Rope-driven ankle-foot exoskeleton robot and control method

Abstract

The invention discloses a rope-driven ankle-foot exoskeleton robot and a control method, the ankle-foot exoskeleton robot comprises a two-way driving module, a rope-driven driving module, a rope-driven driving module, a rope-driven driving module, a rope-driven driving module, a rope-driven driving module and a rope-driven driving module, the lower leg binding module is arranged on the lower leg, and the ankle-foot fixing module is worn on the foot. The two-way driving module transmits power to the shank binding module and the ankle and foot fixing module in sequence through a rope transmission device, and therefore ankle joints are driven to do dorsal flexion or plantar flexion motion. The ankle-foot exoskeleton robot is driven by a rope and has the advantages of being light in weight, easy to deploy, good in flexibility and the like, modular design is adopted for the assemblies, the relative positions of all the modules are easy to adjust, and the ankle-foot exoskeleton robot can adapt to the difference between individuals in the wearing process; the position of the rope transmission device on the shank binding structure is easy to adjust, and rapid conversion between plantar flexion and dorsal flexion can be achieved on the basis that the freedom degree of movement of the lower limbs of the patient is not interfered.

Description

Technical Field

[0001] The present invention relates to the technical field of rehabilitation robots, and in particular to a rope-driven ankle-foot exoskeleton robot and a control method thereof. Background Art

[0002] With the aging of the population, the proportion of the elderly population is growing rapidly. Among the elderly, the incidence of stroke is high and is showing a trend of younger age. Stroke patients often have various sequelae, of which about 80% of patients are accompanied by motor dysfunction, which seriously affects their quality of daily life. In particular, for hemiplegic patients, due to their asymmetric gait, metabolic loss increases by about 60%. For these patients with severely impaired motor function, if they do not receive scientific and effective rehabilitation treatment, they may suffer from lifelong disability. High-density and repetitive rehabilitation training has been proven to accelerate the patient's rehabilitation process, and professional rehabilitation physicians in rehabilitation institutions can provide patients with targeted rehabilitation training. However, problems such as insufficient rehabilitation medical resources, shortage of professional talents, and low training efficiency in China are still prominent. Many patients prefer to receive rehabilitation treatment outside professional rehabilitation institutions. The emergence of rehabilitation robots provides effective support for the recovery of patients' motor functions and alleviates the problem of increasingly scarce rehabilitation medical resources to a certain extent. Through intelligent and automated technologies, such robots can provide patients with high-density and repetitive training, promote the rehabilitation process, and become a powerful supplement to traditional rehabilitation training.

[0003] Rigid exoskeletons are composed of a large number of rigid links and can bear the patient's weight. They are mainly suitable for patients with high paraplegia, severe hemiplegia and long-term weight-bearing workers. However, rigid exoskeletons have problems such as high energy consumption, large size, heavy weight, and poor portability. Due to insufficient control accuracy and limited algorithm generalization ability, they may limit the patient's lower limb movement. Its large inertia makes it difficult to achieve low-level assistance, and the limited reverse drive ability may cause secondary damage to the patient. In addition, since the center of rotation of the joints varies due to individual differences when the patient walks, rigid exoskeletons are prone to joint misalignment. Although this problem can be partially alleviated by complex joint adaptive alignment structures, it will also increase the complexity and weight of the rigid structure, further limiting its application in rehabilitation scenarios outside the laboratory. The rise of flexible lower limb exoskeleton technology has effectively overcome many of the shortcomings of traditional rigid exoskeletons. Compared with rigid structures, flexible exoskeletons have low energy consumption, light weight, strong comfort and high flexibility without interfering with the natural kinematics of the human body. However, due to the limited load-bearing capacity, low power transmission efficiency and insufficient control accuracy of flexible exoskeletons, their applicability is mainly concentrated in the patient group whose lower limbs can independently support body weight and have certain motor functions. Compared with the traditional motor direct drive system, the rope transmission technology can effectively isolate the motor inertia, thereby optimizing the dynamic response of the human-machine system, and its good flexibility can minimize the interference with the freedom of movement of the lower limbs of the human body. This feature gives it a significant advantage in rehabilitation scenarios, especially for gait training and rehabilitation tasks that require flexible assistance.

[0004] In order to solve the above problems, the prior art has proposed some devices and methods. For example, Announcement No. CN217123170U discloses a rope-driven ankle-foot exoskeleton, but the mechanism realizes passive dorsiflexion assistance through a torsion spring, and there is no tension measurement unit, which makes it difficult to realize personalized dorsiflexion assistance needs. Announcement No. CN210210390U discloses a reconfigurable flexible walking exoskeleton system that can adapt to relatively complex external environments and realize unidirectional assistance for the three joints of the hip, knee, and ankle, but the mechanism relies on multiple motor drive units, the system is complex and cannot realize dorsiflexion assistance. Announcement No. CN202410774973A discloses a modular ankle-foot exoskeleton that can realize hip flexion / extension assistance and ankle plantar flexion / dorsiflexion assistance, which is suitable for people with lower limb movement disorders, but the core drive unit is completely separated from the human body, making it difficult to apply to daily rehabilitation training. Announcement No. CN118576194A discloses a gait detection system based on a rigid foot exoskeleton, which can accurately divide the gait cycle into four stages based on Hall sensors, encoders and posture sensors, but the exoskeleton does not have lower limb assistance functions. Announcement No. CN118453355A discloses a variable stiffness ankle-foot assistance exoskeleton that can simulate the changing ankle joint stiffness, but the structure is too complex, and the additional mass applied to the ankle joint is likely to have a negative impact on human energy consumption. Announcement No. CN202011014479A and Announcement No. US2023150114A1 respectively disclose a passive ankle-foot assistance exoskeleton, but the passive structure is difficult to achieve personalized assistance needs and has no dorsiflexion assistance function. Announcement No. US11464700B2 and US11324655B2 respectively disclose a rope-driven exoskeleton, but the structure is difficult to deploy multiple sensors to achieve accurate gait division, and its calf suspension anchor point may be offset during the driving process, making it difficult to achieve precise position control. Summary of the invention

[0005] The present invention proposes a rope-driven ankle-foot exoskeleton robot and a control method, which solves the problem that existing flexible exoskeleton robots are difficult to accurately identify gait based on the structural characteristics of the exoskeleton itself.

