontally in the groove to achieve waist width adjustment. The rear side plate 204 of the waist covers the groove to prevent the waist connecting rod from causing discomfort to the human waist when sliding in the groove.

[0073] Lasso-driven hip joint structures such as Figure 4As shown, the two hip joints are symmetrically arranged on the lumbar link via joint connectors 301. The upper end of the passive connector 302 connects to the joint connector to achieve passive external / internal rotation, and the lower end connects to the flexion connector 303 to achieve passive abduction / adduction. The flexion connector rotates relative to the flexion flange 304, and its upper protrusion slides in the arc groove of the flexion flange, limiting the rotational range of the hip joint to flexion 0-120° and extension 0-30°. The flexion flange contains a hip joint bearing 322 to reduce frictional resistance during active flexion / extension. The central axis of the flange is connected to the hip joint angle sensor 323 to achieve real-time angle feedback of the hip joint. The lasso 310 moves within the sleeve 308, one end of which is fixed in the hollow bolt of the actuator sleeve, and the other end is fixed to the hip joint sleeve support 309. Power is transmitted via a lasso to the hip joint drive pulley 311, which then drives the parallel spring gravity compensation mechanism and the thigh connector 318 to rotate. The thigh plate 319 is fixed to the thigh connector, and an adjustable strap adjustment plate 320 is arranged on it to adjust the position of the binding mechanism 321. When worn by a person, the position of the straps can be manually adjusted to improve the adaptability of the exoskeleton hip joint to human body size.

[0074] Exoskeleton hip joint parallel elastic gravity compensation mechanism such as Figure 5 As shown, an internal / external meshing gear set with a gear ratio of 1:2 is fixed on the buckling connector and the buckling flange, respectively. The external meshing gear 305 connects the buckling flange and the sheave fixing flange 307. The upper end of the end 306 of the internal meshing gear is connected to the front end 312 of the spring copper shaft by a rope. When the gear rotates, the rope pulls the spring copper shaft 315 to slide in the linear bearing 314 of the spring copper shaft seat 313. Then, it drives the rear end 317 of the spring copper shaft to compress or relax the spring 316, causing the spring to store and release energy, realizing the passive gravity compensation of the mechanism, reducing the torque output of the driver, and thus reducing the energy consumption of the driving force.

[0075] The movement state of the exoskeleton hip joint, such as Figure 6 As shown, the hip joint's abduction / adduction and external / internal rotation movements are determined by the movement state of the human lower limb. Hip flexion / extension movements are remotely driven by a lasso actuator via a lasso. Adding passive abduction / adduction and external / internal rotation to the active flexion / extension of the hip joint allows the exoskeleton's mechanical structure to better align with normal lower limb movements, effectively improving hip joint flexibility and maximizing the exoskeleton's hip joint assist effect.

[0076] With appropriate spring constants and mechanical structure parameters, the qualitative motion simulation results of the exoskeleton hip joint before and after the passive parallel gravity compensation mechanism are as follows: Figure 7As shown, during hip flexion / extension, the rope anchor point of the internal meshing gear in the gravity compensation mechanism always moves along the centerline of the thigh connector, converting the relative rotational displacement of the internal / external meshing gears into the linear displacement Δl of the spring. This achieves the mutual conversion between the gravitational potential energy of the mechanical structure and the elastic potential energy of the linear spring, ultimately realizing gravity compensation of the mechanism. After the parallel gravity compensation mechanism is connected, the torque curve profile of the lasso actuator driving the hip joint movement is significantly reduced, thereby reducing the energy consumption of the exoskeleton hip joint when assisting human movement. When other hardware conditions remain unchanged, the exoskeleton's endurance can be increased. In addition, after the parallel spring gravity compensation mechanism is connected, the peak driving torque of the hip joint mechanism is also significantly reduced, which can reduce the performance requirements of the exoskeleton on the drive motor.

[0077] Lasso-driven knee joint structures such as Figure 8 As shown, the end of the sleeve 402 is fixed to the knee joint sleeve support 401. The internal lasso 403 transmits power to the knee joint drive pulley 404. The pulley is fixedly connected to the active drive plate 407, and the two rotate synchronously around the joint main axis 417. The active drive plate drives the cross four-bar linkage to achieve knee joint assisted movement. The two are in contact using a bearing 406 and a washer 408 to reduce sliding friction. At the same time, the force sensor 405 embedded inside the active drive plate can measure the driving torque in real time and feed it back to the lasso drive controller to achieve torque closed-loop feedback control and improve torque control accuracy. The cross four-bar linkage consists of the lateral tibial plate 409, the anterior cross link 411, the posterior cross link 413, the medial tibial plate 414, the medial femoral plate 419, and the lateral femoral plate 427. The anterior / posterior cross link is located between the medial / lateral plates (femur and tibia), and the cross link bearing 410 is embedded inside to reduce frictional resistance. A passive drive plate 418 is fixed to the other end of the joint spindle to achieve uniform torque transmission between the medial and lateral tibial plates. The unique drive structure enables a functional relationship between the active / passive drive plates and the true angle of the knee joint. An angle sensor 420 (fixed to the spindle and the medial femoral plate respectively on the medial and lateral sides) measures the rotation angle of the active / passive drive plates in real time. The true knee joint rotation angle is calculated through the functional relationship, realizing true angle feedback of the knee joint and improving the position control accuracy of the knee joint.

[0078] A cross four-bar linkage with a loaded spring, such as Figure 9As shown, a spring 424 is loaded onto the anterior / posterior crosslink to simulate the elastic characteristics of the anterior and posterior cruciate ligaments of the human knee joint. The upper end of the spring is connected to the spring fixing shaft 425, and the lower end is connected to the pull rope 423. The two ends of the spring fixing shaft are fixed to the spring seat 426 and the spring fixing plate 422, respectively. The pull rope is guided by the rope between the inner and outer plates and fixed to the connecting bolts between the crosslink and the inner / outer tibial plates via the fixing copper post 412. When the inner and outer tibial plates drive the lower leg plate 416 and the binding mechanism 415 to apply assistance to the human lower leg, the spring will be stretched or released. According to the principle of energy conservation, the spring can compensate for the additional torque consumption caused by the friction of the mechanism's movement by storing or releasing energy, thereby reducing the torque drive performance requirements of the exoskeleton knee joint.

[0079] The flexion motion and mechanical limiting structure of the knee joint in an exoskeleton Figure 10 As shown, the cross four-bar linkage is integrated between the medial and lateral plates of the femur and tibia to achieve a compact design of the exoskeleton knee joint. The connecting bolts of the femoral side plate 419 and the tibial side plate 414 with the anterior cross link 411 and the posterior cross link 413 limit the range of motion of the exoskeleton knee joint to 0-120°, achieving mechanical limitation of 0° extension and 120° flexion.

[0080] With appropriate spring constants and mechanical structure parameters, the qualitative simulation results of the motion of the cross-bar linkage before and after spring loading are as follows: Figure 11 As shown, during the rotation of the cross-bar linkage, its instantaneous center of rotation O changes continuously, consistent with the rolling and sliding motion characteristics of the tibial plateau along the femoral condyle during human knee joint movement. Simultaneously, the tibial lateral plate is stretched or released by a rope through two springs (with deformations of Δx1 and Δx2, respectively). The springs can store or release energy to adjust the torque curve driving the exoskeleton knee joint, reducing the peak torque driving force of the exoskeleton knee joint. At the initial moment of knee joint rotation, the driving torque after loading the springs is negative, indicating that the joint driving torque is opposite to the direction of knee joint rotation. The lasso applies a reverse driving torque to overcome the residual torque of the springs.

[0081] The structure of the ankle and foot, such as Figure 12As shown, the ankle joint is connected to the exoskeleton knee joint via the lower leg connector 501. The ankle joint shells 503 on both sides can be connected to the ankle rotating shell 502 and the ankle-foot connecting block 507. The connecting block is fixed on the foot support plate 509, forming an integral ankle mechanism. The ankle joint rotation mechanism mainly consists of two rotating blocks 504 coaxially engaged. The blocks are connected to the ankle rotating shell via four springs 505, realizing rotational movement around the center of the rotating sliding block. The rotation center is equipped with an ankle joint bearing 506 to reduce friction during coaxial rotation. The foot is secured to the human foot with a heel strap buckle 508 and a toe strap buckle 510. The foot support plate 509 and rubber insole 511 are used to bear external forces on the foot. The rubber insole can provide appropriate cushioning to avoid rigid collisions between the mechanism and the ground.