[0006] In order to solve the above technical problems, the present invention provides a rope-driven ankle-foot exoskeleton robot, comprising: a bidirectional driving module, which is arranged above the iliac crest of the human body and is sequentially connected to a calf binding module arranged at the calf and an ankle-foot fixing module worn on the foot through a rope transmission device;

[0007] The bidirectional driving module transmits power to the calf binding module and the ankle-foot fixing module in sequence through the rope transmission device, thereby driving the ankle joint to perform dorsiflexion or plantar flexion movement.

[0008] Preferably, the bidirectional drive module includes a joint motor, and a first deep groove ball bearing, an assembled winding wheel and a second deep groove ball bearing are arranged in sequence along the axial direction of the joint motor, the assembled winding wheel includes an inner wheel, a middle wheel and an outer wheel, the inner wheel is fixed to the inner ring of the first deep groove ball bearing, and the center axis of the outer wheel is fixed to the inner ring of the second deep groove ball bearing.

[0009] Preferably, the rope transmission device includes a dorsiflexion side Bowden cable core and a plantar flexion side Bowden cable core, the upper ends of the dorsiflexion side Bowden cable core and the plantar flexion side Bowden cable core are respectively fixedly wound on the inner and outer wheels of the assembled winding wheel, and the lower ends are respectively fixedly connected to the toe fixing device and the heel fixing device of the ankle-foot fixation module.

[0010] Preferably, a BOA lacing system is provided at the rear side of the heel fixing device, a first hanging ring device and a second hanging ring device are provided at both sides of the BOA lacing system, a first fixed pulley and a second fixed pulley are provided at both sides of the lower end of the first hanging ring device, and a third fixed pulley and a fourth fixed pulley are provided at both sides of the lower end of the second hanging ring device;

[0011] The ropes on both sides of the BOA lacing system pass through the wire holes on the first fixed pulley, the first hanging ring device, the second fixed pulley, the third fixed pulley, the second hanging ring device, the fourth fixed pulley and the toe fixing device respectively. The tightness of the rope is changed by rotating the BOA knob of the BOA lacing system to adjust the degree of fixation of the wearer's foot. At the same time, the tightness of the rope can be used as a basis for gait recognition.

[0012] Preferably, the first hanging ring device comprises a winding wheel, a pulling rope is fixedly wound on the winding part of the winding wheel, a torsion spring is welded on one side of the winding wheel, and the end of the pulling rope passes through the hanging ring and is fixed by using a first clamp.

[0013] The present invention also provides a control method for a rope-driven ankle-foot exoskeleton robot, which is applicable to the above-mentioned rope-driven ankle-foot exoskeleton robot and comprises the following steps:

[0014] Step S1: collecting gait data of the wearer during walking;

[0015] Step S2: identifying the current gait phase of the wearer according to the gait data, and calculating the control parameters of the bidirectional driving module according to the current gait phase and the expected ankle joint motion trajectory;

[0016] Step S3: controlling the bidirectional driving module to transmit power to the calf binding module and the ankle-foot fixing module according to the control parameters to assist the wearer in walking;

[0017] Step S4: dynamically adjusting the control parameters according to the actual motion trajectory of the wearer fed back by the first hanging ring device and the inertial sensor;

[0018] Step S5: Repeat steps S1 to S4 until the wearer completes rehabilitation training.

[0019] Preferably, when identifying the current gait phase of the wearer according to the gait data in step S2, an adaptive threshold iteration method is used to compensate for disturbances in the gait data collection process, and the expression of the adaptive threshold iteration method is:

[0020]

[0021] In the formula, φ th is the encoder threshold, the initial value is set to 180°; is the average value of the maximum encoder value in the three historical gait cycles; It is the average of the minimum encoder values ​​in the three historical gait cycles.

[0022] Preferably, the control parameters of the bidirectional drive module are calculated according to the current gait stage and the expected ankle joint motion trajectory as described in step S2, including the following steps: when it is detected that the wearer's gait enters the swing phase, a force / position hybrid control algorithm is used to implement dorsiflexion assistance; when it is detected that the wearer's gait enters the initial support phase and the joint motor has returned to the initial rotation angle, it is determined whether the expected force at the end of the Bowden cable is greater than 0 at this time. If so, the preload is started, and the first displacement of the rope is implemented by force-based iterative position control. After the preload is reached, a stiffness adaptive force control algorithm is used to implement the second displacement of the rope to implement plantar flexion assistance.

[0023] Preferably, the force / position hybrid control algorithm is expressed as:

[0024]

[0025] In the above formula, k represents the kth gait cycle, θ(k) is the angular control value of the motor in the kth gait cycle; k α is the position scale factor; is the desired dorsiflexion angle The maximum dorsiflexion angle measured in the previous gait cycle The difference between the two; ω(k) is the motor rotation angle of the kth gait cycle; k β is the force / speed proportionality coefficient; ΔF is the desired dorsiflexion assist force F df The maximum dorsiflexion assisting force F at the end of the previous gait cycle d_last difference.

[0026] Preferably, the stiffness adaptive force control algorithm is expressed as:

[0027]

[0028] s(i)=s d (k)+Δs(i-1);

[0029]

[0030] Δs(i-1)=s d (i-1)-s m (i-1);

[0031]

[0032] In the above formula, i is the discrete phase between a single gait cycle, x e (i) is the displacement of the rope end after the preload is reached; is the maximum rope-type variable corresponding to the historical peak tension; s(i) is the stiffness compensation; F d (i) is the expected force trajectory at the end of the rope; F m (i) is the tension at the end of the rope measured by the tension sensor; C is the auxiliary force constant; s d (k) is the stiffness parameter; Δs(i) is the total stiffness coefficient compensation; F l p (k-1) and The rope is loaded / unloaded to the k-1th gait cycle respectively. The size of the auxiliary force at s d (i) and s m (i) are the expected stiffness parameters of the human-machine system and the identified stiffness parameters of the human-machine system at phase i; 1 / n is the ratio of the rope end type variable to the maximum rope type variable corresponding to the historical peak tension at phase i-1.

[0033] The benefits of the present invention include at least: the bidirectional drive module, the calf binding module and the ankle-foot fixation module are connected by a rope transmission device. Compared with the rigid connecting rod transmission, the rope transmission method has the advantages of light weight and high flexibility, and can more finely adjust the output power size and direction, avoid the motion interference problem caused by the rigid structure, and can better adapt to the complex motion curves of the human lower limbs; and because of the reduction of complex mechanical joints and connecting rod structures, the exoskeleton robot as a whole is lighter, reducing the burden on users. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic diagram of the overall structure of an ankle-foot exoskeleton robot according to an embodiment of the present invention;

[0035] Figure 2 An exploded view of a bidirectional driving module according to an embodiment of the present invention;

[0036] Figure 3A schematic diagram of the structure of a core driver module according to an embodiment of the present invention;

[0037] Figure 4 A schematic diagram of a calf binding structure according to an embodiment of the present invention;

[0038] Figure 5 It is a structural schematic diagram of a rope transmission device according to an embodiment of the present invention;

[0039] Figure 6 It is a schematic diagram of the right side structure of the ankle-foot fixation module according to an embodiment of the present invention;

[0040] Figure 7 It is a schematic diagram of the left structure of the ankle-foot fixation module according to an embodiment of the present invention;

[0041] Figure 8 It is a structural schematic diagram of a first lifting ring device according to an embodiment of the present invention;

[0042] Fig. 9 It is a schematic diagram of a mid-support gait detection device according to an embodiment of the present invention;

[0043] Fig.10 It is a schematic diagram of a device for detecting gait at the end of support phase according to an embodiment of the present invention;

[0044] Fig.11 This is a schematic diagram of gait division results according to an embodiment of the present invention;

[0045] Fig.12 Schematic diagram of the flow of the force / position hybrid control algorithm according to an embodiment of the present invention;

[0046] Fig.13 Schematic diagram of the flow of a force control algorithm based on stiffness adaptation according to an embodiment of the present invention;

[0047] Fig.14 A three-dimensional view of a tension-displacement-system stiffness curve of an embodiment of the present invention;

[0048] Fig.15 This is the trajectory tracking result using traditional PD control;

[0049] Fig.16 This is a trajectory tracking result of the force control based on stiffness adaptation according to an embodiment of the present invention.

[0050] In the figure: 1-bidirectional drive module; 11-joint motor; 12-first deep groove ball bearing; 13-assembled winding wheel; 131-inner wheel; 132-middle wheel; 133-outer wheel; 14-second deep groove ball bearing; 15-motor fixed housing; 16-winding wheel fixed base; 17-winding wheel fixed outer seat; 101-power supply module; 102-upper control unit; 103-chassis inner flip cover; 2-calf binding module; 21-calf binding lining; 211-binding force preloading structure structure; 212-non-elastic nylon strap; 22-non-elastic Velcro fixing strap; 23-flexible strap structure; 24-zipper structure; 3-ankle-foot fixation module; 31-toe fixation device; 311-dorsiflexion side fixed anchor point; 312-toe limit structure; 313-forefoot support structure; 314-forefoot fixing wing; 315-first pull ring; 316-second clamp; 32-heel fixation device; 321-BOA lacing system; 322-first lifting ring device; 3221-reel ; 3222-pull rope; 3223-torsion spring; 3224-hanging ring; 3225-first clamp; 3226-encoder support base; 3227-winding wheel support base; 323-second lifting ring device; 3231-tension spring fixing seat; 3232-tension spring; 3233-hanging ring; 324-first fixed pulley; 325-second fixed pulley; 326-third fixed pulley; 327-fourth fixed pulley; 328-plantar flexion side fixed anchor point; 329-toothed belt fixing structure; 3210- Fine-adjusting buckle fixing structure; 3211-inertial sensor fixing structure; 3212-second pull ring; 3213-third clamp; 33-arch strap; 4-rope transmission device; 401-dorsiflexion side Bowden wire core; 402-plantar flexion side Bowden wire core; 411-dorsiflexion side Bowden wire tube; 412-plantar flexion side Bowden wire tube; 421-dorsiflexion suspension anchor point fixing belt; 4211-dorsiflexion suspension anchor point; 422-plantar flexion suspension anchor point fixing belt; 4221-plantar flexion suspension anchor point; 430-nylon buckle. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0052] During the movement of the lower limbs of the human body, the peak power output of the ankle joint is about four times that of the hip joint and the knee joint, and it is the joint with the highest energy output in the lower limbs. The current rigid ankle-foot exoskeleton is easy to increase the discomfort of the human body due to the high inertia and impact force caused by the large mass attached to the lower limbs, and even cause secondary injuries to the wearer. Flexible exoskeletons are usually composed of flexible textiles and ropes, which can better fit the curve of the human body, adapt to lower limbs of different sizes, and have lighter weight and higher comfort. Rope drive simulates the contraction of the calf muscles by shortening the distance between the anchor points to achieve power assistance. At the same time, the heavier core drive unit can be installed near the center of mass of the human body or completely separated from the human body to minimize the metabolic loss caused by the mass attached to the human body by the exoskeleton. However, due to the introduction of a large number of flexible components, some rigid sensor modules used for gait recognition are difficult to deploy stably. Therefore, it is very necessary to propose a flexible ankle-foot exoskeleton that can meet the needs of multi-degree-of-freedom rehabilitation of the ankle joint, adapt to differentiated individuals, and realize accurate gait recognition based on the structural characteristics of the flexible exoskeleton itself.

[0053] Based on the above background, the embodiments of the present invention provide Figure 1 A rope-driven ankle-foot exoskeleton robot shown mainly includes a bidirectional driving module 1, a calf binding module 2, and an ankle-foot fixation module 3. The bidirectional driving module 1 is connected to the calf binding module 2 and the ankle-foot fixation module 3 in sequence through a rope transmission device 4. The main mass of the entire exoskeleton robot is concentrated on the bidirectional driving module 1, and the main mass of the exoskeleton is distributed close to the center of mass of the human body, thereby reducing the energy consumption of the human body increased by the additional mass of the exoskeleton. The calf binding module 2 fixes the suspension anchor point on both sides of the sagittal plane of the calf, so that the force output by the core driving module can be transmitted to the ankle-foot fixation module 3 through the force conduction structure, thereby simulating the contraction and extension of the calf muscles to apply auxiliary force to the wearer's ankle joint.