[0082] The dorsiflexion / plantarflexion movement states of the ankle joint and foot mechanisms, as follows: Figure 13 As shown, when the passive ankle joint is subjected to torque applied during the flexion movement of the human ankle joint, the exoskeleton ankle joint passively follows the movement of the human ankle joint and foot. When there is no external torque, the mechanism returns to its original position due to the elasticity of the spring. In addition, the movement of the ankle joint is limited by the compression deformation of the spring, which realizes the safe mechanical limit of the passive ankle joint and prevents accidental injury to the human ankle joint.

[0083] Working principle of the invention:

[0084] The exoskeleton's hip and knee joints utilize a lasso-driven transmission system. A motor drives the lasso reciprocating through a driver pulley 105, transmitting power to the hip joint drive pulley 311 and the knee joint drive pulley 404 respectively, achieving remote power transmission. Placing the lasso-driven structure of the joints behind the lower back avoids the increased weight and rotational inertia at the joints caused by directly placing the motor and reducer at the joints in traditional exoskeletons, thus improving the wearing comfort of the lower limb assistive exoskeleton.

[0085] A lasso tensioning spring mechanism is connected in series in the lasso transmission link. When the lasso moves, the spring 112 is compressed or relaxed. On the one hand, the lasso can be pre-tensioned so that it always maintains positive tension. On the other hand, the compression deformation of the spring can be measured by the self-resetting linear displacement sensor 115. The actual output torque of the motor can be calculated by using Hooke's law and torque formula, so as to realize the torque closed-loop control of the motor and improve the torque control accuracy and assist effect of the exoskeleton.

[0086] A spring-gravity compensation mechanism based on internal / external meshing gears is connected in parallel within the hip joint structure. The gear ratio of the internal meshing gear 306 to the external meshing gear 305 is 1:2. This specific gear ratio allows the internal meshing gear to convert the relative rotational motion of the hip joint into the linear motion of the linear spring 316. During hip flexion / extension movements, based on the principle of potential energy conservation, the mechanism's gravitational potential energy and the spring's elastic potential energy are mutually converted, thereby achieving gravity compensation. Simultaneously, the gravity compensation mechanism reduces the driving torque of the hip joint, decreases the energy consumption of the exoskeleton actuator, and increases the overall endurance of the exoskeleton while other hardware conditions remain unchanged.

[0087] The exoskeleton knee joint employs a cross-bar linkage with cross-loaded springs. The front cross link 411 and rear cross link 413 simulate the anterior and posterior cruciate ligaments of the human knee joint. The variable instantaneous center of motion of the cross links simulates the actual physiological movement of the human knee joint. Simultaneously, two tension springs 424 are connected in parallel to the cross links to simulate the passive elasticity of the ligaments. Based on the principle of energy conservation, the tension springs can compensate for the additional torque consumption caused by friction during mechanism movement by releasing and storing energy, thereby reducing the energy consumption of the exoskeleton actuator and improving the torque transmission efficiency of the joint. At the same time, the rigid-flexible coupling structure reduces the instantaneous impact of the exoskeleton on the human body, improving the flexibility of the exoskeleton knee joint.

[0088] The flexion connector 303 of the exoskeleton hip joint rotates relative to the flexion flange 304. The protruding structure on the upper part of the connector is embedded in the arc-shaped groove of the flange, limiting the rotational range of the exoskeleton hip joint to 0-120° flexion and 0-30° extension. In the exoskeleton knee joint's cross-bar linkage, the connecting bolts between the side plate and the cross link restrict the movement of the cross link, thus limiting the flexion / extension range of the exoskeleton knee joint to 0-120°. In the ankle joint, the rotating block 504 reciprocates within the self-resetting spring 505. The compression deformation of the spring limits the range of motion of the ankle joint, achieving safe mechanical limiting of the passive ankle joint. The mechanical limiting results in the hip, knee, and ankle joints of the lower limb-assisted exoskeleton ensure that the range of motion of the exoskeleton joints is less than the range of motion of human joints, thereby ensuring that the exoskeleton will not cause injury to the user.