[0054] like Figure 2 As shown, the bidirectional drive module 1 includes a joint motor 11, and a first deep groove ball bearing 12, an assembled winding wheel 13 and a second deep groove ball bearing 14 are sequentially arranged along the axial direction of the joint motor 11. The assembled winding wheel 13 is radially fixed to the shaft of the joint motor 11 by 6 hexagon socket screws. The assembled winding wheel 13 includes an inner wheel 131, a middle wheel 132 and an outer wheel 133, thereby realizing bidirectional drive. The inner wheel 131 is fixed to the inner ring of the first deep groove ball bearing 12, thereby reducing the radial force added to the assembled winding wheel 13, and the central axis of the outer wheel 133 is fixed to the inner ring of the second deep groove ball bearing 14.

[0055] The bidirectional drive module 1 also includes a motor fixed housing 15, a winding wheel fixed base 16 and a winding wheel fixed outer seat 17. Among them, the joint motor 11 is fixed to the winding wheel fixed base 16 by four cross round head screws, and the motor fixed housing 15 is fixed to the winding wheel fixed base 16, which further reduces the radial vibration of the joint motor 11. The outer ring of the first deep groove ball bearing 12 is fixed in the annular groove of the motor fixed housing 15, and the outer ring of the second deep groove ball bearing 14 is fixed in the annular groove of the winding wheel fixed outer seat 17.

[0056] like Figure 3 As shown, the bidirectional drive module 1 is arranged in the core drive module, and the core drive module also includes a chassis and a waist binding module. The waist binding module binds the chassis above the iliac crest of the human body through a non-elastic waist belt. To ensure the firmness of wearing, the strap is made of nylon material. At the same time, to ensure the comfort of wearing, the lining of the belt uses cotton material as a buffer medium for force loading. Several bidirectional drive modules can be installed and fixed in the chassis, and the power supply module 101 and the upper control unit 102 are placed and managed separately, wherein the upper control unit 102 is placed on the upper part of the inner flip plate 103 of the chassis, which is used to manage the upper control and can be flexibly adjusted. All sensor processing units and power management modules are installed at the lower part of the inner flip plate 103 of the chassis. Normally, no intervention is required, and maintenance or adjustment is only performed when necessary.

[0057] like Figure 4 As shown, the calf binding module 2 includes a calf binding lining 21, a non-elastic Velcro fixing strap 22 and a flexible strap structure 23. Since the calf binding lining 21 is in direct contact with the human calf skin, although the rough material can increase the friction force to prevent the binding material from sliding on the skin surface, it may cause the skin to be damaged to varying degrees. By adopting cotton material and increasing the contact area with the skin surface, the surface contact force can be increased while ensuring the wearing comfort. The introduction of elastic material will reduce the system bandwidth, so a number of non-elastic nylon straps 212 are longitudinally sewn on the outside of the cotton calf binding lining 21 to limit the longitudinal stretching of the calf binding module 2. Part of the space is reserved on the side of the calf binding module 2 that contacts the front side of the calf for sewing the flexible strap structure 23 and the binding force preloading structure 211, and a zipper structure 24 is longitudinally sewn on the inside of the calf binding module 2. The wearer can quickly put on and take off the binding structure and flexibly adjust the tightness of the binding module through the flexible binding structure 23, so that the calf binding module 2 can adapt to wearers of different physiques, is easy to put on and take off, and has good comfort. The non-elastic Velcro fixing strap 22 is a Velcro mother tape, which is sewn horizontally on the calf binding lining 21 and the non-elastic nylon belt 212, and is divided into four longitudinal layers from top to bottom and arranged in parallel. The front area of ​​the calf binding lining is also reserved for the rope transmission device 4.

[0058] like Figure 5 As shown, the rope transmission device 4 includes a dorsiflexion side Bowden wire core 401 and a plantar flexion side Bowden wire core 402. The dorsiflexion side Bowden wire core 401 and the plantar flexion side Bowden wire core 402 are respectively arranged in a dorsiflexion side Bowden wire tube 411 and a plantar flexion side Bowden wire tube 412. The upper ends of the dorsiflexion side Bowden wire tube 411 and the plantar flexion side Bowden wire tube 412 are fixed to the wire tube guide groove of the winding wheel fixed base 16, and the lower ends are fixedly connected to the wire tube guide grooves on the toe fixing device 31 and the heel fixing device 32. The upper ends of the dorsiflexion side Bowden wire core 401 and the plantar flexion side Bowden wire core 402 are respectively fixedly wound on the inner and outer wheels of the assembled winding wheel 13, and the lower ends are respectively fixedly connected to the toe fixing device 31 and the heel fixing device 32 of the ankle-foot fixing module 3.

[0059] The rope transmission device 4 also includes a dorsiflexion suspension anchor point fixing belt 421 and a plantar flexion suspension anchor point fixing belt 422. The dorsiflexion suspension anchor point fixing belt 421 and the plantar flexion suspension anchor point fixing belt 422 are respectively provided with a dorsiflexion suspension anchor point 4211 and a plantar flexion suspension anchor point 4221. The outer side of the dorsiflexion suspension anchor point fixing belt 421 and the plantar flexion suspension anchor point fixing belt 422 is made of a non-elastic nylon belt material, and the inner side is a Velcro sub-belt, and the dorsiflexion suspension anchor point 4211 and the plantar flexion suspension anchor point 4221 can be fixed to the non-elastic Velcro fixing strap 22 on the outer side of the dorsiflexion suspension anchor point fixing belt 421 and the plantar flexion suspension anchor point fixing belt 422. The rope transmission device 4 also includes a nylon buckle 430. By adjusting the tightness of the dorsiflexion / plantar flexion suspension anchor point fixing belt through the nylon buckle 430, the contact force between the calf binding module and the skin can be further adjusted to limit the sliding of the binding module during the application of auxiliary force. At the same time, the position of the suspension anchor point can be quickly adjusted, which not only does not limit the freedom of movement of the wearer's ankle joint, but also can avoid excessive relaxation of the Bowden cable core to the greatest extent.