[0089] An angle sensor 323 is installed on the spindle of the exoskeleton hip joint flexion flange 304 to measure the actual rotation angle of the exoskeleton hip joint in real time and feed the hip joint angle back to the lasso drive control unit. A force sensor 405 is embedded inside the active drive plate 407 of the exoskeleton knee joint to measure the drive torque in real time and feed it back to the lasso drive controller, realizing closed-loop feedback control of the knee joint torque. An angle sensor 420 is installed at the passive drive plate 418 of the knee joint to measure the rotation angle of the active / passive drive plates in real time. The actual knee joint rotation angle is calculated through the angular relationship between the drive plate and the knee joint, enabling true knee joint angle feedback and improving the position control accuracy of the knee joint. The lasso drive control unit of the exoskeleton joint, combining torque and position information feedback, will greatly improve the assist effect of the exoskeleton knee joint on the human body.

Claims

1. A lasso-driven lower limb assistive exoskeleton robot, characterized in that, Including the lasso actuator (1), waist (2), hip joint (3), knee joint (4), and ankle and foot (5); The lasso actuator (1) is connected to the hip joint (3) at both ends via the waist (2), and the bottom of the hip joint (3) is connected to the ankle joint and foot (5) via the knee joint (4). The hip joint (3), the exoskeleton knee joint (4), and the ankle joint and foot (5) constitute the exoskeleton unilateral leg; The entire lower limb exoskeleton robot is arranged symmetrically along the sagittal plane of the human body; The exoskeleton has 5 degrees of freedom on one leg, including 2 active degrees of freedom and 3 passive degrees of freedom, namely the active degrees of freedom of flexion / extension of the hip joint (3) and knee joint (4), the passive degrees of freedom of external rotation / internal rotation and abduction / adduction of the hip joint (3), and the passive degrees of freedom of plantar flexion / dorsiflexion of the ankle joint and foot (5). The exoskeleton knee joint (4) includes a second sleeve (402), the end of which is fixed to the knee joint sleeve support (401). The knee joint sleeve support (401) is fixed to the lateral femoral plate (427), and two second lassos (403) are provided inside. The end of the second lasso (403) is fixed to the knee joint drive wheel (404) to transmit power to the knee joint. The knee joint drive wheel (404) is fixedly connected to the active drive plate (407), and the two rotate synchronously around the joint main axis (417). The upper end of the active drive plate (407) is fixed to the joint main axis (417), and a force sensor (405) is embedded in the middle through a square hole. The lower end has a groove, the length of which is parallel to the lower leg plate. The bearing (406) fixed on the lateral tibial plate (409) by bolts slides in the groove. The active drive plate (407) drives the cross four-bar mechanism to achieve knee joint assisted movement. The two are in contact with each other by bearing (406) and pad (408). At the same time, the force sensor (405) measures the driving torque in real time and feeds it back to the lasso drive controller to realize torque closed-loop feedback control and improve torque control accuracy. The cross-bar linkage includes the lateral tibial plate (409), the anterior cross-link (411), the posterior cross-link (413), the medial tibial plate (414), the medial femoral plate (419), and the lateral femoral plate (427). The anterior / posterior cross link is located between the medial and lateral plates. The anterior cross link (411) and the posterior cross link (413) are connected in the same way. The upper end is connected to the femoral lateral plate and the lower end is connected to the tibial lateral plate. The two are arranged alternately. The cross link bearing (410) is embedded inside to reduce frictional resistance. The connecting bolts of the femoral medial plate (419) and the tibial medial plate (414) to the anterior cross link (411) and the posterior cross link (413) will restrict the movement of the cross link when the joint is flexed or extended, thereby limiting the range of motion of the exoskeleton knee joint flexion / extension to 0-120°. The structures of the lateral femoral plate (427) and medial femoral plate (419) are similar to the structure of the femoral condyle of the human knee joint, and their lower ends are connected to the anterior / posterior cross links; the structures of the lateral tibial plate (409) and medial tibial plate (414) are similar to the structure of the tibial plateau of the human knee joint, and their upper ends are connected to the anterior / posterior cross links. The other end of the joint spindle (417) is fixed with a passive drive plate (418) to achieve uniform torque transmission of the medial / lateral tibial plates. The passive drive plate (418) has the same structure and installation method as the active drive plate (407), and no force sensor is installed in the middle. The cross-bar drive structure makes the active / passive drive plate and the actual angle of the knee joint have a certain functional relationship. The center and outer side of the angle sensor (420) are fixed to the joint main axis (417) and the medial femoral plate (419) respectively. The rotation angle of the active / passive drive plate is measured in real time by measuring the rotation angle of the joint main axis (417). Spring 2 (424) is loaded on the front / rear cross link to simulate the elastic properties of the anterior and posterior cruciate ligaments of the human knee joint. The upper end of spring 2 (424) is connected to the spring fixing shaft (425), and the lower end is connected to the pull rope (423). The two ends of the spring fixing shaft (425) are fixed on the spring seat (426) and the spring fixing plate (422) respectively. The pull rope (423) is guided by the rope between the inner and outer plates and fixed to the copper column (412) on the connecting bolt between the cross link and the inner / outer plates of the tibia. When the inner and outer plates of the tibia drive the lower leg plate (416) and the second binding mechanism (415) to apply assistance to the lower leg of the human body, the second spring (424) will be stretched or relaxed. The medial tibial plate (414) is fixed to the upper end of the calf plate (416). The calf plate (416) has a long and narrow slot. The binding mechanism 2 (415) slides along the long and narrow slot to adjust the binding position.