[0060] like Figure 6 and Figure 7As shown, the ankle-foot fixation module 3 includes a toe fixation device 31 and a heel fixation device 32, and the toe fixation device 31 and the heel fixation device 32 are connected by an arch band 33. The main body of the arch band 33 is a high-elastic elastic band, and Velcro is used at the bottom to further adjust the initial length of the elastic band. The elastic design enables the exoskeleton to adapt to different foot types and provide personalized support and stability. The toe fixation device 31 includes a dorsiflexion side fixed anchor point 311, a toe limit structure 312, a forefoot support structure 313 and a front foot fixed wing 314. The toe limit structure 312 can prevent the wearer's foot from sliding out of the fixation module, and the forefoot support structure 313 is used to provide support for the forefoot. The bottoms of the toe limit structure 312 and the front foot fixed wing 314 are fixed on the forefoot support structure 313. A first pull ring 315 is provided on the dorsiflexion side fixed anchor point 311, which is connected to the first tension sensor through the first pull ring 315. The end of the dorsiflexion side Bowden wire core 401 passes through the first pull ring 315 and is fixed by a second clamp 316. The second clamp 316 is a stainless steel wire rope clamp.

[0061] A BOA lacing system 321 is provided at the rear side of the heel fixing device 32. A first hanging ring device 322 and a second hanging ring device 323 are provided on both sides of the BOA lacing system 321, a first fixed pulley 324 and a second fixed pulley 325 are provided on both sides of the lower end of the first hanging ring device 322, and a third fixed pulley 326 and a fourth fixed pulley 327 are provided on both sides of the lower end of the second hanging ring device 323. Four sets of fixed pulley brackets and fixed pulleys are fixed to both sides of the heel fixing device 32 by locking screws. The second hanging ring device 323 includes a tension spring fixing seat 3231, a tension spring 3232 and a hanging ring 3233, and the upper end of the tension spring 3232 is connected to the tension spring fixing seat 3231, and the lower end is connected to the hanging ring 3233. The ropes on both sides of the BOA lacing system 321 pass through the first fixed pulley 324, the first hanging ring device 322, the second fixed pulley 325, the wire hole on the toe fixing device 31, the third fixed pulley 326, the second hanging ring device 323 and the fourth fixed pulley 327 respectively. The tightness of the rope is changed by rotating the BOA knob of the BOA lacing system 321 to adjust the fixation degree of the wearer's foot.

[0062] The heel fixing device 32 is also provided with a plantar flexion side fixed anchor point 328, a toothed belt fixing structure 329, a fine-adjustment buckle fixing structure 3210 and an inertial sensor fixing structure 3211. The plantar flexion side fixed anchor point 328 is provided with a second pull ring 3212, which is connected to the second tension sensor through the second pull ring 3212. The end of the plantar flexion side Bowden wire core 402 passes through the second pull ring 3212 and is fixed by a third clamp 3213. The third clamp 3213 is a stainless steel wire rope clamp. The heel fixing device 32 is used to firmly fix the heel position. The Kraft energy belt and the fine-adjustment buckle are installed on the toothed belt fixing structure 329 and the fine-adjustment buckle fixing structure 3210 by screws and nuts, and the Kraft energy belt is passed through the fine-adjustment buckle, which can ensure that the exoskeleton will not slide or shift during the movement of the lower limbs, and further prevent the heel from detaching from the exoskeleton device. The inertial sensor fixing structure 3211 is used to fix the inertial sensor to prevent the sensor from being displaced relative to the wearer's ankle.

[0063] like Figure 8 As shown, the first hanging ring device 322 includes a winding wheel 3221. A pull rope 3222 is fixedly wound around the winding portion of the winding wheel 3221, a torsion spring 3223 is welded on one side of the winding wheel 3221, and the end of the pull rope 3222 passes through a hanging ring 3224. After passing through the hanging ring 3224, the pull rope 3222 is fixed using a first clamp 3225.

[0064] The first hanging ring device 322 also includes an encoder support base 3226 and a winding wheel support base 3227. An encoder that can be used for a mouse wheel is installed on the inner side of the encoder support base 3226. The side of the winding wheel 3221 close to the encoder support base 3226 is slidably connected to the encoder's card slot, and the side of the torsion spring 3223 away from the winding wheel 3221 is fixed in the winding wheel support base 3227. After the end of the pull rope 3222 passes through the lower end notch of the winding wheel support base 3226 and the hanging ring 3224, it is fixed with the first clamp 3225. The encoder support base 3226 is fixedly connected to the winding wheel support base 3227 by a cross round head screw and a hexagon socket nut. During actual use, the rope of the BOA strap system 321 will apply a downward pulling force to the hanging ring 3224 of the first hanging ring device 322 and the hanging ring 3233 of the second hanging ring device 323 during the tightening process, causing the ends of the hanging ring 3224 and the ends of the hanging ring 3233 to move downward, thereby stretching the torsion spring 3223 and the tension spring 3232. When the downward pulling force is removed, the spring system will automatically restore the system to its initial position.

[0065] In the actual wearing process of the rope-driven exoskeleton, the ankle-foot fixation module 3 can be worn for the first time, and the Kraft energy belt can be inserted into the fine-tuning buckle to adjust the tightness of the heel fixation device 32. The front-to-back distance between the toe fixation device 31 and the heel fixation device 32 can be adjusted through the Velcro at the bottom of the arch band 33 to adapt it to the wearer's foot size. Then the BOA knob of the BOA lacing system 321 on the back of the heel is rotated to tighten the inelastic rope of the BOA lacing system 321. At this time, the arch band 33 and the inelastic rope act on both sides of the upper / lower foot at the same time, firmly connecting the toe fixation device 31 and the heel fixation device 32 to the wearer's foot. Then put on the calf binding module 2, first put on the calf binding lining 21, place the zipper structure 24 on the inner side of the calf, and adjust the flexible strap structure 23 to initially fix the calf binding module 2 to the middle of the wearer's calf, and then fix the dorsiflexion suspension anchor point 4311 and the plantar flexion suspension anchor point 4321 to the calf binding module 2 through the dorsiflexion suspension anchor point fixing belt 431 and the plantar flexion suspension anchor point fixing belt 432, adjust the nylon buckle 440 to further increase the fit of the binding module, and finally firmly bind the bidirectional drive module 1 near the center of mass of the human body through the waist binding module. Based on the first hanging ring device 322 and the inertial sensor IMU, the gait division is completed, and the bidirectional drive module 1 is used to drive the dorsiflexion side Bowden wire core 401 and the plantar flexion side Bowden wire core 402 to provide dorsiflexion assistance and plantar flexion assistance for the wearer. There is no need to adjust the arch strap 33, the flexible strap structure 23 and the Velcro 440 during the subsequent wearing process, making the exoskeleton easy, simple and quick to wear.

[0066] The present invention discloses a rope-driven ankle-foot exoskeleton robot, which mainly includes a bidirectional driving module 1, a calf binding module 2 and an ankle-foot fixation module 3. The bidirectional driving module 1 is mainly composed of a joint motor 11 and an assembled winding wheel 13. The assembled winding wheel 13 simulates the contraction of the human calf muscles by bidirectionally driving the Bowden cable through a single motor, thereby assisting the plantar flexion and dorsiflexion of the ankle joint of patients with mild hemiplegia. The designed calf binding module 2 has the characteristics of quickly adjusting the tightness and the position of the suspension anchor point, ensuring that it is easy and comfortable to wear. The ankle-foot fixation module 3 adopts a front-to-back separation design, which can adapt to differentiated individuals, and can divide the gait support phase into three stages based on the first hanging ring device 322 and the second hanging ring device 323: the initial support, the middle support and the final support.

[0067] The embodiment of the present invention further provides a control method for a rope-driven ankle-foot exoskeleton robot, which is applicable to the above-mentioned rope-driven ankle-foot exoskeleton robot and includes the following steps:

[0068] Step S1: collecting gait data of the wearer during walking through a first hanging ring device fixed on the heel fixing device and an inertial sensor.

[0069] Step S2: Identify the wearer's current gait phase according to the gait data, and calculate the control parameters of the bidirectional drive module according to the current gait phase and the expected ankle joint motion trajectory.

[0070] Step S3: According to the control parameters, the bidirectional driving module is controlled to transmit power to the calf binding module and the ankle-foot fixing module to drive the wearer to walk.

[0071] Step S4: dynamically adjusting the control parameters according to the actual motion trajectory of the wearer fed back by the first hanging ring device and the inertial sensor.

[0072] Step S5: Repeat steps S1 to S4 until the wearer completes rehabilitation training.

[0073] The fixed pulley bracket, the fixed pulley, the wire hole near the heel of the front fixed wing, the first lifting ring device and the tension spring are simplified as follows Fig. 9 The gait detection device schematic diagram is shown in FIG. The gait phase of a human body during walking can be roughly divided into the support phase and the swing phase, wherein the support phase can be further divided into: the initial support phase, the middle support phase and the final support phase. Fig. 9 The figure shows a schematic diagram of the gait detection device for starting and mid-stance. In the starting stage, the wearer tightens the inelastic rope by rotating the BOA knob, and preliminarily determines that the encoder threshold is 180°. When the encoder value is greater than the set threshold, it indicates that it has entered the mid-stance. In this phase, the distance between the wire hole B near the heel of the front fixed wing of the foot and the rotation center O of the toe joint is d, the distance between B and the fixed pulley point A is l1, the distance between AO is m1, and the angle between AO and BO is θ1. Fig.10 The figure shows a schematic diagram of the gait detection device at the end of the support phase. As the toe joint rotates, the distance d between BO remains unchanged, and the distance between AO is m2. Since the position of the rotation center O remains unchanged, m1 = m2, and the angle between AO and BO becomes θ2. At this time, θ2 < θ1, and the distance between AB becomes l2. According to the cosine theorem: At the same time, since the whole sole of the foot is not touched on the ground in other gait phases except the mid-stance phase, the schematic diagrams of the gait detection devices in other gait phases are the same as Fig.10 When the distance between AB is shortened, the force applied to the hanging ring and the lifting ring is reduced, so that the torsion spring and the tension spring rebound and the encoder value is lower than the threshold.

[0074] like Fig.11As shown, the wearer's ankle joint angle and angular velocity are measured by the inertial sensor IMU, the peak detection algorithm is used to detect the transition of the gait phase from the end of the support phase to the beginning of the swing phase, and the zero-crossing detection algorithm is used to detect the transition of the gait phase from the end of the swing phase to the beginning of the support phase. After detecting that the gait phase enters the early stage of support, if the encoder value is higher than the set threshold, it indicates that it has entered the middle stage of support. If the encoder value is lower than the set threshold, it indicates that it has entered the late stage of support. During the movement, the forefoot support structure may slide slightly, causing the encoder value to change. The fixed threshold is sensitive to the walking rhythm. Therefore, an adaptive threshold iteration method is used in the embodiment of the present invention to compensate for the disturbance. The expression of the adaptive threshold iteration function is:

[0075]

[0076] In the formula, φ th is the encoder threshold, the initial value is set to 180°; is the average value of the maximum encoder value in the three historical gait cycles; It is the average of the minimum encoder values ​​in the three historical gait cycles.

[0077] On the basis of achieving accurate gait division, when the wearer's gait is detected to enter the swing phase, the following Fig.12 The force / position hybrid control algorithm shown in the figure realizes dorsiflexion assistance. The primary goal of walking assistance during the swing phase is to make the ankle dorsiflexion angle reach the target value, and then make the dorsiflexion assistance force reach the expected value before entering the initial support period, and finally use position control immediately after entering the initial support period to restore the motor to the initial rotation angle. Therefore, the expression of the force / position hybrid control algorithm is:

[0078]

[0079] In the above formula, k represents the kth gait cycle, θ(k) is the angular control value of the motor in the kth gait cycle; k α is the position proportionality coefficient, which is determined by the ratio of the ankle joint moment arm and the radius of the reel; is the desired dorsiflexion angle The maximum dorsiflexion angle measured in the previous gait cycle The difference, among which Preferably 10°; ω(k) is the motor rotation angle of the kth gait cycle; k β is the force / velocity proportionality coefficient, determined by experimental methods; ΔF is the desired dorsiflexion assist force F df The maximum dorsiflexion assisting force F at the end of the previous gait cycle d_last The difference between df Preferably 17N.

[0080] When When iterative position control is used, during the swing period, Use force-based iterative velocity control.