2. The lasso-driven lower limb assistive exoskeleton robot according to claim 1, characterized in that, One degree of freedom for waist width adjustment is set at the waist (2) of the exoskeleton, two degrees of freedom for thigh length adjustment are set at the thigh connector (318) at the hip joint (3), and two degrees of freedom for lower leg length adjustment are set at the lower leg connector (501) at the knee joint (4).

3. The lasso-driven lower limb assistive exoskeleton robot according to claim 1, characterized in that, The lasso actuator (1) is fixed to the back of the waist of the exoskeleton (2) by a fixed connecting plate (104), which is made of carbon fiber plate material; The two motor drive modules of the lasso actuator (1) are fixed on the motor mounting plate (116). The motor drive modules are arranged symmetrically along the sagittal plane of the human body and drive the hip joints on the left and right sides of the exoskeleton respectively to provide assistance to the lower limbs of the human body. The single drive module of the lasso actuator (1) is powered by the motor (101). The drive wheel (105) is fixed at the output end of the motor (101). The motor (101) drives the drive wheel (105) to rotate, thereby driving the lasso (106) to reciprocate and realize the remote transmission of power. The ends of the two lassos (106) are fixed to the drive spools (105), and the lassos (106) are respectively connected to the drive spools (311) of the left and right hip joints, thereby realizing the remote transmission of power.

4. A lasso-driven lower limb assistive exoskeleton robot according to claim 3, characterized in that, The lasso (106) changes its direction of movement through the guide pulley (107), passes through the hollow bolt (103) into the sleeve, and is fixed on the drive sleeve seat (102). The initial tension of the lasso (106) is adjusted by adjusting the hollow bolt (103). The drive sleeve seat (102) and the hollow bolt (103) are arranged symmetrically up and down. The pulley seat (108) of the guide pulley (107) is connected to the hollow copper shaft (111). The hollow copper shaft (111) slides in the linear bearing (110) and drives the copper shaft seat (113) to move. Two springs (112) are placed on the outside of the hollow copper shaft (111). When the lasso (106) reciprocates, it drives the copper shaft seat (113) to compress or relax the two symmetrically arranged springs (112). The springs (112) store or release energy, so that the lasso (106) has positive tension at any moment of movement. The displacement sensor baffle (114) is fixed on the copper shaft seat (113). The displacement sensor baffle (114) is made of carbon fiber plate material. The plate surface of the displacement sensor baffle (114) is always in contact with the probe of the self-resetting linear displacement sensor (115).