[0081] When the wearer enters the initial stage of support and the joint motor has returned to the initial rotation angle, if the expected force of the rope is detected to be greater than 0, the preload force is loaded. This process uses force-based iterative position control:

[0082]

[0083] Where x(k) is the position command at the end of the Bowden cable; Δx is a small position compensation, preferably 4 mm; For the expected preload force, take 15N; Maximum preload force measured by the tension sensor during the previous gait cycle.

[0084] When the system is preloaded, according to the expected force trajectory F d Achieve force control. Since the stiffness curve of the human-machine system will change due to individual differences, and the nonlinear problem introduced by the rope drive system makes the stiffness curve of the exoskeleton human-machine system hysteresis, the method of using a function to fit the system stiffness curve and identify the system control parameters online can achieve more accurate and personalized control.

[0085] like Fig.13 As shown in Figure 1, a force control algorithm based on stiffness adaptation is used in the plantar flexion assistance process. The stiffness curve of the human-machine system is fitted to obtain the magnitude of the applied force F and the displacement x of the end of the rope. e The functional relationship between them is:

[0086]

[0087] Where s is the stiffness coefficient of the system; is the maximum rope-type variable corresponding to the historical peak tension; C is the auxiliary force constant, corresponding to the expected peak force, from Fig.14 The force-displacement-system stiffness curve shown is obtained in a three-dimensional view.

[0088] In a gait cycle, the stiffness coefficient of the human-machine system is not a constant value, so the parameter s is used to characterize the system stiffness. The system stiffness is identified by the historical cable end displacement. hour:

[0089]

[0090] In the formula, s d (k) is the system stiffness parameter obtained by identification; F l p (k-1) and The rope is loaded / unloaded to the k-1th gait cycle respectively. The size of the auxiliary force when .

[0091] In a gait cycle, the stiffness coefficient changes with the change of the gait phase. Therefore, the embodiment of the present invention corrects the identified system stiffness by adding a stiffness compensation amount s(i), where i is the discrete phase between a single gait cycle. The expression of the stiffness compensation amount s(i) is:

[0092] s(i)=s d (k)+Δs(i-1);

[0093] Δs(i-1)=s d (i-1)-s m (i-1);

[0094]

[0095] In the above formula, Δs(i) is the total stiffness coefficient compensation; F d (i) and F m (i) The expected force trajectory at the end of the Bowden cable and the force trajectory actually measured by the tension sensor, respectively.

[0096] Therefore, the displacement of the rope end after the preload is reached is:

[0097]

[0098] The total displacement at the end of the rope is then:

[0099] x all (i) = x(k) + x e (i).

[0100] Fig.15 This is a curve diagram of trajectory tracking using traditional PD control based on a constant system stiffness coefficient. It can be seen from the figure that the plantar flexion assist force has a significant error during the force unloading process. Fig.16 It is a force control method based on stiffness adaptation. As can be seen from the figure, it has a good trajectory tracking effect. In addition, the dorsiflexion assist force is close to the expected dorsiflexion assist force F at the end of the swing. df .

[0101] The ankle-foot fixation module of the embodiment of the present invention adopts a front-to-back separation design, which can adapt to lower limbs of different sizes, and can divide the gait support phase into three stages through a single encoder based on the structural characteristics of the flexible exoskeleton itself. In view of the nonlinear characteristics of the rope drive system, a force control algorithm based on stiffness adaptation is proposed. By identifying the system stiffness parameters, the force trajectory during the auxiliary force loading and unloading process is corrected, thereby improving the trajectory tracking performance of the flexible drive.

[0102] In summary, the present invention designs a rope-driven ankle-foot exoskeleton robot, and the rope drive has the characteristics of light weight, easy deployment, good flexibility, etc. The flexible ankle-foot exoskeleton uses flexible fabric to make the main structure, which can better fit the human body, has good portability and is easy to put on and take off. The components of the robot adopt a modular design, and the exoskeleton is divided into a two-way drive module, a calf binding module and an ankle-foot fixation module. The relative position between each module is easy to adjust, and the modules can adapt to individual differences during wearing. In order to reduce the shear force between the binding material and the human skin, the waist binding is fixed above the iliac crest, and the leg / waist binding lining is made of cotton material. The suspension anchor strap firmly fixes the plantar flexion side suspension anchor and the dorsiflexion side suspension anchor on the calf binding structure. The upper control unit drives the assembled winding wheel to drive the Bowden line core in a two-way manner to achieve plantar flexion / dorsiflexion assistance by simulating the contraction of the calf muscles, which solves the problems of plantar flexor weakness and foot drop for hemiplegic wearers. The position of the rope transmission device on the calf binding structure is easy to adjust, which can ensure rapid conversion between plantar flexion assistance and dorsiflexion assistance without interfering with the wearer's freedom of movement of the lower limbs.

[0103] The present invention designs a rope-driven ankle-foot exoskeleton robot control method, which uses a BOA knob to lead out a non-elastic rope in parallel with a torsion spring, a winding wheel and an encoder as a trigger medium for gait detection. In combination with an inertial sensor, the gait phase can be subdivided into the initial support phase, the middle support phase, the final support phase and the swing phase. By identifying the stiffness parameters of the system, the disturbance and error of the system can be compensated during the force control process, thereby achieving an accurate trajectory tracking effect, and providing a personalized control solution, which can effectively improve the tracking performance and adaptability of the exoskeleton system to meet the needs of different users. This solves the individual differences of the wearer and the nonlinear problems caused by the rope-driven system, such as dynamic changes and hysteresis in human-computer interaction.

[0104] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. Only the preferred embodiments of the present invention are expressed. The description is more specific and detailed, but it cannot be understood as limiting the scope of the present invention. As long as there is no contradiction in the combination of these technical features, they should be considered as within the scope of this specification.

[0105] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A rope-driven ankle-foot exoskeleton robot, characterized in that: include: A bidirectional driving module (1), the bidirectional driving module (1) being arranged above the iliac crest of a human body and being connected in sequence to a calf binding module (2) arranged at the calf and an ankle-foot fixing module (3) worn on the foot through a rope transmission device (4); The bidirectional driving module (1) transmits power to the calf binding module (2) and the ankle-foot fixing module (3) in sequence through the rope transmission device (4), thereby driving the ankle joint to perform dorsiflexion or plantar flexion movement.

2. A rope-driven ankle-foot exoskeleton robot according to claim 1, characterized in that: The bidirectional drive module (1) comprises a joint motor (11), a first deep groove ball bearing (12), an assembled winding wheel (13) and a second deep groove ball bearing (14) are sequentially arranged along the axial direction of the joint motor (11), the assembled winding wheel (13) comprising an inner wheel (131), a middle wheel (132) and an outer wheel (133), the inner wheel (131) being fixed to the inner ring of the first deep groove ball bearing (12), and the central axis of the outer wheel (133) being fixed to the inner ring of the second deep groove ball bearing (14).

3. The rope-driven ankle-foot exoskeleton robot according to claim 2, characterized in that: The rope transmission device (4) comprises a dorsiflexion side Bowden wire core (401) and a plantar flexion side Bowden wire core (402), the upper ends of the dorsiflexion side Bowden wire core (401) and the plantar flexion side Bowden wire core (402) are respectively fixedly wound on the inner and outer wheels of the assembled winding wheel (13), and the lower ends are respectively fixedly connected to the toe fixing device (31) and the heel fixing device (32) of the ankle-foot fixing module (3).

4. The rope-driven ankle-foot exoskeleton robot according to claim 3, characterized in that: A BOA lacing system (321) is arranged at the rear side of the heel fixing device (32), a first hanging ring device (322) and a second hanging ring device (323) are arranged at both sides of the BOA lacing system (321), a first fixed pulley (324) and a second fixed pulley (325) are arranged at both sides of the lower end of the first hanging ring device (322), and a third fixed pulley (326) and a fourth fixed pulley (327) are arranged at both sides of the lower end of the second hanging ring device (323); The ropes on both sides of the BOA lacing system (321) pass through the first fixed pulley (324), the first hanging ring device (322), the second fixed pulley (325), the third fixed pulley (326), the second hanging ring device (323), the fourth fixed pulley (327) and the wire holes on the toe fixing device (31) respectively, and the tightness of the ropes is changed by rotating the BOA knob of the BOA lacing system (321) to adjust the fixation degree of the wearer's foot.

5. The rope-driven ankle-foot exoskeleton robot according to claim 4, characterized in that: The first hanging ring device (322) comprises a winding wheel (3221), a pulling rope (3222) is fixedly wound around the winding portion of the winding wheel (3221), a torsion spring (3223) is welded on one side of the winding wheel (3221), and the end of the pulling rope (3222) passes through the hanging ring (3224) and is fixed using a first clamp (3225).

6. A control method for a rope-driven ankle-foot exoskeleton robot, applicable to a rope-driven ankle-foot exoskeleton robot as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Step S1: collecting gait data of the wearer during walking; Step S2: identifying the current gait phase of the wearer according to the gait data, and calculating the control parameters of the bidirectional driving module according to the current gait phase and the expected ankle joint motion trajectory; Step S3: controlling the bidirectional driving module to transmit power to the calf binding module and the ankle-foot fixing module according to the control parameters, so as to drive the wearer to walk; Step S4: dynamically adjusting the control parameters according to the actual motion trajectory of the wearer fed back by the first hanging ring device and the inertial sensor; Step S5: Repeat steps S1 to S4 until the wearer completes rehabilitation training.

7. The control method of a rope-driven ankle-foot exoskeleton robot according to claim 6, characterized in that: When identifying the current gait phase of the wearer according to the gait data in step S2, an adaptive threshold iteration method is used to compensate for disturbances in the gait data collection process. The expression of the adaptive threshold iteration method is: In the formula, φ th is the encoder threshold, the initial value is set to 180°; is the average value of the maximum encoder value in the three historical gait cycles; It is the average of the minimum encoder values ​​in the three historical gait cycles.

8. The control method of a rope-driven ankle-foot exoskeleton robot according to claim 6, characterized in that: The control parameters of the bidirectional drive module are calculated according to the current gait stage and the expected ankle joint motion trajectory as described in step S2, including the following steps: when it is detected that the wearer's gait enters the swing phase, a force / position hybrid control algorithm is used to implement dorsiflexion assistance; when it is detected that the wearer's gait enters the initial support phase and the joint motor has returned to the initial rotation angle, it is determined whether the expected force at the end of the Bowden cable is greater than 0 at this time. If so, the preload is started, and the first displacement of the rope is implemented by force-based iterative position control. After the preload is reached, a stiffness adaptive force control algorithm is used to implement the second displacement of the rope to implement plantar flexion assistance.

9. The control method of a rope-driven ankle-foot exoskeleton robot according to claim 8, characterized in that: The expression of the force / position hybrid control algorithm is: In the above formula, k represents the kth gait cycle, θ(k) is the angular control value of the motor in the kth gait cycle; k α is the position scale factor; is the desired dorsiflexion angle The maximum dorsiflexion angle measured in the previous gait cycle The difference between the two; ω(k) is the motor rotation angle of the kth gait cycle; k β is the force / speed proportionality coefficient; ΔF is the desired dorsiflexion assist force F df The maximum dorsiflexion assisting force F at the end of the previous gait cycle d_last difference.

10. The control method of a rope-driven ankle-foot exoskeleton robot according to claim 8, characterized in that: The expression of the stiffness adaptive force control algorithm is: s(i)=s d (k)+Δs(i-1); Δs(i-1)=s d (i-1)-s m (i-1); In the above formula, i is the discrete phase between a single gait cycle, x e (i) is the displacement of the rope end after the preload is reached; is the maximum rope-type variable corresponding to the historical peak tension; s(i) is the stiffness compensation; F d (i) is the expected force trajectory at the end of the rope; F m (i) is the tension at the end of the rope measured by the tension sensor; C is the auxiliary force constant; s d (k) is the stiffness parameter; Δs(i) is the total stiffness coefficient compensation; F l p (k-1) and The rope is loaded / unloaded to the k-1th gait cycle respectively. The size of the auxiliary force at s d (i) and s m (i) are the expected stiffness parameters of the human-machine system and the identified stiffness parameters of the human-machine system at phase i; 1 / n is the ratio of the rope end type variable to the maximum rope type variable corresponding to the historical peak tension at phase i-1.

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