5. A lasso-driven lower limb assistive exoskeleton robot according to claim 1, characterized in that, The lasso driver (1) is placed on the driver fixing plate (201) behind the waist (2). The rear side plate (202) of the waist has a groove. The waist connecting rod (203) slides horizontally in the groove to realize the waist width adjustment. The front side plate (204) of the waist covers the groove.

6. A lasso-driven lower limb assistive exoskeleton robot according to claim 5, characterized in that, The hip joints (3) are symmetrically arranged on both sides. The hip joints (3) on both sides are symmetrically arranged on the side of the waist link (203) through the joint connector (301). The upper end of the passive connector (302) is connected to the joint connector (301) to realize passive external rotation / internal rotation movement, and the lower end is connected to the flexion connector (303) to realize passive abduction / adduction movement. The flexion connector (303) and the flexion flange (304) rotate relative to each other. The upper protrusion of the flexion connector (303) slides in the arc groove of the flexion flange (304). The sliding position relationship between the two restricts the rotation range of the hip joint (3) to flexion 0-120° and extension 0-30°. The flexion flange (304) has a hip joint bearing (322) embedded on its central axis to reduce frictional resistance during active flexion / extension movements. The central axis of the flexion flange (304) is connected to the hip joint angle sensor (323) to realize real-time angle feedback of the hip joint. One end of the sleeve (308) is fixed in the hollow bolt (103) of the sleeve of the driver, and the other end is fixed on the hip joint sleeve support (309). The hip joint sleeve support (309) is fixed on the flexion connector (303), and the sling (310) moves inside the sleeve (308). The flexion flange (304) is fixedly connected to the thigh connector (318), and the power is transmitted to the hip joint drive pulley (311) via the lasso (310), which then drives the flexion flange (304) and the thigh connector (318) to rotate. The thigh connector (318) is fixed with a thigh plate (319), and a strap adjustment plate (320) is arranged on the thigh plate (319). The strap adjustment plate (320) has a long and narrow slot. The binding mechanism (321) slides along the long and narrow slot to adjust the binding position.

7. A lasso-driven lower limb assistive exoskeleton robot according to claim 6, characterized in that, A parallel elastic gravity compensation mechanism is provided on the buckling connector (303) and the buckling flange (304). The internal / external meshing gear set of the parallel elastic gravity compensation mechanism with a gear ratio of 1:2 is fixed on the buckling connector (303) and the buckling flange (304) respectively. The external meshing gear (305) connects the buckling flange and the sheave fixing flange (307), while the upper end of the end (306) of the internal meshing gear is connected to the front end (312) of the spring copper shaft by a rope. When the gear rotates, the rope pulls the spring copper shaft (315) to slide in the linear bearing (314) of the spring copper shaft seat (313), which then drives the fixed rear end (317) of the spring copper shaft to compress or relax the two symmetrically arranged springs (316), causing the springs (316) to store and release energy, realize the passive gravity compensation of the mechanism, and reduce the torque output of the driver.

8. A lasso-driven lower limb assistive exoskeleton robot according to claim 1, characterized in that, The lasso actuator (1) is connected to the waist of the exoskeleton (2) via an actuator fixing plate (201), and the two hip joints (3) are fixed to the waist link (203) of the exoskeleton via joint connectors (301).

9. A lasso-driven lower limb assistive exoskeleton robot according to claim 1, characterized in that, The ankle joint and foot (5) are connected to the exoskeleton knee joint (4) via the lower leg connector (501). The ankle joint shells (503) on both sides are connected to the ankle rotating shell (502) and the ankle-foot connecting block (507). The connecting block (507) is fixed on the foot support plate (509), and the ankle mechanism is formed as a whole. An ankle joint rotation mechanism is provided in the ankle rotating shell (502). Two rotating blocks (504) in the ankle joint rotation mechanism are coaxially engaged. The rotating blocks (504) are connected to the ankle rotating shell through four springs (505) to realize the rotational movement around the center of the rotating blocks (504). An ankle joint bearing (506) is arranged at its rotation center to reduce the friction when rotating coaxially. The foot is bound to the human foot with heel strap buckle (508) and toe strap buckle (510). Foot support plate (509) and rubber insole (511) are used to bear the external force of the foot.

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